What is the 'Walk-Out' failure mode in spiral retaining rings and how can it be prevented?

'Walk-out' occurs when the retaining ring expands or contracts enough to lose its seat in the groove and is pushed out axially by the retained part. This is common in high-speed rotating applications where centrifugal force expands an external ring. It can also occur under high vibration (fretting) or if the ring is undersized for the groove. To prevent walk-out: 1) Use a 'Self-Locking' ring design; 2) Ensure the groove is deep enough (at least $1.5 · t$); 3) Verify that the ring has sufficient 'cling' by checking that its free diameter is significantly different from the groove diameter; 4) Minimize the radius on the retained part to prevent the 'wedge' effect.