GB438363A - Improvements in or relating to fluid operated brake mechanism - Google Patents

Abstract

438,363. Fluid - pressure brakes. STITT, R. R., 1929, Glendale Avenue, Detroit, Michigan, U.S.A. May 12, 1934, No. 14403. [Class 103 (i)] Valve mechanism for fluid-pressure brakes comprises parts connected respectively to the brake piston and to the pedal or equivalent to give a " follow-up " action and a piston or equivalent subject to the opposing pressures of the cylinder and a spring and interposed in the parts to accelerate the follow-up action and assist in maintaining the cylinder pressure for a given position of the pedal. The valve casing 4 is connected by rod 12 to the brake operating shaft and a rod 14 to which is secured the valve-operating finger 19 is connected to the pedal. The finger 19 is adjustably secured to the rod 14 by nuts 18 and a sleeve 17 which slides in the casing. The casing 4 is connected by a union 28 to the supply reservoir and by union 27 to the brake cylinder. The chamber 41 is connected by a pipe (not shown), to chamber 271 and thus to the cylinder. An inlet valve 32 is operated by finger 19 through a spring 40 engaging an abutment 38 on the valve stem 34 which is fluted to provide access from the supply to chamber 41. The release valve 44 having a stem 48 controls communication between chamber 27<1> and chamber 48 having atmosphere ports. A spring 62 may be connected to the casing and to the rod 14 to return the rod 14 and pedal to normal position. A bellows 37 extending between abutment 38 and the casing seals the chamber 41. A piston carried by the stem 34 and having sliding engagement with the casing, may replace the parts 37, 38. Movement of the rod 14 and finger 19 to the left unseats the valve 32 to supply compressed air to the brake cylinder and the consequent movement of the casing 4 tends to reseat the valve, this closing movement of the valve being accelerated by the cylinder pressure acting on the abutment 38 against the spring 40. If with the pedal and finger 19 held stationary, the pressure in the cylinder falls by leakage, the casing 4 moves slightly to the right to open the valve 32 and the valve stem moves to the left to assist the opening of the valve until the pressure is restored. Mechanical operation of the brakes may be effected by causing the shoulder 50 on the rod 14 to engage the casing 4. Return movement of the rod 14 causes the finger 19 to open the valve 44.