PTO size

Jay Liedman · Dec 26, 2020

Just curious as to if anyone knows what the reasoning for the change from the smaller to the larger diameter PTO? I assume the change was in the late 30s or early 40s.

SVcummins · Dec 26, 2020

Transfer more horsepower . There is also small 1000 and a big 1000 for the big tractors

rustred · Dec 26, 2020

More h p needs stronger pto.

David G · Dec 26, 2020

Do tell more.

Dieseltech · Dec 26, 2020

Early tractors had 1 1/8 inch 6 spline 540 shafts. Later was increased to 1 3/8 inch to handle the torque better. Then as power increased the 21 spline 1 3/8 1000 RPM shaft came available. For even larger tractors a 1 3/4 inch 20 spline is used.

SVcummins · Dec 26, 2020

3020 and 4020 have 1 1/8 540 and 1000 shafts I can’t remember the other sizes without digging through my books

Charlie M · Dec 26, 2020

I know the Farmall line was changed from the smaller size to the bigger size around end of 1942 or early 1943. I think one of the things that move did was to standardize the size for everyone. Probably someone knows the date the change officially occurred.

Dieseltech · Dec 26, 2020

Both are 1 3/8 inch, not 1 1/8..

David G · Dec 26, 2020

Thanks

SVcummins · Dec 26, 2020

Ted in NE-OH · Dec 26, 2020

I have seen 1-1/8 pto's twisted off.

fixerupper · Dec 27, 2020

The small PTO on my 35 A Deere is twisted. Been twisted for as long as I can remember.

tim s · Dec 27, 2020

more horse power is the reason,,,and the 1,000 RPM shaft deals with the higher HP better,,and then the even larger shaft is not big enough at times,, my Nephew twisted off the shaft in a 4960 last week running a 20 ft mower.

Pappy · Dec 27, 2020

I think my "G" has a bigger PTO shaft. Probably a 1 5/8". Not close by to measure.

Brendon-KS · Dec 27, 2020

The Deere "G" was one of just a few tractors that used a 1-3/4", 6-spline, 540 rpm shaft. My Unimog 406 also uses this size of PTO shaft but fortunately adapters are available to get it down to the usual 1-3/8" size.

PTO size

Jay Liedman

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SVcummins

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rustred

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David G

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Dieseltech

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SVcummins

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Charlie M

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Dieseltech

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David G

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SVcummins

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Ted in NE-OH

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fixerupper

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tim s

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Pappy

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Brendon-KS

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