Investigation on cage and roller slip of cylindrical solid and hollow roller bearings

Abstract

Cylindrical roller bearings are used in many industrial machines newlineand automobiles because of their higher load carrying capacity at high speed newlineconditions. In most roller bearing applications, operating conditions are such newlineas to ensure that the cage and roller motion are essentially epicyclical. newlineHowever, in some situations of high speeds and light loads, several newlineinvestigators have reported roller bearing cage slip, in which the cage and newlineroller assembly travel at speeds lower than that predicted from epicyclical newlineconsiderations. In many modern roller bearing applications such as the main newlineshaft bearings in aircraft gas turbine, inner raceway speed is high and bearing newlineradial load may be very light, the latter being caused only by rotor weight. In newlinegeneral, for a given radial clearance and light or moderate load, increasing the newlineshaft speed or the viscosity of the oil, increases the oil film thickness between newlinethe inner ring and the roller, causing a tangential driving force which is newlineinversely proportional to the film thickness and tends to decrease it. The newlineradial outward movement of the roller due to this increase in film thickness newlineand centrifugal loading of roller results in a larger frictional drag force newlinebetween the roller and outer race. To reestablish equilibrium between the drag newlineand driving tangential forces, the cage must travel more slowly than that of its newlineepicyclical value, resulting in cage and roller slip. In certain instances this cage and roller slip can be tolerated, but newlinefurther deterioration in the operating conditions can cause excessive wear of newlinethe inner race track and rollers, and lead ultimately to the early failure of the newlinebearing. Damage due to skidding will be an important factor in the bearing design requirement for future bearings to meet higher DN values.