The perfect gearbox

[Ben Piecuch]

While I like the 2:1 or 2.5:1 ratios that most gearboxes provide, I REALLY like the 3-speed ratios that the Dewalt's provide. Using the CIM, it provides 3:1, 4:1 and 12:1 ratios, and only requires the use of one motor. The "stump puller" ratio, as I like to call it, gives plenty of torque with a one motor setup. (Granted, at the sacrifice of a bit of speed.) While the other two ratios provide plenty of speed to get across a wide open field, a la this 2006 game...

Overall, the planetary setups provide the smallest, lightest packages possible. Let's face it, 3/8" face, 50 tooth gears are never going to be the lightest for a FIRST robot. Look at the success of the Banebot's gearboxes this year. Cheap, light, small, and a lot of people are using them, even though their quality may be a bit questionable... Make a similar gearbox for a drivetrain (with a bit more robustness) and I think you've got a winner.

My only gripe about most gearboxes is that they take up a lot of volume. Specifically, they tend to be quite wide. Folks using an off-the-shelf gearbox for their onmi-drive setups, or even just a standard 4wd find that the overall length of the motor + gearbox setup becomes very long. Andy Brockway and the 229 crew have solved this problem nicely with their gearboxes. Maybe something like that can be integrated into a planetary setup.

Also, if you look at Wildstang's, Simbots, or even Beatty's (and I'm sure others') custom drive gearboxes on all their swerve setups, you'll find a beautiful, lightweight package. Let's see the whitepapers on those bad-boys!

I believe the kit gearbox is brilliant, and why some under funded, under manned teams shy away from it is beyond my grasp. It's a tough package to beat for reliability and ease of use. You need to match it's performance and ease of use if you want to sell into this group.

Though, overall, I think a lot of work can be done to help teams integrate their motors into a nice, off-the-shelf gearbox. The motor rpm's this year are either really fast, or really slow, and teams are finding that it's tough to get something running in the 500 to 1000rpm range with a small, light package. Adapter plates, mounting brackets, etc... take the pain away from teams with just a drill press and a hack saw.

I know this got a little off-topic, but I think making things easier for the smaller teams will greatly increase the competitiveness of all the robots. If you can make it easier, AND add a performance increase (through a shifting transmission or whatnot) you'll find yourself with a winning package.

BEN

[team222badbrad]

Originally Posted by Gdeaver

I always liked the ball shift gear box that team 222 uses. Never liked the idea of smashing gear teeth together.

Thanks, we built another one this year and its better than ever!

We have not released our 2006 transmissions yet, so here is a sneak peek, but I think we came close to what this thread is asking!

They are smaller than the KOP transmissions, have two speeds, easily changeable gear ratios, can use one or two CIMS per transmission, and they weigh less than the KOP transmissions.

See them at VCU!

[Veselin Kolev]

As some have requested, here are some pics of the 2006 HRT Team 1072 drivetrain I described earlier.

[lukevanoort]

I have a few dream 'boxes for different purposes.

General use: A two speed dog (Woburn style) with aluminum gears (more on these later) and a polycarb/aluminum shell. Now to explain my odd materials choices, the polycarb would be ultra thin, whereas the aluminum would be beefy. Now the aluminum would make a crisscross structure supporting only the high load points (eg the bearing mounts) and forces (eg the mounting holes) on the gearbox. The polycarb would mostly to keep garbage out, it could even be saran-wrap. The aluminum gears wouldn't be strong enough especially considering they'd be milled for lightness, except for some tricky chemistry. Drop them in a vacuum chamber with H2 (hydrogen) and CH4 (methane) at 50 Torr, add heat and voila! diamond coating. Or you could just pay a company to do it, whatever.

Insane use: A Thunderchicken CCT with the aforementioned polycarb/aluminum structure and lightened diamond plated aluminum gears. It would be driven by the bike chip, and two small chips with the FP providing the ratio control function.

Insane use 2: This box also uses polycarb/aluminum/diamond coating construction. It uses a ball bearing shifter with three planetary gear selections. It is powered by the bike chip, two small chips, and the FP (maybe a Globe and window motor too!) Bring on the twelve motor drive!

Absolutely Insane use: Okay, time for my nuttiest idea yet. There is a central gearbox that matches ratios between all the motors in the kit (except that crummy Mabuchi motor) to, say 500 rpm. There are then two separate sets of CVT v-belt assemblies. These allow for the speed on one side to be reduced to, say 50 rpm, with the other side doing 300 rpm allowing for skid steer turning. This could also have four CVT assemblies for holonomic. Yay! as many motor as you have drive!

It's times like this when I wish we had more money and machining capability.

[vansivallab]

hey
are the dewalt gearboxes compatible w/ the CIMs?

[EricH]

Originally Posted by vansivallab

hey
are the dewalt gearboxes compatible w/ the CIMs?

Yes, with some modifications. See the Nothing But Dewalts whitepaper for details.