#25 Chain

[Steven Smith]

We broke a #25 pitch chain this year for the first time.

Robot is geared for ~15ft/s, 8" pneumatic wheels, ~115lbs actual weight. We were coming over a defense dukes of hazard style and the driver slammed it in full reverse as the front wheels were landing and point loaded them, causing the break.

All of our chains were run chain in tube with dual bearing supports, however there was an issue found in the post mortem where aan additional 1/16th spacer got added, which caused 1/16th misalignment on an 8" CtC run.

Bot #2 (comp) was made with #35 pitch chain as an insurance policy since we had the weight allowance. We fixed bot #1 and left the #25 pitch on it. After a week zero event and ~5-10 additional hours of driver practice under extremely heavy defense, we haven't broken another #25pitch.

tl;dr - Make sure your sprockets are well support and well aligned and you shouldn't have an issue with #25 even in the most abusive drivetrain conditions. Want some extra insurance, run #35, but it still isn't an excuse to not pay attention to alignment and tension. It always pays to do the math though and compare it to the ultimate strength of your chain for edge cases.