Quote:
Originally Posted by jeremylee
Hmm, we haven't had any problems at all after 2 regionals and 2 offseasons with our 2014 bot and our 3 cims ball shifters.
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Three failures on different drive train sides isn't a coincidence. We ran that drive train hard as you well know (Central Illinois 2014). It was geared aggressively and we used (honestly, inadvertently) down shift motor braking constantly because of our automatic shifting routine in our programming.
It is my belief, the reason for the failure is primarily related to the fact that the shafts that carry the final stage reduction are cantilevered. In looking at the damaged gears it was apparent the failure propagated across the gear teeth, which indicates angular misalignment. That angular misalignment also would have occurred during the periods where the gears were under the highest load.
I do believe that had that stage been steel gears they might have tolerated the abuse, but to me, the ability for the shaft to deflect and allow that angular misalignment is a design flaw. I believe there are a number of features that don't promote a rigid configuration, but the cantilever is the largest problem.
We still use the drive train as a demo robot. We chose to modify the gearbox configuration to eliminate the cantilever and we haven't see another incidence of the failure to date.