A valve calibration system and method is disclosed for an electrohydraulic valve having upstream and downstream sides. A valve current controls the valve orifice size connecting the upstream and downstream sides. The calibration method includes opening the valve, stalling the system to prevent volume changes, and closing the valve with substantially equalized upstream and downstream pressures; then increasing upstream pressure, and finding a calibration current that provides a calibration orifice size through the valve by monitoring downstream pressure. Finding a calibration current can include stepping through valve control currents, sensing downstream pressures, and calculating step orifice sizes until the calculated step orifice size is greater than or equal to the calibration orifice size. Finding a calibration current can include performing a coarse calibration followed by a finer calibration. An offset can be calculated for a valve characteristic relating valve control current to valve orifice size.

The present invention in one or more embodiments provides a valve assembly which includes a valve shaft, and a valve head extending from the valve shaft, wherein the valve head defines first and second through-apertures extending along a width direction and a slot extending along a height direction, a longitudinal cross-section of the first and second through-apertures being partially received within the slot.

A hydraulic circuit is pressurized by a hydraulic pump driven by a power source in a machine. The hydraulic circuit is configured to use pressurized fluid from an accumulator to drive a hydraulic accessory when the hydraulic pump is inactive and the power source is shut down for fuel savings during idle operations. A valve may be configured to selectively supply pressurized hydraulic fluid to the accessory when the pump is inactive.