September 16, 2025
The quality of bearing installation directly affects its service life and the stability of equipment operation. Many mechanical failures result from improper installation. The following 6 practical tips will help you avoid common mistakes and efficiently complete bearing assembly:
Wipe the bearing inner ring, outer ring, rolling elements, and mounting surfaces (journal, bearing housing bore) with anhydrous ethanol or acetone to remove oil stains, iron filings, dust, and other impurities—even tiny impurities can accelerate bearing wear, causing abnormal noise or premature failure. If the installation environment has a lot of dust, it is recommended to lay a dust-proof cloth and operate with powder-free gloves.
Use a micrometer to measure the dimensional tolerance of the journal and bearing housing bore (e.g., for the journal with inner ring interference fit, the tolerance must meet the drawing requirements), and use a roughness tester to check the surface roughness (usually requiring Ra ≤ 0.8μm). At the same time, inspect the bearing appearance to confirm there are no cracks or rust, and that the rolling elements rotate without jamming. Avoid installing damaged bearings.
Never hit the bearing ring directly with a hammer! For small-sized bearings, a copper or nylon sleeve can be used (the inner diameter of the sleeve is slightly larger than the shaft diameter, and the outer diameter is slightly smaller than the bearing outer ring). Transfer force evenly to the ring with interference fit through the sleeve (e.g., if the inner ring has an interference fit with the shaft, tap the sleeve to act on the inner ring; if the outer ring has an interference fit with the housing bore, tap the outer ring).
When installing large-sized bearings with interference fit (such as slewing ring bearings for excavators), prioritize using an induction heater to heat the inner ring (or outer ring), with the temperature controlled between 80-120℃ (monitored by an infrared thermometer). It is strictly forbidden to use open flames such as gas stoves or oxyacetylene welding for heating—open flames will cause local overheating of the bearing, damage the steel hardness, and shorten the service life.
When cold-fitting bearings with an inner diameter ≤ 50mm, use a bench press to apply pressure slowly. Ensure the direction of pressure is parallel to the bearing axis, and the force application point is concentrated on the end face of the ring with interference fit to avoid bearing deformation due to offset pressing. If there is no press, a bolt pushing method can be used to achieve even force through gaskets.
When installing bearings with rubber seals (such as double-sided rubber-sealed 2RS bearings), confirm the direction of the seal lip—for waterproof scenarios, the lip should face the outside (the side in contact with water). During installation, avoid scratching the seal lip by the shaft shoulder; a small amount of grease can be applied to the journal to assist in installation.
The bearing expands after heating and must be quickly fitted onto the journal (or installed into the bearing housing) within 1-2 minutes to avoid jamming after cooling. During installation, a small amount of high-temperature grease can be applied to the mating surface to reduce friction; after fitting, immediately fix it with a positioning nut or end cover to prevent axial movement of the bearing after cooling.
After the hot-fitted bearing cools to room temperature, it is necessary to replenish grease (especially for open bearings): evenly apply grease between the rolling elements and the cage, with the filling amount accounting for 1/3-1/2 of the bearing's internal space—excessive grease will increase resistance and cause high temperatures, while insufficient grease will lead to poor lubrication.
After installation, gently rotate the bearing outer ring (or shaft) by hand. It should feel smooth without jamming or obvious abnormal noise. If there is a "stuck feeling," it may be due to installation deviation or impurity mixing, and disassembly and inspection are required.
After installing ordinary deep groove ball bearings, the axial clearance should meet the equipment requirements (e.g., the clearance of motor bearings is approximately 0.01-0.03mm); for heavy-load scenarios such as excavator travel bearings, feeler gauges should be used to check the radial clearance to ensure no over-tightening causes overheating.
If the bearing is equipped with a dust cover or seal ring, check whether it is installed in place and free of deformation, and whether the interface is fitted—for example, if the spring ring of the skeleton oil seal falls off, it will cause lubricating oil leakage, and the spring ring needs to be reinstalled and pressed tightly.
