The "A" Series pulleys are Adjustable Center Distance Drive type pulleys with a 5-30 horsepower capacity range. The "MA" Series pulleys are Fixed Center Distance Drive pulleys with a 5-125 horsepower capacity range. Both series use a unique patented Asymmetric Belt which allows the maintainance of belt alignment with single face movement pulleys on V-V drives. The automatic pulleys contain Hi-Lo's torque sensing mechanism to control belt tension with load requirement