I’m not a metallurgist, but I don’t see evidence of internal failure. That is, don’t see any evidence of cracks, internal rust, etc. Haven’t seen any other reports of this failure, and I’ve been following SC since 2006.
Given that all six bolts failed, it would seem that the issue is specific to the individual machine. It is possible that some unusual process, such as hydrogen embrittlement or galvanic corrosion could be a factor. The hubs look corroded, but there is a lot of clean grey steel showing in the bolts, and 25 lb-ft isn’t that much torque. Occam’s Razor points to overtorque.
Maybe contact Segway about this. If I were Segway, I’d want to take a close look at those bolts, in case something is occurring over time in the field. If so, maybe they’ll send you some new hubs in exchange for your failed parts.
Questions: 1. How old is the machine? 2. Why are the hubs so dirty/corroded? 3. After snapping off one or two bolts, why did you proceed with the rest of them?
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