The gap between the cylinder barrel and the piston in the hydraulic cylinder is mainly determined by the size of the cylinder and the seals used in the standard spacing. These two are used to choose. The use of the cylinder, in general, there are four main types, is the boom on the elastic cylinder and luffing cylinder, as well as the leg on the elastic cylinder and straight cylinder. Among them, the boom elastic oil cylinder is used to adjust the boom length, and the boom luffing oil cylinder is used to adjust the boom elevation angle.