[fruch]

My model 47 snowblower broke down yesterday. The large drive gear on the back came loose and slipped off the shaft. I lost the shaft key so I ordered a new one and should have it in a few days.
I inspected the gears and the chain, they appear to be in good shape. When I put the large gear back in place, do I push it back on the shaft (towards the back of the housing) until it stops or should it sit a little away from where it stops when I push it on. Also, when I tighten the set screws on the gear hub, is there a torque specification I should tighten them to? Thanks for any advice.

 

[rwmeyer]

Let me start by saying I'm not all all familiar with a 47. BUT, your basic question will determine the alignment of the 2 sprockets...whether they're on a snowblower or a conveyor belt, no difference!

You should have one sprocket/gear still attached to your snowblower. Start your gear on the shaft and place a straight edge on the side of the gear. Push the gear on so that the straight edge just touches the other gear (still mounted on blower). As far as a "spec", tighten set screw...when you see the allen key bend 1/4 to 1/2 inch, that's tight!

All that said, I'm thinking you may have some kind of distortion/bend between your drive and driven sprockets and that's why the gear came of in the first place. If your 2 shafts...drive and driven/auger are parallel, the chain should have kept the gear on the shaft. See if you have any movement left to right on the drive gear (I'm assuming this is the gear still on the blower). Check your auger for any movement left to right (I'm assuming this is where the large gear goes). If little (less than 1/32") or no movement, check if drive gear is out of alignment with auger: Place a straight edge along the side of the drive gear. It should line up where the large gear goes. Turn drive gear 1/2 turn and repeat check. I'm not familiar enough with the 47 to properly explain this last check, but you also need to check if your entire auger housing is not "twisted" to your drive gear. Possibly (???) a straight edge on your large gear and them measure at the large gear end to sheet metal guard (??) and then to the same sheet metal guard on the drive end.

Hope I didn't confuse you, Bob

 

[12ultra]

now this is scary!! I just had my big gear on my 54 blower lose its square key yesterday ace hardware had the key and upon inspection my chain was stretched to beat **** so I got a new chain from ace also its #40 chain like said before just alien the chain and snug it up and your back in business... oh and put some grease on it !!

 

[fruch]

Thanks for the help Bob, The straight edge suggestion sounds useful, I will give it a shot. The set screws are fairly large bolts, one tightens down on the shaft, one tightens down onto the shaft key. I'll tighten them up as best I can. Other than that the repair looks to reasonably easy, I just have to wait for the replacement shaft key to be delivered.

 

[jgayman]

now this is scary!! I just had my big gear on my 54 blower lose its square key yesterday ace hardware had the key and upon inspection my chain was stretched to beat **** so I got a new chain from ace also its #40 chain like said before just alien the chain and snug it up and your back in business... oh and put some grease on it !!

Your chain will last a lot longer if you use a good chain lube instead of grease. You need something that penetrates into the rollers and pins. Grease, while it gives the appearance of a lubed chain, in reality the grease just hangs on the outside of the chain and does not penetrate into the rollers and pins. Bel-Ray makes a good chain lube product. Best results are usually achieved by using something designed for dirt bikes. It will typically penetrate the rollers and not fling off under use.

 

[fruch]

I am trying to understand what would loosen up the large gear enough to make it slip off the shaft. Everything looks OK. The snow was a little icy and the blower clogged up a little bit, but if that was the real issue a shear bolt would have broken.

 

[jgayman]

I am trying to understand what would loosen up the large gear enough to make it slip off the shaft. Everything looks OK. The snow was a little icy and the blower clogged up a little bit, but if that was the real issue a shear bolt would have broken.

It just happens. Usually from vibration. Someone probably forgot the Loktite when it was assembled.