AUTOMATIC TRANSMISSION

摘要

An automatic transmission (11), wherein an inner peripheral circular tube section (50a) and an outer peripheral circular tube section (50c) are integrated together by a flange-like section (50b), the automatic transmission is provided with a double circular tube-like section (50) forming a part of a clutch drum of a third clutch (C3), the inner peripheral circular tube section (50a) forms a first base bottom section on which a piston (43) of a fourth clutch (C4) slides, and the outer peripheral circular tube section (50c) forms a second base bottom section on which a piston (33) of the third clutch (C3) slides.  The front end (50d) of the outer peripheral circular tube section (50c) is extended until the front end (50d) penetrates through a clutch drum (42) of the fourth clutch (C4), the clutch drum (42) is prevented by a snap ring (51) from dislocating, and the clutch drum (42), which makes contact with and supports a cancel plate (34), is supported by the outer peripheral circular tube section (50c).  The clutch drum (42) is supported at a position closer to the outer periphery, so that, even if the clutch drum (42) is subjected to centrifugal hydraulic pressure of a cancel oil chamber (37), the clutch drum (42) is prevented from deforming.