Mechanical ASD
There are two types of mechanical drives, variable pitch drives and traction drives.
Variable pitch drives are pulley and belt drives in which the pitch diameter of one or both pulleys can be adjusted.
Traction drives transmit power through metal rollers running against mating metal rollers. The input/output speed ratio is adjusted by moving the rollers to change the diameters of the contact path. Many different roller shapes and mechanical designs have been used..