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I have a JD59 inch snowblower on a 3720. Last storm a rock caught between the 2nd stage impeller and the housing an stalled out the tractor (instant dead stop). On our JD47 inch snowblower on the 445 there is a shear pin on the impeller and the ends of the augers. It looks like the 59 inch only has shear pins on the auger ends.

Is that correct? I'd rather break a shear pin than stalling the tractor. Any recommendations?
 

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According to the operator's manual the only sheer bolts are the two on the auger. Looking at the parts diagram I thought perhaps #13 might be a sheer bolt but key #14 would defeat the purpose.

59_impeller.jpg
 

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Shear bolt and key is used on the 59.

Be careful with the bolt, if you crack the housing your wallet will be empty after you fought through replacing the bolt and key only to have it shear again.
 

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I have had similar problems with both the Model 47 and Model 59 blowers. These are identical units except for the longer augers on the model 59. Same gearbox, impellors and auger drive.

Anyway, i used to run both the key (#14) and bolt (#13), but would break the bolt, and then the only thing holding things together was the key. But it would stress the universal joint (#11), and crack it. They are normally $275, but on the last one, I was able to get te frequent buyer discount and bought it for $250! YAY!:banghead:

When I replaced everything, I deleted the key and used only the bolt. But then I started having problems with the bolt breaking too frequently. The bolt is a 5/16 x 2 Grade 5. The problem was that the bolt threads were within the area where the shaft and hub come together causing a weak point. Solved the problem by installing a 5/16 x 3 bolt that I cut back to about 2 1/4" long. This longer bolt has a longer shoulder to the point where the threads start inside the hub. You can't snug the bolt to the hub, but that's not critical. It is better than replacing the bolt frequently, or replacing the universal joint even once if you haven't yet.

Dave
 

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I have had similar problems with both the Model 47 and Model 59 blowers. These are identical units except for the longer augers on the model 59. Same gearbox, impellors and auger drive.
that's true if you owned the 47 blower with rear gearcase drive, but not true for the rear chain drive units that are for quick hitches.

i believe OP was referring to a quick hitch version (on a 445), which has 3 shear bolts, 2 on outer auger drive hubs,
and another similar hub to drive impeller.

the gearcase drive 47 blowers, are similar to the 59, but they aren't very common now,
there may still be some out there for the front mount mowers but it's not put on the quick hitches for x7/1R and older 2 series cuts.

that old 47 blower was used on the old 400 tractors, 318 etc. when in use on front mowers, the gearcase reverses the drive from
what is used on the front of garden tractors as those units drive in the opposite direction
 

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The gear case for my f-911 was exactly the same as one for a 420/430 and also a 59 for CUTs. There was no reversing.

So far everyone has been discussing the chest freezer version, not the quick hitch if there was any confusion.
 

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I believe that with the original Deere design, the purpose of the #13 bolt was to locate the impeller and impeller hub on the gearbox stub shaft so the impellor doesn't run into the housing. The key transmits the rotaional torque to the impeller. The flaw in the design is that if the bolt breaks, the keyway is the only thing holding everything together, and that doesn't bode well for the impeller hub at $275.

With just the bolt, if you catch a rock, the bolt should fail first.

Dave
 

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The gear case for my f-911 was exactly the same as one for a 420/430 and also a 59 for CUTs. There was no reversing.

So far everyone has been discussing the chest freezer version, not the quick hitch if there was any confusion.
maybe the difference was with the compact tractors... i know they make 2 different gearcases for those blowers depending on
application, with the difference being output rotation via an extra gear in the case
 

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maybe the difference was with the compact tractors... i know they make 2 different gearcases for those blowers depending on
application, with the difference being output rotation via an extra gear in the case
I have heard that too, and also about a reverser additional box but I’ve yet to actually see one, or a diagram.

The 300 series gearbox has a different ratio that would overdrive blower.
 

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I have heard that too, and also about a reverser additional box but I’ve yet to actually see one, or a diagram.

The 300 series gearbox has a different ratio that would overdrive blower.
2 different gear case pictures, note the number of gears inside, 2 vs 3
420.jpg

1145.jpg
 

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Discussion Starter #11
Thanks for all the replies. The 47 I have is a different setup than the 59. 3 shear pins on the 47 and only the 2 on the 59. I’ll look at removing the key when we take it apart for paint this summer.
 
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