I had a jam in my chipper that got the belt smoking (and flaming) and when I took the shroud off to look at the belt & pully, I found this special little deal on the engine shaft:




I have never seen this sort of thing done by design, I'm expecting that when the engine was assembled the assembler didn't have the parts he should have had so made do with this deal. I also expect that somewhere in the engine, there's a washer with a square cut-out in it.

All in all, I plan to cut out the plate for the key and then bolt it in correctly, unless somebody tells me that this is really supposed to be this way but I really don't think so, just sharing the silliness.

 

You should see if the key can be pushed farther in if not you should cut the key off flush with the pulley so that the washer can hold the pulley and the key on. If you cut a hole in the washer the key could come out.

 

I'd say your bolt is loose, there probably is a set screw in the pulley that is loose, and the key has walked out. There will be no washer in the engine anywhere with a square cut out.

This won't cause your belt burning problem though.

 

Remove the bolt and washer, tap the key back in flush with the pulley, reinstall the washer and bolt but put some blue LocTite on the screw threads this time.