Analysis of the Causes of Burning of the Transmission Clutch Friction Plate
Main Causes of Burning of the Clutch Friction Plate
(1) Excessive Oil Temperature
According to the degree of oxidation of the transmission parts and hydraulic oil, it is judged that the hydraulic system oil temperature is too high. The hydraulic pump, oil filter, cooler and other parts and hydraulic oil in the hydraulic system cause excessive oil temperature. Due to excessive impurities in the hydraulic system, the oil filter is blocked, the hydraulic system circulation is not smooth, the cooling is poor and the circulation is too fast, which causes the oil temperature to rise; the increase in oil temperature and the aging, deformation and cracking of the rubber seal inside the transmission clutch reduce the performance and life of the clutch, causing poor meshing of the main and moving parts of the clutch, slippage between the main and moving parts, incomplete clutch separation, increased friction resistance, and accelerated serious wear of the clutch friction plate.
(2) Improper use of hydraulic oil
According to the degree of oxidation and deterioration of the residual oil in the transmission, it can be confirmed that the hydraulic oil is improperly selected. In the hydraulic system, the hydraulic oil plays the role of transmitting power, and at the same time plays the role of lubrication and cooling. Improper use of hydraulic oil will directly affect the working quality of the hydraulic system. Practice has shown that 80% of hydraulic system failures are caused by oxidation and deterioration of hydraulic oil. The speed change pump, control valve, lubrication valve and other valve components in the hydraulic system require very precise matching clearances. There are resistance holes, control valve holes, lubricant holes, hydraulic oil inlets, etc. on the components. Once the hydraulic oil is oxidized or mixed with a large amount of impurities, these oil holes will be blocked, the flow of hydraulic oil will be hindered, and these components cannot work normally.
(3) The pressure is too low
If impurities in the hydraulic oil enter the gearbox, it will cause the oil inlet and oil holes to be blocked. If impurities in the oil enter the clutch piston and hydraulic cylinder, the seal ring will be stuck in the hydraulic cylinder and cannot rise outward. Therefore, the seal between the piston seal ring and the hydraulic cylinder body is not tight, causing the pressure oil to leak out, reducing the clutch working oil pressure, causing slipping and poor work, which will cause serious wear of the clutch friction plate, poor engagement, and insufficient lubrication of the clutch master and slave plates, which will aggravate the wear of the clutch. Clutch plate.
2. Preventive measures
In order to extend the service life of the bulldozer transmission clutch, according to our long-term work experience, the following points must be achieved:
(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. The best cleaning fluid is No. 8 hydraulic transmission oil of the same brand as the torque converter. It is strictly forbidden to use kerosene and diesel for cleaning. When cleaning, try to increase the flow of the cleaning fluid to flush away the mechanical impurities and oil stains in the hydraulic system pipeline. After cleaning, the cleaning fluid should be removed in a warm state.
(2) Correct selection of oil
According to the requirements of the instruction manual, the transmission and chassis hydraulic system use No. 8 hydraulic transmission oil. The selected hydraulic oil should have good low-temperature fluidity, appropriate high-temperature viscosity, good thermal oxidation stability and anti-foaming properties, as well as good anti-friction and corrosion properties. It is forbidden to use hydraulic oils of different brands. 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 hydraulic system pressure should be strictly checked, that is, the pressure entering the transmission control valve should be detected with a pressure gauge, and the standard value of the clutch engagement pressure of the transmission II and III gears should be set under the action of the pressure regulating valve (2.5MPa±0.2MPa), the oil pressure of the I gear lock clutch (1.25MPa±0.1MPa), and the oil pressure of the lubrication valve (0.1MPa±0.025MPa). If the measured clutch pressure is lower than the standard value, the speed control valve should be checked first to determine whether the gap between the valve stem and the valve body hole of the speed control valve is too large; whether the spring force of the pressure regulating valve and the pressure reducing valve is too weak; whether the O-ring on the speed operating valve stem is damaged. If damaged, it should be replaced and adjusted in time. When the pressure regulating valve pressure reducing spring force is insufficient, a gasket of appropriate thickness can be added to the spring seat to adjust the working oil pressure. Reinstall and test. If the measured pressure is still lower than the standard value, the speed valve assembly must be replaced.
(4) Reasonable adjustment of meshing clearance
A pair of helical bevel gears are used at the transmission output end to transmit power to the central shaft of the rear axle box. Therefore, the correctness of the meshing degree has a great impact on the noise, service life and working performance of the whole machine. Before installation, the large bevel gear should be removed, and a new pair of large bevel gears should be installed on the central transmission shaft and fastened with bolts; the tooth gap of the bevel gear pair should be adjusted to 0.25-0.33mm through the speed regulating gasket, and the meshing indentation should be maintained; this bevel gear must be used in pairs.
(5) Maintenance
Maintaining good maintenance and care is an important prerequisite for ensuring production safety, giving full play to the performance of the transmission clutch, and extending its service life. The driver should perform daily maintenance carefully and strictly, and promptly discover and eliminate minor faults to avoid accidents. For newly manufactured bulldozers or bulldozers that have just undergone overhaul, the oil should be cleaned after trial operation or 100 hours of operation, and No. 8 hydraulic transmission oil should be added again. The working oil should be replaced every 1000 hours thereafter. In daily work, the oil pressure and oil temperature of the hydraulic system should be observed at any time to prevent the oil pressure from being too low and the oil temperature from being too high and continuing to work. Check the quality of the hydraulic oil regularly to keep the hydraulic system and hydraulic oil clean. If any abnormal situation is found, the cause should be checked and the fault should be eliminated in time to ensure that the bulldozer gear clutch remains in good working condition.