Flat belt transmission with rotary actuator and integrated control system

A variable diameter pulley comprising two spaced, axially fixed sheaves, each having an inner and outer rotatable disc, said inner discs being rigidly interconnected and said outer discs being rigidly interconnected, means in said inner and outer discs defining oppositely angled, intersecting guideways, and drive elements having means for movably engaging said guideways at their intersections, said inner and outer rotatable discs including at least one pair of first and second chambers and means for exerting variable fluid pressure within said chambers, whereby, responsive to changes in the differential fluid pressure of said first and second chambers, said inner and outer discs rotate relative to each other for producing a radial shift of position of the intersections of said guideways and their associated drive elements, thereby changing the effective diameter of said pulley.