pic: Mmm ... Greasy Worms :-P

A peek into the heart of our drivetrain this year. Its our first year to use non-kitbot trannies, and aside from uniqueness - this unorthodox solution had some nice features that tided us over in our design.

Any others out there with a setup quite like this?

well we don’t use the worms, but we do use the shnazzy pvc spacers. Do you have any other pics of this drivetrain? I would like to see why you are using a worm gear.

Would this be because the gears won’t backdrive when you are being pushed, so your wheels will lock up?

are you using a copper worm gear? is the gear that the worm gear mates to copper?

Nah, worm mating gears are almost exclusively bronze or brass, in order to permit the two gears to mush together a bit, creating a smoother running setup with less backlash.

That is what it is. I for some reason thought that they were made out of copper, but now that you say brass or bronze it all clicked.

Just to warn you, that these 2 metals are relatively soft. If to much force is exertaded onto them, it will strip the 2 gears.

This is our gearbox for our wings in 2003. However we started noticing severe wear at our first regional. By the time we got to nationals we new that it was pretty well gone. The brass gear that you can be seen (the gear that is cut to only 1/4 of a gear) was completely stripped.

Now i haven’t thought about it in so long, and i don’t know the exact force that was working against the gear, but im pretty sure that it is less than some robot will be pushing against you with.

Hopefully you thought it all out before deciding to do a worm gearbox.

Good luck and let me know how it turns out

The small gear is steel, the large gear is bronze. This is a good way to make a worm gear system, I would not worry about it. And the grease is another sign that they know what they’re doing…

That grease won’t help them if they collide with another robot at high speed… I remember from 2004 and prior about people using the drill motors with their gearboxes, without removing the anti-backdrive pins, and completely destroying the internals during impact with other teams.

I would at the very least look into the fact that there may be a problem down the line, and ways to fix it, if I were them.

The red grease makes it look like a meat grinder. Which I happen to think is really cool :wink:

I would have to agree

As far as worm gears go, its a relatively low reduction. We used a quad-thread worm - which really makes it roughly halfway to a helical gear set. This means it is backdrivable, but is notably more resistant than standard gearing. Also the quads appear to be able to take greater stresses than comparable single or double threaded worm gears, although I don’t particularly know why.

It is a bronze worm gear with a hardened steel worm, as mentioned in previous posts.

I have checked the numbers as best I can and I think they’ll hold up to the abuse that the robot is bound to see, but we’ll be running them in and doing some heavy testing in the next week or so to see how they hold up. The biggest unknown is the shock loading like Cory mentioned, so this will be something we will test for. There is still room for some changes if they don’t seem to be holding up well enough - but for now we’ll just keep those in our back pocket until the need arises.

Just to warn you- in the past we’ve had difficulty turning with worm gears.

The meat grinder effect is really cool though.

Your robot learned first hand that these worms worked in a high speed collision, thanks for the bumber by the way… I have got to get around to mounting it!