Chain saw, also known as chain saw, is a portable saw powered by gasoline engine. It is mainly used for logging and timber making. Its working principle is to cut by the transverse movement of staggered L-shaped blades on the saw chain. Chain saws are generally divided into motorized chain saws, non motorized chain saws, etc. Chain saws are divided into gasoline saws, electric saws, pneumatic saws and hydraulic saws according to different sources of the same principle.