When the bulldozer is performing earthwork leveling, the driver suddenly finds that his right track is loose, and when he gets out of the vehicle, he finds that the right track pin (outside) is abnormally worn, and the guide wheel moves 6-7 cm along the carriage. Due to the large slack of the track, in order to avoid track derailment and abnormal wear of the track pin during the steering process, the driver should immediately choose the nearest flat road for overhaul.

　　First, use an oil gun to fill the grease through the oil filling point of the tensioning hydraulic cylinder. The grease filling is smooth and the tensioning hydraulic cylinder does not move (there is no overflow of grease). From this preliminary analysis, it may be that the tensioning hydraulic pressure Cylinder failure. The cause of this failure may be the failure of the oil seal inside the tensioning hydraulic cylinder. In view of the characteristics of the pretension of the tensioning hydraulic cylinder of the tracked vehicle, in order to avoid accidents, the vehicle should be repaired immediately.

　　After the disassembly, it was found that the oil seal of the tensioning hydraulic cylinder is seriously aging and damaged (it can be broken off by hand), and it is found that the rear end of the piston and the inner wall of the tensioning hydraulic cylinder are heavily corroded (the lack of grease at this location is natural corrosion) . After replacing the oil seal and loading the vehicle, the tensioning hydraulic cylinder acts normally, and the track tightness returns to normal.

　　According to the on-site dismantling situation: due to the long service life of the vehicle and the aging of the hydraulic seal of the tensioning cylinder, the oil seal is damaged due to the left and right thrust during the operation of grease filling, vehicle driving and steering, and the damaged oil seal The grease cannot be reliably sealed, resulting in seal failure. The high-pressure grease sealed at the front of the piston enters the rear end of the piston through the broken oil seal. The pressure-relief hydraulic cylinder piston runs reversely under the push of the pretension spring, resulting in guidance The wheel retracts under the pressure of the reaction force of the track, which eventually causes the track to relax. In view of the serious aging phenomenon of the piston oil seal of the right tensioning hydraulic cylinder, the piston oil seal of the left tensioning hydraulic cylinder was also replaced (the oil seal also has problems of aging and damage).

　　Through this fault analysis and elimination, the majority of drivers are reminded that the following points should be noted for the use and maintenance of this type of bulldozer:

　　1: Regularly check the tightness of the crawler track, according to the tightness situation, grease the tension hydraulic cylinder at any time, note that the amount of one-time filling should not be too much.

　　Compared with the crawler hydraulic excavator, crawler bulldozers have more frequent walking operations, so the walking system wears more seriously, especially the drive teeth, rollers, guide wheels, carrier sprockets, track pin sleeves (for chain rail connection ) Etc. directly contact the friction parts. When the tensioning hydraulic cylinder is not filled with grease, the crawler track will be slack, which will cause the crawler track to easily derail, the vehicle will be noisy when driving, and the driving teeth will have a large impact on the track pin sleeve when the forward and reverse gears are switched. And other issues. At the same time, the track is not easy to be over-tight, and over-tightness can easily cause abnormal wear of the track, drive teeth, and guide wheels, and the track pin sleeves are deformed due to long-term extension. Therefore, the driver is often required to check and adjust the tightness of the track.

　　2: In order to avoid the stuck phenomenon when the piston is running due to the corrosion of the tensioning hydraulic cylinder piston and the inner wall of the tensioning hydraulic cylinder, the oil injection nozzle of the tensioning hydraulic cylinder can be disassembled regularly, and the mode of slow-speed gear shifting is adopted, and the reaction of the crawler is used Force the tensioning hydraulic cylinder to retract, and then refill the tensioning hydraulic cylinder with grease. In the implementation process, unrelated personnel should stay away from the position of the oil injection nozzle, so as to avoid the grease in the tension hydraulic cylinder being suddenly squeezed and splashing out and hurting people.

　　3: Once the sudden slack of the track is found, the driver must stop immediately for maintenance, so as not to cause mechanical accidents or even accidents to expand.

　　4: The pretension spring of the tensioning hydraulic cylinder has a great preload force, and special tools are needed for installation. Therefore, for construction machinery users and maintenance units that lack maintenance experience, it is best to choose a service provider or a qualified maintenance unit for overhauling the tensioning hydraulic cylinder to avoid accidents caused by improper disassembly.