1.Hydraulic shock caused by sudden closing of valve
When the hydraulic valve is opened, the liquid flow in the pipe. When the valve is suddenly closed, start the rapid conversion of the kinetic energy of liquid into pressure energy from the valve, resulting in a high pressure shock wave from the valve to the chamber; since then, the cavity began to convert the pressure of liquid into kinetic energy, liquid reverse flow; then, the liquid kinetic energy is transformed into pressure energy and a high pressure shock wave is formed, so the energy conversion is repeated, and the pressure oscillation is formed in the pipeline. Because of the influence of the internal friction and the elastic deformation of the pipe, the oscillation process will gradually decline and become stable.

2.Hydraulic impact caused by sudden braking or reversing of moving parts
The hydraulics directional control valve closes the oil return passage of the hydraulic cylinder and the moving part is braked, the kinetic energy of the moving part in the moment can be transformed into the pressure energy to closed the oil, and the pressure is increased rapidly, forming the hydraulic impact.

3.Hydraulic shock caused by malfunction or insensitivity of some hydraulic components
When the hydraulic system relief valve in the system to do the use of safety valve, if the system overload while the safety valve can not be opened in time or simply can not open, it will lead to a sharp increase of the pressure of the pipeline system, lead to hydraulic impact.

DMG-02-70 hydraulics directional control valves,DMG-02