Mowing What size Brush hog

[DAonly]

Hi fellas---- Don't believe I've ever posted here before.

I have a 2010 McCormick CT36HST tractor .......38.5 hp Mitsubishi 4 cyl. diesel. In case you missed the model its a Hydrostatic tranny. Bought it new. I'm wanting to buy a brush hog, but because it's a hydro tranny and I lose a good bit of pto hp because of it, what size brush hog will it handle ..... a 5' or a 6'? Not wanting to cut down big saplings and such but more of high weeds and such in old hayfields.
One dealer says it'll handle a 6 footer, but from what I read the pto only puts out 29 hp.

Thanks in advance for any input!

 

[flewism]

My 5 ft rotary cutter manual states 25 hp minimum at the PTO.

 

[nybirdman]

I run a 5'on our 30 h.p tractor and a 6' on a 44 h.p tractor ;both medium duty cutters.With the bigger tractor and BH in very thick heavy grass(6'+) it will bog down the tractor.I would stay with a 5' in your case.

 

[CobyRupert]

All other things being equal (and keeping it simple)

A 6 footer traveling at 5/6 the speed of a 5 footer uses the same power as the 5 footer.

A 5 footer traveling at 6/5th (120%) the speed of a 6 footer uses the same power as the 6 footer.

That is, it takes "x" amount of energy to cut an acre. How quickly you do it (either by ground speed or width of cut, or both) determines how much power is required.

Can tractor physically handle (lift, not get tippy, etc..) both cutters?

 

[jeff9366]

Better a five foot 900-1,000 pound heavy duty model than a 600 pound light-medium duty model.

I put 300 engine hours on my tractor annually. I needed a five foot medium duty (Category 3 drive line) Rotary Cutter overhauled annually at $600 per.

My current five foot 1,006 pound (Category 4 drive line) Land Pride (brand) RCR2660 (model) Rotary Cutter cuts everything to 2" without slowing. Blades are 1" thick by 4" broad = tremendous strength and inertia.

My tractor has 37-gross horsepower.


LINK: https://www.landpride.com/ari/attach/lp/public/specs/312-783s.pdf

 

[Threepoint]

All other things being equal (and keeping it simple)

A 6 footer traveling at 5/6 the speed of a 5 footer uses the same power as the 5 footer.

A 5 footer traveling at 6/5th (120%) the speed of a 6 footer uses the same power as the 6 footer.

Can tractor physically handle (lift, not get tippy, etc..) both cutters?

Coby, curious how you are calculating this. Simple ratio of cutting width to traveled speed, with all other variables remaining identical? If so, I hadn't thought of it that way. Not sure about that approach. Won't other factors change with the increase in cutting width, e.g. implement weight, maybe gearbox size, friction coefficients... :scratchchin:

 

[DAonly]

For what it's worth, I forgot to mention that the rear tires are almost 6 foot from one to the other......if I get a 5 footer I'd have to overlap my cuts which isn't any big deal I guess......I'd hate to buy a 6 footer and find the pto hp is underpowered.
I've had a 6' Bush Hog finish mower that I've used for 15 years that's done a decent job but not good for real high or too thick of growth. Had to give up my Old '56 Ford 640 series tractor that I restored as the body couldn't take any more abuse. Much easier operating this McCormick Hydro with power steering no less! Plus it's got a front end loader and 4wd.
Some good information here from what I've read.

 

[CobyRupert]

Coby, curious how you are calculating this. Simple ratio of cutting width to traveled speed, with all other variables remaining identical? If so, I hadn't thought of it that way. Not sure about that approach. Won't other factors change with the increase in cutting width, e.g. implement weight, maybe gearbox size, friction coefficients... :scratchchin:

Within limits, (keeping it simple)
It takes a certain amount of total energy to cut a given area. No matter if you do it quickly or slowly.
Power is a measure of how fast you can apply that energy (to reach that total).

So at a constant (horse) power output over a set amount of time the energy you can apply (and area you can cut) is fixed/limited (it is what it is). (That is, it doesn't matter if your going faster with a narrow cutter, or slower with a wide cutter, at the same constant horsepower output, the area cut (i.e. the total energy output) will be the same).

You can think of it in a lot of different ways, but horsepower required is a function of how quickly do you want to cut a given area.

Just like riding a 10 speed bike up a hill. It will take double the (horse) power to do it in 2 minutes versus 4 minutes, but both riders spent the same amount of total energy to get to the top of the hill.

(As an aside: If you do it in 2 minutes in low gear you need a lot of rpms and a little torque, if you also do it in 2 minutes, but in high gear you need a lot of torque, little rpms. Here, there's the same amount of energy and power output in both cases. (but now we're into torque curves, optimum rpm's, and engine's limits on rpm and torque, etc...))

Yes, in reality, implement weight, and gearbox differences, gearing of the tractor, even the torque of a 5' blade versus a 6' blade comes into play, but these variables are probably insignificant compared to the variables of the grass/brush your cutting and the speed you're traveling.

 

[CobyRupert]

A 5' wide cutter behind a 6' wide tractor is mowing 1 knocked down tire track of grass (from the previous pass).
A 6' wide cutter behind a 6' wide tractor is mowing 2 knocked down tire tracks.
Other differences is when you want to mow next to a fence or building.

 

[Turbys_1700]

Your tractor has a 65" wheel base and weighs 2711#. I had a 1720 New Holland that had the exact same wheel base and weighed 2800#. With the rears loaded she was around 3300#. The AG rear tires were set to 60". Your tractor will handle a light 6 foot cutter but you will need ballast on the front. Keep the weight of the cutter under 800#. Anything over that and you will get light in the front. I know from experience.

 

[DAonly]

Your tractor has a 65" wheel base and weighs 2711#. I had a 1720 New Holland that had the exact same wheel base and weighed 2800#. With the rears loaded she was around 3300#. The AG rear tires were set to 60". Your tractor will handle a light 6 foot cutter but you will need ballast on the front. Keep the weight of the cutter under 800#. Anything over that and you will get light in the front. I know from experience.

Yeah, lol, I screwed up! I guess I forgot how to read a tape measure! My rear tires are just a shade over 5 foot. I just measured the tires awhile ago to see how a 5 foot brush hog would sit to them. I see what you mean about mowing alongside a fence or shed......
My rear tires are filled with Beet Juice........front end loader could be the ballast. I won't be beating the machine into submission.......

 

[HEC]

I have run a 5ft. med. duty landpride on my B2650 with about 20 pto Hp. on light to med. duty hay with no problem , never tried it in heavy stuff but would imagine it would have a hard time . I would want something to at least cover my tracks but a 6 footer might be just a bit much in heavy hay even . I run a 6 footer on my M5700 which has about 52 pto hp if I remember correctly and it will take all of it in some instances of heavy hay on a slight incline etc. but than again it is all about the travel speed .

 

[DAonly]

Well Thanks for all of the replies! Looks like the 5' is the general agreement on the size to go with. Now it's just a matter of which brand....

 

[Threepoint]

Within limits, (keeping it simple)
It takes a certain amount of total energy to cut a given area. No matter if you do it quickly or slowly.
Power is a measure of how fast you can apply that energy (to reach that total).

So at a constant (horse) power output over a set amount of time the energy you can apply (and area you can cut) is fixed/limited (it is what it is). (That is, it doesn't matter if your going faster with a narrow cutter, or slower with a wide cutter, at the same constant horsepower output, the area cut (i.e. the total energy output) will be the same).

You can think of it in a lot of different ways, but horsepower required is a function of how quickly do you want to cut a given area.

Just like riding a 10 speed bike up a hill. It will take double the (horse) power to do it in 2 minutes versus 4 minutes, but both riders spent the same amount of total energy to get to the top of the hill.

(As an aside: If you do it in 2 minutes in low gear you need a lot of rpms and a little torque, if you also do it in 2 minutes, but in high gear you need a lot of torque, little rpms. Here, there's the same amount of energy and power output in both cases. (but now we're into torque curves, optimum rpm's, and engine's limits on rpm and torque, etc...))

Yes, in reality, implement weight, and gearbox differences, gearing of the tractor, even the torque of a 5' blade versus a 6' blade comes into play, but these variables are probably insignificant compared to the variables of the grass/brush your cutting and the speed you're traveling.

Coby, now aren't we getting a bit far down in the weeds?

Oh, wait... This is a brush cutter thread!

 

[Sawyer Rob]

IF, it was MY tractor and ME buying a rotary cutter for it, I'd buy a 5" Woods Brushbull…

SR

 

[Tennsawdust]

Just remember that you don't have to cut a full 6 feet with it if you run into heavy cuts. I have a medium duty 6 footer and it will bog sometimes even with the 40 hp or so the Ford has (of course I'm also literally climbing a mountain when it does...) Take smaller bites or go slower and it will be fine. The nice thing about your hydro is that you can just ease off the pedal a bit until it clears whatever heavy clump it's trying to eat.

 

[FTG-05]

6' IMO.

With a 6' you can always slow down, cut less (higher height) or overlap to get the cut. In other words, you have more options.

With a 5', you can never make it cut 6'. You have far less options, other than just speed up.

I'd rather have to slow down for heavy stuff vs. leave unused power on the table for the light stuff. Plus I really hate having to ride right next to the fence line because my bushhog doesn't extend beyond the rear tires.

 

[MikeInEburg]

I would only consider something wider than my tracks, else you'll never mow tight to a fence or other obstacle.

 

[EddieWalker]

Well Thanks for all of the replies! Looks like the 5' is the general agreement on the size to go with. Now it's just a matter of which brand....

I have a 35 hp tractor with 30 hp at the PTO. I run a six foot bush hog and couldn't imagine going with anything smaller. It's wider then the tractor, so I can get closer to the fence line and trees then if I had a 5 foot mower. I try to cut everything on my land twice a year, but sometimes I miss the entire year in some areas and it gets really thick. Then I just go super slow and there really isn't anything that I can't mow if I'm in my lowest gear. I have no problems mowing brush, sapplings and thick grass that is way over the height of my hood.

Usually I'm mowing stuff that's a foot tall or less. Then I just cruise along in mid range, second gear.

Remember that the first time you use it, will be the hardest it will be pushed. After that, if you maintain your place, you will be mowing much shorter material that the larger bush hog can do faster then a smaller. As much fun as it is now, in a few years, it will be another chore that you just want to get done as quickly as possible.

 

[DAonly]

Well thanks again for all the replies! I ended up going with a 5' Bush Hog. Got a decent price on it plus service if I need it. It's only about 2-1/2" inside the outer sidewall of the rear tire on either side ......I can live with that.