GB389930A - Improvements in hydraulic control gear for the brakes of vehicles and like purposes - Google Patents

Abstract

389,930. Hydraulic apparatus for brakes and other purposes. RUBURY, J. M., Little East, Convent Hill, Bocking, Braintree, Essex. Dec. 23, 1931, No. 35536. [Class 103 (i).] In hydraulic transmission apparatus for brakes and other purposes such as described in Specification 365,069, comprising a piston c operated by a lever e or the like to apply pressure to a second piston d which forces liquid into the pipes leading to the brake &c. actuating cylinders and in which ports h for supplying liquid from a reservoir a to the space between the pistons are normally uncovered by the piston c, a spring i disposed between the pistons is adapted to transmit sufficient pressure from the piston c to the piston d to prevent substantial hydraulic pressure building up in the space between the pistons until the cup-packing f of the piston c has passed the ports h. Damage to the cuppacking f by exposure to high fluid-pressure while covering the ports h is thus avoided. As shown, the piston d has a spring-loaded non-return valve past which liquid is forced if the piston d reaches its end position before the brakes are applied or the liquid may pass through a hole in the piston and along the outside of the cup-packing of the piston. To prevent excessive pressure in the pipe lines, a non-return valve k may be provided to allow return of the liquid. The piston d may be of smaller or as shown, of larger diameter than the piston c. In the latter case a boosting effect is produced on piston d during the first part of the travel, that is, until the brakes are applied.