Chain or gear drive?

Hello! We’re wondering about drive trains. So far all of our drive trains have been driven off of chain and sprocket. This year we were thinking about making a drive train using all gears to transfer power from the gearbox to the wheels. I was wondering if any of the teams that have tried this in the past have any thoughts on the pros and cons. Thanks!

It is getting kind of late to make that decision. :stuck_out_tongue: Chain is cheaper and easier to do. I have heard some arguments for gear drives but have yet to really hear one that I like (other than reliability, which is true for any correctly made drivetrain).
At this point you may want to opt for KOP chassis just to save time.

Pros: Strength and better long term reliability, No chance of belt or chain breaking or becoming misaligned.

Cons: Cost is vastly higher I would imagine, Weight would for sure be higher, and Gear drives need to be constantly lubricated. Gear drives can also be very loud. I’m also pretty sure that creating the plates that the line of gears would have to mount to, depending on how you did it, would have to be precision machined.

Most of my FTC drives were all gear driven, but I would imagine FRC gear drives would be very much more expensive. My FRC experience is limited to Belt & Chain so you’ll have to wait for someone with more expertise to come alone.

I haven’t used it so I can’t recommend it, but there is a COTS all-gear 6 wheel drive available from AndyMark. As noted above, it’s heavy and expensive. If you want to go down this road, you may want to use this or just examine it for ideas/inspiration.

Edit: We have used nanodrive, just not the all-gear. Kind of strange to assemble, and the gearbox is not fully enclosed, but our air cannon (which is quite a bit heavier than FRC legal) runs well on it.

Don’t forget about belt drive trains. You have to make sure you order the correct sizing, but they have been pretty reliable for us.

Won’t the $400 upper limit prevent a team from using that chassis? Did they remove that rule this year?

That’s actually a really good question. I wonder if this chassis isn’t intended for competition use, but rather as an off season learning tool?

Does it count if most or all of the components are individually purchasable? You could (extremely easily) purchase each gear and wheel and bearing on its own and come up with the same product. Does that mean you have to?

REad the rules, you might find that if the individual components can be used in different configurations, and you buy several components that work for your configuration, for under 400 each, it’s ok. But if the components can only be assembled into one configuration, then you have to keep the price of the whole thing under 400.

From the web page, it looks like it’s a one shot deal, and it costs over 400, so it would be illegal. But that’s just my interpretation.

we started using belt drive a few years ago and we will NEVER go back to chain.
with the correct spacing you never need a tensioner. Set it and forget it.

It’s legal. Each of the individual components are <$400. It literally has a list of components that you can buy individually. You could put together those components in several different ways. How many different ways can you use a CIM motor? Or a washer?

We have done gear drives in the past and will also be doing it this year. We love the reliability. We haven’t had a single failure with these drives.

Yes it’s expensive, building up an inventory of gears and bearings over time has significantly reduced that cost for us but initial cost is high. The Vexpro AI gears are extremely durable and usable year after year.

Lubrication is no more of a problem than any other gearbox. A tiny bit of grease before every comp is all we have ever done.

Heavy? Maybe, maybe not. #35 chain is heavy, #25 and belts would be lighter but we haven’t had any troubles with weight and what ever extra weight there may be is right where you want it.

Yes, gear spacing is critical. Some form of CNC machining should be used. We have a great sponsor in Waterjet Cutting of Indiana.

Like anything new, I would recommend off season testing for something you are trying for the first time but if you have confident CAD skills and a way of machining it, go for it.

We’re going for it, the gear trains certainly are a beauty.

benefits of chain: Light, cheap, relatively easy to assemble
Benefits of gears: Reliable, quick change of direction, little maintance

I’m curious what you’re gearing your belt-drive bot to, and what kind of belts/pulleys. We just switched to chain after several years of belts, because in very-high-torque pushing matches our 15mm HTD belts would jump even with laser-cut center-to-center mounting plates (and then even with delrin tensioners).