Leakage factor of hydraulic piston rod

- Sep 08, 2019-

The stability of the hydraulic cylinder directly affects the working efficiency and safety of the construction machinery and equipment, and is an important actuator in the work of engineering machinery and equipment. There is a problem with the hydraulic cylinder seal. The piston rod seal is leaking out. There may be problems with the quality of some components and cause premature leakage. Among the various hydraulic equipment manufacturers, there are also many countermeasures prepared for this, but it is obviously imperfect. Dongpu Hydraulic Seals Co., Ltd. puts forward important factors for the phenomenon of leakage (oil leakage) of a series of hydraulic piston rods that have occurred before, and advocates corresponding improvement methods for reference.


First, the external leakage phenomenon of the hydraulic piston rod seal is gradually analyzed


Most people believe that the main cause of leakage outside the hydraulic piston rod is seal failure and oil contamination. Through the disassembly of the hydraulic cylinder that was returned due to the leakage of the piston rod in the market, it was found that the sealing ring showed different degrees of wear, scratching and aging.


Is the structure of the combined seal ring used for the shaft suitable?


The main sealing structure of the piston rod is the combination of the dustproof ring and the high pressure sealing ring or the low pressure combined sealing ring. Although the imported combination y-type sealing ring is more expensive, there is basically no leakage phenomenon, and if the sealing member lip angle is designed Improper, it is easy to cause the material flow problem at the high temperature of the lip, and the size and shape of the sealing lip are changed, resulting in failure of the sealing performance.


Is there any bump on the surface of the piston rod?


A cross-sectional inspection of the piston rod seal through the hydraulic cylinder is a significant scratch. During the lifting process of the loader, the material in the bucket is slipped and hits the surface of the piston rod, causing micro-pits on the surface of the piston rod, thereby increasing the friction between the seal ring and the piston rod, and causing the seal ring to wear out.


Is there a problem with the clearance between the piston rod and the guide sleeve?


According to the design principle of the hydraulic cylinder, the fitting tolerance of the piston rod and the guide sleeve is H9/f8. However, in actual life work, due to the overloading of the construction machinery for a long time, the material expands under high temperature conditions, which easily causes the oil film on the surface of the piston rod to drop sharply, and the lubrication effect of the sealing lip is reduced. The local temperature exceeds the allowable temperature of the sealing ring, causing the sealing ring to age and lose. Sealing effect. This is also the reason why the piston rod sealing surface is black.