The Oil Bath Lubrication of Ball and Roller Bearings at High Speed

Abstract

In pursuit of information concerning the performances of the high speed rolling bearings operating under oil bath 1ubrication and light load, measurements of bearing temperature rise and friction coefficient have been made using radial ball and roller bearings of 40mm bore with pressed cages. As the lubricant, spindle oil or turbine oil is applied and the level of oil bath is always kept in somewhat lower than the centre of rolling element which is placed at the lowest position in the bearing. The experimental results of bearings, operated at a rotating speed up to 24, 000 rpm for the ball bearing and 16, 000 rpm for the roller bearing, indicate that the bearing temperature rise and friction coefficient increase proportionally to the rotating speed of bearing. From the fact that bearings had been operated securely under such high speed, it may be convinced that, under light load, the oil bath lubrication can be applied for a speed far higher than the speed which is adopted customarily under the limitation of dn-value of 250, 000. Furthermore, at such a high speed, the friction coefficients of bearings under oil bath lubrication take the values nearly twice as the values lubricated with minimum oil, and such differences depend on the hydrodynamic friction losses owing to churning oil.