Pairing Flail Mower Size And Cutting Conditions To Tractor PTO Horsepower

[Cahaba Valley Farm]

Greetings to all of you out there. For the last several months I have been working and researching every day to find an answer to this question: How do you correctly pair a particular size flail mower for a particular type of cutting conditions to a particular tractor's PTO power output? I have gone as far as contacting several tractor dealerships, flail mower manufacturers and even tried asking particular knowledgeable members in the big flail mower thread this question with no satisfactory answer given to date. If there is anyone out there on this forum that knows the answer to this question please comment so the 8th wonder of the world can be solved.

 

[Komrade]

https://www.tractorbynet.com/forums/attachments/118882-lets-talk-flail-mowers.html

 

[3Lfarms]

Simple answer is every mower manufacturer specifies minimum horsepower for each model of mower.

If you are just cutting grass that gets cut frequently, the minimum hp is sufficient. If you are cutting lush, overgrown areas, you want to be closer to the max hp for that mower, unless you want to be moving at a snail’s pace.

Dry grass cuts much easier than green grass, so if you are just knocking down weeds once they dry out, you can move pretty quickly.
I can run my tractor about 8-10 MPH when the grass is dry, but only about 3 MPH when it’s green to still get a nice cut.

 

[CADplans]

Simple answer is every mower manufacturer specifies minimum horsepower for each model of mower.

If you are just cutting grass that gets cut frequently, the minimum hp is sufficient. If you are cutting lush, overgrown areas, you want to be closer to the max hp for that mower, unless you want to be moving at a snail痴 pace.

Dry grass cuts much easier than green grass, so if you are just knocking down weeds once they dry out, you can move pretty quickly.
I can run my tractor about 8-10 MPH when the grass is dry, but only about 3 MPH when it痴 green to still get a nice cut.

I have proven all that "3L" said is correct, by trying my mower in differing fields,, and on 2 different tractors,,

I have used my JD390 flail behind a 41HP tractor, and a ~60HP tractor,,

Thick grass will slow the 41HP tractor to a crawl,,
the ~60hp tractor will test the adjustment of the flail mowers belt drive,, smoking the belt if the belt is slightly loose,,, :laughing:

Too much HP is WAY easier to live with,, compared to too little,,,

 

[davrow]

Also, nothing says you have to cut the full width of the mower (usually).

I have a smaller tractor (25 PTO HP) and need to cut brush taller than the hood of my tractor (the flag is 6').



I bought a 48" flail mower. I still have to go very slow and only cut 24" per pass.

Works great because I am retired and only cut 3 acres. Not many would consider the rate I cut at acceptable for their needs, I think.

 

[Stan B]

I think another variable here is shuttle vs HST. I have a 55" offset ditch/bank flail behind my ~30 PTO HP Kioti CK3510 HST, and I think I should have gone wider for more "reach". It has never bogged it down even occasionally chewing through 1.5" saplings and autumn olives, but because I'm mowing on the edge of a slope, I go very slow. With an HST, the travel speed is independent of PTO/engine RPM. I can peg the engine RPM and just crawl, pause, or move more quickly when I want without dropping PTO revs. I know technically the HST trans reduces available PTO HP, but for my application, I feel that it makes the HP delivered to the implement more effective.

 

[Cahaba Valley Farm]

I have proven all that "3L" said is correct, by trying my mower in differing fields,, and on 2 different tractors,,

I have used my JD390 flail behind a 41HP tractor, and a ~60HP tractor,,

Thick grass will slow the 41HP tractor to a crawl,,
the ~60hp tractor will test the adjustment of the flail mowers belt drive,, smoking the belt if the belt is slightly loose,,, :laughing:

Too much HP is WAY easier to live with,, compared to too little,,,

I have proven all that "3L" said is correct, by trying my mower in differing fields,, and on 2 different tractors,,

I have used my JD390 flail behind a 41HP tractor, and a ~60HP tractor,,

Thick grass will slow the 41HP tractor to a crawl,,
the ~60hp tractor will test the adjustment of the flail mowers belt drive,, smoking the belt if the belt is slightly loose,,, :laughing:

Too much HP is WAY easier to live with,, compared to too little,,,

Hey CADplans, nice to see you again.

Ok this really helps me a lot. I think I am on to something here. So I looked up both of your tractors on TractorData here: TractorData.com John Deere 415 tractor information and here: TractorData.com International Harvester 584 tractor information
and then found a inches to decimal of a foot calculator here: http://http://kellypipe.com/common-pipe-industry-tools-specifications-calculators/tools-inches-to-decimals-of-a-foot-calculator/ When I ran the calculations I found that your John Deere 4105 is only a little over 4HP per foot but your IH 584 is exactly 7HP per foot. Are you implying that the IH 584 is overkill for your 390 and vegetation density?

 

[CADplans]

Are you implying that the IH 584 is overkill for your 390 and vegetation density?

The 584 is not overkill,, some people would actually want more HP per foot than the 584 delivers,,

for me, the 584 is adequate,, the 4105,, well, the JD390 will never be connected to the 4105 again,,,

BUT, the 4105 does a perfect job of mowing grass,,,

 

[Cahaba Valley Farm]

The 584 is not overkill,, some people would actually want more HP per foot than the 584 delivers,,

Can you give me some reasons why they would want more HP per foot?

for me, the 584 is adequate,, the 4105,, well, the JD390 will never be connected to the 4105 again,,,

BUT, the 4105 does a perfect job of mowing grass,,,

It does a perfect job of mowing grass with your 390 or your finish mower that you have pictured above?

 

[Industrial Toys]

A bigger tractor can just smoke the belts off a struggling flail mower, whereas a smaller machine might bog down. I hated running my 917 Ford on my JD6200. Felt like it was a real waste of fuel and tractor hours. Also, for some unknown reason, the bigger tractor would bust the mounting "Y" frame on the mower.