Those macs looked positively insane bouncing their way to destruction.
The torque on those motors must be insane, they don't slow down a bit as they crunch whatever into oblivion!
I was thinking this could be a great torture device. Get your prisoner to put his hands against the wall and he has to walk on one of the rollers. It won't be too many hours before the poor guy is so exhausted he will tell you anything.