Abstract: An automatic transmission including a fluid torque converter, an overdrive means and an auxiliary gear means, the overdrive means having a housing which presents a cylindrical outer peripheral surface concentric with the central axis of the transmission, the fluid torque converter and the auxiliary gear means having individual housings having a rear end portion and a front end portion, respectively, and presenting a cylindrical inner peripheral surface of substantially the same diameter as the aforementioned cylindrical outer peripheral surface and concentric with the central axis of the transmission whereby the transmission is assembled by engaging the aforementioned front and rear end portions over the overdrive housing.

Abstract: A device for controlling the speed shift operation of an automatic transmission including two change-over valves disposed in a passage transmitting the governor pressure to a servo chamber of a shift valve, the changing-over valves being actuated by the governor pressure and the throttle pressure so as to modify the governor pressure signal supplied to said shift valve thereby accomplishing a modification of a speed shift line to more favorably meet current exhaust gas purification requirements.

Abstract: A hydraulic transmission with a lock-up clutch comprising a housing which encloses a fluid transmission device like a torque converter and a mechanical lock-up clutch. The clutch includes a flexible disc which divides the chamber space confined by said housing into first and second chambers and may be selectively biased toward said first or second chamber due to a pressure difference generated between the two chambers. The flexible disc includes an opening through which a fluid circuit communicating through the first and second chambers in series is established to actuate, selectively either said torque converter or said lock-up clutch.

Abstract: A device for controlling a lock-up clutch incorporated in an automatic transmission together with a torque converter, wherein engagement and disengagement of the lock-up clutch are controlled by utilizing transitional variation characteristic of the oil pressure supplied to oil pressure servo means incorporated in the transmission.

Abstract: A driving system acting in conjunction with a motor vehicle having a torque convertor coaxially coupled to the output shaft of the engine, and transfer means having a driving gear coaxially coupled to the output shaft of the overdrive means and a driven gear coupled to its driving gear. Overdrive means having a planetary gear mechanism are coaxially coupled to the output shaft of the torque convertor, and include an output shaft coupled to the driving gear of the transfer means. An automatic transmission is coaxially coupled to the driven gear of the transfer means and includes a planetary mechanism and friction engaging means to provide the desired mode of operation. A differential gear having a driving gear coupled to the output shaft of the automatic transmission drives the motor vehicle. The automatic transmission is positioned below the overdrive means.

Abstract: A fluid pressure control system for a hydraulic transmission with a lock-up clutch including a lock-up clutch control valve which selectively supplies oil pressure for actuating the lock-up clutch. The lock-up clutch control valve being controlled by selective application of one of a plurality of servo fluid pressures for operating friction engaging means of a gear transmission, said selection of the servo fluid pressures being effected by a change-over valve composite in a changing-over manner.

Abstract: A hydraulic torque converter with a lock-up clutch wherein the cross section of a torus formed by an impeller, turbine and a stator is determined to satisfy that the ratio of its axial length L to its radial height H (L/H) is 0.64-0.80, the ratio of its inner diameter D.sub.i to its outer diameter D.sub.o (D.sub.i /D.sub.o) is 0.40-0.33 and the ratio of an annular flow passage area a at the exit of the impeller to a circular area A defined by the torus outer diameter (a/A) is 0.18-0.23.

Abstract: An overdrive mechanism disposed between a torque converter and change gear mechanism of an automatic transmission and responsive to the change gear mechanism. An input shaft to the change gear mechanism consists of two sections that are coupled by a clutch during normal power transmission. The driving section of the input shaft is connected to the turbine runner of the torque converter. A planetary gear train has a carrier operatively responsive to the pump impeller of the torque converter and a sun gear controlled by an overdrive brake. When the brake locks the sun gear against rotation during overdrive, the ring gear of the planetary gear train is rotated by the pump impeller and drives the second section of the input shaft through the clutch. The clutch is disengaged from the driving section of the input shaft during overdrive, thus by-passing power transmission from the turbine runner of the torque converter to the changer gear mechanism.