Abstract: An electronic control device for hydraulic presses for making plywood and the like having electronic computer structure for developing a control for the desired hydraulic pressure having multiple input units on which at least the width, length and unit pressure may be set into the device for automatically effecting the calculation of the required hydraulic line pressure in order to apply the proper pressure upon the laminated plywood panels. The control device also anticipates maximum line pressure and cuts off the hydraulic pump(s) before the desired pressure is reached so that the inertia of the pump(s) and motor(s) will not increase the resultant line pressure above the predetermined desired pressure.

Abstract: A power steering pump flow and pressure control valve comprising a valve spool located on the high pressure side of the pump and on the upstream side of the vehicle steering gear. The valve includes a spool slidably situated in a valve chamber and a metering pin that is moved relative to the spool to either a first operating position or a second operating position. The metering pin registers with a flow control orifice located at one end of the valve chamber to provide a high flow or a low flow depending upon its operating position.

Abstract: A simple load sensitive hydraulic system having a variable displacement pump, a priority dependent work circuit, at least one secondary work circuit, priority means preferencing fluid flow to the priority dependent work circuit over the secondary work circuit, flow and pressure compensating means responsive to requirements of either work circuit for controlling displacement of the variable displacement pump and a relief valve which when overridden allows fluid flow to the secondary work circuit.

Abstract: A load responsive direction and flow control valve for use in fluid power load responsive system. The valve maintains a selected constant flow level for control of both positive and negative loads, irrespective of the change in the load magnitude or change in the fluid pressure, supplied to the valve. System is powered by a single fixed or variable volume pump. The direction flow control valve is equipped with a load responsive control which automatically regulates pump discharge pressure to maintain either a constant low pressure level or low pressure differential at the motor exhaust. The pump discharge pressure is either regulated by bypassing of excess flow to reservoir, or by a special load responsive control, which varies the pump displacement. Direction control valve may also be equipped with a control responsive to load pressure for controlling negative loads and an inlet pressure throttling control for simultaneous control of multiplicity of loads.

Abstract: A fluid drive assembly has a pump, a variable displacement motor, a fluid circuit connecting the pump to the motor, and an actuator device for controlling the displacement of the motor. The actuator device is movable between a first position at which the displacement of the motor is at a preselected maximum and a second position at which the displacement of the motor is at a preselected minimum. A control system for the fluid drive assembly includes a source of fluid at a first preselected pressure value. A valve device is connected to the source of fluid and to the actuator device for controlling the fluid flow therebetween and is movable between a first position at which the source of fluid is in communication with the actuator device and a second position at which the source of fluid is blocked from communication with the actuator device.

Abstract: A load responsive fluid power multiple load control system using load responsive direction and flow control valves in combination with pump control responding to highest system load. Each direction flow control valve is equipped with a load responsive positive load control which automatically regulates valve inlet pressure to maintain a relatively constant pressure differential between pump inlet pressure and load pressure at a first level and a load responsive negative load control which automatically regulates valve inlet pressure to maintain a relatively constant pressure differential between pump inlet pressure and load pressure at a second higher level. The load responsive control of each direction control valve blocks the pump flow to the motor while controlling negative load, providing the motor inlet with fluid from the motor exhaust.

Abstract: A hydraulic motor maintains its speed substantially constant in spite of changes of hydraulic fluid pressure and flow. The motor comprises a rotor to which hydraulic fluid is delivered through a nozzle arrangement from an inlet port and exhausted from the rotor to an exit port. A by-pass duct interconnects the passageway for the incoming fluid with the passageway for the outgoing fluid, to by-pass the rotor. A spring-loaded piston is situated in relation to the entrance to the by-pass duct so that when the incoming fluid pressure is relatively high the piston is retracted to expose the by-pass duct to permit some of the hydraulic fluid to by-pass the rotor, and when the fluid pressure and flow rate decrease, the spring moves the piston to close up the entrance to the by-pass duct to reduce or even stop the flow through the by-pass. A manual diverter valve is situated to divert incoming fluid away from the rotor so that all the fluid is diverted directly out of the motor housing.

Abstract: A hydraulic load-sensing system including a pump, a valve, a load-responsive actuator, and a hydraulic pressure unloading valve, all hydraulically connected together. The outlet of the pump is directed to both valves, and a sensing port and hydraulic line exist between the two valves for communicating the hydraulic load pressure to the unloading valve and thereby establishing the pump outlet pressure. A biasing member is included in the unloading valve, and therefore a constant hydraulic pressure drop is established across the valve supplying fluid to the load-responsive actuator, and a pressure relief valve limits the outlet pressure of the pump.

Abstract: The combined sensor and control comprises a flow sensor through which passes working hydraulic fluid delivered by a pump through a hydraulic power circuit to a hydraulically operated power mechanism which is subjected to variations in load. The sensor senses incipient changes in a preselected rate of flow of the working hydraulic fluid by detection of very slight changes in the differentials in the pressure of the working fluid at opposite sides of a restricting orifice through which the working fluid is constrained to pass. These differentials in pressure, or pressure drops, operate a pneumatic pressure control device by which pneumatic pressure supplied to an actuator through a circuit, isolated from the working hydraulic circuit, is controlled. The pressure control device causes the applied pneumatic pressure to be varied almost instantly in a manner analogous to the slight variations in the normal preselected differential in pressure across the orifice.

Abstract: A hydraulic governor valve coordinates the flow of crop material to a processing unit with the rate of processing of material therein. A gear driven pump is powered by the processing unit in direct relation therewith to drive a conveyor hydraulic motor. The flow responsive governor valve diverts flow to a reservoir when the processing unit is overloaded and to the conveyor motor otherwise to coordinate delivery of crop material with processing of same.

Abstract: Apparatus and method for controlling the velocity of an engine driven vehicle having a hydraulic system pump driven by the engine. Means are provided for controllably restricting the passage of fluid from the pump of the hydraulic system for controllably loading the engine and thereby controlling the velocity of the vehicle.

Abstract: A pump speed detecting device for diverse purposes in connection with various actuating devices disposed upon motor vehicles includes a pump, driven by a variable speed prime mover, for supplying fluid from a reservoir and discharging the same, at a flow rate proportional to the number of revolutions thereof, into a first conduit which is fluidically connected to a fluid motor. A flow control valve is fluidically connected to a first conduit so as to direct fluid from the first conduit into a second conduit which is in turn fluidically connected to the reservoir or the suction side of the pump. A first restriction is provided within the first conduit between the flow control valve and the fluid motor so as to control the flow control valve in response to the flow from the pump to the fluid motor. A second restriction is provided within the second conduit, and the actuating device is fluidically connected to the second conduit at a position just ahead of the orifice.

Abstract: A hydraulic safety circuit which keeps a hydraulic motor supplied with fluid during the interval when the motor coasts to a stop following shut off of its source of driving fluid. The circuit includes a conduit extending between the motor outlet and the motor inlet, with a check valve arrangement which shuts off normal fluid flow from the motor outlet to the fluid reservoir when the driving pump is shut off, and which instead diverts the fluid through the above noted conduit back to the motor inlet. This permits fluid to circulate through the motor as the motor coasts to a stop, preventing dry coasting and consequent possible burnout. The invention is particularly applicable to a wood chipper, where a heavy rotor (containing wood chipping blades) is connected to the motor and causes the motor to coast for an appreciable interval after the pump is shut off.