AUTOMATIC TRANSMISSION

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. The one-way clutch has its outer race fixed to a flange, which is splined to the outer cylinder, and its inner race fixed to the flange of the first clutch and splined to the sun gear.