Abstract: A hydraulic booster has a boost piston (19) which receives the thrust of boost pressure generated in a boost chamber (15) to move the boost piston for urging a master piston (12) of a master cylinder in a brake applying direction. An input member (17) is relatively movably with respect to the boost piston (19). A pressure regulating device has an input directional control valve (22, 45) for allowing or cutting off communication between the boost chamber (15) and an auxiliary power source (14). An output directional control valve (24, 46) establishes or cuts off communication between the boost chamber (15) and a reserve tank (9). The boost piston (19), the input member (17) and the pressure regulating device are arranged inside a housing (1). An input member positioning device brings the rear end of the input member (17) into contact with a stop member (51) which is anchored to the housing (1), when a pedal force is zero for stopping a rearward movement of the input member.

Abstract: A throttle opening control actuator is provided between a throttle (2) which is regularly urged by a return spring (5) in a direction for decreasing its opening in order to regulate engine output of a vehicle and an acceleration pedal (1) which is coupled to the throttle (2) by a cable (7).

Abstract: A brake pressure control apparatus comprises a master cylinder (2), an auxiliary hydraulic power source (10), a booster (3), a comparator member (30), an inlet valve (28), a pressure raising member (31) and a limiter member (32). The comparator member (30) determines whether a fluid pressure in a fluid path connecting a boost chamber of the booster (3) with wheel brakes (8 and 9) is lower than a predetermined value. The inlet valve (28) cuts off flow of the fluid toward the wheel brakes (8 and 9) when it is determined that the fluid pressure in the fluid path connecting the boost chamber with the wheel brakes (8 and 9) is lower than the predetermined value. The pressure raising member (31) raises a brake pressure to be applied to the wheel brakes (8 and 9), based on a fluid pressure from the master cylinder. The limiter member (32) limits operation of the pressure raising member (31).

Abstract: A parallel proportioning valve for use in a dual braking system composed of a casing having a pair of parallel chambers, each of the chambers having a fluid inlet connected to a pressure source and a fluid pressure supply outlet. A fluid pressure responsive plunger is accommodated in each of the chambers with a valve seat provided in a fluid passage between the inlet and outlet. The pressure responsive plunger is adapted to open and close the valve seat.