Abstract: A booster steering system has two pressure pumps for the booster cylinder, one of which is driven by the vehicle, with the wheels when the vehicle is rolling, and the other pump is driven by the vehicle engine. The vehicle driven pump is an emergency pump of non-variable displacement and can provide booster pressure flow to steer a vehicle off the road in an emergency should the engine driven pump fail. The engine driven pump is of variable displacement, normally maintained by an actuating means at zero stroke responsive to a pilot pressure from a steering control valve in neutral position with no steering pressure output. The vehicle driven pump normally provides the pressure output for steering. Accordingly, since most of the time the engine driven pump operates virtually pressurelessly there is no energy loss. When the vehicle is moving slowly in a tight curve a greater volume of output to the booster cylinder is needed and is provided by the engine driven variable displacement pump.

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 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: 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: Maximum angular displacement between the rotatable valve elements of a steering control valve is governed solely by the circular pitch of the piston gear associated with the metering gear pump in a hydrostatic fluid power steering system. A pair of fluid collecting manifolds in the control valve respectively communicate with the expanding and contracting pockets in the gear pump to form part of the flow paths between the gear pump and the fluid power steering motor.

Abstract: Axially spaced distributor grooves externally formed on a rotatable controller valve element conduct pressurized fluid to a servomotor in response to axial displacement of the valve element within a housing enclosing pressurized spaces to which opposite axial ends of the valve element are exposed. Flow of the pressurized fluid through the grooves is controlled by slide valve surfaces on the valve element axially between the pressurized spaces and the grooves.

Abstract: In a steering control valve device of the kind utilizing a metering pump and a torsional stress means for returning the flow control valve sleeve to a neutral position, there is provided a coupling sleeve between the manually operable steering spindle and the valve sleeve. Such coupling sleeve is for the purpose of providing an intermediate actuating member between the steering spindle and the valve sleeve to overcome errors in alignment and other disadvantages which can occur in conventional constructions where the steering spindle directly actuates the valve sleeve wherein rotation of the steering spindle effects axial shift of the valve sleeve for flow control purposes. The invention is particularly advantageous where the means of translating rotary motion of the steering spindle to axial movement of the valve sleeve is effected by threaded coaction.

Abstract: An auxiliary steering flow control device having known features of a rotatable steering spindle which initially effects axial shift of a valve sleeve through a torsional stressing device acting on a pair of compressibly arched leaf springs longitudinally disposed on the axis of the steering spindle and carried in a holder within the steering spindle. The leaf springs have contiguous contacting arched surfaces on the steering spindle axis and the arched configuration effects a back to back pretensing that augments the potential energy that can be stored in the springs, particularly in arched surface contiguity with each other.

Abstract: Axial flow paths are established between the ring gear of a rotatable fluid displacing device and the housing of an associated control valve by radial clearance passages formed in the ring gear and spacer in axial alignment with axial flow passages of the housing through which threaded fastener shanks extend to hold the ring gear, spacer and housing assembled. The gaps between the internal teeth of the ring gear are radially extended to receive the fasteners therethrough with a close assembly clearance along radially outer portions of the fastener shanks.

Abstract: A torsion rod is provided with articulated connections at opposite ends to transmit torque between a steering spindle and the universal shaft coupling of a pump rotor in a steering control valve. The end of the torsion rod coupled to the universal shaft is received in a bore that terminates close to the driven end of the universal shaft engaged with the pump rotor, the articulated connection to the torsion rod being located at said terminal end of the bore.

Abstract: The axial thrusts applied to two rotatable slide valve elements of a steering control valve assembly, are transmitted independently of each other through radially overlapping, anti-friction bearings to a common axial thrust absorbing surface. A thrust transmitting spacer positioned radially inwardly of one of the anti-friction bearings, extends axially between the other of the anti-friction bearings and the thrust absorbing surface.

Abstract: An annular gap between a valve shaft and the bore in a valve body of a steering control valve is dimensioned to accommodate relative eccentricity of parts and is sealed by a sealing gland having a rigid annular element rotatable with the valve shaft. The annular element is formed with recesses seating resilient sealing elements respectively engaging the valve shaft and an axial abutment surface of the valve body. The sealing elements are prestressed in radial directions and axial directions, respectively.

Abstract: Relatively dispaceable valve elements of a pressure controller for a vehicle steering system provided with radial bore type valve passages having two different flow area dimensions to regulate the pressure of fluid supplied to a servomotor in response to displacement of the valve elements to an operating position from a neutral position in which the valve passages establish a short circuit flow path between the pressure source and a low pressure outlet. Flow through the short circuit passages in the valve elements are blocked in sequence during displacement of the valve elements to the operating position by sequential closing of flow passages in one of the valve elements.

Abstract: A control valve assembly having relatively displaceable valve elements through which control passages establish fluid flow paths to a steering servomotor for supply of metered fluid to the pressurized side of the servomotor and exhaust of fluid from the contracting side to an internal low pressure space in the valve assembly. The control passages in the valve elements are protectively located between supply passages under full pump pressure to prevent loss of fluid as a result of leakage from the control passages.

Abstract: A differential drive arrangement interconnects positive displacement pumps with a manual actuating mechanism of an auxiliary fluid power steering system for vehicles to compensate for variations in fluid outflow from the pumps pressurizing two servomotors through two fluid operating circuits. Check valves in the two fluid circuits are arranged to maintain operation of only an appropriate one of the differentially driven pumps through one of the two fluid circuits when a pressure loss occurs in the other of the fluid circuits.

Abstract: The invention provides a pressure flow control valve for a booster steering system which effects an extended traverse of movement of concentric coacting valve sleeves relative to each other by a combined axial and rotary movement of the inner sleeve in order to smooth out the flow under control in pressurizing a servomotor, thus achieving an improved, or flatter, regulation curve characteristic, wherein a safe road reaction resistance to steering is effected, and wherein undesirable pressure fluctuations in the system are minimized as compared with prior art valving to reduce compressional vibration in the hydraulic system.

Abstract: A simplified overall hydraulic control system is provided for dual systems comprising a booster steering power cylinder and the power cylinder of an accessory of a work vehicle pressurized from a common engine driven hydraulic pump. The system utilizes conventionally constructed multiway valves for steering and accessory control and comprises flow dividing means effecting a constant minimum flow rate at all operational times for steering and variable flow rates for accessory power and additionally for steering dependent upon demand, essentially under vehicle operator control.A main steering flow to the steering control valve can connect with the minimum steering flow through a one way valve when steering is effected, less such flow as may be directed for accessory power by operation of the accessory control valve.

Abstract: Dual double acting servomotors hydraulically pressurized are provided wherein the pistons have shunt valve means actuatable at limit of movement of the pistons to shunt high pressure fluid at one side of the piston to the low pressure side of the piston then being exhausted. This results in relieving the stress otherwise effected against steering mechanism limit stops by continued application of high pressure feed to the pressurized chamber. The system encompasses steering control and shunt circuit valve means automatically actuated by differential pressures so as to direct pressure and exhaust flow selectively to and from the chambers of the respective cylinders from an engine driven pump and a manual metering pump for operating the steered wheels of heavy duty vehicles and which valve means effects bypassing of the engine driven pump pressure feed directly to one servomotor while feeding the combined pressures of that pump and the metering pump to the other.

Abstract: The invention provides a compact control valve for double acting steering system servomotors utilizing a housing and control valve therein with coacting lands and passage means effecting a transfer of fluid from one pressure chamber to the other of a single piston rod servomotor. Such transfer is in response to automatic straightening of the wheels of a vehicle by road contact after they have been turned to effect steering. In particular, since the servomotor pressure chambers are unequal in volume due to the bulk of the piston rod passing through only one chamber, some volume compensation for shunting of the fluid between chambers is required due to excess of fluid in going to the smaller volume chamber from the larger volume chamber, and deficit of fluid when transferring in the opposite direction.