Patent ID: 7301118

Claim:
A welding gun assembly comprising: a housing that defines a first chamber and a second chamber; a first piston moveably disposed in said first chamber so as to divide said first chamber into a first pressure chamber and a first return chamber; a second piston moveably disposed in said second chamber; an intensifying rod movable at least partially into said first chamber due to movement of said second piston; a pressure sensor in fluid communication with only one of the first pressure chamber and the first return chamber to thereby detect pressure therein; and a controller operable to change pressure within the first and second chambers based on the pressure detected by the pressure sensor such that the controller increases pressure within said first chamber up to approximately a predetermined extension pressure while said intensifying rod is disposed outside of said first chamber, and such that the controller increases pressure within said second chamber to thereby move said intensifying rod at least partially into said first chamber to thereby increase pressure within said first chamber above the predetermined extension pressure.