Bearings for Pumps & Compressors
Pump and compressor bearings carry a steady radial load from the impeller or rotor, plus whatever axial thrust the hydraulics produce. Two-position arrangements dominate: one locating position that takes axial load, one floating position that only carries radial load and accommodates shaft growth.
Typical duty
- Continuous duty, often with the pump running for months between stops.
- Axial thrust that rises steeply with head or compression ratio, and can reverse on start-up.
- Process fluid temperature travelling along the shaft into the bearing housing.
- Vibration from cavitation, surging or impeller imbalance, which loads the bearings cyclically.
- Washdown and moisture in food, water and chemical service.
Recommended types & suffixes
Type, reason and the suffix that follows from it
| Type | Why it suits the application | Suffix guidance |
|---|
| Deep groove ball bearings | Floating position on small and medium pumps; quiet and low drag. | 2RS or 2Z depending on moisture, C3 for hot service. |
| Angular contact ball bearings | Locating position where thrust is moderate; paired back-to-back for stiffness. | Single row 7200/7300 series in DB or DF pairs, adjusted for preload. |
| Cylindrical roller bearings | Heavy radial load on large pumps, with NU type free to move axially. | NU for the floating position, NJ or NUP where some axial location is needed. |
| Tapered roller bearings | Combined radial and axial load on smaller vertical or gear-driven pumps. | Matched pairs, set to the manufacturer's axial clearance or preload. |
Models for this application
From the live catalogue, 15–150 mm bore
Models are listed for reference. For a specific duty we confirm the clearance, seal and lubricant before quoting -
send the application.
Installation & maintenance notes
- Determine which position locates and which floats before ordering - the floating bearing must be free to slide axially.
- Allow for thermal growth of the shaft: on hot pumps the housing fit must not clamp the floating outer ring.
- Keep the locating pair correctly adjusted; too much preload raises temperature and shortens grease life.
- Select the seal or shield for the actual environment, not the default: moisture in the housing ruins grease.
- Monitor axial vibration - rising thrust often points to wear rings, not the bearing.
Common mistakes in this industry
- Fitting a locating bearing in both positions, so thermal growth preloads the pair and the bearings overheat.
- Choosing a contact-sealed bearing for a flooded or high-speed position and losing it to friction heating.
- Ignoring the axial thrust of a vertical pump and using a radial-only bearing in the thrust position.
Further reading
Frequently asked questions
Why do pump bearings fail in pairs?
Because the arrangement is usually a locating plus a floating position, and a fault in one - wrong clearance, excessive preload, poor housing fit - changes the load the other one sees. Always replace both positions together and re-set the axial adjustment.
How is a floating bearing identified?
The outer ring has no axial restraint, so it can slide in the housing as the shaft expands. NU type cylindrical roller bearings and most ball bearings in a loose housing bore act as floating positions.
Can I upgrade a pump bearing for longer life?
Often yes: an insulated or hybrid bearing removes electrical damage on inverter-driven pumps, a higher-grade grease raises the temperature ceiling, and an optimised cage helps at high speed. The limiting factor is usually the fit and lubrication, not the bearing itself.
Sourcing for Pumps?
Send the model number, quantity and destination - we reply within 30 minutes on working days.