Evaluation Of a High Speed, Light Load Phenomenon In Tilting-Pad Thrust Bearings

This paper discusses a newly found high speed, light load hydrodynamic tilting-pad thrust bearing phenomenon. The phenomenon was first witnessed on centrifugal compressors operating above 10,000 rpm. Testing results have shown that in high speed, light load applications, thrust bearing babbitt temperatures are much higher than expected at low load conditions, and then drop to expected levels as the thrust load is further increased. This behavior has been observed in flooded and directed lube type bearings as well as center- and offset-pivot designs, occurring at sliding velocities above 300 feet per second (fps) at the mean pad diameter and at thrust unit loads between zero and 100 pounds per square inch (psi).

Additionally, the authors discuss the initial anomalies encountered at an original equipment manufacturer's testing facility; extensive testing at the bearing manufacturer's facility to first reproduce the bearing behavior and then to introduce geometry modification to address the phenomenon. Finally, successful low load testing as well as high load testing is presented with the enhanced thrust bearing design.