Chain and Sprocket

I recently made a large purchase, and it’s coming in tomorrow. It contains the chain and sprocket kit.

Out of curiosity (and because I don’t want to have to wait until I build something to test it), can the chain pull objects, or is it just for transferring motor power to areas far away from the driving sprocket?

If it can pull objects, about how much of an incline (at full motor power) can it pull a tennis ball?

Would the tank treads be more efficient at creating a motorized lift?

How do you find/what’s the formula for the torque/speed of the chain?

:eek: Wow, I ask a lot of questions! Thank you for your help.

I’ve never personally used the chain to pull objects, but I have seen it used to create a lift, so it is clearly possible.

As for moving tennis balls, I think this is exactly the kind of thing the new tank tread upgrade kit is intended for. Have a look here.


  • Dean

The simbots used chain to help with their intake of tennis balls. Mostly though the chain was used to simply roll the tennis balls. I’ll see if I can get a picture up.

I guess it’s too late, because you’ve already bought the kit…but I’d like to say that


It often breaks, it’s made of plastic, so you should use it only in non-critical applications (when it comes to your competition robot). You can find out for yourself, when you end up rechaining after every match at a tournament…but I wouldn’t recommend it. If you have to use it, make multiple redundancies (put 4 chains between 8 sprockets instead of 1 between 2).

Can the upgrade kit make a full tread on its own (1 kit?), or do you need to be the tank tread kit?

You really need the tank tread kit before you can make use of the upgrade kit.
The upgrade doesn’t include the sprocket or idler wheels used to drive and guide the links. It just has the grey traction links and the rubber divider flaps.

You can use the VEXplorer tank treads which is slightly cheaper, but you don’t get as many idler wheels. Personally, I’d go for the regular Vex tank treads if you can spring for the extra $5.


  • Dean

You could potentially get by with just the upgrade kit but I would suggest getting a regular kit too.

Quzar beat me to it, what he said…

Looking at the upgrade kit, I’m trying to think of a way to get this to work.
The fins would be able to support the tennis ball on the track, but… how would the tennis ball be able to get on the tread with the fins in the way? It could get over the fin, but the spring action would throw it back (possibly). Also, it could cause some tread lag if it doesn’t have a big enough space to go under while it revolves, but making a big enough space would allow the tennis ball to fall through. I guess when I buy the kits I’ll have to experiment.

Anyone have an example of using the fins in a conveyor-belt like style?

If you’re trying to elevate tennis balls then use some intake rollers, then put the tank tread above the intake rollers. I’ll write out a very limited diagram (O = ball, | = tank tread, # = roller, \ = curved metal plate).

| O |
| O |
| 0 #
\ O O O

Your robot is driving -> that way. The O’s should be bigger; you want the intake roller at ball height, and you may want to use a curved plate to roll them up off the ground.

Why does that make perfect sense O.O
I really have to be more creative.

Wow, It works perfect for me!
Maybe your issue is that it isn’t taught (as in stretched out, I don’t know the spelling) enough.

I’m using to the drive train for a robot I’ve code named Big (will probably change once I make it’s function). Without the chain, i’d have to use about 8 36-tooth, 1 60 tooth, and 2 twelve toothed gears- for one side. I wouldn’t have enough gears for the other side.

So, I have to say I’m very impressed with the chain and sprocket kit.

Chain is pretty useful for some stuff, like what you’re using it for, but it does tend to break if put under too much pressure. An early design of my team’s used a sprocket-driven drive train and arm. We never had any problems with the drive train, but the arm chain tended to snap off and hit random passerby in the face.

Also, dear lord that bot sounds MASSIVE! What do you think the final dimensions will be?

Maybe I exaggerated a litttleeeeeee bit.
Its not as huge as you think, it’s probably about the size of the average teams Bridge Battle bot.
Currently with wheels, chassis, microcontroller, battery, and transmitter, it is:
12.5 x 12.5 x 5 inches

For your purposes right now, it’s fine, but remember that when you’re on a field, with your robot pushing as hard as it can on opponents, chain is not a good option. By the way, Abra Cadabra IV’s FTC robot this season was a lot bigger than yours (no offense :)).

Chain works when more speed is being transfered than power. Also you never want to be using chain if you might be stalling out the motor.

And Bellpride’s was a lot bigger than ours. It wasn’t too unusual to see robots severely pushing the 18" size limit throughout the season.

Chain does have it’s uses. We have used it twice now as part of an arm. That said, it is still very weak and if at all possible tank treads should be used in it’s place.

I Have never had it break ether

I think proper chaining will help to prevent any chain breakage during competition. Used it to chain 3 motors to 2 large wheels in competition without any issues, using larger sprockets and double set of chains.

ive never used chains before but my alliance partners did (FTC 104 and 106) i believe they both had problems with their chains