OWB=One Way Bearing.
It's a type of bearing that will only roll in one direction. If you move it in the opposite direction, it locks. They are used in pull starters and roto-starters on our engines.
One Way Bearing. There is one that's used to start your engine and there's another in your trans that allows a two speed. It rolls freely in one direction and clamps down on the shaft in the other direction.