Using sprockets to rotate arms/intakes etc

So like if you look at 254 this year, their intake could rotate through a sprocket. I know this is used by other teams but I don’t get how they attach the sprocket to the intake so that it rotates the intake. Anyone care to explain?

With a plate sprocket, you can use the sprocket’s bolt pattern to bolt straight into the tube. Then support the tube/sprocket with bearings on a dead axle. You may need a spacer to separate the sprocket from the tube slightly to give room for the chain to clear.

This is generally preferable to using a live axle for arms. With this dead-axle setup the axle sees no torsion load, only shear load from the weight of the arm. With a live axle setup the axle also feels a huge torque from the load working a significant distance from the pivot point, which can twist the shaft (aka twizzeler-ing).

Ah I see. Where can you get plate sprockets from?

Andymark and VexPro have some:

I believe VexPro has 25 chain plate sprockets too.

in 2018 we used gears to move our arm. Beware that chain drive can introduce lash and increase shock loads. Especially as the length of chain increases.

I’m not sure if you’ve read through their 2018 technical binder, but there is a better picture than most others of just their intake mechanism.

Send me a PM and we can supply you guys with a few, or you can just come to our shop and have your pick. 103 has accumulated at least a drawer full of various plate sprockets over the years. We’re not so far away either.

If you decide you need them, you also might want to reach out to 25 who is pretty much up the street from you (North Brunswick HS). I would find it hard to imagine they don’t have a few plate sprockets lying around (even though their drivetrains are usually all gears).

Can you elaborate on the “increase shock loads” claim? I was always under the impression that chain reduced shock loads compared to gear drives or direct-drive.

This is not my experience. Compared to many other types of power transmission, namely gears, chain provides relief from shock loading in the general case if it is sized appropriately. Chain has some amount of stretch to it and that stretch acts to spread the load out over a longer period of time, creating less of an impulse (shock).

From Tsubaki Complete Guide to Chain

In the product conveyance industry runs of chain are often used over direct or gear drives to lessen shock load from sudden stops or accelerations.

Thanks for the offer. I’ll keep it mind. Just asking so I know how it works for season in case we end up needing it.