The hydraulic transmission system has the advantages of small size, light weight, large specific power, stable operation, stepless speed regulation, etc., and is widely used in various cranes. However, the transmission efficiency of the hydraulic transmission system is lower than that of other transmission systems, which is prone to failure and the analysis and elimination of the failure is difficult. Therefore, the maintenance personnel are required to have a certain basic knowledge of the hydraulic system.

There are two main types of leakage in the hydraulic system of construction machinery. Leakage at the fixed seal and leakage at the movement seal. The leak at the fixed seal mainly includes the bottom of the cylinder and the joint of each joint. The movement seal mainly includes the piston rod of the cylinder. Multi-way valve stem and other parts. From the leakage of oil, it can also be divided into external leakage and internal leakage. The external leakage mainly refers to the leakage of hydraulic oil from the system to the environment. The internal leakage refers to the existence of the pressure difference between the high and low pressure sides and the failure of the seal. Hydraulic oil flows from the high pressure side to the low pressure inside the system


All hydraulic components and sealing components have strict dimensional tolerances, surface finishes, surface finishes and dimensional tolerances. If the manufacturing process is out of tolerance, for example: the piston radius of the cylinder, the depth or width of the sealing groove, the hole size of the sealing ring is too poor, or the machining is caused by the problem of rounding, burrs or burrs, chrome peeling, etc. The piece will be deformed, scratched, crushed, or pinched, causing it to lose its sealing function.

Ningbo reducer_Winding winch_Rotary reducer_Hydraulic transmission_Planet reducer|Ningbo Donghu Hydraulic Transmission Co., Ltd.

Hydraulic components should be eliminated from rough operation during assembly. If excessive force is applied, the parts will be deformed, especially with copper rods, etc.; the parts should be carefully inspected before assembly, and the parts should be slightly hydraulic when assembled. Oil, gently press in, apply diesel oil during cleaning, especially rubber components such as seal ring, dust ring, O-ring, etc. If you use gasoline, it will easily age and lose its original elasticity, thus losing the sealing function. The reliability of the hydraulic system depends to a large extent on the design of the hydraulic system seal and the choice of seals. Due to the unreasonable selection of the seal structure in the design, the selection of the seal is not in accordance with the specifications, and the hydraulic oil is not considered in the design. The compatibility type of the sealing material, the load condition, the ultimate pressure, the working speed, the change of the ambient temperature, and the like. These all directly or indirectly cause hydraulic system leakage to varying degrees. In addition, due to the dust and impurities in the working environment of the construction machinery, it is necessary to select a suitable dustproof seal in the design to prevent dust and other pollutants from entering the system to damage the seal and contaminate the oil, thereby causing leakage. The design considers that the geometrical accuracy and roughness of the moving surface are not comprehensive enough, and there is no strength check of the joints in the design, which will cause leakage in the mechanical work.

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 is dissolved in the oil. Air forms bubbles in the oil. If the hydraulic support changes rapidly between high and low pressure in the short time during operation, the air bubbles will generate high temperature on the high pressure side and burst on the low pressure side if the components of the hydraulic system When there are pits and damage on the surface, the hydraulic oil will rush toward the surface of the component to accelerate the wear of the surface, causing leakage. As the main actuator of some engineering machinery hydraulic system, the hydraulic cylinder is directly exposed to the environment during the working process. Although the dustproof ring and the seal are installed on the guide sleeve, dust and dirt are inevitable. Into the hydraulic system, accelerate the scratches and wear of seals and piston rods, causing leakage, and particle contamination is one of the fastest factors for hydraulic component damage.

The seal is made of oil-resistant rubber and other materials, which may cause system leakage due to aging, cracking, damage, etc. due to prolonged use. If the part is damaged by a collision during work, it will scratch the sealing element and cause a leak.