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  1. #1
    Silver Member
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    Sep 2004
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    JD2520/Kubota KX008/ Argo Bigfoot 6x6

    Default Minimum PTO hp

    What are some opinions on the minimum PTO hp to use a 72" RFM and a 60" rotary cutter? Moderate slope on the lawn and mostly over grown weeds for the bush hog.

  2. #2
    Super Star Member RoyJackson's Avatar
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    Bethel, Vermont
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    John Deere 4400 MFWD, Deere 855D UTV, Z920A Zero Turn Mower and assorted implements

    Default Re: Minimum PTO hp

    As a comparison, I did quite well using a 16.5 PTO HP Deere 670 running a 60" RFM and a 60" cutter.
    For a 72" RFM, 20 PTO HP would work...same with a 60" cutter (Land Pride recommends 20 HP @ the PTO as their minimum).

  3. #3
    Super Member Bob_Skurka's Avatar
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    Default Re: Minimum PTO hp

    I don't really agree or disagree with Roy, but I do want to throw out a disclaimer that can both confirm his statements and call them to quesiton.

    My disclaimer is this. We each have different soil conditions and turf conditions. That being said, I have seen on my property that I have totally different conditions in my valley than I have up on the top of my ridgeline. The grass in my valley, if allowed to grow just a bit too long, can easily choke my 60" MMM on a tractor with 18.5 PTO HP. That grass is very thick and lush and while the soil is clay, it is a black clay soil which seems to be fairly rich. The soil on my upper ridge line is a hard tan color which barely supports any plants and what grass that grows up there is sparce and even if it is 10" tall the MMM easily breezes through it without any laboring. I've been to many parts of nation and seen the course gasses of Florida, and the sparce grasses of northern Wisconsin, Michigan and Minnesota and can't imagine ever having those grasses slow down a mower deck. So I generally recommend about 3 to 5 PTO HP for each foot of Finish Mower and 4 to 5 PTO HP for each foot of Rotary Cutter. Bear in mind you have to assess your conditions. If you have thick lush grasses, then go to the upper end of the power requirement scale. If you have space grass, then go to the lower end of the scales. For rotary cutters, if you have a light duty cutter, you could probably go down to something less than 4 PTO HP per food of deck, but only if you are only cutting grasses. I tend to be a bit on the conservative side, but I don't like to bog down my machines any more often than necessary.

    JMHO. For a 72" RFM & 60" rotary cutter, I would want about 28 to 30 engine hp.


  4. #4
    Epic Contributor Soundguy's Avatar
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    Default Re: Minimum PTO hp

    Good info from Bob.

    As a comparison.. a 5' rotary mower runs fine on an old Ford N series tractor in average condition... Ford N were about 26/27 hp new... etc.

    Soundguy

  5. #5

    Default Re: Minimum PTO hp

    I have used a 5ft hog and a 6ft finish mower behind a JD750 (gear 22hp?), a 8N (gear 26hp) and my current Mahindra 2615 (hst 26hp). The gear tractor would handle the mowers but it was a bit of a PITA to keep the tractor in the optimum gear. These mowers are about perfect on the 2615. The hst makes the difference. I can easily and quickly match my forward speed to the load on the mower.

    So my answer, 26hp motor with a hst is a good fit for a 5ft hog and a 6ft finish mower, regardless of grass conditions.

  6. #6
    Veteran Member deerefan's Avatar
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    louisiana
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    1952 8N, 2005 JD 5103

    Default Re: Minimum PTO hp

    where i live bahia is the dominant grass...i was using my 52 8n w/ a 6ft king cutter finish mower. with the grass about 5 inches tall, the 8n, even with a fresh restore and rebuild, struggled. I ended up parking the finish mower and went to my 4ft bushhog. I really solved the problem Saturday and bought a John Deere 5103 w/ a 6ft bushhog so i think power will no longer be an issue. in my opinion, a minimum of 25pto horsepower will give you the power and effeciency you would need for a 6 ft mower.

  7. #7
    Silver Member
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    South Carolina
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    Case-IH DX35

    Default Re: Minimum PTO hp

    Rule of thumb is 5 pto hp for each foot of rotary cutter. Thus 25 pto hp for a 5' bush hog type mower.

  8. #8
    Veteran Member buckeyefarmer's Avatar
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    MD
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    Kubota L3940 L5030 MF205-4

    Default Re: Minimum PTO hp

    I used a 5' mower on 20 HP tractor, no problem. Had many 2-3 yr old locust trees that I cut. wish I could find a picture...

  9. #9
    Platinum Member
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    Sumter, SC
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    Massey Ferguson 5609, Kubota GS1800, eXmark LazerZ XP

    Default Re: Minimum PTO hp

    As folks are fond of saying, your results may vary with your purpose. We used a 28 PTO hp for a 5' bushhog and could not get the cut we wanted in our fields. We were cutting the grass (coastal bermuda mixed with bahia) at 4" to 5" every couple of weeks. Anytime we hit a very thick, dense, tall bit of a grass, we would have to drop down to 1 or 2 low and probably make 2 passes (sometimes more) over the area.

    This was with a new bush hog with new blades. The problem was the cut grass would get 'trapped' under the bush hog and bog things down. It wasn't too bad when we were suffering from a drought, but once we started getting rain and our pastures started growing, it became a big issue.

    Now we have a 62 PTO hp tractor and an 8' brush whacker. One reason for the 8' was because our gates are only 10' wide. Another was so that we would have a bit of extra horsepower for the thick grass.

    I'm a big fan of the one pass, haul arse adage. I don't want to have to come back to get the grass where I want it. From my experience tall, dense grass will put more of a strain on your machine then thicker, yet more sparsely populated woody plants.

    5 PTO hp is a good rule of thumb, but remember YMMV (your mileage may vary).

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