Abstract:
A railroad car wheelset has an axle with one wheel ( 14 A) rigidly attached. This wheel is permitted to rotate by means of journal bearings either on the extreme ends of the axle or inboard of each wheel location. At the other wheel, the axle has smooth surface and a self-lubricating bearing ( 54 ) is provided as a part of a hub on the axle. The hub is integral with the axle or press fit thereon. The axle has a boss for preventing the independently rotating wheel from migrating laterally out of proper alignment. A self-lubricating thrust bearing ( 32 ) is located between this boss and the side of the wheel to eliminate any possible galling between the two moving surfaces.

Description:
This is a continuation in part of Ser. No. 09/021,604 filed Feb. 10, 1998 now U.S. Pat. No. 6,007,126 which is a continuation of Ser. No. 09/004,362 filed Jan. 8, 1998 now U.S. Pat. No. 6,048,015. 
    
    
     BACKGROUND OF THE INVENTION 
     Wheelsets for railroad cars are usually comprised of an axle and two wheels. The wheels are pressed on to the axle shaft and are rigidly mounted so that both wheels turn exactly the same degree of rotation during operation. The wheelset assembly may be supported by journal bearings outboard of each wheel or the bearings may be located inboard of the wheels. The rigid assembly of the wheels on the axle and the lack of independent rotation of the wheels is the cause of slippage on the rail when the wheelset operates in curved sections of track. This slippage causes wear on the wheel treads and rails and is a prime cause of corrective maintenance on both the wheels and the track. 
     Efforts have been made to overcome the problems associated with the rigid assembly of conventional wheelsets by placing bearings between the axle and the wheel on at least one end of the axle to permit differential speeds of rotation of the wheels at opposite ends of the axle. In such cases, a hub is located on at least one end of the axle and a wheel is mounted on the hub or on the axle and its rotation with respect to the axle is facilitated by a bearing assembly. As discussed hereafter, electrical continuity from the two rails through the wheels and the axle is necessary for operation of signal devices or the like. This electrical continuity was established with the conventional railroad wheelsets wherein the wheels were rigidly fixed through opposite ends of the axle. However, with the advent of one of the wheels being mounted on the axle by means of a bearing assembly, the electrical continuity between the wheels was less than perfect. With the advent of non-metallic bearings, the electrical continuity was not possible. 
     A typical signal device for a road crossing, for example which utilizes a crossing arm, flashing lights, and the like, derives electrical energy from any conventional source. A low voltage is imposed on a given dedicated length of rail on opposite sides of the signal, with the opposite rail being electrically connected to the signal whereupon the signal circuit is closed when the wheel assembly of a train initially moves onto the dedicated length of rail. The circuit is completed between the opposite rails through the wheels and axle of the train&#39;s wheel assemblies which allow the flow of energy therethrough to electrically connect the opposite rails. 
     Even when a differential action wheelset is used, an adverse situation may arise wherein, upon beginning motion, one of the independent wheels moves in one direction and the other wheel on the axle moves in the opposite direction in a pivoting effect. That is because when an axle is provided with one or more independently rotatable wheels, it is possible for the axle to rotate about its vertical centerline if one of the wheels rotates in one direction and the other wheel rotates in the opposite direction. If the axle with the independently rotatable wheels is mounted in a short wheelbase two-axle truck, it may be possible for the two wheels on one side of the truck to move in one direction, while the two wheels on the other side of the truck rotate in the opposite direction. This action may result in derailing the truck and will be more pronounced and prevalent in a short wheelbase two-axle truck than in a long wheelbase two-axle truck. 
     Field testing by the American Association of Railroads (described in ASME Paper No. 7-5, dated Sep. 12-15, 1988) indicates that in certain situations it is desirable to have the wheelset in the leading axle position of a multi-axle truck be equipped with non-independent wheel rotation, and the wheelset in the trailing axle position equipped with independently rotating wheels. The problem in such an arrangement is that the leading axle wheelset when the railroad car is operating in one direction is the trailing axle wheelset when the railroad car operates in the opposite direction. 
     It is, therefore, a principal object of this invention to provide a railroad car wheelset with independently rotating wheels in which the differential action is made inoperable upon stopping and at lower speeds, and when the differential action is automatically resumed when the wheel rotation reaches a predetermined operational speed. 
     A further object of this invention to provide a railroad wheelset with independent rotation of wheels with respect to each other which will consistently retain the electrical continuity between the opposite wheels and the rails upon which they are supported. 
     A still further object of this invention is to provide a wheelset with independent rotation of the wheels with respect to each other which can be used in existing truck designs without modification to the truck structures or the braking system. 
     A still further object of this invention is to provide a railroad wheelset which requires no additional maintenance than conventional rigid wheelsets after installation and during service. 
     A still further object of this invention is to provide a railroad wheelset with independently rotating wheels in which the differential action is made available with no decrease in safety or reliability. 
     A still further object of this invention is to provide a railroad car wheelset with independent wheel rotation which can be economically manufactured and applied to railroad cars of all types. 
     A still further object of this invention is to provide a railroad car wheelset in which both wheels can rotate independently in one direction on the axle, and be locked against rotation in the other direction. 
     A still further object of this invention is to provide the alternate capability of operating a wheelset either as a fixed-wheel wheelset in one direction and as an independently rotatable wheel wheelset in the opposite direction. 
     A still further object of this invention is to permit the alternate capability to be achieved using a minimum of special parts and a maximum of common parts. 
     These and other objects will be apparent to those skilled in the art. 
     SUMMARY OF THE INVENTION 
     The railroad car wheelset of the present invention includes an axle with one wheel rigidly attached as in conventional railroad practice. This wheel is permitted to rotate by means of journal bearings either on the extreme ends of the axle or inboard of each wheel location. At the location of the other wheel, the axle is provided with a smooth surface and a self-lubricating bearing is provided. The axle shaft is provided with a boss or other means of preventing the independently rotating wheel from migrating laterally out of proper alignment. A self-lubricating thrust bearing is located between this boss and the side of the wheel to eliminate any possible galling between the two moving surfaces. A removable retainer plate is located on the other side of the independently rotating wheel to prevent the wheel from moving laterally in that direction. Adjacent the removable retainer plate is an electrical contactor which can conduct an electrical current from the wheel to the axle shaft, to permit the wheelset to properly operate railway signals or other systems dependent on electrical continuity. In lieu of the self-lubricated bearings, the bearings can be comprised of a lubricant coating permanently bonded to the bearing surface of the hub adjacent the independently rotatable wheel. 
     An axle with two wheels in which one wheel may rotate independently of the other may be pivoted about its vertical centerline in the event one of the wheels rotates in one direction and the other wheels rotate in the opposite direction. The railroad car wheelset of the present invention may include a means of locking the independently rotatable wheel to the axle rigidly when the rotation of the wheel ceases, or when the wheel is rotated slowly. This locking means automatically releases when the wheel and axle reach a predetermined speed of rotation, at which time the differential action of the independently rotating wheel is again permitted. 
     An alternate form of the present invention is provided for situations in which one of the wheelsets in a truck is desired to be of the fixed-wheel type in one direction and also is desired to function as an independently rotatable wheel wheelset in the opposite direction. The railroad car wheelset of the present invention includes a means of locking the independently rotatable wheel to the axle rigidly when the rotation of the wheel is in one direction, and automatically unlocking the independently rotatable wheel from the axle when the rotation of the wheel is in the opposite direction. The proper arrangement of these wheelsets in the truck frame permits the leading axle to automatically operate as a fixed-wheel wheelset and the trailing axle to operate as an independently rotatable wheel wheelset regardless of which direction the railcar is moving. 
     Thus, the independently rotatable wheel is locked to the axle automatically in one direction and permits the independent rotation of the wheel automatically when the rotation is in the opposite direction. By arranging the wheelsets 180° from each other in the truck frame (as shown in FIG.  14 ), the trailing axle is always equipped with independently rotating wheels and the leading axle is always functioning as a conventional axle with two fixed and non-independently rotating wheels. 
     The hubs are either integral with the axle, or pressed on the axle. An alternate form of the invention is provided in which both wheels can rotate independently on the axle in one direction, and be restrained from rotating independently in the opposite direction. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an elevational view of a conventional prior art railroad wheelset; 
     FIG. 2 is an elevational view of the preferred embodiment of the railway wheelset; 
     FIG. 3 is an exploded view of the components within the line  4 — 4  of FIG. 2; 
     FIG. 4 is an enlarged scale view of the components contained within the line  4 — 4  of FIG. 2; 
     FIG. 5 is a transverse sectional view of the structure of FIG. 4; 
     FIG. 6 is an elevational view of the structure of FIG. 4 as viewed from the left-hand side of FIG. 4; 
     FIG. 7 is an elevational view similar to that of FIG. 2 but shows the preferred embodiment of this invention; 
     FIG. 8 is a large scale partial elevational view taken on line  8 — 8  of FIG. 7; 
     FIG. 9 is an elevational view looking at the inside of the independently rotatable wheel when it is stopped or operating at low speed, showing the upper rotatable latches engaging the toothed integral axle retainer hub; 
     FIG. 10 is an elevational view looking at the inside of the independently rotatable wheel when it is rotating above a predetermined speed, showing that the rotatable latches have moved outwardly and that none of the rotatable latches engage the toothed integral axle retainer, and that the wheel is again able to rotate independently of the axle; 
     FIG. 11 is a sectional view taken on line  11 — 11  of FIG. 9; 
     FIG. 12 is an elevational view looking at the inside of the alternate form of the independently rotatable wheel when it is operating in a clockwise manner; 
     FIG. 13 is an elevational view looking at the inside of the alternate form of the independently rotatable wheel when it is operating in a counter-clockwise manner; and 
     FIG. 14 is a plan view showing the positions of the locking devices of FIGS. 12 and 13 of the independently rotatable wheels as the axles are mounted in a truck frame; 
     FIG. 14A shows a similar arrangement showing linking devices on all four wheels; 
     FIGS. 15A and 15B are partial elevational views of inner and outer clutch plates of an alternate form of the invention; 
     FIG. 15C is a partial sectional view of the clutch plates when they are in a free-wheeling mode typical in the prior art; 
     FIG. 15D is a view similar to FIG. 16 but shows the clutch plates in a driving mode; 
     FIG. 15E is a sectional view of the clutch plates mounted on a hub; 
     FIG. 16 is a sectional view through an alternate press-on hub that is pressed on the axle; 
     FIG. 17 is an end elevational view of the hub shown in FIG. 18; 
     FIGS. 18 and 19 are elevated views similar to FIGS. 12 and 13 but show an alternate form of the invention using a bolt on latch pin mounting plate and a two piece ratchet gear; and 
     FIG. 20 is a sectional view taken on lines  20 — 20  of FIG.  18 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The conventional prior art wheelset  10  is shown in FIG.  1  and is comprised of the horizontal axle  12  with wheels  14 A and  14 B adjacent its opposite ends. The wheels  14 A and  14 B are each rigidly secured to axle  12  by being pressed on the axle up against bosses  18 , respectively. 
     A preferred differential action railroad car wheelset is shown in FIGS. 2,  3 ,  4 ,  5  and  6 . With reference to FIG. 2, the right-hand wheel  14 B is affixed to the axle  12  in the same manner that wheel  14 B was secured to the axle  12  in FIG.  1 . However, at the other end of axle  12  in FIG. 2, a hub  20  is integral with the axle  12 . Hub  20  has an annular flange  22  of increased diameter. With reference to FIG. 3, hub  20  has a cylindrical bearing surface  24  and a vertical bearing surface  26  adjacent thereto. A vertical circular face  28  on hub  20  has a plurality of threaded apertures  30 . 
     A cylindrical flat planar thrust bearing  32  is mounted on bearing surface  24  and when assembled, bears against bearing surface  26 . A cylindrical sleeve bearing  34  is then mounted on bearing surface  24  adjacent the thrust bearing  32 . In assembly, the wheel  14 A which has a large diameter center bore  36  is slidably mounted on the sleeve bearing  34  (FIG.  5 ). The center bore  36  of wheel  14 A has an annular groove  38  on the outboard side thereof. A circular metal conductor plate  40  with the center opening  42  and a plurality of apertures  44  (equal in number and size to apertures  30  in face  38  of hub  20 ) is mounted within annular groove  38 . A retainer plate  46  (FIGS. 3 and 5) is also mounted in annular groove  38 . Retainer plate  46  has a center opening  48  and a plurality of apertures  50 . Conventional threaded bolts  52  extend through the registering apertures  50  (in retainer plate  46 );  44  (in conductor plate  40 ); and  30  (in hub  20 ). 
     It should be noted (FIG. 4) that a space  54  exists between the bearing surface  24  of hub  20  and the center opening or bore  36  in wheel  14 A. This space is normally occupied by sleeve bearing  34 . However, in an modified form of the invention, the space  54  can be filled with a lubricating coating (not shown), in lieu of the sleeve bearing  34 . Wheel bore  36  can be adjusted in diameter as required. 
     There are available in the industry synergistic coatings (e.g., Hi-T-Lube®) which become an integral part of the top layer of a base metal rather than merely a surface cover. This lubricating coating has a hard interface metal layer adjacent the base metal; a semi-soft, compressible metal layer adjacent the base metal; a semi-soft, compressible metal layer adjacent the hard interface layer; a hard, thin oxide layer adjacent the compressible layer; and an outer malleable, dry lubricant layer on the outer surface of the thin oxide layer. This lubricating layer can resist wear of the base metal by up to 15 times under cryogenic conditions. This and other lubricating coatings in the industry in environments from room temperature up to 1000 degrees Fahrenheit can withstand high applied loads at relatively high speeds and frequent reversal in direction. Under such conditions, these products performed effectively for long periods of time where other lubricants and combinations of materials failed in a relatively short period of time. The thickness of the coating (and the radial height of space  54 ) can be in the order of 0.0003 inches-0.001 inches in thickness and has a coefficient of friction in the range of 0.03 and can withstand high compression loads in excess of 150,000 psi. Hardness of available material is up to an equivalent of Rc 55.-R c  85. These materials are not, per se, a part of this invention and have not been previously used in the application of bearings for railway wheelsets but the present invention makes provision for this technology. 
     It should be understood that the space  54  normally occupied by a bearing sleeve  34  could be occupied by the lubricating coating described heretofore instead of the sleeve bearing  34 . 
     It is therefore seen that the wheelsets of this invention can be easily assembled and can easily create a wheelset with a single rigid wheel at one end of the axle and an independently rotatable wheel at the other end of the axle. The electrical continuity through the wheelset is guaranteed by the presence of conductor plate  40  which can maintain this electrical continuity without having to pass through the wheel bearings themselves. With reference to FIG. 2, the electrical continuity between the rails upon which wheels  14 A and  14 B are mounted is completed from the rail under wheel  14 B through wheel  14 B and thence through axle  12 , through conductor plate  40 , and into wheel  14 A to the opposite rail. 
     DESCRIPTION OF ALTERNATE FORMS OF THE INVENTION 
     As previously indicated, when the axle is provided with one or more independently rotatable wheels, it is possible for the axle to rotate about its vertical centerline if one of the wheels rotates in one direction and the other wheel rotates in the opposite direction. If the axle with the independently rotatable wheels is mounted in a short wheelbase two-axle truck, it may be possible for the two wheels on one side of the truck to move in one direction, while the two wheels on the other side of the truck rotate in the opposite direction. This action may result in derailing the truck and will be more pronounced and prevalent in a short wheelbase two-axle truck than in a long wheelbase two-axle truck. 
     To prevent the independently rotatable wheel from rotating in the opposite direction from the other wheel, an automatic locking means is provided to prevent the rotation of the independently rotatable wheel when stopped or when operating at low speeds. When the rotation of the locked independently rotatable wheel reaches a predetermined rotational speed, the locking means automatically releases and the differential action can again be utilized. 
     With references to FIGS. 7-11, an independently rotatable wheel  14 C is shown. The axle retainer hub  56  has been modified to provide engagement teeth  58  for releasable engagement with a plurality of pivoting latches  60  which are equipped with self-lubricating bearings  62  mounted on pivot pins  64 . Each latch  60  has engagement teeth  61  adapted to nest at times between teeth  58  on hub  56 . Each pivot pin  64  is equipped with self-lubricating thrust bearing latch retainers  66  which are in turn secured by means of stainless steel snap rings  68  or equivalent. Each pivot pin  64  is securely inserted into a latch boss  70  made integral with the wheel. The latch boss may be deleted when a separate latch pin mounting plate is used, attached to the wheel as shown in FIGS. 18 and 19, as discussed hereafter. Also integral with and offset from the wheel are a plurality of latch stops  72  which restrict the travel of the pivoting latches  60  from excessive outward travel. 
     FIG. 9 shows the configuration of the rotatable latch  60  when acted upon by gravity when the independently rotatable wheel  14 C is rotating slowly or is at rest in a motionless state. FIG. 10 shows the position of the rotatable latches  60  when acted upon by centrifugal force and restrained from further outward motion by integral latch stops  72 . 
     The foregoing structure of FIGS. 7-11 provide means for locking the independently rotatable wheel to the axle rigidly when the rotation of the wheel ceases, or when the wheel is rotated slowly. This locking means automatically releases when the wheel and axle reach a predetermined speed of rotation, at which time the differential action of the independently rotating wheel is again permitted. A typical speed at which this takes place is 5-10 mph or a wheel speed of 50-100 rpms. This is accomplished by the axle retainer hub  56  being provided with teeth  58  for releasable engagement by the rotatable latches  60  pivotally mounted on pivot pins  64 , said rotatable latches engaging the toothed retainer hub  36  by gravitational action when the wheel  14 C is not rotating or rotating at slow speed, and the rotatable latches  60  disengaging teeth  58  due to centrifugal force when the wheel  14 C rotates beyond a predetermined speed. 
     An alternate embodiment of the foregoing invention is shown in FIGS. 12,  13  and  14 . With reference to FIGS. 12,  13  and  14 , the wheel  14 C is capable of independent rotation with respect to axle  12 , as previously described. The axle retainer hub  56 A has been modified to provide engagement teeth  58 A, each with a near-radial bearing surface on the clockwise side  59 , and a sloping surface  59 A on the counter-clockwise side. These engagement teeth  58 A are for releaseable engagement with a plurality of pivoting double-arm latches  60 A which are equipped with self-lubricating bearings  62  mounted on pivot pins  64 . (FIG.  8 ). Each latch has an engagement tooth  61 A adapted to nest at times between teeth  58 A on hub  56 A. As with the structure of FIGS. 9-11, each pivot pin  64  is equipped with self-lubricating thrust bearing latch retainers  66  which are in turn secured by means of stainless steel snap rings  68  or equivalent. Each pivot pin  64  is securely inserted into a latch boss  70  made integral with the wheel. Also integral with and offset from the wheel are a plurality of latch stops  72  which restrict the travel of the pivoting latches  60 A from excessive outward travel. Centrifugal force acting on the weighted end  60 B of the pivoting latches  60 A tends to keep the engagement teeth  61 A of these latches in proper position with respect to the axle retainer hub engagement teeth  58 A, when the wheel rotates, or, when the wheel is stopped or operating at very slow speeds, gravitational force acting on the weighted ends  60 B of the double-arm latches  60 A tends to keep the engagement teeth  61 A of these latches in engaged position. In FIG. 12, it is to be noted that the arrow indicating direction of rotation relates to the rotation of the axle  12  and axle retainer hub  56 A with respect to possible rotation of the independently rotatable wheel  14 C and not to the rotation of the wheel with respect to a non-rotating axle. The wheel  14 C cannot rotate in a counter-clockwise manner with respect to the axle as shown in FIG.  12 . 
     FIG. 13 shows the above components in play when rotation is in the opposite direction. Although the centrifugal and gravitational forces tend to keep the engagement teeth  61 A of the pivoting double-arm latches  56 A in proper position for engagement with the teeth  58 A of the toothed axle retainer hub  56 A, the sloping surface  59 A of the teeth of the axle retainer hub prevent the proper engagement of the teeth and permit the wheel to rotate independently in the clockwise direction. Again, it is to be noted that the rotation depicted in FIG. 13 relates to the rotation of axle  12  and the axle retainer hub  56 A with respect to possible rotation of the independently rotatable wheel  14 C, and not to the rotation of the wheel with respect to a non-rotating axle. The wheel  14 C can rotate in a clockwise manner with respect to the axle as shown in FIG.  13 . Since the differential rotation of one wheel with respect to the other wheel of a wheelset is not expected to ever exceed 15 RPM, wear to the teeth  61 A of the pivoting double-arm latches  60 A or to the toothed axle retainer hub is expected to be minimal. 
     FIG. 14 is a diagram showing placement of the independently rotatable wheels and locking mechanisms for the wheelsets in a railroad car truck T. FIG. 14A shows how both wheels on the axles can rotate independently and be locked in reverse direction. 
     The foregoing structure of FIGS. 12-14 provide means for automatically locking the independently rotatable wheel  14 C to the axle  12  rigidly in one direction, and automatically disengaging the independently rotatable wheel from the axle when rotation is in the opposite direction. This is accomplished by the axle retainer hub  56 A being provided with teeth  58 A with a near-radial bearing surface  59  on one side to resist rotation toward that surface, and a sloping bearing surface  59 A on the other side to permit rotation toward that surface. Pivotable latches  60 A with teeth  61 A engage the teeth  58 A of the axle retainer hub, urged by centrifugal and gravitation forces, but the near-radial and sloping surfaces either augment or prevent the locking action. The locking and disengaging action is automatic at all times. FIG. 12 shows that the rotatable latches of this alternate design have been rotated by centrifugal force and that the teeth of these latches are in contact with the near-radial sides of the teeth of the toothed integral axle retainer, and that the wheel is not free to rotate in this direction. FIG. 13 shows that the rotatable latches of this alternate design have been rotated by centrifugal force but that the teeth of these latches are in contact with the sloping sides of the teeth of the toothed integral axle retainer, and that the wheel is free to rotate in this direction. 
     With reference to FIGS. 15A,  15 B,  15 C,  15 D and  15 E, a further alternate form of the invention is shown. 
     An outer clutch plate  73  is bolted to the inner face of a wheel such as wheel  14 A by suitable bolts extending through holes  74 ′ shown in FIG.  15 B. An inner clutch plate  76 ′ is bolted to the inner face of a hub by suitable bolts through holes  78 ′ (FIG.  15 A). 
     FIG. 15A shows groups of slots  82  in the face of inner clutch plate  76 ′. The slots  82 A,  82 B,  82 C,  82 D and  82 E are radially and laterally spaced so that the arc between opposite ends of slots  82 E is approximately 3°. 
     Groups of one-way clutch teeth  84  comprised of teeth  84 A,  84 B,  84 C,  84 D and  84 E are radially aligned on outer clutch plate  73  and are adapted to engage slots  82 A- 82 E in inner clutch plate  76 ′ to restrict the rotation of one wheel in one direction with respect to the wheel on the other end of the wheel. A left hand clutch and a right hand clutch will be required, one for each wheel. These clutches are shown in U.S. Pat. Nos. 5,070,978 and 5,597,057, except that they do not have the above 3° increment of engagement. The groups of teeth  84  are positioned on radii separated typically at 30° intervals. 
     With reference to FIGS. 15E and 15D, (see the &#39;978 Patent, FIGS. 5 and 6), a typical tooth  84 C is pivotally mounted in an underlying tapered slot  84 C′. Each tooth in group  84  pivots about fulcrum  85  dwelling in slot  86  of compatible shape. While as any given slot such as  82 C is not in radial alignment with any given slot such as  84 C′, the tooth  84 C will remain entirely recessed in slot  84 C′. Each tooth can be spring-biased as disclosed in &#39;057 patent FIGS. 6-9. 
     Thus, if plate  73  is rotated clockwise, as indicated by arrow  88  in FIG. 15C, the tooth  84 C will pass over the slot  82 C without engaging the slot  82 C. If the plate  73  is rotated fast enough, the teeth will not even have much time to momentarily pivot into slots  82 C. On the other hand, if plate  73  is rotated counterclockwise, in the opposite direction to arrow  88 , there will be a first slot  84 C which radially aligns itself with slot  82 C before any other slots do so. When this occurs, the tooth  84 C in that first slot  84 C′ will pivot upward towards its biased position until its forwardmost lengthwise edge  90  engages slot  82 C, thereby causing plate  76 ′ to rotate with plate  73 . Again, this phenomenon is shown by the &#39;978 and &#39;057 patents. 
     It will be understood that alternative automatically operating latching mechanisms and restraints may be employed as mechanical equivalents without departing from the spirit of the invention. FIG. 15E shows the foregoing clutch plates  73  and  76  adapted to press-on hubs. 
     A further alternate form of the invention is shown in FIGS. 15E and 17. A press-on hub  60 ′ has a cylindrical body  62 ′, an inner bore  64 ═, opposite faces  66 ′ and  68 ′, and a plurality of threaded apertures  70 ′ in each of the faces (FIGS. 15E and 16 and  17 ). The diameter of bore  64 ′ frictionally receives the outer diameter of an axle which is force-fit within bore  64 ′. The hub  60 ′ is shown in assembled condition in FIG.  15 E. 
     Among the advantages of press-on hubs  60 ′ are the following: 
     1. They are less expensive than integral hubs because much machining is eliminated. 
     2. Hubs  60 ′ reduce the diameter of the axle, which further reduces cost. 
     3. Most parts can be identical for all wheel diameters with hubs  60 ′. 
     4. The hubs  60 ′ can be replaced without replacing the axle. 
     5. The hubs  60 ′ can be made of different material than the axle, and different suppliers of hubs are then available for a given axle. 
     A further embodiment of the invention is shown in FIGS. 18-20. This embodiment is similar to that of FIGS. 12 and 14 except that a bolt-on latch pin plate  72 B is mounted adjacent plate  76  and secured to wheel  14 A by bolts  74 B (FIG.  20 ). Threaded apertures  72 C (FIG. 20) receive threaded latch plate pins  72 D. Two-piece ratchet gear elements  76 B (FIGS. 18-20) with abutting edges  73 C are secured to hub  60 ′ by bolts  78 B. Creating two ratchet gear elements permits them to be installed after other components without disturbing the other components. Rotating latches  60  are omitted from FIG. 20 for clarity. 
     This invention herein can be applied to locomotive and/or powered axles as well as to railroad car axles. 
     From the foregoing, it is seen that all the objectives of this invention are met.