The new set of gears are looking pretty good! Quick question - why did you choose to have a gear-driven drive instead of the conventional chains/belts? Do you feel like the added complexity/weight/inefficiency (if any) hindered your driving?
Looks shiny. I’m excited to discuss any pros and cons you experienced with this setup while at IRI in a few days. See you guys there!
Reminds me a little of our robot from 2007. While I can’t speak to the efficiency of using gears, I do know that it was by far the most powerful drive system we ever built, and to this day have yet to build a robot with chain drive that can match it.
On a different note, are those VexPro gears you’re using there?
Now, that’s a lot of gears. Shiny. But it also looks heavy. Why gears for your power transmission in lieu of a lighter approach?
Not new gears, the same gears that have run trough 4 different competitions just cleaned up and ready for more.
See you there.
Yup all VexPro
Everyone assumes that gears are heavy and inefficient but each drive half weighs less than 13 pounds including motors.
The why is simple, their bulletproof! No chains to fall off or tension, no sprockets to skip. These never failed us, even when something hard fell into the gears (see previous photos) it just kept on blazing.
We have been wanting to do this for years, the smaller footprint of this years game and the introduction of the much cheaper VexPro gears made it possible.
Now might I ask; is the amount of friction that the idler gears add noticeable?
Oh and a big thanks to Mike Trapp at Waterjet Cutting of Indianapolis for providing the material and cutting of all the parts that made this possible (including two different iterations and a practice robot) and inspiration from 3940 CyberTooth and AndyMark from their rookie year robot.
The drive is the most quiet and smooth drive we have ever used and I challenge anyone to find a quicker or faster robot this year.
Nice setup! We built an 8 wheel drive using chains in 2010… and seeing this has me thinking that we should have used gears. In fact a 10 wheel drive would be “almost trivial” to implement using a design like this.
Assuming those are 44, 50 and 60T gears. That’s only 1.36 lbs per side in gears. This could easily be cut in half w/ basic dishing of the gears on a lathe (or not ideally, a mill).
There is some what tied up in all the shafts/bearings for the intermediate gears. Assuming 2 FR8’s per axle, and aluminum shafts at 2 inches long, this is .86 lbs per side.
This isn’t a crazy amount of weight to cleanly solve the problem.
Bold statement. I would wager 254 was quicker for sure.
What are the specs on this baby? FPS? Looks like something Aren_Hill might enjoy! Can’t wait to talk to you more & see it in action at IRI!
This might just be me being blind, but is the way those idler gears rotate just a frictional bearing between an aluminium round shaft and the hex on the gear?
Just curious, I’m happy to take your experience at face value, but did you happen to run any tests of this drive train compared to a similarly geared belt or chain one, in terms of efficiency or speed? I’m a big believer in chain/belt drives, but I can certainly see the advantages to this type of drive, especially if the efficiency is as high as other drive types.
Any plans for integrating some sort of reduction into those idler gears? You could probably make those side rails with a slick little integrated drive gearbox. It would be almost like 610’s setup, but with gears instead of chain.
Ahhhh Steampunk drivetrain. Love the gears and the different sizes.
I was pleased to hear that it’s a custom frame supporting them, so there is the quiet whirr of fully meshed gears vs mismatched gears or chains rolling around. So you’ve built the Rolls Royce of 6 wheel drive.
Can you say a few words about lubrication at the shafts and at the gear faces?
I’ll stand by it
17.3 free speed. It was as fast as we dared go on a 90lb robot without fearing constantly tripping breakers.
All shafts are on bearings and no comparison testing was done. There is reduction built into the gear arrangement and it’s driven by a custom single reduction gearbox. The reason we ran 4" wheels for the first time was to reduce the reduction needed.
Well we are sponsored by Rolls Royce
You can see the lubrication we used in the picture.
Is there a shifter in there also? Or are you a single speed drivetrain?
At 17.3 fps I hope so…
It is single speed.
This picture you posted earlier was still one of my favorites from 2013. The drive looks great, any chance we could see some CAD for it at some point? I will definitely be checking out this one at IRI.
I noticed from the first rev and the video that Akash linked to that you had problems mounting the single speed gearboxes. Any more information on what the problem was?
This would seem to imply single speed. I would be very interested to see a shifter for FRC that only needed a single reduction.