pic: Team 4499's off season gearbox



After hours of work, we have finally prevailed. We made all of the gears in this gearbox and is intended to be built within the drive train. It is currently geared to drive at 16 ft/min. If you have any questions feel free to ask!
EDIT: It will go 16ft/s not ft/min and this is with a 6" wheel.

16 ft/min? Did you mean 16 ft/sec? If so with what wheel size?

Wow! That’s awesome! Good luck this season, guys!

Yes, I messed that up and it is with a 6" wheel.

Very nice, this gearbox looks like a solid build. Hope to see it on a robot sometime.

Can you explain a little more about what is going on with that top shaft? Why do you have it passing through three bearings? I feel like that is inviting the potential for both misalignment and over constraint. The shaft is short enough that hopefully it wouldn’t be a real detriment, but it’s also not very useful.

It’s hard to see, but does the bottom shaft also have the same issue?

Finally, you may want to consider countersinking those exterior bolt heads in order to allow you to place your wheel slightly closer to your drive rail.

I would remove the middle bearing for the top shaft. It basically doesn’t add any support and just lowers efficiency / causes potential misalignment for no real benefit. Otherwise, seems good.

The top shaft was an interesting one to constrain. Currently, the reasoning for the middle constraint is because there is an e-clip on the other side of the bearing. This is because we are planning on mounting an encoder on the other end of the shaft. If you have any other ways to eliminate that middle support we are welcome to new ideas.

The bottom shaft is actually 2 separate shafts where one ends in the plate just before the tube and the other one starts in the plate inside the tube.

I completely agree with your last suggestion, we are working on it.

Thanks for the response!

Do I correctly understand that you are transmitting torque through an e-clip groove? If so, that’s going to be a weak spot in your drive train. Putting an e-clip between the load-bearing gears and the future encoder should be OK, and between the gears and the end bearings would not be as good as the outside, but much better than between the gears transmitting torque to/from the shaft.

Putting an E-clip between loads on a shaft is often a dangerous idea. It weakens the shaft substantially when something like a spacer could do the same job. I would just use a spacer between the two gears (that goes through where the bearing is currently located) and then put your encoder on one of the outer ends of that shaft.

I personally think 16ft/s single speed with 4-cims on 6" wheels is a bit fast. If you find that out too, are you able to increase your final reduction? VEXpro’s 82-tooth gear spacing is nice since it allows for a lot of various reductions with the gears they have in stock.

Great idea, I think I can see a few changes that we can make to the gearbox to incorporate this.

Thanks for the suggestion, we will look into implementing it.

Yes, we are able to make our own gears and change them out, we are using a 72 tooth spacing. We were just planning on making a fast drive base while learning the basics of gearbox manufacturing.