When I worked for the pulpwood company, we looked at different ways of de-limbing the Virginia pine I layed down in fan shaped bunches with the Franklin feller buncher, and one way was a skidder-type of machine that had instead of a grapple, a huge spinning cylinder with chains attached almost like a giant wire brush or wire wheel, but with chains in stead of wire. You would lower this spinning drum with its slinging chains down and ride it down the trunks laying on the ground. The idea was the flaying chains would knock the limbs off the pines, so the ground guys didn't have to do it by hand with saws before the grapple skidders took it to the yard. It actually worked, and had an added benefit that it partially de-barked the logs too, but of course it didn't knock off the limbs facing down against the ground. We decided against that system though when one of the chains broke off of the spinning cylinder, and flung itself into the ground, buried itself several feet deep. Just imagining what a flying chain would do to an unlucky ground guy, or even the machine operator if it broke off was enough to kill that idea as too dangerous and we opted out. Don't remember what kind of windshield the thing had, I think it had a chain link though in front of the windshield.
Dave