Patent GB-980650-A (GB)
Title: Stop means for mine cars and like rail vehicles
Inventor: BARKER WILFRED
IPC: B61K7/22
Filed: 1962-08-24
Abstract: 980,650. Track brakes. W: H. BARKER & SON ENGINEERS Ltd. July 17, 1963. [Aug. 24, 1962; Nov. 30, 1962], Nos. 32565/62 and 45324/62. Heading F2E. [Also in Division B7] A track brake for stopping a mine car or other rail vehicle comprises a catch member connected to a body having a cylindrical bore and which, when the catch member is engaged with a vehicle moves relative to first and second piston members disposed within the bore so as to force liquid through a restricting orifice arranged in the bore between the pistons, a restraining member preventing movement of the first piston axially of the bore whilst permitting the arrangement of body and pistons to be pivoted in a vertical plane into an inoperative position in which the catch member is not engaged by a vehicle. In one embodiment, Fig. 1, the first and second pistons 18, 20 are secured to a rod 19 so as to be at a fixed spacing, the assembly being slidable in bore 10a of a body 10 which has integrally formed therewith a catch 11 and also has a cap 12 closing one end from which extend lugs 13 having pins 13a slidably engaging longitudinal grooves in a support member 26. One end 27 of the support member forms an abutment to restrain the pistons 18, 20 against forward movement, the other end of the support member being pivoted to a base plate 28 for movement in a vertical plane from the position shown, where catch 11 is positioned for engagement by a vehicle dummy axle 34, to a lowered inoperative position of the brake, this movement being effected by a fluid-pressure cylinder 29 through a resilient link 30 and toggle linkage formed by a crank 31 and link 32. A restricting orifice in the bore 10a is formed by a disc 14 having an aperture 15 through which a portion of the rod 19 which is either tapered or, as shown, has tapering grooves 19a, passes. Further apertures 16 in the disc 14 are normally closed by a spring-loaded annular valve 17. A spring 21 urges the disc 14 against a shoulder 10c in the bore 10a. Fluid fills the space between pistons 18, 20 and expansion is allowed for by the provision of a chamber 23 communicating via passage 24 with the space between the pistons. In operation, engagement of dummy axle 34 with catch 11 causes disc 14 to be moved along the rod 19 by the shoulder 10c, forcing fluid through the orifice formed between the rod and disc which is progressively reduced owing to the taper whereby the vehicle is brought to rest. Spring 21 returns the disc after use, the annular valve 17 opening to afford unrestricted return flow of fluid. In a second embodiment, Fig. 3, the body 10 is slidably mounted on a rod 41 pivoted to a bracket 42 on fixed support 43, the second piston 39 being secured to this rod and the return spring 44 acting between the second piston and a cap at the rear end of body 10. The front end of the body is bifurcated to accommodate between its links a bracket 45 on which abuts a rod 40 which slides in a sealed aperture in the body and carries the first piston 38. The disc 14 is located against movement relative to the body and as before provides a variable orifice by means of the aperture 15 through which extends a rod 46 which is secured to the piston 38 and is either tapered or provided with tapered grooves. The additional apertures 16 in the disc are normally closed by ball valves 37. The operation is as for the preceding embodiment except that in operation fluid flows additionally through passages 46b, 46c in the rods 46, 40 to transfer fluid to and from the space between the first piston 38 and the front wall of the bore in the body 10. Also in the construction a cam mechanism formed by a bell crank 47 and roller 48 is used for raising and lowering the mechanism to move the catch into and out of operative position relative to dummy axle 50 of a vehicle.