US3831775A

US3831775A - Draft gear assembly for locomotives and the like

Info

Publication number: US3831775A
Application number: US00202825A
Authority: US
Inventors: V Hawthorne
Original assignee: Keystone Industries Inc
Current assignee: Keystone Industries Inc
Priority date: 1971-11-29
Filing date: 1971-11-29
Publication date: 1974-08-27
Anticipated expiration: 1991-08-27

Abstract

A draft gear assembly for a locomotive or other railroad vehicle, wherein a hydraulic unit is mounted in a yoke and is arranged to cushion the impact of buff and draft loads applied to a coupler connected to the yoke. A plurality of return springs are mounted in the hydraulic unit so that the overall size of the assembly is reduced to fit a conventional locomotive draft gear pocket. A plurality of resilient pads are mounted in cavities in the coupler end of the yoke, and exert an aligning or centering force on the coupler when the coupler swings a predetermined number of degrees in either direction from a centered position. Such aligning or centering force is exerted on the coupler through one or the other of a pair of laterally spaced, longitudinally shiftable alignment plungers in the yoke. Cushioning and dissipation of the impact force of large buff and draft loads is achieved by restricting the flow of hydraulic fluid in the hydraulic unit of the draft gear assembly, such flow passing through orifices of a particular size and arrangement in the cylinder of the hydraulic unit to an internal reservoir in the unit and then to an external reservoir. Smaller, train handling loads are cushioned primarily through compression of a compressible liquid in the hydraulic unit, when such liquid is utilized as the hydraulic fluid.

Description

Tlnite States Eatent 1 [451 Aug. 27, 1974 Hawthorne DRAFT GEAR ASSEMBLY FOR LOCOMOTIVES THE LIKE [75] Inventor: Vaughn T. Hawthorne,

Mechanicsburg, Pa. [73] Assignee: Keystone Industries, Inc., Chicago,

Ill.

[22] Filed: Nov. 29, 19711 [21] Appl. No.: 202,825

[52] 11.8. Cl 213/43, 213/8, 213/69, 267/65 R [51] llnt. C1. B6lg 9/08, 861g 9/16 [58] Field of Search 213/8, 43, 67, 69; 267/64 R, 65 R, 124, 127

[56] References Cited UNITED STATES PATENTS 7 1,955,349 4/1934 Stevens 213/43 2,732,898 1/1956 Taylor 267/124 2,948,413 8/1960 Zanow 213/43 3,117,675 1/1964 Price et al 213/43 3.160285 12/1964 Sinclair et a1. 213/43 3,166,201 1/1965 Wallace et a1. 213/43 3,204,945 9/1965 Taylor 267/64 R 3,220,561 11/1965 Blake 213/43 3,400,834 9/1968 Zanow 213/8 3,412,869 11/1968 Wallace et a1. 213/43 3,568,855 3/1971 Seay....'. 213/43 3,589,528 6/1971 Stephenson... 213/43 3,618,928 11/1971 Taylor 267/65 R Primary Examiner-Drayton E. Hoffman Attorney, Agent, or Firm-Hibben, Noyes & Bicknell ABSTRACT A draft gear assembly for a locomotive or other railroad vehicle, wherein a hydraulic unit is mounted in a yoke and is arranged to cushion the impact of buff and draft loads applied to a coupler connected to the yoke. A plurality of return springs are mounted in the hydraulic unit so that the overall size of the assembly is reduced to fit a conventional locomotive draft gear pocket. A plurality of resilient pads are mounted in cavities in the coupler end of the yoke, and exert an aligning or centering force on the coupler when the coupler swings a predetermined number of degrees in either direction from a centered position. Such align ing or centering force is exerted on the coupler through one or the other of a pair of laterally spaced, longitudinally shiftable alignment plungers in the yoke.

Cushioning and dissipation of the impact force of large buff and draft loads is achieved by restricting the flow of hydraulic fluid in the hydraulic unit of the draft gear assembly, such flow passing through orifices of a particular size and arrangement in the cylinder of the hydraulic unit to an internal reservoir in the unit and then to an external reservoir. Smaller, train handling loads are cushioned primarily through compression of a compressible liquid in the hydraulic unit, when such liquid is utilized as the hydraulic fluid.

11 Claims, 16 Drawing Figures DRAFT GEAR ASSEMBLY FOR LOCOMOTIVES AND THE LIKE This invention relates to a draft gear for a railroad vehicle, and more particularly relates to a compactly arranged draft gear assembly for cushioning the impact of buff and draft loads imposed on a locomotive or other railroad vehicle.

Various types of railroad draft gears have been heretofore advanced for cushioning the impact of buff and draft loads exerted on railroad cars to prevent damage to the underframe structure of the cars and cargo car ried therein. Examples of some early types of draft gears or rigging are disclosed in the Gilman et al Pat. No. 1,073,578, Peterson Pat. No. 720,472 and Ross et a1 Pat. No. 1,200,526 patents. The Gilman et al patent discloses a draft rigging wherein only coil springs are utilized as cushioning elements. Thus, the Gilman et al structure is incapable of dissipating any substantial amount of impact energy. The Peterson and Ross patents are illustrative of draft gears in which springs and hydraulic fluid are utilized as the cushioning elements. However, these early combination draft gears were large, bulky devices for the load handling and energy absorbing capacities thereof and hence could not be made to fit in the draft gear pocket of a locomotive and provide the required cushioning capacity.

Railway draft gears heretofore advanced have also employed some form of alignment control structure to exert a centering force on the associated coupler and to limit the maximum extent of lateral swing of the coupler in either direction from a centered position. Two examples of structures utilized to effect coupler arm centering are disclosed in the Regan Pat. No. 1,648,325 and Metzger Pat. No. 2,754,978 patents. While the alignment control structures disclosed in these and other patents were generally satisfactory for their intended purpose, they were disadvantageous from the standpoint that the resilient elements or members thereof were difficult to remove and/or replace when necessary.

Finally, the structure utilized in the draft gears of the prior art for retaining the coupler pin in place were fre quently cumbersome and difficult to operate when it became necessary to remove the coupler pin for inspection and/or replacement. A typical coupler pin retaining arrangement having the aforementioned defrciences, is disclosed in the Wolfe Pat. No. 2,544,288.

Accordingly, it is a general object of the present invention to provide a novel and improved draft gear assembly for a railway vehicle, particularly a locomotive, which overcomes the aforementioned disadvantages of the prior art.

Another object is to provide a novel draft gear assembly which is more compact and lighter in weight than the draft gears thus far advanced of comparable capacity.

A further object is to provide a novel draft gear assembly for a railway vehicle, which utilizes a hydraulic unit to cushion and dissipate a substantial portion of the energy of large impact loads applied to an associated coupler and which also utilizes the compressibility of liquid in the hydraulic unit of the assembly to cushion low impact or train handling loads.

Still another object is to provide a novel draft gear assembly which will accommodate a relatively large amount of swing of the coupler in either direction from a centered or neutral position when the assembly is subjected to draft loads, but which will begin to offer resistance to swinging movement of the coupler in either direction from a centered or neutral position after only a few degrees movement when the coupler is sub jected to buff loads.

Afurther object is to provide a novel draft gear as sembly of the foregoing character, which utilizes at least one elastomeric pad for resisting swinging of the coupler to either side of a centered position when the coupler is subject to buff loads and wherein the paid is easily removable for inspection and/or replacement.

Still another object is to provide a novel draft gear assembly in which the coupler pin thereof is releasably retained in place in a novel and simplified manner.

A still further object is to provide a novel railway draft gear assembly, which is simple in construction, reliable in operation, and economical to manufacture.

Other objects and advantages of the invention will become apparent from the following detailed description and accompanying sheets of drawings, in which:

FIG. I is a side elevational view, in full and broken lines and with portions thereof broken away, of a draft gear assembly for a locomotive and embodying the features of the present invention, such assembly being shown mounted in a pocket at one end of the center sill of the vehicle, the center sill and adjacent structure which defines the pocket being shown in phantom lines;

FIG. 2 is a top plan view in full, broken and phantom lines and with portions thereof broken away, of the draft gear assembly and pocket shown in FIG. 1;

FIG. 3 is an enlarged longitudinal sectional view of a portion of the draft gear assembly shown in FIG. 2 and taken substantially along the lines 3-3 of FIG. 2;

FIG. 4 is a horizontal sectional view, on an enlarged scale, taken along the line 44 of FIG. 1',

FIG. 5 is an end view, on a reduced scale, of the cylinder of the hydraulic unit of the draft gear assembly shown in FIG. 3 and showing the circumferential location of the orifices therein;

FIG. 6 is a diagrammatic layout of the arrangement of the orifices in the cylinder of the hydraulic unit;

FIG. 7 is an enlarged, vertical sectional view taken along the line 7-7 of FIG. 3;

FIG. 8 is a fragmentary, longitudinal sectional view taken along the line 8-8 of FIG. 4;

FIG. 9 is a transverse sectional view taken along the line 99 of FIG. 4;

FIGS. 10-13, inclusive, are a series of diagrammatic views of the hydraulic unit of the draft gear assembly, and showing the parts thereof in the positions they would occupy during different phases of operation of the assembly; and

FIGS. 14-16, inclusive, are a series of semidia grammatic horizontal sectional views of the draft gear assembly and showing the parts thereof in the positions they occupy when the coupler is disposed at different angles from a centered or neutral position and subjected to draft and buff loads.

In FIGS. l and 2, a draft gear assembly 20 embodying the features of the present invention, is illustrated. The draft gear assembly 20 is shown mounted on a carrier 21 which, inturn, is secured in a pocket at one end of an associated railway vehicle. In the present instance,

the pocket is formed in one end of the center sill of a locomotive, and the carrier 21 is secured in the pocket by bolts 23 which extend through a pair of laterally extending ears 24 on the sides of the carrier 21 and through the adjacent structure of the center sill. An uncoupling mechanism 26 is shown mounted on the end wall, indicated at 27, of the locomotive.

Referring now to FIGS. 3 and 4 in conjunction with FIGS. 1 and 2, it will be seen that the draft gear assembly 20 comprises a yoke 32 which includes a body portion 33 having transversely spaced upper and

lower walls

34 and 36, respectively, spaced apart to provide a cavity for carrying a hydraulic unit to be described hereinafter, and open sides. The outer or right end wall, indicated at 37, of the body portion 33 is arcuate in a vertical plane, and the inner or coupler end, indicated at 38, of the yoke 32, as seen in FIGS. 1-4, is trifurcated to receive the bifurcated end portions, indicated at 39, of a coupler 42. The bifurcated end portions 41 of the coupler 42 are pivotally connected to the trifurcated end portions, indicated at 3811-380, of the yoke 32 by a coupler pin 43.

A lost motion connection is provided between the yoke 32 and coupler 42 so that a predetermined amount of relative longitudinal movement may take place therebetween. To this end, the trifurcated end portions 3811-380 of the yoke 32 are provided with vertically aligned openings 45 into which bushings 46 are pressed or otherwise secured. The openings. indicated at 47, in the bushings are oval with their longer dimensions extending longitudinally of the yoke to permit a limited amount of longitudinal movement of the coupler pin 43 therein. The coupler pin 43, however, closely fits a pair of vertically aligned, circular openings 48 in the bifurcated end 41 of the coupler 42 which precludes relative movement therebetween. Thus, the coupler pin 43 and the coupler 42 are capable of a predetermined amount of longitudinal movement relative to the yoke 32. The reason for providing for such relative longitudinal movement will be described hereafter. In FIG. 3, the coupler 42, yoke 32 and coupler pin 43 are shown in the positions they would occupy when the draft gear assembly 20 is unloaded, that is when no load is applied to the coupler 42, or the coupler is subjected to a normal draft load.

In order to facilitate removal of the coupler pin 43 for inspection and/or replacement, a novel coupler pin retaining structure is provided. Such retaining structure comprises a pair of laterally spaced, depending lugs 52 (FIGS. 3, 8 and 9) disposed in general longitudinal alignment with and below the

openings

47 and 48 in the interengaged end portions of the yoke 32 and coupler 42. The lugs 52 are provided with transversely aligned openings 53 therethrough for receiving a retaining bar 54. The retaining bar 54 is of a somewhat greater length than the transverse spacing of the lugs 52 so that the ends of the bar 54 are fully supported by the margins of the openings 53. As shown in FIGS. 3 and 8, the shape of the openings 53 and the cross section of the bar 54 is rectangular. However, some other noncircular shape could also be utilized.

An elongated abutment in the form of a locking plate 56 (FIGS. 3 and 9) is detachably secured to the front face of the bar 54 as by a bolt 57 and nut 58, the plate 56 and bar 54 being provided with appropriate bores therethrough for this purpose. The plate 56 is of a thickness greater than the clearance between the periphery of the bar and the margin of the openings 53. Consequently, the bar 54 cannot be shifted endwise through the openings 53 when the plate 56 is secured thereto. In addition, the length of the plate 56 is such as to prevent the bar 54 from being shifted laterally in the openings 53 by an amount sufficient to disengage either end of the bar from the openings 53. Consequently, when the plate 56 is secured to the retaining bar 54 by the bolt 57 and nut 58, the bar 54 cannot be moved from its engaged position in the lugs 52 and the coupler pin 43 likewise cannot be removed from its engaged position in the openings.

To remove the coupler pin 43 from its engaged position with the yoke 38 and coupler 42, it is a simple matter of unthreading the nut 58 from the bolt 57, and thereafter removing the retaining plate 56 and bolt 57 from the bar. The bar 54 is then shifted laterally in the openings 53 to disengage the bar 54 from the lugs 52. The coupler pin 43 is then free to drop out through the bottom of the assembly for inspection and/or replacement. Replacement of the coupler pin is accomplished by a reversal of the above steps. Upward movement of the coupler pin 43 is limited and disengagement thereof from the

bores

47 and 48 is prevented by a lip 49 (FIGS. 3, 8 and 9) or the yoke 32.

The draft assembly 20 includes a hydraulic unit, indicated generally at 60, for cushioning buff and draft loads applied to the coupler 42 by absorbing and dissipating all or most of the impact energy from the coupler. Such hydraulic unit comprises a pair of relatively movable members, namely, a reservoir and cylinder assembly 62 and a piston rod head 63, which are positioned in the cavity of the yoke body 33 between the

walls

34 and 36 as shown in FIGS. 1-4, inclusive. The reservoir and cylinder assembly 62 includes an enlarged central portion 64 (FIGS. 2 and 4) having a cavity 65 therein. The outer surface, indicated at 66, of the end wall, indicated at 58, of the central portion 64 may be convex in a vertical plane, as shown in FIG. 3, and a complimentally contoured, axially inwardly projecting pad 67 (FIG. 3) may be provided on the inner surface of the end wall 37 of the yoke body portion 33. The central portion of the outer surface, indicated at 61, of the piston rod head 63 may likewise be convex in a vertical plane, and a complimentally contoured, axially inwardly projecting pad 68 (FIG. 3) may be provided on the coupler end of the yoke cavity. The convex surfaces 61 and 66 permit a degree of relative pivotal movement between the hydraulic unit and the yoke 32 due to vertical movement of the coupling end of the coupler 42.

In order to define a reservoir and cylinder in the assembly 62, a sleeve 69 is mounted in the cavity in the central portion 64 thereof. The sleeve 69 is circular in cross section and has its axially inner end engaged with and supported on a circular recess 59 (FIG. 3) at one end of the cavity. The opposite end of the sleeve 69 is supported by a pilot portion 70 on one side of a reservoir head 71, the head 71 being fixedly secured in the open end of the cavity 65 as by welding 72. A pin 73 (FIG. 3) prevents rotation of the sleeve 69 in the cavity 65. When mounted in the cavity 65, the inner surface, indicated at 74, of the sleeve defines a cylinder in the assembly 62, and the space, indicated at 75, between the outer surface of the sleeve 69 and the adjacent surface of the cavity 65 comprises a reservoir. The cavity 65 is non-circular in transverse cross section,

and is preferably generally rectangular. Consequently, the reservoir 75 has four radially enlarged, circumferentially spaced portions 75a75d (FIG. 7). The radial dimension of the portions of the reservoir 75 between the radially enlarged portions 75a-75d is much less than the radial dimension of the portions 75a-75d, due to the aforementioned cross sectional shapes of the cavity 65 and sleeve 69 and the close fit of the sleeve in the cavity.

A piston 77 having a seal ring 78 in the outer periphery thereof, is shiftably mounted in the sleeve 69, and defines a pair of

chambers

80 and 81 on opposite sides thereof. The piston 77 is secured to an end portion 88 of a cylindrical piston rod 90 through an intermediate bushing 91. In the present instance, the bushing 91 is welded, as at 92, to the end portion 88 of the rod and also to the piston 77.

Since the rod 90 extends through the chamber 81, the rate of decrease in volume of the chamber 80 is greater than the rate of increase in volume of the chamber 81 as the piston 77 moves toward the right, as viewed in FIGS. 3 and 4. Such relationship is utilized to advantage in the operation of the draft gear assembly 20, in a manner to be described more fully hereinafter.

The piston rod 90 is supported in the reservoir head 71 by a bearing and seal assembly 93, the latter including a high pressure seal assembly 94 and a wiper 96. The assembly 93 is releasibly retained in an axially extending mounting boss 95, integral with the head 71, by a snap ring 97. The opposite end, indicated at 98, of the rod 90 is of a reduced diameter and extends through a central opening 102 in the rod head 63.

In order to permit the head 63 to rock on the end 98 of the rod 90, the end 98 is loosely received in the opening 102, and the end face, indicated at 103, of the full diameter portion of the rod 90 adjacent to portion 98, is beveled or chamfered. The end 98 of the rod 90 is retained inthe rod head 63 by a washer I04 and snap ring 105.

In order to provide clearance for the mounting boss 95 of the reservoir head 71 when the assembly 62 and head 63 have moved into engagement with each other, the rear or inner surface. indicated at 110, of the head 63 is provided with a central recess 112. The stroke of the piston 77 is such that the rear or inner surface 110 of the head 63 will engage the opposite end face surfaces, indicated at 113 and 114 in FIGS. 3 and 4, of the reservoir head 71 and central portion 64, respectively, before the piston 77 contacts the inner surface, indicated at 111, of the end wall of the central portion 641. The aforementioned limit positions of the rod head 63 and piston 77 are shown in broken lines in FIG. 3 and indicated at 63 and 77, respectively.

In order to cushion forces applied to the coupler, the hydraulic unit 60 coacts with the coupler 42 through the yoke 32 and also coacts with the center sill 22 and adjacent structure of the railway vehicle through the assembly 62 and head 63. These members have portions, indicated at 122 and 123 (FIGS. 2 and 4), that project beyond the body portion 33 of the yoke 32. The

portions

122 and 123 are in the form of lugs for engaging restraining structure on the vehicle. In the present instance. such restraining structure comprises two pairs of stops 124 and 125 (FIG. 2) respectively secured to the sides of the sill pocket so as to be engageable with the

lugs

122 and 123 in the manner hereinafter described.

The

lugs

122 and 123 also provide convenient mountings for spring means for returning the parts of the hydraulic unit 60 to the positions thereof shown in full lines in FIGS. 3 and 4 after the draft gear assembly 20 has been subjected to a buff or draft load. To this end, each pair of

lugs

122 and 123 is provided with at least one pair of longitudinally aligned bores in the end faces 126 and 127 thereof, respectively. In the present instance, two pairs of longitudinally aligned bores 128 and 129 (FIGS. 41 and 7) are provided in the pairs of

lugs

122 and 123 for receiving two pairs of double ele ment, concentric springs 130, the elements of each spring 130 being indicated at 1.32 and 133, respectively. The springs 130 thus serve to force the assembly 62 and head 63 apart and return them to their separated positions after a buff or draft load has caused the

members

62 and 63 to move toward or into engagement with each other. To this end, the springs 130 in this embodiment are placed under a total compressive preload of about 10,040 pounds.

It will be noted from FIGS. 4 and 7 that the return springs 130 are located between and carried by portions of the hydraulic unit 60. Such relationship reduces the transverse width of the assembly and thus contributes to the overall compactness of the structure.

The draft gear assembly 20 is capable of cushioning the impact of both large and small buff and draft loads applied to the coupler 42. However, the manner in which the assembly 20 cushions small impacts differs from the manner in which it cushions large impacts, although the same structure is used to cushion small impacts as is used to cushion large impacts.

Thus, for cushioning the impact of buff and draft loads, the sleeve 69 of the hydraulic unit is provided with orifice means to permit fluid :In the chamber 80 to be forced into the reservoir as relative movement occurs between the piston 77 and sleeve 69 due to the application of a buff or draft load on the coupler 42. Such orifice means comprises at least one and preferably a plurality of orifices in the sleeve 69 and respectively identified at 132137 in FIGS. 3-6. In the present instance, the orifices areformed by drillings, which are arranged as shown in the layout diagram of FIG. 6. The axial arrangement of the orifices is such that most of them are covered or out of registry with the chamber as the piston 77 reaches the end of its travel in the sleeve 69. Thus, if either a buff force is applied to the piston rod head 63, or a draft force is applied to the reservoir and cylinder assembly 62, a progressively greater resistance to relative movement of the piston 77 and end wall 58 toward each other will occur. At its maximum travel, the seal ring 87 of the piston will have moved past and covered the orifices 132135. Only a portion of the orifice 136 will be covered and the orifice 137 will remain uncovered. By way of example, the orifices 132-137 are about 0.0343 inches in diameter, the inside-diameter of the sleeve 69 is about 9.5 inches and the piston has a stroke of about 3.75 inches.

Working fluid displaced from the chamber 80 through the orifices 132-137 by relative movement of the piston 77 toward the right, as viewed in FIGS. 3 and 4, tends to cause a like amount of fluid in the reservoir 75 to be returned to the chamber 81 behind the piston 77. Communication between the chamber 81 and the reservoir 75 is provided by four fluid return openings or bores 142-145, inclusive, which are large relative to the orifices 132137 and thus have relatively small effect on the flow of working fluid into and out of the chamber 81. The reservoir 75 thus comprises conduit means connecting the

chambers

80 and 81 and permitting fluid flow therebetween. Fluid flow through this conduit means is restricted, however, by the aforementioned close fit of the sleeve 69 in the cavity 65 between the radially enlarged portions 75a-75d of the reservoir 75.

It will be noted that, with the exception of the orifice 132 and the return opening 143, the circumferential arrangement of the orifices 132137 and openings 142-145 is such that the orifices and return openings are in general radial alignment with respective ones of the radially enlarged reservoir portions 75a-75d. Because of such alignment, a longer path is provided for the flow of hydraulic fluid through the reservoir 75.

With the foregoing structure, it is apparent that little or no relative movement could occur between the piston 77 and sleeve 99 ifthe hydraulic unit 60 were filled with an incompressible fluid. However, in order to permit the draft gear assembly to cushion the impact of small buff and draft loads imposed on the coupler 42, the unit 60 is preferably filled with a compressible liquid. An example of one compressible liquid suited for this purpose is Dow Corning 210 fluid, 0.65 centistoke grade. Such liquid is manufactured by and available from the Dow Corning Corporation, Midland, Michigan. Other liquids having similar or greater compressiblity characteristics could, of course, be employed instead of the aforementioned Dow Corning 210 fluid.

Thus, when a buff or draft load of a magnitude less than 250,000 pounds, for example, is imposed on the coupler 42, the liquid in the hydraulic unit 60 will be compressed and the piston 77 will move the cylinder 74 due to the reduction in volume of the liquid. Such compression takes place not only in the chamber 80, but also in the reservoir 75 and chamber 81, and cushions the force of the buff or draft load applied to the coupler.

While the compression of the liquid in the chamber 80, reservoir 75 and chamber 81 provides the primary cushioning effect at this time. an additional cushioning effect is also obtained as a result of the flow of some of the liquid in the chamber 80 through the orifices I32-137 into the reservoir 75. Thus, the compression of the liquid in the hydraulic unit 60 as well as the restriction of the flow of the liquid from the chamber 80 into the reservoir 75 serves to cushion the impact of small buff and draft loads imposed on the coupler 42.

As heretofore mentioned, the same structure of the draft gear assembly 20 that is utilized to cushion the impact of small buff and draft loads is also utilized to cushion the impact of larger buff and draft loads, that is, loads of magnitudes from between 250,000 to 750,000 pounds, for example. However, in order to cushion the impact of such larger loads, the piston 77 must travel a substantial distance in the sleeve 69. This degree of movement of the piston 77 could not take place unless some means were provided for accommodating or discharging excess working fluid displaced into the reservoir by the piston 77. To this end, the draft gear assembly 21) includes means in the form of an auxiliary external reservoir 146 (FIGS. 1 and 2) for this purpose.

The reservoir 146 may be of any desired construction and material, but is preferably of sheet metal. As shown in FIG. 1, the reservoir 146 is secured to the underside of the center sill 22 of the car, adjacent the pocket in the sill, but could be located elsewhere, if desired. The reservoir 146 is provided with a fluid inlet fitting 147, a fluid outlet fitting 148 and a combination breather and fluid filler tube 149. Only a portion of the tube 149 is shown in FIGS. 1 and 2, it being understood that the tube 149 extends to a convenient access point on the vehicle.

The inlet fitting 147 is connected by high pressure flexible hose 152 to a bypass valve assembly 153, which includes a valve element in the form of a ball 154 (FIGS. 10-14), and the valve assembly 153 is in turn connected to the reservoir through a tube 155 which communicates with the reservoir 75. Thus, one end of the tube 155 is threaded into the valve 153 and the opposite end thereof extends through an opening 156 (FIGS. 2 and 3) in the end wall 37 of the yoke 32 and is threaded into another opening 157 in the end wall 58 of the central portion 64 of the reservoir and cylinder member 62. The inner end of the opening 157 registers with an enlarged portion, such as the portion 74a (FIG. 7), of the reservoir space 75.

The outlet fitting 148 of the reservoir 146 is connected by means of another high pressure hose 158 to a check valve assembly 160 which includes a valve element in the form ofa ball 161 (FIGS. 1 and 10-14). The valve assembly 160 is threaded into an opening (not shown) in the end wall 67 of the member 62 and projects through a larger, co-axial opening (also not shown) in the end wall 37 of the yoke 32. The check valve 160 communicates with the reservoir 75, preferably the enlarged portion 75b.

The ball 154 of the bypass valve assembly is normally biased to a closed position by a spring (not shown) and, in this instance, is adjusted to open at an approximate pressure of 3,500 psi. Such pressure, in the present device, corresponds to a coupler force of approximately 250,000 lbs. for the aforementioned cylinder diameter of about 9.5 inches. The conditions under which the bypass valve assembly 153 opens to permit working fluid to be bypassed from the internal reservoir 75 to the external reservoir 146 in response to buff and draft loads of differing magnitudes, and the conditions under which the check valve assembly 160 opens and closes to control the flow of working fluid from the external reservoir 146 to the internal reservoir 75, will be better understood upon making reference to FIGS. 10-12, in conjunction with the preceeding figures.

Operation of The Hydraulic Unit In FIG. 10, the parts of the hydraulic unit 60, are shown in their normal operating positions. In this condition, the springs 130 maintain the piston and cylinder assembly 62 and the head 63 separated and against their respective pads or stops 67 and 68 in the yoke 32, and the piston 77- is disposed closely adjacent to the reservoir head 71. The bypass valve 154 which controls communication between the internal reservoir 75 and external reservoir 146 is closed, and the check valve 161 which permits working fluid to flow into the internal reservoir 75 from the external reservoir 146, is open.

In FIG. 11, the parts of the draft gear assembly 20 are shown in the positions they would occupy when the coupler of the assembly has been subjected to a relatively large buff or draft load. For the purposes of this description, it will be assumed that a buff load'has been applied to the coupler, thereby causing the rod head 63 to move with the yoke toward the piston and cylinder assembly 62. It will further be assumed that the magnitude of the buff force exerted on the coupler is such as to cause the piston 77 to travel through its full stroke in the sleeve 69. Thus, the piston 77 will move from position thereof shown in full lines in FIGS. 3, 4 and to the position thereof illustrated in broken lines in FIG. 3 and approximated in full lines in FIG. 11.

As the piston 77 begins its stroke, the pressure in the chamber 80, as well as in the reservoir 75 and chamber 81, rapidly increases. Such rapid increase is due to the fact that the rate of decrease of volume of the chamber 80 is greater than the rate of increase of the volume of the chamber 81. The check valve 161, of course, closes as soon as the pressure in the reservoir 75 begins to build up. As the pressure in the hydraulic unit 60 increases, the working fluid therein is compressed somewhat since the working fluid .is a relatively highly compressible liquid. Consequently, a portion of the impact force applied to the coupler of the draft gear assembly is cushioned by the compression of the liquid in the hydraulic unit 60.

When the pressure in the reservoir 75 reaches approximately 3,500 psi, the bypass valve 154 opens. Consequently, the excess working fluid displaced by the piston 77 from the chamber 80 flows through the high pressure flexible conduit 152 into the external reservoir 146. As the piston 77 continues to travel toward its FIG. 11 position, working fluid in the chamber 80 is forced at a rapid rate through the orifices 132 137 and into the reservoir 75. The restriction of this flow by the orifices cushions the force of the impact force and also causes a-substantial portion of the impact energy to be dissipated. The amount of such cushioning and energy dissipation increases as the 1 piston 77 continues its travel toward the end wall 58 since the orifices 132l35 are sequentially rendered ineffective to bypass working fluid to the reservoir 75.

In addition to the dissipation of energy resulting from the flow of working fluid through the orifices 132437, a portion of the energy of the impact force applied to the head 63 is also dissipated by the restricting action exerted by the bypass valve assembly 153 on the flow of working fluid to the external reservoir 146.

If the energy of the buff or draft load applied to assembly exceeds the cushioning and energy dissipating capacities thereof, the head 63 and reservoir and cylinder assembly 62 engage each other and the excess energy is transmitted to the center sill and undercarriage of the vehicle.

After the impact of a buff or draft load has been cushioned by displacement of working fluid from the chamber 80 and compression of the springs 130, the springs 130 tend to separate the head 63 and assembly 62 and return these members to their normal position illustrated in FIG. 10. FIG. 12 illustrates the positions of the

valves

154 and 161 and the directions of flow of working fluid in the hydraulic unit during this phase of operation. It will be noted that working fluid in the chamber 81 is flowing outwardly through the return bores 142-145 to the internal reservoir 75, and that working fluid is flowing into the reservoir from the external reservoir 146 through the conduit 158 and open check valve 161. The retunn stroke of the piston 77 is slowed by the restricting action of the orifices 132437 on the flow of working fluid returning to the chamber 80. Otherwise, an undesired rapid return stroke of the piston 77 might occur. When the piston 77 reaches its normal or full line position illustrated in FIGS. 3, 4 and approximated in 110, the hydraulic unit 60 is again ready to cushion the impact of another buff or draft load and to dissipate a substantial portion of the energy thereof.

FIG. 13 illustrates the positions of the parts of the hydraulic unit 60 when the assembly is subjected to rela tively small buff and draft loads such as usually occur during train handling. Such forces are insufficient to cause the pressure in the reservoir 75 to reach a valve sufficient to open the valve 154 but are sufficient to close the check valve 161. Consequently, working fluid in the unit 60 will not flow into or out of the external reservoir and cushioning of the small buff and draft forces is accomplished principally through compres sion of the working fluid which is a relatively highly compressible liquid.

Description of The Coupler Alignment Structure The draft gear assembly 20 also includes alignment control means for limiting the extent of lateral swinging movement of the coupler 42 in either direction from a centered or neutral position with respect to the longitudinal center of the yoke 32. Such centering is highly desirable, if not essential, in order to prevent twisting of the railroad vehicle body with respect to the track. When the draft gear assembly 20 is installed in a locomotive, coupler centering is of extreme importance during pusher or dynamic braking service in order to avoid derailment. I

The alignment control means of the draft gear assembly 20 thus comprises plunger means in the form of a pair of generally rectangularly-shaped plungers 162 and 163 (FIG. 4), respectively mounted in vertically extending, laterally spaced channells 164 and 165 in the trifurcated end 38 of the yoke 32. The

plungers

162 and 163 each have a transversely enlarged head 166 positioned in a transversely widened portion 167 in each channel. The portions 167 intersect a pair of vertically extending, generally

rectangular cavities

168 and 169 in the coupler end of the yoke 32, the

cavities

168 and 169 being open at their upper and lower ends 172 and 173, respectively. Means in the form of a pair of alignment pads 174 and 175 are respectively mounted in the

cavities

168 and 169 and are removable through the open lower ends 173 of the cavities.

The pads 174 and 175, in the present instance, are provided by a plurality of pieces of elastomeric material 177 bonded between a plurality of metal plates 178 to form a unitary assembly. The pads 174 and 175 are such as to offer a maximum resistance of 150,000 lbs. when compressed seven-eighths of 1 inch.

In order to retain the pads 174 and 175 in their operative positions in the

chambers

168 and 169, releasable retaining means in the form of a pair of keys 182 and 183 (FIGS. 3, 7 and 9), is provided. The

keys

182 and 183 extend longitudinally across the open lower ends 1730f the

cavities

168 and 169, and each is T-shaped in cross section and has a horizontal section 184 and a central, vertically depending section 186. A pair of

lugs

188 and 189 depend from the underside of the yoke 32 adjacent the coupler end of the cavity openings 173, and are provided with T-shaped openings 190 therein for receiving the

keys

182 and 183, as shown.

As best seen in FIG. 8, a portion 191 of the horizontal section 184 of each key extends into a transversely extending groove 193 in the body portion 33 of the yoke 32. Thus, the

keys

182 and 183 are supported at their respective ends by the grooves 193 in the body portion 33 and by the openings 190 in the

lugs

188 and 189.

In order to prevent accidental disengagement of the

keys

182 and 183 from their operative positions shown in FIGS. 8 and 9, the latter may be secured in such positions by cotter pins 194 extending through openings 196 in the depending sections 186 of the keys. The openings 196 are positioned closely adjacent to the inner sides of the

lugs

188 and 189 when the keys are fully engaged in the lug openings 190.

Assuming that the

keys

182 and 183 have been removed from their pad retaining positions shown in FIGS. 8 and 9, the pads 174 and 175 still can not be removed from the

cavities

168 and 169 until the retaining force exerted on the pads by two pairs of clearance take-up

plungers

198 and 199 is relieved. The pairs of clearance take-up

plungers

198 and 199 are mounted in axially extending bores 200 in the

alignment plungers

162 and 163, and are biased out of the bores 200 by coil springs 201 disposed around the

plungers

198 and 199 and engaging heads 202 thereon. While the primary purpose of the

plungers

198 and 199 is to take up slack in the parts of the draft gear assembly so that the maximum free play ofthe parts thereof does not exceed one-half of 1 inch, in accordance with Department ofTransportation rules, the

plungers

198 and 199 also serve to prevent the pads 174 and 175 from dropping out of the bottom of the cavities I68 and 169 when the

keys

182 and 183 are removed.

In order to relieve the pressure of the

plungers

198 and 199 on the pads 174 and 175, the ends thereof opposite from the heads 202 are axially internally threaded to permit headed screws (not shown), or some other suitable tool (also not shown), to be inserted through holes 203 in the outer end faces, indi cated at 204, of the

alignment plungers

162 and 163, and threaded into the take-up

plungers

198 and 199. Thus, the

plungers

198 and 199 may be retracted into their bores 203 until the pads 174 and 175 are free to drop through the open lower ends 173 of their

cavities

168 and 169. Access to the holes 203 in the

alignment plungers

162 and 163 will, of course, require removal of the coupler pin 43 and separation of the coupler 42 from the yoke 32.

Referring now to FIGS. 14-16, the manner in which the

alignment plungers

162 and 163 and alignment pads 174 and 175, exert a straightening or centering force on the coupler 42 when the latter is caused to swing laterally toward either side ofa centered position during buff and draft loads, will now be described.

In FIG. 14, the coupler 42 is shown in full lines as it would appear when the longitudinal center line thereof, indicated at 210, is aligned with the longitudinal center line, indicated at 211, of the draft gear assembly 20, and the coupler 42 is under a normal load. In this condition, the springs 201 of the clearance take-up

plungers

198 and 199 bias the

alignment plungers

162 and 163 longitudinally outwardly in the channels 164 and 165, or toward the left as seen in FIG. 14, so that the outer end faces, indicated at 204, of the

plungers

162 and 163 engage the adjacent convex end faces 212 and 213 of a pair of abutments on the pivot end of the coupler 42. Such abutments are preferably in the form of a transversely spaced pair of

ears

214 and 215. The springs 201 thus cause or tend to cause the coupler 42 to center with respect to the longitudinal center line 211 of the yoke 32 and also tend to maintain the coupler 42 shifted longitudinally forwardly or away from the yoke 32. Such longitudinal movement of the coupler 42 relative to the yoke 32 is provided for by the elongated openings 47 in the trifurcated end portions 38a-38c of the yoke.

Assuming that the coupler 42 is connected to another railroad vehicle and is then subjected to a draft load, the lost motion connection between the coupler 42 and yoke 32 is such that no aligning or centering force will be applied to either of the

ears

214 or 215 by the pads 174 and through their

respective alignment plungers

162 and 163 until the coupler 42 swings through an arc of approximately 12 in either direction from its centered position. Such angle is indicated in FIG. 14 between the longitudinal center line 211 of the yoke 32 and the longitudinal center line 210 of the broken line showing of the coupler indicated at 42. Since a 12 angle of swing of the coupler 42 in either direction from its centered position is required before any aligning or centering force is exerted thereon when the coupler is subjected to a draft load, it will be apparent that the coupler 42 is substantially free of centering forces during most draft load conditions.

In FIG. 15, the parts of the draft gear assembly 20 are illustrated in full lines in the positions they would occupy when the coupler 42 is centered and subjected to a light buff load insufficient to cause any significant movement of the piston 77 in the sleeve 69. Under these conditions, the coupler 42 will be caused to shift longitudinally toward yoke 32 to take up the clearance provided by the lost motion connection between the coupler 42 and the trifurcated end 38 of the yoke 32. Such shift causes the heads 166 of the

alignment plungers

162 and 163 to move into close proximity to but re main out of contact with the pads 174 and 175.

In the event that the coupler 42 is caused to swing laterally in either direction from the centered, full line position thereof illustrated in FIG. 15 to a position where the longitudinal center line 210 of the coupler 42 is disposed at an angle of 4 or more with respect to the longitudinal center line 211 of the yoke 32, one or the other of the

plungers

162 and 163 will begin to exert a centering force on their

respective ears

214 and 215. The latter condition is illustrated in FIG. 15 by the broken line position 42 of the coupler, and by the broken line position 162 of the plunger 162, for example. Thus, if the angle between the center line 210 of the coupler 42 and the center line 211 of the yoke 32 should exceed an angle of 4 when the coupler 42 is subject to light buff loads, a centering force will be applied thereto, which force will progressively increase as the coupler 42 swings further away from its centered position.

In FIG. 16, the parts of the draft gear assembly 20 are illustrated in full lines in the positions they would occupy when the coupler 42 is subjected to an off-center buff load of sufficient magnitude to cause full travel of the piston 77 in the sleeve 69 and to cause the coupler 42 to swing laterally by an amount such that the center line 210 thereof is disposed at an angle of 14 with respect to the center line 211 of the yoke 32. Such condition could occur during hard braking on a curve. When the coupler 42 swings through the latter mentioned degree of angularity, one or the other of the alignment pads 174 or 175 will be substantially completely compressed and will exert its maximum centering force on the coupler. As shown in FIG. 16, the pad 174- is compressed and is exerting its centering force on the cou pler ear 214 through the alignment plunger 162. Since either of the alignment pads 174 and 175 will exert a reaction force of about 150,000 pounds when fully compressed, a substantial straightening force is exerted on the coupler 42.

In the event that the coupler 42 should be subjected to an off-center buff load of sufficient magnitude to cause the angle between the center line 210 of the coupler 42 and the center line of the yoke 32 to exceed 14, one or the other of the

ears

214 and 215 will contact a respective one of a pair of

stops

216 and 217 in the trifurcated end 38 of the yoke. Such condition is illustrated by the broken line position 42 of the coupler. As shown in FIG. 16, the ear 214 is engaging the stop 216. While the stops 216 and 27 of the alignment structure of the draft gear assembly 20 will limit the lateral swing of the coupler 42 to a few degrees in excess of 14, such stops are only provided as a safety feature and normally do not function.

In order to protect and reinforce the parts of the alignment control means when the draft gear assembly 20 is in use, wear

plates

218 and 219 may be welded or otherwise secured to the sides of the trifurcated end 38 of the yoke 32, and elsewhere.

While the draft gear assembly 20 herein illustrated and described is primarily suited for use in a locomotive, it may also be used in other types of railroad vehicles, in an end-of-car installation, if desired.

Only one embodiment of the invention has been herein illustrated and described. However, it will be understood that modifications and variations thereof may be effected without departing from the concepts of the invention as exemplified by the appended claims.

1 claim:

1. A hydraulic draft gear assembly adapted to be mounted at one end ofa railway vehicle for cushioning the impact of buff and draft loads imposed on a coupler of said assembly. said draft gear assembly comprising a coupler connected to a yoke, said yoke having a hollow body portion, said body portion having transversely spaced walls defining a cavity therein, a pair of relatively longitudinally movable members in said cavity, each of said members having a pair of oppositely arranged lug portions extending laterally outwardly beyond said yoke body portion, and hydraulic cushioning means carried by said members and mounted centrally therein, said hydraulic cushioning means being operable to resist relative movement of said members toward each other, and at least one coil spring carried by each respective pair of said lug portions and normally biasing said members away from each other, said coil springs being located closely adjacent to said cushioning means and being arranged in longitudinally extending, laterally spaced relation with respect to said cush' ioning means, and said coil springs being disposed outside said yoke body portion when engaged with said lug portions, whereby said hydraulic draft gear assembly is of reduced size and weight for the load handling capacity thereof.

2. The hydraulic draft gear assembly of claim 1, in which said hydraulic cushioning means includes a cyl inder in one of said members and a piston movable in said cylinder and connected to the other of said mem bers, and the stroke of said piston is relatively short, whereby said hydraulic draft gear assembly is of reduced length.

3. The hydraulic draft gear assembly of claim 2, in which the stroke of said piston is about three and three quarters inches.

4. The hydraulic draft gear assembly of claim 1, in which said members have opposed flat end faces engageable with each other whenever the buff or draft loads on said coupler reach a predetermined maximum.

gagement of said end faces of said members prevents damage to said piston and cylinder.

6. The draft gear assembly of claim 2, in which said one member has a cavity therein, said cavity is noncircular in cross section, a sleeve having a cylindrical outer surface is mounted in said cavity and defines a reservoir encircling said sleeve and having at least one radially enlarged portion, said piston divides said cylinder into two chambers, at least one orifice is provided in said sleeve in substantial alignment with said radially enlarged portion of said reservoir, said orifice establishing communication between one of said chambers and said reservoir and being adapted to restrict hydraulic fluid flow from said one chamber into said reservoir, and at least one return opening is provided in said cylinder, said return opening establishing communication between said reservoir and the other of said chambers and permitting substantially unrestricted hydraulic fluid flow between said reservoir and the other of said chambers during relative movement between said piston and saidcylinder.

7. The draft gear assembly of claim 6, in which another reservoir is providcd for receiving excess hydraulic fluid displaced from said one chamber by relative movement between said piston and said cylinder, and a first fluid conduit is provided for connecting said other reservoir with said first mentioned reservoir.

8. The draft gear assembly of claim 7, in which a fluid pressure responsive valve is provided in said first fluid conduit, said pressure responsive valve preventing hydraulic fluid from flowing into said other reservoir until the pressure in said first mentioned reservoir reaches a predetermined value. v

9. The draft gear assembly of claim 8, in which the effective area of said piston is about 70.88 square inches, and said pressure responsive valve is set to open when the pressure in said cylinder reaches or exceeds 3,500 pounds per square inch.

10. The draft gear assembly of claim 8, in which a second fluid conduit connects said other reservoir with said first mentioned reservoir, and a check valve is provided in said second fluid conduit, said check valve being operable to prevent fluid flow from said first mentioned reservoir to said other reservoir but to permit fluid flow in the opposite direction.

11. A hydraulic draft gear assembly adapted to be mounted at one end of a railway vehicle for cushioning the impact of buff and draft loads imposed on said assembly, said draft gear assembly comprising a yoke, a coupler connected to said yoke, hydraulic cushioning means carried by said yoke and having a cavity therein, a sleeve mounted in said cavity and providing a cylinder, a piston in said cylinder and movable relative thereto in response to buff and draft loads imposed on said coupler, said piston dividing said cylinder into two chambers and being movable relative to said cylinder in one direction to reduce the volume of one of said chambers and to increase the volume of the other of said chambers when said hydraulic cushioning means is subjected to either a buff or draft load, the rate of decrease in volume of said one chamber being greater than the rate of increase in volume of said other chamher when said piston moves in said one relative direction, said cavity and said sleeve defining a reservoir therebetween connecting said one chamber with said other chamber, the inner surface of said cavity being non-circular in cross section and the outer surface of said sleeve being circular in cross section and sized to closely fit the interior of said cavity so that said reservoir has at least one portion of relatively small radial dimension, and said last mentioned portion of said rescrvoir being operable to restrict the flow of liquid flowing through said reservoir from said one chamber to said other chamber, and said chambers and said conduit means being substantially completely filled with a compressible liquid, whereby the cushioning action of said assembly is increased by the restricted flow of liquid through said reservoir when said assembly is subjected to train handling loads.

Claims

1. A hydraulic draft gear assembly adapted to be mounted at one end of a railway vehicle for cushioning the impact of buff and draft loads imposed on a coupler of said assembly, said draft gear assembly comprising a coupler connected to a yoke, said yoke having a hollow body portion, said body portion having transversely spaced walls defining a cavity therein, a pair of relatively longitudinally movable members in said cavity, each of said members having a pair of oppositely arranged lug portions extending laterally outwardly beyond said yoke body portion, and hydraulic cushioning means carried by said members and mounted centrally therein, said hydraulic cushioning means being operable to resist relative movement of said members toward each other, and at least one coil spring carried by each respective pair of said lug portions and normally biasing said members away from each other, said coil springs being located closely adjacent to said cushioning means and being arranged in longitudinally extending, laterally spaced relation with respect to said cushioning means, and said coil springs being disposed outside said yoke body portion when engaged with said lug portions, whereby said hydraulic draft gear assembly is of reduced size and weight for the load handling capacity thereof.

2. The hydraulic draft gear assembly of claim 1, in which said hydraulic cushioning means includes a cylinder in one of said members and a piston movable in said cylinder and connected to the other of said members, and the stroke of said piston is relatively sHort, whereby said hydraulic draft gear assembly is of reduced length.

3. The hydraulic draft gear assembly of claim 2, in which the stroke of said piston is about three and three-quarters inches.

5. The hydraulic draft gear assembly of claim 4, in which said hydraulic cushioning means includes a cylinder in one of said members, a piston movable in said cylinder, and a piston rod having one end connected to said piston and its opposite end connected to the other of said members, the stroke of said piston being less than the maximum travel of said members, whereby engagement of said end faces of said members prevents damage to said piston and cylinder.

6. The draft gear assembly of claim 2, in which said one member has a cavity therein, said cavity is non-circular in cross section, a sleeve having a cylindrical outer surface is mounted in said cavity and defines a reservoir encircling said sleeve and having at least one radially enlarged portion, said piston divides said cylinder into two chambers, at least one orifice is provided in said sleeve in substantial alignment with said radially enlarged portion of said reservoir, said orifice establishing communication between one of said chambers and said reservoir and being adapted to restrict hydraulic fluid flow from said one chamber into said reservoir, and at least one return opening is provided in said cylinder, said return opening establishing communication between said reservoir and the other of said chambers and permitting substantially unrestricted hydraulic fluid flow between said reservoir and the other of said chambers during relative movement between said piston and said cylinder.

7. The draft gear assembly of claim 6, in which another reservoir is provided for receiving excess hydraulic fluid displaced from said one chamber by relative movement between said piston and said cylinder, and a first fluid conduit is provided for connecting said other reservoir with said first mentioned reservoir.

8. The draft gear assembly of claim 7, in which a fluid pressure responsive valve is provided in said first fluid conduit, said pressure responsive valve preventing hydraulic fluid from flowing into said other reservoir until the pressure in said first mentioned reservoir reaches a predetermined value.

11. A hydraulic draft gear assembly adapted to be mounted at one end of a railway vehicle for cushioning the impact of buff and draft loads imposed on said assembly, said draft gear assembly comprising a yoke, a coupler connected to said yoke, hydraulic cushioning means carried by said yoke and having a cavity therein, a sleeve mounted in said cavity and providing a cylinder, a piston in said cylinder and movable relative thereto in response to buff and draft loads imposed on said coupler, said piston dividing said cylinder into two chambers and being movable relative to said cylinder in one direction to reduce the volume of one of said chambers and to increase the volume of the other of said chambers when said hydraulic cushioning means is subjected to either a buff or draft load, the rate of decrease in volume of said one chamber being greater than the rate of increase in volume of said otHer chamber when said piston moves in said one relative direction, said cavity and said sleeve defining a reservoir therebetween connecting said one chamber with said other chamber, the inner surface of said cavity being non-circular in cross section and the outer surface of said sleeve being circular in cross section and sized to closely fit the interior of said cavity so that said reservoir has at least one portion of relatively small radial dimension, and said last mentioned portion of said reservoir being operable to restrict the flow of liquid flowing through said reservoir from said one chamber to said other chamber, and said chambers and said conduit means being substantially completely filled with a compressible liquid, whereby the cushioning action of said assembly is increased by the restricted flow of liquid through said reservoir when said assembly is subjected to train handling loads.