PURPOSE: To easily adjust the operation range of the rotary shaft by replacing a piece, which is detachably fitted, with a piece of optional size.

CONSTITUTION: A striker 9 rotates around the center axis of the rotary shaft 3 to strike the piece 11. When the rotary shaft 3 is further rotated clockwise after the striker 9 strikes on the piece 11, the striker 9 and piece 11 rotate around a fixed shaft 8 in one body. When the rotary shaft 3 is further rotated clockwise, the piece 11 strike on a stopper 13 and its movement is restricted, thereby stopping the rotation of the rotary shaft 3. When the rotary shaft 3 is rotated counterclockwise from its neutral state, the strike 9 and piece 11 strike each other to rotate in one body and strike on the stopper 12, thereby stopping the rotation of the rotary shaft 3. The operation range of the rotary shaft 3 is adjusted by replacing the piece 11 with a piece of optional sized.