GB501312A - Improvements in hydraulic operating systems - Google Patents

Abstract

501,312. Hydraulic transmission of power; clutches ; brakes. GENERAL MOTORS CORPORATION. March 25, 1938, No. 9165. Convention date, March 31, 1937. [Class 69 (ii)] [Also in Groups XXIV and XXXIV] A hydraulic master cylinder for operating brakes, clutches &c. comprises a seal through which the plunger reciprocates, a one-way valve opening from the reservoir to the high pressure side of the seal and a passage connecting the reservoir to the low pressure side of the seal, the plunger being constructed to connect the passage and the high pressure side of the seal when the plunger is retracted. The cylinder part 11 is secured by a bracket 13 and plate 17 to the too-board 21 of a vehicle. The plunger 29 slides through a rubber sleeve 35 bonded to a metal sleeve 33 having an end flange 37 secured by the cap 27 and abutting on a disc 57 between which and a spring seat 55 is a rubber seal 59 engaged by an expander 61 and spring 63. The sleeve 35 facilitates the axial alignment of the plunger. A rubber seal 41 is disposed between the sleeve and the cap 27. The plunger has a reduced end 87 that normally extends through the seal 59 as in Fig. 1, to connect the pressure cylinder proper 53 with a reservoir 49 through recesses 47 in the end of tube 33 and passage 65. A spring-urged one-way valve 79 is disposed between the reservoir and the cylinder 53. When the phmger is moved to apply pressure, the passage 65 from the reservoir to the cylinder 53 is cut off as in Fig. 2. During the return of the plunger, suction causes flow of liquid from the reservoir to the'cylinder through the valve 79, the excess liquid as it subsequently returns from the pipe-line 99 flowing back to the reservoir through the passage 65. As shown, there are two return springs arranged in series, an inner spring 91 seated at its ends respectively on the plunger end 87 and on a cage 83 and an outer spring 105 seated on the end 82 of the cage and on a valve 103 at the end of the cylinder. This arrangement of springs prevents an excessive spring pressure at the end of the stroke with a relatively short cylinder. In operation the spring 91 is deflected first. Rotation of the plunger is prevented by engagement of a pin 89 in a slot in the cage 83 or when a single spring is used in a slot in a tubular part 109, this part then serving as a guide for the plunger. The valve 103 comprises a metal cap seated on the cylinder end by the spring 105 and lifting to permit return of the liquid and containing a rubber element serving as an outlet valve. The Specification as open to inspection under Sect. 91 describes also the brake &c. operating cylinder and adjusting device described in Specification 495,748, [Group XXXIV]. This subject-matter does not appear in the Specification as accepted.