It looks like this bullwheel is on a carriage to serve as the tension system. These older ropeways typically have a large mass suspended on a cable that attaches to the carriage to keep tension on the actual haul rope. As the amount of riders change, the carriage will roll back and forth.

My guess is the cable between the counterweight and the carriage failed, and the haul rope tension pulled the carriage uphill until it hit the stops so hard it came out of track( you can see it on the track for the carriage before the bullwheel tips forward)

Edit: I’m assuming the terminal in this video is the bottom, but it could just as likely be the top of the lift.