In order to implement the coupling foundation, the universal standard chain coupling uses a common chain and meshes with two side-by-side sprockets with the same number of teeth. The main difference between chain couplings of different structure types is the use of different chains, and the common ones are double rows. Roller chain couplings, single-row roller chain couplings, toothed chain couplings, nylon chain couplings, etc. The chain coupling has a simple structure (composed of four pieces), easy assembly and disassembly, no need to move the connected two shafts during disassembly, compact size, light weight, certain compensation capability, low installation accuracy, reliable work, and longevity The advantages of longer length and lower cost are widely used in various important structural parts in quenching and tempering treatment, especially those connecting rods, bolts, gears and shafts that work under alternating loads.