Patent ID: 7714247

Claim:
A weld cylinder comprising: a cylinder supporting a rod providing home, intermediate and work positions, the rod movable along an axis; a retract piston assembly arranged in the cylinder and movable between retract-return and retract-forward positions, the retract piston assembly providing a cushion chamber; a weld flange arranged in the retract piston assembly and movable between weld-return and weld-forward positions, the weld flange supporting the rod; a differential pressure valve supported by the retract piston assembly and axially movable relative thereto between closed and open positions, the differential pressure valve configured to regulate pressure in the cushion chamber; and an isolator valve supported by the retract piston assembly and axially movable relative thereto between closed and open positions, the isolator valve configured to maintain pressure in the cushion chamber with the retract piston assembly in a retract-return position, wherein the differential pressure valve and the isolator valve are concentric with one another.