Patent ID: 6637461
Filing Date: 2003-10-28
Classification: F15B,Y10T

Abstract:
A hydraulic apparatus comprising:a machine member; a body with a bore therein; a piston mechanically coupled to the machine member and located within the bore thereby defining a first control chamber and a second control chamber on opposite sides of the piston, the piston has a first end and a second end with a contoured surface there between wherein the contoured surface has oppositely tapering first and second tapered sections; a valve assembly having a valve element which moves to meter pressurized fluid selectively to the first and second control chambers to move the piston in opposite directions which moves the machine member, the valve assembly including an actuator which produces a first force that is applied to move the valve element; and a pilot pin which engages the piston and the valve assembly wherein movement of the pilot pin on the first and second tapered sections exerts a second force to the valve element.