Experimental Investigation of the Low Pass Filtering Effect of a Hydrostatic Bearing

Gears are used in numerous applications where mechanical power needs to be transmitted as in the powertrain of cars, buses and other vehicles. These gears can potentially be a significant source of high-frequency vibration and radiated noise in a vehicle, which can be both harmful and objectionable to any listeners in the vicinity. A proposed approach to addressing the gear mesh-frequency vibrations is to utilize the low pass filtering effect of a hydrostatic bearing in a gear mesh-frequency noise mitigation system. This paper describes an experimental investigation of the low pass filtering effect of a hydrostatic bearing using an experimental setup involving a widely available materials testing machine. By using the materials testing machine, appropriately sized hydrostatic bearing and externally pressurized fluid supply system, empirical data was collected that allowed the frequency response of the hydrostatic bearing to be determined. The frequency response of the hydrostatic bearing clearly shows a low pass filtering effect on the applied dynamic loads. Furthermore, changes to various system parameters had no effect on the frequency responses except at high driving frequency values. The observed low pass filtering effect of the hydrostatic bearing is potentially of great significance in any proposed gear mesh-frequency noise mitigation system since it prevents the mesh-frequency vibratory energy from being transmitted. Additionally, the experimental setup used provides a relatively simple setup for further studies on the dynamic behavior of the hydrostatic bearing.