There are many reasons for high temperature of hydraulic oil, but for hydraulic excavators, the main reasons for high temperature of hydraulic oil are as follows:
1. High temperature caused by local pressure relief. If the hydraulic cylinder of hydraulic actuator leaks, it will cause high temperature of hydraulic oil.
2. High temperature caused by failure of two check valves of main control valve return oil. The main control valve of hydraulic excavator generally has two check valves with different pressures, one of which is 45KN. The hydraulic oil returns to the oil tank directly through the check valve. A pressure of 30KN, the hydraulic oil through the check valve, and then through the hydraulic oil radiator cooling back to the tank, to ensure the normal working temperature of the hydraulic oil. If the 45KN one-way valve remains normally open due to fault, or the 30KN one-way valve remains normally closed due to fault or the opening is not large enough, the hydraulic oil to the main control valve will return to the oil tank without sufficient cooling or cooling, causing high temperature of the hydraulic oil.
3. High temperature caused by fault of hydraulic oil radiator fan motor. The hydraulic oil radiator fan motor is controlled by a solenoid valve. When the hydraulic oil temperature exceeds 70 ℃, the solenoid valve accelerates the speed of the motor through power on or power off, so as to accelerate the cooling of the hydraulic oil. If the fan motor has internal leakage, it will cause the fan speed to drop, resulting in high temperature of hydraulic oil.
4. High temperature caused by solenoid valve fault of hydraulic oil radiator fan motor. When the temperature of the hydraulic oil exceeds 70 ℃, the solenoid valve accelerates the speed of the motor through power on or power off, so as to accelerate the cooling of the hydraulic oil. If the solenoid valve fails and can not work normally, when the fan needs to run at high speed, the motor can not get the command, which will also cause the high temperature of the hydraulic oil.
5. High temperature caused by blockage of hydraulic oil radiator. If the hydraulic oil radiator is partially blocked, the amount of hydraulic oil flowing through the radiator will be reduced, and because the radiator is blocked, the return oil amount of the 45KN one-way valve of the main control valve return oil will increase, and the hydraulic oil will directly return to the oil tank without cooling down, causing high temperature of the hydraulic oil.
