Answer
In high-speed rotating applications, centrifugal force acts on the mass of the retaining ring, tending to expand it radially and potentially lift it out of the groove. The limiting speed is $V = \sqrt{\frac{E \cdot I \cdot g}{w \cdot \rho \cdot R^4}}$, where $I$ is the moment of inertia, $w$ is the radial wall, and $\rho$ is the density. To combat this, 'Self-Locking' rings are designed with a tab and slot mechanism. The tab on the inner turn locks into a slot on the outer turn once the ring is seated in the groove. This mechanical interference prevents the ring from expanding due to centrifugal forces, allowing it to operate at RPMs far exceeding the theoretical limit of a standard spiral ring. This is essential for transmission components and high-speed electric motor rotors.
