GB603675A - Improvements in or relating to actuating means for vehicle brakes - Google Patents

Abstract

603,675. Hydraulically - operated brakes. ROBERTS, G. P. Oct. 27, 1945, No. 28458. [Class 103 (i)] Vehicle brake - operating means comprises as a unit a master cylinder connected by pipe lines to wheel cylinders of front brakes and a slave cylinder, the piston of which is connected by mechanical means to rear brakes, the unit embodying also a cam or equivalent engaging the mechanical means, whereby the rear brakes may be operated by a hand lever. Means are provided whereby the master piston operates the rear brakes mechanically if the fluidpressure fails and to ensure the hydraulic operation of the front brakes if the mechanical transmission to the rear brakes fails. A master cylinder 11, the piston 13 of which is operated by a pedal and a rod 14 is connected by a port 21 to a slave cylinder 12, the piston 25 of which is connected by a rod 28 having a head 34 engageable with lost-motion with a plunger 35 slidable in an extension 18 of the cylinders 11, 12 and connected by a cable 36 to the rear brakes. The pressure chamber of the slave cylinder 12 into which the port 21 opens is connected to the pipe-lines of the front brakes and by a passage through the piston controlled by a non-return valve 31 to the forward part of the cylinder, thence to a reservoir. Thus, when the master piston 13 is operated, liquid is forced into the slave cylinder to the wheel cylinders of the front brakes and the slave piston is also operated by the hydraulic pressure to operate the rear brakes through the cable 36. Racks 32 formed in the pistons 13, 25 mesh with a pinion 33 slidable in a slot in the casting which forms the cylinders, whereby the piston 25 is operated mechanically by the piston 13 if the hydraulic system fails and if the mechanical transmission to the rear brakes should fail, the forward movement of the piston 25 is arrested by a stop 49 engaging in a slot 50 in the piston, so that the front brakes may still be applied. Operation of the rear brakes can also be effected by a hand-lever connected by a Bowden cable 43 and a chain 42 to a sprocket 41 on a shaft 40 which carries a cam 39 engaging a follower 38 on the plunger 35. A spiral spring 46 acting on the sprocket 41 urges the cam 39 to its normal position against a stop 47.