| 摘要 |
A first retaining ring (43) is disposed between a first outer circumferential groove (31a) provided in an outer circumferential surface of a radial bearing (30), and an inner circumferential groove (8b) of a cylindrical portion 8a of a transmission case (8). A ring piece (31b) is provided with an outer ring (31) of the radial bearing (30). The ring piece (31b) protrudes outward in a radial direction and is in contact with an output gear side end surface of the cylindrical portion (8a) in the axial direction. A return spring (44) that urges the piston (56) in a direction opposite to a direction in which the pressure is applied by the piston (56). The return spring (56) is retained in the axial direction by a second retaining ring (45). The second retaining ring (45) is locked in a second outer circumferential groove (31c) of the ring piece (31b). According to the invention, the outer ring (31) of the radial bearing (30) has a ring piece (31b) which supports a thrust force of the outer gear (7), thereby relieving the thrust force acting on the first retaining ring (43). In addition, the ring piece (31b) (instead of the casing in the prior art) contains a groove for the second retaining ring (45). Thereby, as compared with the prior art, abrasion of the locking grooves in the transmission casing (made of aluminum alloy) due to the harder retaining rings (made of ferrous metal) is prevented. |
