Abstract: A frictional engagement device for an automatic transmission includes a tubular case, a friction member on one side that is supported on the case, a friction member on the other side that is supported on a rotary element, an annular piston having a pressing portion that presses the friction members toward one axial side with a thrust force from a pressure receiving portion that defines an annular hydraulic chamber between it and the case, and plural return springs for urging the piston toward the other axial side. The piston has a first pressure receiving section where the pressing portion is cut out over a predetermined angular range, and a second pressure receiving section other than the first pressure receiving section. An urging force of the return springs per unit angular range of the first pressure receiving section is greater than an urging force of the return springs per unit angular range of the second pressure receiving section.

Abstract: A first planetary gear unit PR and a clutch C3 for outputting reduced speed rotation are located on one axial side of a second planetary gear unit PU, and a clutch C1 for connecting and disconnecting an input shaft 2 to/from a sun gear S2 and a clutch C2 for connecting and disconnecting the input shaft 2 input to/from a carrier CR2 are located on the other axial side of the second planetary gear unit PU. An output mechanism is located between the first and second planetary gear units. As compared with a drivetrain wherein the clutch C1 or clutch C2 is located between the two planetary gear units, the two planetary gear units can be located closer together, and a transmitting member that transmits the reduced speed rotation can be made shorter. Further, compared to a drivetrain wherein the clutches C1, C2, C3 are located together on one axial side, the oil supply to the hydraulic servos can be simplified.

Abstract: A planetary gear unit PR and a clutch C3 for outputting reduced speed rotation and a clutch C1 for connecting and disconnecting input of rotation of an input shaft to a sun gear S2 are located on one axial side of a planetary gear unit PU, and a clutch C2 for connecting and disconnecting input of rotation of the input shaft to the carrier CR2 is located on the axially opposite of the planetary gear unit PU. By doing so, as compared to a case wherein, for example, a clutch C1 and clutch C2 are both located between a pair of planetary gear units PR and PU, the planetary gear units PR and PU can be located more closely together, and the member that transmits the reduced speed rotation from planetary gear unit PR to planetary gear unit PU can be made shorter. Further, compared to the case wherein, for example, the clutches C1, C2, C3 are located on one axial side of the planetary gear units, the construction of the oil lines is simplified.

Abstract: A second planetary gear unit PR and a clutch C1 for outputting reduced speed rotation are located on one axial side of a first planetary gear unit PU, with an output unit located therebetween. A clutch C2 which connects/disconnects an input shaft 2 to/from a sun gear S2 of the planetary gear unit PU and a clutch C3 connects and disconnects the input shaft to/from a carrier CR2 of the planetary gear unit are on the other axial side of the first planetary gear unit PU. Compared with a transmission wherein a clutch C2 or clutch C3 is located between the second planetary gear unit PR and the planetary gear unit PU, the second planetary gear unit PR and the first planetary gear unit PU can be located closer together, and a member which transmits the reduced speed rotation can be made shorter. Further, compared to the case wherein, for example, the clutches C1, C2, C3 are located together on one axial side, oil supply to their servos is simplified.

Abstract: A planetary gear unit PR and a clutch C3 for outputting reduced speed rotation and a clutch C1 for connecting and disconnecting input of rotation of an input shaft to a sun gear S2 are located on one axial side of a planetary gear unit PU, and a clutch C2 for connecting and disconnecting input of rotation of the input shaft to the carrier CR2 is located on the axially opposite of the planetary gear unit PU. By doing so, as compared to a case wherein, for example, a clutch C1 and clutch C2 are both located between a pair of planetary gear units PR and PU, the planetary gear units PR and PU can be located more closely together, and the member that transmits the reduced speed rotation from planetary gear unit PR to planetary gear unit PU can be made shorter. Further, compared to the case wherein, for example, the clutches C1, C2, C3 are located on one axial side of the planetary gear units, the construction of the oil lines is simplified.

Abstract: A first planetary gear unit PR and a clutch C3 for outputting reduced speed rotation are located on one axial side of a second planetary gear unit PU, and a clutch C1 for connecting and disconnecting an input shaft 2 to/from a sun gear S2 and a clutch C2 for connecting and disconnecting the input shaft 2 input to/from a carrier CR2 are located on the other axial side of the second planetary gear unit PU. An output mechanism is located between the first and second planetary gear units. As compared with a drivetrain wherein the clutch C1 or clutch C2 is located between the two planetary gear units, the two planetary gear units can be located closer together, and a transmitting member that transmits the reduced speed rotation can be made shorter. Further, compared to a drivetrain wherein the clutches C1, C2, C3 are located together on one axial side, the oil supply to the hydraulic servos can be simplified.

Abstract: A second planetary gear unit PR and a clutch C1 for outputting reduced speed rotation are located on one axial side of a first planetary gear unit PU, with an output unit located therebetween. A clutch C2 which connects/disconnects an input shaft 2 to/from a sun gear S2 of the planetary gear unit PU and a clutch C3 connects and disconnects the input shaft to/from a carrier CR2 of the planetary gear unit are on the other axial side of the first planetary gear unit PU. Compared with a transmission wherein a clutch C2 or clutch C3 is located between the second planetary gear unit PR and the planetary gear unit PU, the second planetary gear unit PR and the first planetary gear unit PU can be located closer together, and a member which transmits the reduced speed rotation can be made shorter. Further, compared to the case wherein, for example, the clutches C1, C2, C3 are located together on one axial side, oil supply to their servos is simplified.