JD 4420 Fan Variable Sheave

Looking for some insights, if any one has done this before. I need to get the upper variable speed sheave for the cleaning fan off the shaft to replace the bearing. This is the sheave with the crank adjustment on it. I've got the outside half off but can't get the back side half to budge yet. Got it soaking with PB Blaster for now. Set screws are out with PB down the holes. The parts breakdown shows a second snap ring, looks to me like it is behind this half of sheave in parts drawing but I can't see it - they are very small. Question I have for anyone who has been in there is; where is this snap ring? Could it be hiding under the chamfer on the outside of this half (between the two halves of sheave)? I have tried bumping it back with a deadblow hammer but got no movement. Thanks, Paul

I'll try to load some pictures.



Number 14 in the schematic is the snap ring I was asking about. Tried heat today after soaking with pb blaster since Saturday afternoon and still can't get it too move. Any ideas? Thanks Paul

I believe that #14 snap ring only holds the sprocket (#15) in place.

I found some info in the technical manual. Step #15 in the manual says to drive the rectangular key out and then pull the sheave half off.

I have not had that apart on our 4420 though.

I hope this helps!

Lon


<img src=https://www.yesterdaystractors.com/cvphotos/cvphoto106639.jpg

Thank you very much LonM. I had been toying with the idea of driving the key out to see if that would loosen things up, maybe even try to turn the sheave half on the shaft once key was removed. Guess I was on the right track! Only problem I see is that my brother boogered up the keyway a bit behind the sheave when he tried wedging it off with a couple of chisels.Now I know to get the key out for sure! Thank you, Paul

After reading further, it looks like when reassembling, the sheave needs to be seated on the shaft in a certain place. I'm glad you found the info useful, and I hope things come apart and go back together easy for you.

Take care,
Lon

LonM, wanted to give you a bit of an update on my progress. The snap ring I had questions about is one of those plain ring things, not a typical snap ring with ears on it, and it was under the back side of the stationary half of the variable speed sheave so no way to see it with the sheave half in place. Wednesday morning was pretty cool, about 20 degrees F, thought what the heck and put the puller on it again and it came off as nice as you please. Don't know if it was the soak from Saturday finally loosening it up or the cold temperature shrinking things at different rates, but it came off. The snap ring was stubborn but came free after half hour or so. The drive gear was a difficult thing, mainly because it is so far back on the shaft a regular puller won't work. It was free enough to slide by hand about a half inch then would get tight. I'll try to put a picture up of what I used to get it off at some point. Also forgot to mention the snap ring under the sheave blocked the key from sliding out so had to pull that all together, no driving the key out like your book said. After getting this far we decided to replace a few more parts that are getting worn so I'm back to waiting on parts to come in. Going to try pulling the whole shaft out the right side like your book says, to change the bearing on that side instead of fighting to get the 4 sheaves off that side. I'm hoping there will be enough room to the fuel tank to do that. Thank you for your information, It helped quite a bit. Paul

I'm glad the sheave half finally came off for you. I have replaced the bearing on the right side of the machine on that shaft. One pulley is really large and it was hard to get my puller attached to it. I took pictures of all three pages from the service manual that pertain to that shaft (the pictures above show part of that section, while these three are the Secondary countershaft section in its entirety.

Take care,
Lon

Photos attached (hopefully)

Thank you for the additional information/pages, I'm sure they will come in handy. I pulled the right side apart today as I was going to replace that bearing as well. I noticed in the previous pages the technical book said you could pull the entire shaft out the right side but it didn't take long to figure out that big sheave was never going to go past the fuel tank. For the big sheave removal I first punch marked it for orientation then unbolted it from the cast hub so I could get down to something more substantial for the gear puller to hook to. I also took pictures of each sheave before I pulled it showing the placement on the shaft for reassembly locations.

The right side is where I think my problems started leading to a complete failure of the left side. The bearing on the right had come loose from the lock collar and wore the shaft down quite a bit. I'm going to buildup the shaft with weld and turn it back to size. It has been a long time since I did that, hopefully I still have those skills, lol. I even came across my 8 gear puller today, I had been looking for it all week and just gave up, thinking I was mistaken that I had one. Thank you again LonM, Paul