Patent Publication Number: US-8113126-B2

Title: Rail road car truck and bolster therefor

Description:
This application is a continuation of U.S. application Ser. No. 11/002,222 filed Dec. 3, 2004, now U.S. Pat. No. 7,631,603, which is hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to the field of rail road cars, and, more particularly, to the field of three piece rail road car trucks for rail road cars. 
     BACKGROUND OF THE INVENTION 
     Rail road cars in North America commonly employ double axle swiveling trucks known as “three piece trucks” to permit them to roll along a set of rails. The three piece terminology refers to a truck bolster and pair of first and second sideframes. In a three piece truck, the truck bolster extends cross-wise relative to the sideframes, with the ends of the truck bolster protruding through the sideframe windows. Forces are transmitted between the truck bolster and the sideframes by spring groups mounted in spring seats in the sideframes. The sideframes carry forces to the sideframe pedestals. The pedestals seat on bearing adapters, whence forces are carried in turn into the bearings, the axle, the wheels, and finally into the tracks. The 1980 Car &amp; Locomotive Cyclopedia states at page 669 that the three piece truck offers “interchangeability, structural reliability and low first cost but does so at the price of mediocre ride quality and high cost in terms of car and track maintenance.” 
     Ride quality can be judged on a number of different criteria. There is longitudinal ride quality, where, often, the limiting condition is the maximum expected longitudinal acceleration experienced during humping or flat switching, or slack run-in and run-out. There is vertical ride quality, for which vertical force transmission through the suspension is the key determinant. There is lateral ride quality, which relates to the lateral response of the suspension. There are also other phenomena to be considered, such as truck hunting, the ability of the truck to self steer, and, whatever the input perturbation may be, the ability of the truck to damp out undesirable motion. These phenomena tend to be inter-related, and the optimization of a suspension to deal with one phenomenon may yield a system that may not necessarily provide optimal performance in dealing with other phenomena. 
     In terms of optimizing truck performance, it may be advantageous to be able to obtain a relatively soft dynamic response to lateral and vertical perturbations, to obtain a measure of self steering, and yet to maintain resistance to lozenging (or parallelogramming). Lozenging, or parallelogramming, is non-square deformation of the truck bolster relative to the side frames of the truck as seen from above. Self steering may tend to be desirable since it may reduce drag and may tend to reduce wear to both the wheels and the track, and may give a smoother overall ride. 
     Among the types of truck discussed in this application are swing motion trucks. An earlier patent for a swing motion truck is U.S. Pat. No. 3,670,660 of Weber et al., issued Jun. 20, 1972. This truck has unsprung lateral cross bracing, in the nature of a transom that links the sideframes together. By contrast, the description that follows describes several embodiments of truck that do not employ lateral unsprung cross-members, but that may use damper elements mounted in a four-cornered arrangement at each end of the truck bolster. An earlier patent for dampers is U.S. Pat. No. 3,714,905 of Barber, issued Feb. 6, 1973. 
     SUMMARY OF THE INVENTION 
     The present invention may provide a rail road car truck with bi-directional rocking at the sideframe pedestal to wheelset axle end interface. It may also provide a truck that has self steering that is proportional to the weight carried by the truck. It may further have a longitudinal rocker at the sideframe to axle end interface. Further it may provide a swing motion truck with self steering. It may also provide a swing motion truck that has the combination of a swing motion lateral rocker and an elastomeric bearing adapter pad. 
     In an aspect of the invention, there is a wheelset-to-sideframe interface assembly for a railroad car truck. The interface assembly has a bearing adapter and a mating pedestal seat. The bearing adapter has first and second ends that form an interlocking insertion between a pair of pedestal jaws of a railroad car sideframe. The bearing adapter has a first rocking member. The pedestal seat has a second rocking member. The first and second rocking members are matingly engageable to permit lateral and longitudinal rocking between them. There is a resilient member mounted between the bearing adapter and pedestal seat. The resilient member has a portion formed that engages the first end of the bearing adapter. The resilient member has an accommodation formed to permit the mating engagement of the first and second rocking members. 
     In a feature of that aspect of the invention, the resilient member has the first and second ends formed for interposition between the bearing adapter and the pedestal jaws of the sideframe. In another feature, the resilient member has the form of a Pennsy Pad with a relief formed to define the accommodation. In a further feature, the resilient member is an elastomeric member. In yet another feature, the elastomeric member is made of rubber material. In still another feature, the elastomeric member is made of a polyurethane material. In yet a further feature, the accommodation is formed through the elastomeric material and the first rocking member protrudes at least part way through the accommodation to meet the second rocking member. In an additional feature, the bearing adapter is a bearing adapter assembly which includes a bearing adapter body surmounted by the first rocker member. In another additional feature, the first rocker member is formed of a different material from the bearing body. In a further additional feature, the first rocker member is an insert. 
     In yet another additional feature, the first rocker member has a footprint with a profile conforming to the accommodation. In still another additional feature, the profile and the accommodation are mutually indexed to discourage mis-orientation of the first rocker member relative to the bearing adapter. In yet a further additional feature, the body and the first rocker member are keyed to discourage mis-orientation between them. In a further feature, the accommodation is formed through the resilient member and the second rocking member protrudes at least part way through said accommodation to meet the first rocking member. In another further feature, the pedestal seat includes an insert with the second rocking member formed in it. In yet another further feature, the second rocker member has a footprint with a profile conforming to the accommodation. 
     In still a further feature, the portion of the resilient member that is formed to engage the first end of the bearing adapter, when installed, includes elements that are interposed between the first end of the bearing adapter and the pedestal jaw to inhibit lateral and longitudinal movement of the bearing adapter relative to the jaw. 
     In another aspect of the invention the ends of the bearing adapter includes an end wall bracketed by a pair of corner abutments. The end wall and corner abutments define a channel to permit the sliding insertion of the bearing adapter between the pedestal jaw of the sideframe. The portion of the resilient member that is formed to engage the first end of the bearing adapter is the first end portion. The resilient member has a second end portion that is formed to engage the second end of the bearing adapter. The resilient member has a middle portion that extends between the first and second end portions. The accommodation is formed in the middle portion of the resilient member. In another feature, the resilient member has the form of a Pennsy Pad with a central opening formed to define the accommodation. 
     In another aspect of the invention, a wheelset-to-sideframe interface assembly for a rail road car truck has an interface assembly that has a bearing adapter, a pedestal seat and a resilient member. The bearing adapter has a first end and a second end that each have a end wall bracketed by a pair of corner abutments. The end wall and corner abutments co-operate to define a channel that permits insertion of the bearing adapter between a pair of thrust lugs of a sidewall pedestal. The bearing adapter has a first rocking member. The pedestal seat has a second rocking member to make engagement with the first rocking member. The first and second rocking members, when engaged, are operable to rock longitudinally relative to the sideframe to permit the rail road car truck to steer. The resilient member has a first end portion that is engageable with the first end of the bearing adapter for interposition between the first end of the bearing adapter and the first pedestal jaw thrust lug. The resilient member has a second end portion that is engageable with the second end of the bearing adapter for interposition between the second end of the bearing adapter and the second pedestal jaw thrust lug. The resilient member has a medial portion lying between the first and second end portions. The medial portion is formed to accommodate mating rocking engagement of the first and second rocking members. 
     In another feature, there is a resilient pad that is used with the bearing adapter which has a rocker member for mating and the rocking engagement with the rocker member of the pedestal seat. The resilient pad has a first portion for engaging the first end of the bearing adapter, a second portion for engaging a second end of the bearing adapter and a medial portion between the first and second end portions. The medial portion is formed to accommodate mating engagement of the rocker members. 
     In a feature of the aspect of the invention there is a wheelset-to-sideframe assembly kit that has a pedestal seat for mounting in the roof of a rail road car truck sideframe pedestal. There is a bearing adapter for mounting to a bearing of a wheelset of a rail road car truck and a resilient member for mounting to the bearing adapter. The bearing adapter has a first rocker element for engaging the seat in rocking relationship. The bearing adapter has a first end and a second end, both ends having an endwall and a pair of abutments bracketing the end wall to define a channel, that permits sliding insertion of the bearing adapter between a pair of sideframe pedestal jaw thrust lugs. The resilient member has a first portion that conforms to the first end of the bearing adapter for interpositioning between the bearing adapter and a thrust lug. The resilient member has a second portion connected to the first portion that, as installed, at least partially overlies the bearing adapter. 
     In another feature, the wheelset-to-sideframe assembly kit has a second portion of the resilient member with a margin that has a profile facing toward the first rocker element. The first rocker element is shaped to nest adjacent to the profile. In a further feature, wheelset-to-sideframe assembly kit has a bearing adapter that includes a body and the first rocker element is separable from that body. In still another feature, the wheelset-to-sideframe assembly kit has a second portion of the resilient member with a margin that has a profile facing toward the first rocker element which is shaped to nest adjacent the profile. In yet still another feature, the wheelset-to-sideframe assembly kit has a profile and first rocker element shaped to discourage mis-orientation of the first rocker element when installed. In another feature, the wheelset-to-sideframe assembly kit has a first rocker element with a body that is mutually keyed to facilitate the location of the first rocker element when installed. In still another feature, the wheelset-to-sideframe assembly kit has a first rocker element and body that are mutually keyed to discourage mis-orientation of the rocker element when installed. In yet still another feature, the wheelset-to-sideframe assembly kit has a first rocker element and a body with mutual engagement features. The features are mutually keyed to discourage mis-orientation of the rocker element when installed. 
     In a further feature, the kit has a second resilient member that conforms to the second end of the bearing adapter. In another feature, the wheelset-to-sideframe assembly kit includes a pedestal seat engagement fitting for locating the resilient feature relative to the pedestal seat on the assembly. In yet still another feature, the resilient member includes a second end portion that conforms to the second end of the bearing adapter. 
     In an additional feature, there is a bearing adapter for transmitting load between the wheelset bearing and a sideframe pedestal of a railroad car truck. It has at least a first and second land for engaging the bearing and a relief formed between the first and second land. The relief extends predominantly axially relative to the bearing. In another additional feature, the lands are arranged in an array that conforms to the bearing and the relief is formed at the apex of the array. In still another additional feature, the bearing adapter includes a second relief that extends circumferentially relative to the bearing. In yet still another additional feature, the axially extending relief and the circumferentially extending relief extends along a second axis of symmetry of the bearing adapter. 
     In a further feature, the radially extending relief extends along a first axis of symmetry of the bearing adapter and the circumferentially extending relief extends along a second axis of symmetry of the bearing adapter. In still a further feature, the bearing adapter has lands that are formed on a circumferential arc. In yet still another feature, the bearing adapter has a rocker element that has an upwardly facing rocker surface. In yet still a further feature, the bearing adapter has a body with a rocker element that is separable from the body. 
     In another aspect of the invention, there is a bearing adapter for installation in a rail road car truck sideframe pedestal. The bearing adapter has an upper portion engageable with a pedestal seat, and a lower portion engageable with a bearing casing. The lower portion has an apex. The lower portion includes a first land for engaging a first portion of the bearing casing, and a second land region for engaging a second portion of the bearing casing. The first land lies to one side of the apex. The second land lies to the other side of the apex. At least one relief located between the first and second lands. 
     In an additional feature, the relief has a major dimension oriented to extend along the apex in a direction that runs axially relative to the bearing when installed. In another feature, the relief is located at the apex. In another feature there are at least two the reliefs, the two reliefs lying to either side of a bridging member, the bridging member running between the first and second lands. 
     In another aspect of the invention there is a kit for retro-fitting a railroad car truck having elastomeric members mounted over bearing adapters. The kit includes a mating bearing adapter and a pedestal seat pair. The bearing adapter and the pedestal seat have co-operable bi-directional rocker elements. The seat has a depth of section of greater than ½ inches. 
     In another aspect of the invention, there is a railroad car truck having a bolster and a pair of co-operating sideframes mounted on wheelsets for rolling operation along railroad tracks. Truck has rockers mounted between the sideframes to permit lateral swinging of the sideframes. The truck is free of lateral unsprung cross-bracing between the sideframes. The sideframes each have a lateral pendulum height, L, measured between a lower location at which gravity loads are passed into the sideframe, and an upper location at the rocker where a vertical reaction is passed into the sideframes. The rocker includes a male element having a radius of curvature, r 1 , and a ratio of r 1 :L is less than 3. 
     In a further feature of that aspect, the rocker has a female element in mating engagement with the male element. The female element has a radius of curvature R 1  that is greater than r 1 , and the factor [(1/L.)/((1/r 1 )−(1/R 1 ))] is less than 3. In another further feature, R 1  is at least 4/3 as large as r 1 , and r 1  is greater than 15 inches. 
     In an aspect of the present invention, there is a rail road car truck that has a self steering capability and friction dampers in which the co-efficients of static and dynamic friction are substantially similar. It may include the added feature of lateral rocking at the sideframe pedestal to wheelset axle end interface. It may include self steering proportional to the weight carried by the truck. It may further have a longitudinal rocker at the sideframe to axle end interface. Further it may provide a swing motion truck with self steering. It may also provide a swing motion truck that has the combination of a swing motion lateral rocker and an elastomeric bearing adapter pad. In another feature, the truck may have dampers lying along the longitudinal centerline of the spring groups of the truck suspensions. In another feature, it may include dampers mounted in a four cornered arrangement. In another feature it may include dampers having modified friction surfaces on both the friction bearing face and on the obliquely angled face of the damper that seats in the bolster pocket. 
     In another aspect of the invention, a three piece rail road car truck has a truck bolster mounted transversely between a pair of sideframes. The truck bolster has ends, each of the ends being resiliently mounted to a respective one of the sideframes. The truck has a set of dampers mounted in a four cornered damper arrangement between each the bolster end and its respective sideframe. Each damper has a bearing surface mounted to work against a mating surface at a friction interface in a sliding relationship when the bolster moves relative to the sideframes. Each damper has a seat against which to mount a biasing device for urging the bearing face against the mating surface. The bearing surface of the damper has a dynamic co-efficient of friction and a static co-efficient of friction when working against the mating surface. The static and dynamic co-efficients of friction are of substantially similar magnitude. 
     In a further feature of that aspect of the invention, the co-efficients of friction have respective magnitudes within 10% of each other. In another feature, the co-efficients of friction are substantially equal. In another feature the co-efficients of friction lie in the range of 0.1 to 0.4. In still another feature, the co-efficients of friction lie in the range 0.2 to 0.35. In a further feature, the co-efficients of friction are about 0.30 (+/−10%). In still another feature, the dampers each include a friction element mounted thereto, and the bearing surface is a surface of the friction element. In yet still another feature, the friction element is a composite surface element that includes a polymeric material. 
     In another feature of that aspect of the invention, the truck is a self-steering truck. In another feature, the truck includes a bearing adapter to sideframe pedestal interface that includes a self-steering apparatus. In another feature, the self-steering apparatus includes a rocker. In a further feature, the truck includes a bearing adapter to sideframe pedestal interface that includes a self-steering apparatus having a force-deflection characteristic varying as a function of vertical load. In still another feature, the truck has a bearing adapter to sideframe pedestal interface that includes a bi-directional rocker operable to permit lateral rocking of the sideframes and to permit self-steering of the truck. 
     In another feature of that aspect of the invention, each damper has an oblique face for seating in a damper pocket of a truck bolster of a rail road car truck, the bearing face is a substantially vertical face for bearing against a mating sideframe column wear surface, and, in use, the seat is oriented to face substantially downwardly. In another feature, the oblique face has a surface treatment for encouraging sliding of the oblique face relative to the damper pocket. In still another feature, the oblique face has a static coefficient of friction and a dynamic co-efficient of friction, and the co-efficients of static and dynamic friction of the oblique face are substantially equal. In a further feature, the oblique face and the bearing face both have sliding surface elements, and both of the sliding surface elements are made from materials having a polymeric component. In yet a further feature, the oblique face has a primary angle relative to the bearing surface, and a cross-wise secondary angle. 
     In another aspect of the invention, there is a three piece railroad car truck having a bolster transversely mounted between a pair of sideframes, and wheelsets mounted to the sideframes at wheelset to sideframe interface assemblies. The wheelset to sideframe interface assemblies are operable to permit self steering, and include apparatus operable to urge the wheelsets in a lengthwise direction relative to the sideframes to a minimum potential energy position relative to the sideframes. The self-steering apparatus has a force deflection characteristic that is a function of vertical load. 
     In a further aspect of the invention, there is a bearing adapter for a railroad car truck. The bearing adapter has a body for seating upon a bearing of a rail road truck wheelset, and a rocker member for mounting to the body. The rocker member has a rocking surface, the rocking surface facing away from the body when the rocker member is mounted to the body, and the rocker being made of a different material from the body. 
     In a further feature of that aspect, the rocker member is made from a tool steel. In another feature of that aspect of the invention, the rocker member is made from a metal of a grade used for the fabrication of ball bearings. In another feature, the body is made of cast iron. In another feature, the rocker member is a bi-directional rocker member. In still another feature, the rocking surface of the rocking member defines a portion of a spherical surface. 
     In another aspect of the invention, there is a three piece railroad car truck having rockers for self steering. In still another aspect, there is a railroad car truck having a sideframe, an axle bearing, and a rocker mounted between the sideframe and the axle bearing. The rocker has a transverse axis to permit rocking of and the bearing lengthwise relative to the sideframe. 
     In another aspect of the invention there is a three piece railroad car truck having a bolster mounted transversely to a pair of sideframes. The side frames have pedestal fittings and wheelsets mounted in the pedestal fittings. The pedestal fittings include rockers. Each rocker has a transverse axis to permit rocking in a lengthwise direction relative to the sideframes. 
     In another aspect of the invention there is a three piece railroad car truck having a truck bolster mounted transversely to a pair of side frames, each sideframes has fore and aft pedestal seat interface fittings, and a pair of wheelsets mounted to the pedestal seat interface fittings. The pedestal seat interface fittings include rockers operable to permit the truck to self steer. 
     In another aspect of the invention there is a railroad car truck having a sideframe, an axle bearing, and a bi-directional rocker mounted between the sideframe and the axle bearing. In still another aspect of the invention, there is a railroad car truck having a truck bolster mounted transversely between a pair of sideframes, and wheelsets mounted to the sideframes to permit rolling operation of the truck along a set of rail road tracks. The truck includes rocker elements mounted between the sideframes and the wheelsets. The rocker elements are operable to permit lateral swinging of the sideframes and to permit self-steering of the truck. 
     In another aspect of the invention there is a railroad car truck having a pair of sideframes, a pair of wheelsets having ends for mounting to the sideframes, and sideframe to wheelset interface fittings. The sideframe to wheelset interface fittings include rocking members having a first degree of freedom permitting lateral swinging of the sideframes relative to the wheelsets, and a second degree of freedom permitting longitudinal rocking of the wheelset ends relative to the sideframes. 
     In another aspect of the invention there is a railroad car truck having rockers formed on a compound curvature, the rockers being operable to permit both a lateral swinging motion in the truck and self steering of the truck. In still another aspect of the invention, there is a railroad car truck having a pair of sideframes, a pair of wheelsets having ends for mounting to the sideframes, and sideframe to wheelset interface fittings. The sideframe to wheelset interface fittings include rocking members having a first degree of freedom permitting lateral swinging of the sideframes relative to the wheelsets, a second degree of freedom permitting longitudinal rocking of the wheelset ends relative to the sideframes. The wheelset to sideframe interface fittings being torsionally compliant about a predominantly vertical axis. 
     In aspect of the invention there is a swing motion rail road car truck modified to include rocking elements mounted to permit self-steering. In yet another aspect there is a swing motion rail road car truck having a transverse bolster sprung between a pair of side frames, and a pair of wheelsets mounted to the sideframes at wheelset to sideframe interface fittings. The wheelset to sideframe interface fittings include swing motion rockers and elastomeric members mounted in series with the swing motion rockers to permit the truck to self-steer. 
     In another aspect of the invention, there is a rail road car truck having a truck bolster mounted transversely between a pair of sideframes, and wheelsets mounted to the sideframes at wheelset to sideframe interface fittings. The wheelset to sideframe interface fittings include rockers for permitting lateral swinging motion of the sideframes. The rockers have a male element and a mating female element. The male and female rocker elements are engaged for co-operative rocking operation. The female element has a radius of curvature in the lateral swinging direction of less than 25 inches. The wheelset to sideframe interface fittings are also operable to permit self steering. 
     In still another aspect of the invention there is a rail road car truck having a truck bolster mounted transversely between a pair of sideframes, and wheelsets mounted to the sideframes at wheelset to sideframe interface fittings. The wheelset to sideframe interface fittings include rockers for permitting lateral swinging motion of the sideframes. The rockers have a male element and a mating female element. The male and female rocker elements are engaged for co-operative rocking operation. The sideframes have an equivalent pendulum length, L eq , when mounted on the rocker, of greater than 6 inches. The wheelset to sideframe interface fittings include an elastomeric member mounted in series with the rockers to permit self steering. 
     In yet another aspect of the invention there is a rail road car truck having a truck bolster mounted transversely between a pair of sideframes, and wheelsets mounted to the sideframes at wheelset to sideframe interface fittings. The wheelset to sideframe interface fittings include rockers for permitting self steering of the truck. The rockers have a male element and a mating female element. The male and female rocker elements are engaged for co-operative rocking operation, and the wheelset to sideframe interface fittings include an elastomeric member mounted in series with the rockers. 
     In still another aspect of the invention there is a rail road car truck having a transverse bolster sprung between two sideframes, and wheelsets mounted to the sideframes at wheelset to sideframe interface fittings, the truck having a spring groups and dampers seated in the bolster and biased by the spring groups to ride against the sideframes. The spring groups include a first damper biasing spring upon which a first damper of the dampers seats. The first damper biasing spring has a coil diameter. The first damper has a width of more than 150% of the coil diameter. 
     In another aspect of the invention there is a rail road car truck having a bolster having ends sprung from a pair of sideframes, and wheelsets mounted to the sideframes at wheelset to sideframe interface fittings. The wheelset to sideframe interface fittings include bi-directional rocker fittings for permitting lateral swinging of the sideframes and for permitting self steering of the wheelsets. The truck has a four cornered arrangement of dampers mounted at each end of the bolster. In a further feature of that aspect of the invention the interface fittings are torsionally compliant about a predominantly vertical axis. 
     In another aspect there is a railroad car truck having a bolster transversely mounted between a pair of sideframes, and wheelsets mounted to the sideframes. The rail road car truck has a bi-directional longitudinal and lateral rocking interface between each sideframe and wheelset, and four cornered damper groups mounted between each sideframe and the truck bolster. In an additional feature of that aspect of the invention the rocking interface is torsionally compliant about a predominantly vertical axis. In another additional feature, the rocking interface is mounted in series with a torsionally compliant member. 
     In yet another aspect of the invention there is a self-steering rail road car truck having a transversely mounted bolster sprung between two sideframes, and wheelsets mounted to the sideframes. The sideframes are mounted to swing laterally relative to the wheelsets. The truck has friction dampers mounted between the bolster and the sideframes. The friction dampers have co-efficients of static friction and dynamic friction. The co-efficients of static and dynamic friction being substantially the same. 
     In still another aspect there is a self-steering rail road car truck having a transversely mounted bolster sprung between two sideframes, and wheelsets mounted to the sideframes. The sideframes are mounted to swing laterally relative to the wheelsets. The truck has friction dampers mounted between the bolster and the sideframes. The friction dampers have co-efficients of static friction and dynamic friction. The co-efficients of static and dynamic friction differ by less than 10%. Expressed differently, the friction dampers having a co-efficient of static friction, us, and a co-efficient of dynamic friction, u k , and a ratio of u s /u k  lies in the range of 1.0 to 1.1. In another aspect of the invention, the truck has friction dampers mounted between the bolster and the sideframes in a sliding friction relationship that is substantially free of stick-slip behavior. In another feature of that aspect of the invention the friction dampers include friction damper wedges having a first face for engaging one of the sideframes, and a second, sloped, face for engaging a bolster pocket. The sloped face is mounted in the bolster pocket in a sliding friction relationship that is substantially free of stick-slip behavior. 
     In another aspect of the invention there is a self-steering rail road car truck having a bolster mounted between a pair of sideframes, and wheelsets mounted to the sideframes for rolling motion along railroad tracks. The wheelsets are mounted to the sideframes at wheelset to sideframe interface fittings. Those fittings are operable to permit lateral rocking of the sideframes. The truck has a set of friction dampers mounted between the bolster and each of the sideframes. The friction dampers have a first face in sliding friction relationship with the sideframes and a second face seated in a bolster pocket of the bolster. The first face, when operated in engagement with the sideframe, has a co-efficient of static friction and a co-efficient of dynamic friction, the co-efficients of static and dynamic friction of the first face differing by less than 10%. The second face, when mounted within the bolster pocket, has a co-efficient of static friction, and a co-efficient of dynamic friction, and the co-efficients of static and dynamic friction of the second face differing by less than 10%. 
     In yet another aspect of the invention there is a self-steering rail road car truck having a bolster mounted between a pair of sideframes, and wheelsets mounted to the sideframes for rolling motion along railroad tracks. The wheelsets are mounted to the sideframes at wheelset to sideframe interface fittings. The interface fittings are operable to permit lateral rocking of the sideframes. The truck has a set of friction dampers mounted between the bolster and each of the sideframes. The friction dampers have a first face in slidable friction relationship with the sideframes and a second face seated in a bolster pocket of the bolster. The first face and the side frame are co-operable and are in a substantially stick-slip free condition. The second face and the bolster pocket are also in a substantially stick-slip free condition. 
     In another aspect of the invention there is a rocker for a bearing adapter of a rail road car truck. The rocker has a rocking surface for rocking engagement with a mating surface of a pedestal seat of a sideframe of a railroad car truck. The rocking surface has a compound curvature to permit both lengthwise and sideways rocking. In a complementary aspect of the invention, there is a rocker for a pedestal seat of a sideframe of a rail road car truck. The rocker has a rocking surface for rocking engagement with a mating surface of a bearing adapter of a railroad car truck. The rocking surface has a compound curvature to permit both lengthwise and sideways rocking. 
     In an aspect of the invention there is a sideframe pedestal to axle bearing interface assembly for a three piece rail road car truck, the interface assembly having fittings operable to rock both laterally and longitudinally. 
     In an additional feature of that aspect of the invention the assembly includes mating surfaces of compound curvature, the compound curvature including curvature in both lateral and horizontal directions. In another feature, the assembly includes at least one rocker element and a mating element, the rocker and mating elements being in point contact with a mating element, the element in point contact being movable in rolling point contact with the mating element. In still another feature, the element in point contact is movable in rolling point contact with the mating element both laterally and longitudinally. In yet another feature, the fittings include rockingly matable saddle surfaces. 
     In another feature, the fittings include a male surface having a first compound curvature and a mating female surface having a second compound curvature in rocking engagement with each other, and one of the surfaces includes at least a spherical portion. In a further feature, the fittings include a non-rocking central portion in at least one direction. In still another feature, relative to a vertical axis of rotation, rocking motion of the fittings longitudinally is torsionally de-coupled from rocking of the fittings laterally. In a yet further feature the fittings include a force transfer interface that is torsionally compliant relative to torsional moments about a vertical axis. In still another feature, the assembly includes an elastomeric member. 
     In another aspect of the invention, there is a swing motion three piece rail road car truck having a laterally extending truck bolster, a pair of longitudinally extending sideframes to which the truck bolster is resiliently mounted, and wheelsets to which the side frames are mounted. Damper groups are mounted between the bolster and each of the sideframes. The damper groups each have a four-cornered damper layout, and wheelset to sideframe pedestal interface assemblies operable to permit lateral swinging motion of the sideframes and longitudinal self-steering of the wheelsets. 
     In a further aspect there is a rail road car truck having a truck bolster mounted between sideframes, and wheelsets to which the sideframes are mounted, and wheelset to sideframe interface assemblies by which to mount the sideframes to the wheelsets. The sideframe to wheelset interface assemblies include rocking apparatus to permit the sideframes to swing laterally. The rocking apparatus includes first and second surfaces in rocking engagement. At least a portion of the first surface has a first radius of curvature of less than 30 inches. The sideframe to wheelset interface includes self steering apparatus. 
     In a feature of that aspect of the invention, the self steering apparatus has a substantially linear force deflection characteristic. In another feature, the self steering apparatus has a force-deflection characteristic that varies with vertical loading of the sideframe to wheelset interface assembly. In a further feature, the force-deflection characteristic varies linearly with vertical loading of the sideframe to wheelset interface assembly. In another feature, the self steering apparatus includes a rocking element. In still another feature, the rocking element includes a rocking member subject to angular displacement about an axis transverse to one of the sideframes. 
     In another feature, the self steering apparatus includes male and female rocking elements, and at least a portion of the male rocking element has a radius of curvature of less than 45 inches. In still another feature, the self steering apparatus includes male and female rocking elements, and at least a portion of the female rocking element has a radius of curvature of less than 60 inches. In still another feature the self steering apparatus is self centering. In a further feature, the self steering apparatus is biased toward a central position. 
     In yet another feature, the self steering apparatus includes a resilient member. In a further feature of that further feature, the resilient member includes an elastomeric element. In another further feature, the resilient member is an elastomeric adapter pad assembly. In another feature, the resilient member is an elastomeric adapter assembly having a lateral force-displacement characteristic and a longitudinal force-displacement characteristic, and the longitudinal force-displacement characteristic is different from the lateral force-displacement characteristic. In another feature, the elastomeric adapter assembly is stiffer in lateral shear than in longitudinal shear. In again another feature, a rocker element is mounted above the elastomeric adapter pad assembly. In another feature, a rocker element is mounted directly upon the elastomeric adapter pad assembly. In a still further feature, the elastomeric adapter pad assembly includes and integral rocker member. In another feature, the three piece truck is a swing motion truck and the self steering apparatus includes an elastomeric bearing adapter pad. 
     In still another feature, the wheelsets have axles, and the axles have axes of rotation, and ends mounted beneath the sideframes, and, at one end of one of the axles, the self steering apparatus has a force deflection characteristic of at least one of the characteristics chosen from the set of force-deflection characteristic consisting of:
         (a) linear characteristic between 3000 lbs per inch and 10,000 pounds per inch of longitudinal deflection, measured at the axis of rotation at the end of the axle when the self steering apparatus bears one eighth of a vertical load of between 45,000 and 70,000 lbs.;   (b) linear characteristic between 16,000 lbs per inch and 60,000 pounds per inch of longitudinal deflection, measured at the axis of rotation at the end of the axle when the self steering apparatus bears one eighth of a vertical load of between 263,000 and 315,000 lbs.; and   (c) a linear characteristic between 0.3 and 2.0 lbs per inch of longitudinal deflection, measured at the axis of rotation at the end of the axle per pound of vertical load passed into the one end of the one axle.       

     In another aspect of the invention there is a three piece rail road freight car truck having self steering apparatus, wherein the passive steering apparatus includes at least one longitudinal rocker. 
     In an aspect of the invention, there is a three piece rail road freight car truck having passive self steering apparatus, the self steering apparatus having a linear force-deflection characteristic, and the force-deflection characteristic varying as a function of vertical loading of the truck. 
     In an additional feature of that aspect of the invention, the force-displacement characteristic varies linearly with vertical loading of the truck. In another feature, the self steering apparatus includes a rocker mechanism. In another feature, the rocker mechanism is displaceable from a minimum energy state under drag force applied to a wheel of one of the wheelsets. In still another feature, the force-deflection characteristic lies in the range of between about 0.4 lbs and 2.0 lbs per inch of deflection, measured at a center of and end of an axle of a wheelset of the truck per pound of vertical load passed into the end of the axle of the wheelset. In a further feature, the force deflection characteristic lies in the range of 0.5 to 1.8 lbs per inch per pound of vertical load passed into the end of the axle of the wheelset. 
     In yet another aspect of the invention there is a three piece rail road freight car truck having a transversely extending truck bolster, a pair of side frames mounted at opposite ends of the truck bolster, and resiliently connected thereto, and wheelsets. The sideframes are mounted to the wheelsets at sideframe to wheelset interface assemblies. At least one of the sideframe to wheelset interface assemblies is mounted between a first end of an axle of one of the wheelsets, and a first pedestal of a first of the sideframes. The wheelset to sideframe interface assembly includes a first line contact rocker apparatus operable to permit lateral swinging of the first sideframe and a second line contact rocker apparatus operable to permit longitudinal displacement of the first end of the axle relative to the first sideframe. 
     In a feature of that aspect of the invention, the first and second rocker apparatus are mounted in series with a torsionally compliant member, the torsionally complaint member being compliant to torsional moments applied about a vertical axis. In another feature, a torsionally compliant member is mounted between the first and second rocker apparatus, the torsionally compliant member being torsionally compliant about a vertical axis. 
     In a further aspect of the invention, there is a bearing adapter for a three piece rail road freight car truck, the bearing adapter having a rocking contact surface for rocking engagement with a mating surface of a sideframe pedestal fitting, the rocking contact surface of the bearing adapter having a compound curvature. 
     In another feature of that aspect of the invention, the compound curvature is formed on a first male radius of curvature and a second male radius of curvature oriented cross-wise thereto. In another feature, the compound curvature is saddle shaped. In a further feature, the compound curvature is ellipsoidal. In a further feature, the curvature is spherical. 
     In a still further aspect there is a railroad car truck having a laterally extending truck bolster. The truck bolster has first and second ends. First and second longitudinally extending sideframes are resiliently mounted at the first and second ends of the bolster respectively. The side frames are mounted on wheelsets at sideframe to wheelset mounting interface assemblies. A four cornered damper group is mounted between each end of the truck bolster and the respective side frame to which that end is mounted. The sideframe to wheelset mounting interface assemblies are torsionally compliant about a vertical axis. 
     In a feature of that aspect of the invention, the truck is free of unsprung lateral cross-members between the sideframes. In another feature, the sideframes are mounted to swing laterally. In still another feature, the sideframe to wheelset mounting interface assemblies include self steering apparatus. 
     In another aspect of the invention, there is a railroad freight car truck having wheelsets mounted in a pair of sideframes, the sideframes having sideframe pedestals for receiving the wheelsets. The sideframe pedestals have sideframe pedestal jaws. The sideframe pedestal jaws include sideframe pedestal jaw thrust blocks. The wheelsets have bearing adapters mounted thereto for installation between the jaws. The sideframe pedestals have respective pedestal seat members rockingly co-operable with the bearing adapter. The truck has members mounted intermediate the jaws and the bearing adapters for urging the bearing adapter to a centered position relative to the pedestal seat. In another aspect, there is a member for placement between the thrust lug of a railroad car sideframe pedestal jaw and the end wall and corner abutments of a bearing adapter, the member being operable to urge the bearing adapter to an at rest position relative to the sideframe. 
     In another aspect of the invention there is a sideframe pedestal to axle bearing interface assembly for a three piece rail road car truck. The interface assembly has fittings operable to rock both laterally and longitudinally, and the interface assembly includes a bearing assembly having one of the rocking surface fittings defined integrally thereon. 
     In an additional feature of that aspect of the invention the bearing assembly includes a rocking surface of compound curvature. In another feature, the fittings include rockingly matable saddle surfaces. In yet another feature, the fittings include a male surface having a first compound curvature and a mating female surface having a second compound curvature in rocking engagement with each other. One of the surfaces includes a spherical portion. In still another feature, relative to a vertical axis of rotation, rocking motion of the fittings longitudinally is torsionally de-coupled from rocking of the fittings laterally. In still yet another feature, the fittings include a force transfer interface that is torsionally compliant relative to torsional moments about a vertical axis. In a further feature, the assembly includes a resilient biasing member. 
     In an aspect of the invention there is a sideframe pedestal to axle bearing interface assembly for a three piece rail road car truck. The interface assembly has fittings operable to rock both laterally and longitudinally, and the interface assembly includes a bearing assembly having one of the rocking surface fittings defined integrally thereon. 
     In an additional feature of that aspect of the invention, the bearing assembly includes a rocking surface of compound curvature. In another feature, the fittings include rockingly matable saddle surfaces. In still another feature, the fittings include a male surface having a first compound curvature and a mating female surface having a second compound curvature in rocking engagement with each other, and one of the surfaces includes at least a spherical portion. In yet another feature, relative to a vertical axis of rotation, rocking motion of the fittings longitudinally is torsionally de-coupled from rocking of the fittings laterally. In still yet another feature, the fittings include a force transfer interface that is torsionally compliant relative to torsional moments about a vertical axis. In a further feature, the assembly includes a resilient biasing member. 
     In another aspect of the invention, there is a sideframe pedestal to axle bearing interface assembly for a three piece rail road car truck. The interface assembly has mating rocking surfaces. The assembly includes a bearing mounted to an end of a wheelset axle. The bearing has an outer ring, and one of the rocking surfaces is rigidly fixed relative to the bearing. 
     In still another aspect of the invention, there is a bearing for mounting to one end of an axle of a wheelset of a three-piece railroad car truck. The bearing has an outer member mounted in a position to permit the end of the axle to rotate relative thereto, and the outer member has a rocking surface formed thereon for engaging a mating rolling contact surface of a pedestal seat member of a sideframe of the three piece truck. In an additional feature of that aspect of the invention, the bearing has an axis of rotation coincident with a centerline axis of the axle and the surface has a region of minimum radial distance from the center of rotation and a positive derivative dr/dθ between the region and points angularly adjacent thereto on either side. 
     In another feature, the surface is cylindrical. In yet another feature, the surface has a constant radius of curvature. In still another feature, the cylinder has an axis parallel to the axis of rotation of the bearing. In still yet another feature, when installed in the three piece truck, the surface has a local minimum potential energy position, the position of minimum potential energy being located between positions of greater potential energy. In yet another feature, the surface is a surface of compound curvature. In still yet another feature, the surface has the form of a saddle. In a further feature, the surface has a radius of curvature. The bearing has an axis of rotation, and a region of minimum radial distance from the axis of rotation. The radius of curvature is greater than the minimum radial distance. 
     In yet a further feature, there is a combination of a bearing and a pedestal seat. In an additional feature, the bearing has an axis of rotation. A first location on the surface of the bearing lies radially closer to the axis of rotation than any other location thereon; a first distance, L is defined between the axis of rotation and the first location. The surface of the bearing and the surface of the pedestal seat each have a radius of curvature and mate in a male and female relationship. One radius of curvature is a male radius of curvature r 1 . The other radius of curvature is a female radius of curvature, R 2 ; r 1  being greater than L, R 2  is greater than r 1 , and L, r 1  and R 2  conform to the formula L −1 −(r 1   −1 −R 2   −1 )&gt;0. In another additional feature, the rocking surfaces are co-operable to permit self steering. 
     In still another aspect of the invention there is a three-piece railroad freight car truck. It has a bolster sprung between sideframes. The bolster is mounted to permit limited lateral travel thereof relative to the sideframes. The bolster has a first range of lateral travel relative to the sideframes when loaded under a first magnitude of vertical load, and a second, different, range of lateral travel relative to the sideframes under a second, different magnitude of vertical load. 
     In another feature, of that aspect of the invention, the second magnitude of vertical load is greater than the first magnitude, and the second range of lateral travel is greater than the first range. In a further feature, the bolster has the first range of travel in a light car condition, and the second range of travel in a fully laden car condition, the second range of travel being greater than the first range of travel. In yet another feature, the range of travel varies as a function of vertical loading of the bolster. In still another feature, the range of travel varies linearly as a function of vertical loading of the bolster. In a yet further feature, the range of travel increases linearly as a function of increasing vertical load on the bolster. In another feature, the first range permits lateral motion to either side of an at rest position through a maximum amplitude, and the maximum amplitude is in the range of ⅜ to ¾ of an inch. In another feature, the second range permits lateral motion to either side of an at rest position through a maximum amplitude, and the maximum amplitude is in the range of ⅞ to 1⅜ inches. In a still further feature, the bolster has a first end resiliently mounted to a first of the sideframes and a second end resiliently mounted to a second of the sideframes, and dampers are mounted in four-cornered groups to act between each of the bolsters ends and the sideframes respectively. In another feature, the dampers have non-metallic friction surfaces. In another feature, the truck is self-steering. In another feature, the truck has sideframe to wheelset interface fittings permitting lateral swinging motion thereof. In yet another further feature, the truck has respective four cornered, non-stick-slip groups of dampers acting between the bolster and each of the sideframes, the truck has sideframe to wheelset interface fittings permitting lateral swinging motion thereof, and the truck is a self-steering truck. In another feature, the truck has dampers acting between the bolster and each of the sideframes, and one of the dampers has a damper body and a friction member mounted to the damper body, the friction member being operably mounted to bear against a co-operating wear plate during displacement of the bolster relative to one of the sideframes, and the friction member has a mounting permitting angular displacement of the friction member about at least two axes of rotation relative to the damper body while the friction member remains in engagement with the wear plate. 
     In still another aspect of the invention, there is a railroad freight car truck having a bolster sprung between sideframes, the bolster being mounted to permit lateral travel thereof relative to the sideframes, the bolster having a range of lateral travel whose magnitude is a function of vertical displacement of the bolster. In another feature of that aspect of the invention, the range of travel is a linear function of vertical displacement of the bolster. In still another feature, the range of lateral travel of the bolster increases with increasing downward vertical displacement of the bolster relative to the sideframes. In yet another feature, the range of lateral travel of the bolster is a linear function of downward displacement of the bolster, wherein the range of lateral travel of the bolster increases in a range of proportion of between 3/16 inches and 5/16 inches of additional lateral travel for every 1 inch of additional downward deflection of the bolster at rest. 
     In another aspect of the invention, there is a three piece rail road car truck. It has sideframes mounted to a pair of wheelsets, and a bolster extending cross-wise between the sideframes. The bolster has first and second ends each resiliently mounted to a respective one of the sideframes. The bolster has gibs. The sideframes have stops positioned to oppose the gibs. Mating pairs of respective ones of the gibs and the stops are co-operatively engageable to limit transverse displacement of the bolster relative to the sideframes. The bolster has a first at rest position relative to the sideframes under a first vertical loading condition, and a second at rest position relative to the sideframes under a second, different, vertical loading condition. In the first at rest position of the bolster there being a first gap distance between a first bolster gib and its paired stop. In the second at rest position of the bolster there is a second, different, gap distance between that same first bolster gib and its paired stop. 
     In another feature of that aspect of the invention, the sideframes are mounted to the wheelsets at respective sideframe to wheelset interface fittings, and those fittings include rocker members permitting the sideframes to swing laterally. In another feature, the truck has a four cornered arrangement of dampers mounted to act between each of the sideframes and a respective one of the ends of the bolster. In another feature, the first bolster gib has an abutment surface for mating its paired stop, and the abutment surface is not confined to a vertical plane. In another feature, the bolster gib has an abutment surface for mating with its paired stop, the abutment surface being inclined with respect to vertical. In another feature, the paired stop of the first bolster gib has an abutment surface for engaging the first bolster gib, and the abutment surface is not confined to a vertical plane. In another feature, the paired stop of the first bolster gib has an abutment surface for engaging the first bolster gib, and the abutment surface is inclined with respect to vertical. In another feature, the first bolster gib and its paired stop having mating abutment surfaces for limiting lateral travel of the bolster, the mating abutment surfaces being inclined with respect to vertical. In another feature, the outboard bolster gib is inclined with respect to vertical. In another feature, both the inboard bolster gib and the outboard bolster gib are tapered with respect to vertical. 
     In still another aspect of the invention, there is a damper assembly for installation between a truck bolster and a sideframe of a three piece railroad car truck. The damper assembly has a damper body and a friction member mountable to the damper body, the damper body is seatable in a bolster pocket and is engageable by a damper biasing member. The friction member having a friction surface for engagement with a wear plate; and the friction member having at least two rotational degrees of freedom relative to the damper body when mounted thereto. 
     In another feature of that aspect of the invention, the damper body and the friction member have mutually engaging arcuate surfaces, those surfaces being formed on a body of revolution. In another feature, the damper body and the friction member have mutually engaging arcuate surfaces, those surfaces being formed on a spherical arc. In another feature, the mutually engaging surfaced are in a non-rocking relationship. In another feature, the surfaces are mounted in a sliding relationship. In another feature, the body includes members for engaging a biasing member. In another feature, the body includes a sloped face for seating against an inclined face of a damper pocket, and the slope face is free of a crown. In another feature, the friction member includes a first portion for engagement with the damper body, and a second portion for engagement with a wear plate, and the second portion is made from a different material than the first portion. In another feature, the surface of the friction member is formed on a bulging portion thereof, and the damper body includes a cavity for accommodating the bulging portion of the friction member. In another feature, the friction surface has a circular footprint. 
     These and other aspects and features of the invention may be understood with reference to the detailed descriptions of the invention and the accompanying illustrations as set forth below. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The principles of the invention may better be understood with reference to the accompanying figures provided by way of illustration of an exemplary embodiment, or embodiments, incorporating principles and aspects of the present invention, and in which: 
         FIG. 1   a  shows an isometric view of an example of an embodiment of a railroad car truck; 
         FIG. 1   b  shows a top view of the railroad car truck of  FIG. 1   a;    
         FIG. 1   c  shows a side view of the railroad car truck of  FIG. 1   a;    
         FIG. 1   d  shows an exploded view of a portion of a truck similar to that of  FIG. 1   a;    
         FIG. 1   e  is an exploded, sectioned view of an example of an alternate three piece truck to that of  FIG. 1   a , having dampers mounted along the spring group centerlines; 
         FIG. 1   f  shows an isometric view of an example of an alternate railroad car truck according to that of  FIG. 1   a;    
         FIG. 1   g  shows a side view of the railroad car truck of  FIG. 1   f;    
         FIG. 1   h  shows a top view of the railroad car truck of  FIG. 1   f;    
         FIG. 1   i  is a split view showing, in one half an end view of the truck of  FIG. 1   f , and in the other half and a section taken level with the truck center; 
         FIG. 1   j  shows a spring layout for the truck of  FIG. 1   f;    
         FIG. 2   a  is an enlarged detail of a side view of a truck such as the truck of  FIG. 1   a ,  1   b ,  1   c  or  1   e  taken at the sideframe pedestal to bearing adapter interface; 
         FIG. 2   b  shows a lateral cross-section through the sideframe pedestal to bearing interface of  FIG. 2   a , taken at the wheelset axle centerline; 
         FIG. 2   c  shows the cross-section of  FIG. 2   b  in a laterally deflected condition; 
         FIG. 2   d  is a longitudinal section of the pedestal seat to bearing adapter interface of  FIG. 2   a , on the longitudinal plane of symmetry of the bearing adapter; 
         FIG. 2   e  shows the longitudinal section of  FIG. 2   d  as longitudinally deflected; 
         FIG. 2   f  shows a top view of the detail of  FIG. 2   a;    
         FIG. 2   g  shows a staggered section of the bearing adapter of  FIG. 2   a , on section lines ‘ 2   g - 2   g ’ of  FIG. 2   a;    
         FIG. 3   a  shows an exploded isometric view of an alternate sideframe pedestal to bearing adapter interface to that of  FIG. 2   a;    
         FIG. 3   b  shows an alternate bearing adapter to pedestal seat interface to that of  FIG. 3   a;    
         FIG. 3   c  shows a sectional view of the assembly of  FIG. 3   b ; taken on a longitudinal-vertical plane of symmetry thereof; 
         FIG. 3   d  shows a stepped sectional view of a detail of the assembly of  FIG. 3   b  taken on  3   d - 3   d ′ of  FIG. 3   c;    
         FIG. 3   e  shows an exploded view of another alternative embodiment of bearing adapter to pedestal seat interface to that of  FIG. 3   a;    
         FIG. 4   a  shows an isometric view of a retainer pad of the assembly of  FIG. 3   a , taken from above, and in front of one corner; 
         FIG. 4   b  is an isometric view from above and behind the retainer pad of  FIG. 4   a;    
         FIG. 4   c  is a bottom view of the retainer pad of  FIG. 4   a;    
         FIG. 4   d  is a front view of the retainer pad of  FIG. 4   a;    
         FIG. 4   e  is a section on ‘ 4   e - 4   e ’ of  FIG. 4   d  of the retainer pad of  FIG. 4   a;    
         FIG. 5  shows an alternate bolster, similar to that of  FIG. 1   d , with a pair of spaced apart bolster pockets, and inserts with primary and secondary wedge angles; 
         FIG. 6   a  is a cross-section of an alternate damper such as may be used, for example, in the bolster of the trucks of  FIGS. 1   a ,  1   b ,  1   c ,  1   d  and  1   f;    
         FIG. 6   b  shows the damper of  FIG. 6   a  with friction modifying pads removed; 
         FIG. 6   c  is a reverse view of a friction modifying pad of the damper of  FIG. 6   a;    
         FIG. 7   a  is a front view of a friction damper for a truck such as that of  FIG. 1   a;    
         FIG. 7   b  shows a side view of the damper of  FIG. 7   a;    
         FIG. 7   c  shows a rear view of the damper of  FIG. 7   b;    
         FIG. 7   d  shows a top view of the damper of  FIG. 7   a;    
         FIG. 7   e  shows a cross-sectional view on the centerline of the damper of  FIG. 7   a  taken on section ‘ 7   e - 7   e ’ of  FIG. 7   c;    
         FIG. 7   f  is a cross-section of the damper of  FIG. 7   a  taken on section ‘ 7   f - 7   f ’ of  FIG. 7   e;    
         FIG. 7   g  shows an isometric view of an alternate damper to that of  FIG. 7   a  having a friction modifying side face pad; 
         FIG. 7   h  shows an isometric view of a further alternate damper to that of  FIG. 7   a , having a “wrap-around” friction modifying pad; 
         FIG. 8   a  shows an exploded isometric installation view of an alternate bearing adapter assembly to that of  FIG. 3   a;    
         FIG. 8   b  shows an isometric, assembled view of the bearing adapter assembly of  FIG. 8   a;    
         FIG. 8   c  shows the assembly of  FIG. 8   b  with a rocker member thereof removed; 
         FIG. 8   d  shows the assembly of  FIG. 8   b , as installed, in longitudinal cross-section; 
         FIG. 8   e  is an installed view of the assembly of  FIG. 8   b , on section ‘ 8   e - 8   e ’ of  FIG. 8   d;    
         FIG. 8   f  shows the assembly of  FIG. 8   b , as installed, in lateral cross section; 
         FIG. 9   a  shows an exploded isometric view of an alternate assembly to that of  FIG. 3   a;    
         FIG. 9   b  shows an exploded isometric view similar to the view of  FIG. 9   a , showing a bearing adapter assembly incorporating an elastomeric pad; 
         FIG. 10   a  shows an exploded isometric view of an alternate assembly to that of  FIG. 3   a;    
         FIG. 10   b  shows a perspective view of a bearing adapter of the assembly of  FIG. 10   a  from above and to one corner; 
         FIG. 10   c  shows a perspective of the bearing adapter of  FIG. 10   b  from below; 
         FIG. 10   d  shows a bottom view of the bearing adapter of  FIG. 10   b;    
         FIG. 10   e  shows a longitudinal section of the bearing adapter of  FIG. 10   b  taken on section ‘ 10   e - 10   e ’ of  FIG. 10   d ; and 
         FIG. 10   f  shows a transverse section of the bearing adapter of  FIG. 10   b  taken on section ‘ 10   f - 10   f ’ of  FIG. 10   d;    
         FIG. 11   a  is an exploded view of an alternate bearing adapter assembly to that of  FIG. 3   a;    
         FIG. 11   b  shows a view of the bearing adapter of  FIG. 11   a  from below and to one corner; 
         FIG. 11   c  is a top view of the bearing adapter of  FIG. 11   b;    
         FIG. 11   d  is a lengthwise section of the bearing adapter of  FIG. 11   c  on ‘ 11   d - 11   d’;    
         FIG. 11   e  is a cross-wise section of the bearing adapter of  FIG. 11   c  on ‘ 11   e - 11   e ’; and 
         FIG. 11   f  is a set of views of a resilient pad member of the assembly of  FIG. 11   a;    
         FIG. 11   g  shows a view of the bearing adapter of  FIG. 11   a  from above and to one corner; 
         FIG. 12   a  shows an exploded isometric view of an alternate bearing adapter to pedestal seat assembly to that of  FIG. 3   a;    
         FIG. 12   b  shows a longitudinal central section of the assembly of  FIG. 12   a , as assembled; 
         FIG. 12   c  shows a section on ‘ 12   c - 12   c ’ of  FIG. 12   b ; and 
         FIG. 12   d  shows a section on ‘ 12   d - 12   d ’ of  FIG. 12   b;    
         FIG. 13   a  shows a top view of an embodiment of bearing adapter and pedestal seat such as could be used in a side frame pedestal similar to that of  FIG. 2   a , with the seat inverted to reveal a female depression formed therein for engagement with the bearing adapter; 
         FIG. 13   b  shows a side view of the bearing adapter and seat of  FIG. 13   a;    
         FIG. 13   c  shows a longitudinal section of the bearing adapter of  FIG. 13   a  taken on section ‘ 13   c - 13   c ’ of  FIG. 13   d;    
         FIG. 13   d  shows an end view of the bearing adapter and pedestal seat of  FIG. 13   a;    
         FIG. 13   e  shows a transverse section of the bearing adapter of  FIG. 13   a , taken on the wheelset axle centerline; 
         FIG. 13   f  is a section in the transverse plane of symmetry of a bearing adapter and pedestal seat pair like that of  FIG. 13   e , with inverted rocker and seat portions; 
         FIG. 13   g  shows a cross-section on the longitudinal plane of symmetry of the bearing adapter and pedestal seat pair of  FIG. 13   f;    
         FIG. 14   a  shows an isometric view of an alternate embodiment of bearing adapter and pedestal seat to that of  FIG. 13   a  having a fully curved upper surface; 
         FIG. 14   b  shows a side view of the bearing adapter and seat of  FIG. 14   a;    
         FIG. 14   c  shows an end view of the bearing adapter and seat of  FIG. 14   a;    
         FIG. 14   d  shows a cross-section of the bearing adapter and pedestal seat of  FIG. 14   a  taken on the longitudinal plane of symmetry; 
         FIG. 14   e  shows a cross-section of the bearing adapter and pedestal seat of  FIG. 14   a  taken on the transverse plane of symmetry; 
         FIG. 15   a  shows a top view of an alternate bearing adapter and an inverted view of an alternate female pedestal seat to that of  FIG. 13   a;    
         FIG. 15   b  shows a longitudinal section of the bearing adapter of  FIG. 15   a;    
         FIG. 15   c  shows an end view of the bearing adapter and seat of  FIG. 15   a;    
         FIG. 16   a  shows an isometric view of a further embodiment of bearing adapter and seat combination to that of  FIG. 13   a , in which the bearing adapter and pedestal seat have saddle shaped engagement interfaces; 
         FIG. 16   b  shows an end view of the bearing adapter and pedestal seat of  FIG. 16   a;    
         FIG. 16   c  shows a side view of the bearing adapter and pedestal seat of  FIG. 16   a;    
         FIG. 16   d  is a lateral section of the adapter and pedestal seat of  FIG. 16   a;    
         FIG. 16   e  is a longitudinal section of the adapter and pedestal seat of  FIG. 16   a;    
         FIG. 16   f  shows a transverse cross section of a bearing adapter and pedestal seat pair having an inverted interface to that of  FIG. 16   a;    
         FIG. 16   g  shows a longitudinal cross section for the bearing adapter and pedestal seat pair of  FIG. 16   f;    
         FIG. 17   a  shows an exploded side view of a further alternate bearing adapter and seat combination to that of  FIG. 13   a , having a pair of cylindrical rocker elements, and a pivoted connection therebetween; 
         FIG. 17   b  shows an exploded end view of the bearing adapter and seat of  FIG. 17   a;    
         FIG. 17   c  shows a cross-section of the bearing adapter and seat of  FIG. 17   a , as assembled, taken on the longitudinal centerline thereof; 
         FIG. 17   d  shows a cross-section of the bearing adapter and seat of  FIG. 17   a , as assembled, taken on the transverse centerline thereof; 
         FIG. 17   e  shows possible permutations of the assembly of  FIG. 17   a;    
         FIG. 18   a  is an exploded end view of an alternate version of bearing adapter and seat assembly to that of  FIG. 17   a  having an elastomeric intermediate member; 
         FIG. 18   b  shows an exploded side view of the assembly of  FIG. 18   a;    
         FIG. 19   a  is a side view of alternate assembly to that of  FIG. 13   a  or  16   a , employing an elastomeric shear pad and a laterally swinging rocker; 
         FIG. 19   b  shows a transverse cross-section of the assembly of  FIG. 19   a , taken on the axle center line thereof; 
         FIG. 19   c  shows a cross section of the assembly of  FIG. 19   a  taken on the longitudinal plane of symmetry of the bearing adapter; 
         FIG. 19   d  shows a sectional view of the alternate assembly of  FIG. 19   a , as viewed from above, taken on the staggered section indicated as ‘ 19   d - 19   d’;    
         FIG. 19   e  shows an end view of an alternate rocker combination to that of  FIG. 19   a  employing an elastomeric pad; 
         FIG. 19   f  shows a perspective view of the alternate pad combination of  FIG. 19   e;    
         FIG. 20   a  is a view of a bearing adapter for use in the assembly of  FIG. 19   a;    
         FIG. 20   b  shows a top view of the bearing adapter of  FIG. 20   a;    
         FIG. 20   c  shows a longitudinal cross-section of the bearing adapter of  FIG. 20   a;    
         FIG. 21   a  shows an isometric view of a pad adapter for the assembly of  FIG. 19   a;    
         FIG. 21   b  shows a top view of the pad adapter of  FIG. 21   a;    
         FIG. 21   c  shows a side view of the pad adapter of  FIG. 21   a;    
         FIG. 21   d  shows a half cross-section of the pad adapter of  FIG. 21   a;    
         FIG. 21   e  shows an isometric view of a rocker for the pad adapter of  FIG. 21   a;    
         FIG. 21   f  shows a top view of the rocker of  FIG. 21   a;    
         FIG. 21   g  shows an end view of the rocker of  FIG. 21   a;    
         FIG. 22   a  shows an end view of an alternate arrangement of wheelset to pedestal interface assembly arrangement to that of  FIG. 2   a , having mating bi-directionally arcuate rocking members, one being formed integrally as an outer portion of a bearing; 
         FIG. 22   b  shows a cross-section of the assembly of  FIG. 22   a  taken on ‘ 22   b - 22   b ’ of  FIG. 22   a;    
         FIG. 22   c  shows a cross-section of the assembly of  FIG. 22   a  as viewed in the direction of arrows ‘ 22   c - 22   c ’ of  FIG. 22   b;    
         FIG. 23   a  shows an end view of an alternate assembly to that of  FIG. 22   a  incorporating a uni-directionally fore-and-aft rocking member; 
         FIG. 23   b  shows a cross-sectional view taken on ‘ 23   b - 23   b ’ of  FIG. 23   a;    
         FIG. 24   a  shows an isometric view of an alternate three piece truck to that of  FIG. 1   a;    
         FIG. 24   b  shows a side view of the three piece truck of  FIG. 24   a;    
         FIG. 24   c  shows a top view of half of the three piece truck of  FIG. 24   b;    
         FIG. 24   d  shows a partial section of the truck of  FIG. 24   b  taken on ‘ 24   d - 24   d’;    
         FIG. 24   e  shows a partial isometric view of the truck bolster of the three piece truck of  FIG. 24   a  showing friction damper seats; 
         FIG. 24   f  shows a force schematic for four cornered damper arrangements generally, such as, for example, in the trucks of  FIGS. 1   a ,  1   f , and  FIG. 24   a;    
         FIG. 25   a  shows a side view of an alternate three piece truck to that of  FIG. 24   a;    
         FIG. 25   b  shows a top view of half of the three piece truck of  FIG. 25   a;    
         FIG. 25   c  shows a partial section of the truck of  FIG. 25   a  taken on ‘ 25   c - 25   c’;    
         FIG. 25   d  shows an exploded isometric view of the bolster and side frame assembly of  FIG. 25   a , in which horizontally acting springs drive constant force dampers; 
         FIG. 26   a  shows an alternate version of the bolster of  FIG. 24   e , with a double sized damper pocket for seating a large single wedge having a welded insert; 
         FIG. 26   b  shows an alternate dual wedge for a truck bolster like that of  FIG. 26   a;    
         FIG. 27   a  shows an alternate bolster arrangement similar to that of  FIG. 5 , but having split wedges; 
         FIG. 27   b  shows a bolster similar to that of  FIG. 24   a , having a wedge pocket having primary and secondary angles and a split wedge arrangement for use therewith; 
         FIG. 27   c  shows an alternate stepped single wedge for the bolster of  FIG. 27   b;    
         FIG. 28   a  shows an alternate bolster and wedge arrangement to that of  FIG. 17   b , having secondary wedge angles; 
         FIG. 28   b  shows an alternate, split wedge arrangement for the bolster of  FIG. 28   a;    
         FIG. 29   a  shows a 3 dimensional view of a section through a sideframe of an embodiment of a truck such as shown in  FIG. 1   a ,  1   f , or  1   i  showing a tapered gib arrangement; 
         FIG. 29   b  shows an orthogonal view of the gib arrangement of  FIG. 29   a  looking parallel to the long axis of the sideframe in a light c-condition; 
         FIG. 29   c  shows the gib arrangement of  FIG. 29   b  in a laded condition; 
         FIG. 29   d  shows a top view of the gib arrangement of  FIG. 29   a;    
         FIG. 29   e  shows an alternate gib arrangement to that of  FIG. 29   b , having tapered inboard and outboard gibs; 
         FIG. 29   f  shows another alternate gib arrangement to that of  FIG. 29   b;    
         FIG. 30   a  shows an exploded three-dimensional view of an alternate damper assembly such as may be used in the truck of  FIG. 1   a , or other trucks herein; 
         FIG. 30   b  shows an isometric view of the damper assembly of  FIG. 30   a  from in front, above, and to one corner; 
         FIG. 30   c  shows an opposite isometric view of the damper assembly of  FIG. 30   b;    
         FIG. 30   d  shows a front view of the damper assembly of  FIG. 30   a;    
         FIG. 30   e  shows a rear view of the damper assembly of  FIG. 30   a;    
         FIG. 30   f  shows a bottom view of the damper assembly of  FIG. 30   a ; and 
         FIG. 30   g  shows a mid-sectional view on a vertical plane ‘ 30   g - 30   g ’ of the damper assembly of  FIG. 30   e.    
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The description that follows, and the embodiments described therein, are provided by way of illustration of an example, or examples, of particular embodiments of the principles of aspects of the present invention. These examples are provided for the purposes of explanation, and not of limitation, of those principles and of the invention. In the description, like parts are marked throughout the specification and the drawings with the same respective reference numerals. The drawings are not necessarily to scale and in some instances proportions may have been exaggerated in order more clearly to depict certain features of the invention. 
     In terms of general orientation and directional nomenclature, for each of the rail road car trucks described herein, the longitudinal direction is defined as being coincident with the rolling direction of the rail road car, or rail road car unit, when located on tangent (that is, straight) track. In the case of a rail road car having a center sill, the longitudinal direction is parallel to the center sill, and parallel to the side sills, if any. Unless otherwise noted, vertical, or upward and downward, are terms that use top of rail, TOR, as a datum. The term lateral, or laterally outboard, refers to a distance or orientation relative to the longitudinal centerline of the railroad car, or car unit. The term “longitudinally inboard”, or “longitudinally outboard” is a distance taken relative to a mid-span lateral section of the car, or car unit. Pitching motion is angular motion of a railcar unit about a horizontal axis perpendicular to the longitudinal direction. Yawing is angular motion about a vertical axis. Roll is angular motion about the longitudinal axis. 
     This description relates to rail car trucks and truck components. Several AAR standard truck sizes are listed at page 711 in the 1997 Car &amp; Locomotive Cyclopedia. As indicated, for a single unit rail car having two trucks, a “40 Ton” truck rating corresponds to a maximum gross car weight on rail (GRL) of 142,000 lbs. Similarly, “50 Ton” corresponds to 177,000 lbs., “70 Ton” corresponds to 220,000 lbs., “100 Ton” corresponds to 263,000 lbs., and “125 Ton” corresponds to 315,000 lbs. In each case the load limit per truck is then half the maximum gross car weight on rail. Two other types of truck are the “110 Ton” truck for railcars having a 286,000 lbs. GRL and the “70 Ton Special” low profile truck sometimes used for auto rack cars. Given that the rail road car trucks described herein tend to have both longitudinal and transverse axes of symmetry, a description of one half of an assembly may generally also be intended to describe the other half as well, allowing for differences between right hand and left hand parts. 
     This description refers to friction dampers for rail road car trucks, and multiple friction damper systems. There are several types of damper arrangements, some being shown at pp. 715-716 of the 1997 Car and Locomotive Cyclopedia, those pages being incorporated herein by reference. Each of the arrangements of dampers shown at pp. 715 to 716 of the 1997 Car and Locomotive Cyclopedia can be modified to employ a four cornered, double damper arrangement of inner and outer dampers. 
     In terms of general nomenclature, damper wedges tend to be mounted within an angled “bolster pocket” formed in an end of the truck bolster. In cross-section, each wedge may then have a generally triangular shape, one side of the triangle being, or having, a bearing face, a second side which might be termed the bottom, or base, forming a spring seat, and the third side being a sloped side or hypotenuse between the other two sides. The first side may tend to have a substantially planar bearing face for vertical sliding engagement against an opposed bearing face of one of the sideframe columns. The second face may not be a face, as such, but rather may have the form of a socket for receiving the upper end of one of the springs of a spring group. Although the third face, or hypotenuse, may appear to be generally planar, it may tend to have a slight crown, having a radius of curvature of perhaps 60″. The crown may extend along the slope and may also extend across the slope. The end faces of the wedges may be generally flat, and may have a coating, surface treatment, shim, or low friction pad to give a smooth sliding engagement with the sides of the bolster pocket, or with the adjacent side of another independently slidable damper wedge, as may be. 
     During railcar operation, the sideframe may tend to rotate, or pivot, through a small range of angular deflection about the end of the truck bolster to yield wheel load equalization. The slight crown on the slope face of the damper may tend to accommodate this pivoting motion by allowing the damper to rock somewhat relative to the generally inclined face of the bolster pocket while the planar bearing face remains in planar contact with the wear plate of the sideframe column. Although the slope face may have a slight crown, for the purposes of this description it will be described as the slope face or as the hypotenuse, and will be considered to be a substantially flat face as a general approximation. 
     In the terminology herein, wedges have a primary angle α, being the included angle between (a) the sloped damper pocket face mounted to the truck bolster, and (b) the side frame column face, as seen looking from the end of the bolster toward the truck center. In some embodiments, a secondary angle may be defined in the plane of angle α, namely a plane perpendicular to the vertical longitudinal plane of the (undeflected) side frame, tilted from the vertical at the primary angle. That is, this plane is parallel to the (undeflected) long axis of the truck bolster, and taken as if sighting along the back side (hypotenuse) of the damper. The secondary angle β is defined as the lateral rake angle seen when looking at the damper parallel to the plane of angle α. As the suspension works in response to track perturbations, the wedge forces acting on the secondary angle β may tend to urge the damper either inboard or outboard according to the angle chosen. 
     General Description of Truck Features 
       FIGS. 1   a  and  1   f  provide examples of trucks  20  and  22  may have the same, or generally similar, features and similar construction, although they may differ in pendulum length, spring stiffness, wheelbase, window width and height, and damping arrangement. That is, truck  20  of  FIG. 1   f  may tend to have a longer wheelbase (from 73 inches to 86 inches, possibly between 80-84 inches for truck  20 , as opposed to a wheelbase of 63-73 inches for truck  22 ), may tend to have a main spring group having a softer vertical spring rate, and a four cornered damper group that may have different primary and secondary angles on the damper wedges. Truck  20  may have a 5×3 spring group arrangement, while truck  22  may have a 3×3 arrangement. While either truck may be suitable for a variety of general purpose uses, truck  20  may be optimized for carrying relatively low density, high value lading, such as automobiles or consumer products, for example, whereas truck  22  may be optimized for carrying denser semi-finished industrial goods, such as might be carried in rail road freight cars for transporting rolls of paper. The various features of the two truck types may be interchanged, and are intended to be illustrative of a wide range of truck types. Notwithstanding possible differences in size, generally similar features are given the same part numbers. Trucks  20  and  22  are symmetrical about both their longitudinal and transverse, or lateral, centerline axes. In each case, where reference is made to a sideframe, it will be understood that the truck has first and second sideframes, first and second spring groups, and so on. 
     Trucks  20  and  22  each have a truck bolster  24  and sideframes  26 . Each sideframe  26  has a generally rectangular window  28  that accommodates one of the ends  30  of the bolster  24 . The upper boundary of window  28  is defined by the sideframe arch, or compression member identified as top chord member  32 , and the bottom of window  28  is defined by a tension member identified as bottom chord  34 . The fore and aft vertical sides of window  28  are defined by sideframe columns  36 . The ends of the tension member sweep up to meet the compression member. At each of the swept-up ends of sideframe  26  there are sideframe pedestal fittings, or pedestal seats  38 . Each fitting  38  accommodates an upper fitting, which may be a rocker or a seat, as described and discussed below. This upper fitting, whichever it may be, is indicated generically as  40 . Fitting  40  engages a mating fitting  42  of the upper surface of a bearing adapter  44 . Bearing adapter  44  engages a bearing  46  mounted on one of the ends of one of the axles  48  of the truck adjacent one of the wheels  50 . A fitting  40  is located in each of the fore and aft pedestal fittings  38 , the fittings  40  being longitudinally aligned so the sideframe can swing sideways relative to the truck&#39;s rolling direction. 
     The relationship of the mating fittings  40  and  42  is described at greater length below. The relationship of these fittings determines part of the overall relationship between an end of one of the axles of one of the wheelsets and the sideframe pedestal. That is, in determining the overall response, the degrees of freedom of the mounting of the axle end in the sideframe pedestal involve a dynamic interface across an assembly of parts, such as may be termed a wheelset to sideframe interface assembly, that may include the bearing, the bearing adapter, an elastomeric pad, if used, a rocker if used, and the pedestal seat mounted in the roof of the sideframe pedestal. Several different embodiments of this wheelset to sideframe interface assembly are described below. To the extent that bearing  46  has a single degree of freedom, namely rotation about the wheelshaft axis, analysis of the assembly can be focused on the bearing to pedestal seat interface assembly, or on the bearing adapter to pedestal seat interface assembly. For the purposes of this description, items  40  and  42  are intended generically to represent the combination of features of a bearing adapter and pedestal seat assembly defining the interface between the roof of the sideframe pedestal and the bearing adapter, and the six degrees of freedom of motion at that interface, namely vertical, longitudinal and transverse translation (i.e., translation in the z, x, and y directions) and pitching, rolling, and yawing (i.e., rotational motion about the y, x, and z axes respectively) in response to dynamic inputs. 
     The bottom chord or tension member of sideframe  26  may have a basket plate, or lower spring seat  52  rigidly mounted thereto. Although trucks  20  and  22  may be free of unsprung lateral cross-bracing, whether in the nature of a transom or lateral rods, in the event that truck  20  or  22  is taken to represent a “swing motion” truck with a transom or other cross bracing, the lower rocker platform of spring seat  52  may be mounted on a rocker, to permit lateral rocking relative to sideframe  26 . Spring seat  52  may have retainers for engaging the springs  54  of a spring set, or spring group,  56 , whether internal bosses, or a peripheral lip for discouraging the escape of the bottom ends of the springs. The spring group, or spring set  56 , is captured between the distal end  30  of bolster  24  and spring seat  52 , being placed under compression by the weight of the rail car body and lading that bears upon bolster  24  from above. 
     Bolster  24  has double, inboard and outboard, bolster pockets  60 ,  62  on each face of the bolster at the outboard end (i.e., for a total of 8 bolster pockets per bolster, 4 at each end). Bolster pockets  60 ,  62  accommodate fore and aft pairs of first and second, laterally inboard and laterally outboard friction damper wedges  64 ,  66  and  68 ,  70 , respectively. Each bolster pocket  60 ,  62  has an inclined face, or damper seat  72 , that mates with a similarly inclined hypotenuse face  74  of the damper wedge,  64 ,  66 ,  68  and  70 . Wedges  64 ,  66  each sit over a first, inboard corner spring  76 ,  78 , and wedges  68 ,  70  each sit over a second, outboard corner spring  80 ,  82 . Angled faces  74  of wedges  64 ,  66  and  68 ,  70  ride against the angled faces of respective seats  72 . 
     A middle end spring  96  bears on the underside of a land  98  located intermediate bolster pockets  60  and  62 . The top ends of the central row of springs,  100 , seat under the main central portion  102  of the end of bolster  24 . In this four corner arrangement, each damper is individually sprung by one or another of the springs in the spring group. The static compression of the springs under the weight of the car body and lading tends to act as a spring loading to bias the damper to act along the slope of the bolster pocket to force the friction surface against the sideframe. Friction damping is provided when the vertical sliding faces  90  of the friction damper wedges  64 ,  66  and  68 ,  70  ride up and down on friction wear plates  92  mounted to the inwardly facing surfaces of sideframe columns  36 . In this way the kinetic energy of the motion is, in some measure, converted through friction to heat. This friction may tend to damp out the motion of the bolster relative to the sideframes. When a lateral perturbation is passed to wheels  50  by the rails, rigid axles  48  may tend to cause both sideframes  26  to deflect in the same direction. The reaction of sideframes  26  is to swing, like pendula, on the upper rockers. The weight of the pendulum and the reactive force arising from the twisting of the springs may then tend to urge the sideframes back to their initial position. The tendency to oscillate harmonically due to track perturbations may tend to be damped out by the friction of the dampers on the wear plates  92 . 
     As compared to a bolster with single dampers, such as may be mounted on the sideframe centerline as shown in  FIG. 1   e , for example, the use of doubled dampers such as spaced apart pairs of dampers  64 ,  68  may tend to give a larger moment arm, as indicated by dimension “2M” in  FIG. 1   d , for resisting parallelogram deformation of truck  22  more generally. Use of doubled dampers may yield a greater restorative “squaring” force to return the truck to a square orientation than for a single damper alone with the restorative bias, namely the squaring force, increasing with increasing deflection. That is, in parallelogram deformation, or lozenging, the differential compression of one diagonal pair of springs (e.g., inboard spring  76  and outboard spring  82  may be more pronouncedly compressed) relative to the other diagonal pair of springs (e.g., inboard spring  78  and outboard spring  80  may be less pronouncedly compressed than springs  76  and  82 ) tends to yield a restorative moment couple acting on the sideframe wear plates. This moment couple tends to rotate the sideframe in a direction to square the truck, (that is, in a position in which the bolster is perpendicular, or “square”, to the sideframes). As such, the truck is able to flex, and when it flexes the dampers co-operate in acting as biased members working between the bolster and the side frames to resist parallelogram, or lozenging, deformation of the side frame relative to the truck bolster and to urge the truck back to the non-deflected position. 
     The foregoing explanation has been given in the context of trucks  20  and  22 , each of which has a spring group that has three rows facing the sideframe columns. The restorative moment couple of a four-cornered damper layout can also be explained in the context of a truck having a 2 row spring group arrangement facing the dampers, as in truck  400  of  FIGS. 14   a  to  14   e . For the purposes of conceptual visualization, the normal force on the friction face of any of the dampers can be taken as a pressure field whose effect can be approximated by a point load acting at the centroid of the pressure field and whose magnitude is equal to the integrated value of the pressure field over its area. The center of this distributed force, acting on the inboard friction face of wedge  440  against column  428  can be thought of as a point load offset transversely relative to the diagonally outboard friction face of wedge  443  against column  430  by a distance that is nominally twice dimension  1 ′ shown in the conceptual sketch of  FIG. 1   k . In the example of  FIG. 14   a , this distance, 2 L, is about one full diameter of the large spring coils in the spring set. The restoring moment in such a case would be, conceptually, M R =[(F 1 +F 3 )−(F 2 +F 4 )]L. This may be expressed M R =4k c  Tan(ε) Tan(θ)L, where θ is the primary angle of the damper (generally illustrated as α herein), and k c  is the vertical spring constant of the coil upon which the damper sits and is biased. 
     In the various arrangements of spring groups 2×4, 3×3, 3:2:3 or 3×5 group, dampers may be mounted over each of four corner positions. The portion of spring force acting under the damper wedges may be in the 25-50% range for springs of equal stiffness. If not of equal stiffness, the portion of spring force acting under the dampers may be in the range of perhaps 20% to 35%. The coil groups can be of unequal stiffness if inner coils are used in some springs and not in others, or if springs of differing spring constant are used. 
     An enhanced tendency to encourage squareness at the bolster to sideframe interface (i.e., through the use of four cornered damper groups) may tend to reduce reliance on squareness at the pedestal to wheelset axle interface, and turn, may tend to provide an opportunity to employ a torsionally compliant (about the vertical axis) axle to pedestal interface assembly, and to permit a measure of self steering. 
     The bearing plate, namely wear plate  92  ( FIG. 1   a ) is significantly wider than the through thickness of the sideframes more generally, as measured, for example, at the pedestals, and may tend to be wider than has been conventionally common. This additional width corresponds to the additional overall damper span width measured fully across the damper pairs, plus lateral travel as noted above, typically allowing 1½ (+/−) inches of lateral travel of the bolster relative to the sideframe to either side of the undeflected central position. That is, rather than having the width of one coil, plus allowance for travel, plate  92  may have the width of three coils, plus allowance to accommodate 1½ (+/−) inches of travel to either side for a total, double amplitude travel of 3″ (+/−). Bolster  24  has inboard and outboard gibs  106 ,  108  respectively, that bound the lateral motion of bolster  24  relative to sideframe columns  36 . This motion allowance may be in the range of +/−1⅛ to 1¾ in., and may be in the range of 1 3/16 to 1 9/16 in., and can be set, for example, at 1½ in. or 1¼ in. of lateral travel to either side of a neutral, or centered, position when the sideframe is undeflected. 
     The lower ends of the springs of the entire spring group, identified generally as  58 , seat in lower spring seat  52 . Lower spring seat  52  may be laid out as a tray with an upturned rectangular peripheral lip. Although truck  22  employs a spring group in a 3×3 arrangement, this is intended to be generic, and to represent a range of variations. They may represent 3×5, 2×4, 3:2:3 or 2:3:2 arrangement, or some other, and may include a hydraulic snubber, or such other arrangement of springs may be appropriate for the given service for the railcar for which the truck is intended. 
       FIGS. 2   a - 2   g    
     The rocking interface surface of the bearing adapter might have a crown, or a concave curvature, like a swing motion truck, by which a rolling contact on the rocker permits lateral swinging of the side frame. The bearing adapter to pedestal seat interface might also have a fore-and-aft curvature, whether a crown or a depression, and that, for a given vertical load, this crown or depression might tend to present a more or less linear resistance to deflection in the longitudinal direction, much as a spring or elastomeric pad might do. 
     For surfaces in rolling contact on a compound curved surface (i.e., having curvatures in two directions) as shown and described herein, the vertical stiffness may be approximated as infinite (i.e. very large as compared to other stiffnesses); the longitudinal stiffness in translation at the point of contact can also be taken as infinite, the assumption being that the surfaces do not slip; the lateral stiffness in translation at the point of contact can be taken as infinite, again, provided the surfaces do not slip. The rotational stiffness about the vertical axis may be taken as zero or approximately zero. By contrast, the angular stiffnesses about the longitudinal and transverse axes are non-trivial. The lateral angular stiffnesses may tend to determine the equivalent pendulum stiffnesses for the sideframe more generally. 
     The stiffness of a pendulum is directly proportional to the weight on the pendulum. Similarly, the drag on a rail car wheel, and the wear to the underlying track structure, is a function of the weight borne by the wheel. For this reason, the desirability of self steering may be greatest for a fully laden car, and a pendulum may tend to maintain a general proportionality between the weight borne by the wheel and the stiffness of the self-steering mechanism as the lading increases. 
     Truck performance may vary with the friction characteristics of the damper surfaces. Wedges have been used that have tended to employ dampers in which the dynamic and static coefficients of friction may have been significantly different, yielding a stick-slip phenomenon that may not have been entirely advantageous. In some embodiments herein the feature of a self-steering capability may be combined with dampers that have a reduced tendency to stick-slip operation. Furthermore, while bearing adapters may be formed of relatively low cost materials, such as cast iron, in some embodiments an insert of a different material may be used for the rocker. Further, some embodiments may employ a member that may tend to center the rocker on installation, and that may tend to perform an auxiliary centering function to tend to urge the rocker to operate from an at rest minimum energy position. 
       FIGS. 2   a - 2   g  show an embodiment of bearing adapter and pedestal seat assembly. Bearing adapter  44  has a lower portion  112  that is formed to accommodate, and to seat upon, bearing  46 , that is itself mounted on the end of a shaft, namely an end of axle  48 . Bearing adapter  44  has an upper portion  114  that has a centrally located, upwardly protruding fitting in the nature of a male bearing adapter interface portion  116 . A mating fitting, in the nature of a female rocker seat interface portion  118  may be rigidly mounted within the roof  120  of the sideframe pedestal. To that end, laterally extending lugs  122  are mounted centrally with respect to pedestal roof  120 . The upper fitting  40 , whichever type it may be, has a body that may be in the form of a plate  126  having, along its longitudinally extending, lateral margins a set of upwardly extending lugs or ears, or tangs  124  separated by a notch, that bracket, and tightly engage lugs  122 , thereby locating upper fitting  40  in position, with the back of the plate  126  of fitting  40  abutting the flat, load transfer face of roof  120 . Upper fitting  40  may be a pedestal seat fitting with a hollowed out female bearing surface, namely portion  118 . As shown in  FIG. 2   g , when the sideframes are lowered over the wheel sets, the end reliefs, or channels  128  lying between the bearing adapter corner abutments  132  seat between the respective side frame pedestal jaws  130 . With the sideframes in place, bearing adapter  44  is thus captured in position with the male and female portions ( 116  and  118 ) of the adapter interface in mating engagement. 
     Male portion  116  ( FIG. 2   d ) has been formed to have a generally upwardly facing surface  142  that has both a first curvature r 1  to permit rocking in the longitudinal direction, and a second curvature r 2  ( FIG. 2   c ) to permit rocking (i.e., swing motion of the sideframe) in the transverse direction. Similarly, in the general case, female portion  118  has a surface having a first radius of curvature R 1  in the longitudinal direction, and a second radius of curvature R 2  in the transverse direction. The engagement of r 1  with R 1  may tend to permit a rocking motion in the longitudinal direction, with resistance to rocking displacement being proportional to the weight on the wheel. That is to say, the resistance to angular deflection is proportional to weight rather than being a fixed spring constant. This may tend to yield passive self-steering in both the light car and fully laden conditions. This relationship is shown in  FIGS. 2   d  and  2   e .  FIG. 2   d  shows the centered, or at rest, non-deflected position of the longitudinal rocking elements.  FIG. 2   e  shows the rocking elements at their condition of maximum longitudinal deflection.  FIG. 2   d  represents a local, minimum potential energy condition for the system.  FIG. 2   e  represents a system in which the potential energy has been increased by virtue of the work done by force F acting longitudinally in the horizontal plane through the center of the axle and bearing, C B , which will tend to yield an incremental increase in the height of the pedestal. Put differently, as the axle is urged to deflect by the force, the rocking motion may tend to raise the car, and thereby to increase its potential energy. 
     The limit of travel in the longitudinal direction is reached when the end face  134  of bearing adapter  44  extending between corner abutments  132 , contacts one or another of travel limiting abutment faces  136  of the thrust blocks of jaws  130 . In general, the deflection may be measured either by the angular displacement of the axle centerline, θ 1 , or by the angular displacement of the rocker contact point on radius r 1 , shown as θ 2 . End face  134  of bearing adapter  44  is planar, and is relieved, or inclined, at an angle η from the vertical. As shown in  FIG. 2   g , abutment face  136  may have a round, cylindrical arc, with the major axis of the cylinder extending vertically. A typical maximum radius R 3  for this surface is 34 inches. When bearing adapter  44  is fully deflected through angle η, end face  134  is intended to meet abutment face  136  in line contact. When this occurs, further longitudinal rocking motion of the male surface (of portion  116 ) against the female surface (of portion  118 ) is inhibited. Thus jaws  130  constrain the arcuate deflection of bearing adapter  44  to a limited range. A typical range for η might be about 3 degrees of arc. A typical maximum value of δ long  may be about +/− 3/16″ to either side of the vertical, at rest, center line. 
     Similarly, as shown in  FIGS. 2   b  and  2   c , in the transverse direction, the engagement of r 2  with R 2  may tend to permit lateral rocking motion, as may be in the manner of a swing motion truck.  FIG. 2   b  shows a centered, at rest, minimum potential energy position of the lateral rocking system.  FIG. 2   c  shows the same system in a laterally deflected condition. In this instance δ 2  is roughly (L pendulum −r 2 ) Sin φ, where, for small angles Sin φ is approximately equal to φ. L pendulum  may be taken as the at rest difference in height between the center of the bottom spring seat,  52 , and the contact interface between the male and female portions  116  and  118 . 
     When a lateral force is applied at the centerplate of the truck bolster, a reaction force is, ultimately, provided at the meeting of the wheels with the rail. The lateral force is transmitted from the bolster into the main spring groups, and then into a lateral force in the spring seats to deflect the bottom of the pendulum. The reaction is carried to the bearing adapter, and hence into the top of the pendulum. The pendulum will then deflect until the weight on the pendulum, multiplied by the moment arm of the deflected pendulum is sufficient to balance the moment of the lateral moment couple acting on the pendulum. 
     This bearing adapter to pedestal seat interface assembly is biased by gravity acting on the pendulum toward a central, or “at rest” position, where there is a local minimum of the potential energy in the system. The fully deflected position shown in  FIG. 2   c  may correspond to a deflection from vertical of the order of less than 10 degrees (and preferably less than 5 degrees) to either side of center, the actual maximum being determined by the spacing of gibbs  106  and  108  relative to plate  104 . Although in general R 1  and R 2  may differ, so the female surface is an outside section of a torus, for R 1  and R 2  may be the same, i.e., so that the bearing surface of the female fitting is formed as a portion of a spherical surface, having neither a major nor a minor axis, but merely being formed on a spherical radius. R 1  and R 2  give a self-centering tendency. That tendency may be quite gentle. Further, and again in the general condition, the smallest of R 1  and R 2  may be equal to or larger than the largest of r 1  and r 2 . If so, then the contact point may have little, if any, ability to transmit torsion acting about an axis normal to the rocking surfaces at the point of contact, so the lateral and longitudinal rocking motions may tend to be torsionally de-coupled, and hence it may be said that relative to this degree of freedom (rotation about the vertical, or substantially vertical axis normal to the rocking contact interface surfaces) the interface is torsionally compliant (that is, the resistance to torsional deflection about the axis through the surfaces at the point of contact may tend to be much smaller than, for example, resistance to lateral angular deflection). For small angular deflections, the torsional stiffness about the normal axis at the contact point, this condition may sometimes be satisfied even where the smaller of the female radii is less than the largest male radius. Although it is possible for r 1  and r 2  to be the same, such that the crowned surface of the bearing adapter (or the pedestal seat, if the relationship is inverted) is a portion of a spherical surface, in the general case r 1  and r 2  may be different, with r 1  perhaps tending to be larger, possibly significantly larger, than r 2 . In general, whether or not r 1  and r 2  are equal, R 1  and R 2  may be the same or different. Where r 1  and r 2  are different, the male fitting engagement surface may be a section of the surface of a torus. It may also be noted that, provided the system may tend to return to a local minimum energy state (i.e., that is self-restorative in normal operation) in the limit either or both of R 1  and R 2  may be infinitely large such that either a cylindrical section is formed or, when both are infinitely large, a planar surface may be formed. In the further alternative, it may be that r 1 =r 2 , and R 1 =R 2 . In one embodiment r 1  may be the same as r 2 , and may be about 40 inches (+/−5″) and R 1  may the same as R 2 , and both may be infinite such that the female surface is planar. 
     Other embodiments of rocker geometry may be considered. In one embodiment R 1 =R 2 =15 inches, r 1 =8⅝ inches and r 2 =5″. In another embodiment, R 1 =R 2 =15 inches, and r 1 =10″ and r 2 =8⅝″ (+/−). In another embodiment r 1 =8⅝, r 2 =5″, R 1 =R 2 =12″ in still another embodiment r 1 =12½″, r 2 =8⅝″ and R 1 =R 2 =15″. 
     The radius of curvature of the male longitudinal rocker, r 1 , may be less than 60 inches, and may lie in the range of 5 to 50 inches, may lie in the range of 8 to 40 inches, and may be about 15 inches. R 1  may be infinite, or may be less than 100 inches, and may be in the range of 10 to 60 inches, or in the narrower range of 12 to 40 inches, and may be in the range of 1 1/10 to 4 times the size of r 1 . 
     The radius of curvature of the male lateral rocker, r 2 , may be between 30 and 50 inches. Alternatively in another type of truck, r 2 , may be less than about 25 or 30 in., and may lie in the range of about 5 to 20 inches. r 2  may lie in the range of about 8 to 16 inches, and may be about 10 inches. Where line contact rocking motion is used, r 2  may perhaps be somewhat smaller than otherwise, perhaps in the range of 3 to 10 inches, and perhaps being about 5 inches. 
     R 2  may be less than 60 inches, and may be less than about 25 or 30 inches, then being less than half the 60 inch crown radius noted above. Alternatively, R 2  may lie in the range of 6 to 40 inches, and may lie in the range of 5 to 15 inches in the case of rolling line contact. R 2  may be between 1½ to 4 times as large as r 2 . In one embodiment R 2  may be roughly twice as large as r 2 , (+/−20%). Where line contact is employed, R 2  may be in the range of 5 to 20 inches, or more narrowly, 8 to 14 inches. 
     Where a spherical male rocker is used on a spherical female cap, in some embodiments the male radius may be in the range of 8-13 in., and may be about 9 in.; the female radius may be in the range of 11-16 in., and may be about 12 in. Where a torus, or elliptical surface is employed, in one embodiment the lateral male radius may be about 7 in., the longitudinal male radius may be about 10 inches, the lateral female radius may be about 12 in. and the longitudinal female radius may be about 15 in. Where a flat female rocker surface is used, and a male spherical surface is used, the male radius of curvature may be in the range of about 20 to about 50 in., and may lie in the narrower range of 30 to 40 in. 
     Many combinations are possible, depending on loading, intended use, and rocker materials. In each case the mating male and female rocker surfaces may tend to be chosen to yield a physically reasonable pairing in terms of expected loading, anticipated load history, and operational life. These may vary. 
     The rocker surfaces herein may tend to be formed of a relatively hard material, which may be a metal or metal alloy material, such as a steel or a material of comparable hardness and toughness. Such materials may have elastic deformation at the location of rocking contact in a manner analogous to that of journal or ball bearings. Nonetheless, the rockers may be taken as approximating the ideal rolling point or line contact (as may be) of infinitely stiff members. This is to be distinguished from materials in which deflection of an elastomeric element be it a pad, or block, of whatever shape, may be intended to determine a characteristic of the dynamic or static response of the element. 
     In one embodiment the lateral rocking constant for a light car may be in the range of about 48,000 to 130,000 in-lbs per radian of angular deflection of the side frame pendulum, or, 260,000 to 700,000 in-lbs per radian for a fully laded car, or more generically, about 0.95 to 2.6 in-lbs per radian per pound of weight borne by the pendulum. Alternatively, for a light (i.e., empty) car the stiffness of the pendulum may be in the range 3,200 to 15,000 lbs per inch, and 22,000 to 61,000 lbs per inch for a fully laden 110 ton truck, or, more generically, in the range of 0.06 to 0.160 lbs per inch of lateral deflection per pound weight borne by the pendulum, as measured at the bottom spring seat. 
     The male and female surfaces may be inverted, such that the female engagement surface is formed on the bearing adapter, and the male engagement surface is formed on the pedestal seat. It is a matter of terminology which part is actually the “seat”, and which is the “rocker”. Sometimes the seat may be assumed to be the part that has the larger radius, and which is usually thought of as being the stationary reference, while the rocker is taken to be the part with the smaller radius, that “rocks” on the stationary seat. However, this is not always so. At root, the relationship is of mating parts, whether male or female, and there is relative motion between the parts, or fittings, whether the fittings are called a “seat” or a “rocker”. The fittings mate at a force transfer interface. The force transfer interface moves as the parts that co-operate to define the rocking interface rock on each other, whichever part may be, nominally, the male part or the female part. One of the mating parts or surfaces is part of the bearing adapter, and another is part of the pedestal. There may be only two mating surfaces, or there may be more than two mating surfaces in the overall assembly defining the dynamic interface between the bearing adapter and the pedestal fitting, or pedestal seat, however it may be called. 
     Both female radii R 1  and R 2  may not be on the same fitting, and both male radii r 1  and r 2  may not be on the same fitting. That is, they may be combined to form saddle shaped fittings in which the bearing adapter has an upper surface that has a male fitting in the nature of a longitudinally extending crown with a laterally extending axis of rotation, having the radius of curvature is r 1 , and a female fitting in the nature of a longitudinally extending trough having a lateral radius of curvature R 2 . Similarly, the pedestal seat fitting may have a downwardly facing surface that has a transversely extending trough having a longitudinally oriented radius of curvature R 1 , for engagement with r 1  of the crown of the bearing adapter, and a longitudinally running, downwardly protruding crown having a transverse radius of curvature r 2  for engagement with R 2  of the trough of the bearing adapter. 
     In a sense, a saddle shaped surface is both a seat and a rocker, being a seat in one direction, and a rocker in the other. As noted above, the essence is that there are two small radii, and two large (or possibly even infinite) radii, and the surfaces form a mating pair that engage in rolling contact in both the lateral and longitudinal directions, with a central local minimum potential energy position to which the assembly is biased to return. It may also be noted that the saddle surfaces can be inverted such that the bearing adapter has r 2  and R 1 , and the pedestal seat fitting has r 1  and R 2 . In either case, the smallest of R 1  and R 2  may be larger than, or equal to, the largest of r 1  and r 2 , and the mating saddle surfaces may tend to be torsionally uncoupled as noted above. 
     
       FIG. 3 
       a  
     
       FIG. 3   a  shows an alternate embodiment of wheelset to sideframe interface assembly, indicated most generally as  150 . The pedestal region of sideframe  151 , as shown in  FIG. 3   a , is substantially similar to those shown in the previous examples, and may be taken as being the same except insofar as may be noted. Similarly, bearing  152  may be taken as representing the location of the end of a wheelset more generally, with the wheelset to sideframe interface assembly including those items, members or elements that are mounted between bearing  152  and sideframe  151 . Bearing adapter  154  may be generally similar to bearing adapter  44  in terms of its lower structure for seating on bearing  152 . As with the bodies of the other bearing adapters described herein, the body of bearing adapter  154  may be a casting or a forging, or a machined part, and may be made of a material that may be a relatively low cost material, such as cast iron or steel, and may be made in generally the same manner as bearing adapters have been made heretofore. Bearing adapter  154  may have a bi-directional rocker  153  employing a compound curvature of first and second radii of curvature according to one or another of the possible combinations of male and female radii of curvature discussed herein. Bearing adapter  154  may differ from those described above in that the central body portion  155  of the adapter has been trimmed to be shorter longitudinally, and the inside spacing between the corner abutment portions has been widened somewhat, to accommodate the installation of an auxiliary centering device, or centering member, or centrally biased restoring member in the nature of, for example, elastomeric bumper pads, such as those identified as resilient pads, or members  156 . Members  156  may be considered a form of restorative centering element, and may also be termed “snubbers” or “bumper” pads. A pedestal seat fitting having a mating rocking surface for permitting lateral and longitudinal rocking, is identified as  158 . As with the other pedestal seat fittings shown and described herein, fitting  158  may be made of a hard metal material, which may be a grade of steel. The engagement of the rocking surfaces may, again, tend to have low resistance to torsion about a predominantly vertical axis through the point of contact. 
     
       FIG. 3 
       b  
     
     In  FIG. 3   b , a bearing adapter  160  is substantially similar to bearing adapter  154 , but differs in having a central recess, socket, cavity or accommodation, indicated generally as  161 , for receiving an insert identified as a first, or lower, rocker member  162 . As with bearing adapter  154 , the main, or central portion of the body  159  of bearing adapter  160  may be of shorter longitudinal extent than might otherwise be the case, being truncated, or relieved, to accommodate resilient members  156 . 
     Accommodation  161  may have a plan view form whose periphery may include one or more keying, or indexing, features or fittings, of which cusps  163  may be representative. Cusps  163  may receive mating keying, or indexing, features or fittings of rocker member  162 , of which lobes  164  may be taken as representative examples. Cusps  163  and lobes  164  may fix the angular orientation of the lower, or first, rocker member  162  such that the appropriate radii of curvature may be presented in each of the lateral and longitudinal directions. For example, cusps  163  may be spaced unequally about the periphery of accommodation  161  (with lobes  164  being correspondingly spaced about the periphery of the insert member  162 ) in a specific spacing arrangement to prevent installation in an incorrect orientation, (such as 90 degrees out of phase). For example, one cusp may be spaced 80 degrees of arc about the periphery from one neighboring cusp, and 100 degrees of arc from another neighboring cusp, and so on to form a rectangular pattern. Many variations are possible. 
     While body  159  of bearing adapter  160  may be made of cast iron or steel, the insert, namely first rocker member  162 , may be made of a different material that may have higher hardness. That different material may present a hardened metal rocker surface such as may have been manufactured by a different process. For example, the insert, member  162 , may be made of a metal, such as a tool steel, or of a steel such as may be used in the manufacture of ball bearings. The material may have a Young&#39;s modulus in excess of 2.5×10 7  p.s.i., such as may be about 3.0×10 7  p.s.i. such as might be typical of a steel. The material may have a yield stress in excess of 100 kpsi, and that yield stress may be in excess of 200 kpsi in some embodiments. Furthermore, upper surface  165  of insert member  162 , which includes that portion that is in rocking engagement with the mating pedestal seat  168 , may be machined or otherwise formed to a high degree of smoothness, akin to a ball bearing surface, and may be heat treated, to give a finished bearing part approximating ideal rolling point or line contact rather then an interface relying upon deflection of the body of the element of an elastomeric pad or block. That is, the rocking stiffness may rely on the geometry of the pendulum, namely the radii of the curvature of the rocking surfaces and the length of the pendulum as distinct from elastic deflection of the material, as in an elastomeric rubber or polymer based pad for example and that may demonstrate significant hysteresis. Put differently, the vertical stiffness of the rocker, based on its bulk material properties, may be two or more orders of magnitude greater than its lateral rocking stiffness, which is based on geometry, such that approximation of the vertical stiffness as being infinite by comparison is physically reasonable. Similarly, the lateral stiffness of the rocker in lateral shear, as manifested by bodily deflection of the rocker elements due to the bulk properties of the rocker materials, may be taken as being at least two orders of magnitude (if not many orders of magnitude) greater than the lateral rocking stiffness of the pendulum such that it is physically reasonable to consider the material to approximate infinite stiffness as compared to the rocker geometry. The foregoing commentary may be taken as applying to each of the embodiments described herein in which there is reference to rolling point or line contact. 
     Similarly, pedestal seat  168  may be made of a hardened material, such as a tool steel or a steel from which bearings are made, formed to a high level of smoothness, and heat treated as may be appropriate of appropriate modulus of elasticity and yield stress, which may be in the ranges discussed above, having a surface formed to mate with surface  165  of rocker member  162 . Alternatively, pedestal seat  168  may have an accommodation indicated as  167 , and an insert member, identified as upper or second rocker member  166 , analogous to accommodation  161  and insert member  162 , with keying or indexing such as may tend to cause the parts to seat in the correct orientation. Member  166  may be formed of a hard material in a manner similar to member  162 , and may have a downward facing rocking surface  157 , which may be machined or otherwise formed to a high degree of smoothness, akin to a ball or roller bearing surface, and may be heat treated, to give a finished bearing part surface for mating, rocking engagement with surface  165 . Where rocker member  162  has both male radii, and the female radii of curvature are both infinite such that the female surface is planar, a wear member having a planar surface such as a spring clip may be mounted in a sprung interference fit in the pedestal roof in lieu of pedestal seat  168 . In one embodiment, the spring clip may be a clip on “Dyna-Clip”™ pedestal roof wear plate such as supplied by TransDyne Inc. Such a clip is shown in an isometric view in  FIG. 8   a  as item  354 . 
     
       FIG. 3 
       e  
     
       FIG. 3   e  shows an alternate embodiment of wheelset to sideframe interface assembly, indicated generally as  170 . Assembly  170  may include a bearing adapter  171 , a pair of resilient members  156 , a rocking assembly that may include a boot, resilient ring or retainer,  172 , a first rocker member  173 , and a second rocker member  174 . A pedestal seat may be provided to mount in the roof of the pedestal as described above, or second rocker member  174  may mount directly in the pedestal roof. 
     Bearing adapter  171  is generally similar to bearing adapter  44 , or  154 , in terms of its lower structure for seating on bearing  152 . The body of bearing adapter  171  may be a casting or a forging, or a machined part, and may be made of a material that may be a relatively low cost material, such as cast iron or steel. Bearing adapter  171  may be provided with a central recess, socket, cavity or accommodation, indicated generally as  176 , for receiving rocker member  173  and rocker member  174 , and retainer  172 . The ends of the main portion of the body of bearing adapter  171  may be of relatively short extent to accommodate resilient members  156 . Accommodation  176  may have the form of a circular opening, that may have a radially inwardly extending flange  177 , whose upwardly facing surface  178  defines a circumferential land upon which to seat first rocker member  173 . Flange  177  may also include drain holes  178 , such as may be 4 holes formed on 90 degree centers, for example. Rocker member  173  has a spherical engagement surface. First rocker member  173  may include a thickened central portion, and a thinner radially distant peripheral portion, having a lower radial edge, or margin, or land, for seating upon, and for transferring vertical loads into, flange  177 . In an alternate embodiment, a non-galling, relatively soft annular gasket, or shim, whether made of a suitable brass, bronze, copper, or other material may be employed on flange  177  under the land. First rocker member  173  may be made of a different material from the material from which the body of bearing adapter  156  is made more generally. That is to say, rocker member  173  may be made of a hard, or hardened material, such as a tool steel or a steel such as might be used in a bearing, that may be harder and may be finished to a generally higher level of precision, and to a finer degree of surface roughness than the body of bearing adapter  156  more generally. Such a material may be suitable for rolling contact operation under high contact pressures. 
     Second rocker member  174  may be a disc of circular shape (in plan view) or other suitable shape having an upper surface for seating in pedestal seat  168 , or, in the event a pedestal seat member is not used, then formed directly to mate with the pedestal roof having an integrally formed seat. First rocker member  173  may have an upper, or rocker surface  175 , having a profile such as may give bi-directional lateral and longitudinal rocking motion when used in conjunction with the mating second, or upper rocker member,  174 . Second rocker member  174  may be made of a different material from the material from which the body of bearing adapter  171 , or the pedestal seat, is made more generally. Second rocker member  174  may be made of a hard, or hardened material, such as a tool steel or a steel such as might be used in a bearing, that may be harder and may be finished to a generally higher level of precision, and to a finer degree of surface roughness than the body of sideframe  151  more generally. Such a material may be suitable for rolling contact operation under high contact pressures, particularly as when operated in conjunction with first rocker member  173 . Where an insert of dissimilar material is used, that material may tend to be rather more costly than the cast iron or relatively mild steel from which bearing adapters may otherwise tend to be made. Further still, an insert of this nature may be removed and replaced when worn, either on the basis of a scheduled rotation, or as the need may arise. 
     Resilient member  172  may be made of a composite or polymeric material, such as a polyurethane. Resilient member  172  may also have apertures, or reliefs  179  such as may be placed in a position for co-operation with corresponding drain holes  178 . The wall height of resilient member  172  may be sufficiently tall to engage the periphery of first rocker member  173 . Further, a portion of the radially outwardly facing peripheral edge of the second, upper, rocking member  174 , may also lie within, or may be partially overlapped by, and may possibly slightly stretchingly engage, the upper margin of resilient member  172  in a close, or interference, fit manner, such that a seal may tend to be formed to exclude dirt or moisture. In this way the assembly may tend to form a closed unit. In that regard, such space as may be formed between the first and second rockers  173 ,  174  inside the dirt exclusion member may be packed with a lubricant, such as a lithium or other suitable grease. 
       FIGS. 4   a - 4   e    
     As shown in  FIGS. 4   a - 4   e , resilient members  156  may have the general shape of a channel, having a central, or back, or transverse, or web portion  181 , and a pair of left and right hand, flanking wing portions  182 ,  183 . Wing portions  182  and  183  may tend to have downwardly and outwardly tending extremities that may tend to have an arcuate lower edge such as may seat over the bearing casing. The inside width of wing portions  182  and  183  may be such as to seat snugly about the sides of thrust blocks  180 . A transversely extending lobate portion  185 , running along the upper margin of web portion  181 , may seat in a radiused rebate  184  between the upper margin of thrust blocks  180  and the end of pedestal seat  168 . The inner lateral edge  186  of lobate portion  185  may tend to be chamfered, or relieved, to accommodate, and to seat next to, the end of pedestal seat  168 . 
     It may be desirable for the rocking assembly at the wheelset to sideframe interface to tend to maintain itself in a centered condition. As noted, the torsionally de-coupled bi-directional rocker arrangements disclosed herein may tend to have rocking stiffnesses that are proportional to the weight placed upon the rocker. Where a longitudinal rocking surface is used to permit self-steering, and the truck is experiencing reduced wheel load, (such as may approach wheel lift), or where the car is operating in the light car condition, it may be helpful to employ an auxiliary restorative centering element that may include a biasing element tending to urge the bearing adapter to a longitudinally centered position relative to the pedestal roof, and whose restorative tendency may be independent of the gravitational force experienced at the wheel. That is, when the bearing adapter is under less than full load, or is unloaded, it may be desirable to maintain a bias to a central position. Resilient members  156  described above may operate to urge such centering. 
       FIGS. 3   c  and  3   d  illustrate the spatial relationship of the sandwich formed by (a) the bearing adapter, for example, bearing adapter  154 ; (b) the centering member, such as, for example, resilient members  156 ; and (c) the pedestal jaw thrust blocks,  180 . Ancillary details such as, for example, drain holes or phantom lines to show hidden features have been omitted from  FIGS. 3   c  and  3   d  for clarity. When resilient member  156  is in place, bearing adapter  154  (or  171 , as may be); may tend to be centered relative to jaws  180 . As installed, the snubber (member  156 ) may seat closely about the pedestal jaw thrust lug, and may seat next to the bearing adapter end wall and between the bearing adapter corner abutments in a slight interference fit. The snubber may be sandwiched between, and may establish the spaced relative position of, the thrust lug and the bearing adapter and may provide an initial central positioning of the mating rocker elements as well as providing a restorative bias. Although bearing adapter  154  may still rock relative to the sideframe, such rocking may tend to deform (typically, locally to compress) a portion of member  156 , and, being elastic, member  156  may tend to urge bearing adapter  154  toward a central position, whether there is much weight on the rocking elements or not. Resilient member  156  may have a restorative force-deflection characteristic in the longitudinal direction that is substantially less stiff than the force deflection characteristic of the fully loaded longitudinal rocker (perhaps one to two orders of magnitude less), such that, in a fully loaded car condition, member  156  may tend not significantly to alter the rocking behavior. In one embodiment member  156  may be made of a polyurethane having a Young&#39;s modulus of some 6,500 p.s.i. In another embodiment the Young&#39;s modulus may be about 13,000 p.s.i. The Young&#39;s modulus of the elastomeric material may be in the range of 4 to 20 k.p.s.i. The placement of resilient members  156  may tend to center the rocking elements during installation. In one embodiment, the force to deflect one of the snubbers may be less than 20% of the force to deflect the rocker a corresponding amount under the light car (i.e., unloaded) condition, and may, for small deflections, have an equivalent force/deflection curve slope that may be less than 10% of the force deflection characteristic of the longitudinal rocker. 
     
       FIG. 5 
     
     Thus far only primary wedge angles have been discussed.  FIG. 5  shows an isometric view of an end portion of a truck bolster  210 . As with all of the truck bolsters shown and discussed herein, bolster  210  is symmetrical about the central longitudinal vertical plane of the bolster (i.e., cross-wise relative to the truck generally) and symmetrical about the vertical mid-span section of the bolster (i.e., the longitudinal plane of symmetry of the truck generally, coinciding with the railcar longitudinal center line). Bolster  210  has a pair of spaced apart bolster pockets  212 ,  214  for receiving damper wedges  216 ,  218 . Pocket  212  is laterally inboard of pocket  214  relative to the side frame of the truck more generally. Wear plate inserts  220 ,  222  are mounted in pockets  212 ,  214  along the angled wedge face. 
     As can be seen, wedges  216 ,  218  have a primary angle, α as measured between vertical and the angled trailing vertex  228  of outboard face  230 . For the embodiments discussed herein, primary angle α may tend to lie in the range of 35-55 degrees, possibly about 40-50 degrees. This same angle α is matched by the facing surface of the bolster pocket, be it  212  or  214 . A secondary angle β gives the inboard, (or outboard), rake of the sloped surface  224 , (or  226 ) of wedge  216  (or  218 ). The true rake angle can be seen by sighting along plane of the sloped face and measuring the angle between the sloped face and the planar outboard face  230 . The rake angle is the complement of the angle so measured. The rake angle may tend to be greater than 5 degrees, may lie in the range of 5 to 20 degrees, and is preferably about 10 to 15 degrees. A modest rake angle may be desirable. 
     When the truck suspension works in response to track perturbations, the damper wedges may tend to work in their pockets. The rake angles yield a component of force tending to bias the outboard face  230  of outboard wedge  218  outboard against the opposing outboard face of bolster pocket  214 . Similarly, the inboard face of wedge  216  may tend to be biased toward the inboard planar face of inboard bolster pocket  212 . These inboard and outboard faces of the bolster pockets may be lined with a low friction surface pad, indicated generally as  232 . The left hand and right hand biases of the wedges may tend to keep them apart to yield the full moment arm distance intended, and, by keeping them against the planar facing walls, may tend to discourage twisting of the dampers in the respective pockets. 
     Bolster  210  includes a middle land  234  between pockets  212 ,  214 , against which another spring  236  may work. Middle land  234  is such as might be found in a spring group that is three (or more) coils wide. However, whether two, three, or more coils wide, and whether employing a central land or no central land, bolster pockets can have both primary and secondary angles as illustrated in the example embodiment of  FIG. 5   a , with or without wear inserts. 
     Where a central land, e.g., land  234 , separates two damper pockets, the opposing side frame column wear plates need not be monolithic. That is, two wear plate regions could be provided, one opposite each of the inboard and outboard dampers, presenting planar surfaces against which the dampers can bear. The normal vectors of those regions may be parallel, the surfaces may be co-planar and perpendicular to the long axis of the side frame, and may present a clear, un-interrupted surface to the friction faces of the dampers. 
     
       FIG. 1 
       e  
     
       FIG. 1   e  shows an example of a three piece railroad car truck, shown generally as  250 . Truck  250  has a truck bolster  252 , and a pair of sideframes  254 . The spring groups of truck  250  are indicated as  256 . Spring groups  256  are spring groups having three springs  258  (inboard corner),  260  (center) and  262  (outboard corner) most closely adjacent to the sideframe columns  254 . A motion calming, kinematic energy dissipating element, in the nature of a friction damper  264 ,  266  is mounted over each of central springs  260 . 
     Friction damper  264 ,  266  has a substantially planar friction face  268  mounted in facing, planar opposition to, and for engagement with, a side frame wear member in the nature of a wear plate  270  mounted to sideframe column  254 . The base of damper  264 ,  266  defines a spring seat, or socket  272  into which the upper end of central spring  260  seats. Damper  264 ,  266  has a third face, being an inclined slope or hypotenuse face  274  for mating engagement with a sloped face  276  inside sloped bolster pocket  278 . Compression of spring  260  under an end of the truck bolster may tend to load damper  264  or  266 , as may be, such that friction face  268  is biased against the opposing bearing face of the sideframe column,  280 . Truck  250  also has wheelsets whose bearings are mounted in the pedestal  284  at either ends of the side frames  254 . Each of these pedestals may accommodate one or another of the sideframe to bearing adapter interface assemblies described above and may thereby have a measure of self steering. 
     In this embodiment, vertical face  268  of friction damper  264 ,  266  may have a bearing surface having a co-efficient of static friction, :s, and a co-efficient of dynamic or kinetic friction, :k, that may tend to exhibit little or no “stick-slip” behavior when operating against the wear surface of wear plate  270 . In one embodiment, the coefficients of friction are within 10% of each other. In another embodiment the coefficients of friction are substantially equal and may be substantially free of stick-slip behavior. In one embodiment, when dry, the coefficients of friction may be in the range of 0.10 to 0.45, may be in the narrower range of 0.15 to 0.35, and may be about 0.30. Friction damper  264 ,  266  may have a friction face coating, or bonded pad  286  having these friction properties, and corresponding to those inserts or pads described in the context of  FIGS. 6   a - 6   c , and  FIGS. 7   a - 7   h . Bonded pad  286  may be a polymeric pad or coating. A low friction, or controlled friction pad or coating  288  may also be employed on the sloped surface of the damper. In one embodiment that coating or pad  288  may have coefficients of static and dynamic friction that are within 20%, or, more narrowly, 10% of each other. In another embodiment, the coefficients of static and dynamic friction are substantially equal. The co-efficient of dynamic friction may be in the range of 0.10 to 0.30, and may be about 0.20. 
       FIGS. 6   a  to  6   c    
     The bodies of the damper wedges themselves may be made from a relatively common material, such as a mild steel or cast iron. The wedges may then be given wear face members in the nature of shoes, wear inserts or other wear members, which may be intended to be consumable items. In  FIG. 6   a , a damper wedge is shown generically as  300 . The replaceable, friction modification consumable wear members are indicated as  302 ,  304 . The wedges and wear members may have mating male and female mechanical interlink features, such as the cross-shaped relief  303  formed in the primary angled and vertical faces of wedge  300  for mating with the corresponding raised cross shaped features  305  of wear members  302 ,  304 . Sliding wear member  302  may be made of a material having specified friction properties, and may be obtained from a supplier of such materials as, for example, brake and clutch linings and the like, such as Railway Friction Products. The materials may include materials that are referred to as being non-metallic, low friction materials, and may include UHMW polymers, and may be formed as removable and replaceable pads or blocks or linings. 
     Although  FIGS. 6   a  and  6   c  show consumable inserts in the nature of wear plates, namely wear members  302 ,  304  the entire bolster pocket may be made as a replaceable part. It may be a high precision casting, or may include a sintered powder metal assembly having suitable physical properties. The part so formed may then be welded into place in the end of the bolster. 
     The underside of the wedges described herein, wedge  300  being typical in this regard, may have a seat, or socket  307 , for engaging the top end of the spring coil, whichever spring it may be, spring  262  being shown as typically representative. Socket  307  serves to discourage the top end of the spring from wandering away from the intended generally central position under the wedge. A bottom seat, or boss, for discouraging lateral wandering of the bottom end of the spring is shown in  FIG. 1   e  as item  308 . It may be noted that wedge  300  has a primary angle, but does not have a secondary rake angle. In that regard, wedge  300  may be used as damper  264 ,  266  of truck  250  of  FIG. 1   e , for example, and may provide friction damping with little or no “stick-slip” behavior, but rather friction damping for which the coefficients of static and dynamic friction are equal, or only differ by a small (less than about 20%, perhaps less than 10%) difference. Wedge  300  may be used in truck  250  in conjunction with a bi-directional bearing adapter of any of the embodiments described herein. Wedge  300  may also be used in a four cornered damper arrangement, as in truck  22 , for example, where wedges may be employed that may lack secondary angles. 
       FIGS. 7   a - 7   h    
     Referring to  FIGS. 7   a - 7   e , a damper  310  is shown such as may be used in truck  22 , or any of the other double damper trucks described herein, such as may have appropriately formed, mating bolster pockets. Damper  310  is similar to damper  300 , but may include both primary and secondary angles. Damper  310  may, arbitrarily, be termed a right handed damper wedge.  FIGS. 7   a - 7   e  are intended to be generic such that it may be understood also to represent the left handed, mirror image of a mating damper with which damper  310  would form a matched pair. 
     Wedge  310  has a body  312  that may be made by casting or by another suitable process. Body  312  may be made of steel or cast iron, and may be substantially hollow. Body  312  has a first, substantially planar platen portion  314  having a first face for placement in a generally vertical orientation in opposition to a sideframe bearing surface, for example, a wear plate mounted on a sideframe column. Platen portion  314  may have a rebate, or relief, or depression formed therein to receive a bearing surface wear member, indicated as member  316 . Member  316  may be a material having specific friction properties when used in conjunction with the sideframe column wear plate material. For example, member  316  may be formed of a brake lining material, and the column wear plate may be formed from a high hardness steel. This material may be formed as a removable and replaceable pad or block. 
     Body  312  may include a base portion  318  that may extend rearwardly from and generally perpendicularly to, platen portion  314 . Base portion  318  may have a relief  320  formed therein in a manner to form, roughly, the negative impression of an end of a spring coil, such as may receive a top end of a coil of a spring of a spring group, such as spring  262 . Base portion  318  may join platen portion  314  at an intermediate height, such that a lower portion  321  of platen portion  314  may depend downwardly therebeyond in the manner of a skirt. That skirt portion may include a corner, or wrap around portion  322  formed to seat around a portion of the spring. 
     Body  312  may also include a diagonal member in the nature of a sloped member  324 . Sloped member  324  may have a first, or lower end extending from the distal end of base  318  and running upwardly and forwardly toward a junction with platen portion  314 . An upper region  326  of platen portion  314  may extend upwardly beyond that point of junction, such that damper wedge  310  may have a footprint having a vertical extent somewhat greater than the vertical extent of sloped member  324 . Sloped member  324  may also have a socket or seat in the nature of a relief or rebate  328  formed therein for receiving a sliding face member  330  for engagement with the bolster pocket wear plate of the bolster pocket into which wedge  310  may seat. As may be seen, sloped member  324  (and face member  330 ) are inclined at a primary angle α, and a secondary angle β. Sliding face member  330  may be an element of chosen, possibly relatively low, friction properties (when engaged with the bolster pocket wear plate), such as may include desired values of coefficients of static and dynamic friction. In one embodiment the coefficients of static and dynamic friction may be substantially equal, may be about 0.2 (+/−20%, or, more narrowly +/−10%), and may be substantially free of stick-slip behavior. 
     In the alternative embodiment of  FIG. 7   g , a damper wedge  332  is similar to damper wedge  310 , but, in addition to pads or inserts for providing modified or controlled friction properties on the friction face for engaging the sideframe column and on the face for engaging the slope of the bolster pocket, damper wedge  332  may have pads or inserts such as pad  334  on the side faces of the wedge for engaging the side faces of the bolster pockets. In this regard, it may be desirable for pad  334  to have low coefficients of friction, and to tend to be free of stick slip behavior. The friction materials may be cast or bonded in place, and may include mechanical interlocking features, such as shown in  FIG. 6   a , or bosses, grooves, splines, or the like such as may be used for the same purpose. Similarly, in the alternative embodiment of  FIG. 7   h , a damper wedge  336  is provided in which the slope face insert or pad, and the side wall insert or pad form a continuous, or monolithic, element, indicated as  338 . The material of the pad or insert may, again, be cast in place, and may include mechanical interlock features. 
       FIGS. 8   a - 8   f    
       FIGS. 8   a - 8   f  show an alternate bearing adapter assembly to that of  FIG. 3   a . The assembly, indicated generally as  350 , may differ from that of  FIG. 3   a  insofar as bearing adapter  344  may have an upper surface  346  that may be a load bearing interface surface of significant extent, that may be substantially planar and horizontal, such that it may act as a base upon which to seat a rocker element,  348 . Rocker element  348  may have an upper, or rocker, surface  352  having a suitable profile, such as a compound curvature having lateral and longitudinal radii of curvature, for mating with a corresponding rocker engagement surface of a pedestal seat liner  354 . As noted above, in the general case each of the two rocking engagement surface may have both lateral and longitudinal radii of curvature, such that there are mating lateral male and female radii, and mating longitudinal male and female radii. In one embodiment, both the female radii may be infinite, such that the pedestal seat may have a planar engagement surface, and the pedestal seat liner may be a wear liner, or similar device. 
     Rocker element  348  may also have a lower surface  356  for seating on, mating with, and for transferring loads into, upper surface  346  over a relatively large surface area, and may have a suitable through thickness for diffusing vertical loading from the zone of rolling contact to the larger area of the land (i.e., surface  346 , or a portion thereof) upon which rocker element  348  sits. Lower surface  356  may also include a keying, or indexing feature  358  of suitable shape, and may include a centering feature  360 , both to aid in installation, and to aid in re-centering rocker element  348  in the event that it should be tempted to migrate away from the central position during operation. Indexing feature  358  may also include an orienting element for discouraging mis-orientation of rocker element  348 . Indexing feature  358  may be a cavity  362  of suitable shape to mate with an opposed button  364  formed on the upper surface  346  of bearing adapter  344 . If this shape is non-circular, it may tend to admit of only one permissible orientation. The orienting element may be defined in the plan form shape of cavity  362  and button  364 . Where the various radii of curvature of rocker element  348  differ in the lateral and longitudinal directions, it may be that two positions 180 degrees out of phase may be acceptable, whereas another orientation may not. While an ellipse of differing major and minor axes may serve this purpose, the shape of cavity  362  and button  364  may be chosen from a large number of possibilities, and may have a cruciform or triangular shape, or may include more than one raised feature in an asymmetrical pattern, for example. The centering feature may be defined in the tapered, or sloped, flanks  368  and  370  of cavity  362  and  364  respectively, in that, once positioned such that flanks  368  and  370  begin to work against each other, a normal force acting downward on the interface may tend to cause the parts to center themselves. 
     Rocker element  348  has an external periphery  372 , defining a footprint. Resilient members  374  may be taken as being the same as resilient members  156 , noted above, except insofar as resilient members  374  may have a depending end portion for nesting about the thrust block of a jaw of the pedestal, and also a predominantly horizontally extending portion  376  for overlying a substantial portion of the generally flat or horizontal upper region of bearing adapter  344 . That is, the outlying regions of surface  346  of bearing adapter  344  may tend to be generally flat, and may tend, due to the general thickness of rocker element  348 , to be compelled to stand in a spaced apart relationship from the opposed, downwardly facing surface of the pedestal seat, such as may be, for example, the exposed surface of a wear liner such as item  354 , or a seat such as item  168 , or such other mating part as may be suitable. Portion  376  is of a thickness suitable for lying in the gaps so defined, and may tend to be thinner than the mean gap height so as not to interfere with operation of the rocker elements. Horizontally extending portion  376  may have the form of a skirt such as may include a pair of left and right hand arms or wings  378  and  380  having a profile, when seen in plan view, for embracing a portion of periphery  372 . Resilient member  374  has a relief  382  defined in the inwardly facing edge. Where rocker member  348  has outwardly extending blisters, or cusps, akin to item  164 , relief  382  may function as an indexing or orientation feature. A relatively coarse engagement of rocker element  348  may tend to result in wings  378  and  380  urging rocker element  348  to a generally centered position relative to bearing adapter  344 . This coarse centering may tend to cause cavity  362  to pick up on button  364 , such that rocker member  348  is then urged to the desired centered position by a fine centering feature, namely the chamfered flanks  368 ,  370 . The root of portion  376  may be relieved by a radius  384  adjacent the juncture of surface  346  with the end wall  386  of bearing adapter  348  to discourage chaffing of resilient member  372 ,  374  at that location. 
     Without the addition of a multiplicity of drawings, it may be noted that rocker element  348  could, alternatively, be inverted so as to seat in an accommodation formed in the pedestal roof, with a land facing toward the roof, and a rocking surface facing toward a mating bearing adapter, be it adapter  44  or some other. 
       FIGS. 9   a  and  9   b    
       FIG. 9   a  shows an alternative arrangement to that of  FIG. 3   a  or  FIG. 8   a . In the wheelset to sideframe interface assembly of  FIG. 9   a , indicated generally as  400 , bearing adapter  404  may be substantially similar to bearing adapter  344 , and may have an upper surface  406  and a rocker element  408  that interact in the same manner as rocker element  348  interacts with surface  346 . (Or, in the inverted case, the rocker element may be seated in the pedestal roof, and the bearing adapter may have a mating upwardly facing rocker surface). The rocker element may interact with a pedestal seat fitting  410  such as may be a wear liner seated in the pedestal roof. Rocker element  408  and the body of bearing adapter  404  may have mating indexing features as described in the context of  FIGS. 8   a  to  8   e.    
     Rather than two resilient members, such as items  374 , however, assembly  400  employs a single resilient member  412 , such as may be a monolithic cast material, be it polyurethane or a suitable rubber or rubberlike material such as may be used, for example, in making an LC pad or a Pennsy pad. An LC pad is an elastomeric bearing adapter pad available from Lord Corporation of Erie Pa. An example of an LC pad may be identified as Standard Car Truck Part Number SCT 5578. In this instance, resilient member  412  has first and second end portions  414 ,  416  for interposition between the thrust lugs of the jaws of the pedestal and the ends  418  and  420  of the bearing adapter. End portions  414 ,  416  may tend to be a bit undersize so that, once the roof liner is in place, they may slide vertically into place on the thrust lugs, possibly in a modest interference fit. The bearing adapter may slide into place thereafter, and again, may do so in a slight interference fit, carrying the rocker element  408  with it into place. 
     Resilient member  412  may also have a central or medial portion  422  extending between end portions  414 ,  416 . Medial portion  422  may extend generally horizontally inward to overlie substantial portions of the upper surface bearing adapter  404 . Resilient member  412  may have an accommodation  424  formed therein, be it in the nature of an aperture, or through hole, having a periphery of suitable extent to admit rocker element  408 , and so to permit rocker element  408  to extend at least partially through member  412  to engage the mating rocking element of the pedestal seat. It may be that the periphery of accommodation  422  is matched to the shape of the footprint of rocker element  408  in the manner described in the context of  FIGS. 8   a  to  8   e  to facilitate installation and to facilitate location of rocker element  408  on bearing adapter  404 . In one embodiment resilient member  412  may be formed in the manner of a Pennsy Pad with a suitable central aperture formed therein. 
       FIG. 9   b  shows a Pennsy pad installation. In this installation, a bearing adapter is indicated as  430 , and an elastomeric member, such as may be a Pennsy pad, is indicated as  432 . On installation, member  432  seats between the pedestal roof and the bearing adapter. The term “Pennsy pad”, or “Pennsy Adapter Plus”, refers to a kind of elastomeric pad developed by Pennsy Corporation of Westchester Pa. One example of such a pad is illustrated in U.S. Pat. No. 5,562,045 of Rudibaugh et al., issued Oct. 6, 1996 (and which is incorporated herein by reference).  FIG. 9   b  may include a pad  432  and bearing adapter of  430  the same, or similar, nature to those shown and described in the U.S. Pat. No. 5,562,045. The Pennsy pad may tend to permit a measure of passive steering. The Pennsy pad installation of  FIG. 9   b  can be installed in the sideframe of  FIG. 1   a , in combination with a four cornered damper arrangement, as indicated in  FIGS. 1   a - 1   d . In this embodiment the truck may be a Barber S2HD truck, modified to carry a damper arrangement, such as a four-cornered damper arrangement, such as may have an enhanced restorative tendency in the face of non-square deformation of the truck, having dampers that may include friction surfaces as described herein. 
       FIGS. 10   a - 10   e    
       FIG. 10   a  shows a further alternate embodiment of wheelset to sideframe interface assembly to that of  FIG. 3   a  or  FIG. 8   a . In this instance, bearing adapter  444  may have an upper rocker surface of any of the configurations discussed above, or may have a rocker element in the manner of bearing adapter  344 . 
     The underside of bearing adapter  444  may have not only a circumferentially extending medial groove, channel or rebate  446 , having an apex lying on the transverse plane of symmetry of bearing adapter  444 , but also a laterally extending underside rebate  448  such as may tend to lie parallel to the underlying longitudinal axis of the wheelset shaft and bearing centerline (i.e., the axial direction) such that the underside of bearing adapter  444  has four corner lands or pads  450  arranged in an array for seating on the casing of the bearing. In this instance, each of the pads, or lands, may be formed on a curved surface having a radius conforming to a body of revolution such as the outer shell of the bearing. Rebate  448  may tend to lie along the apex of the arch of the underside of bearing adapter  444 , with the intersection of rebates  446  and  448 . Rebate  448  may be relatively shallow, and may be gently radiused into the surrounding bearing adapter body. The body of bearing adapter  444  is more or less symmetrical about both its longitudinal central vertical plane (i.e., on installation, that plane lying vertical and parallel to, if not coincident with, the longitudinal vertical central plane of the sideframe), and also about its transverse central plane (i.e., on installation, that plane extending vertically radially from the center line of the axis of rotation of the bearing and of the wheelset shaft). It may be noted that axial rebate  448  may tend to lie at the section of minimum cross-sectional area of bearing adapter  444 . Rebates  446  and  448  may tend to divide, and spread, the vertical load carried through the rocker element over a larger area of the casing of the bearing, and hence more evenly to distribute the load into the rollers of the bearing than might otherwise be the case. It is thought that this may tend to encourage longer bearing life. 
     In the general case, bearing adapter  444  may have an upper surface having a crown to permit self-steering, or may be formed to accommodate a self-steering apparatus such as an elastomeric pad, such as a Pennsy Pad or other pad. In the event that a rocker surface is employed, whether by way of a separable insert, or a disc, or is integrally formed in the body of the bearing adapter, the location of the contact of the rocker in the resting position may tend to lie directly above the center of the bearing adapter, and hence above the intersection of the axial and circumferential rebates in the underside of bearing adapter  444 . 
       FIGS. 11   a - 11   f    
       FIGS. 11   a - 11   f  show views of a bearing adapter  452 , a pedestal seat insert  454  and elastomeric bumper pad members  456 , as an assembly for insertion between bearing  46  and sideframe  26 . Bearing adapter  452  and pad members  456  are generally similar to bearing adapter  171  and members  156 , respectively. They differ, however, insofar as bearing adapter  452  has thrust block standoff elements  460 ,  462  located at either end thereof, and the lower corners of bumpers  456  have been truncated accordingly. It may be that for a certain range of deflection, an elastomeric response is desired, and may be sufficient to accommodate a high percentage of in-service performance. However, excursion beyond that range of deflection might tend to cause damage, or reduction in life, to pad members  456 . Standoff elements  460 ,  462  may act as limiting stops to bound that range of motion. Standoff elements  460 ,  462  may have the form of shelves, or abutments, or stops  466 ,  468  mounted to, and standing proud of, the laterally inwardly facing faces of the corner abutment portions  470 ,  472  of bearing adapter  452  more generally. As installed, stops  466 ,  468  underlie toes  474 ,  476  of members  456 . As may be noted, toes  474 ,  476  have a truncated appearance as compared to the toes of member  356  in order to stand clear of stops  466 ,  468  on installation. In the at rest, centered condition, stops  466 ,  468  may tend to stand clear of the pedestal jaw thrust blocks by some gap distance. When the lateral deflection of the elastomer in member  456  reaches the gap distance, the thrust lug may tend to bottom against stop  466  or  468 , as the case may be. The sheltering width of stops  466 ,  468  (i.e., the distance by which they stand proud of the inner face of corner abutment portions  470 ,  472 ) may tend to provide a reserve compression zone for wings  475 ,  477  and may thereby tend to prevent them from being unduly squeezed or pinched. Pedestal seat insert  454  may be generally similar to liner  354 , but may include radiused bulges  480 ,  482 , and a thicker central portion  484 . Bearing adapter  452  may include a central bi-directional rocker portion  486  for mating rocking engagement with the downwardly facing rocking surface of central portion  484 . The mating surfaces may conform to any of the combinations of bi-directional rocking radii discussed herein. Rocker portion  486  may be trimmed laterally as at longitudinally running side shoulders  488 ,  490  to accommodate bulges  480 ,  482 . 
     Bearing adapter  452  may also have different underside grooving,  492  in the nature of a pair of laterally extending tapered lobate depressions, cavities, or reliefs  494 ,  496  separated by a central bridge region  498  having a deeper section and flanks that taper into reliefs  494 ,  496 . Reliefs  494 ,  496  may have a major axis that runs laterally with respect to the bearing adapter itself, but, as installed, runs axially with respect to the axis of rotation of the underlying bearing. The absence of material at reliefs  494 ,  496  may tend to leave a generally H-shaped footprint on the circumferential surface  500  that seats upon the outside of bearing  46 , in which the two side regions, or legs, of the H form lands or pads  502 ,  504  joined by a relatively narrow waist, namely bridge region  498 . To the extent that the undersurface of the lower portion of bearing adapter  452  conforms to an arcuate profile, such as may accommodate the bearing casing, reliefs  494 ,  496  may tend to run, or extend, predominantly along the apex of the profile, between the pads, or lands, that lie to either side. This configuration may tend to spread the rocker rolling contact point load into pads  502 ,  504  and thence into bearing  46 . Bearing life may be a function of peak load in the rollers. By leaving a space between the underside of the bearing adapter and the top center of the bearing casing over the bearing races, reliefs  494 ,  496  may tend to prevent the vertical load being passed in a concentrated manner predominantly into the top rollers in the bearing. Instead, it may be advantageous to spread the load between several rollers in each race. This may tend to be encouraged by employing spaced apart pads or lands, such as pads  502 ,  504 , that seat upon the bearing casing. Central bridge region  498  may seat above a section of the bearing casing under which there is no race, rather than directly over one of the races. Bridge region  498  may act as a central circumferential ligature, or tension member, intermediate bearing adapter end arches  506 ,  508  such as may tend to discourage splaying or separation of pads  502 ,  504  away from each other as vertical load is applied. 
       FIGS. 12   a - 12   d    
       FIGS. 12   a  to  12   d  show an alternate assembly to that of  FIG. 11   a , indicated generally as  510  for seating in a sideframe  512 . Bearing  46  and bearing adapter  452  may be as before. Assembly  510  may include an upper rocker fitting identified as pedestal seat member  514 , and resilient members  516 . Sideframe  512  may be such that the upper rocker fitting, namely pedestal seat member  514  may have a greater through thickness, t, than otherwise. This thickness, t s  may be greater than 10% of the magnitude of the width Ws of the pedestal seat member, and may be about 20 (+/−5) % of the width. In one embodiment the thickness may be roughly the same as the thickness of and ‘LC pad’ such as may be obtained from Lord Corporation. Such thickness may be greater than 7/16″, and such thickness may be 1 inch (+/−⅛″). Pedestal seat member  514  may tend to have a greater thickness for enhancing the spreading of the rocker contact load into sideframe  512 . It may also be used as part of a retro-fit installation in sideframes such as may formerly have been made to accommodate LC pads. 
     Pedestal seat member  514  may have a generally planar body  518  having upturned lateral margins  520  for bracketing, and seating about, the lower edges of the sideframe pedestal roof member  522 . The major portion of the upper surface of body  518  may tend to mate in planar contact with the downwardly facing surface of roof member  522 . Seat member  514  may have protruding end potions  524  that extend longitudinally from the main, planar portion of body  518 . End portions  524  may include a deeper nose section  526 , that may stand downwardly proud of two wings  528 ,  530 . The depth of nose section  526  may correspond to the general through thickness depth of member  514 . The lower, downwardly facing surface  532  of member  518  (as installed) may be formed to mate with the upper surface of the bearing adapter, such that a bi-directional rocking interface is achieved, with a combination of male and female rocking radii as described herein. In one embodiment the female rocking surface may be planar. 
     Resilient members  516  may be formed to engage protruding portions  524 . That is, resilient member  516  may have the generally channel shaped for of resilient member  156 , having a lateral web  534  standing between a pair of wings  536 ,  538 . However, in this embodiment, web  534  may extend, when installed, to a level below the level of stops  466 ,  468 , and the respective base faces  540 ,  542  of wings  536 ,  538  are positioned to sit above stops  466 ,  468 . A superior lateral wall, or bulge,  544  surmounts the upper margin of web  534 , and extends longitudinally, such as may permit it to overhang the top of the sideframe jaw thrust lug  546 . The upper surface of bulge  544  may be trimmed, or flattened to accommodate nose section  526 . The upper extremities of wings  536 ,  538  terminate in knobs, or prongs, or horns  548 ,  550  that stand upwardly proud of the flattened surface  552  of bulge  544 . As installed, the upper ends of horns  548 ,  550  underlie the downwardly facing surfaces of wings  536 ,  538 . 
     In the event that an installer might attempt to install bearing adapter  452  in sideframe  512  without first placing pedestal seat member  512  in position, the height of horns  548 ,  550  is sufficient to prevent the rocker surface of bearing adapter  452  from engaging sideframe roof member  522 . That is, the height of the highest portion of the crown of the rocker surface  552  of the bearing adapter is less than the height of the ends of horns  548 ,  550  when horns  548 ,  550  are in contact with stops  466 ,  468 . However, when pedestal seat member  512  is correctly in place, nose section  526  is located between wings  536 ,  538 , and wings  536 ,  538  are captured above horns  548 ,  550 . In this way, resilient members  514 , and in particular horns  548 ,  550 , act as installation error detection elements, or damage prevention elements. 
     The steps of installation may include the step of removing an existing bearing adapter, removing an existing elastomeric pad, such as an LC pad, installing pedestal seat fitting  514  in engagement with roof  522 ; seating of resilient members  514  above each of thrust lugs  546 ; and sliding bearing adapter  452  between resilient pad members  514 . Resilient pad members  514  then serve to locate other elements on assembly, to retain those elements in service, and to provide a centering bias to the mating rocker elements, as discussed above. 
       FIGS. 13   a - 13   g    
       FIGS. 13   a  to  13   g  show and alternate bearing adapter  144  and pedestal seat  146  pair. Bearing adapter  144  is substantially the same as bearing adapter  44 , except insofar as bearing adapter  44  has a fully curved top surface  142 , whereas bearing adapter  144  has an upper surface that has a flat central portion  148  between somewhat elevated side portions  149 . The male bearing surface portion  147  is located centrally on flat central portion  148 , and extends upwardly therefrom. As with bearing adapter  44 , bearing adapter  144  has first and second radii r 1  and r 2 , formed in the longitudinal and transverse directions respectively, such that the upwardly protruding surface so formed is a toroidal surface. Pedestal seat  146  is substantially similar to pedestal seat fitting  38 . Pedestal seat  146  has a body having an upper surface  145  that seats in planar abutment against the downwardly facing surface of pedestal roof  120 , and upwardly extending tangs  124  that engage lugs  122  as before. 
     While in the general sense, the female engagement fitting portion, namely the hollow depression formed in the lower face of seat  146 , is formed on longitudinal and lateral radii R 1  and R 2 , as above, when these two radii are equal a spherical surface  143  is formed, giving the circular plan view of  FIG. 13   a .  FIGS. 13   f  and  13   g  serve to illustrate that the male and female surfaces may be inverted, such that the female engagement surface  560  is formed on bearing adapter  562 , and the male engagement surface  564  on seat  566 . 
       FIGS. 14   a - 14   e    
       FIGS. 14   a - 14   e  show enlarged views of bearing adapter  44  and pedestal seat fitting  38 . The compound curve of upwardly facing surface  142  runs fully to terminate at the end faces  134 , and the side faces  570  of bearing adapter  44 . The side faces show the circularly downwardly arched lower walls margins  572  of side faces  570  that seat about bearings  46 . In all other respects, for the purposes of this description, bearing adapter  44  can be taken as being the same as bearing adapter  144 . 
       FIGS. 15   a - 15   c    
       FIGS. 15   a - 15   c , show a conceptually similar bearing adapter and pedestal seat combination to that of  FIGS. 13   a  to  13   g , but rather than having the interface portions standing proud of the remainder of the bearing adapter, the male portion  574  is sunken into the top of the bearing adapter, and the surrounding surface  576  is raised up. The mating female portion  578  while retaining its hollowed out shape, stands proud of the surrounding structure of the seat to provide a corresponding mating surface. The longitudinally extending phantom lines indicate drain ports to discourage the collection of water. 
       FIGS. 16   a - 16   e    
     Both female radii R 1  and R 2  need not be on the same fitting, and both male radii r 1  and r 2  need not be on the same fitting. In the saddle shaped fittings of  FIGS. 16   a  to  16   e , a bearing adapter  580  is of substantially the same construction as bearing adapters  44  and  144 , except insofar as bearing adapter  580  has an upper surface  592  that has a male fitting in the nature of a longitudinally extending crown  582  with a laterally extending axis of rotation, for which the radius of curvature is r 1 , and a female fitting in the nature of a longitudinally extending trough  584  having a lateral radius of curvature R 2 . Similarly, pedestal fitting  586  mounted in roof  120  has a generally downwardly facing surface  594  that has a transversely extending trough  588  having a longitudinally oriented radius of curvature R 1 , for engagement with r 1  of crown  582 , and a longitudinally running, downwardly protruding crown  590  having a transverse radius of curvature r 2  for engagement with R 2  of trough  584 . In  FIGS. 16   f  and  16   g  the saddle surfaces are inverted such that whereas bearing adapter  580  has r 1  and R 2 , bearing adapter  596  has r 2  and R 1 . Similarly, whereas pedestal fitting  586  has r 2  and R 1 , pedestal fitting  598  has r 1  and R 2 . In either case, the smallest of R 1  and R 2  may be larger than, or equal to, the largest of r 1  and r 2 , and the mating opposed saddle surfaces, over the desired range of motion, may tend to be torsionally decoupled as in bearing adapters  44  and  144 . 
       FIGS. 17   a - 17   d    
     It may be desired that the vertical forces transmitted from the pedestal roof into the bearing adapter be passed through line contact, rather than the bi-directional rolling or rocking point contact. A pedestal seat to bearing adapter interface assembly having line contact rocker interfaces is represented by  FIGS. 17   a  to  17   d . A bearing adapter  600  has a hollowed out transverse cylindrical upper surface  602 , acting as a female engagement fitting portion formed on radius R 1 . Surface  602  may be a round cylindrical section, or it may be a parabolic, or other cylindrical section. 
     The corresponding pedestal seat fitting  604  may have a longitudinally extending female fitting, or trough,  606  having a cylindrical surface  608  formed on radius r 1 . Again, fitting  604  is cylindrical, and may be a round cylindrical section although, alternatively, it could be parabolic, elliptic, or some other shape for producing a rocking motion. Trapped between bearing adapter  600  and pedestal seat fitting  604  is a rocker member  610 . Rocker member  610  has a first, or lower portion  612  having a protruding male cylindrical rocker surface  614  formed on a radius r 1  for line contact engagement of surface  602  of bearing adapter  600  formed on radius R 1 , r 1  being smaller than R 1 , and thus permitting longitudinal rocking to obtain passive self steering. As above, the resistance to rocking, and hence to self steering, may tend to be proportional to the weight on the rocker and hence may give proportional self steering when the car is either empty or loaded. Lower portion  612  also has an upper relief  616  that may be machined to a high level of flatness. Lower portion  612  also has a centrally located, integrally formed upwardly extending cylindrical stub  618  that stands perpendicularly proud of surface  616 . A bushing  620 , which may be a press fit bushing, mounts on stub  618 . 
     Rocker member  600  also has an upper portion  622  that has a second protruding male cylindrical rocker surface  624  formed on a radius r 2  for line contact engagement with the cylindrical surface  608  of trough  606 , formed on radius R 2 , thus permitting lateral rocking of sideframe  26 . Upper portion  622  may have a lower relief  626  for placement in opposition to relief  616 . Upper portion  622  has a centrally located blind bore  628  of a size for tight fitting engagement of bushing  620 , such that a close tolerance, pivoting connection is obtained that is largely compliant to pivotal motion about the vertical, or z, axis of upper portion  622  with respect to lower portion  612 . That is to say, the resistance to torsional motion about the z-axis is very small, and can be taken as zero for the purposes of analysis. To aid in this, bearing  630  may be installed about stub  618  and bushing  620  and is placed between opposed surfaces  606  and  616  to encourage relative rotational motion therebetween. 
     In this embodiment, stub  618  could be formed in upper portion  622 , and bore  618  formed in lower portion  612 , or, alternatively, bores  628  could be formed in both upper portion  612  and lower portion  622 , and a freely floating stub  618  and bushing  620  could be captured between them. It may be noted that the angular displacement about the z axis of upper portions  622  relative to lower portion  612  may be quite small—of the order of 1 degree, and may tend not to be even that large overly frequently. 
     Bearing adapter  600  may have longitudinally extending raised lateral abutment side walls  632  to discourage lateral migration, or escape of lower portion  612 . Lower portion  612  may have non-galling, relatively low co-efficient of friction side wear shim stock members  634  trapped between the end faces of lower portion  612  and side walls  632 . Bearing adapter  600  may also have a drain hole formed therein, possibly centrally, or placed at an angle. Similarly, pedestal seat fitting  604  may have laterally extending depending end abutment walls  636  to discourage longitudinal migration, or escape, of upper portion  622 . In a like manner to shim stock members  634 , non-galling, relatively low co-efficient of friction end wear shim stock members  638  may be mounted between the end faces of upper portion  622  and end abutment walls  636 . 
     In an alternative to the foregoing embodiment, the longitudinal cylindrical trough could be formed on the bearing adapter, and the lateral cylindrical trough could be formed in the pedestal seat, with corresponding changes in the entrapped rocker element. Further, it is not necessary that the male cylindrical portions be part of the entrapped rocker element. Rather, one of those male portions could be on the bearing adapter, and one of those male portions could be on the pedestal seat, with the corresponding female portions being formed on the entrapped rocker element. In the further alternative, the rocker element could include one male element, and one female element, having the male element formed on r 1  (or r 2 ) being located on the bearing adapter, and the female element formed on R 1  (or R 2 ) being on the underside of the entrapped rocker element, and the male element formed on r 2  (or r 1 ) being formed on the upper surface of the entrapped rocker element, and the respective mating female element formed on radius R 2  (or R 1 ) being formed on the lower face of the pedestal seat. In the still further alternative, the rocker element could include one male element, and one female element, having the male element formed on r 1  (or r 2 ) being located on the pedestal seat, and the female element formed on R 1  (or R 2 ) being on the upper surface of the entrapped rocker element, and the male element formed on r 2  (or r 1 ) being formed on the lower surface of the entrapped rocker element, and the respective mating female element formed on radius R 2  (or R 1 ) being formed on the upper face of the bearing adapter. There are, in this regard, at least eight combinations as represented in  FIG. 17   e  by assemblies  601 ,  603 ,  605 ,  607 ,  611 ,  613 ,  615 , and  617 . 
     The embodiment of  FIGS. 17   a - 17   d  may tend to yield line contact at the force transfer interfaces, and yet rock in both the longitudinal and lateral directions, with compliance to torsion about the vertical axis. That is, the bearing adapter to pedestal seat interface assembly may tend to permit rotation about the longitudinal axis to give lateral rocking motion of the side frame; rotation about a transverse axis to give longitudinal rocking motion; and compliance to torsion about the vertical axis. It may tend to discourage lateral translation, and may tend to retain high stiffness in the vertical direction. 
       FIGS. 18   a  and  18   b    
     The embodiment of  FIGS. 18   a  and  18   b  is substantially similar to the embodiment of  FIGS. 17   a  to  17   d . However, rather than employing a pivot connection such as the bore, stub, bushing and bearing of  FIGS. 17   a - 17   d , a rocker element  644  is captured between bearing adapter  600  and pedestal seat  604 . Rocker element  644  has a torsional compliance element made of a resilient material, identified as elastomeric member  646  bonded between the opposed faces of the upper  647  and lower  645  portions of rocker element  644 . Although  FIGS. 18   a  and  18   b  show the laterally extending trough in bearing adapter  600 , and the longitudinal trough in pedestal seat  604 , the same permutations of  FIG. 7   e  may be made. In general, while the torsional element may be between the two cylindrical elements in a manner tending torsionally to decouple them, it may be that the elastomeric pad need not necessarily be installed between the two cylindrical members. For example, the rocker element  644  may be solid, and an elastomeric element may be installed beneath the top surface of bearing adapter  600 , or above the pedestal seat element, such that a torsionally compliant element is placed in series with the two rockers. 
     The same general commentary may be made with regard to the pivotal connection suggested above in connection with the example of  FIGS. 17   a  to  17   d . That is, the top of the bearing adapter could be pivotally mounted to the body of the bearing adapter more generally, or the pedestal seat could be pivotally mounted to the pedestal roof, such that a torsionally compliant element would be in series with the two rockers. However, as noted above, the torsionally compliant element may be between the two rockers, such that they may tend to be torsionally de-coupled from each other. In general, with regard to the embodiments of  FIGS. 17   a - 17   d , and  18   a - 18   b , provided that the radii employed yield a physically appropriate combination tending toward a local stable minimum energy state, the male portion of the bearing adapter to pedestal seat interface (with the smaller radius of curvature) may be on either the bearing adapter or on the pedestal seat, and the mating female portion (with the larger radius of curvature) may be on the other part, whichever it may be. In that light, although a particular depiction may show a male portion on a bearing adapter, and a female fitting on the pedestal seat, these features may, in general, be reversed. 
       FIGS. 19   a  to  19   c ,  20   a  to  20   c , and  21   a  to  21   g    
       FIGS. 19   a  to  19   c  show the combination of a bearing adapter  650  with an elastomeric bearing adapter pad  652  and a rocker  654  and pedestal seat  656  to permit lateral rocking of the sideframe. Bearing adapter  650 , shown in three additional views in  FIGS. 20   a - 20   c  is substantially similar to bearing adapter  44  (or  144 ) to the extent of its geometric features for engaging a bearing, but differs therefrom in having a more or less conventional upper surface. Upper surface  658  may be flat, or may have a large (roughly 60″) radius crown  660 , such as might have been used for engaging a planar pedestal seat surface. Crown  660  is split into two fore-and-aft portions, with a laterally extending central flat portion between them. Abreast of the central flat portion, bearing adapter  650  has a pair of laterally proud, outwardly facing lateral lands,  662  and  664 , and, amidst those lands, lateral lugs  666  that extend further still proud beyond lands  662  and  664 . 
     Bearing adapter pad  652  may be a commercially available assembly such as may be manufactured by Lord Corporation of Erie Pa., or such as may be identified as Standard Car Truck Part Number SCT 5844. Bearing adapter pad  652  has a bearing adapter engagement member in the nature of a lower plate  668  whose bottom surface  670  is relieved to seat over crown  660  in non-rocking engagement. Lateral and longitudinal translation of bearing adapter pad  652  is inhibited by an array of downwardly bent securement locating lugs, or fingers, or claws, in the nature of indexing members or tangs  672 , two per side in pairs located to reach downwardly and bracket lugs  666  in close fitting engagement. The bracketing condition with respect to lugs  666  inhibits longitudinal motion between bearing adapter pad  652  and bearing adapter  650 . The laterally inside faces of tangs  672  closely oppose the laterally outwardly facing surfaces of lands  662  and  664 , tending thereby to inhibit lateral relative motion of bearing adapter pad  652  relative to bearing adapter  650 . The vertical, lateral, and longitudinal position relative to bearing adapter  650  can be taken as fixed. 
     Bearing adapter pad  652  also has an upper plate,  674 , that, in the case of a retro-fit installation of rocker  654  and seat  656 , may have been used as a pedestal seat engagement member. In any case, upper plate  674  has the general shape of a longitudinally extending channel member, with a central, or back, portion,  676  and upwardly extending left and right hand leg portions  678 ,  680  adjoining the lateral margins of back portion  676 . Leg portions  678  may have a size and shape such as might have been suitable for mounting directly to the sideframe pedestal. 
     Between lower plate  668  and upper plate  674 , bearing adapter pad  652  has a bonded resilient sandwich  680  that may include a first resilient layer, indicated as lower elastomeric layer  682  mounted directly to the upper surface of lower plate  668 , an intermediate stiffener shear plate  684  bonded or molded to the upper surface of layer  682 , and an upper resilient layer, indicated as upper elastomeric layer  686  bonded atop plate  684 . The upper surface of layer  686  may be bonded or molded to the lower surface of upper plate  674 . Given that the resilient layers may be quite thin as compared to their length and breadth, the resultant sandwich may tend to have comparatively high vertical stiffness, comparatively high resistance to torsion about the longitudinal (x) and lateral (y) axes, comparatively low resistance to torsion about the vertical (z) axis (given the small angular displacements in any case), and non-trivial, roughly equal resistance to shear in the x or y directions that may be in the range of 20,000 to 40,000 lbs per inch, or more narrowly, about 30,000 lbs per inch for small deflections. Bearing adapter pad  652  may tend to permit a measure of self steering to be obtained when the elastomeric elements are subjected to longitudinal shear forces. 
     Rocker  654  (seen in additional views  21   e ,  21   f  and  21   g ) has a body of substantially constant cross-section, having a lower surface  690  formed to sit in substantially flat, non-rocking engagement upon the upper surface of plate  674  of bearing adapter pad  652 , and an upper surface  692  formed to define a male rocker surface. Upper surface  692  may have a continuously radius central portion  694  lying between adjacent tangential portions  696  lying at a constant slope angle. In one embodiment, the central portion may describe 4-6 degrees of arc to either side of a central position, and may, in one embodiment have about 4½ to 5 degrees. In the terminology used above, this radius is “r 2 ”, the male radius of a lateral rocker for permitting lateral swinging motion of side frame  26 . Where a bearing adapter with a crown radius is mounted under the resilient bearing adapter pad, the radius of rocker  654  is less than the radius of the crown, perhaps less than half the crown radius, and possibly being less than ⅓ of the crown radius. It may be formed on a radius of between 5 and 20 inches, or, more narrowly, on a radius of between 8 and 15 inches. Surface  692  could also be formed on a parabolic profile, an elliptic or hyperbolic profile, or some other profile to yield lateral rocking. 
     Pedestal seat  656  (seen in  FIGS. 21   a  to  21   d ) has a body having a major portion  700  that is substantially rectangular in plan view. When viewed from one end in the longitudinal direction, pedestal seat  656  has a generally channel shaped cross-section, in which major portion  700  forms the back  702  and two longitudinally running legs  704 ,  706  extend upwardly and laterally outwardly from the lateral margins of major portion  700 . Legs  704  and  706  have an inner, or proximal portion  708  that extends upwardly and outwardly at an angle from the lateral margins of main portion  700 , and an outer, or distal portion, or toe  710  that extends from the end of proximal portion  708  in a substantially vertical direction. The breadth between the opposed fingers of the channel section (i.e., between opposed toes  710 ) corresponds to the width of the sideframe pedestal roof  712 , as shown in the cross-section of  FIG. 19   b , with which legs  704  and  706  sit in close fitting, bracketing engagement. Legs  704  and  706  have longitudinally centrally located cut-outs, reliefs, rebates, or indexing features, identified as notches  714 . Notches  714  seat in close fitting engagement about T-shaped lugs  716  ( FIG. 19   b ) that are welded to the sideframe on either side of the pedestal roof. This engagement establishes the lateral and longitudinal position of pedestal seat  656  with respect to sideframe  26 . 
     Pedestal seat  656  also has four laterally projecting corner lugs, or abutment fittings  718 , whose longitudinally inwardly facing surfaces oppose the laterally extending end-face surfaces of the upturned legs  678  of upper plate  674  of bearing adapter pad  652 . That is, the corner abutment fittings  718  on either lateral side of pedestal seat  656  bracket the ends of the upturned legs  678  of adapter pad  652  in close fitting engagement. This relationship fixes the longitudinal position of pedestal seat  656  relative to the upper plate of bearing adapter pad  652 . 
     Major portion  700  of pedestal seat  656  has a downwardly facing surface  700  that is hollowed out to form a depression defining a female rocking engagement surface  702 . This surface is formed on a female radius (identified as R 2  in concordance with terminology used herein above) that is quite substantially larger than the radius of central portion  694  ( FIG. 21   f ) of rocker  654 , such that rocker  654  and pedestal seat  656  meet in rolling line contact engagement and permit sideframe  26  to swing laterally in a lateral rocking relationship on rocker  654 . The arcuate profile of female rocking engagement surface  702  may be such as to encourage lateral self centering of rocker  654 , and may have a radius of curvature that varies from a central region to adjacent regions, which may be tangential planar regions. Where pedestal seat  656  and rocker  654  are provided by way of retro-fit installation above an adapter having a crown radius, the radius of curvature of the pedestal seat may tend to be less than or equal to the crown radius. The central radius of curvature R 2  of surface  702 , or the radius of curvature generally if constant, may be in the range of 6 to 60 inches, is preferably greater than 10 inches and less than 40 inches. It may be between 1 1/10 to 4 times as large as the rocker radius of curvature r 2 . As noted elsewhere, the pedestal seat need not have the female rocker surface, and the rocker need not have the male rocker surface, but rather, these surfaces could be reversed, so that the male surface is on the pedestal seat, and the female surface is on the rocker. Particularly in the context of a retro-fit installation, there may be relatively little clearance between the upturned legs  678  of upper plate  674  and legs  704 ,  706  of pedestal seat  656 . This distance is shown in  FIG. 19   b  as gap ‘G’, which is preferably sufficient allowance for rocking motion between the parts that rocking motion is bounded by the spacing of the truck bolster gibs  106 ,  108 . 
     By providing the combination of a lateral rocker and a shear pad, the resultant assembly may provide a generally increased softness in the lateral direction, while permitting a measure of self steering. The example of  FIG. 19   a  may be provided as an original installation, or may be provided as a retrofit installation. In the case of a retrofit installation, rocker  654  and pedestal seat  656  may be installed between an existing elastomeric pad and an existing pedestal seat, or may be installed in addition to a replacement elastomeric pad of lesser through-thickness, such that the overall height of the bearing adapter to pedestal seat interface may remain roughly the same as it was before the retrofit. 
       FIGS. 19   e  and  19   f  represent alternate embodiments of combinations of elastomeric pads and rockers. While the embodiment of  FIG. 19   a  showed an elastomeric sandwich that had roughly equivalent response to shear in the lateral and longitudinal directions, this need not be the general case. For example, in the embodiments of  FIGS. 19   e  and  19   f , elastomeric bearing adapter pad assemblies  720  and  731  have respective resilient elastomeric laminates sandwiches, indicated generally as  722  and  723  in which the stiffeners  726 ,  727  have longitudinally extending corrugations, or waves. In the longitudinal direction, the sandwich may tend to react in nearly pure shear, as before in the example of  FIG. 19   a . However, deflection in the lateral direction now requires not only a shear component, but also a component normal to the elastomeric elements, in compressive or tensile stress, rather than, and in addition to, shear. This may tend to give a stiffer lateral response, and hence an anisotropic response. An anisotropic shear pad arrangement of this nature might have been used in the embodiment of  FIG. 19   a , and a planar arrangement, as in the embodiment of  FIG. 19   a  could be used in either of the embodiments of  FIGS. 19   e , and  19   f . Considering  FIG. 19   e , both base plate  728  and upper plate  730  have a wavy contour corresponding to the wavy contour of sandwich  722  generally. Rocker  732  has a lower surface of corresponding profile. Otherwise, this embodiment is substantially the same as the embodiment of  FIG. 19   a.    
     Considering  FIG. 19   f , an elastomeric bearing adapter pad assembly  721  has a base plate  734  having a lower surface for seating in non-rocking relationship on a bearing adapter, in the same manner as bearing adapter pad assembly  652  sits upon bearing adapter  650 . The upper surface  735  of base plate  734  has a corrugated or wavy contour, the corrugations running lengthwise, as discussed above. An elastomeric laminate of a first resilient layer  736 , an internal stiffener plate  737 , and a second resilient layer  738  are located between base plate  734  and a correspondingly wavy undersurface of upper plate  740 . Rather than being a flat plate upon which a further rocker plate is mounted, upper plate  740  has an upper surface  742  having an integrally formed rocker contour corresponding to that of the upper surface of rocker  654 . Pedestal seat  744  then mounts directly to, and in lateral rocking relationship with upper plate  740 , without need for a separate rocker part. The combination of bearing adapter pad  721  and pedestal seat  742  may have interconnecting abutments  747  to prevent longitudinal migration of rocker surface  742  relative to the contoured downwardly facing surface  748  of pedestal seat  744 . 
       FIGS. 22   a  to  22   c ,  23   a  and  23   b    
     Rather than employ a bearing adapter that is separate from the bearing,  FIGS. 22   a  to  22   c  show a bearing  750  mounted on one of the end of an axle  752 . Bearing  750  has an integrally formed arcuate rolling contact surface  754  for mating rolling point contact with a mating rolling contact surface  756  of a pedestal seat fitting  758 . The general geometry of the rolling relationship is as described below in terms of the possible relationships of r 1 , R 1  and L, and, as noted above, the male and female rolling contact surfaces can be reversed, such that the male surface is on the pedestal seat, and the female surface is on the bearing, or further still, in the case of a compound curvature, the surfaces made be saddle shaped, as described above. The bearing illustrations of  FIGS. 22   b  and  23   b  are based on the bearing cross-section illustration shown on page 812 of the 1997 Car and Locomotive Cyclopedia. That illustration was provided to the Cyclopedia courtesy of Brenco Inc., of Petersburg, Va. 
     In greater detail, bearing  750  is an assembly of parts including an inner ring  760 , a pair of tapered roller assemblies  762  whose inner ring engages axle  752 , and an outer ring member  764  whose inner frustoconical bearing surfaces engage the rollers of assemblies  762 . The entire assembly, including seals, spacers, and backing ring is held in place by an end cap  766  mounted to the end of axle  752 . In the assembly of  FIGS. 22   a  to  22   c , does not employ a round cylindrical outer ring member, but rather, ring member  764  is made with an upper portion  770  having the same general shape and function as bearing adapter  44  or  144 , including tapered end walls  768  for rocking motion travel limiting abutment against the surfaces of the pedestal jaws  130  as described above. Further, upper portion  770  includes corner abutments  774  for bracketing jaws  130 , again, as described above. Thus a bearing is provided with an integrally formed rocking surface. The rocking surface is permanently fixed with relation to the remainder of the underlying bearing assembly. In this way, an assembly is provided in which rotation of the bearing housing is inhibited relative to the rocking surface. 
     In  FIGS. 23   a  and  23   b , an integrated bearing and bearing adapter rocker assembly, or wheelset to pedestal interface assembly, is indicated as modified bearing  790 . In this case the outer ring  792  has been formed in the shape of a laterally extending, cylindrical rocker surface  794 , such as a male surface (although it could be female as discussed above), for engaging the mating female (although, as discussed, it could be male) laterally rocker surface  796  of pedestal seat  798 , such as may tend to provide weight-proportional self steering, as discussed above. 
     Thus, the embodiments of  FIGS. 22   a  and  23   a  both show a sideframe pedestal to axle bearing interface assembly for a three piece rail road car truck. The assembly of the embodiment of  FIG. 22   a  has fittings that are operable to rock both laterally and longitudinally. Both embodiments include bearing assemblies having one of the rocking surface fittings, whether male or female, of saddle shape, formed as an integral portion of the outer ring of the bearing, such that the location of the rolling contact surface is rigidly located relative to the bearing (because, in this instance, it is part of the bearing). In the embodiment of  FIG. 22   a , the integrally firmed surface is a compound surface, whereas in the embodiment of  FIG. 23   b , the rolling contact surface is a cylindrical surface, which may be formed on an arc of constant radius of curvature. 
     The possible permutations of surface types include those indicated above in terms of a two element interface (i.e., the rocking surface on the top of the bearing, and the mating rocking surface on the pedestal seat) or a three element interface, in which an intermediate rocking member is mounted between (a) the surface rigidly located with respect to the bearing races, and (b) the surface of the pedestal seat. As above, one or another of the surfaces may be formed on a spherical arc portion such that the fittings are torsionally compliant, or, put alternatively, torsionally de-coupled with respect to rotation about the vertical axis. The permutations may also include the use of resilient pads such as members  156 ,  374 ,  412 , or  456 , as may be appropriate. 
     Each of the assemblies of  FIGS. 22   a  and  23   a  has a bearing for mounting to one end of an axle of a wheelset of a three-piece railroad car truck. The bearing has an outer member mounted in a position to permit the end of the axle to rotate relative thereto, inasmuch as the inner ring is intended to rotate with respect to the outer ring. The bearing has an axis of rotation, about which its rings and bearings are concentric that, when installed, may tend to be coincident with the longitudinal axis of the axis of the axle of the wheelset. In each case, the outer member has a rocking surface formed thereon for engaging a mating rolling contact surface of a pedestal seat member of a sideframe of the three piece truck. 
     The rolling contact surface of the bearing has a local minimum energy condition when centered under the corresponding seat, and it is preferred that the mating rolling contact surface be given a radius that may tend to encourage self centering of the male rolling contact element. That is to say, displacement from the minimum energy position (preferably the centered position) may tend to cause the vertical separation distance between the centerline of the wheelset axis (and hence the centerline of the axis of rotation of the bearing) to become more distantly spaced from the sideframe pedestal roof, since the rocking action may tend marginally to raise the end of the sideframe, thus increasing the stored potential energy in the system. 
     This can be expressed differently. In cylindrical polar co-ordinates, the long axis of the wheelset axle may be considered as the axial direction. There is a radial direction measured perpendicularly away from the axial direction, and there is an angular circumferential direction that is mutually perpendicular to both the axial direction, and the radial direction. There is a location on the rolling contact surface that is closer to the axis of rotation of the bearing than any other location. This defines the “rest” or local minimum potential energy equilibrium position. Since the radius of curvature of the rolling contact surface is greater than the radial length, L, between the axis of rotation of the bearing and the location of minimum radius, the radial distance, as a function of circumferential angle θ will increase to either side of the location of minimum radius (or, put alternatively, the location of minimum radial distance from the axis of rotation of the bearing lies between regions of greater radial distance). Thus the slope of the function r(θ), namely dr/dθ, is zero at the minimum point, and is such that r increases at an angular displacement away from the minimum point to either side of the location of minimum potential energy. Where the surface has compound curvature, both dr/dθ and dr/dL are zero at the minimum point, and are such that r increases to either side of the location of minimum energy to all sides of the location of minimum energy, and zero at that location. This may tend to be true whether the rolling contact surface on the bearing is a male surface or a female surface or a saddle, and whether the center of curvature lies below the center of rotation of the bearing, or above the rolling contact surfaces. The curvature of the rolling contact surface may be spherical, ellipsoidal, toroidal, paraboloid, parabolic or cylindrical. The rolling contact surface has a radius of curvature, or radii of curvature, if a compound curvature is employed, that is, or are, larger than the distance from the location of minimum distance from the axis of rotation, and the rolling contact surfaces are not concentric with the axis of rotation of the bearing. 
     Another way to express this is to note that there is a first location on the rolling contact surface of the bearing that lies radially closer to the axis of rotation of the bearing than any other location thereon. A first distance, L is defined between the axis of rotation, and that nearest location. The surface of the bearing and the surface of the pedestal seat each have a radius of curvature and mate in a male and female relationship, one radius of curvature being a male radius of curvature r 1 , the other radius of curvature being a female radius of curvature, R 2 , (whichever it may be). r 1  is greater than L, R 2  is greater than r 1 , and L, r 1  and R 2  conform to the formula L −1 −(r 1   −1 −R 2   −1 )&gt;0, the rocker surfaces being co-operable to permit self steering. 
       FIGS. 24   a  to  24   e    
       FIGS. 24   a  to  24   e  relate to a three piece truck  200 . Truck  200  has three major elements, those elements being a truck bolster  192 , that is symmetrical about the truck longitudinal centerline, and a pair of first and second side frames, indicated as  194 . Only one side frame is shown in  FIG. 14   c  given the symmetry of truck  200 . Three piece truck  200  has a resilient suspension (a primary suspension) provided by a spring group  195  trapped between each of the distal (i.e., transversely outboard) ends of truck bolster  192  and side frames  194 . 
     Truck bolster  192  is a rigid, fabricated beam having a first end for engaging one side frame assembly and a second end for engaging the other side frame assembly (both ends being indicated as  193 ). A center plate or center bowl  190  is located at the truck center. An upper flange  188  extends between the two ends  194 , being narrow at a central waist and flaring to a wider transversely outboard termination at ends  194 . Truck bolster  192  also has a lower flange  189  and two fabricated webs  191  extending between upper flange  188  and lower flange  189  to form an irregular, closed section box beam. Additional webs  197  are mounted between the distal portions of flanges  188  and  189  where bolster  192  engages one of the spring groups  195 . The transversely distal region of truck bolster  192  also has friction damper seats  196 ,  198  for accommodating friction damper wedges. 
     Side frame  194  may be a casting having pedestal fittings  40  into which bearing adapters  44 , bearings  46 , and a pair of axles  48  and wheels  50  mount. Side frame  194  also has a compression member, or top chord member  32 , a tension member, or bottom chord member  34 , and vertical side columns  36  and  36 , each lying to one side of a vertical transverse plane bisecting truck  200  at the longitudinal station of the truck center. A generally rectangular opening is defined by the co-operation of the upper and lower beam members  32 ,  34  and vertical sideframe columns  36 , into which end  193  of truck bolster  192  can be introduced. The distal end of truck bolster  192  can then move up and down relative to the side frame within this opening. Lower beam member  34  has a bottom or lower spring seat  52  upon which spring group  195  can seat. Similarly, an upper spring seat  199  is provided by the underside of the distal portion of bolster  192  which engages the upper end of spring group  195 . As such, vertical movement of truck bolster  192  will tend to increase or decrease the compression of the springs in spring group  195 . 
     In the embodiment of  FIG. 24   a , spring group  195  has two rows of springs  193 , a transversely inboard row and a transversely outboard row. In one embodiment each row may have four large (8 inch +/−) diameter coil springs giving vertical bounce spring rate constant, k, for group  195  of less than 10,000 lbs./inch. In one embodiment this spring rate constant may be in the range of 6000 to 10,000 lbs./in., and may be in the range of 7000 to 9500 lbs./in, giving an overall vertical bounce spring rate for the truck of double these values, perhaps in the range of 14,000 to 18,500 lbs./in for the truck. The spring array may include nested coils of outer springs, inner springs, and inner-inner springs depending on the overall spring rate desired for the group, and the apportionment of that stiffness. The number of springs, the number of inner and outer coils, and the spring rate of the various springs can be varied. The spring rates of the coils of the spring group add to give the spring rate constant of the group, typically being suited for the loading for which the truck is designed. 
     Each side frame assembly also has four friction damper wedges arranged in first and second pairs of transversely inboard and transversely outboard wedges  204 ,  205 ,  206  and  207  that engage the sockets, or seats  196 ,  198  in a four-cornered arrangement. The corner springs in spring group  195  bear upon a friction damper wedge  204 ,  205 ,  206  or  207 . Each vertical column  36  has a friction wear plate  92  having transversely inboard and transversely outboard regions against which the friction faces of wedges  204 ,  205 ,  206  and  207  can bear, respectively. Bolster gibs  106  and  108  lie inboard and outboard of wear plate  92  respectively. 
     In the illustration of  FIG. 24   e , the damper seats are shown as being segregated by a partition  208 . If a longitudinal vertical plane is drawn through truck  200  through the center of partition  208 , it can be seen that the inboard dampers lie to one side of plane  209 , and the outboard dampers lie to the outboard side of the plane. In hunting then, the normal force from the damper working against the hunting will tend to act in a couple in which the force on the friction bearing surface of the inboard pad will always be fully inboard of the plane on one end, and fully outboard on the other diagonal friction face. 
     In one embodiment, the size of the spring group embodiment of  FIG. 24   b  may yield a side frame window opening having a width between the vertical columns  36  of side frame  194  of roughly 33 inches. This is relatively large compared to existing spring groups, being more than 25% greater in width. In the embodiment of  FIG. 1   f  truck  20  may also have an abnormally wide sideframe window to accommodate 5 coils each of 5½″ dia. Truck  200  may have a correspondingly greater wheelbase length, indicated as WB. WB may be greater than 73 inches, or, taken as a ratio to the track gauge width, may be greater than 1.30 time the track gauge width. It may be greater than 80 inches, or more than 1.4 times the gauge width, and in one embodiment is greater than 1.5 times the track gauge width, being as great, or greater than, about 84 inches. Similarly, the side frame window may be wider than tall. The measurement across the wear plate faces between the opposed side frame columns  36  may be greater than 24″, possibly in the ratio of greater than 8:7 of width to height, and possibly in the range of 28″ or 32″ or more, giving ratios of greater than 4:3 and greater than 3:2. The spring seat may have lengthened dimensions to correspond to the width of the side frame window, and a transverse width of 15½-17″ or more. 
       FIGS. 25   a  to  25   d    
       FIGS. 25   a  to  25   d , show an alternate truck embodiment. Truck  800  has a bolster  808 , side frame  807  and damper  801 ,  802  installation that employs constant force inboard and outboard, fore and aft pairs of friction dampers  801 ,  802  independently sprung on horizontally acting springs  803 ,  804  housed in side-by-side pockets  805 ,  806  mounted in the ends of truck bolster  808 . While only two dampers  801 ,  802  are shown, a pair of such dampers faces toward each of the opposed side frame columns. Dampers  801 ,  802  may each include a block  809  and a consumable wear member  810  mounted to the face of block  809 . The block and wear member have mating male and female indexing features  812  to maintain their relative position. A removable grub screw fitting  814  is provided in the spring housing to permit the spring to be pre-loaded and held in place during installation. Springs  803 ,  804  urge, or bias, friction dampers  801 ,  802  against the corresponding friction surfaces of the sideframe columns. The deflection of springs  803 ,  804  does not depend on compression of the main spring group  816 , but rather is a function of an initial pre-load. 
       FIGS. 26   a  and  26   b    
       FIGS. 26   a  and  26   b  show a partial isometric view of a truck bolster  820  that is generally similar to truck bolster  402  of  FIG. 14   a , except insofar as bolster pocket  822  does not have a central partition like web  452 , but rather has a continuous bay extending across the width of the underlying spring group, such as spring group  436 . A single wide damper wedge is indicated as  824 . Damper  824  is of a width to be supported by, and to be acted upon, by two springs  825 ,  826  of the underlying spring group. In the event that bolster  400  may tend to deflect to a non-perpendicular orientation relative to the associated side frame, as in the parallelogramming phenomenon, one side of wedge  824  may tend to be squeezed more tightly than the other, giving wedge  824  a tendency to twist in the pocket about an axis of rotation perpendicular to the angled face (i.e., the hypotenuse face) of the wedge. This twisting tendency may also tend to cause differential compression in springs  825 ,  826 , yielding a restoring moment both to the twisting of wedge  824  and to the non-square displacement of truck bolster  820  relative to the truck side frame. There may tend to be a similar moment generated at the opposite spring pair at the opposite side column of the side frame.  FIG. 26   b  shows an alternate pair of damper wedges  827 ,  828 . This dual wedge configuration can similarly seat in bolster pocket  822 , and, in this case, each wedge  827 ,  828  sits over a separate spring. Wedges  827 ,  828  are slidable relative to each other along the primary angle of the face of bolster pocket  822 . When the truck moves to an out of square condition, differential displacement of wedges  827 ,  828  may tend to result in differential compression of their associated springs, e.g.,  825 ,  826  resulting in a restoring moment. In either case, the bolster pockets may have wear liners  494 , and the pockets themselves may be part of prefabricated inserts  506  to be welded to the end of the bolster, either at original manufacture or retro-fit, such as might include installation of wider sideframe columns, and a different spring group selection such as might accompany a retrofit conversion from a single damper to a double damper (i.e., four cornered) arrangement. 
       FIGS. 27   a  and  27   b    
       FIG. 27   a  shows a bolster  830  that is similar to bolster  210  except insofar as bolster pockets  831 ,  832  each accommodate a pair of split wedges  833 ,  834 . Pockets  831 ,  832  each have a pair of bearing surfaces  835 ,  836  that are inclined at both a primary angle α and a secondary angle β, the secondary angles of surfaces  835  and  836  being of opposite hand to yield the damper separating forces discussed above. Surfaces  835  and  836  are also provided with linings in the nature of relatively low friction wear plates  837 ,  838 . Each pair of split wedges seats over a single spring. 
     The example of  FIG. 27   b  shows a combination of a bolster  840  and biased split wedges  841 ,  842 . Bolster pockets  843 ,  844  are stepped pockets in which the steps, e.g., items  845 ,  846 , have the same primary angle α, and the same secondary angle β, and are both biased in the same direction, unlike the symmetrical faces of the split wedges in  FIG. 27   a , which are left and right handed. Thus the outboard pair of split wedges  842  has first and second members  847 ,  848  each having primary angle α and secondary angle β of the same hand, both members being biased in the outboard direction. Similarly, the inboard pair of split wedges  841  has first and second members  849 ,  850  having primary angle α, and secondary angle β, except that the sense of secondary angle β is such that members  849  and  850  tend to be driven in the inboard direction. In the arrangement of  FIG. 27   c  a single stepped wedge  851 ,  852  may be used in place of the pair of split wedges e.g., members  847 ,  848  or  849 ,  850 . A corresponding wedge of opposite hand is used in the other bolster pocket. 
       FIGS. 28   a  and  28   b    
     In  FIG. 28   a , a truck bolster  860  has welded bolster pocket inserts  861 ,  862  of opposite hands welded into accommodations in its end. Each bolster pocket has inboard and outboard portions  863 ,  864  that share the same primary angle α, but have secondary angles β that are of opposite hand. Respective inboard and outboard wedges are indicated as  865 ,  866 , each seating over a vertically oriented spring  867 ,  868 . In this case bolster  860  is similar to bolster  820  of  FIG. 26   a , to the extent that there is no land separating the inner and outer portions of the bolster pocket. Bolster  860  is also similar to bolster  210  of  FIG. 5 , except that the bolster pockets of opposite hand are merged without an intervening land. In  FIG. 28   b , split wedge pairs  869 ,  870  (inboard) and  871 ,  872  (outboard) are employed in place of the single inboard and outboard wedges  865  and  866 . 
       FIGS. 29   a - 29   c    
       FIGS. 29   a - 29   c  illustrate an alternate embodiment of bolster gib and sideframe inter-relationship, such as may be incorporated in a truck such as truck  20 , or  22 , or other truck shown or described herein. In the embodiment of  FIGS. 29   a - 29   c , truck  900  has a bolster  902  and sideframes  904 . It may be that a type or railroad freight car, such as a coal car, in which truck  900  might be employed, for example, may be operated in the light car (i.e., empty) condition, as when being returned to a location for loading once again with lading. Such a car, or string of such cars, may be dragged or pushed in the empty condition on not necessarily the best track, with relatively sharp curves. In such a condition, the lateral forces imposed on the truck may be proportionately great relative to the vertical force on the truck due to gravity acting on the car. The ratio of these forces is sometimes referred to as the L/V ratio. In such circumstances it may be appropriate to have a relatively small allowance for lateral travel of the bolster relative to the sideframes. With a fully laden car, however, the L/V ratio may be low, or lower, and a tight bolster gib spacing may not yield the most desirable result with respect to wear on the rails. A wider gib spacing for a fully laden car may permit a larger lateral excursion before contact occurs between the bolster gib and sideframe, and so may yield a more desirable overall ride quality. 
     Truck  900  may have one of the sideframe to wheelset interface assemblies of one or another of the embodiments described herein, which, as noted, may include a lateral rocking fitting. Bolster  902  may have at each end thereof, and on each fore and aft face thereof (being symmetrical about its central axis and being symmetrical about its long axis) an inboard bolster gib  906 , and an outboard bolster gib  908 . Inboard bolster gib  906  may be mounted inboard of the most laterally inboard portion of the bolster damper pockets  910 , and outboard bolster gib  908  may be mounted outboard of the most outboard portion of the bolster pocket,  912 , and may be mounted to the distal extremity of bolster  902 . Although truck  900  may have a four cornered damper, or double damper, arrangement as in truck  20  or  22 , a tapered gib arrangement such as here described, may be employed with a single damper installation, as in truck  250  of  FIG. 1   e.    
     Inboard gib  906  may have a body  914  extending generally perpendicularly away from the front face web  916  of bolster  902 , and may have an abutment surface  918  facing toward the sideframe column  920 , and, more specifically, toward a stop identified as a sideframe column abutment face  922  that lies on the laterally inboard margin of the reinforced wear plate backing frame portion  924  of sideframe column  920 . When viewed in profile, (that is to say looking parallel to the long axis of the sideframe), abutment surface  918  may be inclined, and may be inclined linearly, such as at an angle gamma, y, from the vertical on a slope that extends upward and inboard, downward and outboard. Similarly, abutment face  922  may also be relieved at angle gamma y. As the vertical deflection of the spring group  915  increases, the lateral translational gap, i.e., the gap measured on the horizontal plane, of the light car condition, indicated in  FIG. 29   c  as ‘G 1 ’ as the horizontal distance between surface  918  and surface  922 , may also tend to increase such that the clearance may differ for different at rest positions of the bolster according to the amount of lading carried by the car as indicated by the larger lateral dimension of the gap, indicated as ‘G 2 ’ in  FIG. 29   d . The lateral translational gap ‘G 2 ’ may correspond to the gap size in the at rest position of a fully laden car. ‘G 2 ’ and ‘G 1 ’ are measures of allowance for lateral translation of the bolster relative to the sideframe, and in some embodiments may be related to the vertical spring displacement between two, G 2 =G 1 +δ spring  tan γ. In the instance where the opposed surfaces are planar and parallel, the gap width normal to the opposed surfaces are G 2  Cos γ or G 1  Cos γ respectively. In operation, lateral translation of bolster  902  relative to sideframe  904  may tend to urge surfaces  916  and  920  toward (or away) from each other, with the limit of travel being reached when they abut. As may be appreciated, lateral travel in one direction may cause abutting contact with the gib stop on one sideframe, while lateral travel in the opposite direction may yield abutting contact with the gib stop on the other sideframe such that the lateral travel is bounded in both directions. The upper or lower, or both, vertices of surface  918  may have relatively generous radii  925 . 
     It may be that the at rest spacing ‘P’ of the outboard bolster gib may be comparable to, or slightly greater than, the at rest spacing of the inboard gib from the stop on the sideframe at the fully laden condition. That is, dimension ‘P’ may be greater than dimension ‘G 2 ’ when bolster  902  is in its at rest position in the fully laden condition. In one embodiment, ‘P’ may be in the range of 1 to 1⅜ inches, and may be about 1¼ inches. In one embodiment ‘G 1 ’ may be in the range of ⅜ to ⅝ inches, and may be about ½ inch in the light car condition, and ‘G 2 ’ may be in the range of 1 inch to 1¼ inches in the fully laden condition, and may be in the range of 1¼ to 1½ inches, and may be about 1⅜ inches in the full travel “solid” condition of the spring group. In some embodiments the outboard gib  908  may have a vertical, planar abutment surface as illustrated in  FIGS. 29   a  to  29   d , and may serve primarily to prevent escape of sideframe  904  from bolster  902 . In other embodiments outboard gib  908  may also have a tapered abutment contact surface  926  as illustrated in  FIG. 29   e  in the manner of gib  906 , and the outboard abutment surface or stop  928  of sideframe column  920  may also be tapered. 
     Angle gamma, γ, may lie in the range of about tan−1 (1 1/16) to tan−1 ( 2/16), or, alternatively, about 5 degrees to about 40 degrees, and in one embodiment the incremental slope relating increased lateral spacing to increased at rest deflection of the main spring groups may be about 7/16 inches of additional travel per inch of additional vertical deflection, (+/−25%). 
     Although the embodiments of  FIGS. 29   a - 29   d  may employ gibs and mating, co-operation stops of identical profiles, being mating positive and negative images such as surfaces  918  and  922 , this need not necessarily be so. In another embodiment, as shown in  FIG. 29   f , an abutment may have a non-straight edge form, as indicated by arcuate surface  930 , which may follow a circular or parabolic arc for contact with a mating face, such as linear face  932 . The arc may have a local radius of curvature Ro. The arcuate surface  930  may be formed such that the point of tangency (when abutting the stop) is at the mid point of the arc. It may also be understood that the arcuate surface is formed on the sideframe column, while the other surface could be formed on the gib, i.e., the relationship could be reversed. 
       FIGS. 30   a - 30   g    
     An alternate form of damper assembly  940  is illustrated in  FIGS. 30   a  to  30   g . Damper assembly  940  may include a wedge body  942  and a friction member  944  matingly engageable with body  942 . In this instance, friction member  944  may be a replaceable member that seats in a forwardly facing socket  946  formed in body  942 . Although socket  946  may have a female form, and friction member  944  may have a corresponding male form, this could be reversed, with the illustrations of  FIGS. 30   a  to  30   g  being intended to be generically representative in this regard, without the need for duplication of the drawings in the reversed male and female roles. Friction member  944  may have a rearwardly protruding bulge having an engagement interface surface  948  that is formed on a body of revolution, and that may have a compound curvature with radii of curvature about both an horizontal axis ‘y’ and a vertical axis ‘z’. Socket  946  may have a mating engagement interface surface  950  of complementary compound curvature. Furthermore, either or both of surfaces  948  and  950  may be treated to reduce friction therebetween, as by applying a polymeric or other sliding surface layer or treatment. A lubricant, which may be a solid lubricant, may be used between surfaces  948  and  950  as may a coating, such as an anti-galling coating. 
     To the extent that the bolster may flex to a non-square condition with respect to the sideframe columns, or to the extent that there may be a relative rise or fall between the leading and trailing wheels of the sideframe such that the sideframe rotates about the long axis of the truck bolster, friction member  944  may tend to be urged to pitch or yaw relative to the bolster, while maintaining friction face  952  in planar contact with the opposing sideframe column wear plate. The use of mating curvatures on surfaces  948  and  950 , which may be mating spherical curvatures, may give degrees of freedom of rotation about the ‘y’ and ‘z’ axes to accommodate a measure of angular displacement of friction member  944  relative to body  942  under those pitch and yaw conditions. The hypotenuse face  954  of body  942  may be planar (that is, it may lack the crown discussed hereinabove), and may have primary and secondary angles as discussed above. The base, or spring seat socket side  960  of body  942  may be as above, and may have a skirt, or skirt array of depending members  961 ,  962 ,  963  for capturing the upper end of a spring, such as indicated as  938 . Friction member  944  may be formed of a compound having known friction properties friction properties throughout, or may have a back portion  956  for seating against body  942 , and a front portion, or friction face portion  958  as it may be termed, that may be a layer or pad having known friction properties such as those types of coatings, or surfaces or pads described elsewhere herein. The front and back portions  958 ,  956  may be releaseably engageable, or releaseably mutually interlocking, or, alternatively, may be cast or bonded together in a permanent or substantially permanent manner. Body  942  may also have spaced apart, parallel planar side faces  964 ,  966 , that may slide in planar relationship against an end face of the corresponding bolster pocket. While face portion  958  may have a circular friction face  952 , it could also be extended to have a non-circular face, such as generally square or rectangular contact footprint against the sideframe column wear plate, such as when the compound curvature has different radii of curvature about the z any y axes. In use, when the friction compound, for example, portion  958 , has been worn away in large measure, be it ½, ⅔, ¾ of the original material being worn away, or some other wear criteria having been surpassed, then friction member  944  may be extracted during servicing and a new or re-built friction member  944  may be installed instead. 
     Compound Pendulum Geometry 
     The various rockers shown and described herein may employ rocking elements that define compound pendulums—that is, pendulums for which the male rocker radius is non-zero, and there is an assumption of rolling (as opposed to sliding) engagement with the female rocker. The embodiment of  FIG. 2   a  (and others) for example, shows a bi-directional compound pendulum. The performance of these pendulums may affect both lateral stiffness and self-steering on the longitudinal rocker. 
     The lateral stiffness of the suspension may tend to reflect the stiffness of (a) the sideframe between (i) the bearing adapter and (ii) the bottom spring seat (that is, the sideframes swing laterally); (b) the lateral deflection of the springs between (i) the lower spring seat and (ii) the upper spring seat mounting against the truck bolster, and (c) the moment between (i) the spring seat in the sideframe and (ii) the upper spring mounting against the truck bolster. The lateral stiffness of the spring groups may be approximately ½ of the vertical spring stiffness. For a 100 or 110 Ton truck designed for 263,000 or 286,000 lbs GRL, vertical spring group stiffness might be 25-30,000 lbs./in., assuming two groups per truck, and two trucks per car, giving a lateral spring stiffness of 13-16,000 lbs./in. The second component of stiffness relates to the lateral rocking deflection of the sideframe. The height between the bottom spring seat and the crown of the bearing adapter might be about 15 inches (+/−). The pedestal seat may have a flat surface in line contact on a 60 inch radius bearing adapter crown. For a loaded 286,000 lbs. car, the apparent stiffness of the sideframe due to this second component may be 18,000-25,000 lbs./in, measured at the bottom spring seat. Stiffness due to the third component, unequal compression of the springs, is additive to sideframe stiffness. 
     An alternate truck is the “Swing Motion” truck, such as shown at page 716 in the 1980 Car and Locomotive Cyclopedia (1980, Simmons-Boardman, Omaha). In a swing motion truck, the sideframe may act more like a pendulum. The bearing adapter may have a female rocker, of perhaps 10 in. radius. A mating male rocker mounted in the pedestal roof may have a radius of perhaps 5 in. Depending on the geometry, this may yield a sideframe resistance to lateral deflection in the order of ¼ (or less) to about ½ of what might otherwise be typical. If combined with the spring group stiffness, the relative softness of the pendulum may be dominant. Lateral stiffness may then be less governed by vertical spring stiffness. Use of a rocking lower spring seat may reduce, or eliminate, lateral stiffness due to unequal spring compression. Swing motion trucks have used transoms to link the side frames, and to lock them against non-square deformation. Other substantially rigid truck stiffening devices such as lateral unsprung rods or a “frame brace” of diagonal unsprung bracing have been used. Lateral unsprung bracing may increase resistance to rotation of the sideframes about the long axis of the truck bolster. This may not necessarily enhance wheel load equalization or discourage wheel lift. 
     A formula may be used for estimation of truck lateral stiffness:
 
 k   truck =2×[( k   sideframe ) −1 +( k   spring shear ) −1 ] −1  
 
     where
         k sideframe =[k pendulum +k spring moment ]   k spring shear =The lateral spring constant for the spring group in shear.   k pendulum =The force required to deflect the pendulum per unit of deflection, as measured at the center of the bottom spring seat.   k spring moment =The force required to deflect the bottom spring seat per unit of sideways deflection against the twisting moment caused by the unequal compression of the inboard and outboard springs.       

     In a pendulum, the relationship of weight and deflection is roughly linear for small angles, analogous to F=kx, in a spring. A lateral constant can be defined as k pendulum =W/L, where W is weight, and L is pendulum length. An approximate equivalent pendulum length can be defined as L eq =W/k pendulum . W is the sprung weight on the sideframe. For a truck having L=15 and a 60″ crown radius, L eq  might be about 3 in. For a swing motion truck, L eq  may be more than double this. 
     A formula for a longitudinal (i.e., self-steering) rocker as in  FIG. 2   a , may also be defined:
 
 F/δ   long   =k   long =( W/L )[[(1 /L )/(1 /r   1 −1 /R   1 )]−1]
 
     Where: 
     k long  is the longitudinal constant of proportionality between longitudinal force and longitudinal deflection for the rocker. 
     F is a unit of longitudinal force, applied at the centerline of the axle 
     δ long  is a unit of longitudinal deflection of the centerline of the axle 
     L is the distance from the centerline of the axle to the apex of male portion  116 . 
     R 1  is the longitudinal radius of curvature of the female hollow in the pedestal seat  38 . 
     r 1  is the longitudinal radius of curvature of the crown of the male portion  116  on the bearing adapter 
     In this relationship, R 1  is greater than r 1 , and (1/L) is greater than [(1/r 1 )−(1/R 1 )], and, as shown in the illustrations, L is smaller than either r 1  or R 1 . In some embodiments herein, the length L from the center of the axle to apex of the surface of the bearing adapter, at the central rest position may typically be about 5¾ to 6 inches (+/−), and may be in the range of 5-7 inches. Bearing adapters, pedestals, side frames, and bolsters are typically made from steel. The present inventor is of the view that the rolling contact surface may preferably be made of a tool steel, or a similar material. 
     In the lateral direction, an approximation for small angular deflections is:
 
 k   pendulum =( F   2 /δ 2 )=( W/L   pend. )[[(1 /L   pend. )/((1 /R   Rocker )−(1 /R   Seat ))]+1]
 
     where: 
     k pendulum =the lateral stiffness of the pendulum 
     F 2 =the force per unit of lateral deflection applied at the bottom spring seat 
     δ 2 =a unit of lateral deflection 
     W=the weight borne by the pendulum 
     L pend. =the length of the pendulum, as undeflected, between the contact surface of the bearing adapter to the bottom of the pendulum at the spring seat 
     R Rocker =r 2 =the lateral radius of curvature of the rocker surface 
     R Seat =R 2 =the lateral radius of curvature of the rocker seat 
     Where R Seat  and R Rocker  are of similar magnitude, and are not unduly small relative to L, the pendulum may tend to have a relatively large lateral deflection constant. Where R Seat  is large compared to L or R Rocker , or both, and can be approximated as infinite (i.e., a flat surface), this formula simplifies to:
 
 k   pendulum =( F   lateral /δ lateral )=( W/L   pend. )[( R   Rocker   /L   pendulum )+1]
 
     Using this number in the denominator, and the design weight in the numerator yields an equivalent pendulum length, L eq. =W/k pendulum    
     The sideframe pendulum may have a vertical length measured (when undeflected) from the rolling contact interface at the upper rocker seat to the bottom spring seat of between 12 and 20 inches, perhaps between 14 and 18 inches. The equivalent length L eq , may be in the range of greater than 4 inches and less than 15 inches, and, more narrowly, 5 inches and 12 inches, depending on truck size and rocker geometry. Although truck  20  or  22  may be a 70 ton special, a 70 ton, 100 ton, 110 ton, or 125 ton truck, truck  20  or  22  may be a truck size having 33 inch diameter, or 36 or 38 inch diameter wheels. In some embodiments herein, the ratio of male rocker radius R Rocker  to pendulum length, L pend. , may be 3 or less, in some instances 2 or less. In laterally quite soft trucks this value may be less than 1. The factor [(1/L pend. )/((1/R Rocker )−(1/R Seat ))], may be less than 3, and, in some instances may be less than 2½. In laterally quite soft trucks, this factor may be less than 2. In those various embodiments, the lateral stiffness of the lateral rocker pendulum, calculated at the maximum truck capacity, or the GRL limit for the railcar more generally, may be less than the lateral shear stiffness of the associated spring group. Further, in those various embodiments the truck may be free of lateral unsprung bracing, whether in terms of a transom, laterally extending parallel rods, or diagonally criss-crossing frame bracing or other unsprung stiffeners. In those embodiments the trucks may have four cornered damper groups driven by each spring group. 
     In the trucks described herein, for their fully laden design condition which may be determined either according to the AAR limit for 70, 100, 110 or 125 ton trucks, or, where a lower intended lading is chosen, then in proportion to the vertical sprung load yielding 2 inches of vertical spring deflection in the spring groups, the equivalent lateral stiffness of the sideframe, being the ratio of force to lateral deflection, measured at the bottom spring seat, may be less than the horizontal shear stiffness of the springs. In some embodiments, particularly for relatively low density fragile, high valued lading such as automobiles, consumer goods, and so on, the equivalent lateral stiffness of the sideframe k sideframe  may be less than 6000 lbs./in. and may be between about 3500 and 5500 lbs./in., and perhaps in the range of 3700-4100 lbs./in. For example, in one embodiment a 2×4 spring group has 8 inch diameter springs having a total vertical stiffness of 9600 lbs./in. per spring group and a corresponding lateral shear stiffness k spring shear  of 8200 lbs./in. The sideframe has a rigidly mounted lower spring seat. It may be used in a truck with 36 inch wheels. In another embodiment, a 3×5 group of 5½ inch diameter springs is used, also having a vertical stiffness of about 9600 lbs./in., in a truck with 36 inch wheels. It may be that the vertical spring stiffness per spring group lies in the range of less than 30,000 lbs./in., that it may be in the range of less than 20,000 lbs./in and that it may perhaps be in the range of 4,000 to 12000 lbs./in, and may be about 6000 to 10,000 lbs./in. The twisting of the springs may have a stiffness in the range of 750 to 1200 lbs./in. and a vertical shear stiffness in the range of 3500 to 5500 lbs./in. with an overall sideframe stiffness in the range of 2000 to 3500 lbs./in. 
     In the embodiments of trucks having a fixed bottom spring seat, the truck may have a portion of stiffness, attributable to unequal compression of the springs equivalent to 600 to 1200 lbs./in. of lateral deflection, when the lateral deflection is measured at the bottom of the spring seat on the sideframe. This value may be less than 1000 lbs./in., and may be less than 900 lbs./in. The portion of restoring force attributable to unequal compression of the springs may tend to be greater for a light car as opposed to a fully laden car. 
     Some embodiments, including those that may be termed swing motion trucks, may have one or more features, namely that, in the lateral swinging direction r/R&lt;0.7; 3″&lt;r&lt;30″, or more narrowly, 4″&lt;r&lt;20″; and  5 ″&lt;R&lt;45″, or more narrowly, 8″&lt;R&lt;30″, and in lateral stiffness, 2,000 lbs/in &lt;k pendulum &lt;10,000 lbs/in, or expressed differently, the lateral pendulum stiffness in pounds per inch of lateral deflection at the bottom spring seat where vertical loads are passed into the sideframe, per pound of weight carried by the pendulum, may be in the range of 0.08 and 0.2, or, more narrowly, in the range of 0.1 to 0.16. 
     Friction Surfaces 
     Dynamic response may be quite subtle. It is advantageous to reduce resistance to curving, and self steering may help in this regard. It is advantageous to reduce the tendency for wheel lift to occur. A reduction in stick-slip behavior in the dampers may improve performance in this regard. Employment of dampers having roughly equal upward and downward friction forces may discourage wheel lift. Wheel lift may be sensitive to a reduction in torsional linkage between the sideframes, as when a transom or frame brace is removed. While it may be desirable torsionally to decouple the sideframes it may also be desirable to supplant a physically locked relationship with a relationship that allows the truck to flex in a non-square manner, subject to a bias tending to return the truck to its squared position such as may be obtained by employing the larger resistive moment couple of doubled dampers as compared to single dampers. While use of laterally soft rockers, dampers with reduced stick slip behavior, four-cornered damper arrangements, and self steering may all be helpful in their own right, it appears that they may also be inter-related in a subtle and unexpected manner. Self steering may function better where there is a reduced tendency to stick slip behavior in the dampers. Lateral rocking in the swing motion manner may also function better where the dampers have a reduced tendency to stick slip behavior. Lateral rocking in the swing motion manner may tend to work better where the dampers are mounted in a four cornered arrangement. Counter-intuitively, truck hunting may not worsen significantly when the rigidly locked relationship of a transom or frame brace is replaced by four cornered dampers (apparently making the truck softer, rather than stiffer), and where the dampers are less prone to stick slip behavior. The combined effect of these features may be surprisingly interlinked. 
     In the various truck embodiments described herein, there is a friction damping interface between the bolster and the sideframes. Either the sideframe columns or the damper (or both) may have a low or controlled friction bearing surface, that may include a hardened wear plate, that may be replaceable if worn or broken, or that may include a consumable coating or shoe, or pad. That bearing face of the motion calming, friction damping element may be obtained by treating the surface to yield desired co-efficients of static and dynamic friction whether by application of a surface coating, and insert, a pad, a brake shoe or brake lining, or other treatment. Shoes and linings may be obtained from clutch and brake lining suppliers, of which one is Railway Friction Products. Such a shoe or lining may have a polymer based or composite matrix, loaded with a mixture of metal or other particles of materials to yield a specified friction performance. Shoes and linings may be replaceable, as indicated, for example in U.S. Pat. No. 6,374,749 of Duncan, or U.S. Pat. No. 6,701,850 of McCabe et al, (those documents being incorporated by reference herein). 
     That friction surface may, when employed in combination with the opposed bearing surface, have a co-efficient of static friction, :s, and a co-efficient of dynamic or kinetic friction, :k. The coefficients may vary with environmental conditions. For the purposes of this description, the friction coefficients will be taken as being considered on a dry day condition at  70 F. In one embodiment, when dry, the coefficients of friction may be in the range of 0.15 to 0.45, may be in the narrower range of 0.20 to 0.35, and, in one embodiment, may be about 0.30. In one embodiment that coating, or pad, may, when employed in combination with the opposed bearing surface of the sideframe column, result in coefficients of static and dynamic friction at the friction interface that are within 20%, or, more narrowly, within 10% of each other. In another embodiment, the coefficients of static and dynamic friction are substantially equal. It may be that an elastomeric material may be employed as described in U.S. Pat. Re 31784 or Re 31,988 both of Wiebe, (those documents being incorporated herein by reference) 
     Sloped Wedge Surface 
     Where damper wedges are employed, a generally low friction, or controlled friction pad or coating may also be employed on the sloped surface of the damper that engages the wear plate (if such is employed) of the bolster pocket where there may be a partially sliding, partially rocking dynamic interaction. A controlled friction interface between the slope face of the wedge and the inclined face of the bolster pocket, in which the combination of wear plate and friction member may tend to yield coefficients of friction of known properties, may be used. A polymeric surface, or pad having these friction properties may be used, as may a suitable clutch or brake lining material. In some embodiments those coefficients may be the same, or nearly the same, and may have little or no tendency to exhibit stick-slip behavior, or may have a reduced stick-slip tendency as compared to cast iron on steel. Further, the use of brake linings, or inserts of cast materials having known friction properties may tend to permit the properties to be controlled within a narrower, more predictable and more repeatable range such as may yield a reasonable level of consistency in operation. The coating, or pad, or lining, may be a polymeric element, or an element having a polymeric or composite matrix loaded with suitable friction materials. It may be obtained from a brake or clutch lining manufacturer, or the like. One such firm that may be able to provide such friction materials is Railway Friction Products of 13601 Laurinburg Maxton Ai, Maxton N.C.; another may be Quadrant EPP USA Inc., of 2120 Fairmont Ave., Reading Pa. In one embodiment, the material may be the same as that employed by the Standard Car Truck Company in the “Barber Twin Guard”™ damper wedge with polymer covers. In one embodiment the material may be such that a coating, or pad, may, when employed with the opposed bearing surface of the sideframe column, result in coefficients of static and dynamic friction at the friction interface that are within 20%, or more narrowly, within 10% of each other. In another embodiment, the coefficients of static and dynamic friction are substantially equal. The co-efficient of dynamic friction may be in the range of 0.15 to 0.30, and in one embodiment may be about 0.20. 
     A damper may be provided with a friction specific treatment, whether by coating, pad or lining, on both the vertical friction face and the slope face. The coefficients of friction on the slope face need not be the same as on the friction face, although they may be. In one embodiment it may be that the coefficients of static and dynamic friction on the friction face may be about 0.3, and may be about equal to each other, while the coefficients of static and dynamic friction on the slope face may be about 0.2, and may be about equal to each other. In either case, whether on the vertical bearing face against the sideframe column, or on the sloped face in the bolster pocket, the present inventors consider it to be advantageous to avoid surface pairings that may tend to lead to galling, and stick-slip behavior. 
     Spring Groups 
     The main spring groups may have a variety of spring layouts. Among various double damper embodiments of spring layout are the following: 
     
       
         
           
               
               
               
               
               
               
               
               
               
             
               
                   
               
             
            
               
                 D 1  X 1  D 3   
                 D 1   
                   
                 D 3   
                 D 1   
                 X 1   
                 D 3   
                 D 1  X 1  X 2  X 3  D 3   
                 D 1  X 1  X 2  D 3   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 X 2  X 3  X 4   
                   
                 X 1   
                   
                   
                 X 2   
                 X 4  X 5  X 6  X 7  X 8   
                 D 2  X 3  X 4  D 4   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 D 2  X 5  D 4   
                 X 2   
                   
                 X 3   
                 D 2   
                 X 3   
                 D 4   
                 D 2  X 9  X 10  X 11  D 4   
                   
               
               
                   
                   
                 X 4   
               
               
                   
                 D 2   
                   
                 D 4   
               
            
           
           
               
               
               
               
               
            
               
                 3 × 3 
                 3:2:3 
                 2:3:2 
                 3 × 5 
                 2 × 4 
               
               
                   
               
            
           
         
       
     
     In these groups, D i  represents a damper spring, and X i  represents a non-damper spring. 
     In the context of 100 Ton or 110 Ton trucks, the inventors propose spring and damper combinations lying within 20% (and preferably within 10%) of the following parameter envelopes:
         (a) For a four wedge arrangement with all steel or iron damper surfaces, an envelope having an upper boundary according to k damper =2.41(θ wedge )1.76, and a lower boundary according to k damper =1.21(θ wedge )1.76.   (b) For a four wedge arrangement with all steel or iron damper surfaces, a mid range zone of
 
 k   damper =1.81(θ wedge )1.76(+/−20%).
   (c) For a four wedge arrangement with non-metallic damper surfaces, such as may be similar to brake linings, an envelope having an upper boundary according to k damper =4.84(θ wedge )1.64, and a lower a lower boundary according to k damper =2.42(θ wedge )1.64 where the wedge angle may lie in the range of 30 to 60 degrees.   (d) For a four wedge arrangement with non-metallic damper surfaces, a mid range zone of
 
 k   damper =3.63(θ wedge )1.64(+/−20%).
       

     Where k damper  is the side spring stiffness under each damper in lbs/in/damper
         θ wedge —is the associated primary wedge angle, in degrees       

     θ wedge  may tend to lie in the range of 30 to 60 degrees. In other embodiments θ wedge  may lie in the range of 35-55 degrees, and in still other embodiments may tend to lie in the narrower range of 40 to 50 degrees. 
     In some embodiments the upward and downward damping forces may be not overly dissimilar, and may in some cases tend to be roughly equal. Frictional forces at the dampers may differ depending on whether the damper is being loaded or unloaded. The angle of the wedge, the coefficients of friction, and the springing under the wedges can be varied. A damper is being “loaded” when the bolster is moving downward in the sideframe window, since the spring force is increasing, and hence the force on the damper is increasing. Similarly, a damper is being “unloaded” when the bolster is moving upward toward the top of the sideframe window, since the force in the springs is decreasing. The equations can be written as: 
     While loading: 
     
       
         
           
             
               
                 F 
                 d 
               
               = 
               
                 
                   μ 
                   c 
                 
                 ⁢ 
                 
                   F 
                   s 
                 
                 ⁢ 
                 
                   
                     ( 
                     
                       
                         Cot 
                         ⁡ 
                         
                           ( 
                           Φ 
                           ) 
                         
                       
                       - 
                       
                         μ 
                         s 
                       
                     
                   
                   
                     ( 
                     
                       1 
                       + 
                       
                         
                           ( 
                           
                             
                               μ 
                               s 
                             
                             - 
                             
                               μ 
                               c 
                             
                           
                           ) 
                         
                         ⁢ 
                         
                           Cot 
                           ⁡ 
                           
                             ( 
                             Φ 
                             ) 
                           
                         
                       
                       + 
                       
                         
                           μ 
                           s 
                         
                         ⁢ 
                         
                           μ 
                           c 
                         
                       
                     
                   
                 
               
             
             ⁢ 
             
                 
             
           
         
       
     
     While unloading: 
     
       
         
           
             
               F 
               d 
             
             = 
             
               
                 μ 
                 c 
               
               ⁢ 
               
                 F 
                 s 
               
               ⁢ 
               
                 
                   ( 
                   
                     
                       Cot 
                       ⁡ 
                       
                         ( 
                         Φ 
                         ) 
                       
                     
                     + 
                     
                       μ 
                       s 
                     
                   
                 
                 
                   ( 
                   
                     1 
                     + 
                     
                       
                         ( 
                         
                           
                             μ 
                             c 
                           
                           - 
                           
                             μ 
                             s 
                           
                         
                         ) 
                       
                       ⁢ 
                       
                         Cot 
                         ⁡ 
                         
                           ( 
                           Φ 
                           ) 
                         
                       
                     
                     + 
                     
                       
                         μ 
                         s 
                       
                       ⁢ 
                       
                         μ 
                         c 
                       
                     
                   
                 
               
             
           
         
       
     
     Where:
         F d =friction force on the sideframe column   F s =force in the spring   μ s =coefficient of friction on the angled slope face on the bolster   μ c =the coefficient of friction against the sideframe column   Φ=the included angle between the angled face on the bolster and the friction face bearing against the column       

     For a given angle, a friction load factor, C f  can be determined as C f =F d /F s . This load factor C f  will tend to be different depending on whether the bolster is moving up or down. 
     In some embodiments there may be spring groups that have different vertical spring rates in the empty and fully loaded conditions. To that end springs of different heights may be employed, for example, to yield two or more vertical spring rates for the entire spring group. In this way, the dynamic response in the light car condition may be different from the dynamic response in a fully loaded car, where two spring rates are used. Alternatively, if three (or more) spring rates are used, there may be an intermediate dynamic response in a semi-loaded condition. In one embodiment, each spring group may have a first combination of springs that have a free length of at least a first height, and a second group of springs of which each spring has a free length that is less than a second height, the second height being less than the first height by a distance δ 1 , such that the first group of springs will have a range of compression between the first and second heights in which the spring rate of the group has a first value, namely the sum of the spring rates of the first group of springs, and a second range in which the spring rate of the group is greater, namely that of the first group plus the spring rate of at least one of the springs whose free height is less than the second height. The different spring rate regimes may yield corresponding different damping regimes. 
     For example, in one embodiment a car having a dead sprung weight (i.e., the weight of the car body with no lading, and excluding the unsprung weight below the main springs such as the sideframes and wheelsets), of about 35,000 to about 55,000 lbs (+/−5000 lbs) may have spring groups of which a first portion of the springs have a free height in excess of a first height. The first height may, for example be in the range of about 9¾ to 10¼ inches. When the car sits, unladen, on its trucks, the springs compress to that first height. When the car is operated in the light car condition, that first portion of springs may tend to determine the dynamic response of the car in the vertical bounce, pitch-and-bounce, and side-to-side rocking, and may influence truck hunting behavior. The spring rate in that first regime may be of the order of 12,000 to 22,000 lbs/in., and may be in the range of 15,000 to 20,000 lbs/in. 
     When the car is more heavily laden, as for example when the combination of dead and live sprung weight exceeds a threshold amount, which may correspond to a per car amount in the range of perhaps 60,000 to 100,000 lbs, (that is, 15,000 to 25,000 lbs per spring group for symmetrical loading, at rest) the springs may compress to, or past, a second height. That second height may be in the range of perhaps 8½ to 9¾ inches, for example. At this point, the sprung weight is sufficient to begin to deflect another portion of the springs in the overall spring group, which may be some or all of the remaining springs, and the spring rate constant of the combined group of the now compressed springs in this second regime may tend to be different, and larger than, the spring rate in the first regime. For example, this larger spring rate may be in the range of about 20,000-30,000 lbs/in., and may be intended to provide a dynamic response when the sum of the dead and live loads exceed the regime change threshold amount. This second regime may range from the threshold amount to some greater amount, perhaps tending toward an upper limit, in the case of a 110 Ton truck, of as great as about 130,000 or 135,000 lbs per truck. For a 100 Ton truck this amount may be 115,000 or 120,000 lbs per truck. 
     Table 1 gives a tabulation of a number of spring groups that may be employed in a 100 or 110 Ton truck, in symmetrical 3×3 spring layouts and that include dampers in four-cornered groups. The last entry in Table 1 is a symmetrical 2:3:2 layout of springs. The term “side spring” refers to the spring, or combination of springs, under each of the individually sprung dampers, and the term “main spring” referring to the spring, or combination of springs, of each of the main coil groups: 
     
       
         
           
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Spring Group Combinations 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Group 
                 D7-G1 
                 D7-G2 
                 D7-G3 
                 D7-G4 
                 D7-G5 
                 D5-G1 
               
               
                   
               
               
                 Main Springs 
                 5 * D7-O 
                 5 * D7-O 
                 5 * D7-O 
                 5 * D7-O 
                 5 * D7-O 
                 5 * D5-O 
               
               
                   
                 5 * D6-I 
                 5 * D6-I 
                 5 * D8-I 
                 5 * D8-I 
                 5 * D7-I 
                 5 * D6-I 
               
               
                   
                 5 * D6A 
                 5 * D6A 
                 5 * D8A 
                 5 * D8A 
                 5 * D8A 
                 — 
               
               
                 Side Springs 
                 4 * B353 
                 4 * B353 
                 4 * NSC-1 
                 4 * B353 
                 4 * B353 
                 4 * B432 
               
               
                   
                 — 
                 4 * B354 
                 4 * B354 
                 4 * NSC-2 
                 4 * NSC-2 
                 4 * B433 
               
               
                   
               
               
                 Group 
                 D5-G2 
                 D5-G3 
                 D5-G4 
                 D5-G5 
                 D5-G6 
                 D5-G7 
               
               
                   
               
               
                 Main Springs 
                 5 * D5-O 
                 5 * D5-O 
                 5 * D5-O 
                 5 * D5-O 
                 5 * D5-O 
                 5 * D5-O 
               
               
                   
                 5 * D6-I 
                 5 * D6-I 
                 5 * D8-I 
                 5 * D8-I 
                 5 * D6-I 
                 5 * D6-I 
               
               
                   
                 5 * D6A 
                 — 
                 5 * D8A 
                 5 * D6A 
                 5 * D6A 
                 — 
               
               
                 Side Springs 
                 4 * B432 
                 4 * B353 
                 4 * B353 
                 4 * B353 
                 4 * B353 
                 4 * B353 
               
               
                   
                 4 * B433 
                 4 * B354 
                 4 * B354 
                 4 * B354 
                 4 * B354 
                 4 * B354 
               
               
                   
               
               
                 Group 
                 D5-G8 
                 D5-G9 
                 D5-G10 
                 D5-G11 
                 D5-G12 
                 No. 3 
               
               
                   
               
               
                 Main Springs 
                 5 * D5-O 
                 5 * D5-O 
                 5 * D5-O 
                 5 * D5-O 
                 5 * D5-O 
                 3 * D51-O 
               
               
                   
                 5 * D6-I 
                 5 * D6-I 
                 5 * D8-I 
                 5 * D8-I 
                 5 * D5-I 
                 3 * D61-I 
               
               
                   
                 5 * D6B 
                 5 * D6A 
                 5 * D8A 
                 5 * D8A 
                 5 * D6B 
                 3 * D61A 
               
               
                 Side Springs 
                 4 * NSC-1 
                 4 * NSC-1 
                 4 * NSC-1 
                 4 * NSC-1 
                 4 * B353 
                 4 * B353-O 
               
               
                   
                 4 * NSC-2 
                 4 * B354 
                 4 * B354 
                 4 * NSC-2 
                 4 * NSC-2 
                 4 * B354-I 
               
               
                   
               
            
           
         
       
     
     In this tabulation, the terms NSC-1, NSC-2, D8, D8A and D6B refer to springs of non-standard size. The properties of these springs are given in Table 2a (main springs) and 2b (side springs), along with the properties of the other springs of Table 1. 
     
       
         
           
               
             
               
                 TABLE 2A 
               
             
            
               
                   
               
               
                 Main Spring Parameters 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                 Free 
                   
                 Solid 
                 Free to 
                 Solid 
                   
                 d - Wire 
               
               
                 Main 
                 Height 
                 Rate 
                 Height 
                 Solid 
                 Capacity 
                 Diameter 
                 Diameter 
               
               
                 Springs 
                 (in) 
                 (lbs/in) 
                 (in) 
                 (in) 
                 (lbs) 
                 (in) 
                 (in) 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 D5 Outer 
                 10.2500 
                 2241.6 
                 6.5625 
                 3.6875 
                 8266 
                 5.500 
                 0.9531 
               
               
                 D51 Outer 
                 10.2500 
                 2980.6 
                 6.5625 
                 3.6875 
                 10991 
                 5.500 
                 1.0000 
               
               
                 D5 Inner 
                 10.3125 
                 1121.6 
                 6.5625 
                 3.7500 
                 4206 
                 3.3750 
                 0.6250 
               
               
                 D6 Inner 
                 9.9375 
                 1395.2 
                 6.5625 
                 3.3750 
                 4709 
                 3.4375 
                 0.6563 
               
               
                 D61 Inner 
                 10.1875 
                 1835.9 
                 6.5625 
                 3.6250 
                 6655 
                 3.4375 
                 0.6875 
               
               
                 D6A Inner 
                 9.0000 
                 463.7 
                 5.6875 
                 3.3125 
                 1536 
                 2.0000 
                 0.3750 
               
               
                 Inner 
               
               
                 D61A Inner 
                 10.0000 
                 823.6 
                 6.5625 
                 3.4375 
                 2831 
                 2.0000 
                 0.3750 
               
               
                 Inner 
               
               
                 D7 Outer 
                 10.8125 
                 2033.6 
                 6.5625 
                 4.2500 
                 8643 
                 5.5000 
                 0.9375 
               
               
                 D7 Inner 
                 10.7500 
                 980.8 
                 6.5625 
                 4.1875 
                 4107 
                 3.5000 
                 0.6250 
               
               
                 D6B Inner 
                 9.7500 
                 575.0 
                 6.5625 
                 3.1875 
                 1833 
                 2.0000 
                 0.3940 
               
               
                 Inner 
               
               
                 D8 Inner 
                 9.5500 
                 1395.0 
                 6.5625 
                 2.9875 
                 4168 
                 3.4375 
                 0.6563 
               
               
                 D8A Inner 
                 9.2000 
                 575.0 
                 6.5625 
                 2.6375 
                 1517 
                 2.0000 
                 0.3940 
               
               
                 Inner 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 2b 
               
             
            
               
                   
               
               
                 Side Spring Parameters 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                 Free 
                   
                 Solid 
                 Free to 
                 Solid 
                 Coil 
                 d - Wire 
               
               
                   
                 Height 
                 Rate 
                 Height 
                 Solid 
                 Capacity 
                 Diameter 
                 Diameter 
               
               
                 Side Springs 
                 (in) 
                 (lbs/in) 
                 (in) 
                 (in) 
                 (lbs) 
                 (in) 
                 (in) 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 B353 Outer 
                 11.1875 
                 1358.4 
                 6.5625 
                 4.6250 
                 6283 
                 4.8750 
                 0.8125 
               
               
                 B354 Inner 
                 11.5000 
                 577.6 
                 6.5625 
                 49375 
                 2852 
                 3.1250 
                 0.5313 
               
               
                 B355 Outer 
                 10.7500 
                 1358.8 
                 6.5625 
                 4.1875 
                 5690 
                 4.8750 
                 0.8125 
               
               
                 B356 Inner 
                 10.2500 
                 913.4 
                 6.5625 
                 3.6875 
                 3368 
                 3.1250 
                 0.5625 
               
               
                 B432 Outer 
                 11.0625 
                 1030.4 
                 6.5625 
                 4.5000 
                 4637 
                 3.8750 
                 0.6719 
               
               
                 B433 Inner 
                 11.3750 
                 459.2 
                 6.5625 
                 4.8125 
                 2210 
                 2.4063 
                 0.4375 
               
               
                 49427-1 Outer 
                 11.3125 
                 1359.0 
                 6.5625 
                 4.7500 
                 6455 
               
               
                 49427-2 Inner 
                 10.8125 
                 805.0 
                 6.5625 
                 4.2500 
                 3421 
               
               
                 B358 Outer 
                 10.7500 
                 1546.0 
                 6.5625 
                 4.1875 
                 6474 
                 5.0000 
                 0.8438 
               
               
                 B359 Inner 
                 11.3750 
                 537.5 
                 6.5625 
                 4.8125 
                 2587 
                 3.1875 
                 0.5313 
               
               
                 52310-1 Outer 
                 11.3125 
                 855.0 
                 6.5625 
                 4.7500 
                 4061 
               
               
                 52310-2 Inner 
                 8.7500 
                 2444.0 
                 6.5625 
                 2.1875 
                 5346 
               
               
                 11-1-0562 Outer 
                 12.5625 
                 997.0 
                 6.5625 
                 6.0000 
                 5982 
               
               
                 11-1-0563 Outer 
                 12.6875 
                 480.0 
                 6.5625 
                 6.1250 
                 2940 
               
               
                 NSC-1 Outer 
                 11.1875 
                 952.0 
                 6.5625 
                 4.6250 
                 4403 
                 4.8750 
                 0.7650 
               
               
                 NSC-2 Inner 
                 11.5000 
                 300.0 
                 6.5625 
                 4.9375 
                 1481 
                 3.0350 
                 0.4580 
               
               
                   
               
            
           
         
       
     
     Table 3 provides a listing of truck parameters that may be used in a number of trucks, and for trucks proposed by the present inventors identified as No. 1, No. 2 and No. 3. 
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 Truck Parameters 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                   
                 NACO 
                   
                   
                 ASF Super 
                 ASF 
                   
                   
                   
               
               
                   
                 Swing 
                 Barber 
                 Barber 
                 Service 
                 Motion 
                   
                   
                 No. 3 
               
               
                   
                 Motion 
                 S-2-E 
                 S-2-HD 
                 RideMaster 
                 Control 
                 No. 1 
                 No. 2 
                 2:3:2 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Main 
                 6 * D7-O 
                 7 * D5-O 
                 6 * D5-O 
                 7 * D5-O 
                 7 * D5-O 
                 5 * D5-O 
                 5 * D5-O 
                 3 * D51-O 
               
               
                 Springs 
                 7 * D7-I 
                 7 * D5-I 
                 7 * D6-I 
                 7 * D5-I 
                 5 * D5-I 
                 5 * D8-I 
                 5 * D6-I 
                 3 * D61-I 
               
               
                   
                 4 * D6A 
                   
                 4 * D6A 
                 2 * D6A 
                   
                 5 * D8A 
                 5 * D6A 
                 3 * D61-A 
               
               
                 Side 
                 2 * 49427-1 
                 2 * B353 
                 2 * B353 
                 2 * 5062 
                 2 * 5062 
                 4 * NSC-1 
                 4 * B353 
                 4 * B353 
               
               
                 Springs 
                 2 * 49427-2 
                 2 * B354 
                 2 * B354 
                 2 * 5063 
                 2 * 5063 
                 4 * B354 
                 4 * B354 
                 4 * B354 
               
               
                 k empty   
                 22414 
                 27414 
                 27088 
                 26496 
                 24253 
                 17326 
                 18952 
                 22194 
               
               
                 k loaded   
                 25197 
                 27414 
                 28943 
                 27423 
                 24253 
                 27177 
                 28247 
                 24664 
               
               
                 Solid 
                 103,034 
                 105,572 
                 105,347 
                 107,408 
                 96,735 
                 98,773 
                 107,063 
                 97,970 
               
               
                 H Empty   
                 10.3504 
                 9.9898 
                 9.8558 
                 10.0925 
                 10.0721 
                 9.9523 
                 10.0583 
                 10.0707 
               
               
                 H Loaded   
                 7.9886 
                 7.9562 
                 7.8748 
                 8.0226 
                 7.7734 
                 7.7181 
                 7.9679 
                 7.8033 
               
               
                 k w   
                 4328 
                 3872 
                 3872 
                 2954 
                 2954 
                 6118 
                 7744 
                 7744 
               
               
                 k w /k loaded   
                 17.18 
                 14.12 
                 13.38 
                 10.77 
                 12.18 
                 22.51 
                 27.42 
                 31.40 
               
               
                 Wedge α 
                 45 
                 32 
                 32 
                 37.5 
                 37.5 
                 45 
                 40 
                 45 
               
               
                 F D  (down) 
                 1549 
                 3291 
                 3291 
                 1711 
                 1711 
                 2392 
                 2455 
                 2522 
               
               
                 F D  (up) 
                 1515 
                 1742 
                 1742 
                 1202 
                 1202 
                 2080 
                 2741 
                 2079 
               
               
                 Total F D   
                 3064 
                 5033 
                 5033 
                 2913 
                 2913 
                 4472 
                 5196 
                 4601 
               
               
                   
               
            
           
         
       
     
     In Table 3, the Main Spring entry has the format of the quantity of springs, followed by the type of spring. For example, the ASF Super Service Ride Master, in one embodiment, has 7 springs of the D5 Outer type, 7 springs of the D5 Inner type, nested inside the D5 Outers, and 2 springs of the D6A Inner-Inner type, nested within the D5 Inners of the middle row (i.e., the row along the bolster centerline). It also has 2 side springs of the 5052 Outer type, and 2 springs of the 5063 Inner type nested inside the 5062 Outers. The side springs would be the middle elements of the side rows underneath centrally mounted damper wedges.
         k empty  refers to the overall spring rate of the group in lbs/in for a light (i.e., empty) car.   k loaded  refers to the spring rate of the group in lbs/in., in the fully laded condition.   “Solid” refers to the limit, in lbs, when the springs are compressed to the solid condition   H Empty  refers to the height of the springs in the light car condition   H Loaded  refers to the height of the springs in the at rest fully loaded condition   k w  refers to the overall spring rate of the springs under the dampers.   k w /k loaded  gives the ratio of the spring rate of the springs under the dampers to the total spring rate of the group, in the loaded condition, as a percentage.       

     The wedge angle is the primary angle of the wedge, expressed in degrees. 
     F D  is the friction force on the sideframe column. It is given in the upward and downward directions, with the last row giving the total when the upward and downward amounts are added together. 
     In various embodiments of trucks, such as truck  20  or  22 , the resilient interface between each sideframe and the end of the truck bolster associated therewith may include a four cornered damper arrangement and a 3×3 spring group having one of the spring groupings set forth in Table 1. Those groupings may have wedges having primary angles lying in the range of 30 to 60 degrees, or more narrowly in the range of 35 to 55 degrees, more narrowly still in the range 40 to 50 degrees, or may be chosen from the set of angles of 32, 36, 40 or 45 degrees. The wedges may have steel surfaces, or may have friction modified surfaces, such as non-metallic surfaces. 
     The combination of wedges and side springs may be such as to give a spring rate under the side springs that is 20% or more of the total spring rate of the spring groups. It may be in the range of 20 to 30% of the total spring rate. In some embodiments the combination of wedges and side springs may be such as to give a total friction force for the dampers in the group, for a fully laden car, when the bolster is moving downward, that is less than 3000 lbs. In other embodiments the arithmetic sum of the upward and downward friction forces of the dampers in the group is less than 5500 lbs. 
     In some embodiments in which steel faced dampers are used, the sum of the magnitudes of the upward and downward friction forces may be in the range of 4000 to 5000 lbs. In some embodiments, the magnitude of the friction force when the bolster is moving upward may be in the range of ⅔ to 3/2 of the magnitude of the friction force when the bolster is moving downward. In some embodiments, the ratio of Fd(Up)/Fd (Down) may lie in the range of ¾ to 5/4. In some embodiments the ratio of Fd(Up)/Fd(Down) may lie in the range of ⅘ to 6/5, and in some embodiments the magnitudes may be substantially equal. 
     In some embodiments in which non-metallic friction surfaces are used, the sum of the magnitudes of the upward and downward friction force may be in the range of 4000 to 5500 lbs. In some embodiments, the magnitude of the friction force when the bolster is moving up, Fd(Up), to the magnitude of the friction force when the bolster is moving down, Fd(Down) may be in the range of ¾ to 5/4, may be in the range of 0.85 to 1.15. Further, those wedges may employ a secondary angle, and the secondary angle may be in the range of about 5 to 15 degrees. 
     Nos. 1 and 2 
     The truck embodiment identified as No. 1 may be taken to employ damper wedges in a four-cornered arrangement in which the primary wedge angle is 45 degrees (+/−) and the damper wedges have steel on steel bearing surfaces. In the second instance, the truck embodiment identified as No. 2, may be taken to employ damper wedges in a four-cornered arrangement in which the primary wedge angle is 40 degrees (+/−), and the damper wedges have non-metallic bearing surfaces. No. 2 may employ non-metallic friction surfaces, that may tend not to exhibit stick-slip behavior, for which the resultant static and dynamic friction coefficients are substantially equal. The friction coefficients of the friction face on the sideframe column may be about 0.3. The slope surfaces of the wedges may also work on a non-metallic bearing surface and may also tend not to exhibit stick slip behavior. The coefficients of static and dynamic friction on the slope face may also be substantially equal, and may be about 0.2. Those wedges may have a secondary angle, and that secondary angle may be about 10 degrees. 
     No. 3 
     In some embodiments there may be a 2:3:2 spring group layout. In this layout the damper springs may be located in a four cornered arrangement in which each pair of damper springs is not separated by an intermediate main spring coil, and may sit side-by-side, whether the dampers are cheek-to-cheek or separated by a partition or intervening block. There may be three main spring coils, arranged on the longitudinal centerline of the bolster. The springs may be non-standard springs, and may include outer, inner, and inner-inner springs identified respectively as D51-O, D61-I, and D61-A in Tables 1, 2 and 3 above. The No. 3 layout may include wedges that have a steel-on-steel friction interface in which the kinematic friction co-efficient on the vertical face may be in the range of 0.30 to 0.40, and may be about 0.38, and the kinematic friction co-efficient on the slope face may be in the range of 0.12 to 0.20, and may be about 0.15. The wedge angle may be in the range of 45 to 60 degrees, and may be about 50 to 55 degrees. In the event that 50 (+/−) degree wedges are chosen, the upward and downward friction forces may be about equal (i.e., within about 10% of the mean), and may have a sum in the range of about 4600 to about 4800 lbs, which sum may be about 4700 lbs (+/−50). In the event that 55 degree (+/−) wedges are chosen, the upward and downward friction forces may again be substantially equal (within 10% of the mean), and may have a sum on the range of 3700 to 4100 Lbs, which sum may be about 3850-3900 lbs. 
     Alternatively, in other embodiments employing a 2:3:2 spring layout, non-metallic wedges (i.e., wedges having non-metallic friction linings, pads or coatings, typically mounted to a cast iron or steel damper wedge body) may be employed. Those wedges may have a vertical face to sideframe column co-efficient of kinematic friction in the range of 0.25 to 0.35, and which may be about 0.30. The slope face co-efficient of kinematic friction may be in the range of 0.08 to 0.15, and may be about 0.10. A wedge angle of between about 35 and about 50 degrees may be employed. It may be that the wedge angles lie in the range of about 40 to about 45 degrees. In one embodiment in which the wedge angle is about 40 degrees, the upward and downward kinematic friction forces may have magnitudes that are each within about 20% of their average value, and whose sum may lie in the range of about 5400 to about 5800 lbs, and which may be about 5600 lbs (+/−100). In another embodiment in which the wedge angle is about 45 degrees, the magnitudes of each of the upward and downward forces of kinematic friction may be within 20% of their averaged value, and whose sum may lie in the range of about 440 to about 4800 lbs, and may be about 4600 lbs (+/−100). 
     Combinations and Permutations 
     The present description recites many examples of dampers and bearing adapter arrangements. Not all of the features need be present at one time, and various optional combinations can be made. As such, the features of the embodiments of several of the various figures may be mixed and matched, without departing from the spirit or scope of the invention. For the purpose of avoiding redundant description, it will be understood that the various damper configurations can be used with spring groups of a 2×4, 3×3, 3:2:3, 2:3:2, 3×5 or other arrangement. Similarly, several variations of bearing to pedestal seat adapter interface arrangements have been described and illustrated. There are a large number of possible combinations and permutations of damper arrangements and bearing adapter arrangements. In that light, it may be understood that the various features can be combined, without further multiplication of drawings and description. 
     The various embodiments described herein may employ self-steering apparatus in combination with dampers that may tend to exhibit little or no stick-slip behavior. They may employ a “Pennsy” pad, or other elastomeric pad arrangement, for providing self-steering. Alternatively, they may employ a bi-directional rocking apparatus, which may include a rocker having a bearing surface formed on a compound curve of which several examples have been illustrated and described herein. Further still, the various embodiments described herein may employ a four cornered damper wedge arrangement, which may include bearing surfaces of a non-stick-slip nature, in combination with a self steering apparatus, and in particular a bi-directional rocking self-steering apparatus, such as a compound curved rocker. 
     In the various embodiments of trucks herein, the gibs may be shown mounted to the bolster inboard and outboard of the wear plates on the side frame columns. In some of the embodiments the clearance between the bolster gibs and the side frames may be sufficient to permit a motion allowance of at least ¾″ of lateral travel of the truck bolster relative to the wheels to either side of neutral, advantageously permits greater than 1 inch of travel to either side of neutral, and may permit travel in the range of about 1 or 1⅛″ to about 1⅝ or 1 9/16″ inches to either side of neutral. 
     In one embodiment there may be a combination of a bi-directional compound curvature rocker surface, a four cornered damper arrangement in which the dampers are provided with friction linings that may tend to exhibit little or no stick-slip behavior, and may have a slope face with a relatively low friction bearing surface. However, there are many possible combinations and permutations of the features of the examples shown herein. In general it is thought that a self draining geometry may be preferable over one in which a hollow is formed and for which a drain hole may be required. 
     In each of the trucks shown and described herein, the overall ride quality may depend on the inter-relation of the spring group layout and physical properties, or the damper layout and properties, or both, in combination with the dynamic properties of the bearing adapter to pedestal seat interface assembly. The lateral stiffness of the sideframe acting as a pendulum may be less than the lateral stiffness of the spring group in shear. In rail road cars having 110 ton trucks, one embodiment may employ trucks having vertical spring group stiffnesses in the range of 16,000 lbs/inch to 36,000 lbs/inch in combination with an embodiment of bi-directional bearing adapter to pedestal seat interface assemblies as shown and described herein. In another embodiment, the vertical stiffness of the spring group may be less than 12,000 lbs./in per spring group, with a horizontal shear stiffness of less than 6000 lbs./in. 
     The double damper arrangements shown above can also be varied to include any of the four types of damper installation indicated at page 715 in the 1997 Car and Locomotive Cyclopedia, whose information is incorporated herein by reference, with appropriate structural changes for doubled dampers, with each damper being sprung on an individual spring. That is, while inclined surface bolster pockets and inclined wedges seated on the main springs have been shown and described, the friction blocks could be in a horizontal, spring biased installation in a pocket in the bolster itself, and seated on independent springs rather than the main springs. Alternatively, it is possible to mount friction wedges in the sideframes, in either an upward orientation or a downward orientation. 
     The embodiments of trucks shown and described herein may vary in their suitability for different types of service. Truck performance can vary significantly based on the loading expected, the wheelbase, spring stiffnesses, spring layout, pendulum geometry, damper layout and damper geometry. 
     Various embodiments of the invention have been described in detail. Since changes in and or additions to the above-described best mode may be made without departing from the nature, spirit or scope of the invention, the invention is not to be limited to those details but only by the appended claims.