Snow Blower Frustration!

[RidgeHiker]

I have a 72" Woodmaxx snow blower on my 50 hp Kioti. Just broke another shear bolt. I have used regular snow blowers for years but this is my first tractor snowblower and do not know if I just do not understand it's capabilities or is there some other issue. Another way of asking is it me or the snow blower (or both)?

We have about 14" of new snow, not real heavy nor light. About 12"-16". Last night I hand shoveled out the entry area to my house and piled it into the driveway area. Maybe 2.5" high at peak. Pile was somewhat compressed from shoveling and sitting. Probably 1/2 the snow blower width was into it and rest into untouched snow. Shear pin died. Snow was packed into the auger blades and the impeller. Not like concrete but in there. I assume either I am expecting more out of the blower than is realistic or shear pins are too weak though I am using recommended ones, grade 5.

Feedback from more experienced users would be much appreciated. Thanks in advance for your assistance. Going to go out now and replace the bolt.

 

[RNeumann]

Sounds like the shear pins are doing their job. The only thing that can cause issues on a new (properly functioning- no internal binding etc) blower is improper driveshaft length or angle. With the machine off and PTO in neutral does everything spin freely- both on the ground and up 6” or so.
If that’s not the case...time to slow down

 

[aczlan]

Which shear bolt, the PTO one, or the auger one?

Any pictures of the sheared bolt pieces?

Aaron Z

 

[RidgeHiker]

Couple other elements to mention. Love the tractor but would like to have a lower low range 1st gear. Probably would work better if I could go a little slower. Also, noticed that the PTO shaft is at least some times rubbing on the bottom corner of the upper horizontal bar of the quick attach. There is a couple inches clearance with it sitting on the ground now but is either bouncing or pushing together. I have adjusted the upper 3 point arm to create a little more space. Will see how that works.

 

[ruffdog]

This happens more often early in the season as snow sticks to warm metal, then freezes to it. Then, snow continues to stick to the rough surface until it plugs. Try spraying the inside of the blower with your favorite cooking spray or lube.

 

[Captain Dirty]

I have a 72" Woodmaxx snow blower on my 50 hp Kioti. . . . I assume either I am expecting more out of the blower than is realistic or shear pins are too weak though I am using recommended ones, grade 5.

Be thankful the shear pins are failing rather than something more expensive.

Does the Woodmax owner's manual specify an SAE size, grade 5 bolt? I Googled "Woodmax snowblower shear pins; Woodmax sells M6 x 35mm auger shear bolts, but does not mention the grade or show the face of the bolt head. The PTO shear bolts are non-standard with no specs.

My Italian Goldoni snowblower (10 HP) uses M6 grade 12.9 (176,900psi) shear bolts; my American Lorenz (max 40 HP) uses 1/4-20 grade 5 (120,000psi) shear bolts. (Grade 8 is 150,000psi.). The M6 bolts shear at a spot closer to the axis of the shaft than the 1/4" bolts, and I trust the engineers knew what they were doing. Https://www.engineeringtoolbox.com/steel-bolts-sae-grades-d_1426.html gives the specs for SAE bolts and a link to metric bolts.

Couple other elements to mention. Love the tractor but would like to have a lower low range 1st gear. Probably would work better if I could go a little slower.

Once you have the initial pass, you can adjust the input volume/weight of snow to ground speed by taking less than a full width pass. For the initial pass you may have to advance, stop to let the blower clear itself, and then advance again. Experience will teach you.

 

[aczlan]

Does the Woodmax owner's manual specify an SAE size, grade 5 bolt? I Googled "Woodmax snowblower shear pins; Woodmax sells M6 x 35mm auger shear bolts, but does not mention the grade or show the face of the bolt head. The PTO shear bolts are non-standard with no specs.

Post #3 has a screenshot of the shear bolt page in the manual. They call for a standard 2.25" long 5/16" diameter grade 5 fine thread bolt for the PTO shear pin.

Aaron Z

 

[leonz]

Couple other elements to mention. Love the tractor but would like to have a lower low range 1st gear. Probably would work better if I could go a little slower. Also, noticed that the PTO shaft is at least some times rubbing on the bottom corner of the upper horizontal bar of the quick attach. There is a couple inches clearance with it sitting on the ground now but is either bouncing or pushing together. I have adjusted the upper 3 point arm to create a little more space. Will see how that works.

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If the lower links are not fully extended(if possible) the propeller shaft will be shorter and can rub on the quick hitch cross member.

 

[Captain Dirty]

I just went back and enlarged aczian's attachment (comment #3). On page 24 the caption on the lower left picture states there are six 1/4" holes in the flanges on the augers. The "note" states the machine comes with two M6 grade 8.8 bolts [116000 psi so grade 5 (120000 psi) for practical purposes] but these may be substituted with two or three "1/4" x 18 x 1-1/2" bolts". One-quarter inch = 6.3 mm so grade 5 1/4" bolts would be stronger than grade 8.8 M6 bolts; 3 of them would obviously be stronger than the 2 original bolts. SAE 1/4" bolts are usually 20 TPI (coarse) or 28 TPI (fine); 5/16" bolts are 18 TPI (coarse). This may be a typo, but that and the lack of a grade spec for the substitution gives me pause. You might e-mail Woodmax for confirmation and to have something in hand if there is a warranty issue.

 

[aczlan]

Good catch Captain Dirty, I suspect that someone copied the PTO shear pin spec to the auger shear pin spec and just changed the bolt size to 1/4".

Aaron Z