Snow Attachments Shear pin dilema

[B7500Ray]

Hi Everyone; I have a Kubota B2781 51" snowblower and this year am eating the fan bolts to the tune of 1 every 15 minutes of use. The manual calls for a 1/4" x 1 1/4" grade 8 bolt and I have been using them,but am going mad changing bolts. any suggestions would be welcome.Thanks!!!

 

[grsthegreat]

man, a grade 8 for a shear bolt and its still breaking. i only used 1/2" grade 5's in my old blower. Are you hitting lots of rocks????

 

[dsmiley]

Are you running WOT? The reason I ask is that it's my opinion that the faster the fan is turning the greater the flywheel effect resulting in fewer sheared bolts. I have never read that but it seems right to me.

 

[sandyc]

I agree about wot or close to it. I run mine about 2200rpm and keep forward speed at medium and feather the hst pedal if the snow is too deep. I run the feet at half height as well.

 

[George2615]

A few things that can break shear bolts are engaging the PTO clutch too fast or at too high an RPM. Start at idle or close to idle speed RPM then slowly engage clutch to get PTO spinning then bring RPM up to operating speed.

Gravel driveways are very tough on shear pins. Gravel tends to stick to snow that is pulled into the augur. There isn't much space around the spinning augur and when a stone gets jammed and stops the augur there goes another shear bolt. One solution is to lower the skid shoes on the blower which raises higher it off the ground. Not so much of a problem on paved driveways. I have a gravel driveway and spent more time changing shear bolts than blowing snow. This is the reason I sold my snow blower and only plow now.

A shear bolt that is too loose or the wrong diameter can break prematurely.

Trying to blow snow at a speed faster than the blower can shoot it out can also cause the augur to get jammed up.

These are just a few suggestions that I'm sure you probably already know.

 

[Winmac]

Have you considered there may be something mechanically wrong with the blower.

 

[grsthegreat]

i have to say...my new blower doesnt use shear pins...and thats what helped sell me on it.

 

[dave1949]

You didn't have this problem in previous years?

Is your top link set short enough to keep the cutting edge below the auger out of the stones? Even with shoes down all the way, too much tilt to the rear will encourage the cutting edge to slice into gravel.

There is no clutch mechanism that unlinks the auger from the impeller fan, if the auger stops, the impeller stops quickly too, even if only momentarily. Quick impeller stops could cause shears just like quick starts.

 

[B7500Ray]

Thanks everyone!!I am running at 2100 RPM and rocks and gravel are not my problem. I suspect the bolts may be part of the problem [cheap imports maybe??]There is no contact between the fan and housing at all,but the flanges are perhaps not mating properly. I will look at that.Thanks!!

 

[dsmiley]

Ray, something I did on my BX2750D front blower which has back-mounted skids was to increase the size of the skid. The original was .25" thick and wouldn't stay adjusted so I added to it using UHMW plastic about 5/8" thick and long enough to go under the cutting edge. I went from shearing 6 fan bolts the first year to maybe 1 a year now. My road and my 3 driveways are gravel.


Dean

 

[ScottyChip]

Hi Ray, I have the same blower and I haven't broken a fan shear pin in over a couple of years. I also have a gravel driveway about 400 feet long, and I clear the snow out of the horse paddock when it gets to deep for him to move around. The times when I have broken the fan shear, fist sized rock gets past the auger, it's amazing how fast the blower comes to a stop when it gets jammed, and I sucked up a stack of sales flyers buried in the snow at the end of the drive, started to shred but then to much to handle, pop.
I have to agree Winmac, sounds like you may have a problem with the blower, can you rotate the augers easily by hand? Mine rotates quite easily by hand, is the gear box full of oil/grease? Do you start the blower at low rpm and the go to operating speed? This was my mistake first when I got my blower, but I only sheared auger pins, not the fan. You say you operate at 2100 rpm, for 540 on the PTO? I have to operate at 2600 with my B7510 to get 540 at the PTO, could it be it is operating to slow? Do you grease the PTO shaft, universals, augers and pillow bearings at the end of the auger shaft regularly? I grease my augers after I finish blowing snow, while the auger shaft is warm and easier to get grease in. Finally, I just purchased my replacement fan bolts at Princess Auto here in Canada, they seem to work fine.
I wish you all the best in solving this problem.

 

[B7500Ray]

Thanks Everyone for your help.I think my issue was the bolts I used, the unthreaded portion of the bolt was too short and were shearing within the threaded portion.
I blew out some of my paths yesterday, they were drifted in pretty good and I had no problems at all.Thanks Again,Ray