Roller chain coupling is characterised by simple structure (consisting of four pieces), easy assembly and disassembly, no need to move the two shafts being coupled when disassembled, compact size, light weight, compensating ability, low requirements for installation accuracy, work, longer life, lower cost and other advantages.It can be applied to the shaft transmission of textile, agricultural machinery, lifting and transporting, engineering, mining, light industry, chemical industry, etc. It is suitable for high temperature, humid and dusty working conditions, not suitable for high speed, violent impact load and axial force transmission occasions, and should be worked under the condition of good lubrication and protective cover.The load bearing capacity depends on the pressure of chain roller and sprocket teeth and the shear strength of chain pin.However, if the centrifugal force is too large, it will accelerate the wear and heat of the components, so it should not be used in the transmission of high speed, and due to the cushioning and vibration-absorbing ability, it should not be used in the frequent start-up and under the work of strong impact.The permissible relative radial displacement of the two shafts is as follows: when double-row chain is used, △y=0.02p (p is the pitch of the chain); when single-row is used, △y is 0.05~1.2mm; the permissible relative angular displacement △a is not more than 1°.The material of half coupling is often 45, ZG45 or 20Cr steel, and is carburised and surface quenched to HRC=40~45. The cover is often aluminium alloy casting.