Automatic transmission system using drive belt and pulleys - is hydraulically-operated under control of electromagnetically operated valve

摘要

Conventional continuously variable transmission systems which incorporate pulleys and a drive belt, e.g. the 'Variomatic' system, use mechanical means to alter the distance between the conical inside faces of the pulleys and thus the radial distance at which the belt 'rides'. The present system uses hydraulic power supplied by a continuously operating pump and controlled by an electromagnetically operated valve. The valve has two pistons, one operated directly by the electromagnet and a second one operated by the action of the first via helical springs. This arrangement compensates for unwanted changes in fluid pressure caused by a spring-loaded over pressure return valve.