Abstract:
A railroad hopper car discharge outflow is controlled by closure members, at least one of which is movable. The closure members (or doors) are hingeless, being mounted on four bar linkages, such that the distal edge of the doors sweeps predominantly horizontally while the proximal edge of the door moves predominantly upwardly. The doors move through noncircular arcs, such that the size of the vertically projected door opening is abnormally large compared to the clearance heights of the door during opening and closing. The doors are driven by a transverse drive linkage that is driven by a transversely mounted actuator. The actuator may be mounted in an accommodation in the lee of slope sheets between adjacent hoppers in a mid-span portion of the car. Drive from the actuator is carried to a pair of symmetrically mounted doors through drive train linkages.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to the field of railroad freight cars, and, in particular to railroad freight cars such as may employ bottom unloading gates or doors. 
       BACKGROUND 
       [0002]    There are many kinds of railroad cars for carrying a lading of particulate material, be it sand or gravel aggregate, plastic pellets, grains, ores, potash, coal, or other granular materials. Many of those cars have an upper opening, or accessway of some kind, by which the particulate is loaded, and a lower opening, or accessway, or gate, or door, by which the particulate material exits the car under the influence of gravity. While the inlet opening need not necessarily have a movable gate, the outlet opening requires a governor of some kind that is movable between a closed position for retaining the lading while the lading is being transported, and an open position for releasing the lading at the destination. The terminology “flow through” or “flow through railroad car” or “center flow” car, or the like, may sometimes be used for cars of this nature where lading is introduced at the top, and flows out at the bottom. 
         [0003]    Discharge doors for coal gondola cars or other bottom dumping cars may tend to have certain desirable properties. First, to the extent possible it is usually desirable for the door opening to be large so that unloading may tend to be relatively fast, and for the sides of any unloading chute (e.g. slope sheets) to be relatively steep so that the particulate will tend not to hang up on the slope. Further, to the extent that the door can be large and the slope sheets steep, the interior of the car may tend to have a greater lading volume for a given car length. Further still, any increase in lading achieved will tend to be at a relatively low height relative to Top of Rail (TOR) and so may tend to aid in maintaining a low center of gravity. A low center of gravity tends to yield a better riding car that is less prone to derailment, and perhaps less prone to cause as much wear or damage to tracks. Some cars, such as ballast cars, or cars designed for releasing lading between the rails, may tend to benefit from having discharge doors that are oriented longitudinally, such that the discharge lip of the door runs substantially parallel to the longitudinal centerline of the car, and, in opening, the motion of the door may tend to be predominantly in a direction transverse to the centerline of the car. 
       SUMMARY OF THE INVENTION 
       [0004]    In an aspect of the invention there is a railroad hopper car for operation in a rolling direction along railroad tracks. The railroad hopper car has a first hopper. The said first hopper having a discharge. A pair of first and second doors mounted to govern egress of lading from said discharge. The doors are movable between a closed position for retaining lading within the first hopper and an open position for permitting egress of lading under the influence of gravity. A mechanical transmission is mounted to drive the doors. The first and second doors are longitudinal doors. The mechanical transmission including a splitting member mounted to the railroad hopper car at a fulcrum. A first linkage connected to the splitting member to a first side of the fulcrum, the first linkage is connected to transmit force from the splitting member to the first door. A second linkage connected to the splitting member to a second side of the fulcrum, the second linkage is connected to transmit force from the splitting member to the second door. An actuator mounted to drive the transmission, the actuator is mounted to act transversely relative to the rolling direction. 
         [0005]    In a feature of that aspect of the invention, the first linkage connects to the splitting member at a first distance from the fulcrum, and the splitting member receives drive input from the actuator at a location more distant from the fulcrum than the first distance. In another feature, the first linkage connects to the splitting member at a first distance from the fulcrum, and the second linkage connects to the splitting member at a second distance from the fulcrum, the first and second distances being substantially the same. In another feature, the railroad hopper car having a longitudinal centerline vertical plane, and the fulcrum is mounted substantially at the longitudinal centerline vertical plane. In still another feature, the splitter is a lever, the lever acts in a plane tranverse to the rolling direction of the railroad hopper car, and the splitter receives drive input from the actuator at a connection at a height higher than the fulcrum. In still another feature, the actuator is mounted to the hopper car at a height higher than the fulcrum. In yet another feature, the railroad hopper car has a second hopper mounted longitudinally adjacent the first hopper, and the actuator and the transmission are mounted between the first and second hoppers. In again another feature, the railroad hopper car has first and second side sills, the first hopper is mounted between the first and second side sills, and the actuator is carried at a height higher than the side sills. In a further feature, the transmission is a first transmission, the actuator is a first actuator, and the second hopper has a second pair of first and second doors mounted to govern egress of lading from a discharge of the second hopper. The first transmission and a second transmission are both mounted between the first and second hoppers. The first actuator and a second actuator are both mounted between the first and second hoppers. In another feature the railroad hopper car has stub center sills. 
         [0006]    In another feature, the railroad hopper car has a longitudinal centerline plane. The first door is a moving member of a four bar linkage. The first door has a proximal margin and a distal margin. In the closed position of the door the proximal margin is transversely outboard of the distal margin. A short linkage of the four bar linkage links the proximal margin of the first door to the railroad hopper car. A long linkage of the four bar linkage links the distal margin of the first door to the railroad hopper car. The transmission includes a first crank operable to drive the first door. In operation the short linkage counter-rotates relative to the crank. 
         [0007]    In another feature, the railroad hopper car having a longitudinal vertical centerline plane. The first linkage connects to the splitting member at a first distance from the fulcrum, and the splitting member receives drive input from the actuator at a location more distant from the fulcrum than the first distance. The second linkage connects to the splitting member at a second distance from the fulcrum, the first and second distances is substantially the same. The fulcrum is mounted substantially at the central plane. The splitter is a lever, the lever acts in a transverse plane of the railroad hopper car, and the splitter receives drive input from the actuator at a connection at a height higher than the fulcrum. In another feature, the actuator is mounted to the railroad hopper car at a height higher than the fulcrum. In still another feature, the railroad hopper car has a second hopper mounted longitudinally adjacent the first hopper, and the actuator and the transmission are mounted between the first and second hoppers. The railroad hopper car has first and second side sills, the first hopper is mounted between the first and second side sills, and the actuator is carried at a height higher than the side sills. The transmission is a first transmission, the actuator is a first actuator, the second hopper has a second pair of first and second doors mounted to govern egress of lading from a discharge of the second hopper. The first transmission and a second transmission are both mounted between the first and second hoppers. The first actuator and a second actuator are both mounted between the first and second hoppers. In another feature, the car has stub center sills. 
         [0008]    In another aspect of the invention there is a railroad hopper car for rolling along railroad tracks in a longitudinal direction. The railroad hopper car has a first end section and a second end section. A hopper is mounted between the first and second end sections. The hopper has a bottom discharge. A door is mounted to govern egress of lading from the hopper. The door is movable transverse to the longitudinal direction between a first position for retaining lading in the hopper, and a second position permitting gravity influenced egress of lading from the bottom discharge of the hopper. The door defines a linkage of a four-bar linkage. There is a first door actuator and a second door actuator. The first and second door actuators is jointly operable to move the door. 
         [0009]    In a feature of that aspect of the invention, the door has a first end and a second end, the first end of the door is more proximate to the first end section of the hopper car than is the second end of the door. The first door actuator is mounted to drive the first end of the door, and the second door actuator is mounted to drive the second end of the door. In another feature, the first and second door actuators are pneumatic actuators. In another feature, the hopper has a first slope sheet and a second slope sheet, the first and second slope sheets is downwardly convergent, the first slope sheet is more proximate to the first end section of the hopper car than is the second slope sheet; and the first door actuator is mounted in a lee of the first slope sheet. In still another feature, the door is a full-length hopper door. In a further feature, the bottom discharge of the hopper has a length, L, in the longitudinal direction, and a width, W, cross-wise to the longitudinal direction, and the ratio of L/W is greater than 1.5. In still another feature, the first end section of the railroad hopper car has a stub center sill. In a further feature, the first and second door actuators are mounted transversely whereby the first and second door actuators drive motion that is predominantly cross-wise to the longitudinal direction. In another feature, the first door actuator is mounted to the first end section and the second door actuator is mounted to the second end section. In another feature, the hopper has a first end slope sheet overhanging the first end section, the first end section has a main bolster, and the first door actuator is mounted in a lee of the first end slope sheet and longitudinally inboard of the main bolster. In a further feature, a stub wall extends upwardly of the main bolster to meet the first end slope sheet, a first machinery space is defined between the stub wall and the first end slope sheet, and the first door actuator is mounted in the first machinery space. In a yet further feature, a second machinery space is defined at the second end section and the second door actuator is mounted in the second machinery space. 
         [0010]    These and other aspects and features of the invention may be understood with reference to the description which follows, and with the aid of the illustrations of a number of examples. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0011]    The description is accompanied by a set of illustrative Figures in which: 
           [0012]      FIG. 1   a  is a general arrangement, an isometric view, from above, of an embodiment of a railroad freight car according to an aspect of the invention; 
           [0013]      FIG. 1   b  is a side view of the railroad freight car of  FIG. 1   a;    
           [0014]      FIG. 1   c  is a top view of the railroad freight car of  FIG. 1   a;    
           [0015]      FIG. 1   d  is a bottom view of the railroad freight car of  FIG. 1   a , without showing the trucks, and with the hopper doors in a closed position; 
           [0016]      FIG. 1   e  is a perspective view, from above and to one side and one end, of the door opening mechanism of the railroad freight car of  FIG. 1   a , with forground structure being removed, and with the slope sheets and ridge plate assembly internal gusset plate in cut away; 
           [0017]      FIG. 2   a  is an isometric view, from underneath, of the railroad freight car of  FIG. 1   a;    
           [0018]      FIG. 2   b  is a perspective view, from underneath near the car centerline and to one side, of one hopper of the railroad freight car of  FIG. 1   a , foreground structure being removed to show the relationship of door operation members with the discharge doors in a closed position at the driven end; 
           [0019]      FIG. 2   c  is a side view, with forground structure being removed to show the machinery of the railroad freight car of  FIG. 1   a;    
           [0020]      FIG. 3   a  is a perspective view of the doors of  FIG. 1   c  in a closed position, with all surrounding structure removed; 
           [0021]      FIG. 3   b  is an enlarged view of a single pair of doors of  FIG. 3   a;    
           [0022]      FIG. 3   c  is a view taken on the centerline of the railroad freight car of  FIG. 1   a , with trucks removed, showing the door operating apparatus of  FIG. 3   b  in the fully closed position; 
           [0023]      FIG. 3   d  is the same view as  FIG. 3   c , with the door operating apparatus in the fully open position; 
           [0024]      FIG. 4   a  shows an isometric view of another embodiment of a railroad freight car similar to that of  FIG. 1   a;    
           [0025]      FIG. 4   b  shows side view of the railroad freight car of  FIG. 4   a;    
           [0026]      FIG. 4   c  shows a top view of the railroad freight car of  FIG. 4   a;    
           [0027]      FIG. 4   d  shows an end view of the railroad freight car of  FIG. 4   a;    
           [0028]      FIG. 4   e  shows an isometric view, from underneath, of the railroad freight car of  FIG. 4   a;    
           [0029]      FIG. 4   f  shows an enlarged detail of  FIG. 4   e , with the trucks removed; 
           [0030]      FIG. 4   g  shows a perspective view, from above and to one side and one end, of the doors of  FIG. 4   c , in a closed position and with all surrounding structure removed; 
           [0031]      FIG. 4   h  shows a perspective view, of the doors of  FIG. 4   g , in an open position; 
           [0032]      FIG. 5   a  shows an isometric view of another embodiment of a railroad freight car similar to that of  FIG. 1   a;    
           [0033]      FIG. 5   b  shows an isometric view, from below, of the railroad freight car of  FIG. 5   a;    
           [0034]      FIG. 5   c  shows a side view of the railroad freight car of  FIG. 5   a;    
           [0035]      FIG. 5   d  shows a bottom view of the railroad freight car of  FIG. 5   a , with the trucks removed; 
           [0036]      FIG. 5   e  shows a perspective view, from below and to one side and one end, of the doors of  FIG. 5   d , in a closed position and with all surrounding structure removed; 
           [0037]      FIG. 5   f  shows a perspective view, from above and to one side and one end, of the doors of  FIG. 5   e , in the closed position; and 
           [0038]      FIG. 5   g  shows a perspective view of the doors of  FIG. 5   e , in an open position. 
       
    
    
     DETAILED DESCRIPTION 
       [0039]    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, aspects, or features of the present invention (or inventions, as may be). These examples are provided for the purposes of explanation, and not of limitation, of those principles and of the invention. In the specification, like parts are marked throughout the descriptive text and the drawings with the same respective reference numerals. The drawings are generally to scale, and may be taken as being to scale unless otherwise noted. Unless noted otherwise, the structural members of the car may be taken as being fabricated from steel, most typically mild steel of 50 kpsi or ksi (thousand of pounds per square inch) yield strength. The structure may be of welded construction, most typically, but may alternatively include mechanical fasteners such as Huck™ bolts, rivets, and so on. The structure need not be entirely, or even partially, mild steel, but could include other grades of steel in particular locations, such as the discharge sections, may include consumable wear plates, or plates of greater hardness and wear resistance. In some instances, some or all portions of the primary structure may be made of stainless steel, aluminum, or engineered plastics and composites. Nonetheless, most commonly welded mild steel construction may be assumed as the default condition. 
         [0040]    The terminology used in this specification is thought to be consistent with the customary and ordinary meanings of those terms as they would be understood by a person of ordinary skill in the railroad industry in North America. Following from the decision of the Federal Circuit in Phillips v. AWH Corp., the Applicant expressly excludes all interpretations that are inconsistent with this specification, and, in particular, expressly excludes any interpretation of the claims or the language used in this specification such as may be made in the USPTO, or in any other Patent Office, other than those interpretations for which express support can be demonstrated in this specification or in objective evidence of record in accordance with In re Lee, (for example, in earlier publications by persons not employed by the USPTO or any other Patent Office), demonstrating how the terms are used and understood by persons of ordinary skill in the art, or by way of expert evidence of a person or persons having at least 10 years experience in the railroad industry in North America or in other territories of the former British Empire and Commonwealth. 
         [0041]    In terms of general orientation and directional nomenclature, for railroad cars described herein the longitudinal direction is defined as being coincident with the rolling direction of the railroad car, or railroad car unit, when located on tangent (that is, straight) track. In the case of a railroad car having a center sill, the longitudinal direction or rolling direction is parallel to the center sill, and parallel to the top chords. Unless otherwise noted, vertical, or upward and downward, are terms that use top of rail, TOR, as a datum. In the context of the car as a whole, the term lateral, or laterally outboard, or transverse, or transversely outboard refer to a distance or orientation relative to the longitudinal centerline of the railroad car, or car unit, or of the centerline of a centerplate at a truck center. The terms “longitudinally inboard” and “longitudinally outboard” refer to distances 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. Given that the railroad car described herein may tend to have both longitudinal and transverse axes of symmetry, except as otherwise noted a description of one half of the car may generally also be intended to describe the other half as well, allowing for differences between right hand and left hand parts. Similarly, where male and female parts engage, such as a ball and socket connection, a pin and bushing, a pin and slot, and so on, the male and female engaging part relationship may be interchangeable or reversible, the choice being somewhat arbitrary. Therefore unless otherwise noted, or unless the context requires otherwise, interchangeability or reversibility of mating male and female parts may be assumed as a default without requiring further description of the reverse arrangement. In this description, the abbreviation kspi stands for thousand of pounds per square inch. To the extent that this specification or the accompanying illustrations may refer to standards of the Association of American Railroads (AAR), such as to AAR plate sizes, those references are to be understood as at the earliest date of priority to which this application is entitled. 
         [0042]    Bottom dumping gondola cars may tend to have either longitudinal doors or transverse doors. The term “longitudinal door” means a door that is oriented such that the doors operate on hinges or axes of rotation that are parallel to the direction of travel (i.e., the “longitudinal direction”) of the railroad car generally. An example of a car with longitudinal doors is U.S. Pat. No. 3,633,515 to Shaver et al., issued Jan. 11, 1972. By contrast, “transverse doors” are doors for which the axes of rotation of the hinges or other pivots tend to be predominantly cross-wise to the direction of travel, most often precisely perpendicular to it on a horizontal axis. An example of a car having transverse doors is shown in US Patent Publication No. 2008/0066642 of Forbes et al., published Mar. 20, 2008. 
         [0043]    This specification discusses four bar linkages. One kind of four bar linkage has a reference, or base, member defining the fourth link; a first moving link pivotally connected to the base member; a second moving link pivotally connected to the base member; and a third moving link pivotally connected to the distal ends of the first and second links. A drive input to any one of the first, second, or third links relative to the fixed base will then cause motion of all of the links relative to the reference member. In the discussion that follows, the base link is taken to be the underframe or body structure of the railcar generally, that frame of reference being taken as a datum during opening or closing of the various doors. Of course, the nominally “stationary” datum may itself be rolling, perhaps slowly, along a railroad track as the lading is being disgorged. In the examples given below the actual door panel that blocks the outlet opening of the car is the third link, namely the link that is pivotally connected to the ends of the first and second, links, linkages, or pivot arms, rather than being directly connected to the frame of reference. Most typically some kind of driving mechanism is connected between the base link, (i.e., the rigid structure of the railroad car defining the datum or frame of reference), and one of the moving links, be it the first or second links, or the output member, or third link, of the four bar linkage. Whatever bar of the linkage is driven, the remaining moving members are then slave linkages whose position is dictated uniquely by the input motion and displacement of the driven member relative to the datum. Most often the driven member is one of the first or second links. 
         [0044]    Four bar linkages are often analyzed as if the linkage lies in a plane. Indeed, to the extent that out-of-plane forces are either non-existent or symmetrical and opposite (and therefore balanced), the forces and motions in question can be considered to be wholly or predominantly in a particular plane. In the examples herein, where the doors are “longitudinal doors” as defined above, the action of the forces, and the displacements, whether translational or rotational, may tend to be considered as occurring in a transverse, or cross-wise, vertical plane. 
         [0045]    In the examples of  FIGS. 1   a  to  5   f , the drive force is imparted by an actuator, which may be in the form of a pneumatic piston mounted to act cross-wise to the longitudinal centerline of the car. It acts through a drive shaft or ram or cylinder or piston that is mounted to reciprocate in that plane. The reciprocation is pure linear translation with respect to the actuator body, but since that body is itself pivotally mounted to the structure, the output action may not be linear but may be on a curve in the transverse plane. The drive piston transmits both motion and power through a splitter to drive connecting rods, or links, which impart motion and drive power to the door panels near the distal edges of those panels through their mounts on the distal edge backing-beam or reinforcement members adjacent the door edges. The linkages rotate about their base pivot mounts in parallel y-z planes, the axes of the pivots extending in the x-direction (i.e. longitudinally). 
         [0046]      FIGS. 1   a - 3   d  show respective views of an example of a railroad freight cars indicated as  20 . Although an open-topped hopper car is shown, the illustrations are intended to convey that the features and aspects of the invention (or inventions, as may be) are pertinent to a range of railroad freight cars, rather than a single embodiment. While car  20  may be suitable for a variety of general purpose uses, it may be taken as being symbolic of, and in some ways a generic example of, flow through cars, in which lading is introduced by gravity flow from above, and removed by gravity discharge through gated or valved outlets below. “Flow through”, or “center flow” cars may include open-topped hopper cars, grain cars, plastic pellet cars, potash cars, ore cars, coal gondolas, and so on. In one embodiment car  20  may be a hopper car such as may be used for the carriage of bulk commodities in the form of a granular particulate, be it in the nature of relatively coarse gravel or fine aggregate in the nature of fine gravel or sand or various ores or concentrate or coal. In either case car  20  may be symmetrical about both its longitudinal and transverse, or lateral, centerline axes. Consequently, it will be understood that the car has first and second, left and right hand side beams, bolsters and so on. 
         [0047]    By way of a general overview, car  20  may have a car body  22  that is carried on trucks  24  for rolling operation along railroad tracks. Car  20  may be a single unit car having releasable couplers at each end, as shown, or it may be a multi-unit car having two or more car body units, where the multiple car body units may be connected at substantially permanent articulated connectors, or draw bars. To the extent that car  20  may carry relatively dense materials, draw bar connections in a unit train might be employed. Car body  22 , and the various structural members and fittings described herein may be understood to be typically of metal construction, whether welded or Huck™ bolted, or riveted together, the metal members being most typically steel, stainless steel, or aluminum, as may be appropriate. Some car builders have also used reinforced plastic composites for car elements, and those materials could also be employed where suitable. Car body  22  may have a lading containment vessel or shell  26  such as may include an upstanding peripheral wall structure  28  which may have a pair of opposed first and second end walls  30 ,  32  that extend cross-wise, and a pair of first and second side walls  34 ,  36  that extend lengthwise, the end walls  30 ,  32  and side walls  34 ,  36  co-operating to define a generally rectangular form of peripheral wall structure  28  as seen from above. Wall structure  28  may include top chords  38  running along the top of the walls, and side sills  40  running fore-and-aft (i.e., lengthwise) along lower portions the side sheets  42  of side walls  34 ,  36 . Car  20  may have stub center sills  44  at either end, in which case side walls  34 ,  36  may act as deep beams, and may carry vertical loads to main bolsters  108  that extend laterally from the centerplates. In the case of a single, stand-alone car unit, draft gear and releasable couplers  47  may be mounted at either end of the center sill. Stub center sill  44  has first and second, or left and right hand vertical webs  46 ,  48 , a bottom flange  50 , and a top flange or top cover plate  52 , those four elements being arranged in the conventional manner to define a substantially rectangular hollow tube. Cover plate  52  is carried at a height in the range of something such as 41 to 43 inches above TOR, such that the coupler and draft gear sit in the coupler pocket with a coupler centerline height for a light (i.e., unladen) car with unworn wheels of 34½ inches above TOR, the standard AAR undeflected coupler height. In a center flow, or flow through car, the upper portion of the car may typically include means by which to admit lading under a gravity drop system. Such an intake  54 , or entryway may be a large rectangular opening such as bounded by top chords  38 , or the car may have one or more hatches, whether covered or uncovered. 
         [0048]    Looking at the structure generally, car  20  may have two hoppers, or hopper assemblies, or hopper sections, identified generally and generically as a first hopper  58  and a second hopper  60 . Each hopper has an end slope sheet  62  sloped in the longitudinal direction, and an intermediate slope sheet  64  also sloped in the longitudinal direction. These slope sheets slope upwardly, and away from, a respective first or second hopper discharge section  66 ,  68 . As may be appreciated, the interior or intermediate slope sheets  64  of hoppers  58  and  60  run upwardly and inwardly toward each other, more or less symmetrically, to meet at what is, roughly speaking, a common apex. More precisely, they engage opposite sides of a ridge plate assembly  70  that runs cross-wise between side walls  34 ,  36 . Ridge plate assembly  70  may be made substantially as shown and described herein (or as in US Patent Publication No. 2010/0132587 of Forbes et al.) and lies along the central plane of car  20 . It is not necessary that end slope sheets  62  be inclined at the same angle as intermediate slope sheets  64 . Those slopes may be different. That is, the slope of end slope sheet  62  is substantially shallower than the slope of the intermediate slope sheets  64 . It may be noted that a flat member, or gusset, or plate  72  is mounted beneath ridge plate assembly  70  between the two adjacent intermediate slope sheets  64 , such that a triangular tube is formed that extends across car  20  from side wall  34  to side wall  36 . 
         [0049]    In the embodiment shown in  FIGS. 1   a - 3   d , the lower margins  74 ,  76  of slope sheets  62 ,  64 , respectively, terminate at a level corresponding to the height of side sills  40 , such that margins  74 ,  76  and side sills  40  co-operate to define a generally rectangular opening giving on to hopper discharge sections  66 ,  68  of first hopper  58  and second hopper  60 , respectively. A lateral stiffener in the form of a hollow section beam  78 ,  80  runs cross-wise from side sill to side sill along lower margin  74 ,  76 . Each hopper discharge section  66 ,  68  has a four sided shape that includes first and second side wall members  82 ,  84  that depend downward on an inward decline from side sills  40 , and first and second end wall members  86 ,  88  that run cross-wise across the car, and may extend in substantially vertical planes downwardly from margins  74 ,  76  respectively. The bottom margins of wall members  82 ,  84 ,  86 , and  88  define a generally rectangular opening  90 . Egress of lading from opening  90  is controlled by governors, namely outlet doors or gates, indicated generally as first and second (or left and right hand) doors  100 ,  102 . These doors  100 ,  102  may be symmetrical, such that a description of one serves also to describe the other. 
       Full Length Side Sills 
       [0050]    Side walls  34 ,  36  act as long deep side beams  104 ,  106  that carry the vertical loads of hoppers  58 ,  60 , said walls having upper flanges formed by top chords  38 , bottom flanges formed by side sills  40  and webs defined by side sheets  42 . The vertical loads transferred into the side beams are then carried into stub center sills  44  at the locations of the end stub wall assemblies  130  and main bolsters  108  at the truck centers. Main bolsters  108  each include an upper, or main, flange  110 , a lower flange  112 , and a web  114 . 
         [0051]    Car  20  has a shear plate  128  that extends over (or may define) the top cover of stub center sill  44 , extending across the full width of car  20  from side sill to side sill, such that it underlies side sills  40  and overlies main bolster  108  (or defines the upper flange thereof). Outboard of main bolster  108 , shear plate  128  extends to the end sill of car  20 . Inboard of main bolster  108 , shear plate  128  has triangular portions  126  that taper outwardly to underlie the side sills, leaving an opening  124  beneath end slope sheet  62 . 
       End Wall Defines Deep Lateral Beam 
       [0052]    An end wall, or end wall assembly  130  of car  20  includes a deep, predominantly upwardly extending, transversely running shear web, member, panel, or wall,  132 . Wall  132  has a lower portion  134  and an upper portion  136 . Lower portion  134  lies in a predominantly vertical cross-wise plane. Upper portion  136  is bent relative to lower portion  134 , and extends on an upwardly inclined plane to meet, and mate with, end slope sheet  62 . The lower margin of wall  134  extends upwardly from shear plate  128 . The lower margin of wall  134  is rooted at, or mates with, or is aligned with, upper or main flange  110  of main bolster  108 . In effect, end wall top chord  138 , end slope sheet  62 , beam  80 , wall  132 , and flange  110  co-operate to define a deep beam or deep beam assembly  140  that extends across car  20  from side sill to side sill. The ends of beam  140  are capped by the wings, or shear web panel extensions  142 ,  144  of the side wall shear web sheets  42 . Further, support webs in the nature of elephant ears  146 ,  148  meet center sill cover plate  52  directly above respective center sill webs  46 ,  48 , and are angled on an outwardly splayed slope slightly away from each other, extending upwardly to meet and reinforce end slope sheet  62  and end wall  132 , thus providing load paths by which vertical portions of the shear load from side beams  104 ,  106  and the lading are resolved into stub center sill  44 . 
       Large, Low, Substantially Horizontal Hopper Discharge Opening 
       [0053]    It may also be noted that the lower margins of the stationary structure of the hopper discharge sections are reinforced by hollow structural sections, those on end wall members  86 ,  88  being identified as  156  and those on the sloped, laterally downwardly convergent side wall members  82 ,  84  being identified as  158 . As can be seen in  FIG. 2   b , side sheets  82 ,  84  have members or extension portions identified as ears, or wings  160 , that extend over, and cap, the ends of the hollow section beams  78 ,  80 , and  156  at the top and bottom margins of hopper discharge sections  66 ,  68 . Further, considering the rectangular picture frame defined by the lower margins of the four sheets that define the rectangular discharge opening  90 , several feature may be noted. First, the opening is longer than wide. That is, it has a length, L, in the lengthwise direction of car  20 , and a width, W, in the cross-wise direction. The ratio of L/W may be greater than 3:2 such that each of doors  100 ,  102  may be three times as long as it is wide. In one embodiment the length of the doors may be over 100 inches, and may be about 103 inches, such that two hoppers have a combined opening length of over 200 inches. In this car of  FIGS. 1   a - 3   d  the truck center distance may be less than 500 inches, and in one embodiment is between 385 and 400 inches. Thus the ratio of door length to truck center length is greater than 1:2, and may be in the range of as much as roughly 7:13. The length may be even greater, being roughly 155 inches, such that two doors give a total door length of more than half and in one embodiment as much as roughly ⅝ of the truck center spacing. Nonetheless, the width of the opening is less than 60 inches wide, and in one embodiment is approximately 60 inches wide. Expressed differently, the opening is less than half the overall width of the car, and in one embodiment is roughly 5/11 of the width of the car. Expressed differently, the width is less than the gauge width of the tracks, and, in some embodiments may be in the range of ½ to as much as 1 times the gauge width. Furthermore, the height of the opening above TOR is low. It need not be that the entire opening, or the periphery of the opening defined by lower margins of walls  82 ,  84 ,  86 , and  88 , is planar or lies in a unique horizontal plane. For example, the opening  90  of car  20  is not precisely planar, but is angled slightly upwardly away from the car centerline, the angle in one embodiment being of the order of less than 40 degrees. However, taking the opening  90  as being substantially planar and horizontal, the height of the midpoint of the periphery of the opening  90  on the centerline of car  20  the structure may in one embodiment lie as little as 8 inches above TOR. That is to say, the opening width of the discharge over the mating double doors  100 ,  102  is more than four times, and in one embodiment more than seven times, the clearance height from top of rail to the lip of the opening of the stationary structure, and in one embodiment is more than 8½ times the clearance height (e.g., 70″ width, 8″ clearance). These various ratios are measures of, or proxies for, a physical property of functional significance, namely they are measures of the extent to which a very large, substantially horizontal gate opening permits the car to have a low center of gravity while laded; potentially permits the car to have a larger volume of lading than otherwise (depending on the density of the lading); permits the lading to be discharged more quickly given that the opening is larger and at the same time lower than the center sill, and permits the lading to be discharged with more accuracy and less spread than might otherwise be the case if discharged from a greater height above TOR. 
       Internal Machinery Accommodation Between Hoppers 
       [0054]    In terms of stationary structure, it may be recalled that interior slope sheets  64  of hoppers  58  and  60  meet at ridge plate assembly  70 . As such there is a sheltered machinery space  170  defined between the two hopper discharge sections beneath, or in the lee of, interior slope sheets  64  of adjacent hoppers  58 ,  60 , and, indeed, below plate  72  which forms the bottom closing member of the triangular tube. Although this description is written in the context of a car having two hoppers, the same commentary would apply to a car having any number of hoppers greater than one where the internal slope sheets of two adjacent hoppers meet to form a somewhat protected space. In existing open topped hopper cars the space under the slope sheets is often where so called “elephant ears” or triangular planar shear plates are located, those planar shear plates having one vertex running along the center sill cover plate over one of the center sill webs, a second vertex running upwardly on a diagonal along the back of one of the intermediate slope sheets and a third vertex running upward on a similar diagonal on the back of the other intermediate slope sheet. In the instant car  20 , machinery space  170  is free of such shear plates or elephant ears, or planar web members, such as would otherwise obstruct the space. 
         [0055]    Since machinery space  170  is unobstructed, door drives in the nature of pneumatic cylinders, or pneumatic actuators,  162  and  164  may be located in the accommodation so defined. Location of actuators  162 ,  164  in this accommodation may tend to mean that the actuators are not fit into a tight or difficult machinery space over one of the end sections of the car, competing for space with the brake reservoirs or other equipment. It may also mean that there is better access for servicing and maintenance, and it may mean that the drive train to operate the doors is shorter and more direct than it might otherwise be, because the actuator is immediately beside the mechanism that it is intended to drive, and, in a substantially transverse installation as shown, the actuator is aligned predominantly in the direction of action of force that is desired, making a more compact drive train generally. An extra pressurized air reservoir  172  for operating actuators  162 ,  164  may also be mounted in the machinery space. Air reservoir  172  may have the form or a cylindrical reservoir mounted transversely at the top of machinery space  170  above actuators  162 ,  164 , and may have, for example, a volume of 80 gal. (i.e., twice the typical 40 gal. brake reservoir volume). Since air reservoir  172  is mounted with actuators  162 ,  164  in machinery space  170 , the air pipe distance between them is very short. Actuation may tend to be more rapid without the lag that might otherwise occur with a more distant reservoir. 
       Door Structure 
       [0056]    As noted, the left and right hand doors  100 ,  102  are symmetrical, such that a description of one is equally a description of the other. The main portion of door  100  (or  102 , as may be) is a sheet or pan  174 , which may have a turned-up proximal flange  176  and a turned-down distal lip  178 , as indicated. Door pan  174  may also have turned up lateral edges  180 , the door length (in the x-direction, or longitudinal direction) of car  20  being suited to the opening defined by the lower margins of the hopper discharge section, be it  66  or  68 , the upturned lateral edges seating to either side of the fore-and-aft lower margins of the hopper discharge section to form a seal therealong when the door is closed. Pan  174  is reinforced by a long-direction hollow channel  182 , oriented parallel to the x-direction of the car. Channel  182  is welded toes-in to form a hollow section. Pan sheet  174  is also reinforced by, and carried by, first and second reinforcements  184 ,  186  that run across the outward side thereof from the proximal edge to channel  182 . The distal ends of reinforcements  184 ,  186  extend beyond proximal edge flange  176 , and curl upwardly partially therearound to define mounting lugs  200 ,  202 . Further, spindles, or stub shafts  204  are mounted at the ends of C-channel  182  and define connection interfaces, or connection points for both the door suspension members and the door drive train. 
       Door Linkages 
       [0057]    Doors  100  and  102  are suspended from a set of pivotally movable members or links such as may be identified as door support linkages  210 . Those linkages include a pair of first and second, near end and far end distal door linkages, or arms  212 ,  214 , and a pair of first and second, near and far, proximal, short, door linkages, or arms  216 ,  218 . As may be noted, the distal linkages, or arms,  212 ,  214  are longer than the proximal arms  216 ,  218 . Arms  212 ,  214  have respective first ends pivotally mounted to upper lateral hopper section support member  80  at mounting lugs, or feet,  222 . This is the stationary, or reference or datum end of the link. The other end of arms  212 ,  214  is the pivot mount at the connection interface defined at stub shaft  204 , which may be termed the distant or swinging end. Similarly, the “fixed” or base, or reference, end of short arms  216 ,  218  is mounted to a rotational angular motion and torque transmitting member identified as torque tube  224 , and the “free” or swinging ends of short arms  216 ,  218  pick up on mounting lugs  200 ,  202 . Short arms  216 ,  218  are not rigidly fixed to torque tube  224 , but rather are mounted to rotate independently of it. Torque tube  224  is itself mounted for rotation to a pair of first and second (or near and far) mounting fittings or brackets, or pedestals, or reinforcement members or lugs  226 ,  228 , which may themselves have the form of tapering hollow channel sections mounted toes-in to the outside face of the inwardly inclined side sloping sheets of the hopper discharge sections, those hollow sections also defining discharge section reinforcements extending from one end connected to side sill  40 , and a second, lower end welded to lower edge reinforcement  158 . 
         [0058]    As may be noted, the resultant structure defines a four-bar linkage. The fourth bar, or base, or datum, is the stationary structure whose position is rigidly fixed as part of the car body, namely the stationary structure of discharge section  66 ,  68 , which includes the footings of mounts of the linkages. The long arm pair of arms  212 ,  214  forms the first bar of the four bar linkage. The short arm pair of arms  216 ,  218  forms the second bar of the four bar linkage, and the door panel itself forms the third bar of the four bar linkage. As may be noted, this four-bar linkage is movable between a first position (namely the closed position, shown in  FIG. 3   c ) and a second position (namely the fully open position shown in  FIG. 3   d ). 
         [0059]    In this motion, the long arm link moves through a significantly smaller angular displacement than the short arm link, the long arm moving through roughly 35 to 45 degrees of arc (e.g. approximately 40 degrees), and the short arm link moving through 120 to 150 degrees of arc (e.g. approximately 135 degrees). At the starting position of the motion, both the short and long arms are on angles inward of vertical, such that as the motion begins, both the short and long arms move toward a vertical orientation, and, in so doing, their respective “free” pivot interfaces move in a direction of motion that has both an outward and downward component of motion. That is, dz/dy at both free pivot interfaces is negative; dy being the movement of the interface in the y, or lateral, direction (with the +y direction being defined as a laterially ourboard direction) and dz being defined as the movement of the interface in the z, or vertical, direction (with the +z direction being defined as an upward direction). As will be understood, the +y direction for door  100  will be opposite the +y direction for door  102 . Thus, since there is a −z component of motion, the initial motion serves to “lift” or “unseat” the pan, i.e., move it away from the seat, while the door is also moving predominantly laterally outboard in the +y direction. In this initial stage of motion, the absolute value of dz/dy is also considerably less than 1; that is, the motion is more strongly horizontal than vertical. This horizontal predominance increases as the swinging arms move toward their respective vertical positions. Once past the vertical, the respective pivot connections (or “free” pivot interfaces) begin to move upward while moving laterally outward. The angular displacement of the short arm is more rapid, and its motion is soon predominantly upward (dz/dy&gt;1), and continues so throughout the remainder of the stroke. While this occurs, the longer arm continues its predominantly horizontal motion on a less rapidly changing angular displacement and less strongly positive dz/dy. The effect is that the door panel itself tilts from a very nearly completely horizontal condition to a tipped, inclined position. At the end of the motion, the inside lip of the door may be positioned substantially directly above the rail, or just laterally shy of the inside of the rail bullnose, such that lading exiting the hopper discharge may tend to fall between the rails. 
         [0060]    As will be appreciated, returning the four-bar linkage from the second position (e.g. the fully open position shown in  FIG. 3   d ) to the first position (e.g. the closed position, shown in  FIG. 3   c ) is substantially the inverse of the motion described above. 
       Drive Train 
       [0061]    The motion of the four bar linkage in the opening direction may be commenced by a transmission or drive train  230 , the same drive train being used to close the doors in the other direction once the lading has been discharged. 
         [0062]    The drive train includes drive actuators,  162 ,  164  noted above. Those actuators may be cylindrical rams, such as pneumatic cylinders. One end of each cylinder is pivotally mounted between a base, or reference, or datum or body lug mounted to actuator support beam  234 . In the embodiment illustrated, the piston of each actuator is oriented inboard toward the center of the car, and the back or the actuator is oriented outboard toward side sill  40 . The second end of each actuator is pivotally mounted to an output lever  240  at an output pivot connection  236 . Output lever  240  has a fixed fulcrum or pivot  238  mounted on a pedestal or footing mounted to the face of end wall  86  or  88 , as may be. 
         [0063]    Output lever  240  has two other pivotal connections namely first and second output interface connections,  242  and  244 . The fulcrum, namely fixed pivot  238 , is located mid-way between pivotal connections  242  and  244 . Push rods, or connecting rods, or links  256  and  264  respectively extend from connections  242  and  244  to the crank arms  246 ,  258  of the left and right hand doors. Pivotal connection  244  is located at the distal end of output lever  240 . Pivot connection  236  is located at the opposite end of output lever  240  from connection  244 . Lever  240  is effectively a force and motion splitting device. That is, the input at  236  transmits a total input moment equal to the sum of the output at  242  and  244 . Inasmuch as the geometry is symmetrical, the output transmitted to the cranks  246 ,  258  driving the pairs of left and right hand doors is also matched. In this embodiment the fulcrum, pivot  238 , is located on the longitudinal centerline  122  of the car. The input from each respective actuator is predominantly transverse, and is transmitted to the splitter, i.e., lever  240 , at a height greater than the height of the fulcrum  238 . 
         [0064]    A driving arm or crank arm or crank  246  is pivotally mounted to the near end of torque tube  224 . A connecting member in the nature of a drag link or push rod  256  has a first pivotal connection to output lever  240  at connection  242 , and a second pivotal connection at the distal tip of crank  246 . The drive train includes two further members, the first being a driven arm  248  and the second being a follower or slave link  250 . In normal, or automatic, or power-driven mode, driven arm  248  is connected to crank  246 , such that when crank  246  turns, driven arm  248  turns through the same angle and transmits force and motion to slave link  250 , which, in turn, drives the door, be it  100  or  102 . Motion of connection  236  caused by actuator  162  (or  164 , as may be) will therefore necessarily cause crank  246  to move. As may be understood, in tripping door  100  (or  102 ) to open, member  256  acts in compression as a connecting rod or push rod. In closing door  100 , member  256  acts in tension as a drag link. Follower  250  is pivotally joined at a connection  254  at one end to the distal tip of driven arm  248 , and also pivotally connected to stub shaft  204 . Rotation of driven arm  248  will move the location of connection  254 , which will, in turn cause stub shaft  204  to move, opening or closing door  100  (or  102 ). Follower  250  also has an over-center lock in the form of a finger or abutment  252 . When driven arm  248  is moved to an over center condition with respect to follower  250  (i.e., the pivot axes at  255 ,  257 , and  259  pass through a condition of planar alignment) abutment  252  engages driven arm  248  preventing further motion. As the near end of door  100  (or  102 ) moves, consequent motion occurs in the links of the four bar linkage of the door. Torque tube  224  may tend to force driven arms  248  at both ends of torque tube  224  to move in unison, and thereby to discourage twisting of the door. 
         [0065]    A similar crank arm  258  is mounted to torque tube  224  of door  102 , and functions in the same manner, though of opposite hand. Force and motion are transmitted to crank  258  from second output interface connection pivot  244  of output lever  240  by means of a second transmission member in the nature of a drag link or push rod  264 . Thus motion of the cylinder of actuator  162  (or  164 , as may be) results in laterally outboard motion of drag links  256  and  264  in opposite directions on their respective sides of car  20 , such that doors  100  and  102  operate at the same time in a coordinated, substantially symmetrical manner. It may be noted that output lever  240  is also a force divider in the sense that the single force (and motion) received from actuator  162  (or  164 , as may be) is split and distributed to the right and left hand portions of the drive train. As may be noted, in each case the crank counter-rotates relative to the short, outboard, links  216 ,  218  of the four bar linkage. That is, as crank  246  (or  258 ) turns clockwise, the short linkage  216  (or  218 ) turns counter-clockwise. 
         [0066]    The net result is a mid-car installation that does not compete for space with the brake cylinder or brake reservoir over the truck shear plate. Instead, the mounting is sheltered under the slope sheets above the level of the side sills in a relatively protected location, in which the actuators are also located above the fulcrum of the output divider. The output divider has a single input and two outputs, each of which drives a pushrod connected directly to the respective crank without additional intermediate linkages or connections. 
         [0067]    In the embodiment of  FIGS. 4   a - 4   h , an open top hopper car  320  is substantially similar to open-topped hopper car  20 , and may be taken as having the same structural features unless noted otherwise. It differs therefrom to the extent that hopper car  320  has a hopper body  322  that has a single hopper  324  with full-length left and right hand doors  326 ,  328 . It will be appreciated that car  320  does not have intermediate slope-sheets, and therefore lacks a mid-car machinery space such as machinery space  170 . In this instance there is a machinery space defined longitudinally inboard of stub wall  330  (and therefore longitudinally inboard of main bolster  108 ), in the lee of sloped end sheet  332 . Main shear plate  334  tapers forwardly of main bolster  108  inboard thereof to underlie the side sills longitudinally to the location of stiffening box  336  to which the drive crank  246  is pivotally mounted. The geometry of the four bar linkage, and of doors  326 ,  328  may be taken as being the same as that of doors  100 ,  102 , except that doors  326 ,  328  (and hopper discharge section  338 ) are much longer than doors  100 ,  102  (and either of hopper discharge sections  66 ,  68 ), and that there are four second linkages, or short arms,  216  (or  218 ), rather than two. The four short arms are not joined by a common torque tube, although they could be. Since the door is very long, it may be generally be prone to twisting in torsion about the x-axis. For the purposes of describing doors  326 ,  328 , “very long” means that the length, L, of the doors is greater than 50% of the overall trucks center distance, (i.e., the truck center distance, D, is the distance from the center of the center plate at one main bolster to the center of the center plate at the other main bolster). In the embodiment shown, the ratio of L/D is about 2/3. The ratio of L/W is greater than 3:1. To discourage torsional twisting of doors  326 ,  328 , car  320  has actuators  340 ,  342  mounted at both ends of the doors, such that both ends of each door are driven, rather than relying on one end to follow as a slave linkage. 
         [0068]    The presence of stub sill  344  requires placement of the splitter lever  346  off-center, as illustrated in  FIG. 4   f . That is, fulcrum mount  348  is mounted to a side web of stub sill  344  inboard of the truck center closely adjacent to end wall member  86  (or  88 , as may be). A cross-wise internal shear web  350  is mounted within stub sill  344 , co-planar with mount  348  to provide shear web continuity. A first end of splitter lever  346  extends upwardly of bottom flange  50  of stub sill  344 , and a first connecting rod  352  is pivotally connected from between that first end of lever  346  and crank  246 . A second connecting rod  354  pivot connection is located to the other side of the fulcrum, the first and second connecting rod pivot connections being equidistant from the fulcrum. A second connecting rod extends between that output pivot connection and crank  258 . The actuator input pivot connection is located at the far end of lever  346 . As before, motion of the actuator drives lever  346 , which drives the connecting rods, which turns cranks  246  and  258 , operating doors  326 ,  328  accordingly. 
         [0069]    Other features may also be noted in  FIG. 4   f . For example, the tapering triangular portion  126  of main shear plate  334  is seen extending longitudinally inboard of main bolster  108 , the tapered end underlying side sill  40 . In view of the great length of doors  326  and  328 , the bottom reinforcement of the lower margin of wall member  82  is reinforced by a substantial closed section hollow structural member  360 , which may be in the form of a pressed or roll-formed channel section welded toes-in to the bottom margin of side sheet  42 . Rather than being mounted on a common torque-tube, the short linkage arms  216  may be mounted to angles or gussets mounted to the outside of sheet  42 , and that extend from side sill  40  to member  360 . The large mounting box frame  336  that defines the pivot support for the end short linkage arm  216  and the crank  246  (or  258 ) at the end of the car are shown as  336 , and the mounting box frames for the long, inboard linkage arms  212  are shown as  364 ,  366 . As can be seen, actuator  340  (or  342 ) is mounted above the level of main shear plate  334 , (and, therefore, above the level of the upper flange of the center sill, namely stub sill  344 ) and above the level of the bottom flange of side sill  40 , tucked away in a compact installation in the lee of the end slope sheet, inboard of end stub wall  330  in a relatively protected location in a machinery space in which it does not compete for space with the brakes and brake reservoir. 
         [0070]    The installation of  FIG. 4   f  is shown in the context of a car having a single set of, long, left and right hand doors on a single long discharge section. However, such an end installation could also be used in a car having internal slope sheets, such as car  20 , where it is desired to have a powered-door transmission at both ends of a longitudinal door (or doors), whether to provide faster actuation, to deal with doors having greater inertia, or to avoid twisting e.g., of a door having low torsional stiffness about the x-axis. It may also be noted that the installation of  FIG. 4   f  can be used at a mid-car location in the lee of a pair of internal slope sheets in a car having a straight-through center sill (as opposed to stub center sills), in each case the actuators being mounted above the fulcrum of the splitting lever. 
         [0071]    In the embodiment of  FIGS. 5   a - 5   f , an hopper car  420  is substantially similar to open-topped hopper car  20 , and may be taken as having the same structural features unless noted otherwise. It differs therefrom to the extent that hopper car  420  has a single door  400  or  402  for each hoppers  458  or  460 , respectively, includes one actuator  462  for opening and closing both doors  400 ,  402  simultaneously, and is provided with a roof  404 . To accommodate this configuration, doors  400 ,  402  extend laterally across the entirety of rectangular openings  490 ,  492  of hoppers  458 ,  460 , respectively. Roof  404  need not be included and car  420  may be an open-topped hopper car in some embodiments. 
         [0072]    In the previously described embodiment of hopper car  20 , one actuator  162  (or  164 , as may be) simultaneously opened or closed two doors  100 ,  102  spaced longitudinally from the actuator  162  in the same direction. In the embodiment of car  420 , one actuator  462  simultaneously opens or closes two doors  400 ,  402  spaced longitudinally from the actuator  462  in opposite directions. Resultantly, while the doors  100 ,  102  were predominately offset in a lateral direction from one another in car  20 , the doors  400 ,  401  are predominately offset in a longitudinal direction from one another in car  420 . With the exception of the offset in the longitudinal direction, the motion of the four bar linkage of doors  400 ,  402  is similar to that of linkage of doors  100 ,  102 . 
         [0073]    The motion of the four bar linkage in the opening direction may be commenced by a transmission or drive train  430 , the same drive train being used to close the doors in the other direction once the lading has been discharged. The drive train includes drive actuator  462 , noted above. Actuator  462  may be a cylindrical ram, such as a pneumatic cylinder. One end of the cylinder is pivotally mounted between a base, or reference, or datum, or body lug, mounted to an actuator support beam  434 . In the embodiment illustrated, the piston of the actuator is oriented inboard toward the center of the car, and the back of the actuator is oriented outboard toward side sill  40 . The second end of each actuator is pivotally mounted to an output lever  440  at an output pivot connection  436 . Output lever  440  has a fixed fulcrum or pivot  438  mounted centrally on a support frame  494 . Support frame  494  spans the longitudinal space between hoppers  458 ,  460  is mounted to hollow structural sections  156  on the end walls  86  and  88 . 
         [0074]    Output lever  440  has two other pivotal connections namely first and second output interface connections,  442  and  444 . The fulcrum, namely fixed pivot  438 , is located mid-way between pivotal connections  442  and  444 . Push rods, or connecting rods, or links  456  and  464  respectively extend from connections  442  and  444  to the crank arms  446 ,  448  of the front and back doors  400 ,  402 . Pivotal connection  444  is located at the distal end of output lever  440 . Pivot connection  436  is located at the opposite end of output lever  440  from connection  444 . Lever  440  is effectively a force and motion splitting device. That is, the input at  436  transmits a total input moment equal to the sum of the output at  442  and  444 . Inasmuch as the geometry is symmetrical, the output transmitted to the cranks  446 ,  448  driving the front and back doors is also matched. In this embodiment the fulcrum, pivot  438 , is located on the longitudinal centerline  422  of the car. The input from actuator  462  is predominantly transverse, and is transmitted to the splitter, i.e., lever  440 , at a height greater than the height of the fulcrum  438 . 
         [0075]    A driving arm or crank arm or crank  446  is pivotally mounted to the near end of torque tube  424 . A connecting member in the nature of a drag link or push rod  456  has a first pivotal connection to output lever  440  at connection  442 , and a second pivotal connection at the distal tip of crank  446 . The drive train includes two further members, the first being a driven arm  452  and the second being a follower or slave link  450 . In normal, or automatic, or power-driven mode, driven arm  452  is connected to crank  446 , such that when crank  446  turns, driven arm  452  turns through the same angle and transmits force and motion to slave link  450 , which, in turn, drives the door, be it  400  or  402 . Motion of connection  436  caused by actuator  462  will therefore necessarily cause cranks  446  and  448  to move. As may be understood, in tripping door  400  to open, member  456  acts in compression as a connecting rod or push rod. In closing door  400 , member  456  acts in tension as a drag link. Follower  450  is pivotally joined at a connection  454  at one end to the distal tip of driven arm  452 , and also pivotally connected to stub shaft  406 . Rotation of driven arm  452  will move the location of connection  454 , which will, in turn cause stub shaft  406  to move, opening or closing door  400 . Follower  450  also has an over-center lock in the form of a finger or abutment  466 . When driven arm  452  is moved to an over center condition with respect to follower  450  (i.e., the pivot axes at  455 ,  457 , and  459  pass through a condition of planar alignment) abutment  466  engages driven arm  452  preventing further motion. As the near end of door  400  moves, consequent motion occurs in the links of the four bar linkage of the door. Torque tube  424  may tend to force driven arms  452  at both ends of torque tube  424  to move in unison, and thereby to discourage twisting of the door. 
         [0076]    A similar crank arm  448  is mounted to torque tube  424  of door  402 , and functions in the same manner, though of opposite hand. Force and motion are transmitted to crank  448  from second output interface connection pivot  444  of output lever  440  by means of a second transmission member in the nature of a drag link or push rod  464 . Thus motion of the cylinder of actuator  462  results in laterally outboard motion of drag links  456  and  464  in opposite directions on their respective sides of car  420 , such that doors  400  and  402  operate at the same time in a coordinated, substantially symmetrical manner. It may be noted that output lever  440  is also a force divider in the sense that the single force (and motion) received from actuator  462  is split and distributed to the right and left hand portions of the drive train. As may be noted, in each case the crank counter-rotates relative to the short, outboard, links  416 ,  418  of the four bar linkage. That is, as crank  446  (or  448 ) turns clockwise, the short linkage  416  (or  418 ) turns counter-clockwise. 
         [0077]    The net result is a mid-car installation that does not compete for space with the brake cylinder or brake reservoir over the truck shear plate. Instead, the mounting is sheltered under the slope sheets above the level of the side sills in a relatively protected location, in which the actuators are also located above the fulcrum of the output divider. The output divider has a single input and two outputs, each of which drives a pushrod connected directly to the respective crank without additional intermediate linkages or connections. 
         [0078]    The doors in the various cars may be operated by a control unit that is connected to operate the valves of the system causing the actuators to advance or retract, as may be. Such a control unit may be used on any of cars  20 ,  320 , or  420 . In this instance a control box, or controller is indicated as  480 . Controller  480  may be mounted in the lee of the slope sheets closely adjacent to whichever actuator it is intended to control, such that the various air pipes may be kept short, such as may reduce lag time in reaction to commands. Controller  480  may have an external actuation interface member  482 , that is, an member defining an interface such that the controller may be operated externally to car  20 ,  320 , or  420 . In the examples shown, external actuation interface member  482  may have the form of a magnetic field sensor  484  such as may be mounted on an outside portion of the car. In the examples of  FIGS. 1   a , and  2   a , magnetic sensor  484  is mounted to the side of the car above side sill  40  at a mid-car, or mid-span location immediately adjacent to controller  480 . When exposed to a magnetic signal of a first polarity, the doors open; when exposed to signals of the opposite polarity, the doors close. An unloading facility may have magnetic signal emitting devices at track-side such that as the car rolls past, the signals are received and the doors open and close accordingly. It may be that the signal sensor may also need a coded recognition signal to prevent inadvertent or unauthorised opening and closing of the doors. 
         [0079]    Other features may also be noted in  FIG. 5   f . For example, short linkages  416 ,  418  include slots  470  at the end of the linkages distal from the connection between the linkages  416 ,  418  and the torque tubes  424 . 
         [0080]    This application is filed contemporaneously with another application entitled Railroad Hopper Car and Door Mechanism Therefor, the specification and drawings thereof being incorporated herein by reference in their entirety, the same as if the specification thereof had been included at this point in this specification, and the same as if the drawings thereof had been added to follow the drawings hereof, with item numbers in the text and the annotations on the drawings amended accordingly. 
         [0081]    Various embodiments have been described in detail. Since changes in and or additions to the above-described examples 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 a purposive interpretation of the claims as required by law.