The undercarriage of a bulldozer typically represents an average of 50% of the machine's parts and service costs. Therefore, it is crucial to select the appropriate undercarriage from the outset and to maintain it properly.

To choose the correct undercarriage, several key questions must be considered:

How long will I own this machine?

How many hours per week will I operate this machine?

What are the typical ground and soil conditions in my work area?

What impact conditions will I face?

What attachments will be used on the machine?

What are the typical grades and slopes at my job sites?

Maintenance is the best method to reduce ownership and operating costs, extend the lifespan of the undercarriage, and prevent failures. One of the primary actions to undertake is a daily inspection, checking the majority of components to ensure everything is functioning properly and exhibiting no abnormal wear.

The first items to check are the outer edges of the tracks to ensure that no bolts are missing or loose. Next, inspect the track link assembly and bushings to ensure there are no abnormal scalloping or pits on the bushings, as these may indicate wear from forward or reverse movement, or stepping.

Following this, examine the sprocket segment. Within the sprocket pocket, check for any mushrooming of the iron, which could indicate high-speed forward or reverse movement. Then, inspect the idlers for any ridging or abnormal adjustments, ensuring that everything appears to be in good condition. Afterward, verify that all track rollers are secure and that there are no obstructions preventing their operation.

Lastly, assess the carrier rollers to ensure that debris does not accumulate on top of the undercarriage, which may impede their rotation. If the carrier rollers cannot rotate, the tracks will roll over them, wearing down flat spots on the tops of the rollers, which accelerates wear and reduces the undercarriage's lifespan.

Another critical aspect to pay attention to is track tension. One should aim to observe two dips between the drive sprocket and the idlers. A string can be drawn from the top to the bottom, ensuring that there is about one inch of space between the grouser bar and the string to indicate proper tightening. Additionally, check the chrome plating for maximum stretch; exceeding the maximum stretch will result in wear on all iron components.

For operators, it is essential to avoid operating the machine at high speeds in either forward or reverse. Such practices lead to premature wear on bushings and sprockets. If the tracks are too taut, wear will accelerate. It is critical to maintain a slight amount of slack in the tracks to allow for movement between the iron components, thereby preventing excessive wear.

One of the most important factors in prolonging the lifespan of a bulldozer's undercarriage is maintaining its cleanliness. Removing all debris from within the links and from the frame allows the components to move freely and promotes longer component life.

The causes of wear in dozer track chains can be attributed to several factors:

1. Improper Tension: If the tension of the dozer track chain is too low, it can lead to slack in the chain, increasing sliding friction and impact loads between components. This is particularly damaging to the chain link and pin bushing. Conversely, excessive tension increases pressure between the relative moving parts of the walking mechanism, resulting in greater friction and accelerated wear.

2. Excessive or Uneven Load Distribution: Prolonged use and poor working environments can result in surface wear on the dozer track chain, affecting the smooth operation and transmission efficiency of the chain.

3. Poor Lubrication: The wear and fatigue of the chain, as well as wear and corrosion of the sprocket, are related to lubrication. Insufficient lubrication of the dozer track chain can accelerate wear.

4. Harsh Working Conditions: Operating in wet, dusty, or highly corrosive environments can speed up the wear and corrosion of the dozer track chain, shortening its service life.

5. Metal Fatigue and Friction Wear: Long-term use can lead to wear on the hinge elements of the dozer track chain, which is one of the most common phenomena.

6. Poor Engagement Between Chain and Sprocket: Improper tension of the dozer track chain can lead to poor engagement with the sprocket, further exacerbating wear.

7. Excessive Wear at Chain Links and Rollers: Over-wear due to contact between the track links and the rims of single-sided and double-sided rollers is referred to as "rail scuffing," which can also lead to accelerated wear of the dozer track chain.

8. Poor Quality or Inappropriate Selection of Chains: Using low-quality chains or choosing the wrong specifications can also contribute to increased wear.

9. Severe Wear of Chain Pins: Significant wear on the chain pins can result in the chain jamming and increased wear.

Various factors contribute to the wear of dozer track chains, including improper tension, excessive or uneven load distribution, poor lubrication, harsh working environments, metal fatigue and friction wear, poor engagement between the chain and sprocket, excessive wear between the chain links and rollers, as well as poor quality or inappropriate selection of chains. These factors can significantly impact the lifespan and performance of the dozer track chain.

In the production process of excavator and bulldozer track links, various processes can ensure or enhance the quality of the chains. Here are some key processes:

Material Selection: The use of high-quality steel is fundamental to ensuring track links. For example, 35MnBN material is used for the link plates of bulldozer track links and is treated through quenching and tempering to improve its core performance.

Heat Treatment Process: Heat treatment is a critical step for increasing the hardness and wear resistance of the track links. For instance, the link plates undergo medium-frequency quenching to further enhance their wear resistance. Additionally, track links components typically undergo hardening and tempering to ensure proper mechanical properties. 

Precision Machining Technology: Precision machining technology ensures that the dimensions and fit of each track links component are highly accurate, which improves overall durability and stability. For example, all bushings, pins, and forged link plates are processed with precision to ensure tight and accurate assembly dimensions and sealing performance.

Lubrication Technology: Lubrication technology is also crucial in the production of track links. Lubricating the chains with oil reduces friction between the bushings and pins, allowing them to maintain superior wear resistance even in harsh working environments. Furthermore, regular lubrication can extend the lifespan of the chains.

Flaw Detection Process: The flaw detection process for the track links of excavators and bulldozers is an important step in ensuring chain quality. Flaw detection is primarily performed using magnetic particle testing. This non-destructive testing method applies magnetization to the surface of the components, creating a leakage magnetic field in the defect areas, which attracts magnetic particles to form visible magnetic indications that reveal internal or surface defects in the parts, such as cracks or inclusions.

Magnetic particle testing is a commonly used non-destructive testing method, where magnetization is applied to the surface of the parts followed by the application of magnetic particles. Observing the accumulation of particles at defect sites allows for the identification of cracks or other defects in the parts. This method can detect surface and near-surface defects, ensuring the safety and reliability of the equipment.

 

The role of magnetic particle testing is to ensure the quality and safety of the track links. Given the enormous loads that track links endure during use, even the smallest crack or defect can lead to severe mechanical failure or accidents. Therefore, magnetic particle testing can promptly detect and address these potential defects, extending the lifespan of the chains and ensuring the normal operation of the equipment as well as the safety of the operators.