Abstract: A hydraulic braking force multiplying device comprising an output member slidably fitted on a housing for actuating a piston of a hydraulic master cylinder, a working chamber defined between the housing and the output member, a valve seat member slidably fitted in an axial bore of the housing and rigidly secured to the output member, an input member slidably fitted in the axial bore and defining an intermediate chamber between the valve seat member, a valve member adapted to be actuated by the input member and having a valve portion of a valve mechanism for cooperating with a valve seat formed on the valve seat member, a pressure chamber permanently communicating with a source of pressure fluid being and being disposed in the housing and adapted to be connected with the intermediate chamber through the valve mechanism, a passage formed in the valve member for connecting the intermediate chamber with the working chamber, and a passage formed in the input member for connecting the intermediate chamber with a re

Abstract: In a power-operated hydraulic booster for a vehicle braking system pressurization of a power chamber in a housing on one side of a boost piston is controlled by an assembly of at least two separate spool parts which work in bores in the boost piston and the housing, and a boost chamber is defined in the housing between the power chamber and an output piston having an effective area less than that of the boost piston.

Abstract: A proportional force amplifier having a cylinder separated by a piston assembly into a pressure chamber, a control chamber and a reservoir chamber, a spool valve mounted for axial movement within a bore in said piston assembly to selectively connect the control chamber to either the pressure chamber or the reservoir chamber, the piston assembly moving in response to the change in pressure between the pressure chamber and the control chamber a distance equal to the distance of movement of the spool valve, the spool valve being connected for actuation by a resilient compensating rod and being pressure balanced.