Snow replacing sprockets and chain

[Deadman]

Thanks!:thumbsup:

 

[bellygunner]

I'll put some pics up when I head back out to the barn. Have to go get the chain.

 

[turbo36]

My JD 47 inch blower has that exact same WOBBLE. I tried to tighten the chain last night, but as you rotate it, the slack changes. The owners manual says to tighten chain, and then rotate the auger to make sure there are NO TIGHT SPOTS. So, JD must know the auger wobbles! :confused2:

Is this movement normal, or do you guys think I have a problem? My blower maybe has 3-5 hrs on it!
Thanks

I had the same problem with my 47" blower. After trying many times to get the chain "just right" I pulled the sprocket and measured the bore to be oversize! Unfortunately I was 30 days past warranty and Deere wouldn't replace the pulley. I believe that many of the 47" blowers came with pulleys that were oversize and Deere was pulling a "Toyota" by ignoring the problem.

 

[Henri88]

I had the same problem with my 47" blower. After trying many times to get the chain "just right" I pulled the sprocket and measured the bore to be oversize! Unfortunately I was 30 days past warranty and Deere wouldn't replace the pulley. I believe that many of the 47" blowers came with pulleys that were oversize and Deere was pulling a "Toyota" by ignoring the problem.

Could you elaborate a little more on this. Are you talking about the sprocket hole where the shaft slide in. When I took mine off, it seem to be fairly loose on the shaft. Once you tight the 2 set screws I figure that it could very well bind the sprocket.

 

[turbo36]

Could you elaborate a little more on this. Are you talking about the sprocket hole where the shaft slide in. When I took mine off, it seem to be fairly loose on the shaft. Once you tight the 2 set screws I figure that it could very well bind the sprocket.

The bore was larger then it should have been so when the two set screws where tightened the sprocket would run out of round. Since I am an engineer I understand fits and stack-ups, if my opinion perhaps a .001" to .003" (.025mm to .075mm) clearance would be proper but in my case it was more then .020" (.5mm) In my shop we have a term for this "it rattles around like a pea in a bucket".:laughing:

 

[bellygunner]

Got the new chain on. Had to remove the big sprocket and then the small sprocket housing came right out. It all went back together without a hitch. Ran it tonight for about 2 hours and it works fine. Thanks again for all the comments.

 

[Henri88]

Ok, so here is a follow up on the large sprocket I brought to my dealer. Sorry I'm a little late, but you know how it is before Christmas. Just a quick recap, The large 40t sprocket on my 47'' blower was wobbling side to side, possibly cause by a bend in the sprocket and also as mention by Turbo36 the inside bore of the sprocket seem to be a little large for the shaft. All this made it hard to adjust the chain causing it to be very noisy. Took it to my dealer hopefully for a replacement on the warranty even though the warranty is issue. Well apparently the sprocket was not bend enough to justify a replacement and the inside bore of the new sprocket they had was the same as mine. I decided that the sprocket had to be change but JD was asking $126.00:confused2: So I went at a bearing dealer and bought a sprocket for $38.00. This sprocket is machine in one piece instead of the original 2 piece sold by JD. It is nice and strait and further more, the bore is the perfect size for the shaft. There is absolutely no more loose on the shaft.:thumbsup: Made sure that both sprocket were well aligned and tight everything in place. Also took the time to replace the chain. Now it is much easier to adjust the chain. Still have some loose on the chain being cause by the small sprocket shaft that is also a little crooked. (Don't know who makes these parts for JD, but not impress at all.) All in all, I have eliminated 75% of the slack and noise of the chain by doing this fix and would recommend it without any hesitation.:thumbsup: Here's a few picture of the old and new sprocket. The new one is black and you can see there is no welding on it.

 

[Henri88]

My JD 47 inch blower has that exact same WOBBLE. I tried to tighten the chain last night, but as you rotate it, the slack changes. The owners manual says to tighten chain, and then rotate the auger to make sure there are NO TIGHT SPOTS. So, JD must know the auger wobbles! :confused2:

Is this movement normal, or do you guys think I have a problem? My blower maybe has 3-5 hrs on it!
Thanks

JD recognize the problem and they do consider it normal. They told me that although very noisy, it will not cause premature failing.

 

[Deadman]

In SPRING, my 47 blower is going to my local machine shop, and he can build me a sprocket that is actually straight!

 

[trlong]

beenthere, kennyd...,

Boy does Henri88's picture (12/14/2010) of the drive sprocket shaft look all too familiar! Same blower... the impeller jammed over a month ago (terrible deep slush) and the chain jumped. I'd thought just the shaft housing was bent, bought a new one and put all back together, only to have the chain jump again. Taking all apart, I found the large blower shaft sprocket bent, the small sprocket shaft and sprocket bent, and the back of the forward, inside, pressed flange housing sheared off, along with both eccentric locking collars skewed on the shaft. All damaged parts ordered, delivered, and the dealer was supposed to put it all back together. However, when I got there it was just the parts. Rather than make another trip to the dealer I figured "How hard could it be..." (stupid me!). Fortunately I have a small gear puller that was required to pull the large sprocket, the bearings, and collars off the small shaft. All is "dry fit" back together but I am not sure if the eccentric locking collars should be snug against the front and rear bearings on the small sprocket shaft or...? I have all parts diagrams and list but nothing that says where on the shaft to set the collars to, or spaced from the bearings. Help? Tom

 

[trlong]

Folks,

Never mind. I believe I have found the answer to my own question. The eccentric locking collar on the shaft for the large sprocket is snug against the bearings. Also, searching the web, I found an article on "timken.com" stating "...When assembled on the shaft, this eccentric recess engages, or mates, with an eccentric cam end of a bearing's inner ring. The collar is engaged on the inner cam of the bearing. This assembly grips the shaft tightly with a positive binding action that increases with use...". Hopefully, if anyone else with as little mechanic's experience as I have attempts this repair, this note may help.

 

[caseyvand]

Hey trlong.....does that Timken article say anything about which way to turn the collar? I would guess that the collar would tighten with use if the collar was tighted in the correct direction....it would depend on which direction the shaft turns.
Casey

 

[trlong]

casyvand,

If you search the web for "eccentric locking collar" you should get a hit on Timken and that article. If you look (physically) at the flange on the bearings and the inside of the eccentric locking collar you will see that each is thicker to thinner around the inner circumference. By Timken's description, I "assume" you face the hollow side of the locking collar to the bearing flange with the thickest section of the collar to the thinnest section of the flange and then "set" the collar with the "allen" set screw. As the shaft rotates (makes no difference in shaft rotation direction) the two parts are supposed to tighten against each other. Pretty slick and simple system, per Timken's 1923 patent. The set screw is simply to keep the collar lined up until the motion locks the two together. At least that's what I could glean from the description and diagrams. All is still to be proven when I get the assembly back on the blower, adjust the chain tension (still not sure about how tight) and then test it out. Hope this helps.

 

[caseyvand]

trlong....I read the Timken explanation but they do not make it very clear that you need to turn the collar tight on the inner eccentric bearing race in the same direction as the shaft turns and then tighten the set screw.
Casey