I have always been fascinated with elevators and have been doing research on hand powered elevators (and there smaller counterparts dumbwaiters). One thing I can't figure out is how the self retaining break system works. "The Sedgwick Automatic Brake Dumb Waiter Machines are a great improvement over all Automatic Lock and other Self-Retaining Machines, and are especially designed for pur- chasers who consider just as carefully what they are getting, as what they are paying. The Automatic Brake is independently sup- ported, thus relieving the machine of all end thrust, strain, and unnecessary wear." -Sedgwick catalog 1923 I would really like to see an animated cad drawing of such a mechanism working. I would also like to know the equation for figuring out the ratio I know if you have a rope wheel that is 20" in dimater attached to a pulley that is 10" you have a 1:2 ratio, same as if you had a gearing of one gear having 5 teeth and the other having 10. What I don't understand is how to factor them into one equation a 20" wheel going to a 5 tooth gear going to a 10 tooth gear going to a 5" pulley. Also if I wanted to build one of these things how many parts are still available and how many would have to be custom fabricated? I will leave you with a video of a hand elevator being operated https://www.youtube.com/watch?v=1JfRpbVLCLc note how the car stays stationeary when he stops pulling.