US3515286A

US3515286A - Railway car buff and draft force cushioning device

Info

Publication number: US3515286A
Application number: US743524A
Authority: US
Inventors: Richard Gordon Powell
Original assignee: ACF Industries Inc
Current assignee: Cooper Industries LLC
Priority date: 1968-07-09
Filing date: 1968-07-09
Publication date: 1970-06-02
Anticipated expiration: 1987-06-02
Also published as: NL6910501A; ES369293A1; GB1270556A; NL140464B; BE735878A; FR2012615A1; AT305364B; DE1934482A1; CH493357A

Description

R. G. POWELL 3,515,286

RAILWAY CAR BUFF AND DRAFT FORCE CUSHIONING DEVICE June 2, 1970 Filed July 9, 1968 .3 Sheets-Sheet 1 (REID FIG.

INVENTOR.

RIC hard Gordon 5006 U FIG. 2 BY R. G. POWELL 3,515,286 RAILWAY CAR BUFF AND DRAFT FORCE CUSHIONING DEVICE June 2, 1970 3 Sheets-Sheet 2 Filed July 9. 1968 INV/"TNTUR. Richard Gordon aws A GENT RAILWAY CAR BUFF AND DRAFT FORCE CUSHIONING DEVICE G. POWELL 3 Sheets-Sheet :3

Filed July 9, 1968 I N VFNTOR, IC hor-l/ Cor do i m @E United States Patent US. Cl. 213-8 13 Claims ABSTRACT OF THE DISCLOSURE A cushioned railway car structure including an underframe having a longitudinal center sill. A self contained pneumatic spring type end-of-car cushioning unit is disposed within the center sill and comprises an inner cylinder disposed in relatively immovable relation with the car structure and telescopically received by anouter cylinder. The outer cylinder is directly connected to the coupler structure of the railway car and is disposed in movable relation to the car structure. The cushioning unit structure and the car structure are so interrelated that buff forces on the car coupler below a predetermined force magnitude are transmitted in a positively aligned manner through the outer cylinder and the inner cylinder to the car structure and buff forces above a predetermined force magnitude are transmitted directly through the outer cylinder to the railway car structure. The interrelated structure between the cushioning and the center sill of the railway car also effectively allows the application of cushioned draft forces to the center sill during slack run out in addition to transmitting draft forces directly into the center sill in the normal or fully extended condition of the cushioning unit.

BACKGROUND OF THE INVENTION The present invention is particularly directed to cushioning systems or shock absorbing systems for railway cars in which the metering of a fluid is employed as an energy dissipative device. The majority of cushioning systems used for end-of-car cushioning employ the principle of hydraulic fluid metering to dissipate energy when either buff or draft forces are applied to the cushioning units. This method of energy dissipation is velocity sensitive in that the amount of energy dissipation is directly proportional to the velocity of fluid flowing through the metering orifice of the cushioning device. The cushioning unit is therefore capable of being collapsed by high velocity impacts which may occur when cars are coupled or it may be collapsed by low velocity forces such as may occur during a downgrade braking condition.

It is a primary object of this invention therefore to provire a novel hydraulic end-of-car cushioning device including telescoping inner and outer cylinders which is effective to transmit buif forces below a predetermined force magnitude through both the outer and inner cylinders to the railway car structure and to transmit buff forces above a predetermined force magnitude directly through the outer cylinder structure and into the railway car structure for the purpose of protecting the inner cylinder structure from excessive deflection and for achieving optimum distribution of forces.

A further object of this invention involves the pr0- vision of a novel hydraulic cushioning system for railway cars which is capable of transmitting draft forces through the hydraulic cushioning unit to the railway car structure during slack run out and which is capable of transmitting draft forces directly into the car structure without transmitting draft forces through the cushioning unit when the 3,515,286 Patented June 2, 1970 cushioning unit is in its neutral or fully extended position.

An even further object of this invention contemplates the provision of a novel hydraulic cushioning system which maintains positive alignment of the cushioning unit within the railway car or structure and which effectively provides positive alignment of axial buif forces to prevent excessive deflection of the inner cylinder of the cushioning unit structure.

Among the several objects of this invention it is contemplated the provision of a novel hydraulic cushioning system for railway car structures which employs a hydraulic cushioning unit having a floating piston therein which separates a compressed medium such as nitrogen gas from an incompressible medium such as hydraulic fluid and which is so arranged relative to the car structure as to achieve direction of fluid movement and floating piston movement which eliminates the occurrence of unusual accelerations of the piston or fluid.

Another object of my invention involves the provision of novel interrelated railway car and hydraulic cushioning unit structure which is effective to transmit only cushioned mechanical shocks to the inner cylinder structure to reduce the possibility of damaging the inner cylinder structure of the cushioning unit by excessive mechanical shocks.

It is an even further object of this invention to provide a novel hydraulic cushioning system for railway car structures which is simple in construction, reliable in use and low in cost.

Briefly, the invention involves the provision of rear stop structures which are aflixed within the center sill of a railway car at each extremity thereof and which define a buff cushion stop to transmit low magnitude buff forces from a cushioning unit to the under-frame of the railway car. The rear stop structure also includes a draft cushion stop which is effective to transmit draft forces from the cushioning unit to the center sill structure during slack run out of the cushioning unit from its compressed position toward its fully extended or neutral position. The rear stop structure is also provided with an over solid stop surface which is effective to transmit high magnitude buff forces directly from the outer cylinder structure of the hydraulic cushioning unit to the center sill structure without passing these excessive forces to the inner cylinder structure of the hydraulic cushioning unit. This feature effectively prevents damage to the cushioning unit which might occur if the bulf forces applied to the inner cylinder are suflicient to cause excessive deflection thereof. The center sill structure is also provided with draft stop lugs which are located. immediately adjacent the extremities of the center sill and which are engaged by stop surfaces formed on an outer cylinder end cap structure of the cushioning unit in the neutral or extended position of the cushioning unit. This structure is so arranged that draft forces applied to the cushioning unit in the normally extended position thereof will be trans mitted directly from the outer cylinder end cap structure of the cushioning unit into the center sill structure through the draft stop lugs.

The hydraulic cushioning unit of this invention is provided with a buff alignment plate which is disposed between the buff cushion stop on the rear stop structure and the inner cylinder end cap. The buff alignment plate is so related to the inner cylinder end cap that buff forces are transmitted throuugh the inner cylinder structure in positively aligned condition thereby preventing excessive deflection of the inner cylinder. The transmission of positively aligned forces through the cushioning unit structure and the capability of a cushioning unit to transmit high magnitude forces directly through the outer cylinder structure and into the center sill structure effectively results in protection of the cushiOning unit structure from damage by high magnitude shock forces.

Other and further ebjects of this invention will become obvious upon an understanding of the illustrated embodiment about to be described or will be indicated in the appended claims. Various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice. A preferred embodiment of the invention has been chosen for the purpose of illustration and description and is shown in the accompanying drawings forming a part of the specification wherein:

FIG. 1 is a side elevational view of a pair of railway box cars which are connected by means of couplers of the E type connected to hydraulic cushioning systems constructed in accordance with the instant invention.

FIG. 2 is an exploded view in perspective illustrating one end of the center sill of a railway flat car which normally utilizes F type couplers and the associated hydraulic cushioning unit as constructed in accordance with this invention. Only the type F c upler embodiment of this invention is illustrated in the remaining figures. The type B coupler version differs only in the configuration of the outer cylinder end cap.

FIG. 3 is a partial sectional view of the hydraulic cushioning unit of FIG. 2 illustrating the internal structure thereof in detail and Showing the relationship between the inner cylinder end cap and the buff alignment plate structure of the cushioning unit.

FIG. 4 is a fragmentary plan view of the center sill structure of a railway car illustrating the hydraulic cushioning unit of FIG. 3 in its neutral or fully extended position within the center sill structure.

FIG. 5 is a partial sectional view of the center sill structure of a railway car illustrating the position of the hydraulic cushioning unit during the application of buff forces.

FIG. 6 is a partial sectional view of the center sill structure of a railway car illustrating the fully compressed position of the hydraulic cushioning unit upon the application of buff forces above a predetermined force magnitude.

FIG. 7 is a partial sectional view of the center sill structure of a railway car illustrating the position of the hydraulic cushioning unit of this invention during the application of draft forces from the compressed condition thereof.

Referring now to the drawings for a better understanding of this invention, railway cars 10- and 11 illustrated in FIG. 1 are interconnected by means of couplers 12. Assuming that each of the railway cars of FIG. 1 is of the cushioned underframed type and end-of-car cushioning system will be arranged inwardly of each of the couplers 12. The underframe of each of the railway cars 10 and 11 will include a longitudinally disposed fixed center sill generally designated 14 within which the cushioning system is arranged. The center sill 14 is a generally hat shaped sill having a horizontal top web 15, vertically disposed side webs 16 and horizontally disposed bottom flanges 17. On cars equipped with type F couplers, the center sill construction is provided with a bell mouth at each extremity thereof which is defined by diverging portions of the side webs 16 creating a flared portion which receives the shank portion 19 of the coupler member 12 and allows articulation of the coupler member relative to the center sill construction. The bell mouth portion 18 of the center sill structure is also provided with an arcuate coupler carrier structure 20 to provide for support of the coupler 12 in a substantially horizontal position. The upper surface of the coupler carrier 20 defines a wear surface which is engaged by the shank portion 19 of the coupler.

A rear stop casting 22 is disposed within the center sill 14 and is welded to the side webs 16 and the top web 15 of the center sill. The rear stop casting 22 is provided with a transverse slot 24 which defines a buff cushion stop surface 26 and a draft cushion stop surface 28. An over solid stop surface 30 is defined by the front portion of the rear stop casting. A pair of

draft stop lugs

32 and 34 are fixed to the side Webs 16 of the center sill structure by welding or the like and are engaged by the outer cylinder end cap structure of the hydraulic cushioning unit as described hereinbelow.

An air spring type hydraulic cushioning unit illustrated generally at 36 in FIGS. 2 and 3 comprises telescopically related inner and outer cylinders 38- and 40 respectively which cooperate to define a high pressure hydraulic chamber 42, a low pressure hydraulic fluid chamber 44 and a draft cushioning chamber 46. A floating piston 48 is disposed within the inner cylinder 38 in sealed relation therewith and serves to separate the low pressure hydraulic chamber 44 from a compressible fluid chamber 50 defined between the floating piston 48 and an inner cylinder end cap 52 threadedly received at the free extremity of the inner cylinder 38. The inner cylinder end cap 52 is provided with a fluid passage 54 the outer extremity of which is closed by an inflation valve 56, which serves as a check valve and secondary seal. A seal plug 58 provides the primary seal for fluid chamber 50 in addition to protecting the inflation valve 56. A compressible fluid such as nitrogen gas or the like is introduced through the inflation valve 56 and the passage 54 into the compressible fluid chamber 50 of the inner cylinder. This compressible medium will apply a force on the floating piston 48 which biases the piston toward the inner extremity of the inner cylinder thereby maintaining hydraulic fluid within the

chambers

42, 44, and 46, under a preload pressure at all times. The preload pressure within the compressible fluid chamber 50 serves as a centering force which biases the cushioning unit structure from its compressed position as illustrated in FIG. 3 to the extended or neutral position thereof as illustrated in FIG. 4.

The outer cylinder 40 is closed at one extremity thereof by a packing adapter 60 which is provided with an inner extension 62 defining an abutment shoulder 64. The extension '62 of the packing adapter 60 is received within the outer cylinder 40 and is maintained in sealed relation with the outer cylinder by a sealing ring 66. A sealed relation between the inner cylinder 38 and the packing adapter 60 is maintained by a packing assembly 68 which is carried by the packing adapter. The packing assembly 68 includes a bearing member 69 which provides adequate bearing contact with the outer surface of the inner cylinder 38.

The other extremity of the outer cylinder is closed by means of an outer cylinder end cap 70 which is provided with an axial extending portion 72 defining an annular abutment 74. The axial extension 72 is maintained in sealed relation with the inner surface of the outer cylinder by means of a sealing ring 76.

The packing adapter 60 and the outer cylinder end cap 70 are maintained in assembly with the outer cylinder 40 by means of a series of tie bolts 78 which serve to maintain the annular shoulders 64 and 74 of the packing adapter and outer cylinder end cap respectively in intimate engagement with the extremities of the outer cylinder 40. The tie bolts 78 extend through apertures in the packing gland adapter 60 and are provided with a threaded portion 80 which is received within threaded apertures formed in the outer cylinder end cap 70. The tie bolts 78 are provided with a head portion 82 which is locked against rotation relative to the packing gland adapter 60 by means of locking members 84. The tie bolts are prestressed in tension to such an extent that maximum draft loads applied thereto will not lengthen the tie bolts sufficiently to develop a loose condition between the outer cylinder 40 the packing gland adapter 60 and the outer cylinder end of cap 70. The outer cylinder end cap 70 is provided with an axially disposed circular flange 85 which receives one extremity of a metering pin 86 in a close fitting relation therein. The metering pin 86 is maintained in assembly with the circular flange 85 by a series of bolts 88 which extend through a circular retainer member 90 and are received within threaded apertures formed within the circular flange 85. The retainer member 90 bears against a circular shoulder 92 formed on the metering pin 86 and biases the shoulder 92 into positive engagement with the circular flange.

The metering pin 86 is tapered throughout its length and extends through a metering aperture 94 formed centrally of an orifice plate structure 96. The orifice plate 96 is provided with a circular skirt portion 98 which is internally threaded and which threadedly receives an externally threaded portion of the inner cylinder 38.

A bearing member 100 is interposed between the inner cylindrical surface 102 of the outer cylinder 40 and a cylindrical surface 103 formed on the orifice plate structure 96. The bearing 100 is retained in assembly with the orifice plate structure 96 by an annular shoulder 104 formed at the extremity of the annular skirt 98 and by a retainer ring 106 which is received within an annular groove formed in the orifice plate.

The variable volume draft cushioning chamber 46 is defined by an annular space between the inner periphery 102. of the outer cylinder 40 and the outer periphery of the inner cylinder 38. Fluid communication between the draft cushioning chamber 46 and the inner or low pressure hydraulic chamber 44 is maintained by plurality of ports 108 formed in the inner cylinder 38. A draft cushioning valve 110 is disposed within the draft cushioning chamber 46 about the inner cylinder 38 and cooperates with the ports 108 to allow relatively free flow of hydraulic fluid from the chamber 44 to the chamber 46 during compression of the sushioning unit from the neutral position of FIG. 4 to the compressed position illustrated in FIG. 3. Upon extension of the cushioning unit from the FIG. 3 position toward the FIG. 4 position, the draft cushion valve 110 will be forced by the hydraulic fluid into engagement with the circular skirt portion 98 of the orifice plate 96 thereby causing the draft cushion valve to substantially restrict the ports 108. Hydraulic fluid will be metered through the restricted ports 108 upon extension of the cushioning unit resulting in considerable dissipation of energy. It is evident therefore that upon extension of the cushioning unit from the FIG. 3 position to the FIG. 4 position under draft loads considerable energy is dissipated thereby providing protection to the railway car structure and its lading. The draft cushion valve 110 also prevents excessively rapid recentering of the cushioning unit, generally referred to as slamming, subsequent to the application of buff forces which might otherwise result in rebound accelerations in the car and lading.

'In order to prevent confusion, only so much of the construction of the draft cushion valve as is essential to an understanding of this invention is described herein. For a more detailed description and explanation of the draft cushion valve reference may be had to US. Pat. No. 3,378,149 which sets forth the structure and function of the draft cushion valve 110 in detail.

The inner cylinder end cap 52 is provided with a convex surface 112 which mates with a concave surface 114 formed on a generally rectangular buff force alignment plate 116. The mating concave and convex surfaces effectively maintain maximum surface contact between the inner cylinder end cap and the buff force alignment plate 116 and allow the planar surface 117 to achieve full surface contact with the butf cushion stop surface 26 even though the cushioning unit 36 might be slightly misaligned within the center sill. This feature effectively compensates for wide manufacturing tolerances, assures optimum surface contact and assures positive alignment of forces transmitted from the cushioning unit structure to the center sill structure. The hydraulic cushioning unit 36 is disposed within the center sill structure 14 in such a manner that a rectangular portion of the inner cylinder end cap and the buff force alignment plate 116 are received within the substantially rectangular space 24 defined in the rear stop casting 22. The outer cylinder end cap 70 is provided with a pair of

abutment shoulders

118 and 120 as illustrated in FIGS. 2 and 4 particularly, which, in the extended position of the cushioning unit, engage abutment stop shoulders 122 and 124 formed on the draft stop lugs 32 and 34 respectively. The cushioning unit 36 is supported within the center sill by a support plate 126 connected to the bottom flanges 17 of the center sill by means of bolts or the like. The shank portion 19 of the coupler 12 extends through the bell mouth portion 18 of the center sill and is pivotally connected to a bifurcated portion 128 of the outer cylinder end cap 70 by means of a pivot pin 130 extending through aligned

bores

132 and 134 in the outer cylinder end cap and extending through a bore 136 formed in the shank 19 of the coupler. The pivot pin 130 is supported by a wear plate support 138 which is fixed to the support plate 126 and which is provided with a wear surface 140 which extends through an aperture 142 in the support plate. The shank 19 of the coupler 12 may be disconnected from the outer cylinder end cap structure 70 of the hydraulic cushioning unit 36 by removing the pivot pin support plate 138 thereby allowing the pivot pin 130 to be removed through the aperture 142 in the support plate 126. The hydraulic cushioning unit 136 is removed from its position within the center sill 14 by unbolting the support plate 126 and releasing a substantial amount of the fluid pressure within the compressible fluid chamber 50 by opening the inflation valve 56. Deflation of the compressible fluid chamber 50 allows the cushioning unit to collapse slightly thereby reducing the friction between the

shoulders

118 and 120 of the cushion unit and the draft stop lugs 32 and 34 of the center sill and also reducing the friction between the buff cushion stop surface 26 and the planar surface 117 of the buff alignment plate 116.

Insertion of the cushioning unit 36 into the center sill 16 is accomplished while the cushioning unit is in a deflated condition and resting on the cushion support plate 126. After positioning in the center sill, the support plate 126 is bolted to the lower flanges of the still 17. Subsequent to insertion of the cushioning unit, the compressible fluid chamber 50 is inflated by connecting suitable inflation structure to the inflation valve 56 and forcing a compressible fluid such as nitrogen gas into the chamber 50. When this is done, the cushioning unit will extend to the fully extended condition causing the

shoulders

118 and 120 of the outer cylinder end cap 70 to engage the draft stop lugs 32 and 34 and also causing the buff force alignment plate 116 to bear upon the buff cushion stop surface 26 of the rear stop casting 22. After the cushioning unit has been installed, the coupler 12 is connected to the cushioning unit by inserting the shank portion 19 of the coupler into the bifurcated portion 128 of the outer cylinder end cap 70 thereby aligning the aperture 136 of the coupler with the

pivot apertures

132 and 134 of the outer cylinder end cap. The pivot pin 130 is then inserted through the aligned

apertures

132, 134, and 136 thereby positively connecting the coupler to the outer cylinder end cap structure of the cushioning unit. The pivot pin support member 138 is then connected to the support plate 126 by means of bolts thereby presenting the wear plate 140 for support of the pivot pin 130.

With reference now to FIGS. 5, 6, and 7 which illustrate the structure of the center sill and the associated hydraulic cushioning unit 36 in various operational positions thereof, attention is directed to FIG. 5 which illustrates the hydraulic cushioning unit 36 as it appears during application of buff forces. Buff forces, which are applied to the coupler 12, will act through the outer cylinder end cap structure 70 of the hydraulic cushioning unit 36 to cause compression of the cushioning unit. When this occurs, hydraulic fluid from the outer or high pressure bydraulic chamber 42 is forced through the metering orifice 94 of the cushioning unit under control of the metering pin 86 which varies the effective size of the metering orifice as the cushioning unit is collapsed and extended. The hydraulic fluid forced through the metering orifice 94 will enter the low pressure hydraulic chamber 44 and will force the floating piston 48 toward the inner cylinder end cap 52 thereby decreasing the volume and increasing the pressure of the compressible fluid within the compressible fluid chamber 50. As the hydraulic cushioning unit is compressed, the variable volume draft cushioning chamber will increase in volume thereby allowing hydraulic fluid to flow through the ports 108 past the draft cushioning valve 110 and into the draft cushioning chamber 46.

Buff forces which are applied to the hydraulic cushioning unit 36 will pass from the outer cylinder end cap 70, through the hydraulic fluid and orifice plate to the inner cylinder 38. Bufl forces from the inner cylinder 38 will in turn be transmitted through the end cap structure 52, the buff force alignment plate 116 and into the center sill 14 through the rear stop casting 22. Since the planar surface 117 of the buff force alignment plate 116 is capable, through the interrelated concave and

convex surfaces

114 and 112 respectively, of achieving bearing with the rear stop casting through its entire surface area it is quite evident that forces transmitted through the rear stop casting will be evenly distributed thereby preventing the develop-rnent of critical force levels at any specific location.

Buff forces up to a predetermined force magnitude will be transmitted through the hydraulic cushioning unit and into the rear stop casting through the buff cushion surface 26. In the event the buff force is greater than the predetermined force magnitude or in the event that the application of buff forces is of considerable duration such as would occur during a downgrade locomotive braking condition, the hydraulic cushioning units, being velocity sensitive, will collapse to the position illustrated in FIG. 6 and the shoulder 31 on the packing gland adapter 60 will engage the over solid stop surface thereby causing further buff forces to be applied from the coupler through the outer cylinder end cap structure 70 and through the outer cylinder 36 and the packing gland adapter 60 directly into the front portion of the rear stop casting 22. This feature protects the hydraulic cushioning unit by allowing the transmission of high magnitude buff forces through the large outer cylinder structure and thereby prevents, unnecessary deflection of the inner cylinder 38 which might otherwise result in damage or excessive wear. This feature also enhances further protection of the cushioning unit structure and of the center sill and rear stop casting structure by developing greater distribution of the buff forces applied to the rear stop casting structure. With the cushioning unit structure in the FIG. 6 position thereof, a predetermined portion of the buff forces will continue to be exerted through the inner cylinder structure and into the rear stop casting through the buff cushion stop surface 26 thereby transmitting these forces through the rear portion of the rear stop casting. The remainder of the buff forces will be transmitted through the outer cylinder structure of the hydraulic cushioning unit and into the front portion of a rear stop casting. Greater distribution of buff forces achieved through the unique cooperation between the hydraulic cushioning unit and the rear stop casting structure allows the provision of more lightweight construction of the rear stop casting structure than is ordinarily practical and effectively promotes the manufacture of an inexpensive and competitive car cushioning structure without detracting from the utility thereof.

After the hydraulic cushioning unit 36 has become compressed, either by the application of buff forces or upon the occurrence of slack run in during a downgrade locomotive braking condition or the like, the hydraulic cushioning unit may be returned to its neutral or fully extended position as illustrated in FIG. 4 either by internal recentering forces developed by the compressible fluid or upon the application of draft forces to the coupler structure 12. The hydraulic cushioning unit is so designed that,

upon dissipation of buff forces applied to the upper structure, the compressible fluid within the compressible fluid chamber 50 exerts an equal pressure in

chambers

42, 44, and 46. Since the effective pressure area in chamber 42 is larger than the combined areas of

chambers

44 and 46, the inner cylinder is biased toward the extended or neutral position. The draft cushion valve structure will move downstream into engagement with the skirt portion 98 of the metering orifice plate 96 thereby resulting in metering of the hydraulic fluid from the draft cushioning chamber 46 into the inner hydraulic fluid chamber 44. This feature prevents excessively rapid extension of the cushioning unit 36 from the compressed condition thereof as discussed above.

Upon the application of draft forces to the hydraulic cushioning unit when the cushioning unit is in its compressed condition as illustrated in FIG. 7, the draft cushion valve 110 effectively meters hydraulic fluid from the draft cushioning chamber 46 and causes the dissipation of considerable energy in draft.

Draft forces which are applied While the cushioning unit was disposed in its neutral or fully extended position as illustrated in FIG. 4 are transmitting directly into the draft stop lugs 32 and 34 through the outer cylinder end cap structure 70 of the cushioning unit.

The unique construction of the center sill structure and the hydraulic cushioning unit structure of this invention effectively promotes the application of buff forces at a location inwardly from the extreme end of the center sill structure rather than at the extremity of the center sill structure as is ordinarily the case. This feature affords protection for the center sill structure to prevent excessive deflection thereof due to the application of buff forces near the bolster structure of the railway car.

Another advantage gained through the unique relationship established between the hydraulic cushioning unit and center sill structure involves the interposition of a fluid column between that portion of the cushioning unit structure which receives the initial buff force shock and the inner cylinder structure. Shock forces applied to the outer cylinder end cap structure must traverse this fluid column before entering the inner cylinder structure. This feature effectively mitigates the mechanical shock applied to the inner cylinder thereby serving to enhance the useful life of the cushioning unit.

The construction of the cushioning unit and its unique relation with the outer sill structure also causes draft cushioning forces to be resisted by the inner cylinder and to be transmitted through the fluid column into the packing adapter portion of the outer cylinder structure. The draft cushioning forces are then transmitted through the tie bolts, through the outer cylinder end cap and to the coupler. The fluid column therefore effectively mitigates the mechanical shocks applied to the cushioning unit during the draft cushioning operation.

An important aspect of this application concerns the relative positioning of the hydraulic cushioning unit and the center sill structure as compared to other methods of cushioning unit positioning. Positioning of the hydraulic cushioning unit structure of this invention with the outer cylinder disposed at the extremity of the center sill structure and directly connected to the coupler 12 eliminates unusual acceleration of the piston or fluid within the hydraulic cushioning unit because the direction of fluid movement and the direction of movement of the floating piston member coincide with the direction of impact forces.

The outer cylinder end cap structure, the packing adapter structure and the inner cylinder end cap structure are of generally rectangular configuration and effectively cooperate with the generally rectangular inner portion of the center sill structure to maintain positive alignment of the cushioning unit throughout its operational sequence. It is also important to note that the hydraulic cushioning unit is substantially symmetrical in shape and dimension thereby allowing the cushioning unit structure to be inverted in the event that excessive wear should develop on one side thereof or in the event the center sill should become worn excessively on one side thereof.

It will be evident from the foregoing that I have provided a unique hydraulic cushioning unit and railway car center sill structure which cooperate to achieve eflective distribution of bufl and draft forces which are applied thereto in order to prevent damage to either the cushioning unit structure or the center sill structure due to excessive load development. This feature is accomplished by optimum construction and positioning of the hydraulic cushioning unit within the center sill structure of the railway car and by the provision of a multi-purpose rear stop casting structure aflixed to the center sill structure. The hydraulic cushioning unit and the rear stop casting structure are so interrelated that buff forces below a predetermined force magnitude are transmitted through the fluid and inner cylinder of the hydraulic cushioning unit and into a buff cushion stop provided at the rearmost portion of the rear stop casting. The cushioning unit structure is effectively protected from damage during the application of buff forces above a predetermined magnitude since the unique construction of this invention allows transmission of buff forces directly through the outer cylinder of the hydraulic cushioning unit and into the frontmost portion or over solid stop of the rear stop casting and into the center sill structure. This feature effectively prevents excessive deflection of the inner cylinder which might otherwise result in damage to the inner cylinder of the cushioning unit. Upon the application of draft forces to the hydraulic cushioning unit in the compressed condition thereof, the structure of the cushioning unit center sill is effective to transmit cushioned draft forces to the rear stop casting portion of the center sill. Draft cushioning forces which are applied to the cushioning unit are transmitted through the fixed inner cylinder through the hydraulic fluid and into the packing adapter structure which in turn transmits the draft cushioning forces through the tie bolts and into the coupler structure. Draft forces which are applied to the hydraulic cushioning unit in the extended or neutral position thereof are transmitted directly through the outer cylinder end cap structure of the cushioning unit and into the center sill structure through a pair of draft stop lugs. The length and structural shape of the outer cylinder portion of the hydraulic cushioning unit effectively provide sufficient guidance Within the center sill structure and also provides sufficient resistance to deflection to prevent damage to the cushioning unit upon the application of severe impact loads. The inner cylinder structure of the cushioning unit is stationary with respect to the center sill so that the inflation valve structure is properly positioned for ready access at all times. The inner cylinder transmits cushioning forces only after they have been imparted through the hydraulic fluid rather than being directly connected to car coupler structures as is frequently the case. Therefore, it is seen that this invention is one well adapted to attain all of the objects hereinabove set forth together with other advantages which will become obvious and apparent from the description of the apparatus itself.

It will be understood that certain combinations and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims. As many possible embodiments may be made of the invention without departing from the spirit or scope thereof it is to be understood that all matters hereinabove set forth and as shown in the accompanying drawings are to be interpreted as illustrative and not in a limiting sense.

I claim:

1. A railway car having an underframe including a longitudinal center sill, a unitary structure carried by said underframe and defining a buff cushion force stop means, a rear draft cushion force stop means and an over solid buff force stop means, means on said underframe defining front draft force stop means, at least one hydraulic cushioning unit carried by said underframe adjacent the extremity thereof, said cushioning unit having an inner cylinder and an outer cylinder, said outer cylinder receiving the inner cylinder in telescoping relation and cooperating with said inner cylinder to define a plurality of hydraulic chambers and a compressible fluid chamber, hydraulic fluid disposed within said hydraulic chambers and being maintained under a preload pressure by a compressible fluid disposed within said compressible fluid chamber, a railway car coupler being connected to the outer extremity of said cushioning unit, said cushioning unit in the neutral position thereof being maintained in engagement with said buff cushion force stop means and said front draft force stop means, upon compression of said cushioning unit buff forces below a predetermined magnitude being transmitted from said coupler through said outer and inner cylinders and into said center sill through said rear buff cushion stop means and buff forces above a predetermined force magnitude being transmitted from said coupler through said outer cylinder and into said center sill through said over solid buff force stop means, upon the application of draft forces to said cushioning unit in the compressed condition thereof draft cushioning forces being transmitted through said cushioning unit and into said center sill through said rear draft cushion stop means, draft forces applied to said coupler in the neutral position thereof being transmitted directly to said center sill without passing through said inner or outer cylinders.

2. A railway car as set forth in claim 1, said unitary structure comprising a rear stop :structure fixed within said center sill and having a buff cushion surface, a draft cushion stop surface and an over solid buflf force stop surface, alignment means disposed. in contact with said cushioning unit and being disposed for full surface engagement with said buff cushion surface, said alignment means transmitting aligned buff forces to said cushioning unit even though said cushioning unit may be disposed in slightly misaligned relation with said buff cushion surface.

3. A railway car as set forth in claim 1 said inner cylinder of said cushioning unit being disposed in relatively immovable relation with respect to said underframe, said outer cylinder means being movable with respect to said center sill, said outer cylinder means being directly connected to said coupler of said railway car.

4. A railway car as set forth in claim 1 said outer cylinder structure comprising a cylindrical member, an outer cylinder end cap closing one extremity of said outer cylinder, a packing gland adapter being received at the other extremity of said cylinder, a plurality of tie bolts retaining said outer cylinder end cap and said packing gland adapter in assembly with said outer cylinder, said outer cylinder end cap being directly connected to said coupler.

5. A railway car as set forth in claim 1, a fluid column defined between said inner and outer cylinder structures, mechanical shock forces transmitted between said inner and outer cylinder structures being conducted through said fluid column thereby mitigating said shock forces and protecting said inner cylinder against excessive deflection.

6. A. railway car having an underframe including a longitudinal center sill and a coupler, cushioning unit support structure being positioned at least one extremity of said center sill, a rear stop structure fixed Within said center sill at a position remote from the extremity thereof, said rear stop structure defining a bufl cushioning stop adjacent the rear portion of said rear stop structure, an over solid stop at the front portion of said rear stop structure and a draft chusion stop intermediate the extremities of said rear stop structure, draft stop lugs fixed within said center sill adjacent the extremity thereof, a telescoping hydraulic cushioning unit disposed within said center sill and being movable between neutral and collapsed positions, said hydraulic cushioning unit having an inner cylinder structure disposed in relatively immovable relation with respect to said center sill and an outer cylinder structure disposed in movable relation with said center sill, said inner cylinder transmitting buff forces below a predetermined magnitude to said buff cushioning stop and transmitting draft cushioned forces applied while said unit is in a compressed condition to said draft cushion stop, said outer cylinder contacting said over-solid stop in the fully compressed condition of said cushioning unit and transmitting buff forces above a predetermined magnitude through said outer cylinder and into said over-solid stop, one extremity of said outer cylinder structure being directly connected'to the coupler of said railway car and in the neutral condition of said cushioning unit transmitting draft forces applied by said coupler directly to said draft stop lugs.

7. A railway car as set forth in claim 6, said hydraulic cushioning unit comprising an inner cylinder structure disposed in relatively immovable relation with said center sill, an outer cylinder structure in telescoping relation and cooperating with said inner cylinder structure to define variable volume buff force cushioning hydraulic chamber means and draft force cushioning chamber means, said cushioning unit having means defining a compressible fluid chamber means in which is disposed a compressible fluid maintained under a predetermined minimum pressure, said compressible fluid maintaining said hydraulic fluid under pressure and normally maintaining said cushioning unit in the extended condition thereof.

8. A railway car as set forth in claim 6, said hydraulic cushioning unit comprising an inner cylinder structure disposed in substantially immovable relation with said center sill, an outer cylinder structure receiving said inner cylinder structure in telescoping relation therewith, means maintaining said cushioning unit in a normally extended condition and biasing said inner cylinder structure ito engagement with said buff cushioning stop and biasing said outer cylinder structure into engagement with said draft stop lugs.

9. A railway car as set forth in claim 8, said inner cylinder structure comprising an elongated cylinder, an outer cylinder end cap closing one extremity of said outer cylinder, a packing gland adapter disposed about said inner cylinder structure in sealed relation therewith and being disposed in sealed abutting relation with the other extremity of said outer cylinder, a plurality of tie bolts received by said outer cylinder end cap and by said packing gland adapter and serving to retain said outer cylinder end cap and said inner cylinder end cap in assembly with said outer cylinder, said outer cylinder end cap being directly connected to said coupler.

10. A railway car as set forth in claim 9, draft stop means defined on said outer cylinder end cap and being engageable with said draft stop lugs in the normally extended position of said hydraulic cushioning unit whereby draft forces applied to said coupler in the extended condition of said hydraulic cushioning unit will be transmitted directly to said center sill at a portion adjacent the extremity thereof.

11. A railway car as set forth in claim 8, said inner cylinder structure comprising an elongated cylinder member, a floating piston disposed in sealed relation within said elongated cylinder member and defining a compressible fluid chamber, an inner cylinder end cap closing one extremity of said inner cylinder, said means maintaining said cushioning unit in a normally extended condition comprising a pressurized fluid disposed within said pressurized fluid chamber and acting through said floating piston to maintain hydraulic fluid within said hydraulic chambers under pressure, said inner cylinder end cap having means for the introduction of a compressible fluid into said compressible fluid chamber.

12. A railway car as set forth in claim 11 said inner cylinder end cap having a draft shoulder defined thereon, said draft shoulder engaging said draft cushion stop upon the application of draft forces to said cushioning unit in the compressed condition thereof, an arcuate surface formed on said inner cylinder end cap, a buff force alignment plate disposed in assembly with said inner cylinder end cap and having an arcuate surface defined thereon and mating with said arcuate surface of said inner cylinder end cap, said buff force alignment plate having a generally planar surface thereon disposed in full surface contact with said buif force cushioning stop, said buff force alignment plate being operative to transmit buff forces in a positively aligned and evenly distributed manner into said rear stop structure.

13. A railway car having an underframe including a longitudinal center sill a unitary stop structure carried by said underframe and defining a buff cushion stop means a rear draft cushion force stop means and an over-solid buff force stop means, means on said underframe defining front draft force stop means, at least one compressible hydraulic cushioning unit means carried by said underframe adjacent the extremity thereof, said cushioning unit having an outer cylinder and an inner cylinder received by said outer cylinder in telescoping relation, in its neutral position said inner cylinder cushioning unit engaging said buff cushion stop means and said outer cylinder of said cushioning unit engaging said front draft force stop means, a railway car coupler being connected to said cushioning unit, upon compression of said cushioning unit buff forces below a predetermined force magnitude being transmitted through said inner and outer cylinders and into said buff cushion force stop means and buff forces above said predetermined force magnitude being transmitted only through said outer cylinder and into said underframe through said over-solid buff force stop means, upon draft extension of said cushioning unit means from the compressed condition thereof draft cushioned forces being trans mitted through said inner and outer cylinders and through said rear draft cushion stop means to said underframe, draft forces applied to said coupler in the neutral position of said cushioning unit being transmitted directly to said underframe without passing through said inner or outer cylinders.

References Cited UNITED STATES PATENTS Rollins 213-8 DRAYTON E. HOFFMAN, Primary Examiner U.S. Cl. X.R. 213-43