The chain used for material handling is similar to the chain used for chain drive. The most common conveyor chain in engineering is the roller chain.
        The so-called double plus conveyor chain is a kind of roller conveyor chain. On the conveyor line, the moving speed of the chain remains unchanged, but the tooling plates and workpieces conveyed above the chain can be controlled according to the user's requirements. The tempo stops the movement at the position where it is required to be stopped, and the operator performs various assembly operations to complete the above operation and then continue to move the workpiece forward. Therefore, the double speed conveyor chain can also be called a beat conveyor chain, a free-beat conveyor chain, a double speed chain, a differential chain, and a differential chain.