What is the effect of the 'Gap' width in a spiral retaining ring on its radial tension and ease of installation?

Spiral retaining rings are typically wound with zero gap (or a slight overlap). The radial tension $F_r$ required to expand the ring for installation is proportional to $\frac{E \cdot I}{R^2}$. A zero-gap design ensures 360-degree contact with the groove, which is essential for uniform load distribution. If a gap is introduced, the thrust capacity is reduced near the gap area. During installation, the ring is spiraled into the groove; a larger gap might make manual installation easier but reduces the 'cling' or grip the ring has on the groove bottom, which is vital for maintaining position under vibration or high-speed rotation.