Abstract: The neutral override circuit of this invention includes a variable displacement pump controlled by a servo fluidly connected to a displacement control that is biased to a neutral position. A charge pump is connected to the pump and the displacement control. A solenoid-operated neutral override brake control valve is connected to the charge circuit upstream of the displacement control valve and is normally biased to an open position. However, the solenoid urges the valve to a closed position in a response to a signal indicating that the brake has been released. In the open position, the valve dumps charge flow to the pump case until the supply pressure to the displacement control is inadequate to overcome the centering bias of the displacement control. The characteristics of the brake control valve can be set so that some minimum charge pressure and lubricating flow are still provided to the rotating elements of the pump.

Abstract: The neutral override circuit of this invention includes a variable displacement pump controlled by a servo fluidly connected to a displacement control that is biased to a neutral position. A charge pump is connected to the pump and the displacement control. A solenoid-operated neutral override brake control valve is connected to the charge circuit upstream of the displacement control valve and is normally biased to an open position. However, the solenoid urges the valve to a closed position in a response to a signal indicating that the brake has been released. In the open position, the valve dumps charge flow to the pump case until the supply pressure to the displacement control is inadequate to overcome the centering bias of the displacement control. The characteristics of the brake control valve can be set so that some minimum charge pressure and lubricating flow are still provided to the rotating elements of the pump.

Abstract: A method and apparatus for controlling an agricultural harvester having a cut crop receiving header coupled to a hydraulic cylinder. The header applies a force against the ground that is adjusted by applying pressure to the cylinder. A first proportional valve is fluidly coupled to the cylinder, and responds to a first input signal by increasing pressure in the cylinder to a setpoint value, when the pressure is less than the setpoint. A second proportional valve is also fluidly coupled to the cylinder, and responds to a second input signal by reducing pressure in the cylinder to the setpoint pressure value, when the pressure is greater than the setpoint. A pressure signal representing cylinder pressure is received. The difference between the measured pressure and the setpoint is used to compute the first and second input signals, which are transmitted to the valves.

Abstract: A safety device for a power takeoff shaft whereby the hydraulic control valve spool for controlling the power takeoff drive operates a switch in the engine starter circuit to disable the starter circuit when the power takeoff clutch is engaged.

Abstract: A load sensitive hydraulic system for operating auxiliary equipment on a vehicle with a priority flow control valve to provide priority pressure in operating a regenerative steering circuit of the hydraulic system. The regenerative hydraulic steering circuit provides load sensing and utilizes single source of pressurized fluid which responds to various loads in the hydraulic system. A priority valve assures that the steering demands are met before providing adequate pressure for all other auxiliary functions.

Abstract: A control valve operated by the steering wheel to selectively connect a variable displacement pump for operating a hydraulic cylinder in each of two directions to steer the vehicle. The hydrostatic system is regenerative in steering of the hydraulic cylinder in one direction since both sides of the hydraulic cylinder are connected to the high pressure input line in steering in one direction. A pilot line is connected to the valve output to sense load pressure and feed back to the compensator of the variable displacement pump to vary the displacement in response to load demands of the hydrostatic system.