Quote:
Originally Posted by cbale2000
What lubricant were you using and what was the overall reductions in your drive system (including wheel size)?
IMO our 2014 robot put it's 3 CIM Ball shifters through far more abuse than the average team and the gears still look as good as new. For that matter, I've yet to see so much as a chipped tooth on any of the over 75 various Vex Pro gears we've used on competition robots in the past two years.
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Gear ratios were 18.75:1 and 7.08:1. Gearboxes were lubricated with moly grease containing Teflon. The gearbox direct drove a 6" x 2" wheel at the center of the robot which was chained to the other two wheel in the drive train side, also 6" x 2" wheels. All wheels were treaded with blue nitrile. Center direct drive shaft was supported with a bearing in the outer plate. Two other axles were dead shafts with bearings in the wheel.
The high load situation I believe created the problem was encountered when the driver returned the control stick to a neutral position with the robot at a high speed. The auto shifting code would have immediately tried to shift the robot to low gear with all three cim motors braking.
I've spent a fair amount of time "behind the glass" as it were. I'd challenge you to find a driver who pushed their robot harder and drove more aggressively.
I truly believe that we saw this failure because we pushed the design to its performance limit and shaft deflection leading to angular gear misalignment and ultimately gear tooth failure was the manifestion of that failure. If it had been on only one drive train side or it only happened one time I would write it off as bad luck, but that was not the case.