The elementary school I went to for K-4th grade had dumbwaters very similar to this one. Relatively same size, looked to be similar vintage, except I believe they were Sedgewick dumbwaters. They had buzzers rather than the "in use" lights, and used the same type of key. Unfortunately, I never got to see them in action up close, but man, would I have killed to see inside their shaftways! Does this one have a counter-weight? It's a bit hard to see in there... The only things that'd make this video better is if we got to see the motor up close, and/or got a look at the buffers at the bottom of the shaft... The school I went to for 5th was entirely ground level, so it had no elevators of any kind.
