US3489295A

US3489295A - Draft gear for railroad car

Info

Publication number: US3489295A
Application number: US652548A
Authority: US
Inventors: Erwin H Hartel
Original assignee: Cleveland Pneumatic Tool Co
Current assignee: Cleveland Pneumatic Tool Co
Priority date: 1967-07-11
Filing date: 1967-07-11
Publication date: 1970-01-13
Anticipated expiration: 1987-01-13

Description

5. H. HARTEL I DRAFT GEAR FOR RAILROAD CAR Jan. 13, 1970 Y s Sheets-Sheet 1 Filed July n, 1967.

mm mm Yv mm ,0?

INVENTOR ERWIN H. HARTEL BY M ATTORNEY Jan. 13, 1970 H. HARTEL 1 3,489

I DRAFT GEAR FOR RAILROAD CAR Filed July 11, 1967 1 s Sheets-Sheet 2 III- 2% Ufll I INVENTOR.

ERWIN H. HARTEL ATTORNEY Jan. 13, 1970 v E. H. HARTEL 3,489,295.

DEA FT GEAR FOR RAILROAD CAR Filed July 11, 1967 6 Sheets-Sheet 4 26 v INVENTORY EIRWIN H. HARTEL FIG. 6- I BY WH ATTORNEY Jan. 13, 1970 E H.'HARTEL DRAFT GEAR FOR RAILROAD CAR 6 Sheets-Sheet 5 Filed July 11. 1967 INVENTOR.

ERWIN H. HARTEL BY ATTOR Jan. 13, 1970 E. H. HARTEL 3,489,295

I DRAFT GEAR FOR RAILROAD CAR Filed July l1, 1967. 6 Sheets-Sheet 6 244 220 I ii I5.

228 "II 255 254 250 23s 248" 252 253 23s 2l6 234 230 F/GI8 I 224 MMIWWMIQ INVENTOR.

ERWIN H. HARTEL WWW ATTORNEY United States Patent US. Cl. 213-8 4 Claims ABSTRACT OF THE DISCLOSURE,

A railroad car draft gear of hydraulic cylinder and piston form in which the rate of response is varied automatically upon changes in the loading of the car to provide greater or lesser damping in relation to the weight of the car. Two weight sensors are operative at each end of the car to effect the adjustment of the damping characteristic with an equalizing or balancing interconnection to eliminate sway as a factor in the adjustment. The gear includes a metering pin assembly which provides a predetermined load-stroke curve and such assembly is adjusted to vary the magnitude of this curve. The weight sensors are of piston and plunger type and can be incorporated in vertical hydraulic shock absorbers replacing the conventional wheel truck springs.

The present invention pertains, generally, to an improved draft gear for the protection of railroad cars from butfing shocks and coupler impacts.

More particularly, this invention relates to a kinetic energy absorbing device or hydraulic draft gear that is so constructed and arranged as to cooperate with a pair of weight sensors to adjust and regulate the damping characteristics of the draft gear or shock absorber with respect to the value of a load applied to a railroad car.

Accordingly, it is a primary object of the present invention to provide a hydraulic draft gear that is so constructed and arranged as to enable limited adjustment of the damping characteristics thereof in response to the load applied to a railroad car.

Another primary object of this invention, in addition to the foregoing objects, is to provide Weight sensors that are so constructed and arranged as to be cooperative with a draft gear comprising a metering pin assembly that is connected to a linkage arrangement designed to compensate for any unbalanced load or weight condition on the framework of a railroad car.

Yet another primary object of the present invention, in addition to the foregoing objects is to provide a hydraulic shock absorber that is so constructed and arranged as to maintain the same amount of travel of the shock absorber plunger substantially irrespective of the weight of the car.

A further primary object of this invention, in addition to each and every one of the foregoing objects, is to provide a combined weight sensing unit and hydraulic shock absorber that is so constructed and arranged as to cooperate with the hydraulic draft gear of the present invention.

Still further, it is a primary object of the present invention, in addition to each and every one of the foregoing objects, to provide a hydraulic draft gear and a pair of weight sensors that are cooperative with a center sill type of railroad car.

Other objects and important features of the invention will be apparent from a study of the specification following taken with the drawings, which together show, illustrate, describe and disclose preferred embodiments or modifications of the invention and what is now considered to be the best mode of practicing the principles thereof.

In the drawing:

FIGURE 1 is a side elevational view, partly in section, showing the improved draft gear or load shock absorber and the load sensing device of the present invention as embodied on a conventional railroad car;

FIGURE 2 is a plan view of the shock absorber and sensing device of FIGURE 1;

FIGURE 3 is a front elevational view taken along the line 33 of FIGURE 1;

FIGURE 4 is an enlarged fragmentary view in section of the load shock absorber illustrated in FIGURE 1;

FIGURE 5 is a sectional view taken along the line 55 of FIGURE 4 looking in the direction of the arrows;

FIGURE 5A is a sectional view similar to that of FIG- URE 5 but illustrating the metering pin of the present invention in a vertical position or one of minimum flow;

FIGURE 6 is an enlarged side elevational view, partly in section, of the load sensing device shown in FIGURE FIGURE 7 is an enlarged detailed end view taken along the line 77 of FIGURE 4 with the cover of the linkage arrangement removed, and showing, in part, the details of the connecting linkage between the load sensing device and shock absorber of the present invention;

FIGURE 7A is a view similar to FIGURE 7 with the connecting linkage in a second condition of adjustment; and

FIGURE 8 is a side elevational view of a modified load sensing device embodying an integral hydraulic shock absorber.

With reference now to the drawings, and particularly FIGURES 1-7, there is illustrated therein a draft gear or hydraulic shock absorbing assembly 20 that is particularly adapted to cooperate with

weight sensing arrangements

22 and 24, enabling the damping characteristics of the shock absorber 20 to be controlled. Accordingly, the shock absorber will be responsive to variations in the load applied to a railroad car 25, the

wheel trucks

26 and 28 of which are clearly illustrated in FIGURES 1, 2 and 3.

Conventionally, most railroad cars are equipped with four wheel-trucks and two shock absorbers, one for each end thereof. In practicing the principles of this invention, four hydraulic weight sensors are employed, two for the front set of two trucks and two for the rear trucks.

Trucks

26 and 28 as well as the other two trucks (not shown) are mounted by conventional means to a center sill 30, which is centrally provided about the longitudinal axis of generally all railroad cars.

The hydraulic shock absorber 20 of the present invention is suitably disposed within a translatable striker box 32 which is preferably keyed to a sill 30 through the medium of

keys

34 and 36. Protruding from the outer exposed end of the striker box 32 is a standard coupling 38 particularly adapted to be positioned and in turn keyed to the striker box through the medium of a key 40. These two keying arrangements are preferably of the pin and slot type although other suitable keying arrangements may also be employed in the practice of the invention provided they function in a similar manner. The

keys

34, 36 and 40 are provided to maintain coupling between adjacent cars through coupler 38, inasmuch as the hydraulic shock absorber 20 operates only under compressive loads.

The

hydraulic weight sensors

22 and 24, which will be described hereinafter in greater detail, are particularly adapted to be mounted upon the frame of car 25 and, respectively, to

car trucks

26 and 28 to which the wheels 42 of the car are fixedly mounted for rotation. It should be noted that the dimensions of the slots in the striker box 32 and sill 30 for each of the above described keys are chosen to provide maximum translation of these elements. A suitably cushioned assembly or resilient rubber packing 44 is provided between the outer exposed end of the coupler 38 and the striker box 32 as an additional or further snubbing unit.

As best shown in FIGURES 1 and 4, the shock absorber 20 has one end 46 in abutting engagement with the striker box 32 and the other end 48 thereof in abutting engagement with the framework 50 forming a part of the sill 30. The shock absorber 20 itself suitably comprises a piston or plunger 52 provided with a piston-head 54 of generally cylindrical configuration at the inner end thereof. The piston-head 54 is disposed within a first fluid chamber 56 formed by the housing 58, the configuration of the chamber 56 corresponding generally with that of the piston-head54 to preclude leakage. Because the shock absorber 20 operates only under a compression load, it is maintained in the expanded position by a compression spring 60 which is disposed between and in engagement with one end of the housing 58 and a plate 62 which in turn is fixedly secured to the plunger 52 adjacent the end 46 of the shock absorber 20.

As shown in FIGURES 4 and 5, the shock absorber 20 comprises, still further, a metering assembly comprising a grooved longitudinally dimensionally extensive annularly or cylindrically configured tube or hollow shell 64, and a metering pin 66, both of which are positioned within the housing 58. The metering pin 66 comprises two oppositely disposed tapered metering channels, flutes or grooves 68, and is rotatably mounted within the shell 64 from an end thereof supported by the housing 58, The shell 64 is suitably secured, such as by welding, to an end plate or end flange 70 which is, in turn, suitably fastened and aligned with pin 72 to the other end 48 of the shock absorber 20.

The piston-head 54 is provided with an annular opening 74, enabling it to be slidably engaged with the shell 64 of the metering assembly. To prevent loss of fluid from the shock absorber housing 58, a sealing structure comprising an annular seal 76 is suitably disposed between the piston-head 54 and plunger or piston 52 which are suitably secured together by

conventional fasteners

78 and 80. This seal 76 is also operatively associated with and acts to guide and align the axial movement of the piston-head 54 and piston 52 along the hollow shell 64. A suitable piston seal 82 is also provided between the piston-head 54 and the housing 58, and a suitable spring loaded one-way check valve 83 provided in the pistonhead 54, which operates as a snubber during the compression stroke of the piston 52, as will be more clearly described hereinafter in the operation of the present invention.

It will be understood that the piston 52 is provided with a longitudinally extending annular clearance opening 84, of a greater diameter than the shell 64. Thus, the piston 52 is capable of moving longitudinally relative to the shell 64 and the metering pin 66 of the shock absorber 20, the latter being longitudinally immovably mounted upon the housing 58 at the end 48.

On the downstream side of the piston 52 is a chamber 86 having a annular shaped air-filled bellows 88 which is responsive to fluid being delivered into the chamber from the fluid chamber 56. The hydraulic fluid which is disposed within the chamber 56 is metered between the grooved shell 64 and metering pin 66 and through ports 90 into chamber 86 on the downstream side of the piston 52. The bellows 88 will collapse when the pressure in chamber 86 increases. The volume of the bellows will thus decrease. This change in voume of the bellows 86 provides additional volume to chamber 86 which is at least equivalent to the volume displaced by the piston-head 54 entering the chamber 56 during the compression stroke, the latter being generally of the order of about 9 inches. It should be apparent that a balanced condition exists between the chambers so that the totally enclosed system can be maintained without loss of fluid.

The check valve 83 permits flow from first chamber 56 to second chamber 86 provided a predetermined overloading force is applied to the piston 52 of the load shock absorber 20. Thus, high impact coupling or buff forces would cause the check valve 22 to function and facilitate the rapid flow of fluid from chamber 56 to 86 so as to smooth out sudden coupler forces and, accordingly, protect the railway car and its contents from damaging jars and oscillatory movements.

The bellows 88 may be fabricated in any suitable manner and of any suitable material, such as an ealstomer or synthetic rubber, or it may be formed from other conventional substances that will resist the hydraulic fluid employed in the shock absorber 20' and retain the pleating employed. In addition, the material should not only be resistant to the fluid employed, but also exhibit good tear resistance in any direction, low temperature flexibility and resistance to attack by industrial atmosphere. The bellows 88 is shown in FIGURE 4 to be of a two piece construction; however, it should be obvious that the belows can also be a one-piece unit.

As best shown in that figure, an annular plug assembly comprising a plug 91 having an integral hollow longitudinally extending central portion 92 is provided between the open end of housing 58 and piston 52. The plug 91 is seated on a shoulder (not shown) provided on the internal bore forming chamber 86 and is maintained in place in axial alignment by suitable retaining means, such as ring 94. Fixedly secured in any suitable manner to the plug 91 and between same and the piston 52 is an inner ring element 96. Between the inner ring element 96 and the bottom inner end 98 of the hollow longitudinally extending central portion 92 of plug 91 is a spring loaded seal assembly 100 which precludes leakage of fluid from chamber 86 past the piston 52. Similarly, a somewhat different but suitable O-ring type of seal 102 is provided about the outer periphery of plug 91 to seal the fluid in chamber 86 and preclude leakage at this region. One end of the bellows 88 is free-floating and the opposite end is suitably attached to an outer annular land portion 104 of plug 91 so that the bellows can be readily replaced if necessary during periodic servicing of the equipment.

As clearly shown in FIGURES 3, 4 and 7, one end 106 of the metering pin 66 extends outwardly from the shock absorber housing 58 and is in abutting engagement with an adjusting pin and grooved linkage arrangement 108. The arrangement 108 is adapted to be operatively associated with the

weight sensors

22 and 24. A first link 110 having an arcuate groove 112 is fixedly secured in any suitable manner, such as by split clamping means 114, to the extension of metering pin 66', and a second connecting link 116 having a free floating pin 118 in camming engagement with the groove 112 of link 110 is fixedly attached at each end to

weight sensors

22 and 24, through the medium of

connections

120 and 122, respectively.

Cables

124 and 126, which are attached to

connectors

120 and 122, are respectively disposed within

flexible conduits

128 and 130 which, in turn, are operatively associated with and communicate respectively with the

weight sensors

22 and 24.

As best shown in FIGURE 6, each weight sensor comprises a ram or piston 132 and an associated cylinder arrangement 134 biased by compression spring 136. The cylinder 134 is suitably secured to the framework 50 which forms part of the sill 30 through the medium of a clamp 138. A suitable clamp suitably fastens the piston 132 to the corresponding wheel truck. The framework 50 of the railroad car is conventionally suspended through coiled compression springs 142 to the wheel trucks at both ends of the car thereby providing the suspension between the wheel and truck arrangement and the main framework of the car.

The opposite end of cable 124 is suitably secured to inwardly protruding stems or flanges 144 radially extending outwardly from a pair of hollow upper and lower sliding tubular members or Sleeves 146 which are in longitudinal sliding relationship with respect to the piston 132. If desired, the sliding tubular members 146 can be of a one piece construction with a single integral inwardly extending stem or flange. During the downward movement of the cylinder 134 the conduit 128 will be correspondingly moved in a downward direction. Due to the viscosity of the fluid filling the gap between the conduit and cable, the cable 124 will also be moved downwardly and will thereby cause upper sleeve 146 to compress the spring 136 and unseat it from the inwardly extending radial shoulder 148, of lower sleeve 146. As the railroad car framework 50 has settled to a new position responsive to loading thereon, the spring 136 will expand moving the sleeves 146 and cable 124 in an upward direction. This movement, being gradual, is effectively achieved inasmuch as the viscosity characteristics of the fluid between the cable 124 and conduit 128 have been predetermined. A hydraulic fluid, particularly a silicone fluid having a viscosity of about 50 to about 100 centistokes would be suitable in the practice of the invention.

Consequently, an upward movement of the cable 124 will also cause the necessary adjustment in the linkage arrangement 108. In turn, the metering pin 66 will rotate to a location properly restricting the operational characteristics of the shock absorber 20 to the additional weight. It should also be apparent that the piston 132 and associated cylinder arrangement 134 and spring 136 are provided to reduce the effect of the shock absorbing function of spring 142, since any upward movement of the piston 132 will compress the spring 136 separating it from the shoulder 150 on the upper sleeve 146. The spring 136 is maintained between the inner walls of the piston 132 and the outer walls of the sleeves 146 by means of suitable annular-shaped pressure pads 151.

The use of a fluid having a desired or predetermined viscosity between the

cables

124 and 126 and the

conduits

128 and 130 substantially eliminates and minimizes any perturbations in the shock absorber springs 144. Additionally, the properties of any such fluid employed should be such that large forces are needed to effect a rapid movement between relatively movable members having the fluid disposed therebetween. It should be noted that a small amount of force applied to one end of the sleeves 146 will effect movement between the cable 124 and conduit 128, if the force is applied gradually, as for instance, by placing additional Weight on the framework of the railroad car, Thus, any oscillations or rapid jounce-type movements of the wheels and trucks against the shock absorber springs 142 will have little effect on the movement of the sleeve 146 and cable 124.

Referring again to FIGURE 4, any rotation of the metering pin 66 will open or close the porting between the pin 66 and the slots 152 in the grooved shell 64. All reduction in openings of the slots 152 are designed such that a restriction is imposed which will in effect reduce the flow of fluid from chamber 56 to chamber 86. Accordingly, the net effect of rotating the metering pin 66 is to substantially decrease the velocity of the piston-head 54 during a buff or power stroke, thereby resulting in a hard but gradual shock absorbing effect. Similarly, when the weight of the railroad car is reduced, the cylinder 134 in the weight sensor 22 will move upwardly, in turn causing the cable 124 to move upwardly and thereby rotate the linkage arrangement 108 connected to the metering pin 66. The volume of fluid passing from chamber 56 to chamber 86 will therefore increase. This location of the metering pin results in a soft shock absorbing effect while still maintaining the 9 inch stroke of the plunger and cylinder arrangement. The width of the slots 152 and the springs between adjacent slots contribute in providing the above effects with maximum efficiency.

It should be noted that if one side of the railroad car is heavier than the other, one weight sensor will tend to adjust the metering pin by a pivotal movement of the linkage arrangement 108 about the axis of the metering pin. The linkage arrangement 108 is responsive to any unbalanced weight condition on the framework of the railroad car, enabling such conditions to be compensated for by a rotation of the metering pin in response to any cable movement generated at the weight sensor. Thus, the present invention solves the problem of weight adjustment and maintains the same amount of travel of the shock absorber piston or plunger 52 regardless of the weight of the railroad car by employing weight sensors and a cooperative metering pin which will adjust the unit to the desired shock absorbing characteristics.

In the operation of the load shock absorber and weight sensors of the present invention, any initial load condition imposed upon the railroad car is initially sensed by the four weight sensors. These weight sensors register any signal imposed upon them. For example, a downward movement of cylinder 134 and conduit 128 will, in turn, due to the motion transmitted to the cable 124 via the viscous substance disposed therebetween, cause a like movement to the linkage arrangement 108. It should be noted that a large movement of the conduit will cause corresponding motion to the cable 124 which will, in turn, generate a large angular rotation of the metering pin 66. As best shown in FIGURE 7, the

cables

124, 126 are illustrated in their lowermost position. In this position of the cables the rate of flow of fluid in the shock absorber will be at a maximum, since the load is heavy, and maximum metering of fluid is desired. This position of the .metering pin is best illustrated in FIGURE 5. In that figure, the pin is illustrated as being disposed in a horizontal position, so that it will be understood that the flow passage defined by the position of the slots 152 of the sleeve 64 and the grooves 68 of the metering pin 66 rela tive to one another is at a maximum.

The rate of absorbing shock is primarily a function of the metering arrangement between the

chambers

56 and 86 illustrated in FIGURE 4. For light loads smaller flow of fluid is required whereas the heavier the loads the greater the flow. In this regard, the initial setting of the metering pin 66 is primarily a function of the weight of the railway cars as measured and sensed by the weight sensors. This setting basically does not change except for up and down bouncing or jouncing movements of the car over the tracks. This setting can be viewed as a course adjustment of the load shock absorber, whereas the adjustment of the position of the piston-head within the cylinder can be considered as a fine or vernier type of adjustment that is due to a buff or impact shock against the coupler. Note that the size or width of the slots 152 is greatest near the free end of the sleeve 64, since maximum flow is desired during the initial portion of the stroke of the piston, inasmuch as the impact against the coupler and piston is greatest during the period immediately following impact. In this regard and for the same reason, the space between adjacent slots near the free end of the sleeve 64 are of lesser extent than at the fixed end.

As a is shock absorbed, the piston travels into the cylinder. The absorbing characteristics desired of the shock absorber become less demanding, since the shock gradually diminishes in scope and force. Consequently, the size of the slot openings become narrower in width and the spacings or gaps between adjacent slots become greater near the fixed end of the sleeve 64. Thus, it should be apparent that the flow of hydraulic fluid between the chambers of the shock absorber is constantly varied, adjusted and regulated so as to provide the ideal flow conditions therebetween, regardless of the load condition on the railroad car or of the shocks transmitted axially along the center sill thereof. Any coupling impacts are therefore smoothly absorbed and free from violent rebounds and oscillations. Thus, the car loading is protected from damage.

Referring to FIGURE 7a, the

cables

124, 126 are illustrated therein in their uppermost position. In this position of the cables, the rate of flow of fluid in the shock absorber will desirably be at a minimum, since the load will be lightest. This position of the metering pin is best illustrated in FIGURE A. In that figure, the pin is illustrated as being disposed in a vertical position so that it will be understood that the flow passage defined by the position of the slots 152 of the sleeve 64 and the grooves 68 of the metering pin 66 relativeto one another is at a minimum. It should be realized that, since the

cables

124, 126 are in their uppermost position, the movement of connecting link 116, which is operatively associated with and causes the free-floating pin 118 to act upon the cam or arcuate groove 112 of link 110, causes the link 110 to roate itself and the metering pin 66. Of course, any further small upward and downward movements of the cables will register as a slight angular movement or rotation of the metering in.

As noted, the slots 152 vary in width and spacing while having the same length, and the relative rotation of the metering pin thus alters the metering effect equally but with differing magnitude. The variation in the width of the slots, and holes or other specific opening forms could as Well be utilized, is computed to yield an efficient loadstroke curve for this metering assembly, with the adjustment affording. such change in the magnitude of the load without distortion of curve.

During the compression stroke of the piston 52, shown in FIGURE 4, the check valve 83 will initially open due to the higher pressure of chamber 56. Once chamber 86 develops a pressure comparable to the pressure in chamber 56, the spring valve will close and thus a more nearly equal pressure will settle across the chambers. This valve 83 facilitates the rapid absorption of shock in cases where, although the flow conditions through the metering arrangement are maximized, it is still not fast enough to accommodate the shock.

FIGURE 8 illustrates a modified load sensing device constructed in accordance with the principles of the present invention. As shown therein, the modified load sensor comprises weight sensing structure and integral hydraulic shock dampening structure, the latter serving primarily as a sway damper supplemental to the conventional coil springs of the railroad wheel trucks, such as the spring 142 shown and described in connection with FIGURE 3. It should be noted initially that the weight sensing feature of this modified device is responsive only to the settling effect of the railroad car frame with respect to the wheel trucks due to variations in the load carried on the frame. The structure and function of such a modified device, therefore does not affect the movement of the linkage arrangement in such a way as to vary the effect of the shock absorber contained in the striker boX. The damper shown in FIGURE 8 compensates for any vertical movement, whereas the shock absorber heretofore described and disclosed is located at the end of each of the car couplings or couplers and is adapted to compensate for and absorb shocks and forces applied thereto.

The load sensing and shock dampening assembly of FIGURE 8 comprises a cylinder of main outside housing 216, and a plunger or piston 218 that is movable relative thereto through the medium of a biasing compression spring 217. A first extending bracket or clamp 220 secured to the housing 216 at one end thereof is disposed so as to jut generally radially out therefrom, and isfixedly secured to the railroad car frame 222. A second extending bracket or clamp 224 fixedly atached to the piston 218 at its lower end is fixedly secured to wheel truck 226.

' The opposite end of cable 124 is suitably secured in a manner similar to that shown in FIGURE 6 to protruding stems or flanges 228 extending radially inwardly from a pair of hollow upper and lower tubular members or sleeves 230. The sleeves are in longitudinal sliding relationship with respect to the piston 218. This portion of the modified load sensing device functions in a manner similar to the weight sensors of FIGURE 6, and thus no need is seen to again repeat the operation thereof.

The integral shock absorbing means of the embodiment shown in FIGURE 8 is comprised of a first chamber 232 and a second chamber 234, each of which contains a suitable hydraulic oil, and is formed by the cylinder or main outside housing 216 and a piston head 236. The piston head 236 is suitably secured, as by welding, to a hollow sleeve or inner tubular member 238 which, in turn, is fixedly secured by a weld 240 to the piston 218. The ends of the hollow sleeve or inner tubular member 238 are respectively sealed from the main outside housing 216 and a lower cover member 241 by resilient tubular sealing means 242 and 244. These

seals

242 and 244 are secured to opposite ends of the inner tubular member 238, to the housing 216, and cover member 241 by suitable tongue-and-groove structure 246.

The piston head 236 is provided with a pair of

ports

248 and 250, both of which are respectively controlled by suitable spring-

type flapper valves

252 and 254 having

openings

253 and 255, respectively. When the piston 218- moves upwardly, the inner tubular member 238 will also move upwardly thereby causing movement of the piston head 236. Fluid in the first chamber 232 will enter port 248 and react against the spring type flapper valve 252. Once the pressure of the fluid in the first chamber 232 exceeds the spring rate, the flapper valve 252 will open, enabling fluid to enter the second chamber 234. In a similar fashion when the piston moves in a downward direction which may occur during the rebound portion of the stroke, fluid in second chamber 234 will enter port 250 and exert pressure against the spring type flapper valve 254. The latter flapper valve is rated the same as the flapper valve 252, and, thus, at such time when the pressure in second chamber 234 is greater than the spring rate fluid will enter the first chamber 232. It should be noted that this interaction of the fluid above the predetermined rate of the flapper springs causes a metering of the flow of fluid between the chambers 232 and 235, enabling this metering function to mitigate the shocks by absorbing them. The chambers thus, in effect, define shocks absorbers that respond to perturbations of a railroad car travelling over track.

It will be appreciated that the improvements disclosed herein in connection with one type of draft gear, viz. a single acting shock absorber for buff operation only, can also be beneficially applied to double acting shock absorbers which operate also in draft. Similarly, there is no practical limitation to fixed sill car constructions and, to the contrary, the improved load sensing and shock absorbing assembly can as readily be used in the sliding center sill type of railroad car.

I, therefore, particularly point out and distinctly claim as my invention:

1. In combination with a railway car having a bed, wheel structure resiliently supporting the same, car coupling means including hydraulic shock absorbing means, and an adjustment device for varying the damping characteristics of the shock absorbing means in response to loading of the car; actuator means for said adjustment device, said actuator means comprising a cylinder and a plunger slidable therein, one of said cylinder and plunger being operatively connected to the car bed and the other to fixed wheel structure to provide relative movement of the cylinder and plunger with change in the weight load applied to the bed, a conduit extending from one of the cylinder and plunger, a cable extending from the other of said cylinder and plunger within said conduit, viscous fluid filling the conduit for coupling of the same and the cable, whereby relative movement of the cylinder and plunger produces through such coupling relative movement of the conduit and cable, and means for applying the relative movement of the conduit and cable to said actuator means for operation of the adjustment device to vary the shock absorbing means.

2. The combination as set forth in claim 1, wherein the cable is connected to the plunger through spring means.

3. The combination set forth in claim 2, wherein the cylinder includes a chamber containing hydraulic fluid and the plunger has a ported head movable in said chamber with shock absorbing effect.

4. In combination with a railway car having a frame, wheel trucks for supporting said frame including coil springs, car coupling means including hydraulic shock absorbing means, adjusting means for regulating the damping characteristic of the shock absorbing means in response to loading of the car; an integral weight sensor and vertical hydraulic shock absorber at each wheel truck, comprising a cylinder and piston slidable therein connected between the car frame and wheel truck in bridging relation to the coil springs of the same, the piston having a head within and normally intermediate the ends of the cylinder to form therewith upper and lower chambers, hydraulic fluid filling said chambers, valving means in said head for permitting metered flow of the fluid between the chambers upon relative movement of the head, with damping thereof, actuating means for said adjusting means, and mechanical connecting means including fluid-coupled members operatively connected respectively to the cylinder and piston for producing an actuation signal at said actuating means responsive to the damped relative movement of the cylinder and piston under loads applied to the car.

References Cited UNITED STATES PATENTS 3,033,384 5/1962 Zanow et a1. 213-43 3,164,262 1/1965 Price et al. 2l38 3,259,252 7/1966 Peterson 213- 43 DRAYTON E. HOFFMAN, Primary Examiner US. Cl. X.R. 213-43