How to determine if the tracks of an excavator need to be adjusted?
1. Observe the sag of the track
Normal sag range: When the excavator is stationary, the sag of the track should generally be between 30 and 50mm (specific values may vary depending on the excavator model and manufacturer's recommendations). For example, the suitable range of track sag for the Komatsu PC200 excavator is approximately 35-45mm. The sag can be determined by measuring the distance between the bottom of the track and the sprocket wheel using tools such as a steel tape measure.
The situation of excessive sagging: If the sagging of the track significantly exceeds the normal range, such as a sagging of over 80mm, it indicates that the track is too loose. This can cause the tracks to easily derail during operation, especially when the excavator is turning, crossing obstacles, or working on rough terrain, the risk of derailment will greatly increase. Moreover, overly loose tracks can cause the excavator to bounce and shake while walking, affecting the smoothness and efficiency of the operation.
The situation where the sag is too small: When the sag of the track is less than the normal range, such as less than 30mm, the track will be too tight. Tight tracks can increase the friction between the tracks and the drive wheels, guide wheels, and idler wheels, leading to increased wear of these components. At the same time, it will increase the load on the engine, reduce fuel economy, and there may be abnormal noise during walking.
2. Check the fit between the track and each component
Mesh with drive and guide wheels: Observe the mesh between the track and the drive and guide wheels. Under normal circumstances, the teeth of the track should mesh tightly and evenly with the teeth of the drive wheel and guide wheel. If there is excessive clearance between the track teeth and the teeth of the drive or guide wheels, some teeth cannot mesh properly, or the track is offset on the wheels, it may be caused by loose tracks or other problems, and the track needs to be adjusted.
Contact with the sprocket: Check if the contact between the track and the sprocket is good. The function of the sprocket is to support the upper part of the track, keeping it in the appropriate shape and position. If there is separation, uneven contact, or excessive or insufficient pressure from the track to the sprocket, it may also indicate that the tension of the track is inappropriate and needs to be adjusted.
3. Pay attention to the state of the excavator during the walking process
Walking stability: Pay attention to the stability of the excavator when walking. If there is obvious shaking, swaying or deviation when the excavator is walking, in addition to checking whether the track shoes are damaged and whether the ground is flat, improper tension of the tracks may also be one of the reasons. For example, a loose track may cause the excavator to sway on one side of the track while walking, resulting in the excavator running off track.
Abnormal noise: Listen for any abnormal noise during the excavator's movement. If there is a "click click" sound, "creak" sound, or other irregular friction sound, it may be caused by the track being too tight and the friction between it and other components increasing, or by the track being too loose and colliding with the body components during operation. These situations indicate the need to check and adjust the tension of the tracks.
How to determine if the tracks of an excavator need to be replaced?
Observe the appearance of wear and tear
Surface wear of track shoes: Check the surface of the track shoes in contact with the ground. If there are severe wear marks, such as wear depth exceeding a certain limit (generally, metal track shoes wear to 1/3/2 of their original thickness, and rubber track shoes wear to about 2/3 of their original thickness), replacement should be considered. For example, when the pattern of the metal track plate is almost worn flat, its grip will significantly decrease, affecting the walking and operational stability of the excavator.
Edge wear and deformation: Pay attention to the wear of the edge of the track shoes. Frequent turning, collisions, and other operations may cause severe edge wear, resulting in jagged or curled edges. In addition, if the track shoes deform, such as bending, twisting, etc., it will affect the normal operation of the track and cause problems such as shaking and deviation when the excavator is walking. At this time, the track shoes should also be replaced.
Check the connecting components of the track shoes
Damaged connecting bolts or pins: Check the connecting bolts, pins, and other components between the track shoes. If loose or broken bolts are found, or if the pins are severely worn or deformed, it may cause the connection between the track shoes to be unstable. In this case, even if the track shoes themselves have light wear, it may be necessary to replace the connecting components, and if the connecting components are damaged and cause other damages to the track shoes, such as cracks caused by adjacent track shoes colliding with each other, then the track shoes also need to be replaced.
Wear of connection hole: The connection hole is a critical part of the track shoe connection, and may experience increased wear after long-term use. When the connecting holes are severely worn, causing the connecting components to not fit tightly, resulting in loose connections or excessive gaps between the track shoes, the track shoes need to be replaced.
Pay attention to the working status of the track shoes
Abnormal walking: During the excavator's walking process, if abnormal noises such as "clicking" or "creaking" are heard, it may be due to abnormal friction between the track shoes and other components, or damage such as cracks in the track shoes themselves. At the same time, if you feel obvious shaking, swaying, or instability when the excavator is walking, in addition to checking the tension of the tracks and other factors, you should also consider whether the track shoes are damaged.
Easy derailment: If the excavator frequently experiences track derailment under normal working conditions, it may be caused by wear, deformation, or uneven tension of the track shoes. After excluding other factors, such as the normal operation of the track tensioning device, guide wheels, and drive wheels, it is necessary to carefully check whether the track shoes need to be replaced.
Consider work environment and usage time
Inspection after harsh working environment: If the excavator works in harsh working environments, such as mines, quarries, and other areas with many rocks and sharp objects, or in highly corrosive environments (such as chemical sites), the wear and damage of the track shoes should be checked in a timely manner. Even if there are no obvious problems with the appearance, it may still need to be replaced due to damage to the internal structure.
Expiration of service life: Depending on the type, quality, and working intensity of the track shoes, the service life of metal track shoes is generally around 3000 to 4000 hours, while that of rubber track shoes is around 1500 to 2500 hours. When the track shoes approach or exceed this usage time range and show signs of wear or damage to a certain extent, replacement should be considered.
Excavator tracks from different brands are usually not replaceable at will, mainly for the following reasons:
Differences in size specifications
Length and width: The track length and width of each brand of excavator are determined based on the body design. For example, the track width of the Komatsu PC200 excavator is about 600mm, while the track width of the Caterpillar 320 excavator is about 700mm. If the tracks with inappropriate width are replaced, it will lead to a decrease in the stability of the excavator's walking. A track that is too wide may interfere with other components of the aircraft, while a track that is too narrow may increase the ground pressure and make it easy to get stuck in soft ground.
Pitch and number of sections: The pitch of the track refers to the distance between the centers of two adjacent pin holes, and the pitch of different brands of excavator tracks varies. The number of sections also varies depending on the size and design requirements of the excavator. For example, the track pitch and number of the Hitachi ZX330 excavator are different from those of the Doosan DX300 excavator. Inappropriate pitch and number of pitches can cause the track to fail to mesh correctly with the drive wheel, guide wheel, and idler wheel, resulting in the track not functioning properly and even potentially derailing.
Different interface designs
Connection method: There are differences in the connection method of tracks between brands. Some brands use bolt connections, while others use pin connections. For example, Sany excavator tracks may use a special specification of connecting pins, while XCMG excavator tracks may be connected by bolts of different sizes. The difference in this connection method makes it difficult for different brands of tracks to be interchangeable, as mismatched connection interfaces can lead to installation difficulties, and loose connections are prone to occur during excavator operation, causing safety hazards.
Fixed interface with the body: The fixed interface between the track and the excavator body also varies depending on the brand. Each brand considers the body structure and stress conditions during design, and has specific requirements for the position, shape, and size of fixed interfaces. If mismatched tracks are installed on the excavator, they may not be securely fixed to the body, affecting the normal movement of the excavator and even causing the tracks to fall off during operation.
Material and performance differences
Material quality: The material quality and composition of excavator tracks from different brands vary. Some high-end brands may use high-quality materials such as high-strength alloy steel or specially formulated rubber, which have better properties such as strength, wear resistance, and corrosion resistance. For example, Caterpillar's metal tracks use alloy steel with high hardness and toughness, while some small brand track materials may be relatively poor. If replaced randomly, it may shorten the service life of the track and increase maintenance costs due to substandard material performance.
Performance matching: The performance of excavator tracks is matched with the working parameters and design characteristics of the excavator. For example, some brands of excavators are designed for heavy-duty excavation work, and their tracks have strong load-bearing capacity and impact resistance; However, some excavator tracks used for light municipal operations focus more on the smoothness and low noise of walking. If unsuitable tracks are replaced, it may affect the efficiency and performance of the excavator, such as problems with walking speed, traction, climbing ability, etc.
