The hydraulic valve core, valve sleeve, valve body and other mechanical parts have friction between the movement pairs during use, which makes the size, shape and surface quality of the parts change and fail. These may make the valve fail.
Working under long-term variable load, the spring in the hydraulic valve will become soft due to fatigue, shorten the length of the spring, or break completely; the valve core and valve seat will also be cracked, peeled or damaged due to fatigue. The spool of the reversing valve is bent and deformed, which will make it difficult for the reversing action of the valve to proceed normally. The relief valve pilot cone valve (or pilot small ball valve) is not tightly sealed due to wear and cannot be adjusted normally. The wear of the pilot valve of the pressure reducing valve will make the valve work unstable and even unable to regulate the pressure. Fatigue or broken springs on the main slide valve or pilot valve of the relief valve will make the system pressure less than required. If the matching clearance between the valve core and the valve hole is too large, pressure shock will occur. The spool of the overflow valve is bent and deformed or the spring is deformed, which will make the spool move inflexible and cause the system pressure to be unstable.
When the residual stress of hydraulic valve parts during processing and the external load stress during use exceed the yield strength of the material of the parts, the parts will deform and fail to complete their normal functions. If the spring of the reversing valve of the Hydraulic Press is too soft or short, it will affect the spool working position and normal reset, making the system unable to work normally. Note that improper assembly may also cause deformation of the parts. For example, the valve body deformation caused by the reversing valve assembly screw is tightened too tightly, which may cause the valve core to jam.
Excessive water or acidic substances mixed in hydraulic oil will corrode the relevant parts in the hydraulic valve after long-term use, causing it to lose its due accuracy and become invalid. The abrasion or deformation of the valve core of the electromagnetic reversing valve will cause the valve to leak and reduce the efficiency, and the dirt will easily enter the gap or deformation, so that the valve core will be blocked by the gas. The bending and deformation of the spool of the unloading valve will slow down the action of the spool, and make the conversion process of the system from unloading to working pressure or working pressure to unloading slow. The one-way valve of the one-way throttle (speed control) valve is partially worn and the seal is not tight. Part of the oil flow will flow away through the one-way valve, which affects the sensitivity of the speed control.