Gearing down a PTO shaft

[IVECOKID]

PTO hp is going to stay at 40hp no matter what you do .

 

 

Ste

[gdh]

I know that, my logic was that it would be like putting it in a lower gear.

 

Appreciate all the advice but it looks like a no go.

[Ilnumero]

Tractors are designed to produce max power around 540 pto revs, something like 1700 engine rpm, and all implements are designed to work at 540 pto too, to benefit from the power delivered by the tractor.

 

I'm surprised that a pto-driven implement is designed to operate at 400rpm, and haven't personally seen any implement with that rating before. That means that the tractor will not be running optimally, or fuel-efficiently.

[wisecobandit]

By changing gearing it would effectively change torque.

Think of a 4x4 it produces more torque to the wheels in low ratio box compared to high ratio.

 

Doesn't mean I think its a good idea when it comes to pto tho.

As said, said machines have an rpm rating which should be stuck to for obvious reasons. Also tho as mentioned you don't want to make it the easiest on the tractor as they will glaze up the bores and lose engine power and compression making harder starting etc.

[Tom D]

Most processors run at lower revs because their Hp requirement is so low, its a fuel saving thing. All the ones I have used work in the 400-500rpm range. Its just the lack of HP that the massey has thats the problem. Keep the saw nice and sharp and that will help a little.

[gdh]

Yeah thanks everyone, it's fine how it is and the tractor's not working too hard so best leave it be. It's only ever been a problem cutting 18inch diameter oak and even then it's just a matter of not cutting and splitting at once

[cornish wood burner]

It runs the machine at 420-30 at rest, that's about 2 thirds revs on the tractor. The machine is rated to be used between 400 and 430rpm, any more could overheat the hydraulic motors (and presumably run the chainsaw much too fast).

 

I'm wondering if gearing it down 80% so I can run the tractor on higher revs would increase the power going through the pto from 40 to 48hp or if it would make no difference between the torque would be the same.

The pto hp at say 430rpm would be about 30hp because it's below the engine speed that generates max power. Gearing the pto down would enable you to run at a higher engine speed to generate the rated 40 hp

[richy_B]

Does it need to be movable/a tractor? I'm sure an agri - engineer could knock up a 'donkey-engine' with a PTO on it. I might be dreaming it up but I'm sure I saw a transit van chopped in half and the drive shift welded to a standard shaft powering a processor. I imagine engine running at 1500-2000 rpm, first gear of 3.5:1 odd and you'd be away. HP to spare....

[gdh]

It would be interesting to know if the 40hp requirement takes into account the lower pto speed.

Does it need to be movable/a tractor? I'm sure an agri - engineer could knock up a 'donkey-engine' with a PTO on it. I might be dreaming it up but I'm sure I saw a transit van chopped in half and the drive shift welded to a standard shaft powering a processor. I imagine engine running at 1500-2000 rpm, first gear of 3.5:1 odd and you'd be away. HP to spare....

Unfortunately we use the tractor to drag it around. Something to look into if we ever go bigger though.

[cornish wood burner]

It would be interesting to know if the 40hp requirement takes into account the lower pto speed.

 

Unfortunately we use the tractor to drag it around. Something to look into if we ever go bigger though.

Almost certainly the hp requirement is at a certain rpm. 430 in this case.