pic: New gearbox

The kids Almost finished putting the new gearbox together tonight.

I had cut the plates on the laser at my work s few days ago, I didn’t realize they made it so the pinion in the one cim is driving both the gears

The double loading on the left CIM pinion is definitely a concern.

However, what makes me wonder “Why?” is all the extra space between the gears and the near plate. Not that I think this is a good idea, but it looks like there’s enough space to move the gear on the right shaft away from the left pinion and still have room for a chain or belt to transfer torque to the center shaft. So, what’s with all that space?

Hmm… would it alleviate some of the load on that middle pinion if you slid the gear connecting the pinions towards the motors? The pinion would still be carrying the torque of both CIMs, but the wear might be distributed more evenly.

Not to me, really. 2815/1398 used a similar arrangement in 2010 to add their third motor (a Fisher-Price motor in an AM Planetary) to the guts of an AM Shifter because we had more forward-aft space than top-to-bottom space. While those robots were a pain in the butt from beginning to end, that particular part was trouble-free in five events across two robots even with hard defense and the occasional beating and banging over the bumps.

I’ve heard that 254 has had problems doing this with bending CIM shafts, but I’ve also heard that plenty of teams do it without problems. I guess it really comes down to how important that form factor is versus how bulletproof you need the gearbox to be.

I can’t quote how many or which ones of 343’s robots have done this, but I know there are multiple from 2011 and before when we used to build our own transmissions and that is never a problem I have heard about. 343 used to focus on being a bit of a defensive bully so I am sure some of those drives took quite a bit of abuse. That said, I do see the potential for the issue you mention.

It’s a long story that I’ll explain later when I get home tonight

I shiver with antici

Basically, the gearbox was designed to only use one plate and mount directly to a 21, with just a small gap between the gears and the 21, but then we just decided to put it together like this, and after I realized how the pinion is loaded like that the kids are redesigning it, and I’m gonna cut some new plates whenever they get done.

Thanks, that makes more sense.

The size of that pinion should make a considerable difference in its ability to be double loaded because the bore is constant, and the annular thickness and strength of the gear (especially at the key) increases quickly with the number of teeth (for the same tooth profile and metal grade).