Model of Watt's Sun-&-Planet Gear

Wooden bench with central column with a balancing arm on top. One side of the arm is attached to a sun and planet gear which is a central gear with a second gear, the second gear is attached by a fixed metal rod to the end of the balancing arm, as the balancing arm moves up and down the second gear rotates around the first gear. At the other side of the balancing arm there is a hydraulic pump.