Analysis of one of the causes of hydraulic valve failure: mechanical failure

The failure cause analysis of the Hydraulic Valve cannot be simply equated with the failure reason analysis of the general hydraulic valve. It cannot be simply equated with the failure cause analysis of the general mechanical parts, and it also has the factors belonging to the hydraulic components themselves.

First, analyze the causes of mechanical failure:

1, wear and tear

The movement of the mechanical parts such as the hydraulic valve core, the valve sleeve and the valve body constantly generates friction during use, which causes the dimensional shape and surface quality of the part to change and fail.

1 Electromagnetic reversing valve spool wear or deformation, will make the valve leakage, so that the efficiency is reduced, and the dirt is easy to enter the gap or deformation, so that the valve core is mechanically jammed. If the clearance between the valve core and the valve hole is too large, a pressure shock will occur.

2 The wear of the pilot valve of the pressure reducing valve will make the valve work unstable or even unable to regulate pressure.

3 The overflow valve pilot cone valve (or pilot small ball valve) is not tightly sealed due to wear and can not be properly regulated.

4 The one-way valve of the one-way throttle (speed control) valve is partially worn, the sealing is not strict, and part of the oil flow will flow away through the one-way valve, which affects the sensitivity of the speed regulation.

2, fatigue

When working under long-term variable load, the spring in the hydraulic valve will cause the spring to soften due to fatigue, the length of the spring will be shortened or the whole will be broken; the valve core and the valve seat will also be cracked, peeled off or other damage due to fatigue. These all have the potential to disable the valve.

1 The fatigue or breakage of the spring on the main spool valve or pilot valve of the relief valve will make the system pressure less than required.

2 The spring of the reversing valve is too soft or short, which will affect the working position of the spool and normal reset, so that the system can not work normally.

3, deformation

When the residual stress of the hydraulic valve parts during the machining process and the external load stress during use exceed the yield strength of the part material, the parts are deformed and fail to complete the normal function.

1 The relief valve spool is bent or deformed, which will make the spool move inflexibly, resulting in unstable system pressure. 2 The unloading valve spool bending deformation will make the spool slow, which makes the conversion process from unloading to working pressure or working pressure to unloading slow.

3 The valve spool bending deformation of the reversing valve will make the valve reversing action difficult to perform normally. Note that improper assembly may also cause deformation of the part. For example, the deformation of the valve body caused by the tightening of the reversing valve assembly screw may cause the valve body to jam.

4, corrosion

Excessive moisture or acid is mixed in the hydraulic oil. After prolonged use, it will corrode the relevant parts in the hydraulic valve, causing it to lose its proper accuracy and fail.