Rotary cutter recommended PTO confusion

[MinnesotaEric]

I am curious about this too; working through whether to repair a JD MX5 (medium duty) in great shape, or abandon it, and go as heavy as I can find.

I understand you've got to be able to turn the blades, and manage the weight on the back, but getting one started doesn't take much, and bushhogs with recommended even 50% higher than my PTO minimum output still are only at half the hitch capacity.

If the driveline protection is in place to slip appropriately, why couldn't you run a heavy duty instead of a medium duty? I see a nice unit, 280# heavier, cat 5 drive, but its asking for 50hp at the pto, and I have 30.

Any experiences with this?

My 48 PTO tractor easily runs a Woods BB720X which is recommended to have 30-120 PTO hp.

At idle, turn on the PTO, dial up the throttle to PTO power speed, and away I go. I didn't video mulching 3-4" poplar stands but it went right through them.

 

[brown40]

The match I was contemplating was a bush hog 325 on a JD 3520... 1200# machine where now I have under 900#, but twice the gearbox rating, larger driveline... basically I don't think my machine could generate enough force to tickle that unit. Just have doubts about powering it.

Medium duty was all I needed & was rated for twice the hp I could put out... still it broke, so I guess I'm thinking pay a bit extra & only buy it once. Course that's what I was thinking the first time, so if I could never hope to hurt it (doing reasonable work), that would make me feel more secure using it.

 

[Poopdeck Pappy]

Consider that your tractor's 3 point hitch lift capacity is rated at the lift arms or slightly behind it. But look how far behind the lift arms the weight of a heavy cutter is hanging and think about the fulcrum effect on your tractor.

Also, even if the light, medium and heavy duty versions all use the same blades (which is doubtful), the blade pan they attach to would be much more massive and heavy on the heavy duty version versus the light duty version.

I wouldn't use a cutter that had a minimum HP rating much higher than the PTO HP of my tractor. I can probably replace a torn up or worn out cutter cheaper than I can split my tractor apart and fix a torn up PTO. All it would take is one time of hitting something with the slip clutch not adjusted right.

 

[LD1]

The match I was contemplating was a bush hog 325 on a JD 3520... 1200# machine where now I have under 900#, but twice the gearbox rating, larger driveline... basically I don't think my machine could generate enough force to tickle that unit. Just have doubts about powering it.

I think you could power it just the same as any other cutter of the same size. The issue will be lifting it. With 1200#, I would want to leave the FEL on and/or weights. You 3PH is rated a good bit higher than mine. And I carry an 1100# 6' cutter. With the 325 being a 5' cutter, keeps the weight closer but a tad heavier. Again, I think the 3PH will be fine, but considering your tractor dont weigh much more than mine, will be very light up front.

All it would take is one time of hitting something with the slip clutch not adjusted right.

Same can be said for any cutter that isnt adjusted properly.

 

[Soundguy]

I don't understand ......The rest of the widgets, frame and wall gauges, etc, has nothing to do with what it takes to drive the blades.
?

Respectfully.. I'd call that incorrect assumption.

if you take a light duty 6' mower and a heavy duty 6' mower. you can have almost a 2x difference in weight!

that extra weight is carried by the tractor.. it accounts for more mass and inertia needed to move it and control the tractor. too light a tractor and you can get a 'tail wagging the dog' stuation. in general terms.. the higher you go up on hp.. the heavier the tractor is.

For instance. my ford 3000 and my ford 4600. by the book, only about 15hp seperates them. mid 30's to high 40's hp. the 3000 is fine for a light or medium duty 6' mower.. however i have a ultra heavy duty old 6' mower on the 4600 that the 3000 won't even lift.. in fact.. the mower weighs 2/3's PLUS the weigth of the 3000. the 4600 on the other hand totes the heavy 6' mower fine.

both mow 6' swaths.... but the mowers require differnt hp tractors to get different size range tractors.

 

[Spindifferent]

I am curious about this too; working through whether to repair a JD MX5 (medium duty) in great shape, or abandon it, and go as heavy as I can find.

I understand you've got to be able to turn the blades, and manage the weight on the back, but getting one started doesn't take much, and bushhogs with recommended even 50% higher than my PTO minimum output still are only at half the hitch capacity.

If the driveline protection is in place to slip appropriately, why couldn't you run a heavy duty instead of a medium duty? I see a nice unit, 280# heavier, cat 5 drive, but its asking for 50hp at the pto, and I have 30.

Any experiences with this?

If you decide to go with a different unit, I use an older Frontier RC1072 with my JD 3520, and it works great for light to medium applications. That model has been rebranded as the RC2072.

 

[Texasmark]

Well I learned one thing the hard way. I high centered a Mohawk once on a terrace and ripped the center box out of an 8' dual blade mower. Tractor was 100 hp and the box, I found out later in "trying" to replace it, was only rated at 45 hp. So whatever you buy, have the box rating exceed the tractor's capacity.

Mark

 

[Reverser]

Respectfully.. I'd call that incorrect assumption.

if you take a light duty 6' mower and a heavy duty 6' mower. you can have almost a 2x difference in weight!

that extra weight is carried by the tractor.. it accounts for more mass and inertia needed to move it and control the tractor. too light a tractor and you can get a 'tail wagging the dog' stuation. in general terms.. the higher you go up on hp.. the heavier the tractor is.

For instance. my ford 3000 and my ford 4600. by the book, only about 15hp seperates them. mid 30's to high 40's hp. the 3000 is fine for a light or medium duty 6' mower.. however i have a ultra heavy duty old 6' mower on the 4600 that the 3000 won't even lift.. in fact.. the mower weighs 2/3's PLUS the weigth of the 3000. the 4600 on the other hand totes the heavy 6' mower fine.

both mow 6' swaths.... but the mowers require differnt hp tractors to get different size range tractors.

Soundguy, I've had a similar experience. :thumbsup:
I have 40hp Case-IH that's about the same size as your Ford 3000. A while back, I got rid of a 6' medium duty Bush Hog that I had used until it was becoming too worn out to repair. At the same time, I ran across a good deal on an old 6' Servis(Rhino) rotary cutter that had belonged to the county. They were the same size and I thought they both would handle the same.
Boy, was I wrong. :thumbdown:

Right away, I could tell there was a world of difference in the weight between the two. When I went to pick it up, the front end of the tractor reared up. So I put some heavy weights on the front end, and it would pick the mower up but I could tell it was straining. It also struggles more going up hill in heavy grass than it did with the lighter cutter. And I'm sure it's putting undue stress on the tractor.

That old Servis is a great mower, but was meant for a bigger tractor. The deck on it looks to be as thick as my box blade.

 

[Soundguy]

the mower i was refering to is also a servis/rhine OLD hd 6' job!

ps. even on my 4600, i had to load the front tires, and add front wheel weights, and build a front brush guard to get the weight so that when the tractor was climbing the steep angle of the beavertail on my GN trailer , that the front end didn't point straight up!

when i loaded it the first time i had to use brakes to steer going up the trailer ramps. as it is a tall deckover.. that wasn't a fun feeling.

 

[Reverser]

WOW!!! Now that's a coincidence. :laughing: