Why break chain on snowblower?

[bialecki]

A Grade 2 bolt, (obtained at any hardware store or TSC, etc.) has a lower tensile strength and is acceptable for a "Shear Bolt". A grade 5 is hardened, hence, a higher tensile strength and will not shear as easily as a Grade 2, possibly causing damage to another component of the machine when a stone gets jammed in the auger of a snow blower.

 

[dutchman56]

true and I agree, but why does Kubota spec grade 5?

 

[KubotaOne]

I've had my share of blower chains breaking. I'm going into my third winter with my B3030 front mount blower, and I just broke a third chain yesterday.

I've made sure the sprockets are aligned, I've tensioned the chain to spec and I've lubricated the chain regularly. Shear bolts are all factory grade 5, as per the manual. The first chain I broke I thought was due to improper tension - too tight. It made excessive noise and a "whurring" sound. That chain lasted about a half hour after it's first use. My dealer came out and installed a new chain (now I realize it was a lesser quality, one that they had in stock, plus it was not an "O" ring type) That lasted about a month - the rollers were completely destroyed.

So, I thought I'll buy a new, Kubota Chain - it's an "0" ring type, and is not cheap. Again, checked sprocket alignment, tension and lubed. After about 4 hours of use in total, it broke yesterday.

My understanding is that what's most likely to cause the breakage is improper sprocket alignment. Hitting a rock or sucking in a newspaper will break a shear bolt. I've never broken a shear bolt yet. I've tried several other things as well over the last couple of years (do a search for my name and key in "blower" for more)

Frankly, I'm at a loss.

 

[dutchman56]

I am going to check alignment better next time up at camp and I think I will try some grade 2. Chain is 60HD and not roller and I bought 10 foor box for spare and 1/2 dozen connecting links. But hopefully grade 2 will break and then can fix on road in a few minutes instead of driving back maybe a couple of km to garage to fix chain instead of fighting it in snow.

 

[StrangeRanger]

Go w/ grade 2 bolts. You may end up breaking them more often, but they're a lot cheaper and easier to fix.
When blowing snow I've got my ratchet, 2 sockets and wrench in one pocket and the other pocket is filled w/ the 3 sizes of grade 2 bolts and lock nuts that I need. Just wish I didn't need to keep track of 3 different sizes
j

 

[KubotaOne]

No offense, but... changing to a "weaker" shear bolt still does not explain why the chain is breaking. It's a heavy, strong chain, it shouldn't break, period. Going to a lighter shear bolt would only make me have to start changing them.

I'm convinced the problem is not the shear bolts, heck, you could put case hardened grade 8 bolts in there, and they would still shear before that big heavy chain would snap.

There's something else that's causing this.

 

[TGD]

Could it be possible that under a load the auger is forcing it's shaft to one side (side to side play) or the other causing a mis-alignment of the sprockets and breaking the chain?

 

[rbargeron]

Another suggestion would be to inspect the teeth on the sprockets - there could be damaged teeth somewhere. A couple teeth could be deformed so they sometimes catch the side links of the chain and jam, snapping the chain. Another thing to look at is whether the chain is really the right one for the sprockets. A mismatched chain can jam on the sprocket and snap. As always, prompt cheerful refund if idea is bogus. Good luck, Dick B

 

[dutchman56]

I checked the sprockets for alignment and damaged teeth and found no problem. This is a brand new tractor and blower bought this spring and broke chain first time out after about 1 hour work. Next time broke chain after about 1 1/2 hour. Have new chain on now from TSC and go back up to camp on 26th. I know I will have to 4x4 in at least a km and get tractor out of garage and open up the road.

 

[ToadHill]

If its that new I'd have it back to the dealer for him to correct.