Need Advice: Rotary Cutting and Finish Mowing

MarkV · Nov 27, 2004

Dave,

I tend to agree with what a couple others have said about not getting to crazy with the power recommendations. When you think about it the manufacture has to make his power recommendation on the high side to cover so many different types of uses. If I am buying a 6’ rotary mower to clear over grown power lines and need to cut 2” sapling at production speed I’d bet their recommended 30 PTO hp. would seem a little skimpy. On the other hand, in your case you are cutting established grass that you plan to cut once every 2 weeks during season and that just doesn’t take the same amount of power. If the grass gets away from you one month then cut at slower travel speed and take 4’ passes instead of 6’ passes.

The general rule of thumb for rotary cutters has been 5-6 PTO hp per foot of mower, depending on who you talk to. With my little tractor I would need a 2 ½ foot mower. /forums/images/graemlins/frown.gif The 4’ light duty mower I use has never caused my tractor to bog down and I have cut fields that the grass/weed was taller than the tractor canopy. It has also worked its way through areas of 1” – 11/2” sapling without complaint.

More power is always good! Will the 28 hp tractor run the 6’ mower even though it has 2 hp less than recommended, in my opinion, absolutely. If it makes you crazy not to follow the manufacture recommendations get a 5’ rotary mower and a 6’ finish mower.

Not knowing the tractor you are considering the other part of this equation is the ability to lift a 6’ rotary mower. That size rotary mower hangs way behind the tractor and weighs a lot. Make sure you have enough lift power and enough counter weight on the front to handle than much mower.

MarkV

JClark · Nov 27, 2004

Dave,

Last summer I got tired of bouncing my 60" MMM around my 3 acre field for 3+ hours everytime I cut it. I talked my local Land Pride dealer into letting me try a 72" rear discharge finish mower by promising to use it for no more than 10 minutes. It only took 5 minutes to realize that my little 17 pto hp 4110 would have no trouble at all powering that mower and it never went back to the dealer.

In thick 10" high grass I do have to slow down some but the rest of the time I travel full speed in the low range of the HST at 2600 rpm.

For your light duty uses I am confident you can use a tractor of some 10 or 20 percent less pto hp than the recommend amount for those mowers.

have_blue · Nov 27, 2004

Don't know about the finish mower, but I pull a 72" RC with a 35 HP tractor just fine. Just don't let the weeds get too far ahead of you!

FLDave · Nov 27, 2004

Thanks for all of the valuable information. I am becoming a little less "squeemish" about the 28 hp PTO unit I am considering. A few more good answers and maybe I'll finally be ok about not buying a 40 hp PTO unit.

DK35Vince (Vince)-Your tractor is in the exact hp range as the one I'm considering, what model KingKutter 72" rotary cutter are you using and are you happy with it?

Roy-From the latest spec sheet, your JD790 is rated at 27 hp with a 24 hp PTO If you had 4 more hp PTO would you feel ok putting a 72" Land Pride Light Duty rotary cutter on ("power-wise" not "weight-wise")?

Keeney (Rick)-Shouldn't the forward speed that your tractor is in while cutting only depend what you are cutting since the PTO is always going 540 rpms (on level smooth terrain of course)? Therefore a bigger tractor using the same cutter theoretically won't cut any faster than a smaller tractor using the same cutter?

MarkV-You must know me. Yes I am very **** (I like to call it thorough /forums/images/graemlins/tongue.gif) about not overworking an expensive piece of equipment. But then again, how many people actually change their cars oil at exactly 2,500 mile intervals all of the time? I see what your saying. It's ok to go a little overboard just don't go crazy is what I am getting out of your statement.

Jeff-How is the 72" finish mower holding up? How fast can you cut your 3 acre field now and what cutting height do you use? I'm sure it looks sweet with a finish mower cutting it. Do you religeously have to mow all of the time now or can you let it get a little ahead of you and still get it back under control? At what height grass do you say to yourself "I had better cut today or I am in big trouble?".

Have Blue-Your TC35 has a "smidge" more PTO hp than the unit I am considering. When you say "RC 72" " which model Woods are you referring to?

Here's a thought (and not an original one I'm sure /forums/images/graemlins/tongue.gif), what would you guys thing of me using one of those WOODS RD Series finishing mowers to do the yard AND the pastures? Say like the RD7200 or the RD8400?

Or better yet, how about the WOODS RM990? The manual I downloaded says, "The Woods RM990 rear discharge mower is tough yet versatile enough to move from rough weedy farmland to commercial lawns and landscapes." It's got a 90" cut, has a 1 1/2-8" cutting height range, weighs 930 lbs. and has a 25-50 hp tractor compatability. It probably cost a fortune to boot. Does anyone think this could possibly be a good "do-all" cutter for me?

Thanks, /forums/images/graemlins/cool.gif

Soundguy · Nov 27, 2004

( Can you tell me out of these manufacturers how many 72" rotary cutters are made that are rated for a 28 hp PTO? )

Make sure you aren't confusing the max pto hp rating on the mower gearbox, for what it needs to operate. For instance.. you can get a KK 5' hog with a '40' hp box.. it doesn't need 40 hp to run.. rather that is the max you can deliver to it safely.

Old Ford N series are 5' rotary cutter machines... they have between 26 and 27 hp at the engine.... that give you any ideas? ( 23-24 pto hp is what you would pretty much want as minimum for a 5' mower ).

If your tractor is small.. use a more economy mower such as a kk or howse, as they are lighter duty, and weigh less.

Soundguy

Soundguy

Dutch445 · Nov 27, 2004

Dave,
What reason are you thinking you need such a big finish mower for 3-4 acres? I would expect a 60" mower in an open lot to mow it in about 2 hrs or so. If you step up to the 72", cut that down to less than 2, depending on how open the area is. If you had a rugged 72" mower, you certainly can mower meadows and pastures if there isn't thicker material, and you keep up with it by mowing once a month or so. All of the mid size tractors would have no problem running a 72" 3ph mower, and most would lift and run an 84, although your quality of cut decreases with any rolling hills in the area thats mowed.
If the rougher areas aren't just grasses now, you could hire somebody to come in and cut it down with a heavier rotary cutter once, then as the lighter grasses grow keep it in check with the grooming mower. I think the Woods, Frontier, Land Pride, Befco or many others will work well, but if you are headed into the pastures step up into the heavier built models. (they each offer different grades of mowers)
I tend to think a 4310 would do the job very well, a 4410 adds a little more HP for tougher conditions, but from the sounds of it you probably wouldn't horse the tractor that much anyway.
It does sound like you have narrowed your tractors to include Deere. I'm sure you would be happy with one and either mentioned above will serve you well.

good luck!
/forums/images/graemlins/cool.gif

RoyJackson · Nov 27, 2004

"Roy-From the latest spec sheet, your JD790 is rated at 27 hp with a 24 hp PTO If you had 4 more hp PTO would you feel ok putting a 72" Land Pride Light Duty rotary cutter on ("power-wise" not "weight-wise")? "

If I wasn't concerned about the weight, I'd put that 72" cutter on the 24 PTO HP 790. As mentioned, for the lighter brush, I'd take a full width cut. For the sections that were heavier, or if the tractor was bogging excessively, I'd slow down or run a pass or passes using half to two thirds the cutter width.
Back to the finishing mowers for a moment... I know I could easily use a 72" finishing mower. If my lawn was big enough (I've only about an acre of lawn), and the weight of the finishing mower didn't exceed the 3PH capacity, I'm sure I could use an 84" mower deck.
However, I've got the mower and cutter I'll be using for the next few years (for the cutter...unless I really screw up...that'll go for the next ten to twenty years). If I had the funds, I'd trade up to a 72" finishing mower in a heart beat!

Just use some common sense when you use this equipment.

DK35vince · Nov 27, 2004

( DK35Vince (Vince)-Your tractor is in the exact hp range as the one I'm considering, what model KingKutter 72" rotary cutter are you using and are you happy with it? )

I am running the King Kutter L-72-40-P (I'm pretty sure anyway).
It is a 72" cutter with the 40 HP gearbox. Cost was around $695, I added a slip clutch for around $95 more.
I don't like sheer bolts so I added the slip clutch..
Once I lowered the lift pins 5" (the originals are to high) and drilled a new hole for more tailwheel adjustment I have been happy with this cutter.

FLDave · Nov 27, 2004

Soundguy, I was using the "Recommended Tractor HP" on the cutter spec sheets.

Dutch445-I was thinking if I got a commercial grade or heavy duty finish mower that I could take care of my entire 15 acres of pasture with it. I'd of course set the cutting height to at least 5" in the pastures. What do you think?

Roy, thanks, so you don't think a bigger cutter would suck up too much hp or hurt the PTO if driven modestly?

DK35Vince-Thanks, that's a pretty good price for a do-all cutter. But again, how long does it take you to do you 3 acres of field?

No comments on the Super Duper Woods RM990? /forums/images/graemlins/wink.gif

Thanks, /forums/images/graemlins/cool.gif

EddieWalker · Nov 27, 2004

I went about buying my set up a little differently. First thing I knew that I wanted was a bush hog wider than my tires, so 72 inch was were I started. I don't have an brand loyalty or preferences. I talked to Kubota, Deere, New Holland, MF, and Century tractor dealers. To run the shredder the size I wanted they all said I needed to be aroudn 30 PTO hp.

Next consideration was weight. The shredder weighs so much, and the tractor has to be heavy enough to handle it. My tractror is border line and I had to add weights to the front to keep the front tires on the ground when going up hill. It was a real problem when trying to turn.

If I did it again, I'd go for more HP. You can never have enough, and you can always find a use for more power.