When working with gears always use an odd gear ratio. ie. 40:11 instead of 40:10 This always promotes even wear and tear on the gears.

Drivetrain
 

When working with any kind of motor it's always good to keep the magic smoke inside the case. We have always used the Drill Motor for drive and think it is a quite reliable unit when geared properly.

After last year's competition we spent part of the summer developing a new drive transmission design for our robot ED. The drive features a 1:4 ratio between low and high gears, 250rpm and 1000rpm peak power output speeds, up to 65 ft-lbs of torqe, uses the Bosch and Chiaphua motors found in the 2002 kit of parts, and an 8-millisecond response time to shift gears. The prinicpal feature is that the design can be constructed with hand tools, a lathe, and a mill. No CNC, wire EDM, castings, or carbon-carbon componsite construction capabilities are required (hopefully putting it within the reach of most teams)! We play-tested Version 1.0 of the drive system at the Maryland State Fair competition at the end of the summer, and refined Version 2.0 during the fall.

Rather than keep it as a secret, we are making the design available to any teams that want it. It is posted in the White Papers Section. Download it, build it, improve on it, or just look at the pretty pictures - it's all up to you. All we ask is that you let us know about any feedback, and if you do improve on the design, please post your improvements so the entire FIRST community may benefit and improve their capabilities. In the mean time, we are off thinking about Version 3.0 for the 2003 season...

-dave

Besides agreeing with all of your other comments I would just like to add one thing if your going to have a Good Drive train its not just the Quality of the drive train. Its the quality and know how of who works on it. We all had some part in working on the drive train on fluffy but their were a few special people on our team who know those gear boxes like the back of their hand every, screw, every gear, every sound that those drive trains make they knew them. And in our case Fluffy our robot well it was very strong and robust but at both regional and nationals we had a few problems with the drive train. Those few select people I was referring to well they put their blood sweat and tears into to those drive trains. They rebuilt our drive train in under 3 hours changed treads in 5 min, and as a freshman last year I worked with many of these people and though they don’t brag and probably don’t even think about it but I hope that they realize they are really what brings our team and Robot together under pressure. That in my view is the most important part of any good drive train. And that is the only other thing besides design that really makes a drive train come together.

I was confused by this so I asked an expert...

"If the large tooth number is evenly divisible by the small tooth number, then the same teeth will always contact each other. So if one tooth gets
slightly damaged, it will continuously wear on the same mating teeth and wear out sooner. If the numbers are not evenly divisible, then the damaged tooth will mate with every other tooth after a certain number of revolutions. Thus the wear will be spread out across the entire gear. So, it does not really have to be odd and even - just not evenly divisible. However, in our applications, this is irrelevant because we do not expect the gear mates to last for many years of constant use. A much bigger consideration is to properly design the gears for size and materials based on the loads required to be carried.

Raul"

Is this what the criteria for the odd ratio is meant to achive?

Yeah. I guess I should have explained this better. But thats the whole gist it.

ya i know.. custom stuff were: crank shaft, connecting rods, cams. actuators would be controlled by the cams hitting into some limit switches.. not a bad design.. the cam shaft would be rotated by one of those little motors we got last year and depending on how fast u rotate the cam shaft, the bot goes forward or reverse, fast or slow.. wouldnt have been IMPOSSIBLE like it was, had i had a machine shop to use ;)

Can you define "rear differential", "Ackerman front" and "swerve drive" for us?

Here is all of the info on Ackerman Steering (That you could ever want)


http://www.pbracing.com/handling/ack...principle.html

Swerve - Is pretty much the same as 4 wheel steering which could be independent, front & back, or all 4 linked to steer together. The main benefit is incredible maneuverability. Think of driving straight toward something then 'swerving' to the side to avoid it, in this case think up to straight sideways

Rear-Differential (in my mind at least) allows each rear wheel to spin at a different rate opposite of a locked rear axle, by changing the speed of the rear wheels the bot can steer

Link not working.

Try it now, for some reason the capital A in Ackerman was causing a problem

Check this out. Similar to Anthony Lapp's (team 857?) drive from last year

http://www.howstuffworks.com/gadget122.htm

NEVER use PLASTIC pulleys and 1 in timing belts.We toasted 10 belts and all the pulleys at our regional Sprocket and chain is the only way except the transmission povided this year is a no brainer..............use it Insure you fabricate a plastic cover for it to keep Foreign objects out of the mesh and lube the gear with lube from one of your old drill motors.Its special lube designed for high tooth contact loading............and PLEEZZZZZZZEEEEEEEEEE go here .www.nuts4first.net/library/Koff02drive-sys.ppt
Jim H :yikes: