Short-Time Torque Investigations on DMA-Bearings

A new bearing torque rig capable of qualifying and analyzing bearing torque signals for large-bore high-precision bearings is described. The servomechanical subsystem responsible for torque definition within ± 5.9 × 10⁻⁴ Nm is also described. In addition to a space proven lubricant, two lubricants were tested in this rig: KG-80 oil and Polyfluoralkylalkyl polysiloxane grease. Tests were conducted on short-time basis in open air conditions. All three lubricants were tested in a 100 mm bore high-precision angular ball bearing, with and without ball retainer. The bearing was operated at various loads and speeds. Dependence on torque and Root Mean Square-torque as function of lubricant quantity are established. Data trend reveals the existence of a region of minimum torque for oil-retainer bearing configurations. Data also imply the feasability of using the two aforementioned lubricants and the full ball complement configuration in DMA-type applications.