Variomatic

Variomatic is the continuously variable transmission (CVT) of the Dutch car manufacturer DAF, originally developed by Hub van Doorne.

“To solve a thorny weaving problem, the engineer developed a variator system that prevented the thread from cutting when starting the looms” , 1904 Fouillaron type G tonneau was equipped with a wooden Tonneau body and a De Dion 6 HP single-cylinder engine, the car did not exceed 25 km/h.

This vehicle has a very original gear transmission system with extendable pulleys, This invention, which he further developed and adapted to machine tools, was acquired by the Dutch car manufacturer DAF.

As a result, in the former Dutch annual backward driving world championship, the DAFs had to be put in a separate competition because no other car could keep up.

VDT continued the development of the CVT and introduced a push-belt system in the Ford Fiesta and Fiat Uno.

Although each belt could settle (independent of the other) into its optimum position, thus allowing for wheel speed variation, the system was slow to operate and depended on the pulleys being turned.

Low-speed handling in icy conditions was interesting as the system tended to drive the car forward against the influence of the steered wheels.

The modern CVT works according to the same principle of split pulleys allowing infinitely variable gear ratios.

A pair of conical pulleys, with a flat belt running between them. The lower pulley is formed from two separate movable cones. In the current configuration, the cones have been moved apart so the belt "falls" into space between them. By moving the cones closer, the belt is forced to ride higher on the sides of the cones, changing the pulley ratio.
Belt and pulleys of a Van Doorne transmission
Variomatic transmission and rear axle. The larger green drums on the left contain the vacuum mechanism that controls the variable pulleys. The rear wheels are driven by separate belts, eliminating the need for a differential .