pic: Concept 8wd Drivetrain

[B.Johnston]

One way to avoid tensioners is design.

Not that you can see the chain in the pic I attached.

We:

1. used sprockets with an even number of teeth.
2. spaced them apart a multiple of the chain pitch (#25 = 1/4")
   our axle CL to CL = 10"
3. changed the chain loop when it stretched to sag more than 3/8"

And to answer Cory:

Originally Posted by Cory

I'm always curious why so many people cite the desire to have a robot that can continue driving through multiple chain/sprocket/etc failures. In the hundreds of matches my teams have competed through, as well as our collaborative partners, I have only ever witnessed two chains break-in both cases it was a sprocket failure.

If your drivetrain is well designed and the chains are properly tensioned, the odds of losing a chain, let alone more than one chain are nearly negligible.

Here's why I like redundancy and fault tolerance.

2006

2nd match of the Greater Toronto Regional (Finals)

We're(1680) up on 1114 by 1 match

30 seconds in our driven transfer sprocket shatters kinking the chain.

We spin in circles for the rest of the match.

now even 1 -1 against our sister triplets (this was an amazing tank system)

Change the broken sprocket with a replacement (from 1114 BTW)

Third match in autonomous we throw the chain...

The rest is history.

With redundancy and fault tolerance you shouldn't be susceptible to these sort of events.

Those who fail to learn from history will repeat it.