Reason for fracture
1. Long term overload work
Overload bearing: When excavators carry out excavation or lifting operations beyond their designed bearing capacity, the weight borne by the excavator track rollers will significantly increase. For example, when excavating hard rocks or overweight objects, the entire weight of the excavator plus excavation resistance will be transmitted to the support wheels through the chassis. If this overload situation occurs frequently, the internal structure of the supporting wheel will gradually damage due to long-term exposure to excessive pressure, ultimately leading to fracture.
Uneven stress: When the center of gravity of the excavator deviates during operation, such as excessive extension of the excavation arm or carrying heavy objects on one side, the excavator track rollers will experience uneven stress. Some of the excavator track rollers are subjected to pressure far beyond normal levels, and if left in this state for a long time, these excavator track rollers are more prone to breakage.
2. Component wear and fatigue
Normal wear accumulation: During long-term operation, the surface of the supporting wheel, bearings, and shaft components will experience wear. For example, the friction between the wheel body and the track will gradually thin the surface of the wheel body. As wear accumulates, the strength of the supporting wheel will decrease. When the wear reaches a certain level, under normal working pressure, the supporting wheel may break due to inability to withstand it.
Fatigue crack propagation: The support wheel continuously supports the weight of the excavator and rotates with the movement of the track, during which it is subjected to alternating stress. After long-term repeated action, fatigue cracks will occur inside the supporting wheel. These cracks will gradually propagate under continuous stress, and once the cracks reach the critical length, the supporting wheel will fracture.
3. Poor lubrication
Insufficient lubricating grease: If the excavator track rollers are not lubricated according to the prescribed time and amount, the friction between the internal bearings and moving parts such as shafts will increase. This will cause the components to generate more heat during operation, thereby accelerating their wear and tear. For example, when the lubricating grease is severely insufficient, there will be direct dry friction between the ball bearings and the raceway of the bearing, which will quickly damage the bearing and increase the risk of the supporting wheel breaking.
Poor quality lubricating grease or contamination: Using lubricating grease that does not meet the requirements, such as poor quality, inappropriate viscosity, or poor wear resistance, cannot provide good lubrication and protection for the excavator track rollers. In addition, if the lubricating grease is contaminated with impurities such as mud, water, or metal shavings, these impurities can exacerbate wear between components and may also cause damage to the excavator track rollers.
4. Quality issues
Material defects: During the manufacturing process of the supporting wheel, if there are quality problems with the materials used, such as air holes, inclusions, or uneven material inside, the strength of the supporting wheel will not meet the design requirements. Under normal working pressure, these defective excavator track rollers are prone to cracking and fracture.
Improper processing technology: The processing accuracy and technology of the supporting wheel also have a significant impact on its quality. If the machining dimensions of the wheel body do not meet the standards during the manufacturing process, such as diameter deviation of the shaft, insufficient roundness of the bearing seat, etc., it will cause problems in the fit between the components. During work, these unreasonable combinations can generate additional stress inside the support wheel, leading to fracture.
5. External impact and collision
Working environment factors: Excavators may be hit by rocks when operating in harsh working environments, such as on rocky construction sites or mines. These unexpected external impacts can cause damage to the wheel body or internal structure of the supporting wheel, resulting in cracks or deformation. If the impact force is strong enough, it may directly cause the supporting wheel to break.
Collision caused by improper operation: During the operation of the excavator, if the operator is not proficient or careless, such as colliding with other objects (such as buildings, large equipment, etc.) while walking, the excavator track rollers will also be severely impacted, thereby increasing the possibility of breakage.
Avoiding methods
1. Reasonable operation
Control workload
The operator should be familiar with the rated working parameters of the excavator, including maximum excavation force, lifting capacity, etc., to avoid overloading the excavator. Before excavation, it is necessary to estimate the properties and weight of the excavated material. For example, for hard rocks, the excavation depth and angle should be reasonably controlled to prevent excessive excavation resistance. During lifting operations, ensure that the weight of the lifted object is within the lifting capacity of the excavator, and avoid overloading the support wheels due to excessive use.
Maintain a stable center of gravity
When operating an excavator, always pay attention to the center of gravity position of the machine body. Avoid excessively stretching the digging arm or carrying heavy objects on one side for a long time. During the excavation process, try to make the excavation movement smooth and symmetrical. For example, when excavating ditches, excavate evenly on both sides to prevent the excavator's center of gravity from shifting to one side. When working on a slope, the position and posture of the excavator should be adjusted to make the tracks parallel to the slope direction, reduce the inclination angle of the machine body, and ensure even force distribution on the support wheels.
Avoid collision
The operator should maintain a high level of attention and operate the excavator with caution. During walking and homework, pay attention to the surrounding environment and avoid collisions with other objects. In a small workplace, it is necessary to plan the walking route in advance, control the walking speed and turning angle. For example, when approaching buildings or other equipment, sufficient safety distance should be left and careful operation should be carried out to prevent the excavator's tracks or support wheels from colliding with obstacles.
2. Regular inspection and maintenance
Wear and tear inspection
Regularly conduct comprehensive inspections of the excavator track rollers, with inspection intervals determined based on the excavator's working intensity, typically every 100 to 200 working hours. When inspecting, check whether there is wear, scratches or cracks on the surface of the supporting wheel body. For wear, tools such as calipers can be used to measure the thickness of the wheel body, compare it with the original size, and determine the degree of wear. If the wear of the wheel body exceeds the specified limit (usually specified in the excavator manual), the supporting wheel should be replaced in a timely manner.
Lubrication and maintenance
Strictly follow the requirements of the excavator manual and regularly lubricate the excavator track rollers. It is generally recommended to add lubricating grease every 50 to 100 working hours. Choose lubricating grease that is of qualified quality and suitable for the working environment of the excavator, and ensure that the grease can be fully filled between the bearings and moving parts of the excavator track rollers when adding lubricating grease. At the same time, it is necessary to check the sealing condition of the lubricating grease to prevent leakage or contamination.
Check internal components
Regularly remove the sealing cover of the heavy-duty wheel (if allowed) and inspect the condition of internal components such as bearings and shafts. Check whether the bearings are worn, whether the ball bearings are detached, and whether there is wear or cracks on the surface of the shaft. If there are signs of damage to internal components, they should be replaced in a timely manner to avoid further deterioration of the problem leading to the fracture of the supporting wheel.
3. Ensure component quality
Choose high-quality products
When purchasing support wheels, choose suppliers with reliable quality and good reputation. High quality excavator track rollers are usually made of high-quality materials, such as alloy steel that has undergone strict heat treatment, which has high strength and toughness. At the same time, it is necessary to check the manufacturing process of the supporting wheel, such as machining accuracy, surface treatment, etc. High quality excavator track rollers have high dimensional accuracy and tight and reasonable assembly of various components during the machining process, which can effectively reduce the generation of internal stress.
Check component specifications
Ensure that the specifications of the purchased support wheels meet the requirements of the excavator model. Different models of excavators have different requirements for parameters such as the size and load-bearing capacity of the excavator track rollers. If the specifications of the excavator track rollers do not match, it may lead to improper installation and uneven force distribution, thereby increasing the risk of supporting wheel fracture. Before installing the supporting wheel, carefully check the model and specifications of the components, and install them according to the correct installation method.
