Abstract: A sleeve is covered on an outer peripheral surface of a shaft shaped part formed integrally with a support wall fixed to a casing of a transmission, to which sleeve a pair of seal rings are fitted putting a circumferential oil groove therebetween. A groove continuously formed in the outer peripheral surface and the tip end surface of the shaft shaped part is covered with the sleeve to form an oil passage structure. Part of oil supplied from an oil passage penetrating a main shaft to a discharge space for lubricating a bearing located at the tip end of the shaft shaped part flows into the oil passage structure and is further transferred to a space between the support wall and a clutch drum to lubricate the seal ring located on the side of the support wall from the outside.

Abstract: In an an automatic transmission, a low and reverse brake is arranged radially outward of a high clutch. The gripping plates of the low and reverse brake are arranged axially offset from the high clutch such that a diameter of the transmission is kept small. A piston of the low and reverse brake is associated with the gripping plates by way of arm members having cutout portions therein to allow a sensor, which penetrates the transmission casing in the vicinity of the low and reverse brake, access to a clutch drum of the high clutch so as to sense a rotation speed on an input shaft to which the high clutch is connected.