Why do I keep breaking shear bolts on my snowblower.......

[KanakaRick]

I just went through this with my new Woodmaxx blower. What I found:

1. The direction of the driveshaft makes a difference (I had it on upside down).

2. My toplink moves too quickly (I need to put a flow porportioner on it) and the jerky movements instantly snap the shear bolts. I have to teach myself the NEW proceedure if I want to adjust the blower:

a. Idle Down
b. Turn PTO off
c. adjust equipment
d. Turn PTO on
e. Idle up

 

[cathy liebchen]

how about using a slip clutch? I don't know if they work on a snow blower, we don't have them here

 

[Saitcho]

If I was to add a slip clutch do I get rid of the shear bolt?
Is there an adjustment to make on a slip clutch, or are all the cat1 slip clutch the same?

 

[leonz]

BonJour Saitcho,

Mon Ami, we have all been there with the frustrations of snow clearing when
the snow is deep and heavy.

The use of a compression spring type contact flange or the direct contact
flange slip clutch is not required or needed with a snow caster like yours as
the shear bolts are a much more efficient fail safe mechanism.

The thing you need to know is that snow pack that has gone through a
freeze thaw cycle just like your snow pack can and will cause a huge
amount of resistance that will stop the snow caster from working.

Have you checked the roller chain drive system on your snow caster?

Can you take a partial cut of snow off your snow pack if you have room to move?
If you can; it would be best to raise the snow caster a few inches to allow the snow
caster to take a partial bite in a half cut at an angle to shear off the snow pack
a little at a time.

If you have a loader on your mule you can scoop a little snow off the side and
then dump it and do that from one end to the other of the lane and then use
the snow caster to clear off the broken chunks of snow.

SO much of the frustration in dealing with snow pack is the fact that the cross
augers do not have serrations to cut the snow as it enters the snow pack and
it pushes it forward and as result it reduces snow caster ability to clear snow.

 

[Saitcho]

What frustrate me the most is at one point I am chewing thru old frozen stuff that make a **** of a racket in the auger with no issue and 10 minutes later I am working in fluffy stuff and the bolt break. I keep looking for piece of wood or rock or ice chunks and I can never find out what caused the pin to break. The total randomness of the situation is what puzzle me the most. I broke 5 bolts on the last storm and none on the previous one. Snow condition was pretty similar. The first time I used the snowblower I did not have time to box blade the road so there was alot of rocks. I was throwing tennis ball size rocks 20 feets in front of the snowblower and never broke a single bolt. My father finally broke the original bolt when he engaged the snowblower at full rpm. Since then its always hit and miss sometimes I can get 4-5 hours per bolt sometimes 5-10 minutes. I checked chain tension and I gave it a bit more, I dont think that was the issue. I also have a chain shear bolt that never broke.

 

[Reb954]

Which shear bolt is shearing, the one for the auger or on the main driveline?

How old is the blower?

Check for looseness in the auger bearings just to be sure you don't have a bearing going bad.

 

[ruffdog]

Check to make sure your PTO shaft joints are in phase. If they are not, your impeller is rapidly forced to speed up and slow down.

 

[Saitcho]

Im pretty new to the world of tractor and didnt knew about the PTO phasing things. I will take a look into that. The snowblower and the tractor are 2 years old. The bolt that always shear is the one on the main PTO drive line. This afternoon I am going back at it with new shear bolts. I can fit 1/4 and M6 bolts in there. The 1/4 is 0.250 inch obviously and the M6 are 0.236 inch. Looking back at the old bolt I have, the dealer gave me 1/4 grade 5 bolts. This time dealer sold me M6 grade 10.9 wich is stronger than the 1/4-20 ones. Manual says this: (For the PTO shaft, always use a grade 8.8 shear bolt at 540 RPM.) Should I always run the tractor at 540Rpm pto speed or is it ok to vary the speed according to conditions?

 

[Reb954]

Always run the blower at its rated rpm, otherwise snow will tend to stack in the blower. That may be why you are shearing pins.

Vary the speed of the tractor for the conditions.

 

[Saitcho]

Today I was chewing thru old stuff like it was butter and not a single broken bolt. I removed the last shear bolt I was using and found it loose..... It was the same size and grade as the new one I bought but the new oner are golden and the previous one was black. I added some locktite this time. I found the snowblower was tilted to the rear so I brought it back to horizontal. I ran the tractor at max speed and went at it with no issue. I checked the PTO phasing and it looked good. Half-way thru my run I stopped and was able to retorque the shear pin. My guess is the bolt kept on loosening and since they are a bit smaller than the hole they where shaking themself to death in there. Thanks for all the ones who chimed on this thread I learned alot from you guys. With all the snow gone this mean more time for snowmobile tomorrow!!!!