Types And Causes Of Hydraulic System Leakage

Hydraulic loaders often work in environments such as humidity, dust, mud, low or high temperature, and strong light radiation, requiring their hydraulic systems to work reliably for a long time. If the hydraulic system leaks, it should be repaired in time.

1. Types of Hydraulic System leaks

There are two main types of leakage in the hydraulic system of the loader, one is the leakage of the seal at the fixed and immobile part (ie the static joint surface, such as the joint between the cylinder head and the cylinder of the hydraulic cylinder); the other is the sliding part (ie the dynamic joint surface, such as The leakage of the seal between the piston of the hydraulic cylinder and the inner wall of the cylinder, the piston rod and the guide sleeve of the cylinder head) can also be divided into internal leakage and external leakage. Internal leakage mainly occurs in the hydraulic valve, hydraulic pump (hydraulic motor) and the oil inside the hydraulic cylinder flowing from the high pressure chamber to the low pressure chamber; external leakage mainly occurs in the hydraulic pipeline, hydraulic valve, hydraulic cylinder and hydraulic pump (hydraulic motor) of the hydraulic system. ), i.e. leaking to the outside of the component. The specific performance is oil leakage caused by pipe joints, seals, component joint surfaces, housings and the system itself.

2. Cause of the Hydraulic System leak

Leaks in the hydraulic system are generally generated after a period of use. From the surface phenomenon, it is mostly caused by seal failure, damage, extrusion, or the sealing surface is pulled. The main reasons are: oil pollution, improper sealing surface roughness, unqualified sealing grooves, loose pipe joints, increased clearance of fittings, high oil temperature, deterioration of sealing rings or poor assembly, etc.

(1) The leakage of the pipe joint is related to the processing accuracy, tightening strength and whether the burr is removed at the joint. The main manifestations are that the type of pipe joint selected does not match the conditions of use; the structural design of the pipe joint is unreasonable; the processing quality of the pipe joint is poor and does not have a sealing effect; The joint tightening torque is too high or insufficient.

(2) The leakage caused by the seal is related to the damage or failure of the seal. The main manifestations are that the material or structure type of the seal does not match the conditions of use; the seal fails, the compression amount is insufficient, aging, damage, unqualified geometric accuracy, poor processing quality, and irregular products; the hardness, pressure resistance level, deformation of the seal Indicators such as rate and strength range are not satisfactory; improper installation of seals, worn or hardened surfaces, and expiration of life but not timely replacement.

(3) The leakage caused by the joint surface of the components is related to the design, processing and installation. The main manifestations are that the design of the seal does not meet the requirements of the specification, the size of the sealing groove is unreasonable, the sealing accuracy is low, and the matching clearance is out of tolerance; the error of the sealing surface roughness and flatness is too large, and the processing quality is poor; Deformation, so that the joint surface can not be fully contacted; if the assembly is not careful, the joint surface has dust or large plastic deformation due to damage.

(4) The leakage of the casing mainly occurs in the defects of castings and welded parts, and gradually expands under the action of pressure pulsation or shock vibration of the hydraulic system.

(5) The main reasons for the leakage of the system itself are that the system is poorly assembled and lacks vibration reduction and vibration isolation measures; the system is over pressured.