In the event the force drops, springs result in the clutch to release. Evenly spaced ridges, referred to as splines, line The within and outside with the clutch to lock to the gears as well as the clutch housing. You may read more about these clutches in How Automatic Transmissions https://clutch-plate89876.blogdeazar.com/33181135/the-smart-trick-of-clutch-plate-that-nobody-is-discussing