Rotary cutter / "position control"

Capricious · Jul 17, 2014

I know nothing of tractors, and have never operated a rotary cutter / brush hog / Bush Hog / schredder etc.

The tractor i have purchased is an old Mitsubishi with "position control." As I understand it, the lever controling the hitch can
be moved to any position within its arc of motion, and the hitch will move to, and stay at, a similar position in its arc of motion.
The tractor has an adjustment that can be changed to speed up or slow down how fast the hitch drops (no down force) but no other
controls for the hitch.

I have a rotary cutter for this thing. Do I set the height of the front of the cutter using the position control, and just leave the lever alone, relying on the hydraulics to keep the front of the cutter at the same height, or do I want to install chains that the front of the cutter hangs on, in which case do I leave the position control in "full-down"? As far as i can tell, there is no "float" option which would allow the hitch to rise over bumps and allow it to fall to the limit of the chains. If the hitch should rise (due to a lump in the ground) with the lever in "full-down" is their an issue with the cylinder pulling fluid due to the vaccum created, when normally the cylinder would be exhausting fluid with the lever in that setting?

Thanks.

TripleR · Jul 17, 2014

Here is a helpful video for new owner/operators. If you don't have a manual for your cutter, you can often get an online down load. There are also many old threads on adjusting a rotary cutter. Land Pride has a good description on proper adjustment. If this doesn't help, please advise.

"How To" Operate and Drive a Tractor: Part 1 - YouTube

Texasmark · Jul 17, 2014

Position control is used for all conditions other than plowing like would be done with a moldboard.

Draft control causes the implement to lift slightly upon encountering obstacles like rocks or tree roots or soils where you go from little resistance to heavy and back and forth. Rather than bog your tractor down or possibly cause it to flip over to the rear, the 3rd member is connected to a pressure sensor inside the tractor and pressure against this spring causes the 3 pt to lift.

Mark

Poopdeck Pappy · Jul 17, 2014

Capricious said:
. . . As far as i can tell, there is no "float" option which would allow the hitch to rise over bumps and allow it to fall to the limit of the chains. If the hitch should rise (due to a lump in the ground) with the lever in "full-down" is their an issue with the cylinder pulling fluid due to the vaccum created, when normally the cylinder would be exhausting fluid with the lever in that setting?

. . . .

With very few exceptions, no tractors have 3 point hitches that apply downward pressure on the 3 point. The only downward pressure is due to the weight of the implement. If the tractor or mower runs over a rise in the ground that exerts upward force on the mower, it will come up . . . at least to the highest limit of the 3 point hitch's travel.

Gunny · Jul 18, 2014

Most of the time I've seen check chains used are on tractors where the 3 point can't hold the implement at the proper height during operation (looses pressure), but they are quite handy because once you set the length of the check chain, then it's "set and forget". They do add a little time and work involved with hitching up, but nothing significant.

madmax12 · Jul 18, 2014

A rear finish mower, with wheels front and back, allows the the three point hitch to be in float, without having to think about it. I haven't used a rotary cutter, so I'm not sure how you prevent the front of the rotary cutter from digging into the ground.

A perfectly flat mowing surface wouldn't be complicated. However, mowing in and out of dips and over bumps would add complexity.

Capricious · Jul 18, 2014

".. mowing in and out of dips and over bumps would add complexity..."

That is exactly what I have. Rocky Missouri Ozarks terrain that was cleared with a dozer about a dozen years ago, and then recleared (mostly by hand) by me over the past (3) years. I have picked & piled most of the larger rocks and cut-off low most of the stumps from trees that sprouted after the dozer work, but some of the holes were the dozer took out stumps still remain, and the terrain is a bit "rolling" although this is on the edge of the Ozarks so no real extreme terrain.

My main concern is trying to go as easy on this worn out old tractor as possible. If i can "hang" the cutter from chains rather than relying on hydraulics, I would like to do that.

Capricious · Jul 18, 2014

Another dumb question; Do all rotary cutters have shear bolts/ shear pins if they do not have a slip clutch? i have an older 42" Kubota model 342 cutter (that looks a lot like a Bush Hog-brand "Squealer") and it does not have a slip clutch, nor does it appear to have a shear bolt. The input shaft for the cutter gear box is splined and grooved for the same type of quick coupler that the tractor-end of the PTO shaft uses, so there is no shear bolt there. And I have looked at the universal joints on both ends of the shaft and am not seeing the type of shear bolt that runs parallel to the shaft through 2 little "'ears"

Texasmark · Jul 19, 2014

Capricious said:
Another dumb question; Do all rotary cutters have shear bolts/ shear pins if they do not have a slip clutch? i have an older 42" Kubota model 342 cutter (that looks a lot like a Bush Hog-brand "Squealer") and it does not have a slip clutch, nor does it appear to have a shear bolt. The input shaft for the cutter gear box is splined and grooved for the same type of quick coupler that the tractor-end of the PTO shaft uses, so there is no shear bolt there. And I have looked at the universal joints on both ends of the shaft and am not seeing the type of shear bolt that runs parallel to the shaft through 2 little "'ears"

Some shafts have an overrun clutch built into one end on such a configuration as you mention. The over run clutch is dual purpose in that on overload, it slips so there is your protection. You can tell the ones with this function as the two ends are different with the overrun end much wider than the other with a separate grease zerk. ASC sells them and I have one on my IH 404 crimper.

Mark