According to the survey, there is a common tire wear phenomenon in the production of semi-trailers. Generally running 2x104 km appears more obvious, driving 5x104 km is the most significant, wear tires account for about 30% of the total number of semi-trailers. On the basis of investigation and analysis, some measures to improve the abnormal wear of semi-trailer tire are put forward.

Causes of abnormal wear of semitrailer tires

The life of the tire is related to the structural type of the semi trailer, the condition of use, the technical condition of the vehicle, the technical level of the driver, the maintenance of the tire and the timely repair of the tire.

1. The regulation of the deviation of the tire pressure

Air inflation is one of the main reasons for abnormal wear of tyres. Many tyres are scrapped for this reason.

When the tire's air pressure is lower than the standard, it can increase the contact area with the ground and reduce the average pressure of the tire on the road surface. However, as the tires bend to the inside, the "bridge effect" is produced, and the load in the middle of the tread is smaller, while the load on the tread edge increases sharply, making the stress of the tire material increasing. The uneven distribution of the pressure on the contact area will lead to uneven wear of the tread, and the edge of the driving surface is seriously worn, and its wear usually forms a toothed or wavy shape.

2. The tire pressure is too high

When the tire is working under high pressure, the deformation of the tire and the small contact area of the tire and the pavement are small. Therefore, the pressure on the ground area increases and the wear of the middle part of the tread is accelerated.

3. Overloading of tires

When the semitrailer is overloaded or the load is not distributed correctly on the cargo box, the wear characteristics of the overloaded tire are similar to that of the tire when the tire is running at a low pressure. But the wear is more serious when overloading, because in this case, the pressure distribution on the contact area of the tire and the pavement is uneven, and the stress of the cord of the fetal body increases, which aggravates the rapid increase of the temperature of the running surface of the outer tire. In this case, the fatigue and strength of tire materials are reduced faster than those with low pressure under the same deformation.

4. The wheel plane is not perpendicular to the road surface

When the semi trailer is loaded, the axle housing and the half axle casing (or axle head) can be deformed because of the load, and the wheel incline may appear. At the same time, the wheel incline can also be aggravated because of the assembly gap between the hub and bearing, or the driving in the area with large arch. The wheel and the pavement are not vertical, which will cause the uneven distribution of the pressure distribution on the ground area of the tire, and the tire is in the slippery state of the side rolling edge, causing the tire wear. In this case, the inner side of the inner tire of the trailer axle is seriously worn out.

5, the structure parameter matching of semi trailer is not reasonable

The force acting on the tire depends on factors such as load, road condition, driving speed and vehicle parameters. When the vehicle runs on the uneven pavement, the tire will be subjected to greater dynamic load, and its value increases with the increase of load, road roughness, driving speed, suspension and wheel stiffness. Under the same conditions, if the semi-trailer's structural parameters are reasonably designed to give it a good damping property, the tyre will be protected from excessive impact load. However, at present, most of the medium-sized semi trailer produced by the domestic manufacturers, the suspension part of the suspension is basically the rear suspension assembly of the medium truck, and the same is the use of the adding of the measures to increase the strength of the spring. We think this combination is not very good to ensure the reasonable matching of the rigidity of the semi-trailer frame, suspension and tire, so that the semi-trailer does not have good vibration damping characteristics. It is one of the important factors to make the tire dynamic load and accelerate the tire wear.

Whether the brake allocation is reasonable is related to vehicle structural parameters and conditions of use. The axle load of the trailer is very different because of the empty and full load of the semi trailer, and the weight of the trailer is high and the load transfer is large when the brake is braking. However, at present, the medium semi trailer produced in China is basically not equipped with the power regulation device. Therefore, it is difficult to ensure the ideal characteristics of the empty and full load condition of the vehicle braking force at the same time. Requirements can only be designed according to the requirements of full load characteristics. In this way, when the semi-trailer is not fully loaded, there will be excessive braking of the axle wheel. During the braking, the tire of the trailer axle often appears to be "locked" and slippage will accelerate the wear of its tread.

6, the poor technical condition of semitrailer

The service life of tires is closely related to the technical conditions of semi trailers. In the user survey, we know that many bad factors of the technical condition can lead to early damage or rapid wear of tyres.

Bad performance of brake lag or hub bearing

In this case, the tyre has great resistance to running, and at the same time, the heat generated by the brake hub and tyre will increase rapidly, which will cause the tire tread to wear rapidly.

The difference between the center of the traction pin and the axle center of the trailer axle is very large.

In this case, the tire is affected by an additional lateral force, which increases the probability of the left and right swing of the semitrailer and causes the wear of the tire tread.

Misplacement of plate springs

The dislocation between the plates in the plate spring assembly is serious, which will cause a great change in the stiffness and damping of the plate spring assembly, which causes the bad vibration and impact of the semitrailer in the driving, and causes the running performance of the tire to be bad, which leads to the abnormal wear of the tire.

Mass imbalance of wheel rotation

The wheels of high-speed wheels produce vibration with balanced differential wheels, causing shocks in their rotating planes. The impact load is applied to the tire, causing additional stress in the carcass, resulting in uneven uneven wear of the tread.

7, the damage of rubber damping sleeve on the bearing shaft of the traction seat

The single degree of freedom traction seat is widely used in the medium semi-trailer currently produced in China. Because only the longitudinal oscillating traction seat can not meet the requirements of the existing road conditions well, the manufacturer basically adds a rubber damping sleeve to the supporting shaft of the single degree of freedom traction seat to make the traction seat get a moderate lateral swing angle, so as to reduce the impact and tire wear of the semi trailer. However, when the plastic deformation of the rubber sleeve is large or damaged, it will not only cause the poor swinging performance of the traction seat, but also cause the tilting of the traction seat surface in the horizontal plane, which makes the semi trailer tilting, resulting in the uneven force of the trailer axle tire and the acceleration of the tire wear.