The hydromechanical transmission system of forklift truck is an important part of the whole vehicle. After long-term use of some internal combustion forklifts, some common faults will appear in the hydromechanical transmission system, such as insufficient output power, difficult starting and slow shift response; The oil temperature is too high and the hydraulic torque converter does not work.
fault analysis
In the process of use, if the forklift is found to have insufficient power, difficult climbing, slow shift response, and the load lifting works normally, first use the pressure gauge to detect the system pressure. If the specified pressure value is not reached, the reason may be: the gear and pump body of the compensation pump are excessively worn, resulting in excessive wear of the gear and pump body of the compensation pump, resulting in increased leakage in the compensation pump; The cleanliness of the oil is too poor, which leads to the blockage of the oil circuit and makes the compensation empty.
If the oil temperature is too high, the common reasons are: the oil circuit is blocked, resulting in insufficient oil supply of the compensation pump, making the clutch dry friction and causing 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; Incorrect oil grade; The internal components of the torque converter are damaged, so that only a small part of the power of the engine is transmitted to the turbine. The excessive reactive power causes the oil temperature to rise sharply.
If it is observed from the observation hole of the hydraulic torque converter that the hydraulic torque converter does not work, first check the oil inlet and return of the hydraulic torque converter. If there is no oil return, and the forklift runs normally in cold and difficult in hot, the fault reason is that the compensation pump is seriously worn or damaged; If the torque converter has no power output and sometimes works and sometimes does not work, the fault causes are oil circuit blockage, damage to the inner sleeve of the guide wheel seat or loose nut of the guide wheel seat, etc.
Fault handling
From the above analysis, it can be seen that the faults of hydraulic mechanical transmission system of forklift are mainly oil circuit, hydraulic torque converter and compensation pump. Therefore, when troubleshooting, first consider cleaning the oil circuit and replacing the oil and oil filter as required; Then check the three links of hydraulic torque converter and compensation pump. Therefore, when troubleshooting, first consider cleaning the oil circuit and replacing the oil and oil filter as required; Then check whether the guide wheel, guide wheel seat and overrunning clutch of the hydraulic torque converter are damaged; Finally, check whether the compensation pump is worn, and repair or replace the damaged components. The dust and dirt on the surface of the oil radiator must also be cleaned. After the above treatment, the fault can generally be eliminated.
When repairing the transmission system, pay attention to the following inspections; The coaxiality error of engine flywheel, torque converter and torque converter housing shall not be greater than 0.2mm; The dynamic unbalance of the connecting plate shall be less than 30g · cm; The end runout of the end face of the engine flywheel housing and the end face of the torque converter housing relative to their axis shall not be greater than 50um; There should be a gap of 1.0-1.5mm between the shift fork of torque converter and the gear end face of compensation pump.
