Diagnosis and elimination of high transmission oil

2022-08-12
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Diagnosis and elimination of high transmission oil temperature of bulldozer

a TY160 bulldozer produced by Shantui factory once, after working for 2 hours continuously, the oil temperature rose to ℃, and the transmission shell smoked, and the hydraulic transmission oil spewed out from the oil port, but the driving speed of the transmission did not decrease, so the driver had to shut down the engine and stop working, and continue the construction after the oil temperature decreased. This has seriously affected the progress of construction

the oil circuit system of the transmission and torque converter of the machine is shown in the attached figure

during troubleshooting, the following steps were taken

first of all, pay attention to the following matters in operation: G will exempt the state-owned capital income service of backbone coal enterprises from using small throttle for a long time in the next three years; After loosening the hard soil with a scarifier, push it, and the pushing distance should not be too long; Under the condition that the bulldozer does not stall, control the amount of bulldozing each time, and reasonably lift and lower the blade

then, add the oil in place according to the scale calibrated on the transmission dipstick, and choose the Great Wall brand 8 hydraulic transmission oil with good oil quality. The ventilation conditions are improved, that is, cover plates are installed on both sides of the engine and sealed, so that the exhaust fan can forcibly remove the heat around the engine and transmission, and take away part of the oil temperature

from the phenomenon analysis, it is considered that the possibility of wear of variable speed pump is small. Because when the oil temperature rises, the power and driving speed do not decrease, that is, the pressure supplied by the variable speed pump to the transmission does not decrease, which means that the variable speed pump has no problem

check the internal leakage of the torque converter and the failure of the oil return pump, that is, stop the engine after the bulldozer is parked at a level for 20min, remove the oil drain plug of the torque converter, take out the filter element at the lower part of the torque converter, clean it, and measure whether the microcomputer fully automatic control oil discharged from this hole is greater than 5L; The actual amount of oil is about 2L, indicating that there is no leakage inside the torque converter and the return oil pump is good

cleaned the magnetic primary filter element at the bottom of the transmission and replaced the secondary filter. The inlet and outlet pressures of the torque converter hydraulic transmission oil radiator were measured with a pressure gauge; The actual measured inlet oil pressure is 0.3MPa, while the opening pressure of the regulating valve (back pressure valve) of the torque converter wire torsion tester is 0 3 MPa, indicating that the interior of oil radiator and oil pipe is unblocked without blockage

ty160 bulldozer uses yt380 hydraulic torque converter, and the opening pressure of its safety valve (overflow valve) is 0 85 MPa, the opening pressure of the regulating valve (back pressure valve) is 0 3 MPa. During the actual measurement, the opening pressure of the overflow valve measured by the oil pressure gauge is 0.81 MPa (that is, the pressure at point C in the figure), and the opening pressure of the North pressure valve is 0.25 MPa (that is, the pressure at point D in the figure), indicating that the combined valve of the torque converter (safety valve and regulating valve) works normally

after eliminating the above factors, the transmission was disassembled and inspected, and cracks were found on the pressure plate of the forward gear in the transmission, and the threads of two of the nine bolts fixed to the rear box were strained; Clutch plates and backing plates are worn and flexed to varying degrees, and some backing plates turn dark blue due to long-term high temperature; The free length of the clutch spring can not reach the standard size. The clutch spring for forward and reverse gears should be 59mm, measured 57mm, and the clutch spring for second and third speeds should be 41.3mm, measured 40.3mm. For this reason, the pressure plate of the forward gear in the transmission and the friction plate, backing plate and clutch spring that failed to reach the standard size were replaced, two bolts were reprocessed, the seals of worn parts were replaced, and all parts and components in the transmission were cleaned and reinstalled. Before installation, use an air pump to check whether the pistons of each cylinder of the transmission move freely and whether the assembly meets the requirements; Results when the air pump pressure is 0.4MPa, its stroke is 3 mm, indicating that the transmission clutch is completely and effectively separated. During the test run, the outside temperature is 32 ℃, and the soil package pressure tester is used to conduct static compression tests on the packaging buffer materials, packaging boxes or packages to determine the force deformation characteristics of the materials or packages. The properties are hard soil with a small amount of weathered stones. After continuous operation for 5 hours, the oil temperature rises to 118 ℃ and is lower than 120 ℃. After 3 months of operation, the machine has not experienced the phenomenon of excessive oil temperature

after troubleshooting, the analysis shows that the fundamental reason for the high temperature of the oil is that the machine has been operated in a high temperature and heavy load environment for a long time, which makes the components in the transmission crack and deform due to high temperature aging, and the flatness error is out of tolerance, resulting in poor connection; The clutch spring in the transmission has poor return and poor movement. When the transmission is required to be in the disengaged state during operation, the clutch is always in the semi disengaged and semi engaged state. There is no gap between the clutch friction plate and the backing plate, the separation is not complete, and the internal resistance is large. Due to the high-speed movement between them, a lot of heat is generated, resulting in excessive energy loss in the hydraulic system, and a large amount of hydraulic energy becomes heat energy, Thus, the temperature of hydraulic transmission oil increases

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