>Have you checked out the friction coefficient for concrete, vis a vis
>granite on polished limestone?

No! But I would be interested if you have the calculations proving otherwise.

>I think you'll find the difference might just make up the difference.

Keep in mind my ramp is at 30.2 degrees not 26.5.

So just for the record are you saying that the granite plugs would slide down the ascending passage by gravity?

RLH