What are the correct procedures for aligning belts?

Published:  09 February, 2017

The answer to this month’s trouble shooter is provided by Phil Burge, country communications manager at SKF


Belt alignment or, more precisely, pulley alignment, is a principal maintenance activity. When pulleys are not aligned properly, additional loads are induced. The aim of belt alignment is to align the grooves of the drive and driven pulleys so that the belts run with minimal wear. Proper alignment extends the service life of belts and bearings, reduces vibration and noise levels, and saves energy.

Pulley misalignment can be angular, between the driving and driven pulley in either the vertical or horizontal plane, or it can be parallel, with one pulley offset from the other as the pulleys are viewed from the edge. In practice, more than one type of belt misalignment can exist at the same time. Unless belt misalignment is corrected, a new belt will last no longer than the one it replaced.

There are two ways to align pulleys: Traditional and laser. Traditional alignment methods are quick but often inaccurate. With these methods, mechanical tools such as straightedges, tape measures, wire, string, feeler gauges, spirit levels and calibrated cones are used.

In contrast with traditional belt alignment tools, laser equipment enables measurements and adjustments to be made with a very high level of precision. Belt manufacturers typically recommend a maximum horizontal angular misalignment from 1.0 to 0.25°. This accuracy can only be achieved with precision alignment tools such as laser equipment.

Laser belt alignment tools can be designed to align the faces of the pulleys, or their grooves. In general, laser systems that align the pulley grooves, provide superior accuracy to those that align the pulley faces. Aligning the pulley grooves also allows pulleys of different thickness, brand, type or face quality to be aligned accurately.

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