Rotary Cutter Rotary cutter gouging

[Genereynolds]

As I don't own a tractor (yet) I pay a couple of guys to mow my property with a rotary cutter. The property is more like pasture than lawn. One of the guys uses a large Massey (fifties model), the other has a large, newer JD. Both use 6' cutters.

Invariably, after a mowing by either one, there will be several instances of a shallow furrow several feet long caused by the cutter deck digging into the ground. Is this normal and a fact-of-life with rotary cutters or can it be prevented by proper adjustment and/or technique?

I'd like to think that when I begin doing my own mowing I can avoid the problem.

 

[MChalkley]

Gene, it's pretty common with the heavy duty rotary cutters because the front of the cutter's height is determined by the three point hitch height setting. That means the front of the deck is liable to dig in when the front of the tractor goes over a hump or the back drops into a hole. You can minimize this a bit by keeping the front a little high. The best way is to get a pull-behind rotary cutter that has front wheels, too, but they're expensive.

 

[W5FL]

I had a lot of problems with this with my Massey. I finally got a set of check chains that held the front of the cutter up and would not let it go down any more than the chains were adjusted to allow. This solved 90% of the problems that I had. The Massey 3 point leaked down pretty bad and that did not help. Keep in mind that if you turn really hard with a cutter on the rear then it matters whether you turn up hill or down to minimize any gouging from the edge of the mower.

I do not have check chains on the Kubota and do not need them. A rotary cutter is recommended by the manufacturer to be set lower in front than the rear to lower the HP necessary to drive it. If you set it level or raise the front a little, the gouging problem is reduced and if the cutter has uplift blades, the cutter tends to mulch and this takes more power to run, but does a better job. Most cutters actually set on the rear wheel for the rear setting and on the three point for the front setting. the top link should be adjusted for the maximum amount of flexing possible and still allow you to pick up the cutter. This allows the mower to follow the contour of the land better.

I am using a Bush Hog 286 medium duty cutter and have it set about 1 1/2 inch high in the front and 1 inch high in the rear. It has chain guards on the front and rear and cuts very nice.

 

[Bird]

Gene, you'll probably learn a lot about avoiding that problem with a little practice. And different makes and designs of rotary cutters can make a difference, too. I'm generally partial to Bush Hog brand products, but when I had 48" Squealer, I occasionally gouged some places, too. With the 5' Howse I have now, that very rarely happens. I'm not sure just how to verbally describe the difference, but the "A" frame 3-point hookup on my Bush Hog could swing forward and backward (hinged at the bottom), with a chain from the top of the "A" frame to the rear of the deck. The Howse has a very rigid, heavy "A" frame and the top link hole is a slot rather than a round hole. Of course, I set the rear cutting height with the rear wheel, lower the 3-point to the desired front height, then adjust the length of the top link to the center of the slot on the cutter. That allows the front of the cutter a little up and down movement as the tractor's rear tires go into low spots or over high spots, but if the tractor rear wheels go into a very low spot, the 3-point will "float" up when the top link pushes back against the "A" frame on the mower. I believe the newer Bush Hog also has a rigid "A" frame now. And I'm not sure I'd understand what I just said, if I hadn't seen the rig in operation/w3tcompact/icons/smile.gif.

Bird

 

[Genereynolds]

I'll bet the answer to this is obvious but I'll go ahead and let my inexperience (continue to) show. It seems that most 3ph finishing mowers are supported on all four corners by wheels, pretty well preventing ground contact by the deck. Most small to medium size rotary cutters on the other hand, have only a single, trailing wheel allowing the potential for the front of the deck to dig in on uneven terrain.

Why the difference?

 

[Bird]

Gene, the short answer to your question is: I don't really know; hadn't thought much about it. But how about this? The brush hog is more frequently used in rough terrain where more wheels would get tangled in brush, saplings, etc. The wheels on brush hogs are generally traveling on already cut ground behind the blades (except when you back it over saplings and brush you don't want to, or can't drive over). And while the blades are much heavier, the overall weight of the brush hog is less, and a comparable brush hog costs about third as much as a finish mower; more wheels would add to the cost.

Bird

 

[W5FL]

The small wheels of a finish mower would be quickly damaged on a medium duty rotary mower. The rear wheel is extremely rugged and I have had one of them to come off while mowing.

I expect a rotary mower to cut anything that will go under the tractor. The blade is 1/2 inch thick x 4 inches wide and will cut rocks in half much less small brush.

I actually saw more of a problem with my old Massey 2WD with the front wheels skidding and tearing up the grass on hard turns than with the mower edges tearing up the grass. /w3tcompact/icons/frown.gif The Kubota 4WD does much better. /w3tcompact/icons/smile.gif

The tip speed is approx 200 mph for many rotary cutters and that cuts pasture grass as well as a finish mower would.