How to prevent the high oil temperature of hydraulic torque converter of loader?

During the operation of a loader (belonging to the ZL series), the oil temperature of the torque converter continues to exceed 120°C and the following phenomena occur, such as oily smoke from the fuel filler, weak drive, speed reduction, abnormal noise of the variable-speed pump, and variable-speed pressure Too low. Too high oil temperature can easily cause the oil to oxidize and deteriorate, reduce its viscosity, reduce transmission and lubrication functions, accelerate internal leakage, component wear, rubber seal failure, and even cause mechanical accidents. The main reasons for the high oil temperature of the torque converter are: the use of unqualified hydraulic transmission oil, the decrease of oil viscosity or oxidation causes the oil transmission and lubrication ability to decrease; the filter screen is blocked; the rotating oil seal fails; the connecting bolts are loose; Blockage of the device and pipeline; long-term overload work; severe wear of the friction plate; slipping of the overrunning clutch; failure of the cooling system, etc. The measures to prevent excessive oil temperature in the torque converter are as follows: 1. Reasonable selection and use of hydraulic transmission oil For example, the oil used for the torque converter of XGMA ZL40 and ZL50 loaders is No. 22 gas turbine oil (SYB1201-60HU-22); the oil used for LIUGONG models is AF8 (namely No. 8) hydraulic transmission oil. The hydraulic transmission oil should also be selected according to the temperature characteristics of the construction season, so that it has suitable oxidation resistance, viscosity and viscosity-temperature characteristics, and quantitatively filled. The filling capacity of the torque converter fuel tank of XGMA ZL40 and ZL50 loaders is 45L, and the filling capacity of the torque converter fuel tank of the Liugong model is 42L and 45L. 2. strengthen maintenance For example, during the construction of a ZL50 loader, the oil temperature of the torque converter continued to exceed 120°C, accompanied by abnormal noise of the variable speed pump. It was found that the filter screen was blocked and the oil suction resistance of the variable speed pump increased, resulting in increased oil absorption energy consumption and transmission oil. Insufficient supply caused the oil temperature of the torque converter to rise. At the same time, a hose was found and the fault was rectified. For loaders equipped with a fine oil filter, the fine oil filter must be checked regularly to ensure smoothness. Also check the front and rear axle output shaft oil seals and replace them in time to prevent oil leakage. Always check the engine cooling water volume and the tension of the fan tape to ensure that there is sufficient cooling water and ventilation. 3. pay attention to the degree of part wear and assembly quality To maintain a good technical condition of the variable speed pump. When the pump body is touched by hand and the temperature is much higher than the box body temperature, it should be overhauled. The gap between the end faces of the two gears and the pump cover should be 0.150～0.200mm, and the difference between the width of a pair of gears should not be more than 30mm in the maximum width (ZL50 LIUGONG loader), and the surface of the parts should not have obvious Scratches and grooves. The gears must be assembled in pairs and kept in good contact, operate flexibly, and must not jam. It is necessary to prevent the gear friction and internal leakage throttling during the operation of the variable speed pump from causing the oil temperature to rise. When overhauling the transmission, focus on checking the friction plate. There should be no peeling, cracks, adhered wear debris and dust, and the friction plate should be firmly bonded to the steel plate. Secondly, pay attention to detecting the thickness of the main and driven friction plates. The maximum wear of the friction plates of the direct gear drive plate assembly of ZL50 loader transmission and the reverse gear and I gear drive plate assembly is 0.300mm. If the friction plate is too worn, it is easy to slip, and the friction plate is too thick or the assembly gap is too small to cause interference. It is necessary to maintain a good matching clearance of the variable speed valve. If the clearance is too large, it is easy to squeeze out the pressure oil from the gap, causing throttling loss and increasing the oil temperature. The pressure adjustment of the variable speed valve should be correct to prevent the low piston thrust caused by the low variable speed pressure, the main and follower friction plates are not tightly engaged and slip, and the friction heat causes the oil temperature to rise. After the torque converter is assembled, the rotating parts should be able to rotate freely, and the turbine group should be rotated by hand. The first and second turbines should rotate flexibly and without jamming to prevent collision and interference when the components are rotating, which may cause friction, heat, and oil. Temperature rise and power loss. In addition, each oil seal and sealing ring must not be damaged, and the oil seal ring must not be stuck. If the bearing is damaged, it should be replaced in time to prevent friction caused by the deflection of the moving part due to the damage of the bearing. Check whether the overrunning clutch is slipping and jamming, and prevent it from changing the direction of the fluid flow and causing mixed flow to cause the oil friction to heat up. And maintain normal oil pressure at the inlet and outlet of the torque converter. In the oil-filled no-load test of Liugong’s ZL50 loader twin-turbo hydraulic torque converter, at an input speed of 1500r/min and an oil temperature of 80～100℃ for 20min, the inlet oil pressure of the torque converter should be kept at 0.549MPa, the outlet oil pressure should be maintained at 0.280～0.450MPa, and the oil drainage volume should not exceed 1.5L/min. 4. Prevent the influence of man-made and environmental factors Do not avoid long-term overload operation. When there is a lot of dust on the construction site, flush it with a high-pressure water gun in time.