TFC Europe has enhanced its Smalley retaining ring range with the arrival of the ‘Hoopster’. The Hoopster retaining ring is suitable for applications where the depth of the groove is critical (thin wall cylinders, for example) since it only requires a shallow groove depth in order to perform successfully. Instead of edge-coiling the material, it is coiled on the flat to produce a ring that has an extremely low profile.
Unlike a conventional retaining ring or crclip, the retained component in a Hoopster retaining ring assembly may have a corner break. Thrust load is not sacrificed when the retained component has a broken corner because the moment arm* is negligible. The shallow groove associated with the Hoopster, in combination with the groove material, are the controlling factors in determining thrust capacity. The Hoopster does not twist when loaded, so pure thrust load based on shear strength of the material maximises the Hoopster’s load carrying capacity.
Groove deformation is by far the most common design limitation of most retaining rings. Unlike a conventional retaining ring or snap ring that fails by deforming or twisting, the Hoopster retaining ring shows superior strength from its low profile and mechanical advantage over traditional retaining rings under load. With a Hoopster there is no moment arm that twists the ring, causing premature failure as with a conventional retaining ring.
The shallow groove specification of a Hoopster makes the groove wall a critical specification, to ensure the function of the ring. To obtain maximum load capacity from a Hoopster retaining ring it is essential to have sharp corners on the groove. The maximum radius on the groove bottom should be no greater than 10% of the rings radius wall. Maintaining a sharp corner on the top of the groove is just as critical.
The Hoopster is suitable for medium or light loads and available as standard in Carbon and 302 Stainless Steel in a variety of sizes and can be offered in bespoke sizes with no extra tooling charges.
*Moment arm is a quantity used when calculating torque. Definition: The perpendicular distance from an axis to the line of action of a force.