GB559891A - Improvements in or relating to master cylinders for hydraulic transmission systems - Google Patents

Abstract

559,891. Telemotors. HYDRAULIC BRAKE CO. Aug. 6, 1942, No. 10995. Convention date, Oct. 13, 1941. [Class 69 (ii)] [Also in Group XXXIV] In hydraulic master cylinders for operating brakes and for other purposes, the piston is formed as a reservoir for supplying the system and contains open means for maintaining a light pressure normally in the system. Also the cylinder is provided with a chamber in which air that may accumulate in the system may collect and from which it may be allowed to escape. The master cylinder 12 connected at 36 to the pipe system contains a hollow piston comprising a tubular part 50, a head 56 upon which is seated the sealing cup 68, and a plug 72 screwed into the other end of the part 50. The cylinder is closed by a flexible boot 86 secured to an end collar 54 and to the operating rod 80 of the piston which is provided also with a sealing washer 74. The piston chamber 60 contains liquid and normally communicates with the forward part of the cylinder through a port 62 in the piston, ports 14, 16 in the cylinder and a chamber 20 formed by a member 22 fixed to the cylinder. The liquid in the chamber 60 and thus normally in the system is maintained under pressure by a piston 100 slidable in the main piston and loaded by a spring 108. When the main piston is returned by the spring 70 after an operation the tendency of the pressure in the cylinder chamber to fall causes liquid to flow from piston chamber 60 to the cylinder through passages 66 in the piston and past the cup 68. The liquid that subsequently returns from the pipe system under the action of the brake release springs, returns to the piston chamber 60 through the ports 16, 14 and chamber 20, re-compressing the spring 108. Air in the system collects upon and passes through a perforated screen 32 disposed in the chamber 20 and is permitted to escape by opening a bleeder valve 30 that normally closes this chamber.