they detach and then roll on a series of rubber wheels that decelerate wheel by wheel on the way in and accelerate on the way out. the grip itself is spring lo

they detach and then roll on a series of rubber wheels that decelerate wheel by wheel on the way in and accelerate on the way out. the grip itself is spring loaded and the spring force is measured every time the grip passes through a terminal. if a grip is weak, the lift stops. if you look closely at a detachable grip, you'll see two wheels. those go into a funnel that squeeze open the spring loaded grip to release the haul rope. the chair or gondola cabin then is guided with one of those wheels while powered by the 20 or so small rubber wheels mentioned above that move the chair through the terminal. reattachment works the same, the wheels progressively speed up to the haul rope speed (5-6 m/s) as the funnel opens releasing the grip to snap back onto the haul rope. position sensors throughout the terminal and at the towers stop the lift if anything is out of position. (or a grip is weak, as mentioned above) and like any safety critical reliable system, a lot of hardworking humans check the system regularly.