pic: 254/968 Transmission

That looks very clean, is it only one speed transmission though?
The entire thing’s only 1 lb, what are the sideplates made of? Looks like some kind of polycarbonate to me.

I think someone must have accidently turned down the gravity in your shop…

Wow, I would call that an engineering marvel. A 1 lb transmission… really goes to show how light you can actually get. Great job, if someone came up to me and told me they are going to make a 1lb transmission, I would ask them to sit down, drink some water, and rethink their statement. Man, this is amazing. Nice job, bravo. :slight_smile:

did you guys zero it before putting that caliper on there? or is that 1 lb including its weight? Because that would put your tranny at even less then 1 lb…

ahhh, I think your scale is broken.

We zeroed with the calipers on it. The sides are made of Delrin. It does shift. It may be a little deciving because that is the weight without the shifting piston and the scale goes in half pound increments. It is really about 1.2-1.3 pounds.

we have that same scale, and the same problem. I constantly have to remind everyone that 2.5 lbs over could be anywhere between 2.3 and 2.7 over.

Wow. I want one.

Our scale looks exactly the same but it doesn’t go in .5 incriments, but it goes in .2 incriments.

Which actually just as unhelpful as the .5

I bet two would be more useful.

If any one other than 254/968 posted this I am not sure I would believe it, any chance at getting a top view?

Sure. I’ll post one when I get home from work.

We’ll probably have a full bot picture up in a couple days. We didn’t remember to take any pictures of the comp bot before ship, and we havent yet fully assembled the practice bot.

I will be posting more pictures and details of the transmissions in a few days when I have some free time.

For reference, this gearbox is Kirk Oden and my senior project as Manufacturing Engineering students. As such, be prepared for some rather detailed analysis and explanations of chosen materials and processes as well as work study and analysis simulations of assembly and maintainence times. At the very least we plan on sharing our findings and suggestions on possible changes/improvements that people may want to make if they chose to pursue something similar.

In the next few days expect a new post in the technical discussion with many more pictures of the assembly and detailed part pictures, as well as explanations of the manufacturing processes, coatings, material selections and properties, part weights, etc.

That is neat and incredibly light. Wonderful

Sounds Awesome. You go to Cal Poly Pomona right?


That is quite amazing, but why #25 chain? We used it our rookie year and it broke almost every match we had (However mind you we were using a plywood robot and had a heavily cantileavered kit drill motor transmission, and a really bad tensioner!). Has 254 and 968 had those problems?

Nope. No problems. In the two years I’ve been on the team, we’ve never broken a chain. As long as it’s properly aligned and tensioned it should be fine.


This is just another beautifully made/designed part of your robot. While building our robot, we’re almost always limited by our machine shop, and the time spent on the machines. Do you know how much weight all the lightening holes and treepans remove? I’m trying to determine how much “time for weight” is involved in these transmissions. (I won’t even ask about all the heat treating and anodizing time!)

Also, I believe this is a single CIM gearbox, right? Have you found any lack of pushing power even when you’re in low gear? We used the Dewalt 3-speeds with a single CIM last year and found that we were still being pushed (well, rammed) around by kitbots.



Lightening the aluminum gears doesnt have nearly as big of an impact as lightening the same sized steel gears, obviously. The weight was removed because it could be. For the designed power constraints and face widths, the added material in the web was of no real benefit. For most of the gears we designed, we were able to remove more than half of the total gear weight using pockets and holes.

These gearboxes have 2 small CIM’s per side.