For a loader, there was a failure inside the gearbox. The customer overhauled the gearbox in a local repair shop. During the test run, the machine could only reverse but not move forward. The specific performance is: when the engine is started, the machine reverses when reverse gear or neutral gear is engaged, and the machine does not move when the first or second gear is engaged.
The loader gearbox is a planetary power shift gearbox. The planetary gears, sun gear and inner ring gear are in constant meshing state. The power transmission is driven by variable speed pressure oil to push the pistons of each gear to compress the master and driven friction plates. To achieve. In the event of the above failure phenomenon, you should first check the change of the transmission oil pressure. Observe the variable speed pressure gauge, the pressure indicator at idling speed is about 1.3Mpa. When the gear is shifted, the pressure gauge pointer drops and quickly returns to the normal value, indicating that the pressure oil has entered the oil cylinders of each gear, and the sealing performance of the oil cylinders of each gear is good. The reason for the gearbox oil supply system can be ruled out.
It can be analyzed that the reason why the loader has only reverse gear and also reverses in neutral gear may be that the reverse gear mechanism is always combined. Because when the first and second gears are engaged, despite the action of the pressure oil, the piston pushes the friction plates of the first and second gears to be normally combined. If the reverse gear mechanism cannot be separated, the forward and reverse powers will cancel each other out. Although the torque converter can output torque, the machine will not move forward or backward.
2020-11
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