[Donut]

Ah, sorry for late responses to these questions! I haven't logged in to CD in a few months now since I graduated and am getting used to the college experience.

These are all store bought parts for the tensioner, with the exception of that metal plate which is of course from the KOP. It's simply a nylon sprocket (#25 for our chain) inside of a clevis rod end, though you might even be able to do it with the ends of the pneumatic pistons as mentioned. These ended up costing around $17 per tensioner.

Below the chain is our cart, just a nice metal cage like some metal shelving in stores.

Come to think of it I don't remember how we stopped these from rotating, but I know it wasn't really anything special, I believe they're just held on by the screw going to them.