Drivetrain Questions

[Cow Bell Solo]

Originally Posted by roboticWanderor

Hey there CD, just thinking of some drive train ideas. and was wondering how to do a few things
had a few questions:
what is the best way to tension toothed belt/roller chain?
we have had real problems with chain and belt tension in past robots and it's a problem i want to try and address next year

We used some short pieces of 80/20 and put some roller that we attached to it you can kind of see it here

Your best bet is to use adjustable tensioners, as chains (and probably belts, although I have hardly any experience with them) will stretch as the competition wears on. I would suggest a sliding idler sprocket (nylon is good).

There's lot of threads on this subject so a quick search would also be helpful.

[Aren_Hill]

this year we managed to find on ereplacementparts.com the old style drill to interface onto a fisher price, some parts took awhile to get here however. you can still buy the old drill

[Richard McClellan]

Originally Posted by roboticWanderor

Hey there CD, just thinking of some drive train ideas. and was wondering how to do a few things
had a few questions:
what is the best way to tension toothed belt/roller chain?

we have had real problems with chain and belt tension in past robots and it's a problem i want to try and address next year
and....

Here's how we tensioned our chain this year:
http://www.chiefdelphi.com/forums/sh...ad.php?t=64009
On the right is our drivetrain tensioner which we haven't had any problems with at all. It's continually adjustable just by moving the shaft up and down and tightening the position with two nuts on top and bottom. The only time our chain jumped off is when one of our IFI wheels failed. The hole for one of the wheel bearings expanded by about 3/16", and caused the wheel to wobble all over the place (hence the chain jumping off) so we had to replace the wheel.

On the left is #25 chain tensioned by a turnbuckle, which actually failed right before ship day because the eye loop that we had closed, opened up. We ended up hacking on a hose clamp to pull the van door motor shaft up - not the most elegant solution, but it works.

Originally Posted by roboticWanderor

does anyone have cads, or dimensions on the new XRP dewalt transmissions (they don't sell the old ones) available?

Our team used the DC940s this year on the drivetrain with great success. The main difference is that the hole pattern on the yellow housing is slightly larger. 624 was gracious enough to post the dimensions so we were able to start making the parts even before our transmissions arrived in the mail: http://www.chiefdelphi.com/forums/sh...9&postcount=17

The dimensions of the piano wire linkage may also need to be adjusted, we made ours to fit and didn't really look at any dimensions.

[A_Reed]

Chains, you can typically do with some kind of delrin runner or wheel that is adjustable and easy to access for spot checks and tensions between matches. you can also use a screw tensioning system where you draw back or push froward a block that either holds you wheel or sprocket.

Belts are basically the same and require good tensioning practices to continue to work properly, if not they are liable to break. we on 48 have used basically the same method ever since '06 on our treads and have only broken a few pairs since. it involves putting a screw tensioner into the system, but instead of moving one of your delrin wheels or an idler sprocket you are moving a splined toothed pulley.

I don't have the models or any pictures on my computer but I know of a few people who, if you ask nicely will help you out. one of them is Mike Mellott, he was the head designer on our past couple of models for treads and we be the one to tell you how to use some form of screw tensioning system, the other two I don't know personally but probably know allot more than I do about drive train design and they would be, Craig Hickman and Madison Krass. look up some of they're work, I know one of them has a 6-wheel drive with a build in tensioner. remember they are probably busy with schooling and they're teams so do searches and some research before asking for explanations. most of the material can be found on CD.

I will try to find some of my old material and post it also.