Rotary Cutter / Bush Hog Considerations for Compact Tractors

[jeff9366]

Will_C said:
"I know it had been discussed many times on TBN, and the general consensus is 5 PTO hp for 1 foot of bush hog size. Wondering if anyone has real world experience with a L3560 and a "2 inch" capacity bush hog. I need a 6' cutter to cover my tracks- tractor is 70" wide- but worry if I'll be underpowered. I do trust my dealer, and he says I'll be fine with a 6' cutter."


You will be find with a RCF2072 behind an open station L3560 if you cut grass and no brush thicker than 1". RCF2072 weighs 745 pounds.
The addition of a 600 pound CAB and liquid filled rear tires to an L3560 would moderate my assessment, especially if you need to mow hills.


Rotary Mowers, like other implements, come in Light Duty, Medium Duty and Heavy Duty models. Generally speaking, there is 150 pounds of weight difference assoicoated with heavier increments. If you carefully study new mower specs, most have Category 3 drive lines. Heavy Duty models have Category 4 drive lines. Dealers often refer to HD Category 4 mowers as "Right-of-Way" Mowers.

L3560 has 37-horsepower gross, 35-horsepower net.


25 horsepower will power a Light Duty 5' Rotary Mower
35 horsepower will power a Heavy Duty 5' Rotary Mower

35 horsepower will power a Light Duty 6' Rotary Mower
45 horsepower will power a Heavy Duty 6' Rotary Mower

Using a HD Rotary Cutter of 1,000 - 1,100 pounds you will need an FEL to hold down the front of the tractor on moderate slopes.

I use a Land Pride RCR2660 (60") HD Rotary Cutter with a Class 4 driveline, weighing 1,002 pounds. My 2013 vintage L3560 powers RCR2660 through Florida jungle mowing over flat land with no complaint and no damage/distortion to the implement. I "try" not to cut brush thicker than 1-1/2". $3,120.00 in May 2018.

I had a Land Pride RCF2060 (60") medium-duty Rotary Cuter with a Class 3 driveline, weighing 620 pounds, nominally rated for 2" brush. It required a ~~$600 repair each year when I would get into brush. It would have been reliable cutting grass. $1,600 in February 2014.

Most Rotary Cutter mowing is done in HST/MEDIUM, with HST/PLUS half-step shifts.

If you buy too light a Rotary Cutter, then cut saplings, it will soon visit the shop.

 

[Hay Dude]

HAY DUDE:

"There is so much more to trying to size a mower correctly. Its not just charts and graphs.

My point is, grass thickness/density/crop type, whatever you want to call it, is so important. If you only cut 1-2 times per year, it will be thick and heavy requiring more power. If you cut same field 4-6 times per year, less HP and a wider mowing deck may be possible."


Russman16 said:

"I will be bushhoging 12-13 acres of the field once a year or once every 2 years. My intentions are to let the field grow up some for deer and rabbit hunting. I will keep the other few acres either mowed down monthly or in food plots.

I want something that'll pull a 5' bushhog easily with only being mowed once a year or every other year. And maybe a 4' bushhog would be fine, just don't know how long either would take me to mow."

Here is a mowing calculator. Mowing once per year will require a tractor speed of around 4-mph. Mowing every second year will limit tractor speed to 3-mph due to density of vegetation.

Mowing once per year will require 40 - 45 tractor horsepower to operate a 60" HD bush hog = 2 acres per hour.

Mowing once per year will require at least 50 tractor horsepower to operate a 72" HD bush hog = 2-1/2 acres per hour.

Allowing for a 6" overlap, a 48" bushhog mows only 42" per swathe. Ugh!

Mowing Calcuator | How many acres can I mow in an hour

www.landscapecalculator.com

I appreciate all the effort you are putting into this. However, I would say that a ”mowing calculator” is at best, just a rough guide. Anyone who owns or maintains land will know their hills, crop density, #of mowings, rainfall, etc. and need to throw all that into the mix to decide the best set up for their individual needs.

 

[LD1]

Its a crazy notion to think that you need a 45hp tractor for a 5' mower. And 50hp for a 6' mower.

Mower size and tractor HP are only TWO of the THREE pieces of the puzzle. The third being speed.

Back when everything was geared tractors, and 3mph was about the slowest you could go....it was a little more straight-forward. Because if you constantly bogged down in 1st gear your cutter was too big.

Now we have gear tractors that have the first 3 or 4 gears UNDER 3MPH.....and most having a 1st gear under 1MPH.....or even better yet.....HST transmissions. SO you can go as slow as you need to.

Fun fact.....3MPH with an 8' cutter will do ~2.5 acres per hour. To get that done with a 5' cutter you need to go 5 MPH. Running a bigger cutter at a slower speed doesnt require any more power. But it sure does offer a much smoother ride.

Which is why I opt for an 8' cutter on my 50hp (42 PTO) tractor that you would suggest needs a 5' or 6' cutter.

And the ONLY thing preventing me from pulling a 10' cutter is the fact that I trailer ALOT and dont want to deal with a wide load permit to haul a 10' wide cutter.

Most all of the properties that I mow more than once a year I do so at ~7mph and dont struggle one bit in the power department. And even mowing dense crap for the first time in a few years....its rare to have to drop below 4mph.

90% of the time I have to reduce speed is NOT because of lacking power. ITs because of terrain (rough field), unknown areas, obstacles, etc. So why in the world would I want to drop to a 5 or 6' cutter.

My old mow rig was a 34hp (29pto) gear tractor with a 6' / 1000# cutter. (too big according to you). However I never struggled and routinely mowed in H1 or H2 gears (4-5.5mph). And the only reason I didnt mow in H3 was because it was a big jump to like 8.5mph....which cut quality suffered with the low 10.2k blade speed and a much rougher ride.

Some of your advice is sound.....but when it comes to sizing a rotary cutter.....you sound too much like the tractor/implement manufactures. WAY too conservative....which turns into very under-productive.

 

[jeff9366]

Anyone who owns or maintains land will know their hills, crop density, #of mowings, rainfall, etc. and need to throw all that into the mix to decide the best set up for their individual needs.

Indubitably.

 

[sunandsand]

Mowing about 60 acres of grass, light brush, weeds, a few pine saplings using a Kubota 2601 HST and a 5' bush hog. Works fine, I use medium speed, once a year or so. (Land will be developed eventually.)

Only problem is when I hit cogon grass . . . it is like trying to mow steel wool. Low range, go REALLY slow, often stop entirely until the bush hog spins up again, then move forward another few inches. Belly mower won't cope with it either, even set to highest height.

Cogon grass is nasty stuff . . .

Mike/Florida

 

[RancherGuy]

Its a crazy notion to think that you need a 45hp tractor for a 5' mower. And 50hp for a 6' mower.

Mower size and tractor HP are only TWO of the THREE pieces of the puzzle. The third being speed.

...

And as 'sunandsand' mentioned, the fourth piece is the type of grass. I have experienced 'watergrass' here in Texas that is really hard to cut.

The fifth piece is the cutting height. If I want to shred small trees or brush, or if I want to shred fall grass in preparation for decay over the winter, I will drop the mower to the absolute lowest position, which may be [much] less than 3 inches high. Then trees remnants will cause no tire issues and will die. But by cutting so low, more power or less speed is required.

The sixth piece is the deck tilt. I have found that for good distribution of cuttings, it is necessary to have the front of the deck slightly lower than the rear. This facilitates a "cut once" process then the cuttings distribute evenly. if the blades are level or front higher than back so both the front and back cut, more power is required and the grass bunches up and is left in clumps. I think it ends up circulating the material around the underside several times before a clump exits.

 

[RancherGuy]

FWIW, contrary to the comments about "what the book says", weight of the tractor or mower has nothing to do with power required or recommended to mow. Additionally, extra rear tire weight does nothing for mowing. If the shredder is on the 3-point arms, then weight is already shifted to the rear tires. If the shredder has its own wheels that stay on the ground, such as a batwing, then the mower already adds weight to the tractor through the hitch. If you need weight for traction, then you are considering conditions such as soft or muddy that are not suitable for mowing.

In the real world, I have a 37hp (engine hp) non-HST tractor with a 6' medium duty shredder-mower that will cut most anything I attack, in terms of heavy grass cutting. This setup will also cut 3" trees if the correct backing-up technique is used - detail not included in this discussion.

In the real world, I have a 5,000 pound, 15 foot HD batwing that works very well with my 65, 100 or 120hp (PTO hp) tractors. Only if the area is extremely thick AND I want to cut less than 5 inches high do I need my 100.

There - you can do the math if you want to calculate hp per foot. If you don't have enough power then the only impact may be that you have to select a slower travel speed, and that speed may fluctuate as you hit different sections - speed up when you can but slow down when necessary. But note that like I mentioned earlier about the "sixth factor": my mowers are set to cut once. Of course there is almost no such thing as too much power - as long as the implement is designed for the job.

 

[Pinzgauer]

I run a 5 foot cutter behind the Farmall C that sports less than 19 horsepower....been doing it for 30 years.

I ran a BH SQ60 behind a Kubota L-185DT for 2 decades. Mostly flat pasture, with brush (privet) hedge clearing.

Never felt I was HP limited. I want to say it was 17 or 19HP. The L-185DT was the same size as the 3 cyls (L-245, etc) so carried the Squealer with no issues. Could cut my pasture in high range 3rd or 4th (top) gear if it had been cut in last month, slowed down to low range top gear if it was high (1-3 ft).

I now use a L-2501HST with a land pride 60". Same deal, though I cut faster on level, and slow down a bit on hills.

To me the most important criteria is can the tractor safely handle the weight of the BH. The Land Pride 60" is much heavier than the BH SQ60 I used to use. Of course, if hilly or getting into tree cutting, or greater than 5' or 6' decks, HP requirements go way up.

 

[MossyDell]

For years I cut heavy pasture grass with a 6' King Kutter and my 33 hp JD970. It did beautifully. Now I sharpened the blades every year and rarely mowed down brush. It was a stout, medium duty cutter. I don't remember my pto power, but thick grass was no problem. Of course I hit the occasional fallen limb, etc.

We got ready to move and I sold my King Kutter, but our realtor told me people loved the look of my grazed and mowed pastures and I needed to keep it up. So I bought a shiny new round-backed Frontier 6' cutter. It was slick looking but the steel wasn't as heavy. Seemed very light duty, but should have been fine for what I planned. After mowing in clean pastures around my house with fairly light growth, its gearbox started leaking.

I'm told Frontier/Deere has improved that product, but I still feel burned and the experience has made me more wary. My cheaper and cruder King Kutter was heavier and better all around than the "better" cutter. Not one problem in 10 years.

 

[SetterDog]

For years I used a 5 foot Howse behind a L210. Achieved results most would call me a liar with.