Abstract: An exemplary oil delivery system comprises a dual pump system configured for reducing the buildup of pressure by unloading one or both pumps, thus reducing the buildup of heat within the hydraulic system. The dual pump system is configured for delivering oil in combination to a single hydraulic system or to two completely separate hydraulic systems. In addition, the oil delivery system can also be configured to unload one or both of the pumping sections at a pre-determined speed to again limit the flow to any existing open centered hydraulic system. As a result, the oil delivery system recirculates oil back to the reservoir and/or the inlet to the pump in the absence of a buildup of pressure, and thus an absence in the buildup of heat to conserve energy.

Abstract: The present invention provides a proportional-flow electrohydraulic control which includes both an electrohydraulic valve (36) and an electronic control (382). The electronic control includes an offsetting circuit (622) and is effective to produce an effective driving voltage, for an electrical force-motor (52) of the electrohydraulic valve, that is pulse-width modulated and that is greater than a fixed proportionality to an input signal (410) by a manually adjustable offset voltage. The offset voltage may be adjusted to provide a null force that exactly balances a spring (129) which presses a valve spool (54) to an overlapped position; so that fluid flow is proportional to an input signal irrespective of the initial load of the spring. Or, the offset voltage may be adjusted to provide a basic flow voltage; and then the rate of fluid flow that is delivered by the valve is greater than a given proportionality to the input signal by a substantially constant rate of fluid flow.

Abstract: The present invention provides an electrohydraulic control, which includes both an electrohydraulic valve (36) and an electronic control (382). The electronic control includes an offsetting circuit (622) and is effective to produce an effective driving voltage, for an electrical force-motor (52) of the electrohydraulic valve, that is pulse-width-modulated and that is greater than a fixed proportionality to an input signal (410) by a manually adjustable offset voltage. The offset voltage may be adjusted to produce a null force that exactly balances a spring (129) which presses the valve spool (54) to an overlapped position; so that fluid flow is proportional to an input signal irrespective of the initial load of the spring.