US3378149A

US3378149A - Railway car cushioning device

Info

Publication number: US3378149A
Application number: US540428A
Authority: US
Inventors: Richard G Powell
Original assignee: ACF Industries Inc
Current assignee: Joy Manufacturing Co
Priority date: 1966-02-14
Filing date: 1966-02-14
Publication date: 1968-04-16
Anticipated expiration: 1985-04-16

Description

April 16, 1968 R. s. POWELL RAILWAY CAR CUSHIONING' DEVICE 5 Sheets-Sheet 1 Filed Feb. 14, 1966 mum mww T a, KMWWKE \\L Q M nu ma INVENTOR.

A GENT 5 Sheets-Sheet 2 m Wm N A i E 1 w P l u| T I I I l V IiiW J J J N w I M 3,. 3:: i. H a Viifix-.. u A a I I f I1 I n m h K v a #N K W on AGENT April 16, 1968 R. G. POWELL RAILWAY CAR CUSHIONING DEVICE Filed Feb. 14, 1966 April 16, 1968 R. G. POWELL RAILWAY CAR CUSHIONING DEVICE 5 Sheets-Sheet 3 Filed Feb. 14, 1966 INVEN'I UR.

April 1968 R. G. POWELL 3,378,149

RAILWAY CAR CUSHIONING DEVICE Filed Feb. 14, 1966 5 Sheets-Sheet 4 fimfia/a Q Pan/e INVENTOR.

April 16, 1968 R. G. PQWELLV 5 Sheets5heet 5 Filed Feb. 14, -l966 United States Patent 3,378,149 RAlLWAY CAR CUSHIONING DEVICE Richard G. Powell, Houston, Tex., assignor to ACF Industries, Incorporated, New York, N.Y., a corporation of New Jersey Filed Feb. 14, 1966, Ser. No. 540,428 21 Claims. (Cl. 213-43) ABSTRACT OF THE DISCLOSURE A double acting hydraulic cushioning unit for railway cars which incorporate an auxiliary draft cushioning systern and comprises a pair of telescopically related bydraulic cylinders cooperating to define an auxiliary draft cushioning hydraulic chamber. The auxiliary draft cushioning chamber is provided with fluid metering means which is effective to change the energy dissipating characteristics of the auxiliary draft cushioning system responsive to fluid pressure conditions within the auxiliary draft cushioning chamber.

This invention relates to a cushioning structure for use in railway cars of the type commonly referred to as end-of-car cushioning, which are employed to eliminate or significantly reduce the damage to both the car and its lading during end to end impact and during normal train action. More specificially, the cushioning structure comprising this invention utilizes a hydraulic cushioning unit cooperatively with a resilient draft gear in both buff and draft operation to provide for the dissipation of substantial amounts of energy in either direction and from any position from full buff to full draft.

Herctofore, hydraulic units have been employed in end-of-car cushioning devices for the specific purpose of dissipating energy during an impact which results in compression or buff movement of the cushion. Similarly, resilient draft gears have been employed in conjunction with hydraulic units for the purpose of reducing buff forces during an impact. These devices, however, do not have the capability of dissipating energy when subjected to a draft force in particularly from the full positio Some units provide a small amount of snubbing n in draft primarily to reduce rebounding caused by the centering mechanism. Other units perform the function by utilizing the buff metering system in reverse during draft travel which is ineffective under most of draft movemer it is pointed out that the primary 'ilferenee in snubsystems for hydraulic cushioning units and hydraulic draft cushioning mechanisms resides in the ability of the cushioning unit to dissipate externally applied energy. Snub'c-iag systems are provided to restrict free extension of the cushioning unit after it has been compressed by a buff force. Restriction of free unit extension prevents slamming of the unit to its fully extended position when buff forces dissipate and prevents the occurrence of undesirable oscillation or rebounding of the cushioning unit. Snubbing systems only provide for dissipating a portion of the internal energy stored within the cushioning unit during compression. Draft cushioning mechanisms, however, contemplate the dissipation of externally applied energy which occurs as a significant draft load is placed upon the coupler structure of a railway car. The draft cushioning mechanism in accordance with the concept of the instant invention therefore must be of significant design capability to achieve a desired degree of cushioning in draft. It is extremely important that the draft cushioning mechanism be capable of dissipating the energy which might occur during a wide range of force applications from severe short duration forces to smoothly applied long duration draft loads.

The present invention provides a cushioning structure in which the hydraulic unit and the resilient draft gear operate cooperatively in both directions, and in which a separate draft or auxiliary cushioning mechanism provides substantial energy dissipating capability in the draft direction from any position up to and including full buff. A particular advantage afforded by the novel construction of the cushioning unit of this invention resides in the prevention of an undesirable condition when the cushioning unit is permitted to go solid under the application of an extremely low velocity impact load such as slack run-in during a downgrade locomotive braking condition. When a sizable number of railway cars are included in a single train, the length of the car may shorten considerably by the sum of the travel of the cushioning units on all the railway cars equipped with such units. If at the end of a downgrade travel the cushioning units of the railway cars have been allowed to go solid and the train is subsequently transitioned from a downgrade travel to an upgrade travel, the slack runouts of the coupled railway cars might occur causing railway car acceleration subjecting the car coupling mechanisms to excessive draft shock forces which could damage the coupling mechanism and subjecting the car lading to severe jarring. Slack run-outs of this nature are effectively controlled by the auxiliary cushioning mechanism of the instant cushioning unit since cushioning occurs not only in buff but also in draft. The auxiliary cushioning mechanisms retard extension of the cushioning unit between the collapsed and static position and allow relatively slow movement of the cushioning unit to its normally extended or static condition. Moreover, because of the cooperative relation of the hydraulic cushioning unit with the resilient draft gear, resilient cushioning is effective at both the full buff and the neutral positions to provide additional cushioning. This produces a smooth force tr nsition between the coupler and the car under frame and effectively prevents the introduction of excessive shock to the cushioning unit.

Accordingly, it is a principal object of this invention to provide a novel hydraulic cushioning unit which provides for a substantial amount of energy dissipation in draft from all positions up to the full buff position of the unit.

It is an object of the present invention to provide an ond-ofcar cushioning arrangement in which a hydraulic cushioning units is employed in both draft and buff with a resilient draft gear being active in both draft and buff under substantially all conditions of operation.

An additional object of this invention is the provision of such an end-of-car cushioning arrangement in which the hydrauilc cushioning unit acts simultaneously in draft with the resilient draft gear.

A further object is the provision of such a cushioning arrangement in which a portion of the hydraulic cushioning unit acts as the rear follower block of the resilient draft gear.

Another object is tr e provision of an end-of-car cushioning structure in which any moment: or eccentric loading exerted against the hydraulic cushioning unit from the coupler is practically eliminated.

The invention accordingly comprises the constructions hereinafter described, the scope of the invention being indicated in the following claims.

In the accompanying drawings in which one of vari ous possible embodiments of the invention is illustrated:

FIGURE 1 is a side elevational view of a plurality of railway cars coupled to each other;

FIGURE 2 is a fragmentary plan view of a railway car underframe having portions thereof broken away showing the hydraulic cushioning unit comprising this invention mounted within a thick sill adjacent the rear end of a draft gear and coupler structure, the cushioning device being illustrated in a neutral position;

FIGURE 3 is a side elevational view of the structure elevated in FIGURE 2 showing details of the underframe structure.

FIGURE 4 is a plan view similar to FIGURE 2, but having the hydraulic cushioning unit comprising the invention illustrated in its collapsed position and acting in series with the draft gear under buff forces;

FIGURE 5 is a section taken generally along lines 55 of FIGURE 4;

FIGURE 6 is a section taken generally along lines 6-6 in FIGURE 4;

FIGURE 7 is a longitudinal section of a hydraulic cushioning unit constructed in accordance with this invention and illustrated in its static or neutral position;

FIGURE 8 is a longitudinal section of the hydraulic cushioning unit of FIGURE 7, but illustrating the cushioning unit in its collapsed position after being subjected to bufl forces;

FIGURE 9 is an enlarged fragmentary sectional view of the invention as shown in FIGURE 6 illustrating the variable draft-buff cushioning mechanism in detail;

FIGURE 10 is a fragmentary sectional view of FIG- URE 9 illustrating the construction of the auxiliary cushioning member in detail;

FIGURE 11 is a sectional view taken along lines 11 11 of FIGURE 10 illustrating the construction of the auxiliary cushioning member in detail.

Referring now to the drawings for a better understanding of this invention, railway cars 10 illustrated in FIG- URE 1 are interconnected by means of couplers 12. The railway cars 10 are provided with underframe structures which include a fixed center sill construction formed through the center of the railway underframe.

The center sill structure designated generally 14 is generally hat shaped as illustrated in FIGURE 6 forming vertical webs 16 connected by an upper horizontal web 18. A pair of horizontal bottom flanges 20 are connected one to each of the side flanges 16. The center sill construction is provided with an open outer end which is flared to receive a coupler member 12 and to allow swinging of the coupler member relative to the center sill construction. Connection between the coupler member 12 and the center sill 14 is achieved by means of a yoke member 22 disposed within the center sill and transmitting forces from the coupler to draft gear and hydraulic cushioning device structure as described in detail hereinbelow. A shank portion 24 of the coupler 12 is connected to the yoke 22 by means of a pivot pin 26. A coupler carrier member 28 is located at the flared portion of the center sill and is biased upwardly to support the shank portion 24 of the coupler 12. While the coupler 12 has been shown as a type F coupler (Association of Amen'can Railroads designation) mounted about a vertical pin, it is to be understood that the present invention may, if desired, be employed with a type B coupler connected to a horizontal key.

Referring now to FIGURES 5 and 6, a draft gear support or carrier is illustrated comprising a support plate 30 secured by nut and bolt combination 32 to outwardly extending flanges 2t) of the fixed center sill structure 14. A wear plate 34 is secured to the support 30. To guide the movement of the yoke 22, a groove or guideway 36 is formed on the underside of the yoke 22 and receives the wear plate 34. The upperside of the yoke 22 has a key 38 fitting between the guides 40 secured to the center sill structure 14.

Mounted within the yoke 22 is a resilient draft gear generally indicated 42 and comprising a plurality of rubber pads 44 separated by metal plates 46. A front follower block 48 in engagement with the draft gear 42 and is adapted to engage front stops 50 secured to the inner surface of the fixed center sill struc ur 14.

As illustrated in FIGURES 2 and 3 and forming an important part of this invention, a hydraulic fluid cushioning unit generally designated 52 is positioned rearwardly of the draft gear 42. Referring now to FIGURES 7 and 8, the hydraulic cushioning unit 52 comprises an outer cylinder 54 and an inner cylinder 56 movably cooperatin in telescoping relationship. Disposed within the inner cylinder 56 is a floating piston 58 dividing the inner cylinder into a pneumatic chamber 62 and an inner hydraulic chamber 63. A fluid chamber 60 formed within the outer cylinder 54 contains a relatively incompressible liquid such as hydraulic fluid. The pneumatic fluid chamber 62 formed within the inner cylinder 56 contains a relatively compressible fluid such as air or dry nitrogen gas. A metering pin 64 secured to the outer cylinder 54 is received by an orifice plate 66 on the inner end of the inner cylinder 56. The inner hydraulic chamber is in fluid communication with the outer hydraulic chamber 60 by means of a metering orifice 67 formed in the orifice plate 66. The free end of the metering pin 64 extends through the metering orifice 67 to control the effective size of the orifice in relation to the relative position of the

cylinders

54 and 56.

The inner cylinder 56 has an end cap 68 thereon which serves the double function of a rear follower block and an externally threaded inner extension 70 engaging internal threads within the inner cylinder 56 as shown in FIGURE 2. The inner cylinder 56 extends through an opening 72 in the yoke 22 and the end cap 68 engages a peripheral shoulder or rim 74 defined inwardly of the yoke 22. Thus, upon forward movement of the yoke 22, which would occur upon the application of a draft force, the shoulder 74 in engagement with the end cap 68 causes extending movement of the inner cylinder 56. The outer cylinder 54 abuts a rear support 76 secured to the fixed sill structure 14. A U-shaped rear follower stop generally designated 78 has a lug 80 which engages a portion of the front face of the outer cylinder 54 as illustrated in FIG- URE 3 to maintain the outer cylinder in its proper position. The rear abutment surfaces 82 on the rear follower stop 78 engage the end cap 68 to limit the rearward travel of the inner cylinder 56 upon exertion of impact forces against the coupler 12, as shown in FIGURE 4.

With reference now to FIGURES 8 through 11 and particularly FIGURE 9 illustrating on important part of this invention, a packing gland adapter 84 is retained at one extremity of the outer cylinder 54 and carries a packing member 86 therein for the establishment of a fluid tight seal between the outer cylinder 54 and the inner cylinder 56. A retainer 85 threadedly engaging the gland adapter 84 retains the packing 86 and an outer bearing 87 in assembly. The outer bearing maintains alignment between the inner and outer cylinders. An inner annular bearing member 88 is retained at one extremity of the inner cylinder 56 for the establishment of bearing engagement between the inner cylinder and the inner wall 89 of the outer cylinder 54.

The packing assembly 86 and the bearing member 88 cooperate to define a variable volume annular auxiliary cushioning chamber 94 between the inner and outer cylinders. An annular pressure responsive fluid flow control mechanism 96 is disposed about the outer circumference of the inner cylinder 56. The flow control mechanism 96 is axially movable relative to the inner cylinder 56 within limits defined by an annular stop member 98 formed on the inner cylinder 56 and a stop surface 100 formed on a spacer member 102. A series of ports 104 are formed in the wall of the inner cylinder 56 and communicate the inner hydraulic chamber 63 with the variable volume auxiliary cushioning chamber 94. As illustrated in FIGURES 9 and 10, a clearance exists between the outer circumference of the flow control mechanism 96 and the inner cylindrical wall 88 of the outer cylinder 54. Hydraulic fluid flowing from the low pressure or inner hydraulic chamber 63 into the auxiliary cushioning chamber 94 therefore passes through the ports 104 and around the flow control mechanism 96 by means of the clearance between the flow control mechanism 96 and the outer cylinder. During the flow of hydraulic fluid into the auxiliary cushioning chamber 94, the flow control mechanism 96 is maintained in the position illustrated in FIGURE 7 by the flow of the hydraulic fluid, the pressure of the fluid being greater on the upstream side thereof. Upon reversal of the flow of hydraulic fluid from the auxiliary cushioning chamber 94 to the low pressure inner hydraulic chamber 63, which occurs during extension of the cushioning unit to its normally extended or neutral position, the flow control mechanism 96 is forced by the flowing fluid to move into engagement with the annular stop shoulder 190 of the spacer member 102 to therefore prevent the flow of fiuid around the flow control mechanism 96 in the return direction.

With reference now particularly to FIGURES l0 and 11, the flow control mechanism 96 includes a generally ring-like body member having at least one and preferably a series of poppet valve constructions which include preventing the flow of hydraulic fluid in one direction and allowing the flow of hydraulic fluid in the opposite direc tion in response to pressure of the hydraulic fluid. Each of the pressure responsive flow control or poppet structurs comprises a stepped valve housing bore 110 which is internally threaded at its outer extremity to receive a valve seat structure 112. The valve seat 112 is provided with an axial bore 114 and a frusto-conical seat surface 116. A poppet 13th is disposed within the bore 110 and is maintained under a predetermined mechanical bias in intimate engagement with the valve seat 112 to establish a fluid tight seal to control the flow of fluid through the poppet.

As illustrated in FIGURE 11, the poppet 113 is a generally rectangular member which when fitted within the cylindrical bore defines a plurality of flow passages around the poppet. A guide member 120 carried by the poppet 118 is provided to maintain alignment of the poppet memher 118 within the bore 11%. A compression spring memher 122 is disposed within the bore 110 encircling the poppet guide member 120 and maintains the poppet 118 in intimate engagement with valve seat 112. An annular groove 123 interconnects the inner periphery of the flow control mechanism with each of the bores 110 and a recess 124 formed at the inner periphery of the flow control mechanism provides a flow passage from the groove 123 to the ports 1% in the inner cylinder 56. The annular reccss 124 obviates the need for precise radial alignment of the flow control mechanism relative to the ports 104. An annular recess 1% is formed at the inner periphery of the llow control mechanism 96 defining an annular shoulder 128 for engagement with the stop 98 on the inner cylinder 56.

Wlere a number of poppet constructions are employed, the opening pressure required for each poppet is varied by providing compression springs of various predetermined compressive values. This allows the poppet constructions to open in series as the pressure differential in the auxiliary cushioning chamber and the internal hydraulic chamber increases. This series poppet operation effectively promotes a smooth force escalation reducing the tendency for the introduction of shock from the coupler to the underframe of the railway car.

With reference now particularly to FIGURES 7 and 8, it is apparent that upon telescoping or compression of the hydraulic cushioning unit 52, which will occur when the cushioning unit is subjected to a bull force, the auxiliary cushioning chamber )4 will increase substantially in volume. As the auxiliary cushioning chamber 4 increases in volume, fluid within the inner hydraulic chamber 63 is forced through the ports 1% and around the fluid flow control mechanism $6 by means of the peripheral clearance between fluid flow control mechanism and the inner wall 8? of the outer cylinder 54. Upon the flow of fluid through the ports ltl r into the auxiliary cushioning chamber 9d, the flow control mechanism 96 will be forced 6 into engagement with the stop 93 in the manner illustrated in FIGURE 7. With the flow control mechanism positioned as illustrated in FIGURE 7, the flow of hydraulic fluid from the inner hydraulic chamber 63 to the auxiliary cushioning chamber 94 is relatively unrestricted. The flow control mechanism under these conditions establishes a fixed flow passage area and the rate of flow of hydraulic fluid into the chamber 94 is determined by pressure within the inner hydraulic chamber 63, and by a partial vacuum or reduced pressure condition which is developed in the chamber 94 when the chamber is suddenly enlarged by the telescoping cylinders.

As the hydraulic cushioning device 52 extends from its compressed condition toward its neutral or static condition, the hydraulic fluid within the auxiliary cushioning chamber 94 must flow past the flow control mechanism 96 and through the ports 104 into the inner hydraulic chamber 63. Under these conditions, the flow control mechanism 96 will be forced by the pressurized fluid within the chamber 94 to move axially into abutment with the annular surface of the member 102 as illustrated in FIGURES 9 and 10, thereby preventing the flow of fluid through the peripheral clearance between the flow control mechanism and the inner wall 89 of the outer cylinder 54. The flow control mechanism is in sliding interfitting relationship with the inner cylinder and the clearance be tween the flow control mechanism and the inner cylinder defines a fixed calibrate-d passage for the flow of hydraulic fluid from the auxiliary cushioning chamber to the ports 104. This calibrated passage structure allows the cushioning device to dissipate energy during low load draft conditions While the variable orifice structure provided by the auxiliary cushioning flow control mechanism remains closed. Under conditions of high draft load, the variable orifice structure will begin to function providing an additional cushioning fluid control supplementing the fluid flow allowed by the calibrated passage. With the llow control mechanism 96 in a position illustrated in FIGURES 9 and 10, the fluid under pressure within the auxiliary cushioning chamber 94 will act through the bore 114 in the valve seat 11;"; upon the check valve member 113. The springs 122 which bias the poppet 118 into engagement with the valve seat 112 are so calibrated that the poppet 118 will not move from the valve seat 112 until such time as a predetermined pressure diiferential is reached between the auxiliary cushioning chamber 94 and the inner hydraulic chamber 63. It is pointed out that the poppet valves do not open at a predetermined fluid pressure within the auxiliary cushioning chamber 94 but rather open responsive to a predetermined differential pressure or pressure drop across the small area fixed orifice defined by engagement between the poppet 126 and the seat 112. As an example of poppet operation, the poppet springs may be calibrated to open in series at a pressure differential around 2200 psi. acting from the auxiliary cushioning chamber 94. With the cushioning unit the extended or neutral position illustrated in FIG- URE 7, the pressure within the gaseous fluid chamber as may be in the order of 266 psi. Assuming the compression ratio of the cushioning unit to be 6 to l, at the fully collapsed position illustrated in FIGURE 8, the gaseous pressure in the chamber 62 will be in the order of 1500 psi, At the full draft position of the cushioning unit the pressure in the chamber 62; will be reduced to roughly 200 p.s.i. by virtue of extension of the cushioning unit beyond its neutral position. The gaseous pressure acts through the piston on the fluid within the inner cylinder and is communicated through the ports 104 to the poppet valves. Under neutral conditions of the cushiong unit, therefore, the poppet valves will be maintained in the closed position by the 260 p.s.i. air pressure in addition to the force produced by the poppet spring and it would require a pressure in the auxiliary cushioning chamber in the order of 2500 psi. to cause the same to open. At the fully collapsed position of the cushioning unit there will be developed around 1500 p.s.i. pressure within the gaseous chamber 62 and through the piston and hydraulic fluid in the inner hydraulic chamber the poppet valves will be maintained closed by the 1500 p.s.i. gaseous fluid pressure plus the mechanical bias of the poppet spring. Since a pressure differential of 2200 p.s.i. is required to open the poppet valves a pressure in the range of 3700 p.s.i. in the auxiliary cushioning chamber would be required to cause opening of the poppets at the full buff position of the cushioning unit. As the pressure between

chambers

94 and 63 increase above the minimum pressure differential required to open the poppets 118, the poppets will open an amount directly responsive to the pressure differential. The poppets 118 therefore allow the flow of fluid thereth-rough only when a predetermined minimum pressure differential is reached within the chamber 94. At pressure above the predetermined minimum, the poppets are calibrated to allow a rate of flow therethrough, which is directly responsive to the fluid pressure differential between the

chambers

63 and 94. As the poppets 118 open, the flow of fluid will be allowed through the passages defined between the poppet 118 and the bore 110 as illustrated in FIGURE 11, through the groove 123, the annular recess 124 and through the ports 104 into the inner hydraulic chamber 63.

It is a particularly important feature of the invention that the hydraulic cushioning unit will provide cushioning in draft regardless of the position thereof, with exception only of the full draft or fully extended position. The fixed draft calibrated passage will provide cushioning for low load draft conditions and should the draft load increase to a sufficiently high range, the poppets will open in series to lend additional energy dissipation capacity. The additional energy dissipation capacity of the poppet structure is, as explained above, directly proportional to the draft load applied to the hydraulic cushioning unit.

The auxiliary cushioning construction including the flow control mechanism with its fixed and variable draft orifice structure and the auxiliary cushioning chamber 94 effectively prevents the hydraulic cushioning units 52 from rebounding subsequent to the occurrence of buff forces and provides for cushioning when the cushioning unit is subjected to draft forces.

Another important feature of this invention is that the cushioning device will act not only in buff, but also in draft in combination with a resilient draft gear. With the cushioning unit in its neutral or static position as illustratcd in FIGURE 9, and with the fluid flow control mechanism in the position illustrated in FIGURES 9 and 10, if a draft force is applied to the inner cylinder 56 through the resilient draft gear 42, the cushioning unit 52 may be further extended beyond its static position. Further extension of the cushioning unit 52 will occur, however, only uopn exhausting a quantity of the hydraulic fluid from within the auxiliary cushioning chamber 94 to the inner hydraulic chamber 63.

Low load cushioning will be achieved by the metering of hydraulic fluid through the calibrated fixed passage structure defined between the flow control mechanism and the outer circumference of the inner cylinder, The poppets 118 in the flow control mechanism 96 will operate in the same manner requiring that the pressure differential between the

chambers

94 and 63 rises to a predetermined minimum before the poppets 118 are unseated and the flow of fluid is allowed through the poppet and through the groove 123, the recess 124 and the ports 104 into the inner hydraulic chamber 63. Even though the length of movement of the inner cylinder from the static position is small, a considerable amount of energy will be dissipated and the cushioning unit will operate quite satisfactory for dissipation of the magnitude of forces anticipated in draft.

As a specific example of a hydraulic cushioning unit embodying the present invention, outer cylinder 54 may have an outside diameter of twelve (12) inches and an inside diameter of nine and on-half (9 /2) inches with chamber 60 having an area of 70.8 inches. Inner cylinder 56 may have an inside diameter of five and one-half (5 /2) inches and an outside diameter of seven (7) inches. Auxiliary cushioning chamber 94 defined between the outer Wall surface of inner cylinder 56 and the inner wall surface of outer cylinder 54 has an area of 32.4 square inches, which is equivalent to a circular area having a diameter of 6.42 inches. Thus, chamber 94 with an area of 32.4 inches comprises about forty-five percent of the entire area of chamber 60. In order to obtain adequate cushioning in draft from cushioning chamber 94 and to maintain an adequate cushioning in buff from chambers and 63, while maintaining fiuid pressures in

chambers

60 and 94 at practical working levels, it has been found that an area of chamber 94 between around twenty-five (25) percent and sixty-five percent of the area of outer chamber 60 is required. It is generally conceded that maximum buff forces are from 2 to 4 times the maximum draft forces. Draft gear 42 normally has a preload of between 10,000 and 20,000 pounds which is exerted against cushioning unit 52 to provide a preloading of cushioning unit 52.

A particular advantage involved in the construction of the instant invention resides in the cooperative operation between the resilient draft gear 42 and the hydraulic cushioning unit 52. For example, as a buff force begins to be exerted upon impact of one railway car with another, the initial shock of the impact is absorbed in part by the resilient draft gear, thereby allowing the shock transmitted to the cushioning unit 52 to be in the form of a smooth force application. The draft gear acting cooperatively with the hydraulic cushioning unit allows relatively slow pressure buildup within the hydraulic unit, thereby preventing the possibility of pressure damage to the hydraulic cushioning unit and insuring long life of the hydraulic cushioning unit by reducing wear of the parts thereof.

In operation, referring particularly to FIGURES 4, 7 and 8, upon exertion of impact or buff forces against the coupler of the railway car, the draft gear 42 will be compressed slightly between the front follower block 48 and the end cap 68 which moves the rim or shoulder surface 74 away from the end cap 68. The front follower block 48 remains in engagement with the yoke 22 and is moved rearwardly by the yoke out of engagement with the stops 50. The hydraulic cushioning unit 52 will remain in its normally extended or static position until the rubber draft gear 24 has become compressed, for example, A" to A2" and the inner cylinder 56 will then be caused to move inwardly in telescoping relation with the outer cylinder 54 to dissipate the energy applied to the hydraulic cushioning unit. Under a maximum buff force, the cushioning unit 52 will collapse or contract until the end cap 63 moves into engagement with the abutment surfaces 82 on the rear follower stop 78, thereby limiting the rear ward travel of the inner cylinder '56 relative to the outer cylinder 54. Engagement between the end cap 68 and the stop surfaces 82 effectively prevents impacting of the orifice plate 66 at the rear end of the outer cylinder 54, thereby eliminating any tendency to damage the orifice plate structure of the inner cylinder. In the maximum collapsed or full buff position of the hydraulic cushioning unit 52 with the end cap 68 in abutment with the stop surfaces 82, the yoke 22 remains spaced from the stop and may move rearwardly an additional amount to further compress the draft gear 42. Thus the rubber draft gear 42 remains active after the hydraulic cushioning unit 52 has gone solid or has reached its innermost position as illustrated in the full buff position in FIGURE 4. After absorption of the buff or impact loads, the gas pressurized within the chamber 62 acting on the piston 58 will force the hydraulic fluid from the inner hydraulic chamber 63 to the outer hydraulic chamber 60 thereby returning the cushioning unit 52 to its normally extended or neutral position.

' With the hydraulic cushioning unit 52 in its fully contracted or collapsed condition as illustrated in FIGURE 8, the auxiliary cushioning chamber 94 will be at its condition of greatest volume and will be filled with hydraulic fluid. Filling of the auxiliary cushioning chamber with hydraulic fluid occurs during collapsing of the cushioning unit 52 in the manner described above in regard to FIG-

URES

10 and 11. As the hydraulic cushioning unit 52 is extended from the FIGURE 8 position to the FIGURE 7 position, by the pressurized compressible fluid within the pneumatic chamber 62, the flow control mechanism 96 will move to the position illustrated in FIGURES 8 and 10, thereby preventing the free flow of hydraulic fluid from the auxiliary cushioning chamber 94 around the mechanism 96 to the inn-er hydraulic chamber 63. As the buif load is released, gas pressure within the chamber 62 acting upon the piston 58 causes the fluid pressure within the chamber 94 to be forced through the orifice 67 into the outer fluid chamber 60 causing the hydraulic cushioning unit to extend toward its neutral position. Fluid within the auxiliary cushioning chamber 94 is forced through the fixed calibrated passage structure in the manner discussed above, and flows through the ports 104 into the inner hylraulic chamber. The restricted calibrated passage structure maintains the rate of extension of the hydraulic cushioning unit at a desired level. The auxiliary cushioning mechanism therefore prevents excessively rapid extension of the cushioning unit, which might otherwise result in slamming the hydraulic unit to its fully extended condition, possibly causing damage to the hydraulic unit itself and causing rebounding or undesirable oscillation of the hydraulic unit prior to stabilizing of the same at the neutral position.

As pointed out hereinabove, the auxiliary cushioning mechanism also provides for dissipation of energy during the application of draft forces when the cushioning device '52 is in its neutral position. Upon the application of a draft force when the cushioning device is in its static position, the yoke 22 will cause the shoulder surface 74 thereof to engage the end cap 68, thereby causing outward movement of the innner cylinder 56. Outward movement of the inner cylinder occurs as the hydraulic fluid within the auxiliary cushioning chamber 94 is displaced into the inner hydraulic chamber 63 in the manner described above. Considerable draft energy is dissipated upon movement of the fluid within the chamber 94 to the inner hydraulic chamber 63. Simultaneously with outward movement of the inner cylinder 56 of the hydraulic cushioning unit 52 from the neutral position, there occurs a compression of the draft gear 42 by the end cap 68 forcing the draft gear 42 and the follower plate 48 into engagement with the front stops 50. The draft extension of the inner cylinder provides an additional cushioning action therefor and acts in cooperation with the resilient draft gear 4'2 in draft even when the cushioning device is originally in its neutral or static position.

Since the end cap is in face to face contact with a resilient pad 44 of the draft gear 42, any eccentric loading applied against the coupler 12 and the yoke 22 will not be transmitted to the inner cylinder 56. Thus minimizes the transmission of any lateral movement to or eccentric loading of the inner cylinder 56 and therefore minimizes malfunctioning of the hydraulic cushioning unit 52. The resilient pad 44, in contact wtih the end cap 68, tends to distribute the forces from the coupler and the yoke 22 to eliminate any lateral moment which might be transmitted to the inner cylinder 56.

From the foregoing, it is evident that I have produced a novel construction for a railway end-of-car cushioning device which allows cooperative operation of a resilient draft gear construction and a hydraulic cushioning unit when the same are subjected to either draft or buff forces. The invention effectively provides for cushioning in draft from any position of the cushioning unit, with exception of the full draft position. The invention also eliminates rebounding of the hydraulic cushioning unit and prevents damage by the hydraulic cushioning unit by providing a combination fixed and variable fluid flow control mechanism which controls the flow of fluid out of an auxiliary cushioning chamber to retard the extension rate of the hydraulic cushioning unit in response to fluid pressure within the auxiliary cushioning chamber. It is further evident that I have provided a hydraulic cushioning unit which, when in the neutral position, allows the dissipation of energy in draft hydraulically in addition to acting in co operation with a resilient draft gear under draft forces. The interrelated cooperation between the resilient draft gear construction and the hydraulic cushioning unit construction of the instant invention effectively prevents slamming of the hydraulic cushioning unit either to its fully collapsed position or to its fully extended position, thereby protecting the cushioning unit from damage. The resilient draft gear effectively allows the smooth transition of energy to flow from the draft gear to the hydraulic cushioning unit, thereby preserving the longevity of the hydraulic cushioning unit and preventing the possibility ofcxcessively high pressures developing within the fluid chambers thereof.

In view of the above, it will be seen that all of the various objects of the invention are achieved and other advantageous results attained.

As various changes may be made in the above construction without departing from the spirit or the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. A railway car having a center sill structure with an open outer end, a coupler mounted for movement within said center sill structure, a resilient draft gear adjacent the inner end of said coupler having a plurality of rubber like pads, a yoke connected to said coupler and extending rearwardly about said resilient draft gear, a hydraulic cushioning unit mounted Within said center sill structure rearwardly of said draft gear, said hydraulic cushioning unit comprising an outer fluid cylinder and an inner fluid cylinder movable between collapsed and maximum extended positions relative to each other, said cushioning unit when not subjected to buff or draft forces being disposed in a neutral position, said inner and outer cylinders defining primary cushioning means and auxiliary cushioning means, said primary cushioning means causing dissipation of energy upon movement of said. cylinders from the extended position to the collapsed position and said auxiliary cushioning means causing dissipation of energy upon movement of the cushioning unit toward its maximum extended position, said auxiliary cushioning means including fluid metering means defining relatively unrestricted passage means for allowing relative unrestricted flow of fluid into said variable volume auxiliary fluid chamber, said fluid metering means defining restricted passage means for fluid flowing out of said auxiliary fluid chamber under fluid pressure below a predetermined pressure to achieve said dissipation of energy, said fluid metering means changing the restricted passage means responsive to fluid pressure in excess of said predetermined pressure to achieve different energy dissipating characteristics of said auxiliary cushioning means, said auxiliary cushioning means dissipating energy in draft in all positions except the maximum extended position of said. cushioning unit.

2. A railway car as set forth in claim 1, said auxiliary cushioning means being operative both in the collapsed and neutral positions of said cushioning unit and acting cooperatively with said resilient draft gear in both of said collapsed and neutral positions to achieve dissipation of energy when the cushioning unit is subjected to draft loads.

3. A railway car as set forth in claim 1 wherein said means on the extended end of said inner cylinder comprises an end cap positioned within said yoke and forming rear follower block for the dr. t gear, said cap being positioned in face to face contact with an adjacent rubber like pad of said resilient draft gear, said end cap permitting a limited rearward movement of the yoke relative to the inner cylinder thereby permitting a limited compression of the draft gear relative to the cushioning device upon the exertion of buff forces against the coupler.

4'. A railway car as set forth in claim 1, said means controlling the flow of hydraulic fluid defining a fixed flow passage when fluid is flowing into said auxiliary cushioning chamber and defining a restricted fixed flow passage for controlling the flow of low pressure fluid from said auxiliary cushioning chamber, variable pressure responsive flow passage structure supplementing said restricted fixedflow passage under predetermined high pressure conditions within said auxiliary cushioning chamber.

5. A railway car as set forth in claim it wherein said means controlling the flow of hydraulic fiuid comprises a ring like body disposed about said inner cylinder in movable relation therewith, said body defining a fixed restricted interior fluid passage with said inner cylinder and defining an exterior fluid passage with said outer cylincler, at least one internal fluid flow passage defined within said body, a biased poppet Within the internal flow passage adapted to prevent the flow of fluid through the flow passage upon collapsing of the cushioning unit and to allow the flow of fluid through the internal flow passage in response to predetermined fluid pressure within the auxiliary cushioning chamber during extension of the cushioning unit.

6. A hydraulic-pneumatic cushioning unit comprising inner and outer telescoped cylinders defining an outer variable volume hydraulic chamber, said cylinders defining a variable volume auxiliary draft cushioning chamber therebetween, the inner cylinder being closed at each end thereof, a floating piston disposed within the inner cylinder and dividing the same into a pneumatic chamber and an inner hydraulic chamber, said pneumatic chamber having a compressible gas therein, one end of the inner cylinder having a metering orifice, the outer cylinder being closed at one end thereof, a metering pin carried by the outer cylinder and adapted to extend through the metering orifice to control the effective size of the same, pressure responsive fluid flow control means in said auxiliary draft cushioning chamber, means establishing fluid communication between the inner hydraulic chamber and the auxiliary cushioning chamber, said fluid flow control means cooperating with said fluid communication means and establishing a fixed fluid passage when fluid is flowing from said inner hydraulic chamber to said auxiliary draft cushioning chamber, said flow control means providing a fixed restricted flow passage for the flow of fluid from the auxiliary draft cushioning chamber to the inner hydraulic chamber when the fluid pressure within the auxiliary draft cushioning chamber is below a predetermined pressure and supplementing said fixed restricted flow passage with pressure responsive variable fluid passage structure when the fluid pressure within said auxiliary draft cushioning chamber is above said predetermined pressure.

7. A hydraulic-pneumatic cushioning unit as set forth in claim 6, first and second spaced stop means in said auxiliary draft cushioning chamber, said flow control means being movable between said stop means, said flow control means when in intimate engagement with said first stop means defining a first fluid flow path from said fluid communication means to said auxiliary cushioning chamber, when in engagement with said second stop means, said flow control means blocking said first fluid flow path and defining a second restricted fixed fluid flow path to control the flow of fluid between the auxiliary draft cushioning chamber and the inner hydraulic chamber.

5'3. A hydraulic-pneumatic cushioning unit as set forth in claim 6, at least one generally cylindrical fluid flow passage formed through said flow control means, each passage having means defining a valve seat about said flow passage, a poppet disposed in said flow passage for sealing engagement with said valve seat, means biasing said poppet into said sealing engagement.

9. A hydraulic-pneumatic cushioning unit as set forth in claim 8, said valve seat comprising a frusto-conical surface formed about a generally coaxial valve seat bore, said poppet comprising a generally rectangular plate disposed within the generally cylindrical fluid flow passage and being normally biased into engagement with said frusto-conical surface to establish said sealing engagement.

10. A hydraulic-pneumatic cushioning unit comprising inner and outer telescoping cylinders defining an outer variable volume fluid chamber, a piston within said inner cylinder dividing the same into a pneumatic chamber and an inner hydraulic chamber, means controlling the flow of hydraulic fluid between the outer and inner hydraulic chambers upon relative telescoping movement of said cylinders, a variable volume auxiliary draft cushioning chamber defined between the inner and outer cylinders and being in fluid communication with the inner fluid chamber, fluid flow control means within said auxiliary draft cushioning chamber and defining an outer fixed flow passage with the outer cylinder to allow the relatively free flow of fluid into said auxiliary draft cushioning chamber upon collapsing of said cushioning device under buff forces, upon movement of said cylinders toward the extended position thereof said fluid flow control means closing said outer fixed flow passa e and defining an inner restricted fixed flow passage with the inner cylinder, when the fluid pressure within the auxiliary draft cushioning chamber rises above a predetermined pressure said fluid flow control means supplementing said restricted fixed flow passage with variable pressure responsive flow passage structure to allow pressure responsive cushioning in response to the application of draft forces to said cushioning unit.

11. A hydraulic cushioning unit adapted to be operatively connected to a railway car coupler, said cushioning unit comprising inner and outer telescoping cylinders defining an inner variable volume hydraulic chamber, an outer variable volume auxiliary draft cushioning chamber defined between the inner and outer cylinders and being in fluid communication with said inner variable volume chamber, fluid flow control means controlling the flow of fluid between said inner chamber and said auxiliary draft cushioning chamber, said fluid flow control means allowing a relatively free flow of fluid into the auxiliary draft cushioning chamber upon retraction of said cushioning unit when buff forces are exerted against the railway car coupler, and means to return the cushioning unit to a neutral position after a retraction of the cushioning unit and the absorption of buff forces, said flow control means during the return of said cushioning unit to the neutral position defining an inner restricted fixed flow passage to permit a generally fixed fluid flow from the auxiliary draft cushioning chamber to said inner chamber, said flow control means including fluid pressure responsive means responsive to a predetermined fluid pressure within the auxiliary draft cushioning chamber to permit an increased fluid flow from the auxiliary draft cushioning chamber to the inner chamber upon the exertion of draft forces against the coupler of a predetermined magnitude when the cushioning unit is returning to neutral position thereby to regulate the cushioning obtained by the flow of fluid from the auxiliary draft cushioning chamber to the inner chamber and to regulate the return movement of the cushioning unit.

12. A hydraulic cushioning unit as set forth in claim 11 wherein said fluid pressure responsive means provides a variable fluid flow with the flow of fluid increasing with an increase in fluid pressure within the auxiliary draft cushioning chamber thereby to regulate the fluid pressure within the auxiliary draft cushioning chamber.

13. A hydraulic cushioning unit as set forth in claim 11 wherein said flow control mean comprises a floating ring mounted about said inner cylinder within said auxiliary draft cushioning chamber, and said fluid pressure responsive means comprises at least one pressure relief valve carried by said ring and actuated at a predetermined fluid pressure in said auxiliary draft cushioning chamber to permit fluid flow from the auxiliary draft cushioning chamber to the inner chamber.

14. A railway car having a center sill structure with an open outer end, a coupler mounted for movement within said center sill structure, a hydraulic cushioning unit mounted within said center sill structure, means operatively connecting said coupler and said hydraulic cushioning unit to permit said hydraulic cushioning unit to cushion both buff and draft forces exerted against said coupler, said cushioning unit comprising inner and outer telescoping cylinders defining an inner variable volume hydraulic chamber, a variable volume auxiliary draft cushioning chamber defined between the inner and outer cylinders and being a fluid communication with said inner variable volume chamber, fluid flow control means controlling the flow of fluid between said inner hydraulic chamber and said auxiliary draft cushioning chamber, said fluid flow control means permitting a flow of fluid into the auxiliary cushioning chamber upon collapsing of said cushioning unit when buff forces are exerted against the railway car coupler, means to return the cushioning unit to a neutral position after a collapsing of the cushioning unit and the absorption of buff forces, said flow control means during the return of said cushioning device to the neutral position defining an inner restricted flow passage to permit a relatively small fluid flow from the auxiliary draft cushioning chamber to said inner hydraulic chamber, and means responsive to a predetermined fluid pressure differential between the inner hydraulic chamber and the auxiliary draft cushioning chamber to permit an increased fluidfiow from the auxiliary cushioning chamber to the inner hydraulic chamber upon the exertion of draft forces against the coupler of a predetermined magnitude when the cushioning unit is returning to neutral position thereby to regulate the cushioning obtained by the flow of fluid from the auxiliary draft cushioning chamber to the inner chamber and to regulate-the return movement of the cushioning unit.

15. A railway car as set forth in claim 14 wherein said hydraulic cushioning unit is operable in draft from said neutral position upon the exertion of draft forces against said coupler.

16. A railway car as set forth in claim 15 wherein said auxiliary draft cushioning chamber defined between the inner cylinder and outer cylinder has an area between around 25% and 65% of the area of the inner fluid chamber defined by the outer cylinder thereby to provide a substantial cushioning upon the exertion of draft forces against the coupler when the cushioning device is returning to neutral position after the absorption of buff forces.

17. A railway car having a center sill structure with an open outer end, a coupler mounted for movement within .said center sill structure, a first cushioning unit of a positive resistance type within the center sill structure adjacent the inner end of said coupler, a second cushioning unit of the hydraulic fluid throttling type mounted within said center sill structure rearwardly of said first cushion ing unit, means to transmit loads simultaneously to said first and second cushioning units upon the exertion of draft forces against said coupler for a simultaneous cushioned travel of said first and second cushioning units in one direction for absorbing said draft forces, means to transmit loads in series to said first and second cushioning units upon the exertion of buff forces against said coupler, said second cushioning unit comprising inner and outer telescoping cylinders defining an inner variable volume hydraulic chamber, a variable volume auxiliary draft cushioning chamber defined between the inner and outer cylinders and being in fluid communication with said inner variable volume chamber, fluid flow control means controlling the flow of fluid between said inner hydraulic chamber and said auxiliary draft cushioning chamber, said fluid flow control means permitting a flow of fluid into the auxiliary draft cushioning chamber upon retraction of said second cushioning unit when buff forces are exerted against the railway car coupler, means to return said second cushioning unit to a neutral position after a retraction of said second cushioning unit to a neutral position after a retraction of said second cushioning unit and the absorption of buff forces, said] flow control means during the return of said second cushioning unit to neutral position providing an inner restricted fixed flow passage to permit a relatively small fluid flow from the auxiliary draft cushioning chamber to said inner hydraulic chamber, and means responsive to a predetermined fluid pressure differential between the inner hydraulic chamber and the auxiliary draft cushioning chamber to permit an increased fluid flow from the auxiliary draft cushioning chamber to the inner hydraulic chamber upon the exertion of draft forces against the coupler of a predetermined magnitude thereby to regulate the cushioning obtained by the flow of fluid from the auxiliary draft cushioning chamber to the inner chamber.

18. A railway car as set forth in claim 17 wherein said auxiliary cushioning draft chamber is defined between the outer wall surface of the inner cylinder and the inner wall surface of the outer cylinder and has an area between around 25% and 65% of the area of the inner fluid chamber defined by the outer cylinder thereby to provide a substantial cushioning upon the exertion of draft forces against the coupler.

19. A double acting hydraulic cushioning unit for a railway buff and draft gear arrangement comprising a relatively small tubular member telescopically movable within a relatively large tubular member, means capping the remote outer ends of said members, additional means secured to the inner ends of said members and providing sliding engagement between the members, said means and members inclosing and forming a liquid receiving auxiliary draft cushioning chamber, said tubular members also defining outer hydraulic and inner hydraulic chambers, a free piston floating within said small tubular member between its ends forming a gas receiving chamber separated from the inner hydraulic chamber by said piston, metering means controlling the interchange of liquid between said outer and inner hydraulic chambers upon relative movement of said tubular members, said cushioning unit having fluid passage means defining fluid communication between said auxiliary draft cushioning chamber and. said hydraulic chambers, said cushioning unit having fluid metering means cooperating with said fluid passage means to define relatively unrestricted passage means for allowing relatively unrestricted flow of fluid into said auxiliary draft cushioning chamber upon compression of said cushioning unit, said fluid metering means cooperating with said fluid passage means to define restricted passage means for controlling the flow of fluid out of said draft cushioning chamber under fluid pressure below a predetermined pressure to achieve said dissipation of energy, said fluid metering means increasing the effective size of said restricted passage means responsive to fluid pressure within said draft cushioning chamber at a pressure above said predetermined pressure to achieve different energy dissipating characteristics of said auxiliary cushioning means.

20. A double acting hydraulic cushioning unit as set forth in claim 19, said fluid metering means including normally closed supplementary passage means, said supplementary passage means opening in response to a predetermined drop of pressure across said metering means.

15 16 21. A double acting hydraulic cushioning unit as set References Cited forth in claim 19, said fluid metering means comprising UNITED STATES A E a plurality of supplementary metering passages disposed 2,994,442 8/1961 Frederick 213 43 in said fluid metering means, each of said supplementary 3,175,699 3/1965 Price et a1 3 metering passages having .a valve normally closing the 5 3,207,324 9/1965 Bl k 213-8 same, said valves opening responsive to a predetermined 3,216,592 11/1965 Peterson et a1. 213-43 pressure drop across said metering means, thereby supple- 2 3/1966 GOldmaIl 213-43 menting the fluid flow through said restricted passage means. DRAYTONE HOFFMAN, Primary Examiner.

'- UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,378,149 April 16, 1968 Richard G. Powell It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 43, cancel "in"; same line 43, "full" should read full buff Column 2, line 9, "A" should appear as the beginning of a new paragraph; line 16, "car" should read train Column 5 lines 2 3 and 24 "structurs" should read structures Column 7, line 75, "on-half" should read one-half Column 9, line 60, "Thus" should read This Column 10, line 2, "by" should read to Signed and sealed this 28th day of October 1969. (SEAL) Attest:

Edward M. Fletcher, Jr. WILLIAM E. SCHUYLE'R, JR.

Attesting Officer Commissioner of Patents