Patent ID: 7210292
Filing Date: 2007-05-01
Classification: E02F

Abstract:
1. A hydraulic system for a machine having a linkage system, comprising: a tank configured to hold a supply of fluid; at least one hydraulic actuator associated with the linkage system to affect movement of the linkage system, the at least one hydraulic actuator having a first pressure chamber and a second pressure chamber; four independent metering valves associated with the at least one hydraulic actuator, with one of the independent metering valves associated with the first pressure chamber and having a valve element movable between a first position at which fluid communication between the first pressure chamber and the tank is blocked, and a second position at which fluid is allowed to drain from the first pressure chamber to the tank; at least one sensor configured to sense a parameter indicative of a pressure in the second pressure chamber; and a controller in communication with the one independent metering valve and the sensor, the controller configured to move the valve element of the one independent metering valve in response to the sensed parameter indicative of a pressure in the second pressure chamber toward a position to minimize voiding in the second pressure chamber.