Sheave gauges are a great tool that surprisingly people don’t always know about. They have been around for quite a few years, and are just as useful as ever. They are small plastic cutouts that you place inside a sheave groove to see if there is enough wear that the sheave should be replaced. If more than 1/32” of wear can be seen between the gauge and the sidewall of the groove, the sheave should be replaced. Worn sheaves are a big contributor to premature belt failure.