JPS4949334B1 - - Google Patents

Abstract

1,223,568. Fluid pressure actuators. GIRLING Ltd. Nov.26, 1968 [Dec.22, 1967], No.58495/67. Heading F1P. [Also in Division F2] In a fluid pressure actuated motor, particularly for a dual braking system (Division F2), at least two pistons 18, 20 are coupled together in tandem and work in separate cylinder spaces formed in outer cylindrical wall portions, 10, 64, the outer cylindrical wall portion 64 being encircled over a part of its axial length by the outer cylindrical wall portion 10 and the cylinder spaces are separated by a fixed wall 12. The pistons 18, 20 are connected by a stem portion 29 forming part of a pressure member 30 which passes through the fixed dividing wall 12 between the chambers 22 and 24 which are open to atmosphere and the stem abuts against a thrust pad 34 welded to the back face of the piston 18. A force transmitting element 44 extends from the piston 18 and has connected thereto a force transmitting push rod 42 which extends through a central aperture 40 in an end wall 14 of the motor casing. In operation, when compressed air is fed into the chambers 26 and 28 a pressure differential is created across the pistons 18 and 20 which move in opposition to a return spring 52 to displace the push rod 42 outwardly to actuate the vehicle brakes. When used in conjunction with a dual braking system the inlets 56 and 58 are each connected to separate pressure sources such that failure of one source of supply will not cause a complete failure. Should the supply to the rear cylinder fail, the forward piston 18 can move forwardly on its own leaving the rear piston behind and if the supply to the forward cylinder fails the rear piston can move forwardly pushing the forward piston ahead of it. Instead of being operated by compressed air the motor can be modified so as to be vacuum operated or hydraulically operated.