Investigation of Roller Bearing Cage Pocket Lubrication and Friction

A test rig was designed and developed to assess the lubrication and friction of a single cylindrical roller and a conformal cage pocket. The roller was lubricated via oil bath in a sealed housing. Inner and outer bearing raceway pieces were fixed above and below the roller to mimic the internal geometry of an actual bearing. The cage pocket was made from transparent acrylic to look inside the cage and observe oil flow during operation. A six-axis load cell was used to measure the torque generated by the entire test rig with and without the cage pocket, and used to isolate the friction of the cage pocket. Experiments were conducted to investigate the effects of roller-pocket clearance, roller-race clearance, and roller oil submersion level at rest. Results suggest that roller bearing cage pocket friction increases with decreasing pocket clearance, increasing oil availability, and increasing operating speed. The oil was observed to coalesce into stable striations inside the cage pocket for many operating conditions. Striation width was observed to decrease with increasing speed, increasing pocket clearance, and decreasing oil availability. The striations were summarized by oil volume fraction inside the cage pocket, which decreased with increasing speed, decreasing pocket clearance and decreasing oil availability. The current results provide new information about oil behavior inside roller bearing cage pockets during operation, and an approach is presented to estimate roller bearing cage pocket friction.