How to attach axle to FisherPrice gearbox?

Hello fellow robotics people,

We were hoping you could help us figure out how to attach an axle to a FisherPrice gearbox. It would be very much appreciated. The gearbox we are speaking of can be found in the link above. Every year we get one of these in the kit of parts, and every year we are unable to figure out how to actually use them. Is there a standard method of attachment? If so, what is it?

Thanking in advance,
Team 2945

There’s a pretty good one that’s been used for a while.

If you look at the inside of the output gear, you’ll see that there’s a geometric shape. Cut a block of material to that shape, with a keyway or hex or whatever your preferred axle or other power-moving device uses, and put that in. Use setscrews and/or a hose clamp to keep it in place.

We used a hexagonal PVC piece that we bought from our local hardware store. To ensure the rod spins we carefully drilled through the PVC and the axle and put in a pin. This worked pretty well for us. I hope this picture helps:

The original hub from the Fisher Price vehicles provides an easy way to connect to the transmission output shaft. Search for either of these part numbers:
74570-2239 or 74460-2249.

Drill out this plastic hub to 1/2" and screw it to a turned down v pulley or some thing else that can be a hub with a keyway.

Prior to 2005 or 2006, these hubs were included in the KOP.

Last season we found a description of an interface here on CD and re-created it ourselves. I wish I could find the link, but no luck.
It is created by drilling a circular hole with the same diameter as the transmission output. The holes are the same diameter of each finger, or tab, on the transmission. We then drilled and tapped for a 1/2" shaft. Finally we cross drilled through the entire assembly.
We ran this through one regional, Nationals, Cal Games and MadTown and NEVER once had a single issue with it.

Our solution is shown in a photo linked above.

This looks like a pretty solid design. If I understand correctly, you drilled several holes to fit each finger of the output? Also, what material did you use for the assembly?

We actually had a “hub” manufactured to mesh with the fingers of output, but this was a considerable amount of weight, and if it can be avoided, we’re always up for new ideas.

Anyone know where we can get one of those 74460-2249 hubs?

I think you are referring to this solution:


YES! Thanks Clinton! That is exactly where we got the idea. Follow Clinton’s link for more details.

We made ours out of a scrap disk of PVC. One of our sponsors is Precision Plastics. They gave us a box of all types and sizes of scrap a couple years ago. It was just one of the items in the box. It needed a little cleaning up on the lathe but after that it was perfect.

Okay awesome. Yeah in that case I’d wanna try PVC lumber, bascially a lightweight yet strong material my team has used for a number of years now with a ton of success. You can get 1x4 lengths of it at Lowes.