Why does the hydraulic system of agricultural machinery heat up?

 

The heating of the oil in the hydraulic system will cause agricultural machinery failures such as inflexible operation, discontinuous operation, and reduced working pressure. Today, we will analyze the causes of heating of the hydraulic system and the hazards and preventive measures.

 

1. What’s the cause of oil heating?

 

(1) The fuel tank volume is too small, so the heat dissipation area is not enough. The agricultural machinery is not equipped with an oil cooling device, or although it has a cooling device, its capacity is too small.

 

(2) The unloading circuit in the hydrostatic drive systems fails or the unloading circuit is not set. The oil pump cannot be unloaded when it stops working. The entire flow of the pump overflows under high pressure, resulting in overflow loss and heating of the oil.

 

(3) The hydraulic power transmission system pipeline is too thin and too long, so the local pressure loss is large.

 

(4) Choose improper oil viscosity. If the viscosity is too large, the viscosity resistance will be large, and if the viscosity is too small, the leakage will increase. Both cases can cause the oil to heat up.

 

(5) The components of the hydraulic mechanical transmission system have insufficient precision and poor assembly quality, and the mechanical friction loss between relative movements is large.

 

(6) The fit gap of the mating parts is too small, or the gap is too large after wear. The internal and external leakage will cause large volume loss. For example, it will reduce the volumetric efficiency of the pump and make the system heat up faster.

 

(7) The working pressure of the hydrostatic drive transmission system is adjusted to be higher than actual needs. Although sometimes it is because the seal is too tight, or the seal is damaged, and the leakage has increased, and the pressure has to be increased to work.

 

(8) The high temperature climate and working environment cause the oil temperature to rise.

 

 

2. What are the risks of the excessive oil temperature?

 

(1) Too high temperature will cause thermal deformation of the machine and affect the transmission accuracy of the hydraulic power transmission system.

 

(2) It reduces the viscosity of the oil, increases the leakage, and reduces the volumetric efficiency of the pump and the efficiency of the entire system significantly. As the viscosity of the oil decreases, the oil film of the sliding valve and other moving parts becomes thinner and cut, and the frictional resistance increases.

 

(3) It will deform the rubber seal and reduce the sealing performance and service life.

 

(4) It will accelerate the oxidation and deterioration of oil and reduce the service life of hydraulic oil.

 

 

3. What are the prevention measures?

 

(1) According to different load requirements, frequently check and adjust the pressure of the relief valve.

 

(2) Reasonable selection of hydraulic oil, especially oil viscosity. Try to use a lower viscosity to reduce viscosity friction loss.

 

(3) Improve the lubrication conditions of moving parts to reduce friction loss, which is conducive to reducing work load and heating.

 

(4) Improve the assembly quality and accuracy of hydraulic components and hydraulic transmission system, strictly control the clearance of matching parts and improve lubrication conditions. Adopt sealing materials with low friction coefficient and improve the sealing structure. Reduce the starting force of the hydraulic cylinder as much as possible to reduce the heat generated by mechanical friction loss.

 

(5) Add necessary cooling devices.