There are many ways to install the centering idler group, such as four-bar linkage type, vertical roller mill and intermediate shaft type. The principle is that the belt can be automatically centripetally adjusted by blocking or idler rotating in the horizontal plane to block or generate transverse thrust, and the stress condition is the same as that of the bearing idler group.The adjustment method of tail roller is just opposite to that of head roller. The specific method is which side of the belt, which side of the idler group moves forward towards the belt, or the other side moves backward.In general, this method is more suitable for the vertical roller mill with bidirectional operation state or the total length of the vertical roller mill is short. This is mainly because the shorter vertical roller mill is more prone to run off and is not easy to adjust compared with the longer belt conveyor, If the long vertical roller mill adopts this rule, it will affect the service life of the belt.