Super A PTO adapter

The neighbor's Super A is waiting for the carb kit and ignition parts to arrive, so when I get back home off of the road, it should be running.

It has a 4' or 5' mounted rotary mower on the back, and he has never tried it. Bought it that way mounted. The pto shaft was stuck and would not slide, got that freed up and all is well. However, tractor shaft is 1 1/8" and the mower yoke is 1 3/8". They have the sleeve adapter in place to joint them, but, give that the S/A has no through hole in the pto shaft to receive any sort of retaining pin, I see no way that the yoke can be trusted to stay put. My suggestion to him is to buy a 1 1/8" to 1 3/8" over running clutch so that the clutch is fastened to the tractor pto, the mower yoke can slide onto the O/R stub, and retain in the groove with the spring loaded locking pin. Since there is not through hole on the tractor shaft, I would think I would need an O/R unit that has its own spring loaded pin. Is that way you guys solve this problem? I use one of that design on my VAC Case and it is nice and easy to remove and swap between tractors, and it really saves on pto brake pads on my live pto tractors. Just looking for a recommendation, and where can I find a 1 1/8"x 1 3/8" o/r clutch that does use a roll pin through the shaft but rather a spring loaded safety pin? It looks like SSB has one but I'd need to see a photo of it to be sure.

Thanks as always.

An OR clutch is very importantAs a child, I learned the necessary tricks to avoid issues, but it is so unnecessary to learn tricks when the clutch is the solution. A machine shop could mill the diagonal hole needed for a bolt to be used for retaining, if none can be found with the spring loaded pin. JimN

F-I-T: Super A have the standard 1-3/8 PTO shaft. Only A from 39-40 had the small shaft.

Good Evenin Hugh,
I have the small shaft on my 42 A. Just as a point of interest !

BTW hello !

scotty

scotty: I wouldn't argue that, I knew it was eraly A. I'm certain they were all gone by Super A days.

Very possible that this "A" just has Super "A" decals, as this is what is on the hood (understnad I'm an IHC Mrookie),but FWIW, this "A", whatever limited super powers it might have, has a 1 1/8" pto shaft.

So, still looking for ways that you folks tackle this problem. No hole to pin through, need an o/r 1 1/8" with speed pin, OR, install a newer pto shaft with 1 3/8" stock....is that a possibility?

I thought even the smaller shaft had a through hole. Any case, the larger shaft from an A, Super A etc. will go right in.

The SA did not have the small pto shaft so just what do you have??

Jim, I think you are correct. I have a 1940 H with the small pto shaft, and it does have the hole in it.

Jim, I think you are correct. I have a 1940 H with the small pto shaft, and it does have the hole in it.

Either: This is a Super A with an early A PTO unit in it.
Or: This is an early A with Super A decals.

Does it still have the serial tag on the left seat support? The number on that tag will tell. If it's less than 250,000 the tractor is an A.

If the tractor doesn't have a hydraulic unit under the gas tank, it is an A.

The PTO unit can be swapped out for one with the modern shaft.

One possible issue with adding the overrunning clutch is if the mower is mounted centered behind the tractor. The PTO shaft is at a pretty good angle already due to the offset PTO on the tractor. Adding the OR clutch to the mix will increase the angle a bit, possibly pushing it into the realm of chattering. If it chatters, it won't last long. Mounting the mower offset to the left so the PTO shaft is straight, it won't be a problem.

It has the hydraulic unit under the tank. I am on the road this week and the tractor is in Florida at my house I can't confirm the S/N until then.

I agree on the O/R clutch unit adding length that would create a more acute angle for the pto, but this mower actually has the gear box canted to point to about 10 o'clock, so they gained quite a bit of that back. Not sure if it was facotry or a farmer mod, but it got back about 60* angle of problem.

If the unit pto is canted as you indicate, it will chatter. The shafts must be pointed in exactly the same direction even if offset to prevent chatter.

After 50/60 years there is no way to predict what may be in tractor, as you say. I have a 1940 M with the 39/40 slot or dog drive PTO so it is 1 1/8 inch, right? No it has 1 3/8 inch PTO.

I thought all M PTOs were 1 3/8, even early ones.

If you say so I believe you, but have always heard early Ms were 1 1/8 inch, have never actually seen one though.

Jim: Not disputing you at all but my Farmall Letter Series Tractors book IMPLIES that early tractors were 1 1/8 inch. "IH adapted the new Farm Equipment Institute PTO standard for the M series on tractor FBK 59987. The new standard involved a 1 3/8 inch splined shaft and a drawbar extension plate. Various field change packages were available to convert older tractors to the new standar."

OK, you make me crack a book open. I believe the older PTO spec was 1 1/8 for tractors under something like 25 hp, 1 3/8 for tractors over. Thus the M would have been 1 3/8.

According to the 1945 Field Tractor Book, the PTO specs by model lists A,B and H as changing both diameter and distance ahead of drawbar, with the change at a given serial number. For the M, they only show a change of distance. They list the M change at 59957. Clearly one or the other has a typo in the serial number.

The conversion package for the A was made up of a new shaft and a hitch plate. For the M it was probably just a hitch plate. An old enough Parts Catalog would probably confirm it.