A working unit includes a gear body disposed forwardly of a tubular member around which a wire is wound and having a rotational axis disposed substantially parallel to the tubular member, and a first gear and a second gear for transmitting rotation of a gear body to another gear body. The numbers of turns of wires, the size of a main shaft, and the size of a gear body, which are positioned forwardly of the tubular member, have no adverse effect on the manner in which a wire is wound around the tubular member. The wire can be wound around the tubular member over a wide region thereof for increasing the angular displacement of the gear body. The increased angular displacement of the gear body makes it possible to increase the angular displacement and rotational torque of the gear body.
