The alignment of the sheaves and the correct tension of the belts enable the useful life of the bearings and the belts themselves to be utilized to the maximum. Misalignment causes asymmetric wear of the belt and does not allow the belts of a set to be uniformly loaded. Generally, it is not worthwhile carrying out regular checks on the alignment as this does not change during operation. On the other hand, alignment must always be carried out when belts are tensioned and whenever they are adjusted. The external faces of the sheaves must be on the same vertical plane when aligning and this is carried out by placing a straight edge as shown below. The face of the machine sheaves is taken as a reference and the straight edge is placed on it, checking contact at points C and D. The motor is then moved, keeping the 4 fixing screws only slightly loosened and adjusting screws 1,2,3 and 4 until contact at points A and B is also made.