Servomotor

In the early 1880s, as battleships increased in size, the movement of the rudder had to be power-assisted to facilitate the task of the helmsman and enable the vessel to change course rapidly. In order to do this using the steam produced by the ship’s engine, the system had to be servo-controlled so that the rudder’s angle corresponded to the helmsman’s command. Joseph Farcot’s servomoter is a servo-control device using the retroaction principle: it controls the flux of steam acting on the rudder by adapting it to the rudder’s position. Until the rudder has reaches the desired angle, the steam continues to arrive in the cylinder and ‘push’ the rudder. When the rudder approaches the desired position the control rods automatically shut off the steam supply without the helmsman having to use the control lever. Farcot donated this model to the Conservatoire after the Universal Exposition in 1889.