CA1059071A - End of car cushioning unit - Google Patents
End of car cushioning unitInfo
- Publication number
- CA1059071A CA1059071A CA304,467A CA304467A CA1059071A CA 1059071 A CA1059071 A CA 1059071A CA 304467 A CA304467 A CA 304467A CA 1059071 A CA1059071 A CA 1059071A
- Authority
- CA
- Canada
- Prior art keywords
- cylinder
- piston
- car
- cushioning
- flow
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Fluid-Damping Devices (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
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 under-frame 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. More specifically there is provided a cylinder with a piston received in the cylinder and the piston and cylinder defining a chamber adapted to receive fluid. The metering system includes a primary metering device in communication with the chamber for passing fluid therethrough at a restricted rate upon relative movement of the piston and the cylinder. A pressure responsive valve is provided with the primary metering device for precluding the flow of fluid through the primary metering device until a predetermined force is applied to the cushioning device. A bleed passage bypasses the pressure responsive valve for permitting a restricted rate of flow of the fluid.
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 under-frame 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. More specifically there is provided a cylinder with a piston received in the cylinder and the piston and cylinder defining a chamber adapted to receive fluid. The metering system includes a primary metering device in communication with the chamber for passing fluid therethrough at a restricted rate upon relative movement of the piston and the cylinder. A pressure responsive valve is provided with the primary metering device for precluding the flow of fluid through the primary metering device until a predetermined force is applied to the cushioning device. A bleed passage bypasses the pressure responsive valve for permitting a restricted rate of flow of the fluid.
Description
lOS9C17~
This invelltion relates to a cushioning unit and more particularly to a cushioning unit adapted for use at the ends of railway cars.
This is a division of copending Canadian Patent Application Serial Number 206,788, filed August 12, 1974.
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 differe~t 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 stroXe 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.
An 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.
According to the present invention there is provided an end of car cushioning unit adapted to be lQS90~1 interposed between a coupler and a car frame of a railway car for damping shock forces, the cushioning unit including a cylinder and a piston received within the cylinder, the piston and cylinder defining a chamber adapted to receive a li~uid and a gas under pressure acting on the contained liquid for exerting a restoring force on the cushioning unit.
Primary metering means is in communication with the chamber for permitting flow therethrough at a restricted rate upon relative movement of the piston and the cylinder. Means are io provided precluding the flow through the primary metering means until a predetermined force is applied to the cushioning unit. A bleed valve bypasses the means for precluding flow through the primary metering means for permitting a restricted rate of flow of the liquid.
Figure 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.
Figure 2 is an enlarged view showing the metering device of the cushioning unit as it appears under buff forces.
Figure 3 is an enlarged view, in part similar to Figure 2, showing the device as it appears when it lC~S9~71 experiences dr~ft forces.
Figure 1 illustrates an end of car cusllioning 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 underframe 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 i'lustrated installation will be describedj 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 pluq 17. The cylinder 16 defines a cylindrical bore 18 closed at one end by the cylinder head lS 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 assembl~ 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 antifriction 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 t0 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 sea; assembly 32 carried by the closure plug 17 supports and seal~ngly 1059C~7~
engac3cs the pj.C;ton rod 2~.
The piston rod 2~ has affixed to its outer end a draft collar 33 that is trapped in a draft lug asscmbly, ind.icated by the rcference numeral 34 that is fixed in any suitable manner to the ùnderframe 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 underframe 13. That is, the piston assembly 21 is held against any substantial movement relative to the underframe structure 13.
The cylinder head 15 is formed at its outer end with a socket 35 that receives the coupier 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 fixedcto the underframe 13 and is abuttingly engaged.by the cylinder head 15 when the cushioning unit 11 is in its fully extended draft position (Figure 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 aligned 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 presponsive valve assembly, indicated generally by the reference numberal 43 and 1059(~71 shown in most detail in Figures 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 sprlng valve member 47. In the nonflow condition the outer peripheral edge 48 of the valve member 47 sealingly engages the main piston 23. An opposite peripheral edge 49 sealingly engages 10. 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 a liquid in the form'of a 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 Figure 1. For a reason which will become 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, Figure 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 pres-sure in the chamber 19 would result in such relative movement.
~k ' ~r ~ - 5 -1(~59~71 Under low impact forces, such relative movement is undersirable since it will result in considerable changes ~ Sa -.,~ .
lOS9~71 in train len~3th ~nd at~en~ant prob]ems.
The valvc 43, however, preculdcs any flow thro-Jgh thc orifice ur~enin(~ 4] by hlocking t:he passagc 44 until a predetcrmined force is applied. When this predetermined force is reached, the pressure acting through the passage 44 on the valve memher 47 will cause its peripheral edge 48 to deflect away from the main piston 23 as shown in Figure 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 (~igure 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 vàlve 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 (Figure 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.
This invelltion relates to a cushioning unit and more particularly to a cushioning unit adapted for use at the ends of railway cars.
This is a division of copending Canadian Patent Application Serial Number 206,788, filed August 12, 1974.
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 differe~t 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 stroXe 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.
An 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.
According to the present invention there is provided an end of car cushioning unit adapted to be lQS90~1 interposed between a coupler and a car frame of a railway car for damping shock forces, the cushioning unit including a cylinder and a piston received within the cylinder, the piston and cylinder defining a chamber adapted to receive a li~uid and a gas under pressure acting on the contained liquid for exerting a restoring force on the cushioning unit.
Primary metering means is in communication with the chamber for permitting flow therethrough at a restricted rate upon relative movement of the piston and the cylinder. Means are io provided precluding the flow through the primary metering means until a predetermined force is applied to the cushioning unit. A bleed valve bypasses the means for precluding flow through the primary metering means for permitting a restricted rate of flow of the liquid.
Figure 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.
Figure 2 is an enlarged view showing the metering device of the cushioning unit as it appears under buff forces.
Figure 3 is an enlarged view, in part similar to Figure 2, showing the device as it appears when it lC~S9~71 experiences dr~ft forces.
Figure 1 illustrates an end of car cusllioning 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 underframe 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 i'lustrated installation will be describedj 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 pluq 17. The cylinder 16 defines a cylindrical bore 18 closed at one end by the cylinder head lS 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 assembl~ 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 antifriction 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 t0 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 sea; assembly 32 carried by the closure plug 17 supports and seal~ngly 1059C~7~
engac3cs the pj.C;ton rod 2~.
The piston rod 2~ has affixed to its outer end a draft collar 33 that is trapped in a draft lug asscmbly, ind.icated by the rcference numeral 34 that is fixed in any suitable manner to the ùnderframe 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 underframe 13. That is, the piston assembly 21 is held against any substantial movement relative to the underframe structure 13.
The cylinder head 15 is formed at its outer end with a socket 35 that receives the coupier 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 fixedcto the underframe 13 and is abuttingly engaged.by the cylinder head 15 when the cushioning unit 11 is in its fully extended draft position (Figure 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 aligned 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 presponsive valve assembly, indicated generally by the reference numberal 43 and 1059(~71 shown in most detail in Figures 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 sprlng valve member 47. In the nonflow condition the outer peripheral edge 48 of the valve member 47 sealingly engages the main piston 23. An opposite peripheral edge 49 sealingly engages 10. 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 a liquid in the form'of a 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 Figure 1. For a reason which will become 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, Figure 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 pres-sure in the chamber 19 would result in such relative movement.
~k ' ~r ~ - 5 -1(~59~71 Under low impact forces, such relative movement is undersirable since it will result in considerable changes ~ Sa -.,~ .
lOS9~71 in train len~3th ~nd at~en~ant prob]ems.
The valvc 43, however, preculdcs any flow thro-Jgh thc orifice ur~enin(~ 4] by hlocking t:he passagc 44 until a predetcrmined force is applied. When this predetermined force is reached, the pressure acting through the passage 44 on the valve memher 47 will cause its peripheral edge 48 to deflect away from the main piston 23 as shown in Figure 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 (~igure 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 vàlve 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 (Figure 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.
Claims
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
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 liquid and a gas under pressure acting on the contained liquid for exerting a restoring force on said cushioning unit, primary metering means in communication with said chamber for permitting flow therethrough at a restricted rate upon relative movement of said piston and said cylinder, means for precluding said flow 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 liquid.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA304,467A CA1059071A (en) | 1973-08-13 | 1978-05-31 | End of car cushioning unit |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US388330A US3929232A (en) | 1973-08-13 | 1973-08-13 | End of car cushioning unit |
| CA206,788A CA1036985A (en) | 1973-08-13 | 1974-08-12 | End of car cushioning unit |
| CA304,467A CA1059071A (en) | 1973-08-13 | 1978-05-31 | End of car cushioning unit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1059071A true CA1059071A (en) | 1979-07-24 |
Family
ID=27163572
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA304,467A Expired CA1059071A (en) | 1973-08-13 | 1978-05-31 | End of car cushioning unit |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1059071A (en) |
-
1978
- 1978-05-31 CA CA304,467A patent/CA1059071A/en not_active Expired
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