ASNU30 One Way Clutch One Clutch ASNU30 = NFS30 ASNU30 is a one-way clutch. One way Sprag/Clutch Freewheel and also called as Backstops. ASNU30 is used in any applications 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.