Patent ID: 7998011

Claim:
A speed change apparatus, comprising: a first clutch having a first clutch drum, in which an annular clutch plate is spline-fitted to an inner peripheral surface of the first clutch drum, and a clutch piston formed with a spline on an inner peripheral surface of the clutch piston is provided to slide in an axial direction and press the clutch plate; and a second clutch having a second clutch drum, which is disposed in the clutch piston of the first clutch concentrically with the first clutch, and in which a spline is formed on inner and outer peripheral surfaces of the second clutch drum such that outer peripheral surface spline teeth form inner peripheral surface spline grooves, wherein the outer peripheral surface of the second clutch drum is spline-fitted to the inner peripheral surface of the clutch piston and an annular clutch plate is spline-fitted to the inner peripheral surface of the second clutch drum.