Crawler bulldozers are widely used in engineering construction. The crawler walking device is an important part of the bulldozer. During the operation of the bulldozer, the walking device withstands various pressures and torques during the operation of the bulldozer. Its walking mechanism mainly includes a trolley frame, driving wheels, guide wheels, rollers, and supporting chains. The main functions of wheels (referred to as "four wheels"), crawlers and crawler tensioners are to support the quality of the bulldozer and turn the power transmitted by the transmission mechanism into a driving force to achieve the bulldozer's walking. The walking mechanism of the crawler bulldozer is shown in Figure 1.

　　In the crawler bulldozer walking mechanism, most of the components are rigidly contacted, and lubrication and cushioning measures cannot be adopted. Therefore, the impact load and wear of the components of the walking mechanism are more serious and the failure is more frequent. This article describes the troubleshooting method of 3 cases of crawler bulldozer walking mechanism.

　　1: "Four rounds" nibbling track

　　Failure phenomenon: During the walking or working process of the crawler bulldozer, its crawler chain track and the rims of the drive wheels, guide wheels, rollers and supporting chain wheels produce violent friction and a continuous "creep" sound, resulting in "four wheels" And the accelerated wear of the chain track is a bite rail failure.

　　Causes and troubleshooting methods: The track is wound on the outside of the "four wheels", the track chain track is in direct contact with the wheel body of each wheel, and the chain track does not produce lateral slippage due to the clamping effect of the wheel rim. When assembling the walking mechanism, it should be ensured that the rollers, guide wheels and carrier chain wheels rotate flexibly, and the symmetrical center plane of the "four wheels" coincides with the symmetrical center plane of the track chain track. However, in actual assembly, it is often difficult to meet the above technical requirements, or in the process of bulldozer operation, due to wear, impact, and vibration, the original assembly relationship is changed, resulting in a bite rail failure. The causes and troubleshooting methods of the gnawing fault are as follows.

　　Drive wheel nibbling rail: The drive wheel is installed inside or outside, and it will produce a bite rail failure. The troubleshooting method is as follows: check the symmetrical center plane of the drive wheel and the chain rail, if it is asymmetric, adjust its position on the half shaft; check whether the half shaft is bent or deformed, and if it is bent, straighten it.

　　Guide wheel nibble rail: If the inner and outer rims of the guide wheel are worn inconsistently, the tappet is bent, the elastic force of the tension spring is inconsistent, the lateral clearance of the guide wheels on both sides is inconsistent, etc., will cause the guide wheel to skew, making its symmetrical center plane and " The symmetry center planes of the "four wheels" do not coincide, causing the guide wheels to nibble on the rails. If the tappet is bent, a new tappet should be replaced; if the elastic force of the tension spring is not consistent, the elastic force of the tension spring on both sides should be adjusted.

　　If the lateral gap on both sides of the guide wheel is inconsistent, the lateral gap between the guide wheel and the trolley frame should be adjusted.The adjustment method is as follows: operate the bulldozer to drive on the flat ground for 1~2m to make the crawler track evenly tensioned, and stop to check the guide plate and the trolley frame The gap A between the side plates (see Figure 2a). If the left and right gaps are found to be inconsistent, loosen the fastening bolts of the guide plate (see Figure 2b), and pull out the gasket on the side with the larger gap, add it to the side with the smaller gap or not, until both sides The horizontal gap A is adjusted to the same. When adjusting, be careful not to loosen more than 3 turns when loosening the fastening bolts of the guide plate, to prevent the guide plate from falling off and not easy to install.

　　Roller gnawing rail: The reason for the roller gnawing is mostly due to the offset of its symmetrical center plane. The adjustment method is as follows: use the wire drawing method to check the symmetrical center plane of the roller and determine the roller that needs to be adjusted; loosen it Adjust the connecting bolt between the end cap of the roller and the trolley frame, and adjust its position so that the center of symmetry coincides with the center of symmetry of other rollers.

　　Bracket sprocket bite rail: The cause of the bit sprocket bite rail is related to the offset of the symmetric center plane. The main reason for the offset of the symmetric center plane is the deformation of the support sprocket support and the excessive bearing clearance. The elimination method is as follows: check and adjust the symmetrical center plane of the supporting chain wheel, if the supporting chain wheel is skewed, the supporting chain wheel support should be corrected; if the bearing gap is found to be too large, it should be adjusted.

　　2: Derailment of roller

　　Failure phenomenon: When the crawler bulldozer is driving, working or turning on a lateral slope, the track chain track is laterally dropped from the wheel body such as the roller.

　　Causes and troubleshooting methods: The analysis believes that the failure of track roller derailment is related to track slack and wear of track tensioning device, track roller, and drive wheel. When this fault occurs, the bulldozer should be driven to a flat ground as much as possible, and braking measures should be taken to ensure that the bulldozer stops steadily, and the cause of the fault should be investigated and eliminated one by one, as described below.

　　Track slack: The slack track can cause insufficient tension and cause the rollers to derail. If the crawler track is slack, inject grease into the crawler tensioner as required by the bulldozer instruction manual, and adjust the crawler track until it meets the requirements.

　　Crawler tensioning device damage: leakage in the tensioning cylinder, fatigue deformation of the tensioning spring, etc., will cause the failure of the crawler tensioning device, the degree of tension of the crawler cannot meet the requirements, resulting in the derailment of the roller. If it is determined that the failure of the track tensioner caused the derailment, the failed parts should be repaired or replaced.

　　Roller wheel rim wear: The roller wheel rim is severely worn, which can cause the height of the wheel rim to become smaller and cause the roller to derail. If it is determined that the height of the roller rim is insufficient to cause derailment, the roller body should be repaired or replaced, or the roller assembly should be replaced.

　　Wear of drive wheel teeth: The wear of drive wheel teeth becomes shorter and sharper, which can cause the track roller to derail. If it is determined that the gear teeth of the driving wheel are too short, a new gear wheel gear should be replaced.

　　3: Oil leakage of roller

　　Failure phenomenon: There are traces of oil leakage on the end surface of the wheel body of the roller. After a period of shutdown, a trace of oil will appear on the ground.

　　Causes and troubleshooting methods: The structure of the roller is shown in Figure 3. The wheel body is supported on the wheel shaft through the sleeve and lubricated with gear oil. An O-ring seal and a floating oil seal are used to seal between the wheel body and the wheel shaft to ensure that a certain amount of lubricating oil is stored in the wheel body. If the roller leaks oil and is not handled in time, it will cause the sleeve to ablate until the wheel body is scrapped. The specific causes and elimination methods of oil leakage from rollers are as follows.

　　The reason for the oil leakage of the roller is generally that the fixing bolt of the end cover is loose, the O-ring seal is damaged or aging, and the floating oil seal is seriously worn out. If the fixing bolt of the end cap of the track roller is loose and causes oil leakage, the bolt should be tightened according to the specified torque of the bolt; if the O-ring seal is damaged, or the elasticity is aging, the new O-ring seal should be replaced; if the floating oil seal friction ring The sealing surface is not smooth after being worn, or there is debris between them, which may cause oil leakage. It is necessary to remove the debris and grind the sealing surface; if the oil plug is loose and causes oil leakage, tighten the oil plug.

　　The failure of the crawler bulldozer walking mechanism is generally more intuitive, and the cause of the failure is easier to find, but the consequences of its failure are often more serious. The price of the parts of the crawler walking mechanism is relatively expensive, and the maintenance is difficult. Based on the above, we should pay great attention to the failure of the crawler walking mechanism. Once a failure occurs, it should be checked and eliminated in time to avoid serious consequences caused by the failure.