Patent GB-840721-A (GB)
Title: Apparatus for retarding or arresting the progress of rail vehicles
IPC: B61K7/02
Filed: 1955-04-25
Abstract: 840,721. Railway vehicle stops. FITZJOHN, A.P., and TURTON PLATTS & CO. Ltd., G. July 24, 1956 [April 25, 1955], No. 11902/55. Class]104 (2).] [Also in Group XXXIV] In a vehicle stopping or retarding apparatus mounted between the rails of a rail track and including a movable stop-member normally supported in the operable position to engage an axle or undercarriage of a vehicle, an hydraulic buffer device associated with the movable stop includes an interconnected hydraulic buffer and compressed air vessel whereby energy is absorbed by displacement of fluid from the buffer against the resistance of opposing fluid pressure in the air cylinder, the stop is disengaged from the vehicle during or after the buffer operation and the build-up of pressure in the air vessels effects recoil of the buffer and the re-setting of the stop. In the arrangement shown in Fig. 1 the appaiatus comprises a frame 10, fixed in a well between the rails of a track, and a housing 11 longitudinally slidable in the frame 10. Fixed to the frame 10 is a bracket 12 carrying an hydraulic buffer 13 in which slides a hollow buffer plunger 15 mounted on a bulkhead 16 carried by the housing 11. The hollow interior of the buffer 15 permits hydraulic fluid to pass under the control of a multi-ported valve 17 to move a floating piston contained in a compressed air vessel 18 which vessel is fixed to the housing 11. An adjustable needle valve 20 determines the amount of bleed between a pipe 19 leading to the air vessel 18 and the plunger 15. A vehicle stop-member 22 pivotally mounted on a bulkhead 21 at the other end of the housing 11 is normally held in a raised position to engage a vehicle axle or other suitable member A by a piston-rod 25 extending from a cylinder 23 pivotally mounted on trunnions 24 on the housing 11. A piston contained in the cylinder 23 is subjected to compressed air pressure on one side to hold the member 22 in the operative position and hydraulic fluid-pressure on the other to move the member to the inoperative position. The apparatus operates in the following manner. When a vehicle axle A contacts the member 22 the housing 11 is moved relative to the frame 10 and the buffer plunger 15 moves into the buffer 13 to displace hydraulic fluid through the multi-ported valve 17 into the cylinder 18 to move the floating piston against the compressed air. On reaching the extreme forward position a lever 29 of the multi-ported valve 17 is operated by a catch 30 attached to the frame 10 so as to shut off, excepting the bleed port, the air vessel 18, whereupon the fluid for the buffer 13 is diverted via a pipe-line 26 and a non-return valve 27 to the cylinder 23 to move the member 22 downwards out of engagement with the axle A. After the member 22 is free of the axle A, the buffer plunger 15 slowly recoils to its initial position as the compressed air in the cylinder moves the floating piston to force the hydraulic fluid past the bleed port in the multi-ported valve 17 into the buffer 13. The hydraulic fluid above the piston in the cylinder 23 is returned to the buffer 13 through a by-pass pipe 28 as the member 22 is moved to the operative position by the compressed air. As the buffer plunger 15 nears the end of its recoil stroke the lever 29 is operated by a stop 31 attached to frame 10, and the multiported valve 17 is operated to open the buffer 13 to the further return of fluid from the vessel 18 and to shut off the flow of hydraulic fluid to the cylinder 23 while opening the buffer 13 to the return of fluid from the cylinder 23 under the action of the compressed air. The needle valve 20 which controls the rate of bleed to the buffer 13 can be adjusted to control the rate of return flow through the bleed port so as to allow a number of vehicles to pass before the member 22 is reset in the operative position. The above apparatus may be modified by omitting the catches 30 and 31 and operating the multiported valve 17 manually. In a modification shown in Figs. 4, 6 and 7, a buffer 42 is provided for the vehicle engaging part 48 and is slidable over a hollow buffer plunger 44 vertically pivotally mounted on trunnions 45 connected to a frame 40 fixed between the rail track. The vehicle engaging part 48 is supported on rollers 51 running over cam paths 52, 53 in a plate 54 secured to the side-plates of the frame 40. The hollow buffer plunger 44 is connected by a non- return valve 55 to the compressed air vessel 56 carried by a plunger head 43. The non-return valve 55 shown in Fig. 7 admits hydraulic fluid from the buffer 44 through an inlet 59 past a spring-loaded valve 58 to the compressed air vessel 56 through an opening 60; an adjustable needle valve 62 restricts return flow of hydraulic fluid from the vessel 56 through a bleed port 61 to the buffer 44. The apparatus operates as follows. When a vehicle axle or similar part A engages to move the stop 48, fluid is displaced from the buffer 44 through the non-return valve 55 against the floating piston 58 and hence the compressed air in the vessel 56 but as the member 48 moves the roller 51 runs on the cam path 52 and the member 48 is moved downwardly out of engagement with the vehicle axle A. On releasing the axle A the member 48 is returned to its initial position, the roller 51 engaging the cam path 53. The speed of recoil is determined by the adjustment of the needle valve 62. In a modification, shown in Fig. 8, of the arrangement shown in Fig. 4, the vehicle axle engaging part 72 is supported by rollers 73 running in horizontal tracks 74 in vertical slidable guides 75. In this arrangement the vehicles can be retarded or arrested by raising. or lowering the slide 75 by rods 78 operated by a piston 80 in an hydraulic cylinder 77 to move the part 72 into or out of the operating position. The piston is operated under the control of manual actuated means. In a modification of Fig. 8, Fig. 10 (not shown), the verticallymovable slides 75 are actuated by coupled bellcranks. In a further modification, shown in Fig. 12, the buffer casing 100 is slidable on a hollow buffer plunger 101, the bore of which communicates with the air vessel 104, provided with a floating piston 107, through a passage 106 in a back-plate 105 supported by trunnions passing through slide-plates 102. The forward end 108 of the side-plates 102 pivotally support a vehicle stop-member 110 and the lower edges of the side-plates 102 are joined by a cross-plate 112 which rests on a roller 115 running on a base 116 of the frame accommodating the buffer and carried at the end of an hydraulic ram or other reciprocating member. The lever 110 is normally held against a stop 118. The apparatus operates as follows. When the member 110 is pivoted by the vehicle axle A the buffer casing 100 is pushed by a member 111 to displace hydraulic fluid, on a reducing scale due to the metering-pin 117, into the air vessel 104 to move the floating piston 107 against the compressed air. When the vehicle axle A is released from the lever 110 the hydraulic ram or other member carrying the roller 115 is automatically or manually withdrawn to the right of Fig. 12 so that the apparatus pivots down to disengage the member 110 and the axle A. After the axle release the roller 115 is again moved to set the apparatus in the operative position.