GB975252A - - Google Patents

Abstract

975,252. Fluid - pressure brake control. AUTOMOTIVE PRODUCTS CO. Ltd. March 13, 1961 [May 24, 1960], No. 18324/60. Heading F2F. [Also in Division G3] In a liquid pressure braking system a deceleration controlled servo 16 closes a shut-off valve 29 between the master cylinder 13 and the wheel cylinders 12 and also moves a pressure balanced plunger 32 to increase the volume of the system connected to the wheel cylinders when the valve 29 is shut. Under normal braking liquid pressure passes from the master cylinder 13 past the stop valve 29, held off a seating 27 by a pin 33, forming the end of a double plunger assembly 32, 37, biased by a spring 45 of a vacuum servo unit 16, through passage 41 to the wheel cylinders 12. The liquid pressure is also transmitted through a passage 40 to a chamber surrounding the plunger 34 and impinges on the annular area of a head portion 35 which is equal in area to the plunger 32, thus balancing the plungers. On excessive deceleration the deceleration responsive means 18 closes the chamber 47 to vacuum from engine inlet manifold 21 and opens the chamber to atmosphere; the chamber 44 being open to vacuum, the plungers 37 and 32 are moved to the left by diaphragm 43 and the valve 29 is seated by a spring 31 to shut off the liquid pressure to the wheel cylinders. As the plunger 32 moves the volume of the chamber at its right-hand end increases and decreases the wheel cylinder pressure to release the brakes. The deceleration responsive means 18 comprises a double-acting valve 17 which connects a passage 68, connected to the chamber 47, to vacuum through passage 70 under normal conditions and to atmosphere through chamber 69 when a flywheel 52 runs on in relation to the casing 51 and causes camming balls to run up in radial grooves in cam plates 53, 55. The casing 51 is belt driven from a transmission shaft 20 and drives the flywheel 52 through the camming balls and a friction washer 61, the cam-plate 55 being resiliently supported and driven by a dished spring 56. In a modified deceleration responsive means a double-beat valve 17 closes one seating before opening the other, and the flywheel is driven frictionally through a sleeve driven from the casing.