Effectiveness of a Preventive Bearing Design for Retainer Instability

Retainer instability (RI) is a detrimental phenomenon in rolling bearings that can cause torque fluctuation, torque increase, abnormal noise, vibration, and, in severe cases, bearing failure. This study establishes a preventive retainer design based on the occurrence mechanism of RI, specifically by suppressing the continuous tangential frictional force acting along the retainer’s circular orbit. For practical design implementation, we introduced the concept of an accessible area, which visualizes the relationship between the retainer’s motion direction and the frictional force. RI is likely to occur when the accessible area is circular, because the contact force acting on its outer boundary tends to align with the tangential direction of the retainer orbit. To disrupt this condition, a preventive retainer was developed by combining large and small pockets, resulting in a distorted, non‑circular (diamond‑like) accessible area. Operation tests were conducted on retainers with various large–small pocket patterns. The results showed that RI occurred for designs with lower distortion levels of the accessible area, whereas it did not occur for those with higher distortion levels, demonstrating that the distortion of the accessible area is an effective factor in suppressing RI.