Full definition
The precise positioning of all pulleys in a belt drive system so their grooves are coplanar, ensuring the belt enters and exits each groove without lateral force. Misalignment types: angular (pulleys tilted relative to each other) and parallel offset (shaft axes parallel but not coplanar). Maximum tolerances: 0.5° angular and 0.5 mm offset per 100 mm of center distance. Misalignment causes uneven belt wear on one sidewall, noise, vibration, reduced efficiency, and premature belt failure — it is the second leading cause of belt drive problems after improper tension. Check with a straightedge, string line, or laser alignment tool (SKF TKBA, Gates laser). Per ISO 1081 recommendations. Correct both angular and offset before tensioning.