Kubota B2782 snowblower destroys its chain after every use! Help!

[87mark7lsc]

The chain does get tight but it's not from our misadjusting it. At some points it has a ton of slack and as you turn the impeller sprocket at one point it tightens and binds. We set tension at that spot and make sure the chain has slack and everything turns freely. In the picture the shaft runout was about .07 inch and the hub of that big sprocket was showing .15 inch runout. We noticed today that the keyway in the impeller has play, just like the gear reduction shaft did. We ordered a new shaft, it's the only thing left. I bent one a few years ago right behind the gearbox, this is the second one. We're on our third big sprocket

 

[ericher69]

The chain does get tight but it's not from our misadjusting it. At some points it has a ton of slack and as you turn the impeller sprocket at one point it tightens and binds. We set tension at that spot and make sure the chain has slack and everything turns freely. In the picture the shaft runout was about .07 inch and the hub of that big sprocket was showing .15 inch runout. We noticed today that the keyway in the impeller has play, just like the gear reduction shaft did. We ordered a new shaft, it's the only thing left. I bent one a few years ago right behind the gearbox, this is the second one. We're on our third big sprocket

wow I don't know what you are doing with that blower but I do up to 50 residential drives per snowfall and have had a few minor issues! Super reliable unit.

I cannot believe that you need to change all these parts.

Sent from my iPhone 5s 64Gb using TractorByNet

 

[CDN Farm Boy]

Something just doesn't seem right to me that you are going thru that many parts. Runout in the sprocket is most certainly from a bent shaft but the bigger question is why is the shaft bending in the first place? Bending the same shaft twice is even more alarming.

What tractor are you running this blower on? And how many hrs approx is on it?

 

[87mark7lsc]

The blower is on a 2008 Kubota B7800. Tractor has 3000 hours, blower has almost 800 now it's been a busy week! I'm not sure how I bent the first shaft, must have picked up a frozen chunk of snow or something. The tractor is used on sidewalks.

We took the newest sprocket to a machine shop today and it was spun on a lathe and the bore was slightly off. That's the second sprocket we've bought that's been like that. We have a used one that we put back on today. Runout was less at .05 inch measured on hub of sprocket and the chain isn't binding now. The tension changes slightly as we turn by hand but it's much better than before. This pulley has an extra set screw on the bottom that the two mis bored ones didn't have

 

[BAP]

Does your shearbolt break like it is supposed to if you hit something hard? Is it the correct grade?

 

[87mark7lsc]

Yeah I usually nick a few curbs and break some shear bolts every year. A few fan shear bolts as well. Our dealer is going to warranty our sprocket and order us a new one. We may take it to the machine shop before we install it to check the bore center again

 

[Winmac]

It's difficult to measure runout with weld on sprocket hub assembly's, none of the hub surfaces are really true to the bore. And they are only as true as the machinist took the time to dial the hub in before machining.

 

[87mark7lsc]

Update: after running over 4 hours with this sprocket Friday, the chain was in good physical condition and still had oil on it when we pulled the cover to inspect. I find this very interesting, I'm assuming that these results show that the higher runout with our previous setups was what caused our issues

 

[Jay4200]

I thought there might be a bent shaft in the picture somewhere. Also, use aerosol motorcycle chain lube instead of oil. I use this:

Dirt Bike Maxima Chain Guard Chain Lube | MotoSport

 

[Sodo]

I'm assuming that these results show that the higher runout with our previous setups was what caused our issues

I think runout is the culprit only if the runout caused the chain to be over-tight at times.