GB418219A - Improvements in master cylinders for hydraulic power transmission systems - Google Patents

Abstract

418,219. Hydraulic transmission of power. HYDRAULIC BRAKE CO., 84, West Hancock Avenue, Detroit, Michigan, U.S.A. April 18, 1933, No. 11395. Convention date, April 22, 1932. [Class 69 (ii).] In a master cylinder device for hydraulic brakes and other hydraulic transmission systems comprising high- and low-pressure cylinders, the lowpressure piston is rendered ineffective by a valve when a predetermined pressure is established in the system and the high-pressure cylinder then discharges into the system through the lowpressure cylinder. The high-pressure piston 17, Fig. 1, is connected to the low-pressure piston 19 within which slides a piston 29 carrying a valve 31 normally seated over a hole in the cup-washer 33 by a spring 28. The reservoir 9 normally communicates through port 21 with high-pressure cylinder 6 thence through passages 22, 23, 24, 26 with the cylinder 7 below the piston 19. The interior of the piston 19 communicates with the reservoir through passages 42, 43, 44. A valve 40, such as described in Specification 384,724, is provided for normally retaining in the pipe lines 41 a pressure somewhat above atmospheric. When the pistons are moved downwardly by rod 18, the piston 19 forces liquid into the pipe lines 41, liquid being at the same time drawn into the increasing space between the pistons 19, 17 from the reservoir through grooves 44 and past the cup-washer 20. When the pressure below the piston 19 and valve 31 is sufficient to overcome the spring 28, the valve rises and by uncovering the hole in the washer 33 renders the piston 19 ineffective and permits the piston 17 to force liquid into the pipe lines through the cylinder 7. In a modification, Fig. 2, the valve 71 is slidable against the spring 72 in a cylinder 68 which is normally supported by the spring 69. The piston 53 is normally supported from piston 54 by spring 55. The passage 64 through piston 54 is thus normally open as is also a passage 61, 57 from the reservoir to the space between the pistons. During the initial stage of operation these passages are closed by the cylinder 68 abutting on the two pistons, but when the pressure below piston 54 acting on the valve 71 is sufficient to overcome the spring 72, the valve rises, reopening the passage 64 thus rendering the piston 54 inoperative.