AS50 One Way Clutch One Clutch AS50 is a one-way clutch, that is used for Overrunning, Indexing and Backstopping, this type is non-bearing supported, One way Bearing Sprag/Clutch Freewheel and also called as Backstops. AS50 is used in any application that requires one direction rotation, such as mining, hydraulic, textile, printing and washing machines, conveyor systems that carry products to a higher level should not be reversed because of gravity during any power shortage.