Why 540?

[mcfarmall]

Why not 500 or 632 or whatever?

There must be some mechanical basis for standardizing on 540 rpm for PTO speed.

Let's light it up, tractor gurus!

 

[Norm W]

Many of the old engines (open fly wheel) ran at 550 no load, 540 under load. I think it is just a carry over from the flat belt days.

 

[CalG]

A close enough factor of electric motor rpm based on 60 cycle electrical systems.

 

[joeu235]

Tractors were designed by folks who had a Base 9 number system.

 

[mcfarmall]

Many of the old engines (open fly wheel) ran at 550 no load, 540 under load. I think it is just a carry over from the flat belt days.

You mean like the hit and miss types, oilfield engines, etc.?

 

[kthompson]

Just wondering, in today's world some very good rpm meters but how did they know it was 540 that many years ago?

 

[Motorboatin]

From Wiki.......“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.”

Power take-off - Wikipedia

 

[RickB]

A close enough factor of electric motor rpm based on 60 cycle electrical systems.

I can’t recall any electric motors running at 540 rpm.

 

[Wagtail]

From Wiki.......“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.”

Power take-off - Wikipedia

Well, there ya go. Learnt something today.

= no matter what, the day wasn't wasted.

 

[mcfarmall]

From Wiki.......“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.”

Power take-off - Wikipedia

So the question still stands...Why 540? Why did the ASAE in April of 1927 decide that the PTO rotational speed was to be 536 +/- 10 rpm?

I don't understand the 60 cycle electric motor explanation...the common speeds for AC motors are 1725 and 3450 rpm.

I believe the early engine speed comment has merit and could be a good starting point for the ASAE logic.