Hoopster retaining rings from Smalley Steel Ring Co., Lake Zurich, Ill., will stop components from sliding on shafts or keep them from sliding out of tubes. On shafts, a ring is expanded then allowed to snap into a machined groove. The ring protrudes from the shaft, providing a barrier so that properly sized toroidal components slipped onto the shaft cannot get past. The components need not have a sharp corner. Chamfered and radiused components also can’t get past the ring.
A Hoopster ring can also be installed inside tubes. A technician first compresses the ring, then positions it in a groove machined on the tube’s inside diameter, then lets the ring expand into that groove.
The rings are made of carbon steel (rated to 250°F) and 302 stainless steel (rated to 400°F), and come in standard sizes from 0.375 to 3.0 in. (10 to 76mm). The reusable rings can be installed and removed without the need for special tools.
Larger rings withstand substantial thrust loads. So the 0.375-in. ring withstands up to 1,052 N and the largest at 3.0in., can handle up to 21,168N. If the retained component exerts a force greater than the thrust rating, the groove can deform, letting the ring pop out of the groove.