It is commonly referred to as: self-flow conveying system. Double speed chain conveyor is mainly used for material transportation in assembly and processing production lines. Its conveying principle is to use the speed increasing function of double speed chain to make the tooling board supporting the goods run fast. The blocker stops at the corresponding operation position; or the accumulation instruction and the functions of shifting, indexing, and dedicated line are completed by corresponding instructions. Since the plate for transporting the goods needs to be used repeatedly, it is rarely used in a single unit, but is matched with various special machines such as a jacking machine and a jacking machine to form a horizontal or vertical circulation system.