Teach you to solve the leakage problem of the loader hydraulic system（1）

Teach you to solve the leakage problem of the loader hydraulic system

Loaders are mainly used for shoveling, loading, unloading, and transporting bulk materials such as soil and sand, as well as light shoveling operations on rocks and hard soils. Because it has the advantages of fast operation speed, high efficiency, and light operation, it has become one of the widely used earth and stone construction machinery. According to statistics, hydraulic system failures occupy the first place in the proportion of failures in various systems of loaders. What are the causes of hydraulic system leakage? How to solve it?

Classification of hydraulic system leakage

 

The leakage of the hydraulic system of the loader is mainly caused by the pressure difference generated when the liquid flows in the hydraulic components and pipelines and the gaps between the components. There are two main types of oil drain in the hydraulic system of a loader. One is the static joint surface (ie, the fixed part, mainly including the joint between the cylinder head and the cylinder, the joint of each pipe joint, etc.) of the sealed oil; the second is the dynamic joint. The joint surface (that is, the sliding part, which mainly includes the multi-way valve stem, the cylinder piston and the inner wall of the cylinder, the piston rod and the cylinder head guide sleeve, etc.) seals and drains the oil. The specific manifestations are external leakage and internal leakage. The external leakage oil is mainly produced on the outside of the hydraulic system, that is, the oil leaks from the various components of the hydraulic system to the external environment. Internal leakage refers to the fact that hydraulic oil flows from the high pressure side to the low pressure side in the system due to the existence of the pressure difference between the high and low pressure sides and the failure of the seals.

 

Factors causing leakage

Selection of hydraulic oil

 

In the hydraulic system, hydraulic oil is not only a medium for transmitting power, but also a lubricant and coolant. To ensure that the hydraulic system can work reliably, efficiently and economically under various conditions, the hydraulic oil must have a suitable viscosity and good viscosity-temperature characteristics. Viscosity is an important indicator of hydraulic oil. For a certain hydraulic system, only working media with a limited range of viscosity can work normally. If the viscosity is too large, the resistance increases when the oil flows, the temperature rises quickly, the energy loss is large, and the system efficiency is reduced; if the viscosity is too small, the volume loss of the pump is increased, and the oil film supporting ability is reduced, which leads to dry friction between the moving pairs, causing Increased leakage.

 

Oil contamination

 

Gas pollution：

At atmospheric pressure, about 10% of the air can be dissolved in the hydraulic oil. Under the high pressure of the hydraulic system, more air or gas will be dissolved in the oil. Air forms bubbles in the oil. If the hydraulic system is working in a very short period of time, the pressure changes rapidly between high and low pressures, which will cause the bubbles to generate high temperatures on the high pressure side and burst on the low pressure side. When there are pits and damages on the surface of the element, the hydraulic oil will rush to the surface of the element at high speed to accelerate the surface wear and cause leakage.

 

Water pollution：

Due to the humidity of the working environment and other factors, it may cause external water to enter the hydraulic system. The water will react with the hydraulic oil to form acidic substances and sludge, reducing the lubricating performance of the hydraulic oil, accelerating the wear of the components, and the water will also cause the control valve. The valve stem is rusted, making the control valve difficult to operate and scratching the seals, causing leakage.

 

Solid particle pollution：

The hydraulic cylinder is the main executive element of the hydraulic system of the loader. Because the piston rod is exposed and directly contacts the environment during the working process, although the guide sleeve is equipped with dust-proof rings and seals, it is inevitable that dirt will be brought into the hydraulic system. , Accelerate the scratches and wear of seals and piston rods, causing leakage

 

Part reason：

 

1. The joint surface of hydraulic components is damaged during assembly and maintenance, or the paper pad is damaged by pressure oil, or there is flatness error on the joint surface during the repair process, or the joint screw is not tightened, etc., may cause joint surface leakage; if rough operation, Excessive force, especially hitting the cylinder block and sealing flange with copper rods, etc. will deform the parts and cause leakage.

2. The seal is made of oil-resistant rubber and other materials. The aging, cracking, damage, etc. due to long-term use will cause system leakage. If the parts are damaged by collisions during work, the sealing elements will be scratched, causing leakage. Or the system pressure is too high, causing the seal to fail and cause leakage.

3. The increase of the spool valve clearance in the hydraulic control valve leads to an increase in leakage.