The hydraulic mechanical transmission system of the forklift is an important part of the entire vehicle. After long-term use of some internal combustion forklifts, the hydraulic mechanical transmission system will have some common failures, such as: insufficient output power, difficult start, slow shift response; oil Excessive temperature and torque converter does not work.
Failure analysis
If it is found that the forklift has insufficient power, difficult climbing, slow shift response, and the load lifting operation is normal, first use a pressure gauge to check the system pressure. If the specified pressure value is not reached, the reason may be: Excessive wear of gears and pump body causes excessive wear of the gears and pump body of the compensation pump, which increases leakage in the compensation pump; poor cleanliness of the oil causes clogging of the oil circuit, which causes the compensation to vacuum.
If the oil temperature is too high, the usual reason is: the oil supply is insufficient due to the blockage of the compensation pump, causing the clutch dry friction to cause the oil temperature to be too high; the oil pressure in the torque converter is lower than the adjustment pressure of the main pressure valve, so that The outlet pressure of the torque converter is too low; the oil grade is not correct; the internal components of the torque converter are damaged, so that only a small part of the engine's power is transferred to the turbine, and the excessive reactive power causes the oil temperature to rise sharply.
If the torque converter does not work from the observation hole of the torque converter, you should first check the oil inlet and return conditions of the torque converter. If there is no oil return, and the forklift truck is running cold and the car is hot If the driving is difficult, the cause of the failure is to compensate the serious wear or damage of the pump; if the torque converter has no power output and sometimes does not work during operation, the cause of the failure is clogged oil path, damaged inner sleeve of the guide wheel seat, or loose nut of the guide wheel seat.
Troubleshooting
From the above analysis, it can be seen that the faults of the hydraulic mechanical transmission system of the forklift are mainly three links: the oil circuit, the torque converter and the compensation pump. Therefore, when troubleshooting, you should first consider cleaning the oil circuit, replacing the oil and oil filter as required; then check the three links of the torque converter and the compensation pump. Therefore, when troubleshooting, you should first consider clearing the oil circuit and replacing the oil and oil filter as required; then check the guide wheel, guide wheel seat and overrunning clutch of the torque converter for damage; and finally check the compensation pump for wear , And repair or replace damaged components. The dust and dirt on the surface of the oil radiator must also be cleaned. After the above treatments are performed, the fault can be generally eliminated.
When overhauling the drive train, the following inspections should be noted; the coaxiality error of the engine flywheel, torque converter and torque converter housing should not be greater than 0.2mm; the dynamic unbalance of the connecting disc should be less than 30g·cm; the end face of the engine flywheel housing and The end face of the torque converter shell relative to its axis is no more than 50UM; there should be a gap of 1.0-1.5mm between the torque converter fork and the end face of the compensation pump gear.
