| 摘要 |
1,227,298. Brake master cylinders. GENERAL MOTORS CORP. 2 May, 1969 [21 May, 1968], No. 22487/69. Heading F2F. A dual master cylinder 16 for an hydraulic brake system comprises a primary piston 32 operatively movable by a brake pedal 10 to pressurize fluid in a chamber 36, a secondary piston 34 movable by fluid under pressure in chamber 36 to pressurize fluid in a second chamber 38, and a pressure sensitive locking device to cause the pistons 32, 34 to move together until the pressure of the fluid in chamber 36 exceeds a predetermined value, the locking device being in the form of a pressure sensitive detent 106 mounted for movement transversely of the piston 32 to engage in an aperture in a spring retainer 48 which contacts the face of piston 34. Primary piston 32 has a cross-pin 102 which moves in slots 104 in spring retainer 48 so that movement of piston 32 relative to the part 48 is permitted and is normally sufficient to pressurize fluid in the chamber 36 to cause detent spring 112 to be compressed and move the detent inwardly. If however there is no pressure in chamber 36 force is mechanically transmitted from the piston 32 and spring retainer 48 to the piston 34. In a modification the spring retainer extends into an axial bore in piston 32 and the two pistons are locked by a V-shaped spring catch. In further modifications the spring retainer is formed in two telescoping parts or telescopes over the end of the primary piston, locking being by means of ratchet teeth or cam operated detents. |
