snapped chain.....twice

[Sumpter]

one other quick photo my favorite one the 40+ inch snowstorm that front blower didn't even slow down look at that pass by the car almost 3 foot deep you shouldn't be breaking chains or shear bolts perhaps there's something wrong inside that internal chain transmission? take care

WOW!! If it wasn't raining here now we would have at least that much new snow, but no luck. (Did I tell you I love the snow?) Since I have the blower in the shop I will give it the twice over and make sure everything is correct and tight. I hope I find a simple solution and have an ah hah moment to cure the problem.

 

[Don87]

View attachment 195586
Here is the infamous chain that is weaker than the bolts.
View attachment 195587
Here is the second stage shear bolt.
View attachment 195588
This is the back of the blower. If you look close you can see the black knob that you unscrew to access the auger shear bolt.
View attachment 195589
This is the auger shear bolt.

As you can see it is not a tube in a tube. It is two flanges bolted together. The do spin freely when the bolts are not in. Remember that I may have at most 25 hours on this blower. Only 70 hours on the tractor total. I also use the blade a lot like today. Rain sucks in winter.

Check the teeth on the sprockets, especially the one in the back that we can't see in the photos.

If a rock entered there, and broke a tooth off...............that could cause the chain to snap repeatedly.

Or if you are picking up gravel while blowing, that could snap a chain also, if it gets wedged between the sprocket and chain.

My old Cub Cadet, with the belt drive rear tiller.................I could till acres of ground without a problem..............until I picked up a rock, about the size of a 50 cent piece and about 1/4 to 1/2 inch thick. It would get caught between the idler pulley and the belt, cutting that 125 dollar belt in half every time.

My neighbors garden is about 15 ft by 25 feet..............I went thru 2 belts tilling his garden as a favor.

 

[Sumpter]

Everything is clear and there are no broken teeth. This has been an issue since I got the tractor and blower. I think I will put the new chain on and see if I have better luck.

 

[SPYDERLK]

View attachment 195586
Here is the infamous chain that is weaker than the bolts.
View attachment 195587
Here is the second stage shear bolt.
View attachment 195588
This is the back of the blower. If you look close you can see the black knob that you unscrew to access the auger shear bolt.
View attachment 195589
This is the auger shear bolt.

As you can see it is not a tube in a tube. It is two flanges bolted together. The do spin freely when the bolts are not in. Remember that I may have at most 25 hours on this blower. Only 70 hours on the tractor total. I also use the blade a lot like today. Rain sucks in winter.

That shear arrangement puts the shear point well outward of the shaft axis. This increases the leverage of the bolt -- essentially decreasing the shear force, increasing torque necessary from the sprocket. With this arrangement in particular your bolt should not be backed off but snugged to a couple ft-lb. Are you sure the mfg does not call for shearbolts that are grooved at the shearpoint?
larry

 

[Don87]

Everything is clear and there are no broken teeth. This has been an issue since I got the tractor and blower. I think I will put the new chain on and see if I have better luck.

Are you picking up gravel?

 

[Sumpter]

Yes I am picking up gravel or more accuratley rocks. I still feel that the bolts should shear before a chain break. I am in the mountains on old forest service roads and rocks 2-6" are common. I had hopeed that the snow had covered them all.

 

[Don87]

Yes I am picking up gravel or more accuratley rocks. I still feel that the bolts should shear before a chain break. I am in the mountains on old forest service roads and rocks 2-6" are common. I had hopeed that the snow had covered them all.

Negative, the bolts will shear when something gets into the augers(or fan) bad enough to stop them, but I think you are getting rocks into your chain, which is before the augers. Thus snapping the chain.

A 2 to 6 inch rock getting in between the chain and the sprocket is probably going to cause a problem.

(Blower picks it up with the snow......snow packs it into the the sides...........gets lodged between sprocket and gear...........snow keeps piling in pushing rock into sprocket.............)

I think we've found the problem.

What lead me to this conclusion was the amount of paint wear (and the pattern) on the blower, in such a short period of time.

 

[Sumpter]

The last rock was wedged between the ice chopper (?) and the housing. Not in the chain.

 

[RADIUM]

My farm road is 1500 foot gravel 2 inch flat gravel, I realize you're basically picking up stones why not hold the unit higher in the air or just adjust shoes to their maximum height might help a bit. I think you're going to have a real problem the beginning of each season until the stones are under a hard pack surfaces of ice and snow. I know that unit is quite expensive , but you might have to give up using it and just plow the roads rather than risk any more damage to the blower and possibly your tractor. Quite an expensive alternative trade it in for a unit with a shielded chain of course that would mean a three point rear snowblower which is a pain in the neck or modify the existing unit it could be done, or just keep extra chains and bolts laying around take care

 

[kevinj]

I spoke to both of my dealers this morning and they said Kubota does not give a spec for shear bolt torque.

They both did say that they should be snugged and then backed off so the bolt could be rotated but the parts did not rattle around.

They both said too tight and they will not shear reliably.

Hope this helps someone.