Patent ID: 7196444

Claim:
A stepping motor comprising: (a) a stator assembly; (b) a rotor assembly rotatably disposed inside the stator assembly, and including a rotary shaft rotatably supported by bearings, a sleeve fixedly attached onto the rotary shaft, at least one magnet disposed outside the sleeve, and a resin portion which is disposed between the sleeve and the at least one magnet, covers an outer circumferential surface and a part of one end surface of the sleeve, and which has a circular cylindrical hollow for accommodating a preloading mechanism; (c) the preloading mechanism disposed between the sleeve and one of the bearings, and including a coil spring, and a spring holder including an outer case shaped in a cup-like configuration and an inner case shaped in a cup-like configuration, and housing the coil spring, the spring holder containing a reinforced polyamide resin as a material; and (d) a washer member, the washer member having a high slidability and disposed between the preloading mechanism and the one of the bearings.