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The driveshaft chain failed on my 2008 John Deere 47 inch two-stage snowblower ( OMM145749 K6), and I found scant information online on the chain replacement procedure. The online JD manual for this snowblower lacks any mention. It’s a simple job, once you have a bit of documentation. So here’s my experience, with the prices I paid at a local dealer. Any corrections/additions are most welcome.

The replacement JD roller chain (AM121965, $16) is a continuous chain. Friends advised buying a length of bulk (apparently) ASME 40 roller chain and closing it with a master link or e-clip, but my dealer warned that wouldn’t be as reliable as a new continuous chain.

To install a new continuous chain, you need to temporarily loosen the drive shaft from the flanged bearings within the snow thrower’s chain shield. You can do this without disconnecting your hydraulic hoses.

Disassembly:
Rest your 240 lb. snow blower on a small dolly, lift the blower off the front hitch bracket, disconnect the driveshaft from the front PTO, and rotate the blower away from the tractor, being careful to not stretch the hydraulic hoses.


image: Snowblower on dolly with Upstop (PTO shield) removed.

Remove four M8 bolts and nuts attaching the upstop (AKA the PTO shield), which straddles the top of the snowblower rear. The above picture shows the upstop removed.

Remove the four lock nuts which secure the chain shield. Note that the nuts are placed on the outside of the shield.

The chain shield contains two sets of flanged bearings. The driveshaft extends through one bearing set. The far end of the driveshaft is anchored in another flanged bearing by an Eccentric Locking Collar (ELC) (JD8554, $3; replacements complete with a locking set screw). I opted to replace my loose collar.


Cupped side of Replacement Eccentric Locking Collar (JD8554).

Remove the three bolts attaching the rear flanged bearing to the chain shield.


Rear flanged bearing detached from chain shield.

If the ELC on the snow thrower end of the drive shaft is still attached, your drive shaft is still secured to the front flanged bearing. Loosen the locking set screw on the front ELC. Then use a pin punch (e.g. 5/32”), tapping the ELC in its provided recess to rotate the ELC counter-clockwise when facing the tractor from the rear.

The eccentric locking collar caused me lots of confusion, in part due to conflicting info on the Web. In my case, the ELC was loose on the driveshaft, and the set screw designed to help lock the ELC to the driveshaft was missing. A good discussion of ELCs is available at Sandy Lake Implement.

Once the rear flanged bearing is unbolted and the ELC is detached from the front flanged bearing, you can retract the drive shaft from the front flanged bearing.




Reassembly:
Reposition the front end of the driveshaft assembly as needed to slip the new chain around the drive shaft. Temporarily drape the chain behind the smaller sprocket.

Re-secure the ELC to the front flanged bearing: slip the ELC over the drive shaft with the cupped end towards the front of the tractor. Rotate the ELC clockwise (in the same direction as normal driveshaft/PTO rotation) to lock it to the front flanged bearing. Use a pin punch to rotate the ELC clockwise and securely lock the ELC to the shoulder of the front flanged bearing. Then apply mid- to high-strength thread locker to the ELC set screw and tighten the set screw.


New ELC locking drive shaft to front bearing; chain mounted around drive shaft.

Attach the rear flanged bearing to the chain shield with three bolts. Loop the chain over the large sprocket, verify rotation, and don’t forget to apply some chain lube.

Reattach the four chain shield locknuts, being careful to adjust the chain slack to the specified chain deflection of 3/16 – 3/8 in. (4.7 – 10mm). The chain shield tends to slip when it’s tightened down, so you may need several attempts before the chain deflection is within specification. Verify deflection throughout full rotation of the chain. Any dramatic variance suggests you may have sprocket wear or damage.

Now you can reattach the upstop, remount the snowblower, reattach the PTO, etc.

Good luck!
 

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I did this to mine this past fall. Mine failed for 2 reasons. 1 The roller chain was shot. The rollers were cracked and or missing. 2 the shaft the smaller sprocket is welded to had actually slid into the impeller housing. I found a ELC cracked. I replaced the 2 bearing for that smaller shaft, both ELCs and and bought #40 roller chain from TSC. All is well so far with mine. Toughest part with mine was dealing with all the grease inside the chain housing. The previous owner must have thought the more the merrier.
 

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Nice write up.

Just a note on locking collars: there's no guarantee that they'll be locked in a certain direction from the factory or whoever worked on it before (that goes for everything.. not just blowers). When you're reassembling something, lock the collar in the same direction of primary shaft rotation (as some shafts turn both directions) so you'll know for sure if you ever have to take it apart in the future; clockwise/ccw/etc can be confusing as it's relative to point of view.
 

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I think the main reason there usually is no master link from the manufacturers is cost. A master link adds a few dollars to the cost of a chain and over the course of building many, many machines, it adds up. I have put many, many, many miles on my motorcycles and they have all had chains with a master link. I wouldn't worry a bit about having one on a blower. Not to take away from your post though, very nice write up and good job on the install. The pictures are always worth a thousand words.
 

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I want to thank you. I just lost my chain while snow blowing. I was ready to do a bunch of research to figure out the part, other parts to replace, etc, etc.

Anyway, with this post, and you helpfully posting all the part numbers (THANK YOU!) I wanted to say thanks and that you've provided a great service!

Take Care
 

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Good info, thanks
 

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Thanks for the info .Just completed the same task bought a full roll of sch 40 chain and master links. Always check the sprockets for alignment as a slight misalignment will cause wear or have the chain to come off. I have two 47 inch blowers .
 

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While I appreciate that the 47/54 snowblowers are shaft driven, I wonder why JD has stuck with the chain drive. Seems like a properly-sized multi-rib belt or cogged belt would be a better alternative.
Good question. It seems that almost all snowblowers use a chain drive. 3PH units drive the impeller directly and drive the auger with a chain. While most front units drive the impeller with a chain and then use a front gearbox for the auger. I don't think I've ever seen one using a belt of sorts.
 

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Luckily my chain broke a couple years ago. Took it to the local handyman who cut me a length off his bulk spool, and a connector.
Now I keep extra half links and connectors just in case.
Good write up on remove/replace of parts for those that need more than a chain.
 

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BTW, where is a good place to purchase some good quality chain by the foot (and master link) for use as a replacement?
 

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Ask your local Deere dealer. Mine carries all sizes of bulk roller chain. And I was a parts man there for about a year, so sold quite a bit. We sold it by the link, off a big spool so customers got only what they needed. Deere also has 10' length boxes, but that would make several snow blower drive chains.
Farm supply stores might sell bulk, so ask.
 

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Great thread. I did the same job to mine last fall as well.
 

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I call BS on roller chain with a master link being weak. Most chains are installed with a master link. Think bicycles. You do not have take half the machine apart to change out the chain. Many industrial applications are put together with a master link. Especially if a tension-er is part of the install.
 

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I call BS on roller chain with a master link being weak. Most chains are installed with a master link. Think bicycles. You do not have take half the machine apart to change out the chain. Many industrial applications are put together with a master link. Especially if a tension-er is part of the install.
I tend to agree. Especially a "properly installed" master link. I raced 500cc dirt bikes for many years in the mud and rocks and wore out many chain and sprocket sets but never encountered an issue with a master link. While I currently have a spare OEM chain for my 54" blower I intend to pick up a spare hunk of chain with a master link just in case. That would allow for a quick repair should I break a chain in the middle of a snow-pocalypse. :)
 

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Excellent writeup.

While I appreciate that the 47/54 snowblowers are shaft driven, I wonder why JD has stuck with the chain drive. Seems like a properly-sized multi-rib belt or cogged belt would be a better alternative.



Andreas
A ribbed belt can not be used in a situation where something can get between the belt and the pulley, such as snow. It will cause the belt to come off or break.
 

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Nice write up with OEM part numbers. I suspect the service writer at the dealer is just spewing B.S. to sell new expensive parts.

Have any of you changed either of the sprockets to speed up the blower? I picked up a 47 blower this year and only used it once so far on my 425. I would like to spin it faster to see if I could get some more throw distance. I have a terrible driveway in front of my garage with 6' retaining walls on each side. Blowing out and over them is a challenge. I'm debating keeping the blower or just continuing plowing up the hill, away from the garage.

 

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A ribbed belt can not be used in a situation where something can get between the belt and the pulley, such as snow. It will cause the belt to come off or break.
In case you are not aware, JD recently changed the design on the 47/54-inch snow blowers to replace the open chain and sprockets with an enclosed heavy duty chain that runs in an oil bath inside a heavy cast iron case. The great thing is this "gear box" can be retrofitted to earlier snow blowers AND it costs LESS than the price of a set of replacement sprockets and chain. It greatly simplifies the design and maintenance requirement for the snow blowers.

2446594
 

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I would like to spin it faster to see if I could get some more throw distance. I have a terrible driveway in front of my garage with 6' retaining walls on each side. Blowing out and over them is a challenge. I'm debating keeping the blower or just continuing plowing up the hill, away from the garage.
Just replace the plastic impeller with the steel impeller and your problems will be solved.
 

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In case you are not aware, JD recently changed the design on the 47/54-inch snow blowers to replace the open chain and sprockets with an enclosed heavy duty chain that runs in an oil bath inside a heavy cast iron case. The great thing is this "gear box" can be retrofitted to earlier snow blowers AND it costs LESS than the price of a set of replacement sprockets and chain. It greatly simplifies the design and maintenance requirement for the snow blowers.

Do you have a part number for this and any install instructions. Would much appreciate it.
Thanks...Dave

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