This is a "planetary set" out of the axle. One of the little gears broke, or the bearing it runs on came apart, then it chewed up the gear. I'm not sure. When the little gear broke it made a very sudden stop. Locked the left rear wheel. I'm glad I wasn't going down the road when it let go. Now I am waiting for some new parts. Should have it back together Friday afternoon or Saturday. I'll clean everything up good and slap it all back together so I will be ready to find the next breakdown.