snapped chain.....twice

[Sumpter]

I will be going by the NH dealer on Thursday so will stop and see what they have to say about it. The one shear bolt is about six inches from the gear box, then the shaft goes to the chain, then chain to the auger sprocket. Seems like there could have been a shear on the auger itself but there isn't. The second is on the 2nd stage.

 

[Sumpter]

Okay I am about to give up. Snapped the chain twice again. Once yesterday and again today. I have the 60H on already and the bolts just won't shear for some reason. It has the right bolts. I now have 5 master links in the chain. I did get a new chain so might change it out. Just don't understand this problem.

 

[flyingcow]

It just seems to me that it's a problem the dealer either needs to fix, or more likely, needs to replace the whole unit? they'll need to try it out. Ask for a "loaner"?

My blowers(rear mount) have had a shear bolt on the PTO and a second on the shaft, just before sprocket that drives the augers. only time i shear a pin, is when i engage the pto while anything above a low idle.

 

[crazyal]

I think you should go to the dealer as well. If you aren't ready to I would remove the auger shear bolt and try to blow snow without it. I've never tried it but on my blower I don't even think the auger would turn even without snow.

Maybe the sprockets aren't inline and you're not breaking the chain from force but are twisting it loosening up the plates and weakening the chain?

 

[Jackfr]

I was breaking chains on our 8' blower. I replaced the chain and got some grade 2 bolts from True Value to replace the shear bolts (one 1/4" bolt on the sprocket and two 5/16" bolts on the drive shaft). The bolts shear way before any damage to the chain or sprocket. If you don't over work the blower they last quite awhile but I carry extras in the tractor with wrenches with me. It's a lot quicker and cheaper to replace these cheap bolts than other parts of the blower.

 

[wedge40]

Have you removed the shear bolts? How tight are the nuts? I would look at getting a replacement chain.

Wedge

 

[etcallhome]

After talking to dealer about this problem ,If they don't talk to manufacture about this problem , I would call and find out if they have had any problems.
Could just be the chain ,, I read where you had a new one just not put on .
Grade 5 all thread will break a lot quicker than the others.. Last winter I went through 15-20 all threaded.. changed to just threaded on end of bolt maybe 4 rest of winter and this year total..
Good Luck

 

[kevinj]

I would like to see some pics of the drive line, shear points etc.

Also where is the rock wedging?? In the augers or impeller.

Some shear bolts MUST be left slightly loose to work properly.

On my Kubota (Rad) the impeller bolt cannot be tight or the two flanges clamped together add to the shear. If slightly loos the bolt is the only shear point.

 

[Jay4200]

Okay I am about to give up. Snapped the chain twice again. Once yesterday and again today. I have the 60H on already and the bolts just won't shear for some reason. It has the right bolts. I now have 5 master links in the chain. I did get a new chain so might change it out. Just don't understand this problem.

You either have a defective chain, your tensioner is improperly adjusted, or something is misaligned in the chain drive. The chain should be snugged up with the tensioner - if you leave slack in the chain, it will cause it to prematurely snap. If your chain is snug when adjusted, I would take it back to the dealer for a chain drive inspection and at the very least demand a new chain.

My 6' blower has two shear bolts - one standard 5/16" snowblower shear bolt on the PTO shaft, and one 1/4" grade 5 bolt on the shaft between the transmission and first chain drive gear. I got the blower packed full of cement-like snow two weeks ago - I tried turning the blower over (at idle) before it was fully cleared and immediately broke the PTO shear bolt.

My blower is a 25-40HP rated blower, but snapping at idle tells me that the shear bolts will break with WAY less than the 37HP that my tractor PTO can produce. A healthy #60 drive chain can certainly handle 40HP (I run similar HP through smaller chains on my dirtbikes all the time).

JayC

 

[flyingcow]

I would like to see some pics of the drive line, shear points etc.

Also where is the rock wedging?? In the augers or impeller.

Some shear bolts MUST be left slightly loose to work properly.

On my Kubota (Rad) the impeller bolt cannot be tight or the two flanges clamped together add to the shear. If slightly loos the bolt is the only shear point.

Don't know much, but i've never left a shear bolt"loose" to work properly. You will oblong the holes the bolts are in. Makes no sense to me. But, what do i know? been snowblowing for 15yrs.

Explain "loose"

 

[kevinj]

Don't know much, but i've never left a shear bolt"loose" to work properly. You will oblong the holes the bolts are in. Makes no sense to me. But, what do i know? been snowblowing for 15yrs.

Explain "loose"

Most shear bolts go thru a yoke and shaft arrangement so the bolt is not compressing the outer piece to the inner piece.

On my blower there are 2 flanges at 90° to the shaft and a bolt goes thru them. The tighter the bolt is the more force to shear. The impeller moves just a bit as the bolt is backed off a tiny amount after tightening.

Both of mine came loose from the factory. They probably would not bother with self locking nuts if they were supposed to be tight.

The auger drive on one of mine has a shaft within a tube and a thru bolt, that on has a lock washer and is put in tight but the auger is still not tight on the shaft.

Oh, and you have me beat by about 5 years running a blower but I have about 35 running machinery, by no means am I an expert.

One last thing, the owners book does not give a torque spec, they say "check for proper tightness", a lot of good that is.

 

[Sumpter]

I will get some pictures tomorrow showing the bolts and chain. I realized I don't have a big enough chain breaker to get the new chain to the right length. I will have to grind it I guess. I feel the alignment is good. I put a straight edge on it and all was good. I am thinking the chain may be a bad one and the bolts are tight but not super tight. They have nylon lock nuts so that is not an issue.
The last two were rocks in the auger, but it still should break the bolt instead of the chain.
Need to call the dealer I guess.

 

[flyingcow]

Most shear bolts go thru a yoke and shaft arrangement so the bolt is not compressing the outer piece to the inner piece.

On my blower there are 2 flanges at 90ｰ to the shaft and a bolt goes thru them. The tighter the bolt is the more force to shear. The impeller moves just a bit as the bolt is backed off a tiny amount after tightening.

Both of mine came loose from the factory. They probably would not bother with self locking nuts if they were supposed to be tight.

The auger drive on one of mine has a shaft within a tube and a thru bolt, that on has a lock washer and is put in tight but the auger is still not tight on the shaft.

Oh, and you have me beat by about 5 years running a blower but I have about 35 running machinery, by no means am I an expert.

One last thing, the owners book does not give a torque spec, they say "check for proper tightness", a lot of good that is.

this is how we(mainly me!) learn when we're wrong, or at least not educated/uptodate on "stuff". What you have for shear bolts is lot different than what I've seen. Yes, I've been snowblowing for 15yrs, but I've always run rear mounted(mainly Lucknow) snowblowers. Big azzed beast of blowers. I had one that was 9ftx4ft. Buckle up and ride........fun clearing snow. I once chewed up a 2x4 in that ole' beast. My shear pins aren't yours.

And always remember........experts built the Titanic!!!

 

[kevinj]

And always remember........experts built the Titanic!!!

Were they experts or engineers:confused2:

By the way, the shear bolt design on my blower is war easier to replace than the the tube in tube type since the shafts hold the alignment and you can clearly see where to line it back up.

 

[kevinj]

and the bolts are tight but not super tight. They have nylon lock nuts so that is not an issue.
The last two were rocks in the auger, but it still should break the bolt instead of the chain.
Need to call the dealer I guess.

Does your shear points look like mine???? Or do you have a tube within a tube???

Have you pulled the shear bolts and make sure the items can rotate freely when the bolts are out????

 

[Don87]

With the shear bolts removed, do the parts spin freely? That means..........spinning seperately from each other as they should?

On the old Cub Cadet I owned, the brand new tiller stopped working with the first rock that the tines hit.

Turned out that the parts were "painted together" at the factory.......thereby snapping the chain.

 

[kevinj]

With the shear bolts removed, do the parts spin freely? That means..........spinning seperately from each other as they should?

On the old Cub Cadet I owned, the brand new tiller stopped working with the first rock that the tines hit.

Turned out that the parts were "painted together" at the factory.......thereby snapping the chain.

Pulling the pins and checking for free movement should be part of everyone's annual PM.

It is sad that the owner manuals are so lacking in detail about the the shear pins and slip clutches.:confused2:

They seem to assume that everyone knows this stuff.

On a snowblower where you pick up salt and do not shear a pin for a while the parts can rust together and of course will not shear when needed.

 

[Don87]

Pulling the pins and checking for free movement should be part of everyone's annual PM.

It is sad that the owner manuals are so lacking in detail about the the shear pins and slip clutches.:confused2:

They seem to assume that everyone knows this stuff.

On a snowblower where you pick up salt and do not shear a pin for a while the parts can rust together and of course will not shear when needed.

Exactly :thumbsup:

On the old Cub that I talked about earlier, the tiller had an 'internal slip clutch' that was painted together.

 

[RADIUM]

Wow I just came across this, I had the same setup on my TC 40 DA and never once in two years broken chain moving heavy snows as a matter of fact never broke even a bolt? That includes the Valentine's Day storm February 06 with a total of 43 inches in one shot what a storm that was the first time I was concerned about living so far out in the country, state plows didn't make the roads for two days, What kind of lubrication are you using on that chain? Perhaps it's just a bad batch of chains. if you've correctly adjusted the tension and the gears look okay can't think of anything else? it was honestly bulletproof for me it will be interesting to hear the outcome take care

 

[crazyal]

Most shear bolts go thru a yoke and shaft arrangement so the bolt is not compressing the outer piece to the inner piece.

On my blower there are 2 flanges at 90ｰ to the shaft and a bolt goes thru them. The tighter the bolt is the more force to shear. The impeller moves just a bit as the bolt is backed off a tiny amount after tightening.

Both of mine came loose from the factory. They probably would not bother with self locking nuts if they were supposed to be tight.

The auger drive on one of mine has a shaft within a tube and a thru bolt, that on has a lock washer and is put in tight but the auger is still not tight on the shaft.

Oh, and you have me beat by about 5 years running a blower but I have about 35 running machinery, by no means am I an expert.

One last thing, the owners book does not give a torque spec, they say "check for proper tightness", a lot of good that is.

That's how both my auger and impeller are set up and I tighten them down, they came tight from the factory. I figure I don't want them loose. If the plates are loose they'll move just a little during normal operation and will cause wear and the hole for the shear bolt to oblong. I've sheared one auger bolt but about 4 impeller bolts so far this season so I would say extra friction of the plates isn't a problem.