PURPOSE: To make it possible to smoothly take-in and -out electric equipment by preventing scuffing between a movable bearing and a threaded rod screwed to the movable bearing.

CONSTITUTION: A square nut is loosely fitted to a square hole in a central part of a movable bearing 15, and a threaded rod 10A is screwed to this square nut. Guide bars 19A and 19B are penetrated into a slide bearing inserted into the front and rear ends of the movable bearing 15, and the upper and lower ends of these guide rods 19A and 19B are fixed to lateral frames 1c and 1d of a box body 1. The movable bearing 15 is fixed to a bearing plate 16, and a groove 13 connecting the upper portion of the front end to the lower portion of the rear end is formed in this bearing plate 16. Rollers 7 are projected out at both the side faces of a vacuum circuit breaker 3 which is taken in/out by pressing the rollers 7 forward and backward at the groove 13 of the bearing plate 16 driven up and down by a motor 20.