In the daily use of machinery, we must pay attention to observe the condition of the machine, especially the construction machinery. Most of the time, it is a minor problem that is not very noticeable. If it is not solved in time, it will become a major failure slowly. Hydraulic system failure is a phenomenon that hydraulic components or systems lose their prescribed functions, also known as failure. The ultimate failure of hydraulic system is the damage of components in hydraulic system or circuit, accompanied by oil leakage, heating, vibration, noise and other phenomena, resulting in the system can not play its normal function.
As we know that valve is a device that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries ) by opening, closing, or partially obstructing various passageways. Technically,Valves are fittings, but are usually discussed as a separate category because of the wide range of applications and quite diverse of types. When the valve stays open, fluid flows in a direction from higher pressure to the lower.