Abstract: A transmission combining a plurality of planetary gear arrangements with a torque converter along with various clutching and braking elements provides a broad range of speed reductions with practically identical step ratios between shift ranges thereby efficiently transmitting torque from an input shaft to an output shaft over a broad range of output speeds.

Abstract: In a dual transmission system, the front transmission has a three-speed gearbox with a low, intermediate and a 1:1 input-to-output speed ratio coupled to a three-speed range unit to provide seven usable forward speeds. A converter lock-up clutch is used to provide direct mechanical drive in the upper six gears. The rear transmission has an identical three-speed range unit. An additional gear train is added to the rear transmission to provide four speeds. The additional very low speed is used in conjunction with the lowest speed of the front seven-speed transmission. Both transmissions are operated in torque converter drive in first gear only. When any of the speed ranges of the front range unit is used in conjunction with the low or intermediate input-to-output speed ratio of the front gearbox the same speed range of the rear transmission is coupled by a torque converter to the rear engine.