Centrifugal Pumps Design and Application 2nd ed - Val S. Lobanoff, Robert R. Ross (Butterworth-Heinemann, 1992)

Rolling Element Bearings and Lubrications 549
Figure 20-15. Angular contact bearings commonly used for thrust take-up in
centrifugal pumps.
a) Skew of ball separator promotes lubricant flow from side "a" to side "b,"
b) Back-to-back mounted angular contact bearings.
c) Face-to-face mounted angular contact bearings.
Figure 20-16. Advantageous lubrication arrangement ensures optimized delivery
of lube oil to all bearings (courtesy of KSB Pump Company, Kaiserslautern
Germany).
Magnetic Shaft Seals in the Lubrication Environment
Most pump shaft seals are generally inadequate, ANSI pumps are usually
furnished with elastomeric lip seals. When these seals are in good
condition, they contact the shaft and contribute to friction drag and temperature
rise in the bearing area. After 2,(XX) to 3,000 operating hours,
they are generally worn to the point at which they no longer present an
effective barrier against contaminant intrusion. Percent failure vs. hours
to leakage for two types of lip seals is shown in Figure 20-17 [10].