Bulldozers are one of the mechanical equipment with relatively high technical difficulty and complicated processes in the construction machinery industry. If an excellent driver can master the self-judgment and maintenance of some common faults, it will greatly improve work efficiency and extend the service life of the equipment. So what should I do if the bulldozer breaks down? Let’s take a look at common bulldozer faults and how to deal with them.
1. Unable to start
The bulldozer was unable to start during the process of unsealing the hangar.
After ruling out no power, no oil, loose or blocked fuel tank connectors, etc., it was finally suspected that the PT fuel pump was faulty. Check the AFC air and fuel control device. After opening the air intake pipe and using an air compressor to supply air to the air intake pipe, the machine can start smoothly. If the air supply is stopped, the machine will stall immediately. Therefore, it is concluded that the AFC air and fuel control device is faulty. Loosen the fixing nut of the AFC fuel control device, use an Allen wrench to turn the AFC fuel control device clockwise, and then tighten the fixing nut. When the machine is started again, it can start normally and the fault disappears.
2. Fuel supply system failure
During a seasonal maintenance, the bulldozer needs to be driven out of the hangar, but it cannot be driven on.
Check the fuel tank, there is enough fuel; unscrew the switch at the bottom of the fuel tank, and the car will automatically shut down after 1 minute of starting the car; use the filter inlet pipe to directly connect the fuel tank to the PT pump fuel pipe. If the fuel does not pass through the filter, the car will still not start when it is started again. ;Tighten the manual screw of the oil cut-off solenoid valve to the open position, but it still cannot be started. When reinstalling the filter, turn the fuel tank switch 3 to 5 times and find that a small amount of fuel flows out of the filter inlet pipe, but the fuel will drain out after a while. After careful observation and repeated comparisons, it was finally discovered that the fuel tank switch was not turned on. The switch has a spherical structure. When it is rotated 90°, the oil circuit is connected, and when it is rotated 90° again, the oil circuit is cut off. The ball valve switch has no handle and no limit device. It only exposes the square iron head. The driver mistakenly used the ball valve switch as a throttle switch. After turning it 3 to 5 times, the ball valve returned to the closed position. During the rotation of the ball valve, although a small amount of fuel enters the oil line, the engine can only be started for 1 minute. When the fuel in the line is burned out, the machine will shut down.
3. Oil leakage from winch
Oil leakage occurred at the wire rope winch of the bulldozer during construction. After pulling out all the wire ropes, it was found that the hydraulic oil leaked from the bolts on the winch base, and the leakage was faster when the throttle was increased, and there was almost no oil leakage at idle speed.
Preliminary analysis may be that the bolts were loose or the gaskets were damaged, but after replacing the gaskets and tightening the bolts and testing the machine, the fault persisted. Further analysis of the hydraulic schematic diagram shows that the reason may be caused by poor oil return and high back pressure. So the oil return pipe from the winch to the control valve was replaced, that is, a short oil return pipe was welded to the upper part of the inside of the oil tank, and replaced with a thicker hose than the original oil return pipe, so that the end of the oil return pipe was not connected to the control valve. Directly connect the new oil return short pipe to reduce the oil return back pressure. Tested the machine again and the fault disappeared.
4. The heat engine cannot move
During use, the cold machine started and bulldozed normally. However, after 50 minutes of operation, as the oil temperature gradually increased, the bulldozer became weaker and weaker, and it was even difficult to walk without load. If you stop and rest for 2 hours at this time, start the engine again after the oil temperature drops, and the starting and dozing will return to normal.
During the operation, the engine throttle did not decrease and the speed did not decrease, indicating that the bulldozer’s powerlessness had nothing to do with the engine. Preliminary analysis believes that the cause is a lack of oil in the torque converter, blockage of the oil circuit, or failure of the transmission and steering clutch. Check that the torque converter is normal; loosen the exhaust screw on the variable speed fine filter and find that there are bubbles in the discharged oil, which cannot be discharged for a long time. The analysis believes that if there is a place where air enters, both the cold engine and the hot engine should have air inlet, causing the machine to work normally in the cold state. It can be concluded that the sealing condition of the low-pressure oil circuit is in good condition. The air intake in the high-pressure oil circuit of the thermal engine causes the machine to be unable to move. This should be caused by excessive vacuum in the low-pressure oil circuit.
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Post time: Mar-07-2024