When performing a multiple belt-sheave alignment, it is imperative that all the belts and belt grooves are inspected individually for wear. If any of the belts are slipping, then all belts must be replaced at the same time. To achieve an accurate alignment between the pulleys one can use a machinist’s straightedge, or place a tightly drawn piece of string, across the faces of the sheaves to see if all four points of contact are made or you can utilize a Laser Pulley Alignment tool. Regardless of which system is used to perform the alignment, it is a good practice to monitor any changes in angularity and/or offset in the sheaves as the hold-down bolts of the machine to be moved are being tightened during the belt tensioning procedure, since this will allow the sheave alignment to be maintained true.
Alignment, Maintenance Tips by Ana Maria Delgado, CRL