Abstract: A multiple disk clutch includes a clutch drum having an interior surface with a plurality of spline grooves, a servo piston, a clutch plate with splines engaged within the spline grooves, and a cushion plate, with splines engaged within the spline grooves, arranged between the clutch plate and the servo piston. The splines of the clutch plate and those of the cushion plate are engaged within different spline grooves so that the splines of the clutch plates and those of the cushion plate do not contact each other when the clutch is engaged by a load imposed by operation of the piston.

Abstract: An internally toothed member is shown suitable for use as a clutch drum in an automatic transmission. The internally toothed member has the shape of a cup with an open end and a central axis. The cup-shaped member has first internal teeth extending in the axial direction and second internal teeth extending further toward the open end of the member than the first internal teeth. The internal teeth are each formed on an inner circumferential surface of the cup-shaped member in each of a plurality of locations spaced in the circumferential direction. Also, a groove for receiving a snap ring is formed in the second internal teeth closer to the open end than end faces of the first internal teeth facing the open end. Because the first and second internal teeth are formed projecting radially inward, they do not lower the rigidity of the internally toothed member.