In an automatic brake booster, a sleeve 18 constituting a valve mechanism 15 has a drive portion 50 disposed on the front side, a valve portion 51 forming a second valve seat 19, a mating portion 52 for mating with a valve seat portion when the drive portion is moved forward, and a conical spring 53 disposed between the drive portion and the valve seat portion and used for separating both members from each other. The conical spring is compressed during the normal braking operation so as to make ...

A load sensing proportioning valve for detecting the loading weight condition of a vehicle as represented by a distance between upper and lower positions of a spring. In this fashion, the fluid pressure acting on a rear wheel brake cylinder is controlled. The valve includes a push rod of a plunger; a loading spring coaxially mounted on the side of the push rod of the plunger, the load of the loading spring being applied to a housing during non-operation of a brake; a spacer spaced apart from the...

A method is provided for controlling an electric power pump type power steering system. In this method, there are provided a brushless motor (1) rotating, when a current is fed to coils, for driving a hydraulic pump of an automotive vehicle, thereby obtaining an assist power; a plurality of upper transistors (Q1) connected to the coils of the brushless motor with a control voltage being higher than a drive voltage of the brushless motor; a plurality of lower transistors (Q2) connected to a conne...

A rack-pinion type power steering apparatus includes a cylindrical stub shaft, a torsion bar, a pinion shaft, a rotor, and a sleeve. The stub shaft rotates in a steering body upon a steering operation. The torsion bar has one end fixed at one end of the stub shaft and extends through the stub shaft toward the other end of the stub shaft. The pinion shaft is pivotally connected to the other end of the torsion bar. The rotor is arranged to cover the torsion bar from the stub shaft along an extendi...

A plurality of axially extending ribs are formed in the inner periphery of a valve body at its front end for slidably supporting the outer peripheral surface of the output shaft at its rear end. With this arrangement, any dimensional error which may occur in the region of the ribs can be suppressed small during the manufacturing of the valve body if a diameter shrinkage occurs in the inner periphery thereof. Accordingly, when the rear end of the output shaft is slidably fitted into the ribs, the...

In accordance with the invention, a booster is not provided with a mechanism which transmits a braking reaction, and accordingly, a reaction cannot be transmitted to a brake pedal. On the other hand, a pseudo-reaction imparting means is provided to impart a pseudo-reaction which depends on an amount of depression of the brake pedal. The pseudo-reaction imparting means imparts a pseudo-reaction having a reduced rate of increase to the brake pedal when a travel of the brake pedal is small, and imp...

A cam case 23 is provided which swingably supports a cam ring 34 fitted to a rotor 33 having a vane 33a to form a pump chamber 36 from the outer surface such that the cam ring 34 is swingably supported by a swingable pin 35 disposed in the axial direction as a fulcrum, the cam case 23 serving as an intermediate body. Pump bodies are disposed on the two ends of the cam case in the axial direction. Moreover, a front body 21 and a rear body 22 for rotatively supporting a rotational shaft 40 of the ...

In a fluid pressure booster, an input rod 7 and a valve member 6 are stroked forward during the operation so as to cause a control valve to be switched over. The atmosphere is introduced into a working pressure chamber 30 via the control valve 41 and a power piston 19 then operates to make a negative pressure booster 1 produces an output from a output rod 13. As the atmosphere in the working pressure chamber 30 acts backward on a control piston 25 at this time, the valve member 6 will not be str...

An oil pump includes pump constituent elements, a pump body, and a driving shaft. The pump constituent elements define a pump chamber between a rotor and a cam ring that houses the rotor. The pump body is constituted by a front body and a rear body. The front body defines a housing space for housing the pump constituent elements. The driving shaft extends through and is axially supported by the front body to rotatably drive the rotor. An annular space is formed around the driving shaft in the fr...

A rubber damper is disposed between a valve plunger, which forms a valve mechanism of a brake booster, and a plate plunger. An air gap is defined around the outer and the inner periphery of the rubber damper to permit an elastic deformation of the rubber damper. When a brake pedal is further depressed under a servo balance condition, the valve plunger compresses the rubber damper, whereby it is driven forward. This arrangement allows a force of depression required when the brake pedal is further...