Water-Lubricated Soft-Rubber Bearings

Abstract

Abstract Rubber bearings lubricated with water are found to have remarkably low coefficients of friction and to give excellent service under many conditions. The softness of the rubber makes these bearings stand up in the presence of sand and grit, and it also makes the laws of lubrication governing these bearings differ from the classical laws worked out by Reynolds and others for cylindrical metal bearings. This paper gives a comparison of the frictions of rubber and metal bearings lubricated with water at various loads and speeds. Metal bearings have the lower static coefficient of friction, but the coefficient of running friction is usually lower for rubber bearings. The difference in favor of rubber bearings increases as the load increases, provided the shaft is smooth and the load is applied after the shaft gets up to speed. Rubber bearings have been tested at loads up to 850 lb. per sq. in. Rubber bearings are particularly suitable for use on shafts running at high speeds not only because the friction is very low but because the softness of the rubber allows the shaft to turn on its center of gyration even though this differs slightly from the geometrical center, thus reducing the dynamic load in the bearing and the vibration in the machine.