Analysis of the causes of gearbox clutch friction plate burnout
The main cause of clutch friction plate burnout
(1) Oil temperature is too high
According to the oxidation degree of the surface of the transmission parts and the hydraulic oil, it is judged that the oil temperature of the hydraulic system is too high. The excessive oil temperature is caused by the hydraulic pump, oil filter, cooler and other components of the hydraulic system and the hydraulic oil. Due to the excessive oil impurities in the hydraulic system, If too much, the oil filter will be clogged, the circulation of the hydraulic system will be blocked, poor cooling and too fast circulation will increase the oil temperature; if the oil temperature is too high, the internal rubber seal of the transmission clutch will age, deform, and crack, affecting the performance and life of the clutch. Lower, resulting in poor meshing between the main parts of the clutch and the moving parts, slippage between the main parts and the moving parts, incomplete clutch separation, and increased frictional resistance, thereby accelerating the severe wear of the clutch friction plates.
(2) Improper use of hydraulic oil
According to the degree of oxidation and deterioration of the gearbox residual oil, it is confirmed that the hydraulic oil is improperly selected. In the hydraulic system, hydraulic oil plays the role of transmitting power, as well as lubricant and cooling. Improper use of hydraulic oil will directly affect the working quality of the hydraulic system. . Practice has proven that 80% of hydraulic system failures are caused by oxidative deterioration of hydraulic oil. Valve components in hydraulic systems, such as variable speed pumps, control valves and lubrication valves, require very precise clearances. The components are equipped with resistance holes, control valve holes, lubricating oil holes, and hydraulic oil inlets. Once the hydraulic oil is oxidized or mixed with a large amount of impurities, these oil holes will be blocked, and the flow of hydraulic oil will be hindered, making these parts unable to work. normal work.
(3) Pressure is too low
If impurities in the hydraulic oil enter the transmission, it will cause the oil inlet and oil holes to become clogged. If impurities in the oil enter the clutch piston and hydraulic cylinder, the sealing ring will get stuck in the hydraulic cylinder and cannot rise outward. Therefore, the sealing between the piston sealing ring and the hydraulic cylinder is not tight, causing leakage of pressure oil, reducing the operating oil pressure of the clutch, causing slippage and ineffective action. This in turn causes serious wear of the clutch friction plates, poor engagement, and insufficient lubrication of the clutch main and driven discs, aggravating the wear of the clutch friction plates. Clutch plate.
2. Precautions
In order to extend the service life of the bulldozer gearbox clutch, based on our long-term work experience, we must do the following:
(1)Cleaning system
When installing a new transmission, the hydraulic pump, oil filter, torque converter, cooler, operating valve, etc. of the main hydraulic system should be strictly cleaned. It is preferred to use a cleaning fluid of the same grade as the torque converter. It is prohibited to use kerosene or diesel oil for cleaning of No. 8 hydraulic transmission oil. When cleaning, increase the flow rate of the cleaning fluid as much as possible to wash away mechanical impurities and oil stains in the hydraulic system pipelines. After cleaning is completed, the cleaning fluid should be removed in a warm state.
(2) Choose the correct oil
According to the requirements of the instruction manual, the gearbox and chassis hydraulic system use No. 8 hydraulic transmission oil. The selected hydraulic oil should have good low-temperature fluidity, suitable high-temperature viscosity, good thermal oxidation stability and foam resistance, as well as good anti-friction and corrosion resistance. It is prohibited to use different brands of hydraulic oil. The oil must be strictly filtered before refueling to prevent mechanical impurities, dust, moisture, emulsions, etc. from invading the hydraulic system.
(3) Control system pressure
Before operating the machine, the pressure of the hydraulic system should be strictly checked, that is, use a pressure gauge to test the pressure entering the transmission control valve. The standard value of the transmission II and III engagement pressure. The transmission clutch is at the pressure regulating valve (2.5MPa ± 0.2MPa), I gear It is set under the action of lock-up clutch oil pressure (1.25MPa±0.1MPa) and lubrication valve oil pressure (0.1MPa±0.025). MPa). If the measured clutch pressure is lower than the standard value, first check the transmission control valve to determine whether the gap between the transmission control valve stem and the valve body hole is too large; if the spring force of the pressure regulating valve and pressure reducing valve is too weak, then The O-ring on the shift operating valve stem is damaged. If damaged, it should be replaced and adjusted in time. When the pressure reducing spring force of the pressure regulating valve is insufficient, a washer of appropriate thickness can be added to the spring seat to adjust the working oil pressure. And reinstall it for testing. If the measured pressure is still lower than the standard value, the transmission valve assembly must be replaced.
(4) Reasonably adjust the meshing clearance
There is a pair of helical bevel gears at the output end of the transmission, which transmits power to the bottom bracket of the rear axle box. Therefore, the correct degree of meshing has a great impact on the noise, service life and working performance of the entire machine. It should be removed before installation. From the large bevel gear on the old main engine, a new pair of large bevel gears are installed on the central drive shaft and tightened with bolts; the backlash of the bevel gear pair is adjusted to 0.25-0.33mm through speed-regulating gaskets, and the meshing impression is maintained. This bevel gear must be used in pairs.
(5) Maintenance
Maintaining good maintenance and upkeep is an important prerequisite to ensure production safety, maximize the performance of the transmission clutch, and extend its service life. Drivers should carry out daily maintenance seriously and strictly, discover and eliminate minor faults in time, and avoid accidents. For newly manufactured bulldozers or bulldozers that have just been overhauled, the oil should be cleaned out after trial operation or 100 hours of operation, and No. 8 hydraulic transmission oil should be added again. Thereafter, the working oil should be replaced every 1000 hours. In daily work, the hydraulic pressure and oil temperature of the hydraulic system should be observed to prevent the oil pressure and oil temperature from being too low and being unable to continue working. Regularly check the quality of hydraulic oil and keep the hydraulic system and hydraulic oil clean. If an abnormality is found, the cause should be checked in time and the fault should be eliminated to ensure that the bulldozer gear clutch remains in good working condition.