Farmall-A Fan Assembly - 1 vs 2?

My '40A has a shot fan assembly bearing, that will soon be replaced (teardown this weekend).

On the shelf are two perfectly good assemblies off early A's, except they both have a double pulley. The current one has a single pulley.

I assume the doubles are actually for Super-A's with hyd's??

Will a double pulley assembly fit in there anyway or will it measure too long and hit the radiator?
Thank you, Ken

I think Measure is the operative word.
If it had two, it might be nice to have as a live power source (hydraulic pump?!) Jim

The difference between 1 pulley and two is because the early A"s ("39 & "40) had no electrical systems, therefore no need for a generator, and thus, one pulley (for fan). The later A"s, B"s, & SA"s all had electrical systems, and the second pulley/belt drove the generator.
A 2-pulley fan assembly will work on an A without an electrical system, but a 1-pulley fan will not work on an A with a generator.

That's interesting and I'm glad for the education.

However all three of my A's; 39, 40, & 40 all have single pulley fans with 6V genny's, & stock genny brackets, and all run a single 3-pt belt.

Previous owners must have made adjusted things along the way???

My 40 A has a generator, lights and electrical system and it is all original.

Stuart - how many pulleys/belts are on your fan?

What Davset said is exactly right. The early tractors came with a single flange fan hub. To install a generator for lights and/or a starter required replacing the single flange hub with a double. At serial 54387 (mid-'41) they started setting then up at the factory to ease field installation of electrical equipment. This included the double flange pulley and the starter hole in the bell housing. The ring gear was added to all flywheels at serial 80148, which was late in '41. Lights could have been installed in the factory or in the field.

Any A or B with an IH designed electrical system used a separate generator belt driven by the fan hub. If you have a system with the generator and fan both run by a single belt, it is a modification.

There are two sheaves or pulleys on my fan. All Electrical systems on those tractors were an option. But you can get a 39 or 40 A with lights and starter and such. hope this helps

In 1939 you could order an A out of the factory with lights, starter and gen. My grandpa did.

My tractor is stamped J, so that makes it a 40 model. Thing is if you want to change a bare tractor to one with an electrical system, you have to change the center section for a starter hole.

Great information guys, thank you. I hope it fits without issue. Ken

Somebody added the generator later, and used a longer belt rather than replacing the fan pulley.

Two belts were used to get more belt contact area with the pulley for better "traction" and better transfer of power.

Your A came without a generator so the fan assy only had one pulley. You can replace it with one that does have the two pulleys.

Grandpa was wrong

The early Farmall A came without lights or starters. There was NO provision for mounting a starter. If you had the lighting attachment it was the same as the earlier F-12 O-12 etc. series tractors, the fan pulley was replaced with one that had two sheaves, one of which drove a Bosch "no-battery" generator so that you had lights as long as the engine was running. Either late 1939 or in 1940 the full starting lighting attachment became available and at this point they changed the clutch housing casting to facilitate the fitting of a starter motor. The Bosch 'no-battery' lighting attachment was also available for the bigger Farmalls and the 4 and 6 series tractors but was removed from the attachments list about 1949.
The very early Farmall A had a push-down tab on the magneto to short out the magneto. This was later replaced by a Bowden cable operated tab so that it could be shut down without leaving the seat. The very early Farmall A also had the radiator shutter control leaver sticking out of the radiator grill at the bottom left hand (from back of tractor) grill opening. The prototypes also had a two spoke steering wheel and the front wheels were plain dished wheels (no spokes).

Every now and then, it's nice to see an OFFSET thread that garners such interest, and you see replies fire back and forth between combatants --- I mean "experts".

Gene, Janicholson, etc, --You guys PLEASE keep posting as we all learn so much from those of you who were there way back. Through these posts (and with no crashes) you'll live forever.
Couv