Snowblower impeller shear pins keep breaking

[B2650man]

I have a B2650 tractor with a dealer installed, front mounted snowblower. The dealer supplied shear pins ( gold coloured ) for the impeller on the blower continually break ... even in light snow. We are not talking about particularly heavy or wet snow here, just your typical 2 to 4 inch snowfalls. And my driveway is paved and always clear of debris.

This has been going on for years. This past winter I went through dozens of impeller pins. I have read extensively on this issue and have had the dealer service and inspect the snowblower several times but cannot determine the cause of the problem. What is interesting is that the auger pins never fail, just the impeller pins in the drum.

I have always throttled back before engaging the blower and almost always engage in low gear. The only thing that seems to minimize shear pin failure on the impeller is to stay in low gear and maintain an extremely low throttle speed while blowing snow. As soon as I move to mine gear or up the throttle, the impeller pins break.

The only thing I can think is that the snowblower supplied by the dealer cannot handle anything more than a low throttle speed. But this doesn't seem right to me.

Wondering if anyone out there can offer any thoughts on what the problem might be?

 

[NoJacketRequired]

Not sure which blower you have. I have B2771, B2782 and B2550. On the B2771 and B2782 the AUGER takes a special bolt - you'll see it has a circumferential groove machined at both the head end and the thread end of the bolt grip. The IMPELLER takes a standard GRADE 5 bolt. Not grade 7 or 8, grade 5. I've double-checked this (ok, triple checked it) with all three of my local Kubota dealers to make sure I wasn't going to end up screwing up the gearbox. Since they all said the same thing I bought the Kubota-specific bolts for the auger and used my local fastener supply shop to source the Grade 5 bolts for the impeller.

Now for the rest of the story... I've used the B2782 hard this year - not with lots of snow but rather with lots of ice, thanks to recurring freeze/thaw cycles. I've waded into snowbanks that have been pushed up by the township plow, slop from the road that's full of gravel and frozen hard after it was pushed into place by the plow. No, I'm not proud to admit this is the kind of nonsense I've had to work with. I am pleased to say I have yet to break ANY shear bolts in this blower, or any of my Kubota blowers. (Knock on wood...) Get the right bolts in place and I'm pretty sure you will have a similar experience, unless you try to blow through your wood pile. Don't ask... 16" oak cord wood does NOT go through a snowblower!

 

[sheepfarmer]

I have a B2650 with the B2782B front snowblower, 2 years in use, and thank goodness have never broken a shear bolt. I got a bunch of spares, Grade 5, part númbers for the two kinds, 70060-00726 and 70060-01337 on good advice that they only break when your dealer is closed.

I start the snowblower when the tractor is at a standstill at close to idle speed. Then power up to pto 540, then advance forward into the snow. I do all my snowblowing in low gear because it is a lot of going around obstacles, gates etc.

It sounds like there is something odd about your machine if you can't run it at high rpm.

 

[Michigankubota]

The Land Pride rear blower I picked up has a PTO your shear bolt 8.8 grade metric and a grade 2 , 1/4 bolt for the auger. When I bought it the owner never noticed one of the aguger paddles was bent/ torn back. I had to heat it up ,bend it back and weld it. He never sheared a bolt. That said the 1/4 auger bolt should have broke first and it did not due to the fact he never greased the shaft which was partially seazed. So next the PTO shear bolt should have broke. The Farm King blowers use 2 grade 8 , 5/16 bolts on there PTOs.

 

[BAP]

What model is the snowblower?

 

[NoJacketRequired]

I have a B2650 with the B2782B front snowblower, 2 years in use, and thank goodness have never broken a shear bolt. I got a bunch of spares, Grade 5, part númbers for the two kinds, 70060-00726 and 70060-01337 on good advice that they only break when your dealer is closed.

I start the snowblower when the tractor is at a standstill at close to idle speed. Then power up to pto 540, then advance forward into the snow. I do all my snowblowing in low gear because it is a lot of going around obstacles, gates etc.

It sounds like there is something odd about your machine if you can't run it at high rpm.

I'll second Sheep's advice regarding starting the blower at low power, then letting things warm up before running up to PTO speed and advancing into the snow pile.

I once had picked up a piece of wire in the blower. Couldn't see it very easily, thanks to our limited hours of daylight here. Started the machine and heard just the faintest "different" noise. Shut down and found the wire wound around the end of the auger. There's no way I would have heard that at full power and who knows where that wire might have gone had I not discovered it.

Starting PTO-powered equipment with a bang is never a good practice, unless one enjoys replacing expensive parts!

 

[conropl]

Something is wrong with the blower. The OP says he throttles down before engaging and runs in low gear with 1"-2" of dryer snow on clean pavement. Even in those conditions he can not get to full throttle without breaking a shear bolt.

Not knowing which blower he has, it would seem there is something preventing impeller from turning (rubbing), or the dealer has supplied the wrong bolt for the blower model. Check your manual to make sure they are providing the correct shear bolt.

The reason I say rubbing could be a problem is because bearing and gear box binding problems are on the drive side of the shear bolt and would not put any strain on the shear bolt if they were binding. One possibility is your impeller is so out of balance or the bearing is so bad that as the speed increases the impeller deflects into the housing radially, along the front lip, or runs into the back wall. The other possibility would be bent shaft that would cause it to get worse as the speed goes up also.

As a point of reference. I had a BX2750D blower (50") and I would break auger shear bolts on occasion when wedging stones in it; but over the years, I would very seldom break an impeller shear bolt (and only when I ingested something large). And I always ran it at full throttle (as it is intended).

Full throttle is less likely to clog... so lower throttle may be making your loading problem worse. But since you can't get to full throttle it seems to be a mute point.

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[bearbait]

You need to have your dealer check it out, there is no way you should be breaking pins. I have a mile long gravel driveway and have never broken a pin so there is definitely something wrong with your blower.

 

[200mph]

Agree with the above statements about needing to verify the correct shear pin is being used. It would also help if you posted the specific snowblower model.

This is a long shot...
Also remember someone having a similar problem. The root cause in that case was the augers being out of time. The augers should feed the fan continuously, but if out of time they feed in a cyclic fashion. This causes high cyclic loading on the fan that may fail the shear pin prematurely. On some Kubota snowblowers there is a sticker inside the housing (upper right hand corner on B2781) showing the correct orientation of the augers. Not saying this is your problem, just it is a simple to visually confirm the augers are in the correct position.

 

[B2650man]

Thanks for your replies everyone, very much appreciated !

My blower is the B2782B mounted on my B2650 tractor. I have attached a picture of the impeller shear pins provided by the dealer.

Further to ... a few years back I had problems with this same blower and it was determined that the chain was incorrectly installed during the original assembly. The unit had to be taken apart and reassembled by the dealer. Not sure if this may have corrupted the unit internally but clearly something must be wrong with the mechanics if I cannot operate at high throttle speeds without continually breaking the impeller pins.

At this point I may investigate reaming out the impeller pin holes and installing a stronger bolt. I can't imagine this would damage the gearbox if I am only pushing light snow.

Cheers everyone !

 

[B2650man]

Thanks, indeed I did have this problem a few years back when I had to replace the one ( and only ) auger pin that broke on the blower. I had not oriented the augers correctly at the time but since learned of the correct positioning you have pointed out. But still, the snow chute seems to block too easily and of course when I raise the throttle speed the impeller pins become vulnerable to breakage. At a loss ...maybe it's the weight of our Newfoundland snow ...lol

 

[B2650man]

Thanks for your replies everyone, very much appreciated !

My blower is the B2782B mounted on my B2650 tractor. I have attached a picture of the impeller shear pins provided by the dealer.

Further to ... a few years back I had problems with this same blower and it was determined that the chain was incorrectly installed during the original assembly. The unit had to be taken apart and reassembled by the dealer. Not sure if this may have corrupted the unit internally but clearly something must be wrong with the mechanics if I cannot operate at high throttle speeds without continually breaking the impeller pins.

At this point I may investigate reaming out the impeller pin holes and installing a stronger bolt. I can't imagine this would damage the gearbox if I am only pushing light snow.

Cheers everyone !

I have a B2650 tractor with a dealer installed, front mounted snowblower. The dealer supplied shear pins ( gold coloured ) for the impeller on the blower continually break ... even in light snow. We are not talking about particularly heavy or wet snow here, just your typical 2 to 4 inch snowfalls. And my driveway is paved and always clear of debris.

This has been going on for years. This past winter I went through dozens of impeller pins. I have read extensively on this issue and have had the dealer service and inspect the snowblower several times but cannot determine the cause of the problem. What is interesting is that the auger pins never fail, just the impeller pins in the drum.

I have always throttled back before engaging the blower and almost always engage in low gear. The only thing that seems to minimize shear pin failure on the impeller is to stay in low gear and maintain an extremely low throttle speed while blowing snow. As soon as I move to mine gear or up the throttle, the impeller pins break.

The only thing I can think is that the snowblower supplied by the dealer cannot handle anything more than a low throttle speed. But this doesn't seem right to me.

Wondering if anyone out there can offer any thoughts on what the problem might be?

Not sure which blower you have. I have B2771, B2782 and B2550. On the B2771 and B2782 the AUGER takes a special bolt - you'll see it has a circumferential groove machined at both the head end and the thread end of the bolt grip. The IMPELLER takes a standard GRADE 5 bolt. Not grade 7 or 8, grade 5. I've double-checked this (ok, triple checked it) with all three of my local Kubota dealers to make sure I wasn't going to end up screwing up the gearbox. Since they all said the same thing I bought the Kubota-specific bolts for the auger and used my local fastener supply shop to source the Grade 5 bolts for the impeller.

Now for the rest of the story... I've used the B2782 hard this year - not with lots of snow but rather with lots of ice, thanks to recurring freeze/thaw cycles. I've waded into snowbanks that have been pushed up by the township plow, slop from the road that's full of gravel and frozen hard after it was pushed into place by the plow. No, I'm not proud to admit this is the kind of nonsense I've had to work with. I am pleased to say I have yet to break ANY shear bolts in this blower, or any of my Kubota blowers. (Knock on wood...) Get the right bolts in place and I'm pretty sure you will have a similar experience, unless you try to blow through your wood pile. Don't ask... 16" oak cord wood does NOT go through a snowblower!

 

[B2650man]

It's the B2782B

 

[BAP]

I wonder if at this point if you have broken enough shear bolts that the holes have become egged out slightly. I have seen that happen on equipment over time when I used to farm full time. We used to either ream the holes out to accept the next size bolt or replace the piece with the shear bolt hole. If the holes in the 2 pieces aren’t a fairly tight fit, that little bit of slack allows the bolt to shear too easy.

 

[B2650man]

I'll have a closer look to see if there is any play on the two alignment plates where the bolt is connected.

I'm wondering about the bolt. The dealer tells me they have provided me with a gold colored #8 bolt (not sure about this) for the impeller and an earlier post recommended #5 only. See pic attached.

I'm also wondering why there is no washer supplied on the gold coloured impeller pins yet the sliver auger pins have both a nut and a washer.

Perplexing for sure.

 

[B2650man]

I just re-read your reply. This is interesting. It appears that the dealer has been providing me with Grade 8 pins (gold coloured with 6 markings on the bolt head) for my impeller instead of Grade 5 pins - see pic. That said, I would have thought the grade 8's would be less likely to shear than the grade 5's.

 

[sagor]

I'll have a closer look to see if there is any play on the two alignment plates where the bolt is connected.

I'm wondering about the bolt. The dealer tells me they have provided me with a gold colored #8 bolt (not sure about this) for the impeller and an earlier post recommended #5 only. See pic attached.

I'm also wondering why there is no washer supplied on the gold coloured impeller pins yet the sliver auger pins have both a nut and a washer.

Perplexing for sure.

My though is that this bolt should have a lock washer, else vibration will cause the nut to come loose and eventually come off. Have you found any of the sheared bolts in the past? Were they actually sheared, or did they simply fall off?
The grade 8 bolt is a much higher strength than Gr5. Gr 8 has those 6 markings on the head. Don't mess with putting in a larger bolt, you will just break something else....
That all said, the parts manuals for B2782B show a Gr5 bolt for a shear for the fan. Putting in a Gr8 is already stressing something else.... Strange indeed...
EDIT: The parts manual also shows a "locking nut" on that bolt, so no lock washer needed. Be sure you are using a "locknut"
Also, the parts manual shows two different shear bolts, one thru the collar and shaft, the other just a shear bolt on the flange (on latest model). Some models may have different designs...

 

[Russell King]

Does it shear the pin at high RPM with no snow load on it? Like before you get going out of the garage into the snow it just will shear a pin if you throttle up? Or does it need a load and high RPM to shear?


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[B2650man]

Thanks. Interesting possibility re: Grade 8 vs Grade 5. I recently cracked off a pin in my PTO arm that connects to the blower. Had to pull off the arm and replace the pin. Maybe too much stress using the 8

 

[B2650man]

Good question and I see what you are getting at. The pin is breaking after engaging with the snow ... sometimes I get to clear the driveway with no hitches but most often, I end up having to replace the impeller pin over the course of 45 minutes. the quality and amount of snow do not seem to make a difference. I saw a video today of a farmer who advises using a very gentle forward motion at low throttle when engaging the PTO. This obviously makes sense but I would think Kubota implements would not be so delicate as to require such a soft touch.