GB1147061A - Improvements in and relating to vehicle brake actuators - Google Patents

Abstract

1,147,061. Vehicle brake actuators. YORK TRAILER CO. Ltd. 26 April, 1666 [29 April, 1965; 15 Sept., 1965], Nos. 18125/65 and 39458/65. Heading F2F. A vehicle brake actuator comprises a first chamber 1, which is sub-divided into three chamber portions 2, 4 and 6 by two diaphragms and or pistons 8 and 10 operatively connected to a brake actuating rod 14, the chamber portions 4 and 6 having connections 24 and 26 to service and auxiliary air supply lines respectively, and a second chamber 12, which incorporates a third piston or diaphragm 30, also operatively connected to the brake actuating rod, said third piston or diaphragm normally being retained in the brake release position against the bias of a brake applying spring 33 acting on one side of said third piston or diaphragm by pressure fluid supplied through an emergency third line connection 44 acting on the other side of said piston or diaphragm. On service application of the brakes air is supplied from a reservoir (not shown) on the vehicle, e.g. a trailer, through a relay valve or valves to chamber portion 4 to actuate the brakes. On failure of the service supply line, the brakes are operated by air supply through the auxiliary line to actuate the diaphragm 10. If the air reservoir to both the service and auxiliary supply lines fails, the second chamber 12 becomes depressurized, and the brakes are applied by the spring 33. Similarly, if the pressure in the second chamber is deliberately leaked by opening a parking valve (not shown), the brakes are again spring- applied. In an alternative embodiment, instead of mounting the actuator on a vehicle bracket by means of bolts at the front end 18 of the first chamber, the actuator is mounted by bolts 50 extending from the end wall of the second chamber, the brake rod 14 in this embodiment extending from the first chamber, through the piston 30 of the second chamber, and out through the said end wall. The piston of the second chamber is coupled to the brake rod by a sealing sleeve 20 slidably passing through said end wall.