The rational use and maintenance of scraper tires.

1. Correct selection

Each type of scraper specifies the specifications, types, grades, patterns of the tires it uses and whether there are inner tubes or not. When choosing tires, it is necessary to take into account the specific conditions of the working environment and comprehensively consider various influencing factors such as road conditions, climate, load, speed, as well as working conditions, to select tires with certain outstanding performance. If it is used for long-distance transportation, it is required to have good heat resistance; if it is used in water-rich areas, it is required to have good water resistance, etc. At the same time, certain characteristics of tires are mutually restrictive and must be comprehensively considered. One should not neglect one aspect for another.

When choosing tires, factors such as their walking quality, traction, off-road capability and the service life of the outer tread should also be taken into consideration. The tires made of inclined cord fabric have very thick side walls. They have good puncture resistance and lateral stability and are usually used under conditions of high impact loads and strong corrosiveness. However, these tires heat up quickly and are not suitable for long-distance high-speed operation. Radial tires generate less heat. When operating at high speed or over long distances, the temperature rise of the tires is relatively low. Moreover, they have good elasticity and low rolling resistance. This type of tire should be selected when the scraper is working in milky soil.

The characteristics of scraper tires, such as high load capacity, large traction force, and harsh operating conditions, require a large ground contact area of the tires to ensure a low ground contact pressure, wear resistance and puncture resistance of the tread, and low heat generation in all parts. The cross-sectional width of the tire, the high curvature of the driving surface, the position of the horizontal axis of the cross-section, the shoulder arc, the tread degree and the Angle of the crown cord all have an impact on these performances, and thus affect the service life of the tire. The cross-sectional width of a tire determines its contact area with the ground and the pressure at the contact point, which has a significant impact on the tire's wear resistance and driving stability. If the cross-sectional width is narrow, the contact area is small, the pressure at the contact point is high, the tread is prone to wear, and the service life of the tire is shortened. The curvature of the driving surface affects the width of the tire in contact with the ground and the unit pressure distribution at each point on the contact surface when it rolls under inflation and load. If the curvature is too large, the width of the tire in contact with the ground is small, the stress at the contact point is uneven, and the tread is prone to wear. If the curvature is too low, it will cause the tire shoulder to be too thick, which will lead to excessive heat generation and poor heat dissipation of the tire, causing the tire to come off the shoulder and suffer premature damage, thus shortening the service life of the tire. The horizontal axis position of the cross-section is the part where the tire degenerates and flees the most. If the H1/H2 value is too large, it will cause excessive heat generation at the tire shoulder and lead to premature tire damage. The shoulder area of the tire is the thickest part of the tire. If the curvature of the shoulder is small and the shoulder is thick, it will generate a lot of heat and have difficulty dissipating it, which can easily cause bubbling on the shoulder. The shoulder is also prone to damage from the driving environment, leading to premature tire failure. The thickness of the tread compound has a dual impact on the tire. A thick tread compound, on the one hand, can enhance the tire's wear resistance and puncture resistance, and on the other hand, it also increases the difficulty of heat generation and dissipation of the tread. The cord Angle of the tire crown is an important indicator for controlling the deformation capacity of the tire body and the load-bearing capacity of the tire after inflation. If the Angle design is improper, the tire body is prone to deformation, the load-bearing capacity will decrease, and the service life of the tire will be shortened.

The same scraper should be equipped with the same type of tires, especially the tires used on the same axle must be of the same specification, type and grade. Since the numbers of tire specifications are different from the actual size, tires with the same nominal size may have different actual sizes, which can lead to different rolling radii. When the rolling radii of tires on the same drive axle are not equal, the tire with a smaller rolling radius rotates faster than the one with a larger rolling radius, thus causing the drive axle to bear concentrated stress caused by tire sliding. For a four-wheel drive scraper, the stress caused by the different rolling radii of the tires will also be amplified through the transmission chain.

The specifications of the tires and the wheel rims must match. If the width of the wheel rims is too small, the curvature of the tire tread will be large, which will accelerate the wear of the tires. If the width of the wheel rims is too large, the two shoulders of the tire tread will touch the ground and the center will be concave, which will cause severe and uneven wear. Therefore, each type of tire specifies the permitted rims for use. In light of the actual situation of our mine's mining site, we have selected ultra-thick smooth radial tires, which have a smooth and flat tread and a large width. Therefore, the grounding area is increased, and the grounding pressure distribution is uniform, with good cutting and wear resistance. Alleviating the short service life of tires used in mining equipment is a very prominent issue.

2. Appropriate inflation pressure

Inflation pressure has a significant impact on the lifespan of tires. Both excessively high and low inflation pressure can cause tires to wear out prematurely. Maintaining normal tire pressure can reduce tire wear.

If the tire pressure is too high, regardless of whether it is overloaded or not, it will cause significant stress on the cord, reducing its ability to resist bursting when impacted. A decrease in the tire's contact area with the ground can accelerate the wear of the tread, which is not conducive to tire maintenance. When the rigidity of the outer tire and its side wall increases, it is more likely to be punctured, cut and burst, and its off-road capability and towing ability also decrease, making it easy for the tire to skid.

When the tire pressure is insufficient, the tire deforms significantly, increasing internal stress and raising temperature. This accelerates the aging of the rubber and the fatigue of the cord, eventually leading to the cord being pulled apart, the cord fabric delaminating, and the tread cracking. It also causes different rolling radii for tires of the same specification, resulting in premature tire damage. When the tire pressure is only normal, the lifespan of the tire will decrease. When the tire pressure is only normal, the lifespan of the tire will decrease. When the machine is running on an uneven road surface, if the inflation pressure is slightly lower than the normal pressure, it can actually increase the service life of the tires because it can mitigate the impact load and improve the condition of stress concentration.

3. Prevent overspeeding and overloading

Each type of scraper is specified with a maximum traveling speed and an average vehicle speed. When the machine is running at an excessive speed, the temperature of the tires rises and the fabric layers separate, which will accelerate the wear and rupture of the tires and shorten their lifespan. The attached figure shows the relationship between vehicle speed and tire lifespan. When a scraper is in motion, the dynamic load on its tires is considerable. Even when traveling at a medium speed on a flat road, the dynamic load is twice as large as the static load. The dynamic load increases with the unevenness of the road surface, the traveling speed of the machine and the rigidity of the tires. When driving on a flat road, the dynamic load is almost proportional to the square of the vehicle speed. Therefore, the load of the scraper must be less than its maximum rated load, as the tires will twist and heat up when overloaded. Excessively high temperatures can cause the fabric layer to separate and the tire to deform extremely, which can lead to rapid wear and cracking of the tire.

4. Drive correctly

Even when driving on a flat road, if the driver operates improperly, the tires can be damaged or even scrapped.

The scraper should start in a low gear. When turning, the speed should be reduced. Excessive braking should be avoided (the heat generated by emergency braking can make the rubber on the tire surface soften due to heat, and one emergency braking can wear off 0.9mm of the tire surface). When the machine is moving, it should go around the oily road surface. The greater the slope of the road surface, the greater the impact on the lifespan of the tires. Therefore, when a scraper is traveling, it should try to avoid going on slopes as much as possible.

In addition, training for drivers should be strengthened, covering aspects such as driving methods, safety techniques and technical maintenance.

5. Maintenance and care of tires

Pneumatic tires should not be placed near areas with excessively high temperatures, and welding operations must not be carried out on them. Due to the different assembly positions and loads each tire bears on the machine, the wear of each tire is also different. Therefore, regular rotation is necessary to maintain the good performance of the braking system and prevent the wheels from seizing to avoid rapid tire wear. When installing tires, they should be tightened as specified Torque tightens the nut on the tire.

6. Ensure that the road conditions are good

The condition of the road is also a factor affecting the lifespan of tires. Therefore, before operation, effective maintenance of the road should be carried out to avoid the scattering of materials on sharp turns or slopes. Obstacles on the road surface should be removed in time and the road should be kept unobstructed. If the road is damaged due to long-term use, overloading or poor surface quality, the road surface will become uneven, increasing the impact force on the tires and the probability of tire failure due to impact, shearing and cutting. To prevent the machine from overturning during sharp turns, a lateral slope should be formed on the road surface, and steep uphill sections should be excluded. As long as the above aspects are well managed, the service life of tires can be effectively prolonged and economic benefits can be improved.

The usage conditions of scraper tires are harsh, the performance requirements are high, the manufacturing process is complex, the price is expensive, and there are many factors affecting the service life. Only by accurately and comprehensively analyzing the factors that affect the service life of tires and using and managing them correctly can we fundamentally increase their service life.