European truck solenoid valve is a coil wrapped into a tightly packed spiral line. Solenoid valve generally circulation coefficient is very small, and the working pressure difference is very small. For example, the general 25 caliber solenoid valve circulation coefficient is much smaller than the 15 caliber electric ball valve. The solenoid valve is driven through the solenoid coil, which is relatively easy to be damaged by the voltage impact. Equivalent to the role of the switch, is on and off two functions. Electric valve drive is generally with a motor, more resistant to voltage impact. Solenoid valve is fast open and fast close, generally used in small flow and small pressure, the requirements of the switching frequency of the electric valve. The opening degree of the electric valve valve can be controlled, the state is open, off, half open and half off, can control the flow of the medium in the pipeline and the solenoid valve can not meet this requirement.