Quote:
Originally Posted by Chris is me
The ratings are for a maximum recommended load over a long life, not ultimate tensile strength, so the belts aren't going to snap the instant your robot tips on two wheels.
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Agreed, the ratings are for 3,000 hours of use, where an frc bot would see 10-20 conservatively.
What about the 10th, 100th, or 1,000th time it rocks? The point is there is a lot of advice in this thread, it could be very helpful or not so helpful. Most of it is not fully quantified. Yes, increasing wheel diameter increases load on the belts. Yes, increasing pulley diameter decreases load on the belt. Yes, increasing belt width increases srength. Yes, increasing tooth engagement helps with power transmission. It's basic physics, but what is the design point? How much load is the difference between a belt breaking or lasting? What tooth engagement is necessary? Taking a look at the numbers can be very helpful in understand the failure modes.
Quote:
Originally Posted by Chris is me
Dozens of teams have run 15mm wide belts on 24T and larger pulleys and 9mm wide belts on even larger pulleys. These aren't about to snap. 9mm belts on 24T pulleys are pushing it. Smaller pulleys can lead to failure in a drivetrain. Load ratings are conservative and for use cases that aren't like FRC - using them as gospel here isn't necessary, and it isn't a poor decision to go with what's worked for many teams for several seasons, really. We push the rated limits of 25 chain all the time too.
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Define pushing it, what does that correlate to? When does it become an acceptable FRC design and the requirements it is held to?
How do you quantify a 24t pulley 15mm setup: What size wheels? What power input from the gearbox? That can be very helpful information to say we loaded our belts to X pounds and didn't see a a failure.