In brief
Rolling bearings are bearings in which balls or rollers roll between inner and outer rings, guiding and supporting shafts with low friction.
Contents
What is Rolling bearing?
A rolling bearing usually consists of an inner ring, an outer ring, rolling elements and a cage that keeps the rolling elements apart. Unlike a plain bearing, motion is produced by rolling instead of sliding, which reduces friction and starting torque. According to the shape of the rolling elements, a distinction is made between ball bearings and roller bearings, the latter including cylindrical roller, tapered roller, spherical roller and needle roller bearings. According to the direction of load, there are radial and thrust bearings.
The designation of rolling bearings is largely standardised internationally, for example in accordance with DIN 623-1. A basic designation describes the type and dimensions, while prefixes and suffixes identify versions such as sealing, internal clearance, cage material or accuracy. The basic rating life is calculated in accordance with ISO 281.
Common causes of failure are inadequate lubrication, contamination, mounting errors, overload and misalignment. Vibration monitoring is a widely used method for detecting bearing damage at an early stage. Suitable lubrication, clean mounting with the right tools and correct fits extend service life considerably.
In practice: maintenance and procurement
For replacement, the complete designation including suffixes is what counts. Two bearings with the same basic designation may differ in sealing or internal clearance and are then not readily interchangeable.
Synonyms and abbreviations: rolling-element bearing · anti-friction bearing · ball bearing (subtype) · roller bearing (subtype)
Frequently asked questions
What do suffixes such as 2RS, 2Z or C3 mean?
Suffixes describe design details. 2RS usually stands for contact seals made of elastomer on both sides, 2Z for sheet steel shields on both sides. C3 means a larger internal clearance than normal, as chosen for example for higher operating temperatures or tight fits. Some suffixes are manufacturer-specific, so their meaning should be checked in the relevant catalogue.
How can bearing damage be detected early?
Typical signs are changed running noise, increasing vibration, higher bearing temperature and discoloured or contaminated lubricant. Vibration analysis can often detect damage to raceways or rolling elements weeks before failure. Temperature measurement and ultrasonic methods are also used. It is important to compare measured values over time rather than looking only at individual readings.
Are rolling bearings from different manufacturers interchangeable?
For standardised designs, the boundary dimensions are defined internationally, so bearings with the same basic designation are generally dimensionally interchangeable. Differences can exist in load ratings, cage design, sealing, internal clearance and grease fill, and some suffixes are used differently by different manufacturers. The data sheets of both bearings should therefore be compared before switching.