[ZZII 527]

Thanks for the warnings everyone. We have an FP motor with 42mm, 256:1 BB gearbox installed on our arm and an additional 7.2:1 chain reduction. So far, there have been no problems, but we are definitely going to look at the internals tomorrow.

I think many people have said it already: impulsive loading is the killer. One thing I can think of that might make a big difference: chain backlash. If on a direction reversal, your mechanism has significant momentum before the chain engages, the stresses will be enormous. Preloading your mechanism so that the chain is always in tension is always a good idea, but in light of the new gearbox info I think it will be even more important.