Snow Going through second stage bolts

[jrogers]

Another thread about the shear bolts:
http://www.tractorbynet.com/forums/kubota-owning-operating/233449-kubota-bx-2750d-snow-blower.html

Helpful thread, thank you. The two things I got out of it were torque to 9ft-lbs and MB Tractor and Equipment | The Best Tractors and Equipment on Earth (R)

70060-01074 $.85
70060-01337 $1.95

Where I will order some additional spares. I am suspecting that the 'traction sand' may be the problem for me. I am guessing that it is getting in the edge of the fan blades and binding things up.

 

[jrogers]

Helpful thread, thank you. The two things I got out of it were torque to 9ft-lbs and MB Tractor and Equipment | The Best Tractors and Equipment on Earth (R)

70060-01074 $.85
70060-01337 $1.95

Where I will order some additional spares. I am suspecting that the 'traction sand' may be the problem for me. I am guessing that it is getting in the edge of the fan blades and binding things up.

Not much cost savings, the ground shipping costs as much as my order, so about the same price as the dealer.

 

[jrogers]

Still shearing bolts. I am thinking that the size of the sand/gravel they use on the roads is close to the gap between the impeller and the housing (maybe 3/16"?). They pour a lot of this course sand on the main road, so I am trying to back blade this off and not get it in the blower, but still averaging a shear every other time plowing, even in light dry snow. Not sure where to go from here, but it really adds to the plow time to stop and put in a new bolt.

 

[dsmiley]

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 never seen this written anywhere but I believe that the fan running at wide open throttle (like the manual recommends) creates a flywheel effect allowing it to blow through small rocks, etc without shearing bolts. If you aren't running WOT, try it like sandyc suggests. If you are running WOT then I would be looking at bent shafts, misaligned gears, or chain problems.

 

[ruffdog]

Or at least run it at the correct pto speed. What speed is the OP running at?

 

[Dave M7040]

jrogers
Could you please post a couple of pictures of the pto shaft between the tractor and the blower including where the shear bolt that keeps failing is located.

Something basic is wrong and being overlooked.

Is the failing shear bolt part #19 in this exploded pa.rts illustration?

I am wondering if the pto shaft is not telescoping properly when the blower is raised and lowered.
The hydraulic cylinder would easily side the two parts of the pto assembly and shear the bolt like a bolt cutter.

Has this possibility been investigated. Pto shafts often need to be cut a bit shorter so they are not fully compressed at any point in the tractor operation.


Dave M7040

 

[sandyc]

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.

 

[JWR]

I re-read this whole thread and have to agree with DaveM7040 -- Something basic is wrong and being overlooked. You indicated that:
1) This happens all the time,nearly every time you blow snow.
2) It also happens in dry fluffy as well as heavy wet, yet it breaks when things are getting heavily loaded with snow.
3) The rotor spins freely when the shear pin is out.
I just can't see sand or gravel being any different for you than many other folks. Agree with those saying to use wide-open engine speed. But most or all of the things mentioned are marginal and not going to cause the constant failure rate you are seeing. SOMETHING AIN'T RIGHT HERE. A couple more questions: Any chance the unit has a lot of hours on it and the shear has occurred so many times that the bolt hole is worn out to larger size ? If so, drill it out and go to a slightly larger shear bolt. Maybe some of the rotor bearings are worn out and bind under load ? Have any of the parts/shafts/sleeves been replaced in the life of the unit ? Maybe something is not quite right sized ? I still say -- get to the bottom of the cause first. 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.

 

[07wingnut]

If it indeed is the gravel that is causing the fan bolts to shear, try closing up the fan/fan housing gap by installing some type of flap on the end of each impeller. There are plenty of threads of people doing this to increase snow blowing distance, but the other side effect is that small rocks are swept up and blown, rather than jamming the fan. I have done this on a 2750D and it helps. Lots of gravel gets blown off my driveway each snowfall, but shear pin breakage has dropped to just once in a while.

 

[JerryK]

I'm with JWR. Something basic is wrong. Maybe you are tightening the shear bolts that puts extra stress on them from the get go. Something binding, or PTO engagement at high RPM or engagement too snappy. All the blowers I have ever used could care less if they are blowing snow or gravel... I've had trouble with a couple big 6-8" rocks... but gravel just robs HP, wears down the inside of the fan cavity, and makes lots of noise...