Found out why the pivot on our 2014 arm wasn't working

[s_forbes]

Originally Posted by jnicho15

It was a 2-stage VP driven by a CIM (pre-CIM Converter). This then drove the sprocket in the middle of the picture through a chain reduction which then rotated the whole arm. We had many failures during the season with this gearbox, and in this case the output stage failed.

Do you know what the reduction was for the other stage by chance?

Vexpro has a fantastic user guide for their versaplanetary gearboxes that shows what load rating you should expect the gearboxes to withstand. I bring it up every year when we're designing to show the students that there is a limit to what the gearboxes can do. It's an excellent example of "here's what the supplier says their product can handle. We have to stay in that range or it might break".

I also try to make sure that our versaplanetary assemblies have the highest reduction stages near the motor, and not the output shaft. The lower reduction stages have more meshing gears and should be able to handle higher torques, so they are the ones you want at the output of the gearbox.

By the way, I have to mention that with the beautiful carbon fiber tube and aluminum clamp construction that your team uses every year, I'm not surprised that the gearbox was the weak point. The construction of your mechanisms looks really solid!