Official Answer
Answer
Under thrust load, all spiral rings exhibit some degree of 'dishing' as the radial wall $w$ twists. The allowable dish angle $\theta$ is typically limited to $6-10$ degrees. If $\theta$ exceeds this, the ring may lose its grip on the groove. The dish angle can be estimated by $\theta \approx \frac{M}{EI} L$, where $M$ is the moment caused by the thrust load offset. For heavy-duty applications, using a 'multiple-turn' ring (e.g., 3-turn vs 2-turn) increases the torsional stiffness and reduces the dish angle, thereby increasing the effective thrust capacity and safety margin against roll-out.
