The modular transmission uses only a pair of small and light hydraulic
machines of remarkably improved volumetric efficiency with pistons having
body portions substantially as long as the axial length of the respective
cylinders in which they reciprocate. The two hydraulic machines operate
in a closed loop, one being used as a pump driven by the vehicle's
engine, and the other used as a motor. Each machine has a fully
articulatable swash plate. By computer control, the angles of the swash
plates of the two machines are infinitely varied to provide an
appropriate optimum ratio of engine/wheel speed for all conditions from
start-up, city driving, hill climbing varied according to load and
steepness, and over-drive for highway. This complete vehicle operation is
attained while the vehicle's engine continues to operate at relatively
constant speeds and relatively low RPM.