Abstract: A power steering arrangement has a booster pressure cylinder shiftable on a piston fixed to the vehicle frame with steering rods connecting from the cylinder to the vehicle wheels. Valve means operable by a manually operated steering wheel pressurizes and exhausts the cylinder chambers at the ends of the piston. The valve means is carried in the piston for compactness and is actuated by a rack reciprocated by a pinion rotated in response to rotation of the manual steering wheel. The arrangement provides the advantage of compact assembly and rugged construction coupled with a minimum of oil leakage from the pressure cylinder. Inasmuch as the piston rod is fixed and has flow passages connecting to pump and tank, attachment of conduits for pressure and exhaust may be readily made. There are no moving conduit parts and tight sealing is achieved. The arrangement effects a desirable geometry of the steering mechanism.

Abstract: An improvement in apparatus for lifting an agricultural implement carried by a tractor provides for automatic rapid level adjustment of the implement relative to the terrain under control of a valve system which comprises a regulator valve controlling inlet flow to the pump responsive to a comparator valve carried by the implement. A continuous throtted flow from the regulating valve to the comparator valve is maintained at constant pressure tending to open a valve in the comparator while a sensor or feeler contacting the ground serves to effect a greater or lesser opposing force. A servo valve is provided which effects a back pressure acting together with feeler actuation. An equilibrium position of the valve determines the level to which the implement is changed, holding it constant on level ground until the feeler is actuated by encountering a rise or fall in the terrain. The construction provides for varying the elevation of an implement by either raising it or lowering it to meet rise or fall of terrain.

Abstract: A control valve for a hydraulic booster steering system provides gradual control of inlet flow to the system pump to complete cut off of output, or by throttling of inlet flow to effect a pilot stream through the pressure pump. This occurs in the neutral position of the control valve during straight ahead steering. Where flow through the pump intake feed means is thus impeded, the pump simply cavitates in a known manner and to be of a type which is suction regulated, having a check valve means at the pressure outlet side. The advantage of cutting off inlet flow to the pump during straight ahead steering, or at least throttling of such inlet flow by a constantly open throttle passage, is to save energy otherwise wasted in heating the fluid.

Abstract: The manual force transmitted by a hand steering wheel to a fluid power steering mechanism is opposed by a reaction pressure that varies with the manual force at a proportionality factor of the operating pressure in the steering servomotor. The proportionality factor determining the reaction pressure is changeable under control of a reaction adjusting device.

Abstract: A pair of inlet valves held closed in the neutral position of a valve actuator are opened under control of a valve operating force transmitted through a regulating spring in response to displacement of the valve actuator from the neutral position. The valve operating force applied is opposed by the pressure in a servomotor chamber to regulate the chamber pressure within a predetermined range above a limiting value of the valve operating force applied. Outlet valves are opened under a servomotor operating pressure higher than the pressure regulated by the inlet valves to control exhaust of fluid from the operating chambers.

Abstract: A piston valve construction effects leakage reduction in a control valve for hydraulic steering systems by reducing the wetted circumference of a portion of a piston valve collar with the use of radial recesses therein diverting a portion of flow therefrom to a groove of the piston valve which effects smoothing of turbulence of flow from said recesses followed by flow from said groove through a throttling gap to effect a laminar flow.

Abstract: For use in an agricultural machine which is automatically steered by sensing along a row of plants, a component of the automatic steering system, namely, a comparator system is disclosed herein which utilizes hydraulic signals from independent sensors and mechanically compares such signals with each other and with a mechanical feedback responsive to the degree of angularity of the steered wheels of the vehicle. The net result of the combination and construction of the comparator system is to provide automatic steering control for a small variation of steering of left and right steering courses, for example 2 to 5 degrees, wherein any large amount of deflection of the steering wheels that may be caused by the vehicle operator taking over the steering function will not affect the automatic operation of the comparator mechanism nor will the comparator mechanism have any response thereto.

Abstract: A fluid power assisted vehicle steering system which is switched between manual and automatic control by an operational mode selector, and switched from automatic to manual control without the intervention of the mode selector by an override action in response to operation of the manual steering control. Once switched to manual control, the steering system remains in the manual control mode of operation until switched by the mode selector to automatic control. Automatic control is also prevented until various safety conditions are satisfied.

Abstract: A power steering multi-way control valve is provided featuring means for effecting hydraulic blocking of a power cylinder so that the wheels of the vehicle will remain in the neutral or steered angle position even though the driver removes his hands from the steering wheel in order to operate other accessories. This is necessary for heavy work vehicles in the construction industry or other vehicles used in open terrain.

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: 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 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 fluid power assist type of vehicle steering system having a controlled servo motor assembly operated through a control circuit, and interconnected with the steering linkage, is provided with an auxiliary servo motor assembly through which pressure regulation is effected to prevent vibration otherwise amplified by feedback pressure signals. Differential pressure actuated pilot valves control the supply and return of pressurized fluid to and from the auxiliary servo motor assembly in response to differences between opposing pressures of the servo motor assemblies to regulate only the pressure chambers of the auxiliary servo motor assembly.

Abstract: A valve piston in an automotive power-steering system has a pair of inner peripheral grooves, defined by confronting lands of adjoining piston heads, normally communicating with the high-pressure side of an oil pump via symmetrical branch channels and with the low-pressure side of that pump via a common return channel. The piston also has a pair of outer peripheral grooves, normally cut off from the adjoining inner grooves, connected to opposite cylinder chambers of a hydraulic servomotor. The inner grooves communicate with a pair of axial piston bores receiving fixed or spring-loaded plungers for exerting a counteracting hydraulic pressure upon the piston upon a displacement thereof from its centered position, such displacement also opening the path from one branch channel via the corresponding inner groove and the adjoining outer groove to a corresponding servomotor chamber.

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.

Abstract: A steering shaft, linked with the dirigible wheels of an automotive vehicle and coupled with a hydraulic servomotor for rotation in either direction under the control of a main valve, has two abutments for alternately opening two normally closed ancillary valves in respective limiting positions of the shaft, these ancillary valves being inserted in branches of two feeder lines extending from the main valve to respective cylinder chambers of the servomotor. Either ancillary valve, when opened, connects one cylinder compartment of a differential valve to the feeder line then under low pressure, the other compartment of that differential valve being connected to a supply conduit whereby a pressure difference is created across a spring-loaded piston in that valve whose two compartments are interconnected by a bleeder line. The piston, upon being displaced by this pressure against its spring force, vents the supply conduit to the low-pressure side of the fluid source to arrest the servomotor.

Abstract: Piston type hydraulically balanced relief valves are disclosed except for one modification, utilizing pilot valves carried completely within the bodies of the relief valves or relief valve cartridges and wherein a single spring serves for closure of the relief valve and the respective pilot valve. All pilot valves are thus biased by a single spring primarily due to differential upstream and downstream areas both exposed to inlet pressure but with the upstream area larger and dominating. Accordingly, a single light biasing spring can suffice because of the reduced net opening force required, upon a predetermined rise in inlet pressure. The constructions afforded by such an arrangement are more compact than conventional pilot controlled relief valves wherein the relief and pilot valves are closed by separate and relatively heavy springs. Further, the advantage of the sensitivity of pilot controlled relief valves is realized together with effective damping and minimum control flow dependency.