Patent ID: 8663020

Claim:
A shaft, comprising: an outer peripheral surface; an inner peripheral surface; an oil flow passage that is formed in the shaft and is defined by the inner peripheral surface; a large inner-diameter portion having a first inner diameter; a small inner-diameter portion adjoining the large inner-diameter portion in one direction along an axial direction of the shaft, and having a second inner diameter smaller than the first inner diameter; and a through hole extending from an inner peripheral surface of the large inner-diameter portion to the outer peripheral surface of the shaft, wherein the small inner-diameter portion is formed by bending radially inward an extending portion, which extends in the one direction from the large inner-diameter portion, the extending portion is a thin portion having a radial thickness smaller than that of the large inner-diameter portion, and the small inner-diameter portion is formed by bending the thin portion radially inward.