Patent ID: 8629369

Claim:
A weld cylinder comprising: a cylinder supporting a rod providing home, intermediate and work positions; a retract piston assembly arranged in the cylinder and movable between retract-return and retract-forward positions; a weld flange arranged in the retract piston assembly and movable between weld-return and weld-forward positions, the weld flange supporting the rod; retract-return, weld-return positions, retract-forward and weld-forward ports pressurized to provide the corresponding retract-return, weld-return positions, retract-forward and weld-forward positions, wherein the home position corresponds to the retract-return and weld-return positions with the non-corresponding ports vented, the intermediate position corresponds to the retract-forward and weld-return positions with the non-corresponding ports vented, the work position corresponds to the retract-forward and weld-forward positions with the non-corresponding ports vented; a differential pressure valve fluidly connected to the weld-return and retract-forward ports in at least one of the intermediate and work positions to actuate the differential pressure valve between closed and open positions; and an isolator valve configured to cooperate with the differential pressure valve to create a passage and exhaust fluid from a cushion chamber through the passage.