# Relative speeds of auger and impeller



## Dave C (Jan 26, 2015)

My brother's old Craftsman 5.5/24 stopped throwing snow this morning. He says when he engages the auger the auger blades turn but the impellers only turn slowly. I dunno what the relative speeds of the 2 stages are, so I can't say if something's broken or what. Where would you guys look?

TIA


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## Geno (Nov 29, 2011)

when you say 'auger' are you referring to the big one(s) in front (most refer them to auger)? if so, if they are spinning good but the impeller in back is slower then it kind of don't make sense- the impeller shaft has to be spinning to make the auger (actually Rakes) turn in front. Only thing I can think of is he has it worded wrong or.. the roll pins sheared holding the impeller on the shaft (very unlikely)? If he means impeller is spinning good in back but auger in front slowed down.. then it's gear box stripped gear and is skipping or shear bolts broke in auger shafts. Check them first. they will sometimes still turn slow sheared off until under heavy load.


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## Ken05 (Feb 13, 2015)

That sounds like a drive belt issue, pull the cover and see whats happening.


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## Town (Jan 31, 2015)

Dave C said:


> My brother's old Craftsman 5.5/24 stopped throwing snow this morning. He says when he engages the auger the auger blades turn but the impellers only turn slowly. I dunno what the relative speeds of the 2 stages are, so I can't say if something's broken or what. Where would you guys look?
> 
> TIA


The impeller is located at the back of the auger opening and spins at about a 1,000 rpm. The auger is located at the front of the auger opening and turns at less than 100 rpm. So a huge difference in speed. The engine drive pulley drives the auger drive belt to turn the fairly large diameter pulley attached to the impeller shaft. The shaft drives the impeller through roll pins or bolts passing through the impeller hub and through the shaft and through the other side of the hub. The impeller shaft has a gear that engages the auger shaft gear to drive the two augers through shear bolts. 

So with the motor off the auger and impeller should not turn easily, especially if the brake on the bottom of the auger pulley is working properly. If the auger shear bolts are broken then auger may turn due to friction but will not move snow toward the impeller so no snow will be thrown.

Usually a worn out auger belt will turn the impeller and auger but will stop when driven into snow due to the loading exceeding what the belt can transfer to the pulley.

Good luck.


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## Shryp (Jan 1, 2011)

Yea, mostly a 10:1 ratio. The impeller turns at 1000 - 1300 rpm and the augers turn at 100 - 130 rpm.


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## ELaw (Feb 4, 2015)

As others have said, the first thing to check here is terminology! The "auger" is in the very front of the snowblower and is helical (some people say "augers" since technically the left and right are separate pieces), the "impeller" lives behind the auger, under the chute. The impeller turns considerably faster than the auger... when everything's working properly.

As others have also said, having the auger fail to rotate is much more common than an impeller problem. No auger rotation can mean broken shear pins (aka shear bolts) or a gearbox problem.

If the auger is in fact turning but the impeller is not, it would mean that the pin(s) that hold the impeller onto its shaft are broken. That's much less common but it *does* happen - I experienced it just a few weeks ago.

If both the auger and impeller aren't turning (or are turning unusually slowly), the problem is probably related to the belt that drives them.


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## Dave C (Jan 26, 2015)

Thanks, guys. I had a look-see this afternoon and it appears that the roll pins attaching the impeller to the shaft have sheared. I'll start a new thread in the Craftsman sub forum about what is needed to service that problem.

Thanks again.


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