Tractor rpm's vs 540/750 pto

[buickanddeere]

Less rpm's to do the job = less work/longer engine life/less fuel.
Same reason you have gears in you car/truck. Higher the gear, lower rpm's, less fuel need.
"As long as you have the hp/torque to do the job in that gear."
If I had a 45 hp tractor and did this, it would be more work for the engine, but I got 30-40 hp just setting there drinking fuel, not doing any work.
And on torque, while I have not seen the specs on this motor, the torque could be close to the same at 1600 and 2100 rpm's.

Less rpm , fewer power stokes means there are fewer power strokes but the pressure, heat and stress is higher . Same HP on shaft at lower rpms means more torque of the shafts, clutch and gears.
If lower rims meant less stress they would have went from 540rpm pto to 250rpm pto instead of 1000rpm pto.

 

[ning]

Going to save thousands of dollars in fuel and tractor wear every day.

I use the OD gear in my truck on the interstate. I could push the button and drive it in 3rd (dating my truck a bit), and it would be doing the same work, but less efficiently. Why not use the OD gear if it doesn't need the lower gear right then?

Do you use your top gear in your truck on the highway? Yeah?

Going to save thousands of dollars in fuel and truck wear every day.

 

[cabinhollow]

Less rpm , fewer power stokes means there are fewer power strokes but the pressure, heat and stress is higher . Same HP on shaft at lower rpms means more torque of the shafts, clutch and gears.
If lower rims meant less stress they would have went from 540rpm pto to 250rpm pto instead of 1000rpm pto.

My tractor has 68-69 pto hp, I needed app 15 hp on the pto today, if I had needed 50+ hp on the pto, yes that would of been more pressure/heat/stress.
About your point on heat, before at 2200 rpm's engine speed to get the 540 rpm pto, after 3-4 hours the heat coming off the tractor overloaded the AC. Today, I had the AC set about as low as it would go.
Also, unless it has been changed, hour meters are set to a rpm. So on this tractor it would be 2200rpm's for one hour to = one hour on the meter. If I run at 1600 rpm's for 1 hour 15 mins, that will = app one hour on the meter. So as long as it takes app the same time to do the job, I would have 20%-25% less wear on the engine. I can see using this about 1/4 the time I use the pto, but over the life of the tractor, that will added up to a few $1000.

 

[Texasmark]

First, I know if I do it wrong, I will destroy something. I do that all the time anyway, so no big deal. That is the reason I own a metal fabrication shop.
Have plenty of HP, so torque is no problem. 30-45 hp required equipment, 70+ hp tractor.
2100 rpm's = 540 pto
I should be able to put the pto in 750 and then run the tractor at 1500-1600 rpm's and have 540 pto output.
This will be for working in hay. I have 12 gears to play with, to get the right mph needed.
I have run the numbers 10 ways and they all = the 1500-1600 rpm range.
Less work for the engine, less fuel.
Is anyone doing this?

HP = (torque x rpm)/5252. Gear ratios change torque to rpm and rpm to torque. Matters not just divide the ratios and if going down on rpm you will be going up in torque by the same ratio minus the losses in the gear train of the gearbox.

To know what rpm is the most efficient one would have to consult the engine torque/rpm/hp graph. My experience is that the sweet spot is a few hundred rpm above the torque peak. On my MF 35, with the 3 cyl Perkins diesel, torque peak was 1000 rpm with a PTO rating of 1800. On my 6530 the torque peak is 1600 and the PTO is 2600 rated. I have a selector switch whereby I can go 540, 1000, or half way between. When mowing with my 6' shredder, on reasonable height/density foilage, I run the mid PTO selection and set the rpms at 1800. That gives me a torque increase when any load increases and reduces the rpm drop and resultant load on the engine.

That's my opinion.