PTO / GROUND SPEED??

Tod Michigan · Sep 25, 2011

I have a 460 Diesel with no TA. This is probably a basic question for some of you guys but I would appreciate any help.
My tachometer/speed-o gage shows the 540 PTO speed maxed out at about 1750rpm on the thack. In any given gear, if I go above the 1750 RPM's, am I correct to say that the pto "speed" is maxed out and any increase in rpm's would only increase my ground speed? Or does the pto speed continue increasing the entire rpm span?
Thanks,
Tod Michigan

Bob · Sep 25, 2011

"does the pto speed continue increasing the entire rpm span?"

Yes.

Brendon-KS · Sep 25, 2011

Another way to describe it is that the PTO speed and engine speed are directly proportional to each other at all times. For example, if you increase engine speed by 10% the PTO speed will also increase by 10% regardless of what RPM you were at when you started.

JRSutton · Sep 25, 2011

Yes, one way to think about it is that the pto is like an extra wheel with it's own one speed transimission.

It's either in gear (on) or in neutral (off).

The pto's speed is directly related to your egnine rpms. (not sure exactly what the gear ratio is... but say for kicks it's 3:1 - every 3 engine revolutions = 1 pto revolution)

It doesn't matter at all what gear your wheels are in. that's a separate system

There's nothing that starts slipping or limiting the pto once it gets to it's proper speed.

It's exactly like your wheels, it's a very simple direct connect to the engine.

The faster the engine turns, the faster the pto turns.

Tod Michigan · Sep 25, 2011

That's what I thought. I couldn't understand how it could be affected by the idle at low rpm's and not at high rpm's.
So, most pto driven equipment calls for a 540rpm pto. They must know that we're gonna go beyond the 1750 rpm's and therefore also beyond the 540rpm, while we work up many acres. So what's with the 540 pto?
I'm guessing that the mark at 1750rpms, which marks 540 pto rpm's is there as a reference. So we do know where that spot is. I guess 540 is as good a number as any!
One last thought. Maybe I've made one too many trips around the field this year. I bet everyone has thoughts and questions that probably seem totally legit while your on that tractor and then later after you've already asked the question or made the comment the whole thing might strike you as a little strange. Maybe. Ha, I hope so. Lol.
Thanks for any help,
Tod, Michigan.

Anonymous-0 · Sep 25, 2011

It's a reference. Some pro driven equipment in the 60s and 70s required 540 rpm for proper performance namely hay Balers and feed grinders.

Sam#3 · Sep 25, 2011

What everyone said plus the 1750 rpm is probably the published nominal speed for the engine. Those old long stroke engines weren't meant to rap-up like a modern short stroke auto engine.
You adjusted ground speed by gearing up/down.

Janicholson · Sep 25, 2011

One more comment to that below.
The rated PTO speed is the rated engine speed when the rated Horse power is developed. The PTO will go beyond the 540 (or 1000 on higher HP tractors) at wide open unloaded operation(High Idle). All of the 540 designed equipment is designed with this factor in mind, and is not destroyed or harmed in any way with the tractor wide open. The only bad thing is to run newer 1000 rpm equipment at 540, or 540 equipment explosively at 1000. THey use different splines to make it difficult, but there is always a way to be wrong. Jim

JRSutton · Sep 25, 2011

"I bet everyone has thoughts and questions that probably seem totally legit while your on that tractor and then later..."

Absolutely!

Tod Michigan · Sep 25, 2011

Thanks to everyone for all your input. This forum is very helpful and the people in it are very knowledgeable. The best part is that you are all willing to share your knowledge with us who need it. I Hope I can help someone equally someday.
Tod, Michigan.

mkirsch · Sep 26, 2011

I haven't seen it mentioned, but 540 RPM is the industry standard for low-HP agricultural PTO systems.

Every tractor manufacturer designs their PTO to turn the same speed, so every manufacturer's implements will be compatible with every tractor. It's been this way since the 1930's at least, maybe longer.

F-series Farmalls have a PTO that runs at 535 RPM.

There is probably an interesting story around how the industry came up with 540 RPM, and not an even number like 500 or 600.

JRSutton · Sep 26, 2011

"but there is always a way to be wrong"

I like that line.

PTO / GROUND SPEED??

Tod Michigan

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Bob

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Brendon-KS

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JRSutton

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Tod Michigan

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Anonymous-0

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Sam#3

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Janicholson

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JRSutton

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Tod Michigan

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