This example shows an amplifier that consists of two fixed orifices, two variable orifices that represent nozzles, flapper, and main valve simulated with mass, viscous friction, and centering spring. Two translational converters represent servo-actuators on both sides of the main valve. The feedback spring SPR_FBK connects the flapper and the main valve.
The amplifier is actuated with a force source, which represents the force generated by an electromagnet. The flapper displacement causes pressure difference between converter chambers, which results in the main valve displacement. The main valve, through the feedback spring, acts on the flapper in the opposite direction. The amplifier comes to a steady-state position as the force equilibrium on the flapper is reached.