Some Aspects of the Performance of High-Speed Lightly Loaded Cylindrical Roller Bearings

Abstract

The paper deals with the wear problems which are sometimes experienced when operating parallel cylindrical roller bearings at high speed, with jet lubrication, in turbine mainshaft bearing practice.Tests show that considerable cage slip often takes place, as reported by previous investigators, the cage and roller assembly travelling at speeds lower than that predicted from the epicyclic relationship. I t is concluded that hydrodynamic lubrication normally occurs between the rollers and races when appreciable cage slip takes place. If the radial load on the bearing suddenly increases under these conditions, the hydrodynamic film is not always able entirely to prevent metallic contact and wear of the rollers and races.Further experimental work is required before complete understanding of the problem can be obtained. Tentative recommendations, however, are made for minimizing the incidence of this type of wear in practice. N O T A T I O NDiametral clearance between rollers and races, in. Roller diameter, in. Diameter of inner track, in. Diameter of outer track, in.Mean or pitch diameter of rollers = u, in.Eccentricity, inner to outer race centre distance, in.Minimum f i l m thickness at inner contact, in.Minimum film thickness at outer contact, in. Roller rev/min relative to the cage (measured). Rev/min of cage (measured). Rev/min of inner race. Roller to inner track diameter ratio = d/Di. D . + D 2 WIDiTangential velocity of inner race = -, in./sec. 2Eccentricity ratio = e[c. Angular velocity of cage or separator, rad/sec. Angular velocity of inner track, rad/sec. Angular velocity of roller about its own axis, rad/sec. Percentage cage slip = ( x 100, per cent.

An Advanced Apparatus for the Study of Roller and Cage Slip in High-Speed Roller Bearings

“…Unfortunately, this analysis indicated that cage and roller slip was independent of the operating conditions and that the latter (roller slip) was also independent of the roller position in the bearing. This is contrary to actual measurements [1,[8][9][10].…”

“…Not surprisingly, the measurement of roller speed, more than any other variable, has tended to limit the potential of experimental studies to date. The electromagnetic techniques generally employed for this measurement [1,[7][8][9][10] have only been capable of measuring the average speed of a single, modified roller, taken over a number of revolutions, due mainly to the inherent resolution limitations of the method. Typically, Boness [1] spark eroded a slot in the end face of one roller and mounted a small magnetic probe on the cage opposite the roller, the signal from this transducer being transmitted to a stationary receiver by a magnetic coupling.…”

“…Further, the running accuracy and dynamic stability of the test bearing may be monitored with the aid of temperaturecompensated, proximity transducers which are used in a similar manner to that employed for the study of shaft loci [8,9]. Analysis predicts that even a perfect-geometry bearing will exhibit such loci, no matter how small, with the most important single factor governing them being the bearing operating clearance [14,15].…”

Investigation of skidding in angular contact ball bearings under high speed

“…Smith [20] reported the effect of oil viscosity, diametral clearance and outer race temperature on cage slip. Poplawski [21] analyzed the effects of oil temperature on cage slip.…”

The Effects of Elastohydrodynamic Traction Behavior on Cage Slip in Roller Bearings

“…The disadvantage is that wear sometimes occurs [12]. For wear to occur there must be both sliding and a breakdown in lubrication.…”