D'ni mining winch-thing?

[Emor D'ni Lap]

a worm drive system might work, similar to the one in the Backgammon age's dice cage.

You're right.
A worm drive would be the perfect thing to prevent back-driving the winch when the cable is under tension. But they aren't often used in places that get really dirty, because the grit abrades the surfaces of the worm gear, eventually stopping the whole thing.
Anyway, I had already done most of the work on this weird chain drive setup, so here's a couple shots of it so far:


So, this rather imposing chain is just made of a single alphaed .png panel repeated in 3 dimensions. Both chains add up to about 600 tris.
(the chain looks a little odd right now, I think because it's the only thing in the scene that's textured!)

But I think the main wheel needs more vertices; it still looks way too angular to be believable. It's 800 tris right now and may need to double that, we'll see.

Hope this is all okay by you, Ben.