Abstract: In a servomotor having a first diameter piston concentric to a second diameter piston for supplying a braking system with a first pressurizing force and a second pressurizing force in response to an operator input. A transfer valve has a first face and a second face which are located on opposite sides of a radial bore in the second piston to receive a first pressurizing force. The transfer valve has an axial passageway therethrough which communicates relief or reservoir pressure to the first and second faces of the transfer valve to provide a balance pressure force on the same. A spring holds the second face of the transfer valve against a seat to prevent communication of the first pressurizing force into the relief chamber.

Abstract: A control cylinder assembly for servo-steering systems including a fluid pressure circuit and steering shaft and an output shaft, in which a servo piston is supported during axial travel by axially spaced sleeves connected to a housing cover and the sleeves form circumposed fluid areas, and the piston forms opposed variable-volume operational areas, all of the areas being operatively connected in a fluid pressure circuit.

Abstract: A construction for the valving and road resistance reaction chambers utilizing the lower end of the steering spindle supported at the lower end of the steering housing by only two thrust bearings and utilizing a minimum of seals. The construction accomplishes the purpose of reducing friction in the steering of vehicles, especially important for heavy, high speed vehicles. The construction further realizes the advantage of requiring a minimum of space and an assembly of simple parts particularly advantageous in trucks having a tilting driver cabin.

Abstract: In a hydraulic brake booster, wherein a body, to which is coupled a master cylinder, is provided with a projecting portion extending outwardly towards the master cylinder; a power piston adapted to operate the piston of the master cylinder extends through the projecting portion to define a working chamber positioned on the side remote from the master cylinder; a pressure chamber, to which is introduced a pressure fluid from a pressure source, is provided in the middle portion of the body; and a first valve which is normally closed for controlling the communication of the pressure chamber with the working chamber and a second valve which is normally open for controlling the communication of the working chamber with a reservoir are operated by means of a valve stem member and an input shaft adapted to operate the valve stem member; the improvement in which a stop slidingly provided within the pressure chamber and adapted to receive pressure from the pressure chamber in the direction opposite to the moving direc

Abstract: In a control valve assembly of the kind set forth for vehicle braking systems a valve-operating member for operating first and second valves is guided to slide in a bore in a piston. The valve-operating member is adapted to permit the second valve to close and the first valve subsequently to open when the first piston is returned to an inoperative retracted position in response to the pressure of fluid remaining the pressure space when the applying force is relieved, the pressure space being defined between the first piston and a second piston.

Abstract: A hydraulic pressure fluid control system for controlling the displacements of a double-acting servo motor wherein a servo assisting valve mechanism comprises in addition to the control pistons for controlling and maintaining the pressures in the working chambers of the servo motor and the coil springs which place a predetermined minimum force to act on the pistons, spring retainers and further coil springs concentric and codirectional with the first coil springs arranged such that upon a movement of the input member of the system, a predetermined threshold force must be met before the input member directly couples with and controls the movements of the control pistons, the biasing of the coil springs and the further coil springs establishing the threshold value.

Abstract: The invention discloses a power-steering mechanism for an automotive vehicle, having a double acting actuator with two pressure chambers separated by an actuator piston. The actuator is connected both to the chassis of the vehicle and to a linkage associated with the direction controlling wheels of the vehicle. The pressure in the actuator chambers are controlled by a distributing valve operated by the steering wheel moved in either direction from a central, idle position. A reaction device adapted to create a return force biasing the steering wheel into its central position includes a circular cam eccentrically mounted on the rotating shaft of steering wheel and subjected to a thrust transmitted by a tappet. The tappet is projecting into a closed compartment to engage a reaction piston submitted to the pressure prevailing in a fluid accumulator. Two plungers are slidably mounted in the compartment and are submitted to the pressure prevailing in the actuator chambers.

Abstract: An oil-hydraulic servo-motor, usable with an automotive brake, including a control piston slidably extending through the rear end wall of a power cylinder in aligned opposite relation to an output piston therein and forming together with the cylinder end wall a spool-type control valve which is operable to energize and de-energize the power cylinder. The control piston is axially movable normally within definite limits under the operator's input, and abutment means provided to limit the extent of advancing movement of the control piston is rendered inoperable automatically upon failure of an associated oil pressure circuitry to enable the control piston to drive the output piston directly under the operator's input. The oil pressure circuitry may be formed in two independently operable systems. Major features include simplicity of the valving mechansim and hence of the entire structure of the servo-motor and a highly improved reliability in operation.

Abstract: The steering wheel controlled valve operator in a fluid power steering system, is mechanically held in a neutral position by centering springs associated with fluid pressure controlled reaction pistons yieldably resisting movement of the control valve by the valve operator. Check valves opened in response to suction pressure, conduct fluid in by-pass relation to the control valve between a servo motor chamber and a return fluid line, the control valve connecting both servo motor chambers to the return line in the neutral position.