Abstract: First and second hydraulic servo units operate respective frictional engagement elements in a transmission and each includes first and second cylinders, each having a side wall portion interposed between the two frictional engagement elements. The first cylinder has first outer and inner cylinder portions and the first hydraulic servo unit further includes a first piston having inner and outer cylindrical surfaces slidably supported by the first outer and first inner cylinder portions of the first cylinder for reciprocating axial motion into and out of engagement with one frictional engagement element. First return springs are arranged radially inward of the one frictional engagement element for returning the first piston.

Abstract: An automatic transmission for five forward speeds equipped with a main transmission mechanism and an auxiliary transmission mechanism. The auxiliary transmission mechanism includes a multi-disc clutch and a hydraulic servo therefor arranged in a first planetary gear set. The first planetary gear set includes a first ring gear connected to an output unit of the main transmission mechanism and a first carrier connected to an output shaft and further to a first sun gear through a multi-disc clutch and a hydraulic servo for the former. The hydraulic servo for the multi-disc clutch is connected to an integral casing through a band brake and is arranged around the outer circumference of the hydraulic servo for the multi-disc clutch.