Quote:
Originally Posted by DampRobot
There's no problem using 9mm pulleys in the drive, given you do the math, and take a look at what worked in the past. 971 ran 9mm, 24 (or so) GT2 pulleys with 3.5" diameter, 2" wide wheels and a traction limited low gear. As far as I know, they never had any issues ratcheting. There are plenty of other threads discussing this, but the horsepower ratings Gates gives are conservative for FRC applications.
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According to the Google Doc that Adam Heard compiled, they had minor ratcheting issues.
If you use a LARGE pulley you can get away with 9mm, but there is very little penalty to stepping up to 15, and you will most certainly never ratchet if properly configured. Our design mandates smaller pulleys, so it's safer for us to go 15. Anyone with the guts (or foolishness
) to do a belt-in-tube system should probably go 15mm.
If you go 9mm, use GT / GT2 pulleys. HTD won't cut it.