Minimum Belt Wrap and Tooth Engagement

Did you know that synchronous belts need a minimum amount of wrap along with a minimum amount of teeth in mesh to transmit rated loads?  The minimum teeth required in mesh to achieve rated drive capacity is 6 teeth.  Anything less than 6 teeth reduces rated capacity significantly.  In fact, for each tooth less than 6, you lose 20% of the rated load!  This means at 4 teeth, you’re already down 40% of the rated load capacity!  And as mentioned above, this isn’t the whole story.  Even if you have 6 teeth in mesh, but you have less than 60 degrees of wrap, you may have belt problems.  This really only applies to drives with more than two shafts.  Idlers that do not transmit load do not have a minimum tooth engagement or degree of wrap required.