US3929232A

US3929232A - End of car cushioning unit

Info

Publication number: US3929232A
Application number: US388330A
Authority: US
Inventors: William K Maccurdy
Original assignee: Evans Products Co
Current assignee: RAIL HOLDINGS Inc A CORP OF; RAIL HOLDINGS Inc Corp TRUST CENTER 1209 ORANGE ST WILMINGTON DE A CORP OF
Priority date: 1973-08-13
Filing date: 1973-08-13
Publication date: 1975-12-30
Anticipated expiration: 1992-12-30
Also published as: CA1036985A

Abstract

A hydraulic end of car cushioning device for use in railway freight cars. The device is intended for use between the coupler shank and car underframe of a fixed sill type car and is designed so as to provide a long cushioning stroke under high impact loads. A load responsive check valve is interposed in the metering system of the cushioning device for preventing changes in length of the unit under lower buff and draft forces as occur in train action.

Description

United States Patent [1 1 MacCurdy Dec. 30, 1975 [54] END OF CAR CUSHIONING UNIT [75] Inventor: William K. MacCurdy, Plymouth,

Mich.

[73] Assignee: Evans Products Company,

Plymouth, Mich.

[22] Filed: Aug. 13, 1973 [21] Appl. No.: 388,330

[52] US. Cl 213/43; 213/8 [51] Int. Cl. B6lg 11/12 [58] Field of Search 213/43, 8; 267/64 B, 64 A;

[56] References Cited UNITED STATES PATENTS 3,493,124 2/1970 Thompson 213/43 2/1972 Carlson et al 213/43 X 4/1973 Brambilla et a1. 213/43 X Primary ExaminerLloyd L. King Assistant Examiner-Michael Mar Attorney, Agent, or Firml-larness, Dickey & Pierce [57] ABSTRACT 14 Claims, 3 Drawing Figures US. Patent Dec. 30, 1975 $& \1

END OF CAR CUSHIONING UNIT BACKGROUND OF THE INVENTION This invention relates to a cushioning unit and more particularly to a. cushioning unit adapted for use at the ends of railway cars.

It has been the practice to upgrade existing, fixed sill railway cars by providing them with end of car cushioning devices. Hydraulic cushioning units have been proposed for this purpose. The cushioning unit, however, experiences widely differing types of loadings. When making up a train in a switching or classification yard, the car receives extreme shock loadings due to high velocity impacts. Under such conditions, it is desirable to provide an extremely long cushioning stroke to effectively absorb these impacts. Long stroke end of car cushioning units, however, are not desirable when the train has been made up and is in transit. The units have a tendency to extend the length of the train considerably during these conditions and cause considerable problems when the slack is taken up.

It is, therefore, a principal object of this invention to provide an improved end of car cushioning unit.

Another object of the invention is to provide an end of car cushioning unit that provides a long stroke under high impacts but which resists changes in length under lower loading.

It is a further object of the invention to provide an end of car cushioning unit that requires a predetermined force to be applied to it before its cushioning operation becomes effective.

SUMMARY OF THE INVENTION This invention is adapted to be embodied in an end of car cushioning unit that is adapted to be interposed between a coupler and the frame of a railway car for damping shock forces. The cushioning unit comprises a cylinder and a piston received within the cylinder and defining with the cylinder a chamber that is adapted to receive a fluid. Primary metering means adapted to pass fluid from the chamber at a restricted rate upon relative movement of the piston and the cylinder. Means are provided for precluding the flow of fluid through theprimary metering means until a predetermined force is applied to the cushioning unit.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal cross-sectional view taken through the end of a railway car having a cushioning unit embodying this invention with the car structure being shown in phantom.

FIG. 2 is an enlarged view showing the metering device of the cushioning unit as it appears under buff forces.

FIG. 3 is an enlarged view, in part similar to FIG. 2, showing the device as it appears when it experiences draft forces.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 illustrates an end of car cushioning unit embodying this invention, identified generally by the reference numeral 11. The end of car cushioning unit 11 is adapted to be interposed between a coupler shank 12 and the car under-frame 13. The installation may be accomplished in any of a variety of manners and, for this reason, the car structure has been shown only in phantom. Certain details of the illustrated installation will be described, but should only be considered as exemplary in nature.

The cushioning unit 11 includes a cylinder assembly 14 comprised of a cylinder head 15, a tubular cylinder 16 and a closure plug 17. The cylinder 16 defines a cylindrical bore 18 closed at one end by the cylinder head 15 and at the other end by the plug 17 to define a fluid receiving chamber 19.

The chamber 19 is divided into two sections by means of a piston assembly 21 that is slidably supported within the bore 18. The piston assembly 21 includes an orifice plate 22 that is affixed to a main piston 23 by means of bolts 24, only one of which appears in the drawings. An anti-friction bushing 25 engages the bore 18 and is trapped between outstanding flanges of the orifice plate 22 and the main piston 23. The piston 23 is also formed with an annular groove 26 in which a piston ring 27 is positioned to sealingly engage the bore 18.

A piston rod 28 is affixed in any known manner to the piston assembly 21 and extends through an opening 29 formed in the closure plug 17. A bushing 31 and seal assembly 32 carried by the closure plug 17 supports and sealingly engages the piston rod 28.

The piston rod 28 has affixed to its outer end a draft collar 33 that is trapped in a draft lug assembly, indicated by the reference numeral 34 that is fixed in any suitable manner to the under-frame of the associated railway car. The cooperation of the draft lug assembly 34 with the draft collar 33 couples the piston rod 28 and piston assembly 21 to the car under-frame 13. That is, the piston assembly 21 is held against any substantial movement relative to the under-frame structure 13.

The cylinder head 15 is formed at its outer end with a socket 35 that receives the coupler shank 12. Alligned openings 36 and 37 are formed on opposite sides of the socket 35 to receive a draft key (not shown) for fixing the coupler shank to the cylinder head 15. Thus, the cylinder assembly 14 is affixed for movement with the coupler shank 12. A stop block 38 is fixed to the under-frame 13 and is abuttingly engaged by the cylinder head 15 when the cushioning unit 11 is in its fully extended draft position (FIG. 1).

A metering rod 39 of predetermined configuration is affixed to the cylinder head 15 and extends concentrically into the cavity 19. An appropriately sized orifice opening 41 is formed in the orifice plate 22 for cooperation with the metering rod 39. The piston rod 28 is formed with an elongated cylindrical opening 42 that is alligned with the orifice opening 41 and which is adapted to receive, without restriction, the metering rod 39 at the extreme position of the piston assembly 21 relative to the cylinder assembly 14 in the buff condition.

In order to preclude relative movement of the piston assembly 21 and cylinder assembly 14 until large impact forces are received, there: is provided a pressure responsive valve assembly, indicated generally by the reference numeral 43 and shown in most detail in FIGS. 2 and 3. The pressure responsive valve assembly 43 includes one or more passages 44 that extend axially through the piston 23 between a cavity 45 formed between the main piston 23 and orifice plate 22 and an annular relief 46 formed in the main piston 23. The flow through the passage 44 is controlled by a conical disk spring valve member 47. In the non-flow condition the outer peripheral edge 48 of the valve member 47 sealingly engages the main piston 23. An opposite peripheral edge 49 sealingly engages a collar 51 that is received around a recess 52 at the outer end of the piston rod 28 and which is axially held in position by the main piston 23. As will become apparent, the valve member 47 acts as a two-way, pressure responsive valve.

The chamber 19 is partially filled with hydraulic fluid to a level indicated by the phantom line 53. Gas, such as Nitrogen, at a high pressure is charged into the cavity 19 above the oil level 53. The gas pressure acts as a return spring to hold the cushioning unit 11 in the position shown in FIG. 1. For a reason which will be come more apparent, one or more passages 54 extend through the collar 51 at a point radially inwardly of the valve member 47.

As has been noted, FIG. 1 illustrates the cushioning unit 11 in its normal installed position. Impact forces applied to the cushioning unit from the coupler shank 12 or from the car frame structure 13 via the draft lug assembly 34 tend to cause relative movement between the piston assembly 21 and the cylinder assembly 14. This relative movement can only be accomplished by forcing the oil through the orifice opening 41. If the valve assembly 43 were not provided, any force greater than the force required to overcome the gas pressure in the chamber 19 would result in such relative movement. Under low impact forces, such relative movement is undesirable since it will result in considerable changes in train length and attendant problems.

The valve 43, however, precludes any flow through the orifice opening 41 by blocking the passage 44 until a predetermined force is applied. When this predetermined force is reached, the pressure acting through the passage 44 on the valve member 47 will cause its peripheral edge 48 to deflect away from the main piston 23 as shown in FIG. 2 and permit flow. The metering rod 39 and orifice opening 41 will provide fluid resistance to continued movement, as is well known.

When the force is relieved, the valve member 47 will again move to its closed position. The gas pressure acting on the oil 53 will, however, cause the unit to return to its normal position (FIG. 1) since the oil can be forced through the restricted passage 54 past the closed valve assembly 43. This return will occur at an extremely slow rate.

In the event a draft force is exerted on the cushioning unit 11 before return to the normal position is reached, the cushioning unit 11 will also be operative to resist such forces. Rapid runout will be precluded by the closure of the valve 43. If the draft force is sufficiently large, however, the valve member 47 will deflect so that its peripheral portion 49 moves away from the collar 51 (FIG. 3) and permits flow back through the opening 41. Thus, it should be readily apparent that the valve assembly 43 acts as a pressure responsive valve for controlling flow in either direction through the orifice opening 41.

It is to be understood that the foregoing description is that of a preferred embodiment of the invention. Various changes and modifications may be made without departing from the spirit and scope of the invention as defined by the appended claims.

I claim:

1. An end of car cushioning unit adapted to be interposed between a coupler and a car frame of a railway car for damping shock forces, said cushioning unit comprising a cylinder, a piston received within said cylinder, said piston and said cylinder defining a chamber adapted to receive a fluid, primary metering means in communication with said chamber for passing fluid therethrough at a restricted rate upon relative movement of said piston and said cylinder, and pressure responsive valve means in series flow arrangement with said primary metering means for precluding the flow of fluid through said primary metering means until a predetermined force is applied to said cushioning unit.

2. An end of car cushioning unit adapted to be interposed between a coupler and a car frame of a railway car for damping shock forces, said cushioning unit comprises a cylinder, a piston received within said cylinder, said piston and said cylinder defining a first chamber adapted to receive a fluid, means defining a second chamber adapted to receive a fluid, primary metering means in communication with said chamber for passing fluid therethrough at a restricted rate upon relative movement of said piston and said cylinder, said primary metering means being adapted to experience flow in one direction upon relative movement of said piston and said cylinder in a first direction and in an opposite direction upon relative movement of said piston and said cylinder in an opposite direction, and means for precluding the flow of fluid through said primary metering means in each direction until a predetermined force is applied to said cushioning unit in the respective direction.

3. An end of car cushioning unit as set forth in claim 2 wherein the means for precluding flow through the primary metering means comprises pressure responsive valve means.

4. An end ofcar cushioning unit as set forth in claim 3 wherein the pressure responsive valve means comprises a single valve element movable between a closed position and an open position in response to a predetermined pressure.

5. An end of car cushioning unit as set forth in claim 4 wherein the valve element controls the flow in either direction through an associated passage.

6. An end of car cushioning unit adapted to be interposed between a coupler and a car frame of a railway car for damping shock forces, said cushioning unit comprising a cylinder, a piston received within said cylinder, said piston and said cylinder defining a chamber adapted to receive a fluid, primary metering means in communication with said chamber for passing fluid therethrough at a restricted rate upon relative movement of said piston and said cylinder, said primary metering means comprising an orifice and a cooperating metering rod, and means for precluding the flow of fluid through said primary metering means until a predetermined force is applied to said cushioning unit.

7. An end of car cushioning unit as set forth in claim 6 wherein the means for precluding flow through the primary metering means comprises pressure responsive valve means.

8. An end of car cushioning unit adapted to be interposed between a coupler and a car frame of a railway car for damping shock forces, said cushioning unit comprising a cylinder, a piston received within said cylinder, said piston and said cylinder defining a chamber adapted to receive a fluid and a gas under pressure acting on the contained fluid for exerting a restoring force on said cushioning unit, primary metering means in communication with said chamber for passing fluid therethrough at a restricted rate upon relative movement of said piston and said cylinder, means for precluding the flow of fluid through said primary metering means until a predetermined force is applied to said cushioning unit, and a bleed passage bypassing the means for precluding flow through said primary metering means for permitting a restricted rate of flow of the fluid.

9. A cushioning unit comprising a cylinder assembly defining the cavity adapted to receive a fluid, a piston supported for reciprocation within said cavity, an orifice opening extending through said piston for communicating flow between opposite sides of said piston, a metering rod affixed to said cavity and adapted to cooperate with said orifice, a passage extending through said piston in series with said orifice, pressure responsive valve means for controlling the flow through said passage for precluding flow through said orifice until a predetermined force is applied to said cushioning unit.

10. A cushioning unit as set forth in claim 9 wherein the pressure responsive valve means comprises a conical spring disk having its outer peripheral edge adapted to sealingly engage a first portion of said piston on one side of said passage and its inner peripheral edge adapted to engage a second portion of said piston on the other side of said passage.

11. A cushioning unit as set forth in claim 10 wherein the outer peripheral edge of the valve element is adapted to be deflected away from the first portion of the piston under the influence of sufficient force in one direction for precluding flow past said outer peripheral edge, the inner peripheral edge of said valve element being adapted to deflect away from sealing engagement with the second portion of the piston upon the application of sufficient force in the opposite direction to permit flow past said inner peripheral edge.

12. A cushioning unit as set forth in claim 11 further including a bleed passage extending through said piston for permitting return flow of fluid through the orifice at a restricted rate independently of the pressure responsive valve.

13. A damping apparatus comprising:

a cylinder having an elongated interior chamber with one end being open and the other end being closed;

a piston rod extending within said chamber, said piston rod being movable with respect to said chamber;

a piston head connected to said piston rod, said piston head including a first member fixed to said piston rod and extending laterally therefrom, said first member located adjacent the wall of said chamber but spaced therefrom to form a gap therebetween; damping medium located within said chamber in between said piston head and said closed end; second member mounted upon said piston head, said second member capable of being in contact with both said first member and the wall of said chamber, said second member includes means for permitting said first member to deflect in respect to said second member, upon a predetermined level of damping force being achieved said first member deflects thereby permitting said damping medium to be conducted through said gap past said first member.

14. The damping apparatus as defined in claim 13 wherein: said first member being annular, said gap being annular.

Claims

4. An end of car cushioning unit as set forth in claim 3 wherein the pressure responsive valve means comprises a single valve element movable between a closed position and an open position in response to a predetermined pressure.

13. A damping apparatus comprising: a cylinder having an elongated interior chamber with one end being open and the other end being closed; a piston rod extending within said chamber, said piston rod being movable with respect to said chamber; a piston head connected to said piston rod, said piston head including a first member fixed to said piston rod and extending laterally therefrom, said first member located adjacent the wall of said chamber but spaced therefrom to form a gap therebetween; a damping medium located within said chamber in between said piston head and said closed end; a second member mounted upon said piston head, said second member capable of being in contact with both said first member and the wall of said chamber, said second member includes means for permitting said first member to deflect in respect to said second member, upon a predetermined level of damping force being achieved said first member deflects thereby permitting said damping medium to be conducted through said gap past said first member.