Patent ID: 8241022

Claim:
A rotation-preventing member, comprising: an annular main body; a pair of first keys facing one another across an axis of the main body and extending to one side along an axial direction of the main body, the first keys having a pair of first surfaces extending along the axial direction and a radial direction of the main body; and a pair of second keys facing one another across an imaginary surface and extending to the same side to which the first keys extend or to the opposite side of the first keys along the axial direction, the imaginary surface being parallel to the first surfaces and including the axis, and the second keys having a pair of third surfaces orthogonal to the first surfaces and extending along the axial direction, of the first keys and the second keys, at least the first keys being provided with recesses opening onto end surfaces on the side toward which the keys extend, the end surfaces being top end surfaces extending orthogonal to the axial direction, the first keys being disposed entirely radially outward of an outermost circumferential edge of the annular main body.