Activity theresa posted an update 3 weeks ago How Elevators Work – New Electronic Tubes Control Elevator Function 1940s http://www.luloot.com/elearning/how-elevators-work-new-electronic-tubes-control-elevator-function-1940s_c22c9b06a.html Elevators and their new electronic controls – 1940s. Invented by Elisha Otis…
How Elevators Work – New Electronic Tubes Control Elevator Function 1940sElevators and their new electronic controls – 1940s. Invented by Elisha Otis…