Attempting the impossible

[Cl4p-tp]

Thats right, a chain-less drive train for an off season project. Any ideas?

[Andrew Schreiber]

What do you mean impossible?

Why? Have you considered using timing belt? (See 125 in 2008 if I recall)

[Bmcdonnell]

Our team is attempting to achieve this over the summer, well at least we are thinking about trying to try it...

I'm not really sure how we would do this though because I'm not on mechincal, but I'm hoping we succeed. Our chains broke in our final matches in Atlanta.

[Chris Hibner]

Team 51 used a chainless drive this year. It was 4WD and each wheel was gear driven by its own motor. The motor/gear/wheel assembly was made as a module and could bolt on to any corner of the robot.

[RogerR]

Better not tell Raider Robotix (team 25) its impossible; they've been doing it since 2003.

see also: 703, 1369, 103

[sanddrag]

May I ask why?

[BEEKMAN]

well i always did think that mechanum wheels were somewhat witch-craft....most of them are direct driven off a gearbox..no chains

[Josh Drake]

Ours also had no chain, but that's easy with belts.

[Bruceb]

how about using shafts and bevel gears
Bruce

[BrendanB]

1517 was a belt drive this year, mecunams normally don't use chain as BEEKMAN said, I think 126 had a belt drive in 2008, and pretty much it is not that hard to have a chainless drive.

What type of drive are you guys considering? It does sound like a neat project to use something you haven't done before, I guess that is why they call it off-season, belt, direct drive, sprockets, other?

[sdcantrell56]

We used timing belt this year to great success. I still have to question why you are so adverse to chain. Properly set up, you should never break a chain. Maybe instead of finding an entire new way of transmitting power you should look at improving your current chain setup and figure out why it didnt work. If something was wrong in the chain setup, you will surely have the same issues with belt or direct drive as those really require even more precision and thought.

[thefro526]

Originally Posted by Bmcdonnell

I'm not really sure how we would do this though because I'm not on mechincal, but I'm hoping we succeed. Our chains broke in our final matches in Atlanta.

Can you or someone else on your team elaborate on this a little bit more? I'm curious to how you actually broke chain, we've done some interesting (dumb) stuff with both #25 and #35 chain and have never actually broken the chain.

Usually, when teams have problems with chains it's because of implementation and not the actual chain itself. Proper alignment and tension have solved any issue that I've ever had with chains.

But, on the original topic, having a drive train that doesn't use chains is uncommon but not impossible. Personally, I'm biased towards the 25 method of building drive trains around gears, and I think I may experiment with this a bit in the off season. On thing you may want to consider about moving away from chains is that you'll need increased precision in your implementation to use just about anything else. I've found that #35 chain is pretty forgiving to loose tolerances, but gears and belts aren't...

[artdutra04]

Originally Posted by Bmcdonnell

Our team is attempting to achieve this over the summer, well at least we are thinking about trying to try it...

I'm not really sure how we would do this though because I'm not on mechincal, but I'm hoping we succeed. Our chains broke in our final matches in Atlanta.

If your "chains broke" in several matches, going chainless (unless you only have four wheels, each direct driven) via gears/belts will only make the problem worse. Gear and belts need higher tolerances than [35-pitch] roller chain does.

If your chains broke, it's probably because they were improperly tensioned or misaligned. Look at solving these problems before you write off chain and attempt something else. If you don't solve the root causes behind your chain failures, the same issues will affect whatever other drive train design you implement.

[Cyberphil]

Team 103, which I am proudly a part of, has beed using relatively the same drive train, which is completely gear driven, since 2007. We were inspired by our long-time friends, 25, and built a whole now drivetrain as an offseason project after the 2006 competition. We were also sick of the problems with chain and decided to revamp our design. We have had no serious problems with our drivetrain since then. Our system has been nearly flawless, and has proved us very well. This year we are planning to make a few modifications to lower the weight, but otherwise, a very solid drive train.

We modified our system in 2008 and 2009 to deal with restrictions and increase speed.

I am confident to say that we have one of the most powerful, allong with one of the fastest tank-style drivetrains in the FRC behind a few powerhouse teams.

If you have any specific questions, please pm me.

[DarkFlame145]

Direct drive, good power, but drains batteries like crazy and if the drive shaft gets bent your in trouble.