Official Answer
Answer
In rotating assemblies like automatic transmissions, centrifugal oil pressure can build up behind the retaining ring. If the ring does not have sufficient 'drainage' (i.e., the gap between the ring ends), the pressure can force the ring out of the groove. Design engineers must ensure the ring's radial wall does not completely block oil flow-through paths. Additionally, the centrifugal expansion of the ring itself (see Q62) must be modeled alongside the hydraulic pressure to ensure the net radial force remains inward.
