Bearings are assemblies which are used to fix axles and shafts in place while allowing them to rotate. They receive and transfer the load to other moving elements of the structure. They are used in many automotive parts: from wheels to alternators.

Design of bearings

In modern cars, you may come across rolling and plain bearings. The former are used in wheel hubs, shock absorbers, compressors, pumps, and other moving assemblies. The latter are more common in engines, starters, and turbochargers.

All components regardless of their operating principle differ by the type of loads they are exposed to, which affects their design. For example, radial roller bearings consist of outer and inner races which are used to join different vehicle assemblies together. The inner surfaces of the rings are fitted with grooves along which rolling bodies (balls or rollers) move. In most cases, there is a separator with holes for the rolling elements between the rings. Thrust bearings have a similar design but instead of races, they have upper and lower rings between which the balls and rollers move.

Plain bearings don’t have any rolling elements. They consist of a housing, often separable, with a bushing made of anti-friction material. They have oil inlets and oil supply passages. The shaft inserted into the bushing doesn’t come into contact with it as the gap between them is filled with oil.

Maintenance tips

• Replace covers, seals, and o-rings on time. These components are very sensitive to contamination and lack of lubricant.
• Use special tools (drivers and extractors) to mount and dismantle the parts. Otherwise, you risk damaging assembly components or their mounting seats.
• In most cases these components are disposable. They should not be reinstalled.
• Do not overload your car. This will expose many suspension components to high loads.
• In the belt drive systems, make sure that belts are properly tensioned and pulleys are correctly aligned.
• Shift to neutral when you are stuck in a traffic jam or stopped at a traffic light. That will help you extend the service life of bearing assemblies used in the clutch system.
• Change oil in the engine on time. Components which ensure the rotation of the crankshaft and camshaft have the same lubrication system. If their channels get clogged, these assemblies will fail prematurely.

Malfunction symptoms

Deterioration of the separators, cracks, or fatigue wear of the raceways are indicated by crunching and humming noises that arise when the assembly is in use. In some cases, the mechanism starts jamming. Sometimes the parts overheat. Oily stains around the assembly are the sign of damaged seals and O-rings. If wheel hub bearings have deteriorated or get stuck, the vehicle can deviate from its path. Uneven tyre wear can be also observed.

Malfunction causes

The use of inappropriate lubricants, as well as an excessive or insufficient amount can cause the parts to fail. Excessive vibrations, for instance of a camshaft, lead to dislodgement from the bushing which is dangerous for the latter. High loads also cause wear and tear of the components.

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