Rotary Cutter Bush hog hp requirements

[dennis5150]

Is there a general rule for how much pto hp is needed for various sizes of bush hog type rotary mowers? I will be needing to cut tall (2-3ft) grass hay, lots of blackberry bushes , small diameter saplings. Am I going to need at least 25hp, or will 18 to 20 work? Any advice is appreciated.

 

[Deerlope]

The rule of thumb is 5 HP per foot of cutter. Thus a 5 foot bush hog requires 25 HP.

 

[Gatorboy]

Is there a general rule for how much pto hp is needed for various sizes of bush hog type rotary mowers?

Every rotary cutter should have a minimum PTO-HP spec.

 

[art]

Sometimes the type of terrain requires a larger tractor to hold a mower then the horsepower per foot but that is a good rule in general.

The type of transmission also changes the requirements a bit as a hydro gives more flexibility.

 

[RoyJackson]

You can do it with 18-20 HP. I used a 60" cutter behind a 16 (PTO) HP tractor. But you'll be going slow, which is a good idea if you've never cut the field before.
As far as gear vs. hydro...either works so you mow with what you got.

 

[greg_g]

The rule of thumb is 5 HP per foot of cutter. Thus a 5 foot bush hog requires 25 HP.

Dennis - whereas I agree with Deerlope's rule of thumb, it should be qualified that he's talking 5 PTO horsepower per foot of rotary cutter. Another general rule is to try to get a cutter that is at least as wide as your tire tracks.

//greg//

 

[Farmerford]

Dennis:

Deerlope is correct about the rule of thumb of 5hp/ft. My practical experience indicates that you may be able to get by with a little less if you have a "light duty" mower like the Bush Hog Squealer that uses 3/8" thick blades rather than 1/2" (or even 5/8") thick blades like the medium and heavy duty Bush Hogs.

I have both a light duty Bush Hog Squealer 480 (4' with 3/8" thick blades) and a medium duty Bush Hog 285 (5' with 1/2" thick blades). I was surprised when mowing side by side in 3' grass/weeds (an overgrown pasture) that the light duty Squealer on an 18hp (pto) tractor could travel significantly faster than the medium duty 285 on an 29hp(pto) tractor, yet the Squealer had only 4.5hp/ft and the 285 had 5.8hp/ft. I could attribute the difference only to four things: 1. The light duty mower had 3/8" x 3" blades while the medium mower had 1/2 x 4" blades; 2. the light duty blades were "flat" with no wing to create an uplift while the medium duty blades had the wing at the back of the blade ends; 3. the light duty mower had a 40hp gearbox while the medium duty had a 70hp gearbox, which probably had slightly more friction losses; and 4. with a 6" overlap on the prior cut, the actual cutting widths were 3 1/2ft and 4 1/2 ft, which changes the hp/cut ratio to 5.14 and 6.44, respectively.

If there is a lesson in my experience it is that there are disadvantages (in addition to higher cost) in buying a heavier duty mower than is required. The light duty Squealer is rated for 1" brush, but I have used it on 2" softwoods for years and it seems to have suffered no damage. If your saplings are no larger than 2" softwood (pine, etc.) or 1 1/2" hardwood (oak, etc.), consider a "light duty" mower like the Bush Hog Squealer. You will save on the original cost, it will cut hay, grass, etc. faster than the heavier machine, and you can use a smaller tractor.

 

[jbrumberg]

dennis5150:

Welcome to TBN ! Deerlope is stating the general "Rule of Thumb". I read somehere that light duty rotary cutters require 2 HP per foot and heavy duty RC's require 5 HP and that a HD unit could take on 2" diameter saplings (I am assuming soft woods.). I have no current problems going through 7A's of vegetation like yours including cutting up weeds 5' -6' and the occassional +1.5" softwood sapling with my 60" MD RC powered with 23+HP PTO. I also cut the same area with a lot more poplar sapling in the 2'' range with a 40" HD RC powered with 11HP PTO with my old tractor (It would stall out on occassion.). What you can cut also depends on whether or not your RC is light, medium, or heavy duty with the respective upgrades in metal, gear boxes, and weight with corrsponding upgrades in HP. Jay

 

[Z-Michigan]

The rule of thumb is 5 HP per foot of cutter. Thus a 5 foot bush hog requires 25 HP.

Based on my experience to date I think this is a good rule of thumb. I have 8 PTO hp per foot (6 ft cutter and 47 PTO hp) and I find that this setup is massively overpowered.

 

[dweitzel]

I find that this setup is massively overpowered.

Yea, maybe, but isn't it somewhat satisfying just knowing that you can back that thing over just about anything and grind the he** out of it?

Sometimes I just like to "see" if I can cut it up rather than digging it out. Ok, testosterone out of my system now.

dw

 

[RollingsFarms]

Based on my experience to date I think this is a good rule of thumb. I have 8 PTO hp per foot (6 ft cutter and 47 PTO hp) and I find that this setup is massively overpowered.

i'm strongly considering this same setup with my next tractor purchase. i think i'm gonna buy a medium duty cutter. have you ran into any problems with your setup as it is?

 

[Z-Michigan]

I have run into 0 problems since I got my LX6 corrected (the blade pan had been damaged somewhere in shipment, but with help from TBN I noted this before ever using it and got it fixed under warranty).

I think an MX6 or Woods equivalent would be a good match. Also, a 7' lift cutter or 8' pull type cutter should be fully within the 5105 capabilities if you want something larger. I have the horsepower to mow at 10mph in 6th gear. Unfortunately this bounces me out of my seat and doesn't do much in the way of effective work. YMMV.

 

[john_bud]

Based on my experience to date I think this is a good rule of thumb. I have 8 PTO hp per foot (6 ft cutter and 47 PTO hp) and I find that this setup is massively overpowered.

Obviously, you need to cut bigger stuff....

jb

 

[dennis5150]

Thanks for all the great advice. Now I will have some good background before I get to the dealer.
Dennis

 

[JerryG]

The type of transmission also changes the requirements a bit as a hydro gives more flexibility.

And needs more HP.

 

[JerryG]

It needs 5 PTO hp or more per foot. There are many variables. 5 HP doesn't do a good job with the type of mowing that I do even though I know that it would for many.

 

[Farmwithjunk]

The 5hp per ft rule of thumb is more or less a minimum requirement. Take in to consideration what conditions you're mowing in. Hills? Heavy grass/weeds? Brush? I mow with 40hp/6' 47hp/6', 60hp/7', and 95hp/15'.(all pto hp's) All 4 have seen conditions where they meet there match. In MOST conditions they cruise effortlessly. Over-kill is better than underpowered. You don't have to use every speck of power a tractor produces, but not enough power is hard to overcome.

HP relates to physical size of the tractor to a certain degree. An often overlooked aspect is how a tractor handles the weight of a certain mower. Heavy duty mowers are usually HEAVY....Comparable width requires bigger tractor (hence "more power") from light duty to heavy duty.

 

[flusher]

Is there a general rule for how much pto hp is needed for various sizes of bush hog type rotary mowers? I will be needing to cut tall (2-3ft) grass hay, lots of blackberry bushes , small diameter saplings. Am I going to need at least 25hp, or will 18 to 20 work? Any advice is appreciated.

I have a Kubota B7510HST (21 hp engine, 17 hp pto) and a 4-ft King Kutter hog for my 7-8 acres of weeds on my 10-acre parcel. It handles 3 ft weeds OK if I mow slow in low gear (about an hour per acre). Don't have blackberry bushes or saplings so I can't help you there.

 

[DaNag]

My experience, while far less than many here, is the "5HP/FT" rule of thumb is pretty meaningless out of context. I'm running a 72" behind my 3130HST, and it works just fine. At 24 PTO HP, that's only 4HP/FT.

That being said...I've got little more than rough field grass/weeds to mow. The brush I do have is pretty small - rarely more than 1.5". I also never mow when wet. In these conditions, even on hills, I can easily cut through 5' tall material at 5MPH.

Some may consider the above conditions optimal or rare...but for me, and possibly others, they are the norm.

 

[RoyJackson]

How many here have actually bogged down a rotary cutter? I've read tht 5 HP per foot "rule" for quite a while, but have read of few folks that had issues with their cutters.
First year I had my 5' cutter, it was operated behind a 16 PTO HP tractor. That's less the 4 PTO HP per foot. I had no problems...just use common sense when you operate the unit.