Gear Boxes

[Teammax]

I have been reading all of the threads about drive trains that have been posted here and as always it is amazing to see the different view points and ideas. I have also been looking at different white papers that posters have recommended.

Now my question is more about the various gear boxes that I see on different robots. Over the years we have stuck the the supplied gear boxes and they have served our needs well. This year, due to space constraints and just the desire to try some new things, we are thinking we should at least look at some other options. Soooo, can anyone direct me to to any threads, white papers, pictures on gear box designs. I would love to see anything like the system that the Bombsquad used last year (and posted this season with the new wheels). Or a system where each wheel is independtly powered with a cim motor mounted vertically.

Any help would be appreciated

[SWIM]

A solution our team came up with is using the two FP's in the rear , and the two Mabuchi RS545's in the front, mated to BaneBots gearboxes, powering individual wheels.

I'll get a screenshot of the setup for you later this afternoon. The packaging is awesome: the gearbox/motors take up a space 1.5" square and ~ 4.5" deep from the inside edge of the wheel.

[mathking]

Last year for our mecanum drive we used two pieces of rectangular aluminum tubing, with two pairs of gears in each. One pair of gears connected a CIM to a sprocket and chain to the front wheel and the other pair connected a CIM to the back wheel. Thus two gear boxes actually housed four transmissions, allowing four wheels each to be driven by a separate motor. I think we still have a CAD of it, and if so I will have a student post it. This gear box was relatively easy to design and fabricate. We had to cut some openings in the top to allow easier access, but it does not require really advanced machining skills.

[Teammax]

What ever you guys can send me would be appreciated. A CAD drawing would definitely help.

[MrForbes]

That's ironic...this is the first year that we decided quickly that the kit transmissions would be just fine.

[mathking]

Here are some drawings of the gear boxes we used last year.

[Jon Stratis]

This year is kind of funny. In the off-season, the mechanical team played around with the Dewalt shifting transmissions (there's a white paper on here somewhere for those), since being able to shift last year would have helped a lot. Now they announce the game and we say "hmmmm.... shifting transmissions don't seem to be so important this year." So this year our gearboxes will pretty much be determined by space constraints. Some gear boxes, like the Dewalt's, are longer but narrower, while the KoP gear boxes are much shorter and wider. Which one fits better within the size constraints? I'm just a lowly programmer, so don't ask me! Other than that, i don't think i can say much, or the team members will hit me tonight for giving away team secrets.

[Teammax]

During the off season we spent time working on drive systems where our focus was on different wheels and different programs but using the same basic gear boxes. We even purchased a wide variety of wheels even though FIRST emailed all the teams about buying equipment before knowing the game.

Sadly all of our work goes to the back burner until (maybe) next year.

I do agree that the KoP gear boxes would do the job. For the team it is more the space 4 gear boxes take up along with the orientation. For me personaly I want to just try something different and see where it goes. Even if we have to throw out the idea and bolt on the KoP boxes in the end.

[EricH]

Originally Posted by Teammax

I do agree that the KoP gear boxes would do the job. For the team it is more the space 4 gear boxes take up along with the orientation. For me personaly I want to just try something different and see where it goes. Even if we have to throw out the idea and bolt on the KoP boxes in the end.

Any particular reason why you can't use only two and run chain or belt to an extra wheel?

[Jared Russell]

www.banebots.com still sells a wide array of CIM gearboxes

www.andymark.biz now sells planetary CIM gearboxes, as well.

[Jon Stratis]

Originally Posted by EricH

Any particular reason why you can't use only two and run chain or belt to an extra wheel?

You certainly could, and with the surface and wheels this year i doubt you get any additional power, speed, or acceleration from driving each wheel independently. However, for a traction control system, driving the wheels independently does increase your ability to detect and correct slippage...

[Teammax]

Yes, because some of the programming work is set around comparing wheel speeds and adjusting individual motor speeds. So (hopefully) each wheel will have a different motor.
Also, the drive chains would pass through areas already designated for our
gathering system. Not an impossible fix but we need to get away from our standard drive system or change the gathering system.

As a side note a great example of a space saving system is at the top of the page:

http://baxterbombsquad.com/whatisfirst.htm

[SWIM]

here you go:



that's a mabuchi RS-545 with banebots gearbox mated to a kit wheel

[Cory]

The Banebots planetaries do not like side loading-I would support the other end of the shaft if you want to direct drive them.

[SWIM]

Originally Posted by Cory

The Banebots planetaries do not like side loading-I would support the other end of the shaft if you want to direct drive them.

That design uses an external bearing block with an R8 bearing (mcmaster PN 60355K15) to support the shaft. That would certainly help, wouldn't it?