Originally Posted by
sploo
Having run a few more numbers from the Optibelt catalog it looks as though I might have a problem with the proposed design. The 25mm AT5 belt itself is fine, but a 20 tooth to 60 tooth combination appears to have insufficient tooth engagement to carry the torque.
I don't completely understand the metric, but the belts have a W/mm rating based on the small pulley rpm (where the figure is higher for higher rpm figures). I'm guessing this is torque related (as the same wattage at a higher rpm requires less torque, vs that wattage at a lower rpm).
The doc suggests I should probably consider my power requirement to be around 0.126kW, but the above configuration has a nominal power capacity of just under 0.1kW.
Moving to a 30 tooth pulley for the smaller side results in more tooth engagement, and a nominal power capacity of 0.25kW (so well above 0.126kW). That obviously only gives 2:1 reduction, and there doesn't appear to be an AT5 pulley larger than 60 tooth.
I could use a 20 tooth small gear, but the figures suggest I'd need a 66mm wide belt! Further thinking required...