4M drive - chain wheels together or not?

We have 4-M drive train and currently chain the 2 M on each side together. I am wondering if that’s a good idea since there might be some potential motor in-fighting due to them out of sync.
Not sure what is the benefit of chain them together.

Chaining a drive can provide “more” torque for each wheel but can also introduce a lot of slop depending on how well it is tensioned. You shouldn’t have to worry about motors being out of sync if there are no coding problems. If you are trying to push another teams robot or play lots of defense, it would be better to have it chained, especially if your back wheels go off the ground a lot when pushing.

1 Like

I would definitely recommend chaining them together, just be sure to add tensioners to prevent the slop that was previously mentioned. Especially in this game with the amount of cubes on the field and obstacles in the way, putting in the extra work for the pushing power will be worth it.

1 Like

I would agree, but to be honest, unless you’ve finished everything else on your bot, you’re better off just working on the intake or something like that before chaining the wheels together. If all 4 wheels stay on the ground, then there shouldn’t be any difference.

I just see a loose part jamming a wheel, effectively shutting down an entire half of your drive

2 Likes

Yes but the biggest problem with the chain drive is that there is power required to move th extra weight of the chains and sprockets, and if a motor fails, only one side would move.

Is that even possible? you’d have to get really unlucky for that to happen. There isn’t really much that could go wrong with wheels.

Not really, but there’s a chance so it’s just another reason not to chain your wheels if your wheels are always on the ground anyway

1 Like

This can just come down to design. As long as you have a simple and effective design it will work far better. 11495B had a very strong drive train last year with a very good chain design. As long as you keep it simple it will be worth it.

2 Likes

The chance of your wheels coming off the ground is larger than something jamming the system. In my opinion at least.

I would recommend not chaining them. Really the only reason you would ever want to chain a drive is if you had to clear out some space in the front of the base. Other than that there are more cons than pros.
Pros:
-clears out space in base
-Looks more advanced… I guess?

Cons:
-Chain is susceptible to breaking and just adds another thing to your robot that could go wrong
-small gaps in chain cause give in the wheels, which makes autonomous less accurate
-It takes longer to build…

But if you’re reason is needing space in the front, then by all means, chain the drive.
It’s your decision though.

So the chain system you are thinking of is a poorly designed chain system. The best way to chain your wheels together is to have the motors mounted directly to the wheel and have a sprocket share the axel with that wheel. From there I like to chain it to the back wheels where once again the motor is mounted directly on the wheel, so if the chain breaks the motors are still being powered. To prevent slop I typically have another Adele in between the two wheels that has two sprockets connected to it. One that is chained to the front wheel and another to the back wheel, and if I want a six motet drive I can mount the sixth motors on that piece and even add a wheel to make it a six wheel drive if you wanted. This design is versatile, and has very little friction, it has the pros of the chain drive with very few of its flaws.

6 Likes

Well, you don’t have to chain them together with chain, you could use gears

2 Likes

I would definitely recommend using a gear-based drivetrain if possible. Gears are extremely low-friction, and of course have the benefit of not breaking/snapping except under extremely rare and unusual circumstances. However, If you can’t use gears (c channel brace is in the way, unusual drive setup, etc) then chain will work fine as long as the motors are directly attacked to the wheels for maximum efficiency and reliability.

This is actually the intent of my OP. We have front/back wheels individually connected (thus powered) to motors. And we also chain them together. We just want to understand the benefits of doing so.
Obviously, the drive train still works without the chain, as both motors will be controlled to operate in sync by code. We saw some teams chain front/back wheels together and some do. Just want to see any benefit of chaining.

2 Likes

some of my teams have there motors at the back of the robot (two motors driving one wheel) and then chains connecting the front and back wheel, and they have been doing this thing where the take standoffs and and connect those to the gears and drive them through the spokes on the wheels to prevent slop from the axles. so far its proved to be very effective.

1 Like

The biggest one I’ve scene is that if one of your wheels comes off the ground the energy isn’t lost, it just goes to the one wheel that still has traction. This really helps in keeping you from being high centered, win pushing matches, and plow through many obstacles. If you have the ability I would recommend you do it.

1 Like