Development of static tester for a compact-typed water lubricated hydrostatic bearings

Water-lubricated hydrostatic bearings, a type of plain bearings, achieve smooth rotation by forming a fluid film. While oil and air are commonly used as the working fluid in sliding bearings, water-lubricated bearings use water, which has lower viscosity than oil, as the working fluid, resulting in lower friction and enabling use in a clean environment. Most water-lubricated bearings have been developed for large bore sizes, and there are few examples of bearings for small bore sizes. Therefore, we developed a static characteristic tester that can evaluate the basic characteristics of water-lubricated hydrostatic bearings with slot restrictors. The static tester measures the displacement and load of the bearing casing, and the bearing is held in the casing by an O-ring. Because of the large load capacity and deformation of the O-ring in this test, care must be taken when calculating the eccentricity. Therefore, a torque meter was used to determine the contact between the shaft and bearing, and the eccentricity was calculated. In addition, a test machine was used to determine the load capacity from the load acting on the casing. Using this testing machine, the load capacities were measured for different slot clearances and bearing radius clearances, and the trends were investigated.