Got a letter from Vernon who is having trouble with his John Deere brush hog. It read, "I bought an MX6 John Deere bush hog and the 1st time I used it in less than 30 minutes it burned up the slip clutch, so I had it fixed. The dealer said I had it too low to the ground, which is not true because it was set at about 2 1/2 inches. Im using a John Deere 5085E to pull it . After I got it back from the shop I hooked it up again and less than 30 minutes later it happened again! The dealer keep saying I'm setting it too low but Im not cutting bushes, just tough grass that hasn't been cut in a couple years. Is there any advice you can give me? I just got it back again and am afraid to try it; it's' still brand new."
I don't think this is the problem, but the first thing we need to do is to set the slip clutch correctly. The dealer has likely already done that, but we should double check his work. Here's a video on how to properly set a slip clutch: • Slipping a Slip Clutch . Once we're sure the slip clutch is right on the brush hog, there are three areas I'd look at to resolve the issue.
First, there may be such a volume of grass being cut that there’s nowhere for it to go and it’s like the cutter is trying to mow a hay bale all the time. The cutter should be set exactly as the owner’s manual outlines, it probably needs to have a slight forward rake, in other words, it’s lower at the front than the back, so the material goes out the back and doesn’t get thrown forward and cut and recut. That’s tough for a rotary cutter to do, it takes horsepower, and it could overwhelm it.
Second, I agree with the dealer that 2½” is pretty low to mow. Here, you’d be plowing and grinding up a lot of rocks and drastically shortening the life of the cutter. It’s also better on a lot of grasses to mow higher. If you mow a lawn at 2 ½” in this area the grass will be weak, and you’ll have a mostly weedy lawn. Mowing at a minimum of 3”, and better is 4-4 ½” gives you a much healthier stand of grass. If you’re in the south, you may have warm season grasses, and they tolerate a lot lower mowing height, so 2 ½” may be where you want to be. Vernon may want to mow higher one time, then come back and mow down to the desired height after the cut grass has had a bit of time to decompose. Regular mowing after that may solve the problem.
Finally, brush hogs aren’t designed to be lawn mowers, that’s what finish mowers do. Brush hogs have thick blades and are designed to make a rough cut on woody plants to weaken them, while allowing the grass to grow. It might be time to consider trading the cutter on a finish mower if the look of a lawn is what's desired and there’s no brush there. Finish mowers are a lot better at expelling cut grass.
With a 70 hp tractor on a 6' cutter, Vernon is not going to feel when the cutter is struggling from the tractor seat. If my 40 hp tractor/6' cutter was slipping slip clutches, I'd know it because the tractor would be struggling, with that much horsepower, the tractor won't feel the stress of the cutter.
If Vernon will check the slip clutch and angle of the cutter, experiment with different heights, and possibly trade his bush hog for a finish mower, I think his troubles will go away.
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