Patent attributes
A clutch device for an automatic transmission includes a clutch drum, first and second frictional coupling elements, both supported by the clutch drum, a first piston axially movably disposed radially outwardly of the clutch drum and operating to couple the first frictional coupling elements, and a second piston axially movably disposed radially inwardly of the clutch drum and operating to couple the second frictional coupling elements. The clutch drum includes an inner drum portion welded on a rotary shaft, and an outer drum portion welded on the inner drum portion and supporting the first and second frictional coupling elements. The first piston is axially slidable relative to the inner drum portion. The second piston is axially slidable relative to the rotary shaft. And, a welded portion of the rotary shaft and the inner drum portion, and a welded portion of the inner drum portion and the outer drum portion, are radially spaced in a predetermined distance and concentric with each other.
