Patent ID: 7237470

Claim:
A fluid power unit comprising: an inlet and an outlet; a cylinder; a piston slidable in the cylinder, the piston dividing the cylinder into a retract side and an extend side; a two-position control valve; the control valve having a spool, a first pilot and a second pilot; the position of the spool responsive to the first and second pilots; a retract poppet valve in the retract side, and an extend poppet valve in the extend side; the retract and extend poppet valves being biased to a closed position; the retract poppet valve being in a fluid path between the retract side and the control valve; the extend poppet valve being in a fluid path between the extend side and the control valve; so that, when the spool is in its first position and the retract poppet valve is closed, the spool completes a fluid path: from the inlet to the extend side; and, from the retract side to the outlet; and, when the retract side poppet valve opens it completes a fluid path from the first pilot to the retract side, causing the spool to shift to its second position, so that the spool completes a fluid path: from the inlet to the retract side; and, from the outlet to the extend side; and, when the extend side poppet valve opens it completes a fluid path from the second pilot to the extend side, causing the spool to shift to its first position; and, a first orifice in the path from the inlet to the first pilot, and a second orifice in the path from the inlet to the second pilot, so that the first and second orifices transmit inlet pressure to their respective first and second pilots when the respective retract and extend poppet valves are closed.