An Idea Whose Time Has Come

[OkieDave]

Fixed-speed PTO.

Think about it--a PTO that always turns 540 RPM, regardless of throttle setting. Could be a hydrostatic drive, could be CVT, could be lots of things, but it always gives you the proper speed, regardless of how much power you're actually delivering.

The multi-speed PTO guys know what I'm talking about: with a 540/1000 RPM PTO, you can select 1000 RPM and run a half-throttle to get the same 540-ish, but burn half the fuel on jobs that don't need the extra power. JD is even advertising this feature under the name "Economy PTO." We all know what it really is--a two-speed PTO, with a second marking on the tach to tell you where to get 540 RPM when set to high-speed.

So why not? Why not a system that will maintain 540 regardless of input power? I mow my lawn with a brush hog; the hog will happily cut 3" saplings, but I do that once, maybe twice a year--most of the time, it's 3" tall grass. I don't need the full 25 HP my PTO delivers at 540; frankly, I suspect 5 HP would be enough as long as it was delivered at appropriate speed. Give me that, and I'll be at the Diesel pump twice a year instead of once a month.

What do y'all think? Am I just crazy, or am I on to something?

 

[oldnslo]

I can think of one application where this technology is being used today and that is truck mounted cement mixers. As they drive down the road and the engine RPM varies the drum turns at the same speed. These are Hydrostatic drive systems.

I suspect the cost of this feature would probably make it prohibitive on small tractors.

Roy

 

[blueriver]

I quess I just don't understand PTO's ... take for example all my equipment is 540 rated .. so what your saying is when I hook up for example my disc mower and go to cutting hay I can set the PTO lever to 1000 and run my tractor at half rpm's? At half throttle would I not be lugging the diesel engine?

I was under the imression that some of the equipment you buy may be 1000 rated not 540 and that would be the only time I'd use the 1000 but I would still run the tractor at the PTO rpm's.

 

[leonz]

I quess I just don't understand PTO's ... take for example all my equipment is 540 rated .. so what your saying is when I hook up for example my disc mower and go to cutting hay I can set the PTO lever to 1000 and run my tractor at half rpm's? At half throttle would I not be lugging the diesel engine?

I was under the imression that some of the equipment you buy may be 1000 rated not 540 and that would be the only time I'd use the 1000 but I would still run the tractor at the PTO rpm's.

No, you need to buy the 1000 to 540 adapter
stub to install over your 1000 R.P.M., shaft stub assuming it is the
20 plus spline stub intended for 1,000 R.P.M., implement use.

 

[Duffster]

I suspect the cost of this feature would probably make it prohibitive on small tractors.

Bingo.

I can't think of to many things I do were I would want to run the tractor at less RPM any way.

Also when concrete mixers want max barrel rpm they have to have max engine rpm as well.

 

[blueriver]

No, you need to buy the 1000 to 540 adapter
stub to install over your 1000 R.P.M., shaft stub assuming it is the
20 plus spline stub intended for 1,000 R.P.M., implement use.

My tractor has the standard 6 spline 540 PTO ... I do have a lever in the cab to change to 1000 ... so as I asked when I hook up the disc mower to the pto 540 shaft and then shift the lever to 1000 I would run at 1/2 throttle?

 

[wny770]

What about a post hole digger?

 

[OkieDave]

My tractor has the standard 6 spline 540 PTO ... I do have a lever in the cab to change to 1000 ... so as I asked when I hook up the disc mower to the pto 540 shaft and then shift the lever to 1000 I would run at 1/2 throttle?

Yes. It's just like the gears in a manual transmission: if you shift from 1st to 2nd, your engine RPM goes down, but the tires turn at the same speed. The downside is that, even though you're going just as fast, you're delivering less power to the wheels, which you notice when you step on the gas and the car grumbles at you instead of leaping to action. If you need the power, you stay in low gear; if you're cruising on the highway, you go to high gear and trade the responsiveness for lower fuel consumption.

Now, if you're doing something that requires the full power output of your tractor, and you try to run it at half-power, it's going to bog down. If you're doing light work, though--such as mowing short grass with a brush hog capable of cutting small trees--you're nowhere near needing that full power.

 

[Hooked_on_HP]

I can think of one application where this technology is being used today and that is truck mounted cement mixers. As they drive down the road and the engine RPM varies the drum turns at the same speed. These are Hydrostatic drive systems.

I suspect the cost of this feature would probably make it prohibitive on small tractors.

Roy

On mixers drum speed does change with engine RPM's. You control drum speed with the amount of hydraulic pressure coming out of the variable displacement hydrostatic pump. This is manually controlled by the driver.
Bill

 

[leonz]

My tractor has the standard 6 spline 540 PTO ... I do have a lever in the cab to change to 1000 ... so as I asked when I hook up the disc mower to the pto 540 shaft and then shift the lever to 1000 I would run at 1/2 throttle?

If that is the case with your mule you should have a set engine speed marker on the dash boards tachometer that gives you the proper engine speed setting for the conversion speed for the towed implement