Abstract: An equalizing mechanism of a welding apparatus connects an apparatus body and a fixed bracket, and includes a fixed member on the fixed bracket, and a pressure shaft on an apparatus body close to a bottom face of the fixed member. A cutout is at a position facing the fixed member A movable member on the apparatus body accommodates the fixed member. A restrictive member located by side faces of the fixed member and the movable member restricts relative movement thereof to a direction parallel to the pressure shaft. A driven lever is supported by a front portion of the fixed member to abut on an inner front face of the movable member at one end and abut on the pressure shaft at an other end. A spring between a back portion of the fixed member and an inner back face of the movable member presses the two members to move away from each other.

Abstract: A drive unit of a pressure device, such as a welding gun, includes a piezoelectric type load cell adapted to be arranged in an easily attached and removed manner and to have relatively small capacity. The drive unit includes a through-hole 6, formed in a rotary shaft 5 of a drive motor 1, which is a drive source, and a pressure shaft 10, configured to be able to move with a part thereof being in the through-hole 6. The rotary shaft 5 is rotatably supported by the bearing 7, and the piezoelectric type load cell 17 is sandwiched between a preload striker plate 18, through which the pressure shaft 10 passes, and a preload setting striker plate 19, through which the pressure shaft 10 passes with a preload exerted on the load cell 17.