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Unread 17-11-2015, 12:56
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Re: Possible to extend output shaft on WCP Gearbox?

Quote:
Originally Posted by InFlight View Post
Use of small pulleys really decreases the torque rating of these belt drives. Compared to a 36T pulley a 24T is about a 53% reduction in capability, while a 22T is down to ~47%.

A 15 mm wide belt is 40% stronger than a 9 mm belt. The extra strength may help some, but it is still poor compensation for a bad design.
How is going to a 40% stronger belt "compensation for a bad design", but going to a 47% stronger pulley size the proper decision? They seem to both fix the problem about the same, it's just horizontal space versus vertical space which is design dependent.

I've built several belt drives - 15mm wide belts and 24T pulleys on a WCD with 4-6" wheels have been completely issue free for us. 9mm/24T has not treated us as well. I don't see this as a bad design decision to use wider belts when we don't have the clearance for bigger pulleys.

Definitely look at the formulas and understand the rating for each belt - and then also remember that the resources specified by the manufacturer are generally for machines with 20x the run time of the average FRC robot, so you can go a bit closer on the safety margin than you might expect.
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