Patent ID: 7409825

Claim:
A hydraulic system with component failure protection comprising: a source of fluid including a pump and a tank; a hydraulic actuator having a first chamber; a control valve assembly remote from the hydraulic actuator and connected to the source, the control valve assembly having a first workport and controlling flow of fluid between the source and the first workport; an isolation valve adjacent the hydraulic actuator and connected to the first chamber and to the first workport, the isolation valve having a valve element wherein pressure in the first chamber acts on the valve element tending to open the isolation valve, wherein the isolation valve has a first state that provides a path between from the first chamber to the first workport, and has a second state in which fluid can flow only in a direction from the first workport to the first chamber; and a pressure relief valve that responds to pressure in the first chamber exceeding a given level by relieving pressure acting on the valve element thereby enabling the isolation valve to open in response to pressure in the first chamber.