PURPOSE: To facilitate the interchanging worm of a driving motor.

CONSTITUTION: A frame is provided with a lower frame 34 in which the body of a reducer 56 is fixed so that the driving motor 66 can be detached by releasing the flange connection and a main frame 36 covering the driving motor 66 projected from the lower frame 34 and rotatably supporting a hanging sheave. The main frame 36 is composed of the upper frame 38 and the intermediate frame 40 and the upper frame 38 and the lower frame 34 are detachably connected by the intermediate frame 40. And guide gibs 14-17 are arranged in the lower frame 34 and the upper frame 38 respectively. Further, the lower frame is provided with leg member 5 70, 72 holding nearly horizontally the lower frame 34 when the guide gibs 14-17 are placed down, in the state that the reducer 56 attached to the driving motor 66 is fixed.