Whats the big deal with in tube gearing?

[cad321]

This thread isn't meant to an insult to any type of drive train or style of building, merely a genuine question. Over my time on chief delphi I have seen countless numbers of drivetrains where the gears are all on the inside of the tube their chassis is made from. What are the benefits to this? To me this would seem like a poor decision as it makes maintenance on your sub system difficult at best. Should you strip a gear or need to lube up your transmission, it is very tight with little to no openings. Speaking of tight space, getting the gears inside the tubing to begin with seems like a challenge. Surely its doable (heck teams do it) but it seems like it would take an incredible amount of time ensuring they're seated correctly before it is assembled.

Again this is just me trying to understand the benefits to other designs to aid in the build in years to come. In no way do I feel that this style of building is bad, I may even find I prefer it once I've heard others opinions. Obviously all designs differ slightly, but this seems to be a common theme among a lot of them.

[Mike Marandola]

The main advantage is that it saves space. This year, some robots needed the extra space for the totes to fit inside their chassis. It also opens up more options structure wise. For example, this large cross member on 254's robot wouldn't be possible with a traditional WCD. Other benefits are chain protection and aesthetics. Of course it would be up to your team to decide if the extra space is worth the challenge.

[GeeTwo]

While I haven't done one of these drives, I believe that protection (both of and from the chain) is the biggest advantage. Aesthetics and volume savings also contribute. One other point I noticed in a post was that if the tolerances are calculated correctly, it becomes nearly impossible for the chain to come off the sprocket without something breaking due to the limited clearance.

[Abhishek R]

Originally Posted by cad321

This thread isn't meant to an insult to any type of drive train or style of building, merely a genuine question. Over my time on chief delphi I have seen countless numbers of drivetrains where the gears are all on the inside of the tube their chassis is made from. What are the benefits to this? To me this would seem like a poor decision as it makes maintenance on your sub system difficult at best. Should you strip a gear or need to lube up your transmission, it is very tight with little to no openings. Speaking of tight space, getting the gears inside the tubing to begin with seems like a challenge. Surely its doable (heck teams do it) but it seems like it would take an incredible amount of time ensuring they're seated correctly before it is assembled.

Again this is just me trying to understand the benefits to other designs to aid in the build in years to come. In no way do I feel that this style of building is bad, I may even find I prefer it once I've heard others opinions. Obviously all designs differ slightly, but this seems to be a common theme among a lot of them.

Do you mean the transmission gears itself are in the tubing, or the chain, or both?

[cad321]

Originally Posted by Abhishek R

Do you mean the transmission gears itself are in the tubing, or the chain, or both?

I have seen both done. Already these responses are very good points I hadn't considered.

[Abhishek R]

Originally Posted by cad321

I have seen both done. Already these responses are very good points I hadn't considered.

I see. We ran the chain-in-tube design this year on our robot, and it was great. Since the chain can't go anywhere (due to the constraints of the tubing) we didn't have to do any maintenance on it at all, and it went through 3 regionals and Championships fine, still running great as we head into the offseason.

Like others said, it was actually integral to our design as we needed the space to fit our elevator system and totes into the robot. Another hidden benefit was the fact that noodles couldn't get stuck in our chains as we saw with some other team because none of it was exposed.

Even installation wasn't that time consuming; we actually finished our drivetrain this year faster than any other year, getting the practice robot drive chassis done within a week into the build season.

[Justin Montois]

340 first did Chain in Tube in 2012 and it was a learning experience. The main advantage was the gain of internal space and the aesthetic of a clean looking robot.

The installation of the chain the first year was a pain but we've gotten much better at it over the years. The size of the pockets, the order of installation, and the right combination of tools really makes all the difference.

If you're looking for an offseason project I would definitely recommend giving it a shot.

[Sperkowsky]

Is there some sort of tutorial as this seems like a cool off season idea

[bigbeezy]

Originally Posted by Sperkowsky

Is there some sort of tutorial as this seems like a cool off season idea

Seconded. We are working on a t-shirt cannon this off season and having the chain in the tube might be a good safety feature in addition to keeping dirt and other debris out of the chain. Do any teams use belt inside the tube?

[Dunngeon]

Originally Posted by bigbeezy

Seconded. We are working on a t-shirt cannon this off season and having the chain in the tube might be a good safety feature in addition to keeping dirt and other debris out of the chain. Do any teams use belt inside the tube?

It's possible, but you'd have to use 2x2 tubing to get both of the belts to fit into the interior. From what I've read on Delphi, chain in tube is better than belt since chains (rarely) snap and don't stretch over time, eliminating the need for a tensioning system.

[cadandcookies]

Originally Posted by Dunngeon

It's possible, but you'd have to use 2x2 tubing to get both of the belts to fit into the interior. From what I've read on Delphi, chain in tube is better than belt since chains (rarely) snap and don't stretch over time, eliminating the need for a tensioning system.

While chains do not stretch over time like belts do, they do wear over time, which has a very similar effect. For the most part in my experience neither phenomenon is typically noticeable in a robot during a standard (1-2) event season, but both can be observed on a practice robot with sufficient hours of use. In a high-use demobot, both have a potential to give you issues if you use it long enough.

Both chain in tube and belt in tube have been done successfully in competition-- 1625's Lobster Drive and of course 118's chain in tube come to mind as examples of belt and chain respectively.

[Cash4587]

I could be wrong, but I am pretty certain chain definitely does stretch over time, more so than belts. Due to the fact roller chain has metal pins and bushings that all see general wear and tear, I think chain elongates the more use it sees.

[Ty Tremblay]

319 hasn't made a chain-in-tube drivetrain yet, but what I find attractive about the design is it's simplicity and the volume savings. It may be a little less easy to work on, but due to the protected nature of the chain, the odds of you having to work on it are smaller. Mounting gearboxes becomes much easier as well.

Originally Posted by Cash4587

I could be wrong, but I am pretty certain chain definitely does stretch over time, more so than belts. Due to the fact roller chain has metal pins and bushings that all see general wear and tear, I think chain elongates the more use it sees.

Under the forces it'll see in FRC, chain cannot stretch. It can wear, however.

[Lil' Lavery]

Originally Posted by Mike Marandola

The main advantage is that it saves space. This year, some robots needed the extra space for the totes to fit inside their chassis. It also opens up more options structure wise. For example, this large cross member on 254's robot wouldn't be possible with a traditional WCD. Other benefits are chain protection and aesthetics. Of course it would be up to your team to decide if the extra space is worth the challenge.

That large cross member would be possible with exterior chain/belt, you'd simply have to route the chain around it*.

*Which obviously comes at the price of additional chain and idlers.

[Dunngeon]

Originally Posted by cadandcookies

While chains do not stretch over time like belts do, they do wear over time, which has a very similar effect. For the most part in my experience neither phenomenon is typically noticeable in a robot during a standard (1-2) event season, but both can be observed on a practice robot with sufficient hours of use. In a high-use demobot, both have a potential to give you issues if you use it long enough.

Both chain in tube and belt in tube have been done successfully in competition-- 1625's Lobster Drive and of course 118's chain in tube come to mind as examples of belt and chain respectively.

I'm more concerned about the chance of snapping a drive belt, rather than the wear. It's nearly impossible to snap chain in FRC if assembled correctly, from my (limited) experience it's quite a bit easier with belts.