90hp tractor 5ft rotary mower

[im4tractors]

Hi there, I am relatively new to tractors and farming. I am currently running a Kubota M9000 90ish HP and I have an old 5ft rotary mower. The pto shaft is shot, parts are as expensive as a new one. I suppose I have a 2 part question.

Am I ok to run the smaller rotary on my kubota? I use it mainly to keep ahead of sapplings (mostly less than 1" diameter". Assuming so, does the new pto shaft need to be a series match for my tractor hp?

Thanks,

 

[oosik]

I would say that 90hp is probably more than the manufacturer hoped you would be using. However - used with due diligence and care - you can probably get by OK.

If you purchase a new PTO shaft - yes, you definitely want it to be capable of handling your tractor hp output.

And - welcome to TBN.

 

[ericm979]

Your tractor is a lot wider than the mower so you will be sometimes mowing ground that you just drove over. That will smash down the vegetation which means it may not mow as well. A 5' mower probably has a 40hp gearbox or thereabout. So you can destroy it if you really abuse it.

You can get PTO shafts at Tractor Supply or Agri-Supply. You need to get one with the correct end for the mower, the correct end for the tractor (likely 1 3/8" 6 spline but check), the right strength to handle the power (the series), and long enough. You will probably have to shorten the shaft. It's not hard, there are youtube videos showing how to do it. The existing shaft has a shear bolt or a slip clutch. Your new shaft should have the same thing. Those are there to protect the tractor if you hit something large and immoveable with the mower.

 

[newbury]

Yes, get a shaft that will handle your HP. Protect your mower with shear pins or a clutch.
A shaft for that size mower with a low hp tractor would be cheaper but could bend like soft spaghetti.
I've bent one.

 

[oosik]

I've always wondered about this implement width obsession. How do you NOT drive over the grass first - before mowing it. Unless you want to do all your mowing in reverse. OR - have some sort of mower on your FEL.

 

[TerryR]

I've always wondered about this implement width obsession. How do you NOT drive over the grass first - before mowing it.

Good point. That's a major reason why I got an offset mower, in my case a ditch and bank flail. My rotary did an awful job because it couldn't cut the weeds the tractor had run over and they popped back up half an hour later.

 

[loggin]

I've always wondered about this implement width obsession. How do you NOT drive over the grass first - before mowing it. Unless you want to do all your mowing in reverse. OR - have some sort of mower on your FEL.

I didn't quite understand that either.. What I do understand is that you cannot get close to a fence or an obstructed edge when the mower is narrower than the tread, unless it's offset..

 

[ericm979]

I've always wondered about this implement width obsession. How do you NOT drive over the grass first - before mowing it. Unless you want to do all your mowing in reverse. OR - have some sort of mower on your FEL.

You're right. I should have said that you'll run over the stuff you want to mow twice instead of once.

 

[scootr]

With an offset mower you have only one wheel in the uncut grass vs 2. Unless you have a mower on the front of the thractor you just have to live with a wheel in the cut. I use a 7ft offset flail which sticks out on 1 side allowing me to get as close to the fence or tree or creek as I dare.
Last yr I rehabbed and modified a 5ft BH mower for rough cutting. It was free and the modification was a low cost experiment. If the tires leave the dreaded stand up rows I'll just have to move over a bit and cut it twice make a 4.5 ft cut.

 

[Vigo327]

If you have a functional slip clutch or shear pin setup on the mower end of things, the pto shaft doesn't really need to stand up to the tractor's full HP potential. However, a broken driveshaft slamming around is one of the most destructive forces in the vehicle world, so it's highly likely the cost to buy a stronger pto shaft suited to your HP level could just be considered 'cheap insurance'.