Small Engines (Lawn Mowers, etc.): Augar Pulley slipping, broken bolt, key way

Question
I have a Craftsman 9hp Snow thrower (model 536.887992). I thought the auger belt was slipping, but upon closer inspection I saw that the shaft was turning but the pulley was not. I tried tightening the two bolts on the pulley assembly which would work for a while but then would continue to slip. I continued to tighten the two bolts so much that the head broke off of one. I don't quite understand the design...why don't the bolts go into the shaft instead of just tightening against it? Am I missing something here? I have to try to remove the broken bolt to replace it but it seem that it will just happen again once replaced.

Answer

SNOW Mike
One of the problems that could be the source is the shaft is wore out and the bolts that tighten down the pulley are striped. There is also a key that gets put on the shaft and then it aligns with the pulley. You may have lost the key way thus causing the pulley to slip. I will send you a break down I suggest you get a new pulley and a key way. Remove the bolts if you can,you may to drill them out to get it off the shaft,just don't drill the shaft.Make sure you install the key and line it up with the spline on the shaft.