Abstract: A variable speed transmission (1) is disclosed which has a torque converter (6) at the input of both a fixed transmission (4) which is used for low vehicle speeds and a variable transmission (5) which is used for medium and high vehicle speeds. The variable transmission (5) has a variator (11) which may be of the belt and pulley, hydraulic or electric types. The variable transmission (5) is more efficient than heretofore because power is split within the variable transmission (5) by a power split differential (9) between the variator (11) and a main power output shaft (3). Thus, the variator (11) is only called upon to handle a portion of the power when the variable transmission (5) is in operation. Thus, power losses in the variator (11) are substantially reduced.

Abstract: A variable speed transmission assembly comprises a variator (3) connected between main power input and output shafts (1 and 4), a power split differential gear assembly (2) splits power from the input between the output and the variator and the variator output is connected to a ratio spread differential (5), one output of which is connected to the main power output shaft, the other output also feeding the variator input, so that the variator handles less than one half of the total power and, the variator input runs at a speed which is inversely proportional to the output speed. In this way, the variator is better able to handle its power throughput.