Abstract: A hydraulic control system in which a pump for pressurized hydraulic fluid connects with a valve assembly having a valve element displaceable in a chamber to selectively direct fluid to a load driven by the hydraulic system. Surfaces on the end faces of the valve element are exposed to hydraulic pressure from a controller via electro-hydraulic solenoid valves. The surfaces of the valve element adjacent the end faces are undercut to establish a leakage flow path and the solenoid valves are selectively actuated to pressurize the end faces to a level below normal actuation of the valve element but high enough to cause fluid to return to a drain and thus increase the temperature of the hydraulic fluid in the system.

Abstract: A hydraulic control system in which a pump for pressurized hydraulic fluid connects with a valve assembly having a valve element displaceable in a chamber to selectively direct fluid to a load driven by the hydraulic system. Surfaces on the end faces of the valve element are exposed to hydraulic pressure from a controller via electro-hydraulic solenoid valves. The surfaces of the valve element adjacent the end faces are undercut to establish a leakage flow path and the solenoid valves are selectively actuated to pressurize the end faces to a level below normal actuation of the valve element but high enough to cause fluid to return to a drain and thus increase the temperature of the hydraulic fluid in the system.