In hot summer weather, incidents of vehicle tire explosions or spontaneous combustion often occur, posing a great danger to driving safety belts. Hot wheel ends are a common cause of tire explosions or spontaneous combustion, so car owners are paying more attention to this.

In general, during the driving process of a truck, heat accumulation occurs at the wheel end, especially when the vehicle is fully loaded. The temperature at the wheel end will increase, as long as it does not exceed 60 ℃, which is a normal phenomenon. If the temperature is exceeded and the frequency of overheating is relatively high, or if a single wheel end always experiences overheating, it can be judged as abnormal heating. There are two main factors that cause this situation: one is the bearing, and the other is the brake drum.

1. High temperature of bearings

The bearing is installed on the inner side of the wheel end, at the axle head of the axle, mainly used to bear the axle and tires. It not only assists in bearing the weight of the vehicle, but also bears the left and right stresses of the axle when turning. The occurrence of high temperature in bearings is mainly due to tight assembly or poor lubrication. After the bearing experiences high temperature, the internal lubricating grease will melt out, causing damage to the bearing and also affecting the braking effect.

One factor that causes high temperatures in bearings is lubricating grease, commonly known as butter. If the butter used is not up to standard, during long-distance and long-term driving conditions, the internal and external bearings will experience an increase in heat due to increased friction between metals, resulting in an abnormal increase in bearing temperature and ultimately causing bearing damage.

If the quality of the lubricating grease is not a problem, it is necessary to check whether there is any problem of improper assembly and adjustment, such as excessive tightening of screws, which can cause high temperature phenomenon at the wheel end during operation, leading to butter evaporation. This can be checked using a temperature measuring gun to check the temperature of each wheel hub. If there is an ultra-high temperature phenomenon at a single wheel end, it is likely that the adjustment is too tight.

It is worth noting that when adding butter to the bearings, do not be too greedy, just use an appropriate amount. Excessive butter not only has the opposite effect on the lubrication effect, but also may block the ABS sensor probe.

Since we are discussing this topic, by the way, let me share the maintenance steps for wheel hub bearings:

(1) Stop the vehicle steadily, set up the vehicle bridge, and ensure the safety of the operation;

(2) Remove the decorative cover and dust cover of the wheel hub and axle head;

(3) Remove the tire nut and tire, taking care not to damage the bolt threads;

(4) Remove the wheel hub with a special tool;

(5) Scrape off the old lubricating grease from the bearings, journals, and hub cavities, clean the hub bearings and journals with a cleaning agent, dry them with a clean cloth, and finally clean the hub cavities;

(6) Check the wheel hub bearing and bearing race, and find cracks, fatigue peeling, loose bearing rollers, and pitting on the bearing race. Replace the bearing;

(7) Check the fit between the inner diameter of the bearing and the journal, and the fit clearance should be ≤ 0.10mm. When measuring the journal, measurements should be made on the upper and lower parts of the vertical ground. If the fit clearance exceeds the specified usage limit, the bearing should be replaced;

(8) After confirming that all components meet the requirements, apply lubricating grease to the inner bearing and place it in the hub;

(9) When applying lubricating grease to the bearing cavity, do not apply too much. Squeeze the lubricating grease into the bearing until it emerges from the other side of the bearing;

(10) Install the wheel hub and outer bearing back, install the shaft nut, tighten it with a shaft wrench according to the specified torque, and rotate the wheel hub a few times to check the installation of the bearing, so that it can rotate freely without feeling axial clearance;

(11) Install lock plates, fixing nuts, tires, dust covers, and decorative covers in sequence. Do not tighten or loosen the screws too tightly. Tightening them too tightly can cause the bearing running clearance to be too small, causing bearing erosion. If it is too loose, it can cause sliding between the bearing and the wheel hub or axle, causing wheel shimmy and unstable driving. In severe cases, the wheel may fly out.

2. Brake drum overheating

The brake drum is the area with the highest heat generation at the entire wheel end, as it needs to generate friction with the brake pads to provide braking force. Friction generates heat, so the brake drum basically generates heat. Its temperature is related to the environment, vehicle speed, road conditions, braking frequency, load capacity, and other information. Generally, it is between 100 and 200 ℃, and in some cases, it can even reach over 300 ℃.

In fact, when the temperature of the brake drum exceeds 200 ℃, it is easy to burn the tire nozzle and cause the vehicle to burst. When the vehicle's brakes do not return or the friction components show abnormal wear, it is more likely to cause the brake drum to overheat.

The owner can lift the vehicle and rotate the wheels to see if they are flexible. If there is friction, it indicates that there is interference inside the brake drum;

Rotate the tire and press the brake pedal to check if the brake returns quickly and thoroughly. If it does not return or returns slowly, it indicates a malfunction in the brake system and the vehicle needs to be sent for repair as soon as possible.

It is recommended that car owners choose products that are suitable for the operating conditions when purchasing trailer axles, paying attention to the inspection of quality and performance, especially key components such as bearings, wheels, and brake components. They should try to choose high-strength, high toughness, and high heat capacity products customized for freight vehicles, which can also ensure reliable and stable performance output in high-speed and heavy-duty usage environments.