Hello Physics Forum, I am a second year student and with a team of 4 and instructed to design an auto belay for rock climbing. The main functions it has are: descending, braking and switching from a stopped position to descending. We've come up with a few designs/concepts for descending, braking, switching but kind of stuck on how to pull the rope up after climb. Do you guys have any ideas? If so, try to be specific. Thanks! Additionally, if you guys have any ideas for any other functions, feel free to share. Note: We only have one concept for ascending the rope and it is using a constant tension spring. Similar to a tape measure.