Snow Going through second stage bolts

[ruffdog]

That video is REALLY an eye opener. I'm just blown away how ignorant I was of the entire issue. Thanks to you and Dave for speaking up.

Yes, even at the slow speed it is running, it's amazing how much the speed varies on the output end twice every revolution. Can you imagine the torque variations running at full pto speed with a large snowblower impeller on one end? It's tough on the pto clutch, u-joints, splines, shear pins, etc....

 

[JWR]

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.

Hey Jrogers ! Take a look at http://www.tractorbynet.com/forums/...owblower-2.html?posted=1&posted=1#post4668190 This guy (using a RAD front mount blower on a Massey about the size of your Kubota) has been breaking pins right and left. Very possibly the same blower adapted to Kubota in your case and Massey in his case. Look at what the guy in post #17 says in that thread. Basically the top sprocket on the side gets loose and begins jerking on the shaft. Eventually it breaks the Woodruff Key on the sprocket shaft but in getting there goes thru a potload of shear pins elsewhere in the drive due to the jerking. Don't think anyone over on this side (in this Kubota thread) has mentioned that possibility.

 

[Jay4200]

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.

I've only broken shear bolts a few times in many years of annual use. Once I sucked up a boulder out in the road, but the other times were from cutting the throttle before the blower was completely cleared of snow - whole thing packs up and 'tink' tink' 'tink' - they all break. Perhaps you're not keeping the RPMs up high enough to keep the snow flying inside the blower. Do you run at full WFO when running, 'cause you need to.

 

[ruffdog]

Here is another thread about phasing with very good videos.
Viewing a thread - Drive shaft trainer video.

 

[Dave M7040]

Look at these two photos which another poster put up on another thread.

There is clearly a design change to solve the breaking of the shear bolts.

The bolt in the new design located where the former shear bolt was is now a solid bolt and the shear bolt is out to the side.
Sure looks like the company was experiencing lots of problems

Dave M7040

 

[JWR]

Yep, Dave is right and I think the dealers and/or RAD as the OEM owe the users a recall and retrofit.

 

[Dave M7040]

Yep, Dave is right and I think the dealers and/or RAD as the OEM owe the users a recall and retrofit.

JWR

I have just sent the following email to Rad.

It will be interesting to see if they will reply to the public.

Perhaps many people should be emailing RAD.

Dave M7040


To: radinter@radinter.com
Your company, who appears to make blowers for various tractor manufacturers, has produced a product being repeatedly talked about on tractor forums for having excessive shear bolt failures under normal operation.

Now we have discovered, quite by accident, that a design change or update appears to have been done.

I have posted pictures of the shear bolt details at the fan hub showing the difference.

Can you advise if this is a product upgrade available to customers who are having to change 5 or 6 shear bolts when blowing snow on their own property with no sign of any obstruction such as a rock which could have caused the failure.

David Petepiece P. Eng.

 

[Jay4200]

Any resolution yet? The shaft phasing thing is interesting - the Kubota front mount blowers have primary drive shafts that just plop apart, unlike the 3pt shafts that run the big boys in the back, so you do have to put the together correctly - can't remember if they have alignment splines or something. You'd think they would if this was a big issue. Now I'm going to have to remember this in case I ever run my BX blower.

 

[aczlan]

Any resolution yet? The shaft phasing thing is interesting - the Kubota front mount blowers have primary drive shafts that just plop apart, unlike the 3pt shafts that run the big boys in the back, so you do have to put the together correctly - can't remember if they have alignment splines or something. You'd think they would if this was a big issue. Now I'm going to have to remember this in case I ever run my BX blower.

Can you look on yours to see if it is square or rectangular? If it is rectangular it will keep the phasing correct.
The mower shaft on our BX2660 is splined but there is a bead of weld between two of the splines so it only goes on one way.

Aaron Z

 

[ruffdog]

Other than phasing, the 2 u-joints should be at the same angles too.

 

[JWR]

Ruffdog: I'll pick your nit just a little: The only way 2 u-joints on the ends of a common shaft can have the same angle is when the two external shafts they connect (e.g. the driving shaft and snowblower input shaft) share a common direction. And, when they share a common direction, the 2 u-joints will automatically be at the same angles. There aren't any other choices. With a snowblower it is a noble goal to keep the two shafts aligned in a common direction; have the tractor / blower combo support that goal. But you also have to have the flexibility to set the blower angle relative to the ground and there will probably be a small difference in the u-joint angles. That's not a significant issue (and besides you have no choice.)

 

[ruffdog]

I have seen people run a tiller or blower NOT level to the ground. They claim it runs better either tilted toward the front or back for some reason. Yes, NORMALLY, the joints are at the same angle running a implement on a 3PH.

 

[jrogers]

Sorry for the delay in getting back to all of you. I am still having the same problem. If anything, it is more based on the amount of time that it runs between failures than the material I am moving. It might run for 45 minutes to an hour before it breaks. I was not aware of this phasing issue, and I am pretty sure mine has a square slip shaft with no key in it. Based on a google search, it seems like there are 2 'OK' positions and two 'bad' positions to choose when putting the shafts together?, right?

Universal Joint operation, U-joint Phasing sketch, Airheads, Paralever Driveshaft, K bikes


I am torquing the shear bold to maybe 10ft lbs. I have varied it a bit, and nothing seems to make a different. Fit in the hole is pretty tight, so I don't think this is the issue.

At this point this phasing thing seems like a reasonable thing to look into. I will post more later.

Thanks!

 

[jrogers]

Look at these two photos which another poster put up on another thread.

There is clearly a design change to solve the breaking of the shear bolts.

The bolt in the new design located where the former shear bolt was is now a solid bolt and the shear bolt is out to the side.
Sure looks like the company was experiencing lots of problems

Dave M7040

Just to clarify, my shear bolt is the bolt that he has labeled as Shear Bolt. Apparently mine came with this mod, since it is all orange.

 

[jrogers]

Also, I am running my blower at PTO Speed (not a slower speed). I do throttle it down when I engage it, but them throttle up before blowing snow. Failure is happening at light load on the motor and not a heavy snow load or when blowing debris.

 

[jrogers]

...But if all else fails, and it keeps shearing that often, it becomes better use of your time to just buy a slip clutch and be done with it.

I don't know what a slip clutch is. Can you explain this further?

 

[PILOON]

If the blower is like shown in post 54, drill out the hole and go next oversize, eg go from 1/4" to 5/16" and use grade 5 or better bolts.
Soft bolts will bend B4 shearing and gall the holes and actually stretch somewhat while graded will shear clean but only on sudden impacts.
Soft shear bolts become a bugger to drive out while graded pop out easily.

Soft bolts will stretch and weaken gradually while graded will only fail on sudden impacts.
The holes want to be sharp as they actually act like a shear.

I learned the hard way having once, in a bind, used a 4" nail instead of a 1/4" bolt, that resulted in galled holes so I reamed out the holes and went next size up and used graded bolts with lock nuts.(not torqued, just snug)
Now I only shear if I digest a stone or some other hard object and the shear bolts are no problem to remove, in fact they simply drop out on their own.

 

[jrogers]

One other thought, make sure the front impellers are opposite on the shaft. If they aren't 180 degrees from each other they may be jamming too much snow in the impeller.

Thanks for the suggestion. I went into the dealer the other day and they said the same thing. I checked, and I do have the right and left augers 180 degrees out of phase so they are not overloading the fan.

 

[jrogers]

If the blower is like shown in post 54, drill out the hole and go next oversize, eg go from 1/4" to 5/16" and use grade 5 or better bolts.
Soft bolts will bend B4 shearing and gall the holes and actually stretch somewhat while graded will shear clean but only on sudden impacts.
Soft shear bolts become a bugger to drive out while graded pop out easily.
I'd start with grade 5.

I am currently using Kubota dealer shear bolts, and I would like to resolve the issue without over-sizing or moving to a different bolt. I am encouraged by others comments that the blower can handle sand and gravel, so I will put some effort into this, looking at the universal alignment as well as the gearbox. I do remove the blower each year by sliding the shaft out and was unaware of the phasing issue, so this is a good place to look.

 

[PILOON]

Oh yes, sand and gravel, so much so that I have no paint on fan, chute or augers after 2 snow storms.
Since fancy paint job is useless I simply spray the shiny paintless surfaces in the spring with a rattle can simply to prevent rust, in fact I don't even color match but even the thinnest paint (rattle can) will prevent rust.
Notice that in winter the metal remains shiny and rust only forms over the hot summer days.
Snow sticks to rust but not shiny metal as well.
For sure the phasing helps as it feeds the fan more evenly.
Buying dealer shear bolts is $$ down the drain IMHO.