Couplings have double-end tooth profile, single-end tooth profile, jaw type, leaf spring type, disc spring, cross slide type and roller chain type. Because of the different types, some are lubricated with lubricating oil, and some are lubricated with grease. The main coupling of the steel mill rolling mill refers to the cross slide universal coupling, which is an indispensable part of the steel rolling equipment, and the working conditions are extremely harsh. The semicircular connecting copper slider will work under severe impact load and extreme pressure (the deflection angle of the connecting rod is often greater than 120). Therefore, the plane and arc surface of the slider will be severely worn. In addition, the entire coupling is also exposed to dust, scales, moisture and high temperature. Obviously, under such harsh working conditions, maintaining good lubrication is very important. The lubricating greases for the main coupling slider of the rolling mill mainly include extreme pressure lithium grease (including semi-fluid extreme pressure grease), graphite calcium grease and calender grease. Where there are special requirements, suitable special grease should be used first. In the main shaft coupling of the tandem rolling mill, the sliding type and the gear type are generally used, which have commonality in lubrication, and use lithium-based grease or. MOS, as the main anti-friction agent, can obtain the effect of reducing friction. At the same time, in order to improve the adhesion, pressure feedability, Timken test OK value of the coupling grease, reduce the amount of friction iron powder, and improve workability and extend the life of the gear, special calcium-based grease can also be used.