Official Answer
Answer
Centrifugal lift-off failure is diagnosed by observing evidence that the retaining ring moved radially out of its groove during operation. This often leaves 'scuff marks' on the housing bore or damage to the shaft components that were supposed to be retained. In some cases, the ring may partially reseat itself as the motor slows down, making the failure mysterious. However, meticulous inspection will usually reveal a 'wear pattern' on the back side of the ring and a deformed groove edge where the ring was partially pulled out. To prevent this, the designer must calculate the 'Lift-off RPM' and ensure it is at least $125\%$ of the motor's 'Redline' speed, or use a self-locking spiral ring design.
