Abstract: In a work cylinder (1) a ring (10) has been respectively inserted in the cross-sectional plane of the line connection (for example 6), which has a conduit (13) corresponding with the connection. At the highest point in the work cylinder (1) this conduit (13) is connected with the pressure chamber (for example 4) via an inlet opening (14). This arrangement has the advantage that the entrained air is carried along with the flow in the course of the movement of the piston (3). The air reaches the outside through the reservoir.

Abstract: A pressure relief valve (1) has a relief piston (5) for a large stream of oil and a precontrol piston (11) for a small stream of oil for influencing the point of actuation of the reliefing piston. Both pistons (5 and 11) are part of seat valves. The pressure relief valve is to be constructed so that the maximum pressure adjusted at high oil viscosity declines. In that way, the hydraulic apparatus containing the pressure relief valve is protected against overloading at low temperatures. For that purpose, the precontrol piston (11) has a bushing-shaped extension (26) that projects into a drilled hole (25) that is connected with an outlet (23). Furthermore, a ring surface (A1) is provided at the precontrol piston (11) that acts in the direction of opening. By means of the extension (26), a pressure-regulating section (27) that is dependent upon viscosity comes into play that generates a dynamic pressure that acts upon the ring surface (A1) when the oil is cold.

Abstract: A hydrostatic auxiliary power steering mechanism with load-dependent performance for controlling a variable displacement pump includes an orifice for generating a pressure difference. A control valve in a valve borehole contains a movable valve piston. Orifice is formed between the discharge opening cross-section of a pressure line into the valve borehole and a central spool land provided on valve piston and reveals a cross-section that can be altered as a function of the position of the control valve. The cross-section of orifice has its smallest value when the control valve is in the neutral middle position and can be made larger by adjusting the control valve in both directions.

Abstract: Hydrostatic auxiliary power steering devices transmit the steering power to the steered wheels via oil pressure. Such devices utilize a metering pump 5 and a steering valve 2 combined into a single unit. The metering pump distributes oil flow produced by a power steering pump 1 to a pressure operated steering power cylinder 8 under control of a steering valve 2 responsive to drive rotation of the vehicle steering wheel. The oil flow synchronizes the angle of rotation of the steering wheel with the angle of the lock of the wheels being steered. In hydrostatic systems there is a tendency to pressure oscillations. In the present invention these oscillations are minimized without occurring excessive pressure loss. The arrangement provides an inlet conduit 4 for steering, a damping valve 11 having a damping piston 12 centered by springs 13, 14 and closing off a branch conduit 6 which stops flow to the metering pump 5.

Abstract: A pair of flow restricting orifices regulate flow from a main engine driven pump through a control valve and steering wheel metering device to a servo motor in a vehicle steering system. Under emergency conditions, an additional flow restricting orifice connects the downstream side of one of the aforementioned pair of orifices to a flow dividing valve. The flow dividing valve connects a reserve pump in parallel with the main pump to augment the supply of pressure medium and sustain a minimal operational steering speed under control of the differential pressure across the other of the pair of orifices, which then dominates control of the supply of pressure medium to the servo motor through the additional flow restricting orifice while there is no flow through said one of the pair of orifices.

Abstract: Pressurized fluid from an engine driven pump is supplied to and exhausted from the opposed chambers of a hydrostatic power steering servomotor through control passages in a valve housing and in a rotatable valve body coupled through viscous liquid to a steering control shaft. A pressure signal from the pressurized chamber of the servomotor is supplied by the control passages to a valve between the pump and fluid reservoir to limit operating pressure as a function of servomotor loading.

Abstract: Separate branch conduits extend from a common pump to two fluid power operated systems. One of the branch conduits supplies a relatively low volume of fluid through a pilot flow conduit to a steering control valve in one of the systems to adjust its operating pressure when the steering control valve is displaced from its neutral position. The other branch conduit delivers pressurized fluid directly to the steering control valve on a priority basis. A pressure regulating valve connected between the other branch conduit and the pilot flow conduit isolates the steering system from a higher pressure in the other fluid power operated system and adjusts the operating pressure in the steering system to meet steering load demands.

Abstract: A hydrostatic steering system having a hand operated metering pump and steering control valve regulating and distributing fluid flow from a servo pump to a piston servomotor of the differential pressure surface type. A compensation valve disposed in the pressure line leading to one of the opposed chambers of the piston servomotor, is actuated by a differential pressure surface dimensioned to establish a constant ratio of pressures prevailing in the opposed pressure chambers in the neutral steering position while the metering pump is ineffective to produce any differential pressure. During active steering, the compensation valve is bypassed through a check valve.

Abstract: In a hydrostatic auxiliary power steering apparatus, a short-circuit passage of a control valve establishes a restricted flow path from a pump pressure line to a reservoir return line in the neutral position of the control valve wherein all other flow paths are blocked. A fixed flow restrictor in the pump pressure line conducts a continuous flow from one of two pumps connected to the pressure line for regulation of the fluid power steering circuit by the pressure drop across the flow restrictor. If one of the pumps is of the variable volume type, the pressure downstream of the flow restrictor is utilized to regulate pump flow adjustment. If fluid under operating pressure is supplied to both the fluid power steering circuit and another fluid operating circuit, a flow dividing valve controlled by the pressure differential across the flow restrictor distributes pressurized fluid between the two fluid circuits.

Abstract: A control valve for booster power steering has a back pressure check valve openable by pressure caused by wheel jolting, which check valve connects between a servopump pressure passage of the control valve through the inner bore of a valve sleeve operable within a housing bore to the inlet of a metering pump. Such valve ensures that the steering is "closed" under all circumstances including during steering to prevent pressure jolts being transmitted from the vehicle wheels due to road roughness. However, after completion of a steering operation high pressure can build up within the valve sleeve causing expansion of the valve sleeve and jamming within the housing bore, making operation difficult. Accordingly, a pressure limiting valve is provided connected to relieve the pressure within the valve sleeve bore.

Abstract: A flow control valve for a power steering system of the kind having a metering pump is provided with a leaf spring device stressed upon rotation of a hand steering wheel to operate a valve sleeve and the metering pump. The spring device provides a force for returning the valve sleeve to neutral position after a steering operation and comprises curved or arched springs between pressure plates. The convex sides are back-to-back between pressure plates and have curved ends supported on and shaped to slide on the pressure plates with minimum friction as the springs are compressed. The pressure plates are uniquely shaped in the central areas for providing flexibility to compensate for manufacturing inaccuracies.

Abstract: A differential pressure actuated valve is displaced from a spring-biased, stabilized position to a stabilized pump-changeover position in response to increasing pump pressure. The valve actuating pressure is varied in both directions of valve movement between the stabilized positions by variation of the restriction passage flow area through which the pressure differential is developed for actuating the valve.

Abstract: The invention provides a control valve having a valve piston and coacting valve sleeve for flow control in booster power steering systems of the kind having a servo steering pump and a metering pump, especially as used in motor vehicles having power steering cylinders. The valve piston and valve sleeve have novel rings and grooves that effect a throttling flow control as the valve piston is shifted in steering, which substantially reduces vibration or chatter of the valve, permits ready return to neutral of the valve piston and the danger of cavitation in the power cylinder precluded. The dimensioning of special rings on the piston coacting with rings in the valve sleeve produces the advantages of the invention particularly when the valve is controlling high pressures.

Abstract: An arrangement in the dropping of pressure in either chamber of a double acting booster steering servomotor is provided, such pressure drop starting at a predetermined point toward the end of travel of the servomotor piston in either direction. The invention is characterized by a respective bypass valve in each chamber, spring biased to closed position, and engageable by the piston, to be opened gradually. The piston force is exerted on the bypass valves through a respective spring so as to effect the gradual opening instead of the abrupt opening effected in the prior art. Opening of the bypass valves effects connections which shunt the servopump output to the system oil tank via a differential pressure valve as taught in Lang U.S. Pat. No. 3,878,763 to prevent strong mechanical stresses on the steering linkages at the ends of steering movement. Shunt control takes place through desirably small flow lines and bypass valves which heretofore have been found to produce undesirably abrupt operation.

Abstract: A feed pressure bypass valve means and actuator means primarily for a single acting servomotor, is provided having a unitary housing construction and an assembly of opposed springs wherein one spring biases a bypass valve to closed position and the other spring is compressed by the servometer piston to act in the opposite direction. The bypass valve is mounted externally of the servomotor as a separate and integral unit and has for its purposes to ensure maintaining a drop in feed pressure as the piston nears the end of its stroke. The provision of the spring compressed by the piston toward the end of the stroke ensures the opening and maintenance of opening of the bypass valve. There can be no instability of steering operation by virtue of the bypass valve closing and the striking of the servomotor cylinder wall by the piston is precluded.

Abstract: A valve device having a pressure operable valve piston, particularly for booster steering system, to selectively control pressure flow to a consumer device such as a hydraulic servomotor in order to permit use of a reserve pump in event of failure of a main pump. The valve in a neutral position combines the output of both pumps but is responsive to a first increase in the flow rate beyond a predetermined limit to shunt flow from the reserve pump to a sump. Upon further increase in the flow rate the valve piston moves to a position to also shunt part of the output from the main pump to a sump. Signal means is actuated by movement of the valve piston to apprise a vehicle driver that the steering system is operative.

Abstract: A valve device having a pressure operable valve piston, particularly for booster steering systems, to selectively control pressure flow to a consumer device such as a hydraulic servomotor in order to permit use of a reserve pump in event of failure of a main pump. The valve in a neutral position blocks the output of both pumps to a sump but is responsive to a first increase in flow rate beyond a predetermined limit to shunt flow from the reserve pump to a sump. Upon further increase in flow rate the valve piston moves to a position to also shunt part of the output from the main pump to a sump. Differential pressure acting on a valve piston effects shifting and means are provided to vary the differential pressure required to shift the valve piston so that a greater differential pressure is needed for the shifting of the valve piston for the partial shunting of the main pump output. Signal means is actuated by movement of the valve piston to apprise a vehicle driver that the valve device is operative.

Abstract: A motor vehicle servo steering system control for flow rate to the hydraulic steering cylinder mechanism utilizes a flow regulating bypass valve between the inlet and outlet of the system pump. A throttle bore device in the pump outlet is adjustable as to bore position to effect a variable operating pressure differential on the flow regulating valve bypass of the pump. The purpose of the arrangement is to effect as constant as possible a rate of flow to the steering servo cylinder mechanism at any given speed but with lowering of rate of flow when pump speed is increasing with engine speed. Accordingly, the invention provides a generally uniformly varying decrease in the amount of steering assist which a vehicle driver receives with increase in vehicle speed so as to convey a safer sense of road reaction at high speeds than would otherwise occur.