Rear Finish Mower Exceeding max HP rating for finish mower

[UncleBuck1]

Okay, I should know the answer to this, but I don't.

I'm looking to purchase a used finish/grooming mower and all of the ones that I'm finding have a fairly low max HP ratings- for example, the manual for one Land Pride mower I looked at said "the horse power rating of the tractor should not exceed 35 PTO horse power." The problem is that my tractor is rated at 70 PTO horsepower! It seems that the belt drive is the weak link and would probably prevent any damage from overpowering the gear box.... right?

Bottom line, what sort of problems will I face if I run a finish mower rated for 35 PTO HP on a 70 HP tractor?

Brian

 

[radios1]

you might trash the gearbox, but those are cheap, right?.

 

[ptsg]

I don't think the gearbox will be the problem. Those are usually built for higher HP than the implement is rated to. The belts, on the other hand, are the weak link but it will only slip if you load the blades too much. Like when going to fast through very thick grass.

 

[blackd]

I just can't imagine it being a MAJOR problem. Starting the PTO with engine at idle and then increasing revs to normal PTO speed would not normally stress the mower drive train. Starting the PTO at high revs might. Hitting something while cutting on a over powered mower also MIGHT depending on what was hit. The weakest link is supposed to be in the mower drive train. Right?

I don't see how any of these things would be a major difference due to horse power. A weak mower drive train should break when it hit a hard object regardless of horse power driving it. Over revving it is possible, but unlikely to be a MAJOR problem short of hitting something. My last tractor had a multiple speed PTO, and I could run the finish mower on any of them, but it was less HP than yours.

You could always go to a slip clutch or sheer bolt PTO shaft to solve most of these weaknesses.

 

[Jchonline]

What are you finish mowing with a 70HP tractor? Any concerns about damaging the ground?

 

[bigtiller]

Okay, I should know the answer to this, but I don't.

I'm looking to purchase a used finish/grooming mower and all of the ones that I'm finding have a fairly low max HP ratings- for example, the manual for one Land Pride mower I looked at said "the horse power rating of the tractor should not exceed 35 PTO horse power." The problem is that my tractor is rated at 70 PTO horsepower! It seems that the belt drive is the weak link and would probably prevent any damage from overpowering the gear box.... right?

Bottom line, what sort of problems will I face if I run a finish mower rated for 35 PTO HP on a 70 HP tractor?

Brian

I think you are probable right. Have you priced the cost of a new belt? That might be the deciding factor, some of them get expensive.

 

[radios1]

"the horse power rating of the tractor should not exceed 35 PTO horse power." guess why the manufacturer said that!..

 

[dennis103]

Land Pride makes many that are up to 60 or 70 HP. I'm not sure I would be too worried about the HP rating if you are just finish mowing. Where you might run into a problem is if you were "finish" mowing 12" heavy grass. If you are mowing every week or two it wouldn't matter what tractor HP was as long as its minimum enough to run the mower.

 

[radios1]

if you want a really nice cut, get a reel mower, that's what they use on golf courses. it's like the grass is cut with scissors..

 

[RickB]

You will not have any problems if you cut grass that has grown to a reasonable height and do not hit any solid objects with the blades. Belt drive is your friend.

 

[UncleBuck1]

Thanks for all the information!

 

[JimR]

Okay, I should know the answer to this, but I don't.

I'm looking to purchase a used finish/grooming mower and all of the ones that I'm finding have a fairly low max HP ratings- for example, the manual for one Land Pride mower I looked at said "the horse power rating of the tractor should not exceed 35 PTO horse power." The problem is that my tractor is rated at 70 PTO horsepower! It seems that the belt drive is the weak link and would probably prevent any damage from overpowering the gear box.... right?

Bottom line, what sort of problems will I face if I run a finish mower rated for 35 PTO HP on a 70 HP tractor?

Brian

I have a 7 foot Landpride that is belt driven. The belt slips when you get into too much grass and going too fast. You will learn how fast to mow quickly. I had this on a 27HP tractor previously and the rpms would go down if working too hard. You will not have that issue with a 70hp machine. You will hear the mower change tones when bogging down and the belt will slip. It is better for the belt to slip than it is to destroy a gearbox. I have had this mower for quite a few years and have never done anything to the gearbox. For 5 years I was mowing about 12 acres with it. Now I only do about 5 -6.

 

[kthompson]

With tractors and implements the odds of having exact match of hp rating is slim. I have run a 6 foot bush hog finishing mower many hours with my 68 hp tractor and also with my 27 hp tractor. If you are running correct pto speed the only danger is as has been said trying to cut too heavy a load or too fast speed.

If you use common sense and pay attention you can tell when a tractor is being over loaded or the implement is being pushed beyond it's design.

 

[4570Man]

If you use your brain and don’t over do it you’ll be fine. The belts will slip with a brief overload.

 

[Texasmark]

2:1 over rating is quite a distance. V belts can help to cushion a shock but there is a limit there. A suitable disconnect device would surely be in the offering...ensuring that it is functioning properly. I have BTDT on tearing up a gearbox on a gear driven shredder when high centered on a levee....8' dual blade popular brand, protective devices intact, but being dual blade, was the downfall.

 

[CADplans]

My SIL breaks 2 or 3 finish mower belts per year,, and he is within the horsepower spec with the tractor/mower,,
He even orders OEM belts, because they last "longer", but, he simply mows too fast.

he has been doing that for 3 years, and 2 different Woods finish mowers.

So, I say the belt will fail if you push the speed of mowing.

 

[Slowpoke Slim]

I personally wouldn't want to run a 70 hp tractor over any grass area I cared enough about to use a finish mower on.

Out in a pasture or road ditch, etc, sure. But a 70 hp tractor carries enough weight that you'd be more likely to rut up your ground just by driving it over the surface. I don't even like to drive my 7000 lb tractor over my lawn. And if it's not "lawn", there's no reason at all to cut it with a finish mower.

 

[RickB]

Farmers make hay on smooth well cared for fields with tractors far bigger than 70 hp. If the soil is not wet and you do not drive like an idiot a 70 hp tractor will not damage sod. Condemning the use of a tractor of that size without considering tire style and contact patch is just blowing smoke.

 

[3gunr]

i agree with rickb tire type might do more damage than weight.

 

[kthompson]

I have a M6800 Kubota with loaded rear tires and cast iron rims for tillage on farm. I used it for at least two years mowing our basically new lawn with a 6 foot Bush Hog rear finishing mower. Doubt you would have realize that tractor had been in our yard any time it ever was. The only time it or my larger JD 5525 with cab, loader and filled rear tires ever marked any lawn (mine, my in laws and some others) was when they were wet. I have really left ruts with the JD removing hurricane down trees following say 15 inches of rain. Of course soil type matters and boy does the operator matter. Taking tight turns the front tires can tear a lawn to pieces. The tires are R 1.

Some things that will kill the belts are:
Not keeping the pulleys greased and spindles need a lot. Friend who has tractor garage said people just don't grease the spindles too much..
Improper belt tension.
Not running high enough pto speed.
Cutting too low.
Too fast travel speed.
Dull blades.
Yes cutting material a finish mower is not designed for.