Abstract

Abutment projections (54, 54) of a resin-made driver member (not shown) are inserted in the opposite end portions of a key groove (41) of a metal-made turnable member (4) in the circumferential direction. A key portion (B3) of a receiving cylindrical portion is inserted between the abutment projections (54, 54). The interval between the abutment projections (54, 54) in the circumferential direction is set to be slightly larger than the width of the key portion (B3). By doing so, when a transmission section is turned into an open position or a closed position, the abutment projections (54, 54) and the key portion (B3) are collided with each other, thereby generating a click sound. Moreover, since both the abutment projections (54, 54) and the key portion (B3) are formed of resin, they can be prevented from getting worn out soon.