Abstract: An intermediate storage vessel (26) has a cylinder container (26a), a piston (28) provided in the cylinder container (26a) so as to be slidable in a reciprocating manner, and an inpour hole portion (32) and a discharge hole portion (34) that are opened in a cylinder chamber (30) where the piston (28) slides. The inpour hole portion (32) is provided above the discharge hole portion (34). An insulation cover (70) is provided so as to cover the intermediate storage vessel (26) and an insulation mechanism (20), and the cover is removable from the insulation mechanism (20) side.

Abstract: A motor-driven welding gun has a servomotor for displacing a movable electrode tip toward and away from a fixed electrode tip. The servomotor has a motor housing with a copper pipe which is inserted therein when the motor housing is cast. The copper pipe provides a coolant passage in the motor housing for supplying a coolant therethrough. When the coolant passage is supplied with the coolant, the motor housing is forcibly cooled, reducing the amount of heat generated by the servomotor.