Official Answer
Answer
For external rings, centrifugal force tends to expand the ring, potentially lifting it out of the groove. The maximum allowable speed $V$ in RPM is determined by $V = \sqrt{\frac{4 \cdot E \cdot g \cdot (d_n - d_g)}{0.0132 \cdot \rho \cdot D_m^5 \cdot (D_o - D_i)}}$, where $d_n$ is the neutral ring diameter and $d_g$ is the groove diameter. If the application speed exceeds this value, the ring must be designed with a 'self-locking' feature. This feature consists of a tab and a slot that mechanically prevents the ring from expanding beyond the groove diameter, allowing for significantly higher RPMs in high-speed rotating machinery like turbine shafts.
