After a TY160 bulldozer works continuously for 2 hours at a time, the oil temperature rises to 120～140℃, and the transmission casing emits smoke, and the hydraulic transmission oil is sprayed out from the oil port. The driver immediately stops and gets off the car after discovering the problem. Troubleshoot the cause.

Comprehensive analysis believes that the possibility of variable-speed pump wear is unlikely. Because when the oil temperature increases, the power and driving speed do not decrease, that is, the pressure provided by the variable speed pump to the transmission does not decrease, indicating that there is no problem with the variable speed pump.

The operator parked the bulldozer on a level ground for 20 minutes, then turned off the engine, removed the torque converter oil drain plug, took out the lower part of the torque converter, cleaned it, and measured whether the amount of oil discharged from this hole was greater than 5 L ; The actual amount of oil measured is about 2 L, indicating that there is no internal leakage of the torque converter and the oil return pump is good.

The magnetic coarse filter element at the bottom of the transmission was cleaned, and the fine filter was replaced. The inlet and outlet pressures of the torque converter hydraulic transmission oil radiator were tested with a pressure gauge; the actual measured inlet oil pressure was 0.3 MPa, and the opening pressure of the torque converter regulating valve was 0.2～0.3 MPa, indicating that the oil radiator and the The inside of the tubing is unblocked and not blocked.

This type of bulldozer uses a YT380 hydraulic torque converter. The opening pressure of the safety valve (overflow valve) is 0.75～0.85 MPa, and the opening pressure of the regulating valve (back pressure valve) is 0.2～0.3 MPa. It is used in actual measurement. The opening pressure of the relief valve measured by the oil pressure gauge is 0.81 MPa, and the opening pressure of the back pressure valve is 0.25 MPa, indicating that the torque converter combination valve (safety valve and regulating valve) is working normally.

After excluding the above factors, the transmission was disassembled and inspected, and it was found that the pressure plate of the forward gear in the transmission was cracked, and the threads of 2 of the 9 bolts fixed to the rear case were strained; both the clutch plate and the backing plate Different degrees of wear and deflection, and some backing plates turn dark blue due to long-term high temperature; the free length of the clutch spring cannot reach the standard size.

The machine has been constructed in a high temperature and heavy load environment for a long time, causing the components in the transmission due to high temperature aging, causing cracks, deformation, and flatness error to be out of tolerance, resulting in poor engagement; the clutch spring in the transmission is not properly returned, and the movement is not smooth. When the transmission is required to be in a disengaged state, the clutch is always in a semi-disengaged and semi-engaged state, there is no gap between the clutch friction plate and the backing plate, the separation is not complete, the internal resistance is large, and the high-speed movement between each other produces a lot of The heat causes excessive energy loss in the hydraulic system, and a large amount of hydraulic energy becomes heat energy, which increases the temperature of the hydraulic transmission oil. The pressure plate of the forward gear in the transmission and the friction plate, backing plate and clutch spring that did not reach the standard size were replaced; two bolts were reprocessed; the seals of the wearing parts were replaced, and the parts in the transmission were cleaned and installed. it is good.

When testing the machine, the outside air temperature was 32℃, and the soil was hard soil with a small amount of weathered stones. After 5 hours of continuous operation, the oil temperature rose to 118°C, which was lower than 120°C. The fault was eliminated.