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back before tachs how was pto speed determined ?,was all the different manufacters use the 540 standard speed ?,how come they went to 1000 rpm ?,say on a 1000 rpm bushhog does the blades spin twice as fast as a 540 bushhog ?
 
"The first industry standard for PTO design was adopted by ASAE (the American Society of Agricultural Engineers) in April 1927. The PTO rotational speed was specified as 536 ? 10 rpm; the direction was clockwise. The speed was later changed to 540 rpm."

Going to the higher PTO speed allows more horsepower to be carried by the same size driveline, NOT sure why they settled on 1000, though.

Typically, when a PTO-driven machine is available in a choice of 540 or 1000 RPM PTO there's a change in gearing, sprockets, or belt sheaves to keep the machine running at close to the same speed with either option.
Source
 
Bob has it very good.

To add a bit, it is difficult to transfer over 75-100hp through a typical 540 pto shaft. Unless you get creative and expensive, the metal wants to shear off.....

Those giant grain augers you see to make piles of corn outdoors, they might take 125 hp and they run on 540rpm so they don't need a gearcase..... it's real common to break something, the stub coming out of the tractor, or a gear inside the tractor, with those, it is the limit of what that size and speed of shaft can handle, even with the exotic metals some companies like ihc used to make the parts.

so they went to 1000 rpm so twice as much hp can be transferred. As well 1000 pto seems to have 2 standard size spline patterns....

Actually the first tractors has a small size 540 pto shaft - Ford 9N, Farmall H, etc. they had so little hp the smaller shaft was fine.

A bush hog has a 'best' rotating speed, and it will be geared to that speed. 1000rpm machines do -not- run twice as fast as 540 machines.

Paul
 
Implements (threshers/combines/balers/etc) which had their own engine would be run at a factory pre set governed speed.

My father had a hand held tach for checking shaft speeds on PTO powered pull type equipment. This was very crude as the speed was always checked in a no load condition. This tach was also used on the early combines which had their own engines, to check cylinder speed changes.
 
As the others have indicated the implement is designed to run at the same speed regardless of what speed of PTO shaft is driving it. It is common for implements that need a gearbox in the driveline anyway to use one with a 1.35:1 ratio. This provides the same output speed (730-740 rpm) from either 540 or 1000 rpm input speed depending on which direction it is assembled. This minimizes the number of unique parts betweem the two versions and makes for simple field conversion.

You can think of mechanical power, speed, and torque the same as you do electrical power, amps, and voltage. Higher rotational speeds will deliver more power with the same amount of torque just like higher voltage will deliver more electrical power with the same amperage. A 1000 rpm driveline can deliver double (well, almost) the power as the same strength of driveline could at 540 rpm. Somewhere around 80 hp is where it becomes physically impractical to have a driveline heavy enough to withstand the torque of a 540 rpm drive.
 
All the older tractors I have been around are simple to find PTO speed. Wide open throttle under load was generally the engine speed needed for 540 on the PTO.
AaronSEIA
 
(quoted from post at 01:38:07 12/16/17) back before tachs how was pto speed determined ?,was all the different manufacters use the 540 standard speed ?,how come they went to 1000 rpm ?,say on a 1000 rpm bushhog does the blades spin twice as fast as a 540 bushhog ?
n the early days, a hand held Veeded-Root counter with a rubber tip was held against end of pro shaft to count revolutions and you measured time interval of one minute with you watch. Such counter is just like the odometer part of old car speedometers Several wheels where the next is incremented by one digit each time the lesser wheel nMakes one revolution..a simple device.
 
I think it's somewhat idiot proof because the shafts are different, unless some idiot buys some adapters and does something he shouldn't. Like Brendon said, you can transmit more horsepower through a given shaft if you rotate it faster. When I was young none of our tractors had tachs and we never thought about it, we just run them close to WOT. The only time I could see it being an issue is running a pto combine, where rpm is more critical.
 
I think most governors would run wide open around the 540 RPM.

The 1000 RPM PTO was developed to reduce the torque on the splines given same HP.
 
Not on some foreign built tractors most Yanmars have 540 and 1000 on the same stick even had a 1300D that had 540,750 and 1000 on the same stick.Handy when running
a tiller.
 
Bit of history here as it was explained to me in college.

The main reason we had 540 for so many years is that is the optimum speed that a cutterbar works at. IE 1080 strokes per minute. Any faster and you are just wasting fuel etc as it won't cut anymore grass or grain. Of course binders and sickle mowers were the first implements to use PTO commonly. Much later in the picture came the grain auger but the exact same principle applies here. All you do when cranking up the speed on your auger is tear up equipment, beat up the grain, you won't auger anymore than at 540 or actually 600 comes to mind as the ideal speed but it is in that range.

Putting your M&W nine speed in high won't gain you anything when on the auger.

1000 as others have explained was to allow more power to be transmitted through a 1 3/8 shaft.

jt
 
You can check them with one of these.
a250510.jpg
 
(quoted from post at 09:24:46 12/16/17) I think most governors would run wide open around the 540 RPM./quote]

What one would THINK doesn't always hold true. High idle on many tractors was quite a bit above rated PTO speed.

Using a simple Ford 8N as an example, 1500 engine RPM's gave approximately 545 RPM's at the PTO, rated engine speed was 2000 RPM's, giving a PTO speed of 727 RPM's at full throttle, and there many other tractors set up in a similar fashion.

Looks like 1500 RPM's was the maximum torque speed of the little 8N's.
 

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