Why 540?

[Langanobob]

Here is the link where I found the info. Of course it’s just more internet info but it seems to make sense.

54 RPM PTO Why - General IH - Red Power Magazine Community

 

[mcfarmall]

Thanks for the link, Lang! My thirst for knowledge has been satisfied!

 

[MHarryE]

Picking a McCormick sickle speed seems odd. Sickle mower patents go back to the early 1800s. In the 1970s we worked on a design with springs at the ends. Stopping the sickle stored energy in the spring that was released to send it back where the other spring stored energy on that end. When our patent attorney looked into patenting this brilliant idea he found it had been patented before the civil war. The need for speed is that the sickle mower is a very poor cutting mechanism yet the vibration helps clean the mower or most common now combine cutterbar. The tale does make sense because you need to start somewhere. At one time I had a collection of dozens of sickle bar patents it would be interesting to review now but I trashed them when I retired.

 

[Atchuuu]

This is probably accurate since I seem to recall the first Tractor with a PTO shaft was an IHC product.
No, I don稚 have a source or link to that dim memory nugget.

The most efficient and economical method of transmitting power from an agricultural tractor to an agricultural implement is through a power take-off (pto) driveline. The agricultural tractor to implement driveline presents a challenge to the engineer because the universal joint angles vary continuously in three planes and telescope continuously in length, which requires a knowledgeable selection of components to attain a reasonable uniform transfer of motion. Most agricultural drivelines are designed for standard tractor pto shaft sizes and speeds. Other drivelines are used internally in the agricultural implements. International Harvester introduced the first practical pto on a farm tractor in 1918. The 540 rpm pto shaft, master shield, and drawbar relationship standard was developed by Equipment Manufacturers Institute (EMI) and American Society of Agricultural Engineers (ASAE) in 1926. In 1958 a standard for a 1000 rpm tractor pto shaft was published. In 1966 a pto shaft standard was published for higher horsepower tractors. The ASAE S203 (1994) or SAE J1170 (1993) standards give the details of the tractor pto shaft dimensions which have the following basic data:

ASABE Technical Library :: Abstract

 

[npalen]

The sickle speed reason sounds a bit erroneous as there is usually some gearing between the PTO and the sickle. The crank throw distance on the sickle drive would also control the surface speed of the sickle.

Edit: Horse drawn sickle mowers would have even more speed variation as the horses didn't have PTO.

 

[Atchuuu]

I couldn't find any real "proof" that the PTO speed was chosen to match the McCormick sickle. The only source I see is a forum where it is mentioned briefly.

I did find this book on the creation of International Harvester Company and the products they were working on. This includes the PTO that was developed by Edward Johnston. This thread grabbed my attention but not enough to buy the entire book. You can preview the book up to page 27 for free -

International Harvester Tractors - Randy Leffingwell - Google Books

 

[buickanddeere]

I can稚 recall any electric motors running at 540 rpm.

I was thinking that as well.

60Hz would be 3600,1800,1200,900,720,600,514 and etc.
25Hz which was Ontario, NY and area would have been 1500,750,500, 375 and etc.

 

[buickanddeere]

In hind sight the 1000rpm pto should have been an 1800rpm pto instead.

 

[cdaigle430]

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!

Why do hot dogs come in packages of 10 when hot dog buns come in packages of 8?

 

[k0ua]

Why do hot dogs come in packages of 10 when hot dog buns come in packages of 8?

Actually many now are coming in packages of 8. At least the last ones we bought were.