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.

Abstract: An automatic transmission includes: a connection member including an outer cylinder and an inner cylinder and defining a first annular space; a first annular piston arranged in the first annular space and defining a second annular space together with the inner cylinder; a second annular piston arranged in the second annular space; a spring retainer mounted on the inner cylinder in opposition to the second annular piston; a spring interposed, between the spring retainer and the second annular piston; a first clutch adapted to come into and out of engagement with a sun gear by the actuation of the first annular piston 72; a second clutch adapted to come into and out of engagement with an input shaft by the actuation of the second annular piston and left disengaged during forward running; a one-way clutch arranged adjacent to the first clutch and adapted to come into and out of engagement with the sun gear; and a brake interposed between the outer cylinder and the transmission casing.

Abstract: An automatic transmission has a rotational shaft with an axial through-hole. The shaft is supported by a case through bearings at opposite ends thereof. In the hole, a cup-type plug with holes is engaged with the shaft at one end thereof. A lubricating means is disposed in the case facing the holes for distributing a lubricating hydraulic fluid to bearings disposed at each end of the shaft.