A member here had a major bearing failure for the chain drive tensioner on his snow thrower. Both needle bearings in the ears completely gave up, the sprocket shifted over into the casting and then the chained jumped off the sprocket. Sometime during the event, the spirol pin sheared.
The reason was lack of grease. The member can NOT be blamed as whoever put needle bearings in used ones that had no provision for grease to actually reach the needle bearings. The grease fittings just smeared grease around the outside of the bearing.
We both looked for a replacement casting but they are next to impossible to find.
I got the piece and used my three ton press to get it apart. ( just barely, I thought I would have to do it at work ).
The picture shows the original sprocket that got against the outer bearing cage and as the steel sprocket wore, it "ate" the casting away. As seen in the replacement sprocket ( it's a plus 1 tooth) , it should be flat.
Since I could get measurements off the sprocket, I made a "mirror image" of a bronze washer to replace the aluminum that was worn away.
I was able to save the transfer shaft. New needle bearings and a new sprocket and now it's ready for next winter.
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I'm having problems attaching pictures. I will email the pics to Roland and he'll add them at his convenience.