Snow Going through second stage bolts

[jrogers]

On my first plow of the year I went through a couple of second stage bolts on my Kubota snowblower. I thought it was from the wet snow, but today we had 6 inches of dry snow, and I went through 3 more. I did not see that I was hitting anything, it seemed like if I even loaded it up much they broke. Any suggestions on how to deal with this, short of putting a non-shear bolt in? Can this be a symptom of something else wrong with the blower? Is it better to torque the shear bolts really tight, or just snug for maximum torque before breaking? Any help is appreciated.

 

[oosik]

When I had a snowblower the first time I would use it, each winter, would always "cost" a couple shear bolts. It was always from rocks getting jammed in the fan. I found that being in my open station tractor - I would always hear whatever caused the bolt to shear as it hit the fan.

Something on your blower is wrong OR you may need a tougher shear bolt. I'm not quite sure what you mean by "second stage shear bolt". Explain

BEFORE you go to a tougher shear bolt - drop into your Kubota dealer and see if he can figure it out.

I always used grade 2 - regular old hardware store bolts on my blower. I always tightened them down pretty good - so there was no possible slop at the bolt location.

BTW - I lived in Anchorage - - 1965 thru 1982.

 

[AStanton]

I had a problem with bolts shearing on my 3-pt hitch blower 2 years back during a heavy snow season. What I found was the pto shaft wasn't freely sliding in and out. Check yours. If it's not sliding freely, get some spray lube in there like Fluid Film. I was using white lithium spray grease and it gummed up the action.

 

[Dave M7040]

On my first plow of the year I went through a couple of second stage bolts on my Kubota snowblower. I thought it was from the wet snow, but today we had 6 inches of dry snow, and I went through 3 more. I did not see that I was hitting anything, it seemed like if I even loaded it up much they broke. Any suggestions on how to deal with this, short of putting a non-shear bolt in? Can this be a symptom of something else wrong with the blower? Is it better to torque the shear bolts really tight, or just snug for maximum torque before breaking? Any help is appreciated.

By second stage do you mean the shear bolt protecting the auger which feeds the snow to the fan?
Are you using SAE bolts ( American thread) which fit the hole or the possibly correct metric bolts. A small increase in the diameter can increase the strength significantly.
Could you post a picture of the bolt you are using. One photo of the head of the bolt and another shot of the side of the whole bolt.

Dave M7040

 

[JWR]

All the questions about "Which shear bolt do you mean?" are good ones. One thing I have found with shear bolts in other applications (tillers, small bush hogs, etc.) is that the bolt must exactly fit the hole. Almost force fit. English instead of metric is bad, etc. If there is the slightest bit of slop in the hole that the shear bolt goes in it will shear in very little time.

 

[sandyc]

Run wot and that should help. Slower rpms can put stress on the bolts

 

[jrogers]

When I said second stage, I meant not the auger but the fan (the vertical section). I rarely shear the auger bolts. The bolts I have been getting are from the Kubota dealer, so I am assuming that they are giving me the right thing. We have had some warming and cooling, so the driveway has had some 'traction sand' put on it, which has some coarser sized pebbles in it that may be causing the issue, maybe a 1/4" in diameter. Thanks for the advice on running the blower at full speed as well as torquing the bolts tight, those are both things that I have been wondering about. I took the time today and greased all of the fittings on the blower. It probably won't help but certainly won't hurt.

So do you think the traction sand could be the issue, and do you think a finer sand would cause less issues?

Thanks for all of the replys.

 

[ruffdog]

1/4 inch is .250" and 6mm is .236"

 

[Dave M7040]

When I said second stage, I meant not the auger but the fan (the vertical section). I rarely shear the auger bolts. The bolts I have been getting are from the Kubota dealer, so I am assuming that they are giving me the right thing. We have had some warming and cooling, so the driveway has had some 'traction sand' put on it, which has some coarser sized pebbles in it that may be causing the issue, maybe a 1/4" in diameter. Thanks for the advice on running the blower at full speed as well as torquing the bolts tight, those are both things that I have been wondering about. I took the time today and greased all of the fittings on the blower. It probably won't help but certainly won't hurt.

So do you think the traction sand could be the issue, and do you think a finer sand would cause less issues?

Thanks for all of the replys.

You should be able to blow lawn sod through your blower so sand is not going to be the problem. Typically shear bolts break when you "find" that concrete block you forgot to move buried in the snow and you try and blow it.

How about a model number of your blower and is it front or rear mounted.

If rear mounted, is your pto multiple speeds and what speed are you running it at?

The rear mount blowers I have experience with have a total of two shear bolts one on the pto shaft which protects everything but especially the fan and a second on the auger. Your description makes me think your blower is front mounted. Is it?

Do you have a manual for your blower and if so what does it state about shear bolt specifications?

Dealer parts guys are not infallible when it comes to giving you the correct shear bolt for the blower you have. Did he look up a part number or just grab one from a bin? do you have an invoice with a part number on it?

This has to be a problem with a simple solution.

Dave M7040

 

[JWR]

I have been running a 5ft Agro-Trend 3pt mounted snowblower for 20 years. I don't use it many times per year but when I do it is usually rough and a workout in heavy snow. In mountains of WV. I can recall throwing large gravel accidentally for long distances, picking up chunks of ice that went through the blower sounding like a bush hog that just hit a 2x4. I drive it with a 24hp Kubota B2150. I have never replaced the original shear bolt. Never a problem (yet...) So I have to wonder what on earth is wrong with your rig. I've never owned a Kubota brand snowblower but I heard they are made in Quebec for Kubota by a company with a pretty solid reputation. What you describe is just not right -- something is haywire. The shear bolt must fit very snug/tight and cannot have any play in the hole. Go read the manual and don't count on the dealer to give you the right shear bolt. Does the rotor turn fairly easily by hand (when the tractor is shut off) and not seem to be catching on something or wobbling ? By the way, shear bolts are normally intended to break when excessive loads occur and are NOT normally high grade bolts. Plain old grade 2 usually. I would not go putting in a super strong bolt until I figure out what the problem is. The manual should tell you what grade bolt to use. Checked the lube in the gearbox ? ... Let us know what you find !