Sometimes, only one V-belt fails on a drive that uses multiple V-belts. So, should all of the belts be replaced if only one of them fails, or can just the failed belt be replaced?
The answer is that all V-belts on a multi-groove drive should be replaced at the same time and with belts from a single manufacturer. Mixing new and old belts or belts from different manufacturers will create a situation where the belts do not evenly share the load. This can lead to premature belt failure and uneven wear of the sheave grooves.