GB144796A - Improvements relating to braking apparatus - Google Patents

Abstract

144,796. McKenzie, Holland, & Westinghouse Power Signal Co., and Castleman, F. M. March 17, 1919. Fluid - pressure; arresting-grips on permanent way.-The motion of running tubs and like vehicles is arrested by friction bars on the track, which are applied to the wheels of the vehicle by pressure fluid supplied through valves which are located on the track and adapted for operation by the vehicle. The friction bars 1 are secured to pistons 6 working in cylinders 7 to which compressed air is admitted by the valve 10 and pipe 8. The valve 10 is actuated by a treadle bar 31 pivoted at 32 and adapted to be depressed by the vehicle wheels 4, whereby the valve member 29 is moved by a rod 33, which carries a counterweight 34 for returning the bar. The valve, which is adapted to return to the release position after a predetermined interval, comprises a double-beat valve 11 which normally connects the chambers 13, 28 on each side of a piston 21 to an exhaust port 16, so that the piston, held by a spring 27, connects the pipe 8 leading from the cylinder 7 to an exhaust port 23 by way of the cavity 22. The chamber 28 is vented through a passage 26 containing a non- return valve. When the plunger 29 is forced inwards by the treadle bar 31, compressed air admitted by the pipe 19 past the valve 11 to the chamber 13 forces back the piston 21 so as to uncover the port 24, thereby admitting the compressed air to the cylinder 7. Air also flows through the restricted passage 25 to the chamber 28 so that after a time the spring 27 is able to return the piston, and the friction bars 1 are withdrawn from the wheels. In a modification, the valve plunger 29 is disposed beneath the bar 31 and the friction-bars 1 are secured to the cylinders of the compressed-air device, the pistons being fixed. In a further modification, the bar 31 actuates electric contacts in the circuit of an electro-magnetic valve which supplies the pressure-fluid. In this case the length of the bar 31 determines the time during which the brake is applied. A hand switch may be provided.