How to deal with hydraulic system leaks

Hydraulic transmission system has the advantages of small size, light weight, large specific power, smooth operation, stepless speed regulation, etc., in a variety of cranes are widely used. However, the transmission efficiency of the hydraulic transmission system is lower than other transmission systems, easy to produce faults and failure analysis and troubleshooting is more difficult. Therefore, the use of maintenance personnel are required to have a certain degree of basic knowledge of the hydraulic system.

Classification of leakage

Construction machinery hydraulic system leakage there are two main types of leakage, fixed seal leakage and movement seal leakage, fixed seal leakage of the parts mainly include the bottom of the cylinder, the connection of the pipe joints, etc., the movement seal mainly includes the cylinder piston rod parts, multi-way valve stem and other parts. Leakage from the fluid can also be divided into external leakage and internal leakage, external leakage mainly refers to the hydraulic oil leakage from the system to the environment, internal leakage refers to the existence of high and low pressure side of the pressure difference and seal failure and other reasons, so that the hydraulic oil in the system by the high-pressure side of the low-pressure side of the flow.

Manufacturing and assembly factors

(1) Manufacturing factors

All hydraulic components and sealing components have strict dimensional tolerances, surface treatment, surface finish and form tolerance requirements. If the manufacturing process is poor, for example: the piston radius of the cylinder, sealing groove depth or width, loaded with sealing ring hole size is poor or due to processing problems caused by out of round, itself has a burr or puddle, chrome plating off, etc., the seals will be deformed, scratched, pressed or pressed phenomena such as the phenomenon occurs so that it loses sealing function.

(2) assembly factors

Hydraulic components in the assembly should put an end to barbaric operations, if excessive force will make the parts deformed, especially with copper rods and other knocking cylinder, sealing flange, etc.; assembly should be carefully examined before the parts, assembly should be dipped in a small amount of hydraulic oil, gently pressed into the cleaning application of diesel fuel, especially seals, dust rings, O-rings, and other rubber components, if gasoline is easy to aging loss of the original elasticity, and therefore Loss of sealing function.

Reasons affecting leakage

(1) Seal selection

The reliability of the hydraulic system, to a large extent, depends on the design of the hydraulic system seal and the choice of seals, due to the design of the sealing structure selection is unreasonable, the choice of seals is not in line with the norms, in the design does not take into account the hydraulic oil and sealing material compatibility type, load conditions, limit pressure, working speed size, ambient temperature changes, and so on. These are in different degrees directly or indirectly cause the hydraulic system leakage. In addition, due to the use of construction machinery in the environment with dust and impurities, so in the design to choose the appropriate dust seal, to avoid dust and other dirt into the system to destroy the seal, contaminate the fluid, thereby generating leaks.

(2) Other design reasons

Considering the geometric accuracy and roughness of the moving surface in the design is not comprehensive enough as well as not carrying out the strength check of the connection parts in the design, etc., which will cause leakage in the work of the machinery.

Oil contamination and damage to parts

(1) gas pollution

At atmospheric pressure, the hydraulic oil can dissolve about 10% of the air, in the hydraulic system under high pressure, in the fluid will dissolve more air or gas. Air in the oil to form bubbles, if the hydraulic support in the working process in a very short period of time, the pressure in the high and low pressure between the rapid change will make the bubble in the high-pressure side of the high temperature in the low-pressure side of the burst, if the surface of the components of the hydraulic system has a concave point and damage, the hydraulic oil will be high-speed rushing to the surface of the component surface to accelerate the surface wear and tear, resulting in leakage.

(2) particle pollution

Hydraulic cylinder as some construction machinery hydraulic system of the main executive element, due to the working process of the piston rod exposed directly in contact with the environment, although the guide sleeve is equipped with dust rings and seals, but it is inevitable that dust, dirt into the hydraulic system to accelerate the seals and piston rod and other scratches and abrasion, resulting in leakage, particle contamination for the fastest damage to the hydraulic components of one of the factors.

(3) parts damage

Seals are made of oil-resistant rubber and other materials, due to prolonged use of aging, cracking, damage, etc. will cause system leakage. If the parts in the work process by collision and damage, will scratch the sealing element, thus causing leakage.