Automotive Bearings: Functions & Care
When driving, you might only focus on the engine's power and the steering's ease of control, but rarely consider the hidden heroes within your car: bearings. Calling them the "joints" of a car is no exaggeration: our arms' flexible movement depends on joints, while the axles of a car's wheels and the high-speed rotation of the engine's crankshaft all rely on bearings to bridge the gap.
Their abilities are substantial: they transform high-friction "sliding" motion into low-friction "rolling" motion. This not only allows parts to rotate more smoothly, but also supports the vehicle's weight (for example, the wheels support the entire vehicle) and the lateral forces of cornering. Whether it's the engine, transmission, wheels, or steering system—wherever there's rotation, there are bearings. A bearing problem can mean the car will either stop turning or become shaky and noisy, compromising safety.
Bearings are also categorized by "job type," with different positions performing different tasks.
Bearings aren't one-size-fits-all. Just as workers in different positions in a factory have different jobs, the bearings in a car are also categorized by their specific job requirements. The most common types are rolling bearings and sliding bearings. Most family cars use rolling bearings because they rotate more smoothly and offer higher precision. If you're categorizing bearings by their mounting location, you need to know these three types:
Wheel hub bearings: These are the wheel's loyal companions, supporting the weight of the vehicle while also withstanding the pull of cornering. The wheel hub bearings in newer cars are now upgraded with built-in sensors that monitor speed and temperature in real time, alerting safety systems like ABS and ESP. For example, when you brake suddenly, they can help with anti-lock braking, ensuring greater stability.
Engine bearings: The engine's temperatures and pressures are high, so bearings must withstand both high temperatures and high pressures. For example, crankshaft bearings rotate at thousands of revolutions per minute and rely on the oil film formed by the engine oil to reduce wear. Modern cars also feature ceramic coatings on the bearings to make them more wear- and heat-resistant.
Gearbox bearings: Gearboxes shift gears and transmit power, and bearings help the gears rotate smoothly. If they fail, shifts may be jerky or even impossible to engage.
With the popularity of new energy vehicles and lightweight cars, bearings are also undergoing upgrades.
New energy vehicles are becoming increasingly popular, and as they become lighter, bearings are also evolving to keep up.
The motors in new energy vehicles rotate extremely fast, reaching 15,000-20,000 revolutions per minute, much faster than traditional engines. Ordinary bearings simply cannot withstand this speed. Therefore, manufacturers have developed "ceramic bearings"—made of silicon nitride ceramic, which is less than half the weight of steel. This reduces centrifugal force and wear, and also protects against "corrosion" caused by the electric current in the motor, making them extremely durable.
To make cars lighter and more fuel-efficient (or energy-efficient), bearings are also being "reduced in weight": using aluminum alloy for the bearing seat and carbon fiber for the retaining cage, they are over 30% lighter than traditional steel components, making the car more efficient.
"Smart bearings" are also available. They have built-in temperature and vibration sensors, acting like a "thermometer" and "vibration monitor" for the bearings. If a bearing wears or vibrates abnormally, it will send an alert to the vehicle's computer, reminding you it's time for repairs, thus preventing mid-road failures—such as a wheel suddenly seizing, which could be extremely dangerous.
Pay attention to daily car maintenance to extend the life of your bearings.
To minimize bearing problems, pay attention to the following points during driving and maintenance:
Avoid sudden acceleration and braking: This exposes the bearings to sudden and excessive forces, causing wear.
Check the wheel hub bearings regularly: Rain and driving on bad roads can easily cause mud and sand to enter the bearings, damaging the grease. Generally, wheel hub bearing grease should be changed every 80,000-100,000 kilometers.
Don't change the engine oil recklessly: Engine bearings rely on oil for lubrication. Using inferior oil can cause impurities to wear out the bearings. Adding too little oil can leave the bearings unlubricated and easily burn out.
Be alert to these signs: If you hear a buzzing sound from the wheels while driving, or if the steering becomes heavy or the car body shakes unexplained, it's likely a bearing problem. Visit a repair shop immediately to get it checked out; don't delay.
