Hydraulic Pump Gear and Key Fitment Question

[AL Farmall Boy]

Does anyone know if any Cub hydraulic pumps used a different size woodruff key on the pump shaft? This would in turn change the size/fitment of the gear also. I have a pump that was missing those 2 parts and I tried a key and gear from another Cub pump and can not for anything get the gear to fit. The key was pretty hard to fit too. If it helps, my pump is a lip seal type and the gear and woodruff key are from a pump with the shaft o-ring.

[Barnyard]

Should all be the same.

[Crimson Tim]

If you found a lip seal in there, then someone has already altered at least that much. The pumps used o-rings from the factory throughout production.

So the key and the gear were matched together from a different Cub? Things should be a very precise fit. What prevents the gear from going on? The key or the shaft? The key can be a slippery bugger and shift around on you while you’re trying to slip the gear on. If it’s not lined up just right, it won’t go.
Also, if the keyway got messed up, someone could have welded it up and remachined the groove, so maybe the machining tolerances worked for the original gear, but not for your substitution.

Also also, did you fish around in the bottom of the engine for the missing gear? If the tabbed washer is omitted or fails, the pump nut and gear will come off into the bottom of the engine.

[AL Farmall Boy]

I thought they all were the same. It might work better if I replace the old key with a new one. Some of the older pumps did have a regular type oil seal in them. Thanks guys.

[Crimson Tim]

I thought they all were the same. It might work better if I replace the old key with a new one. Some of the older pumps did have a regular type oil seal in them. Thanks guys.

That’s right. The original pumps had thick a leather seal, if I recall. Not sure when they changed to the o-ring. But a lip seal is decidedly modern.

[AL Farmall Boy]

* NEWS FLASH *

I got it installed without any fuss. I replaced the Key with the correctly sized #3 that I found in my hardware drawer and that was the problem. Any kind of little burr will keep thinks frol working correctly. Can’t wait to get this on my Cubbwnd see how the rebuild went with the lip seal. Thanks for clarifying that the parts are the same, and giving me the little confidence to keep trying and not calling it a night!

[John *.?-!.* cub owner]

I thought they all were the same. It might work better if I replace the old key with a new one. Some of the older pumps did have a regular type oil seal in them. Thanks guys.

That’s right. The original pumps had thick a leather seal, if I recall. Not sure when they changed to the o-ring. But a lip seal is decidedly modern.

I have one of the old pumps that came with a leather seal. Unfortunately it had worn a pretty bad groove on the shaft, but the new replacement seals are much thinner, so it was easy to seat the new seal in a different place to avoid the groove.