OPERATING FORCE REINFORCING DEVICE

摘要

PURPOSE:To obtain the accurate boosting effect of a booster even in the case of the pressure of pressure source for the booster is lowered or insufficient by interposing the booster and a change-over valve between a master cylinder and slave cylinders, and devising the structure of the change-over valve. CONSTITUTION:A booster A is interposed at a front line hydraulic circuit 18 for connecting a master cylinder 11 to front wheel cylinders 19. The booster A is provided with a valve 27 for allowing the communication between the master cylinder 11 and wheel cylinders 19 in the illustrated original position of a booster piston 26, also allowing the flow from the master cylinder 11 side to the wheel cylinder 19 side in the moving position of the booster piston 26 and impeding the contraflow. A change-over valve B is provided with a piston 44 moved by a vacuum motor 49 into a position where a plate 49b is brought into contact with a housing 49d when the pressure of pressure source 14 is over the set value and into an illustrated position (reset position) when the pressure of the pressure source 14 is below the set value.