That's a great combination! I bet you can really move some dirt! Do you have top/tilt? Its on my must have list.
Yesterday I finalized measurements and cut a skid plate out. This morning I mounted the skid on top of the FEL subframe. It fit perfect and will keep the soft belly of my tractor from getting damaged by the brush. I will take it off later and paint it. I also managed to get that 7' Craigslist bush hog up and running this morning including setting the clutch and a thorough greasing.
On to the seat time!
During the test run I found blades are a little out of balance but its ok to go ahead and use it today and then get some new blades.
I started out with some easy 1" fairly heavy brush. At 1500 rpm you couldn't really tell anything was being cut. Just a little slap here and there when a branch hit the side of the hog. After all the little stuff was cut and the hog still humming along I moved over to the trees. Its basically a forest of 8 to 10' tall 2 to 3" trees. It was pretty dense and more that I would have ever tried to cut with a light weight hog. Besides, I just wanted to give it a try.
I should have taken pic's. This bush hog cut right through these trees. You could tell you were cutting some serious stuff but the hog didn't jump around hardly at all and only once in a while would the 4155 show any signs of a load. Even then it would pull right through. With the HST I was able to feed the trees in slowly and give the hog time to shred everything. I guess this bush hog is pretty heavy duty and 4155 is more powerful that I thought. The only limit is what I'm willing to drive the tractor over which isn't anything bigger than this stuff.
I would not drive over brush like this without a skid plate. I feel certain you would pull off or bend up some of the piping or damage one of the filters under there. I did have to watch the pins on the lift arms where they attach to the tractor. I lost 3 of those pins to the brush. I will probably replace them with bolts since I don't really need to take them off and losing one could damage the lift arms.
Oh, almost forgot, I unhooked the upper link on the 3 point and just used the hog like a trailer on the lift arms. I figured that would be less stress on the tractor. It seemed to work just fine. With the cylinder on the tail wheels I could continually adjust either end of the hog for better cutting depending on the situation. I learned that I could raise the back all the way up, let the front all the way down and back over just about any tree under 4". Some of those I would back into just enough to cut them off then leave them lay.
Last thing that's maybe some help. I've read on here several times that a 7' bush hog is "too long". Well, since it is long, I can back further under the trees and get at more underbrush. So like most things, there are advantages and dis-advantages. For me this almost too big for my tractor bush hog is great and a keeper. Now if it was just LS Blue.......