Speed change mechanism of automatic transmission

摘要

A first planetary gear unit is arranged to output a reduced speed rotation upon receiving a rotation from a prime mover. A speed change unit is arranged to which the reduced speed rotation is applied from the first planetary gear unit. The speed change unit is arranged at an opposite position of the prime mover with respect to the first planetary gear unit. An oil pump is arranged between the first planetary gear unit and the prime mover and driven by the prime mover. The oil pump includes a case to which the sun gear of the first planetary gear unit is connected. Friction elements are arranged to selectively engage and disengage rotation members of the first planetary gear unit and the speed change unit for achieving a desired speed position. A direct clutch is arranged to directly transmit the rotation from the prime mover to the speed change unit. The direct clutch includes an annular clutch pack which is concentrically disposed around the first planetary gear unit and a clutch piston which is arranged at an opposite position of the oil pump with respect to the first planetary gear unit.