Rotary cutter / "position control"

[Capricious]

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]

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]

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]

. . . 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]

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]

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]

".. 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]

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]

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

 

[TripleR]

Here is a picture of a slip clutch model and shear pin.

 

[SSdoxie]

The 3 point lift cylinder is not pined to the lift mechanism in the tractor, it only pushes on a lever that in turn forces the lift arms lift as the cylinder extends. Regardless of where you have the lift arm height set, the lift arms can be pushed up moving that internal lever away from the cylinder so arms can raise. Then when the external push force is released the lever moves back until it hits against the cylinder and stops downward movement. So with a rotary cutter you have the position control set to hold say 2" above ground, the rear wheels drop in a 4" hole and the cutter hits the ground, it will push the arms up preventing any lifting force applied to the arms and not trying to raise the tractor. When the rear wheels climb out and back on level ground the cutter drops back to height you have set.

 

[Capricious]

I am not seeing the compbination over-running coupler/slip clutch @ ASC, but did see this, which would be an easy (but not real cheap) fix:

FD1 PTO Slip Clutch-1-3/8 In. 6 Spline | Agri Supply #31951

Easier to install than replacing a unversal joint yoke. And, if it should turn out that the PTO shaft has been shortened to the extent that it is now too short for my aplication, the slip clutch might solve another problem.

 

[Gary Fowler]

I had an overrun clutch on my Yanmar and it only slipped in one direction. It allowed the PTO to continue spinning when I clutched without pushing the tractor forward. It will not slip in the power direction so it is of no value as a slip clutch or safety mechanism to prevent damage to your tractors PTO.
I have never seen a bush hog that didn't have at least a shear pin for protection. Some of them will just be two flanges mated together. Each will have a small hole in them that has to be aligned and a bolt inserted of a specific size and grade. The bolt size will fit snugly into the two holes and Grade 5 is a commonly used bolt.
TO THE OP: Please post a photo of your bush hog PTO shaft with particular attention at the end where it attaches to the bush hog gear box. That is where the shear pin will be located.

 

[jeff9366]

If i can "hang" the cutter from chains rather than relying on hydraulics, I would like to do that.

Positon Control returns 3-Pt to exact position it was in before, so position is repeatable. Most small tractors do not have Positon Control.

Here is a link to my thread reviewing check chain installation on Kubota B3300SU supporting a 48" King Kutter Rotary Cutter:

http://www.tractorbynet.com/forums/...ta-b3300su-zerco-check-chains.html?highlight=

Check Chain function, in lieu of Position Control, was highly satisfactory.

 

[Capricious]

I had an overrun clutch on my Yanmar and it only slipped in one direction. It allowed the PTO to continue spinning when I clutched without pushing the tractor forward. It will not slip in the power direction so it is of no value as a slip clutch or safety mechanism to prevent damage to your tractors PTO.
I have never seen a bush hog that didn't have at least a shear pin for protection. Some of them will just be two flanges mated together. Each will have a small hole in them that has to be aligned and a bolt inserted of a specific size and grade. The bolt size will fit snugly into the two holes and Grade 5 is a commonly used bolt.
TO THE OP: Please post a photo of your bush hog PTO shaft with particular attention at the end where it attaches to the bush hog gear box. That is where the shear pin will be located.

This is a photo of just one end, but both ends of the shaft are identical:


In fact, I am not sure which end is supposed to be the tractor end, and which end is the cutter end. The cutter gearbox has a splined input shaft identical to the PTO output shaft of the tractor. The cutter gear box input shaft is not smooth.



Neither end yoke on the shaft is set-up for a shear bolt, in the manner that this yoke is:

1486037 6 Lc6 Shear Pin Flange Yoke

 

[Capricious]

Not a good close-up, but this is the cutter. One can barely see the splined input shaft. Definetly no slip clutch or shear pin @ the cutter gearbox. And nothing on the driveshaft itelf.



The guy was simply running it without any overload protection. But, I don't think it was run very much. The tractor that it was used with developed a bad case of black sludge in the fuel system.

 

[k0ua]

This is a photo of just one end, but both ends of the shaft are identical:
View attachment 383504

In fact, I am not sure which end is supposed to be the tractor end, and which end is the cutter end. The cutter gearbox has a splined input shaft identical to the PTO output shaft of the tractor. The cutter gear box input shaft is not smooth.



Neither end yoke on the shaft is set-up for a shear bolt, in the manner that this yoke is:

1486037 6 Lc6 Shear Pin Flange Yoke

In my opinion those cutters that have the 1 3/8 splined input shaft are setup for a slip clutch. Some one has removed the slip clutch and just put a 1 3/8 to 1 3/8 shaft on it so you have no protection at this time. You need to buy a slip clutch and fit it to the cutter.

 

[TripleR]

Look at these, it shows parts diagrams for shear pin and slip clutch.

http://www.landpride.com/ari/attach/lp/public/manuals/326-047p.pdf

 

[Capricious]

"...In my opinion those cutters that have the 1 3/8 splined input shaft are setup for a slip clutch. Some one has removed the slip clutch and just put a 1 3/8 to 1 3/8 shaft on it so you have no protection at this time. You need to buy a slip clutch and fit it to the cutter...."


That scenario would make sense: the cutter was purchased new by someone who used it very little, and it sat for several years before a second person bought the tractor & cutter. I am the third owner of the cutter, but the tractor had already been traded-off by the second owner (who could never get all the algae cleaned out of the fuel system.) I would bet it is likely that the slip clutch was on the tractor, and went with the tractor. I say this because i also bought a 5ft angle blade that had been part of this package, and the blade came with the top link from the original tractor, so I imagine that parts and pieces were not staying where they needed to stay. That would all make sense.

 

[k0ua]

"...In my opinion those cutters that have the 1 3/8 splined input shaft are setup for a slip clutch. Some one has removed the slip clutch and just put a 1 3/8 to 1 3/8 shaft on it so you have no protection at this time. You need to buy a slip clutch and fit it to the cutter...."


That scenario would make sense: the cutter was purchased new by someone who used it very little, and it sat for several years before a second person bought the tractor & cutter. I am the third owner of the cutter, but the tractor had already been traded-off by the second owner (who could never get all the algae cleaned out of the fuel system.) I would bet it is likely that the slip clutch was on the tractor, and went with the tractor. I say this because i also bought a 5ft angle blade that had been part of this package, and the blade came with the top link from the original tractor, so I imagine that parts and pieces were not staying where they needed to stay. That would all make sense.

Normally the slip clutch stays with the rotary cutter,/PTO shaft. the slip clutch usually has half of a PTO yoke on one end and a 1 3/8 splined female fitting on the other. But for some reason, they removed the slip clutch and found an old PTO shaft with 1 3/8 on both ends and put it on, or something similar. In any case you don't have any protection. so if you hit something immovable, something is going to break. It could be PTO components in your tractor.