For the excavator, when the hydraulic oil temperature is 50-80 ° C, the viscosity, lubricity and wear resistance of the hydraulic oil are in the best state, and the working efficiency is the highest. When the temperature of the hydraulic oil exceeds 95 °C, the efficiency of the excavator decreases, the movement is inaccurate and slow, and the excavator cannot work when it is serious.

High temperature of hydraulic oil is a very headache. It not only causes the working efficiency of the excavator to drop, but also seriously impairs the performance of the main pump. If the hydraulic components of the whole vehicle are in a long-term high temperature state, its life will be shortened sharply.

How to solve the problem of excessive hydraulic oil temperature? It can be started from hydraulic oil radiator, hydraulic system, hydraulic oil, driver operation.

 

Whether the hydraulic radiator is blocked

The working environment of the excavator is relatively harsh. It is rainy and muddy on sunny days, and there are insects in the spring. The periphery of the radiator of the hydraulic system is easily clogged, which causes poor heat dissipation of the hydraulic system. Therefore, the hydraulic system radiator should be cleaned regularly, and a layer of air filter should be installed outside the radiator.

 

Inside the radiator, after a long period of wear and carbonization of the hydraulic oil, it also produces some solid impurities like a water tank. These impurities accumulate inside the radiator and, in severe cases, completely block the internal piping.

 

Check whether the internal pipe of the hydraulic oil radiator is blocked. You can use the infrared thermometer to detect the temperature of the oil inlet and the outlet of the hydraulic oil radiator. If the temperature difference is not large, the internal blockage of the hydraulic oil radiator has occurred. It is also possible to install a pressure gauge at the inlet and outlet of the hydraulic oil radiator to check the pressure difference of the oil passage. If the pressure difference is less than 0.12 MPa, it is normal; if it is higher than 0.12 MPa, it indicates that the hydraulic oil radiator is seriously blocked. It is dredged.

 

Is the hydraulic system faulty?

 

As we all know, in order to avoid the pressure of the hydraulic oil radiator is too high, a back pressure valve and a bypass valve are provided at the oil inlet. The pressure of the bypass valve is set to 0.45 MPa. When the pressure of the hydraulic oil radiator is greater than 0.45 MPa, the bypass valve is opened, and part of the hydraulic oil is directly returned to the oil tank without passing through the hydraulic oil radiator. The pressure of the back pressure valve is 0.25 MPa to ensure a certain back pressure of the main circuit of the system, so as to avoid the vacuum generated when the hydraulic system works, to ensure the stability of the oil return, and to prevent damage to the hydraulic oil radiator caused by excessive oil return impact.

 

When the oil temperature of the excavator hydraulic system is high, the back pressure valve and the bypass valve should be detected for malfunction. If the bypass valve is in the normally open state, or the back pressure valve is in the closed state, the hydraulic oil does not flow back to the hydraulic oil tank through the cooling of the hydraulic oil radiator, which may cause the hydraulic oil temperature to be too high.

 

In addition, the clearance between the valve stem of the multi-way valve and the valve hole is too large, the gap between the plunger and the cylinder of the pump and the motor is too large, or the clearance of the distribution plate is too large, and the clearance of the seal of the hydraulic cylinder causes the clearance to be too large, and the gear end face of the pilot gear pump and Excessive tooth gap can cause serious endoleaks. When the oil leaks, its pressure energy will be converted into heat energy, causing the temperature of the hydraulic oil to rise, resulting in high temperature in the hydraulic system.

 

If the pressure adjustment of the hydraulic system pump, relief valve and safety valve is unreasonable, the hydraulic system temperature will be too high. If the system pressure is adjusted too high, the pump will run above the rated pressure, causing the oil temperature to rise. If the system pressure is adjusted too low, the working mechanism will under normal load, and the overflow valve will be opened and unloaded frequently, so that most of the hydraulic oil will flow back to the tank through the safety valve. This will increase the power of the hydraulic system and cause the hydraulic system to overflow.

 

If the pilot relief valve pressure is too low, the excavator reversing valve stem reversing block, resulting in slow movement, and easy to cause high temperature of the hydraulic oil, so according to the different load requirements of the excavator, often check and adjust the pressure of the safety valve , to make it reach the set value.

 

Is the hydraulic oil suitable?

 

The unreasonable selection of hydraulic oil type can also cause high temperature, and the hydraulic fluid with suitable viscosity can reduce friction loss. In the summer, a slightly higher viscosity hydraulic oil should be selected to reduce internal leakage. In the winter, hydraulic oil with a slightly lower viscosity should be used to reduce the pressure loss.

 

Different brands of hydraulic oil, different types of hydraulic oil of the same brand, different base oils and additives, do not have compatibility. After the hydraulic oil is mixed, the additive will react, causing the additive to fail, generating particles and foam, which will reduce the working efficiency of the hydraulic components such as pumps, motors and valves, and increase the wear.

 

If the hydraulic oil is not clean, the hydraulic system will be blocked, resulting in an increase in the frictional resistance of the hydraulic system. This not only causes an increase in failure, shortens the life of the component, but also causes the temperature of the hydraulic system to rise. Poor quality hydraulic fluid can cause air to mix in the hydraulic system. The air escapes from the oil to form bubbles, which can cause local high temperatures and damage the hydraulic system when the bubbles are cracked.

 

If the oil level in the hydraulic tank is too low, the hydraulic system will not have enough oil flow to take away the heat generated by it, resulting in difficulty in heat dissipation and an increase in oil temperature. If the oil in the tank is insufficient, it should be added to the standard level in time.

 

Is the driver's operation improper?

 

If the driver manipulates the excavator to move too hard and the motion is inconsistent, the hydraulic system temperature will be too high. In the hydraulic system, the oil circuit and components work under high pressure for a long time. In addition to the power loss of the pump, motor, relief valve and pipeline system, the power loss of the balance valve, the buffer valve and the single throttle valve are also large, which will also cause Hydraulic oil is hot.

 

Therefore, when the excavator is working under heavy load, the main relief valve and the safety valve should be avoided as much as possible. When excavating, try to do more compound action and less single action.

 

It can be seen from the above analysis that the cause of excessive oil temperature is various. It is important to control the hydraulic system hydraulic fluid temperature within the normal range. The driver should pay attention to the correct use and maintenance of the excavator. When the temperature of the hydraulic oil is too high, the fault should be checked and eliminated in time to ensure the normal and stable operation of the excavator.