This example shows a single-acting hydraulic cylinder controlled by an 3-way directional valve. It drives a load consisting of a mass, viscous friction, and preloaded spring. The pump unit is assumed to be powerful enough to maintain constant pressure at the valve inlet.
The valve is modeled by a 2-Position Valve Actuator block (Valve Actuator) and a 3-Way Directional Valve block (3-Way Valve). At the start of simulation, valve orifices A and T are connected and the cylinder chamber is connected to the tank. When the control signal for the valve exceeds 12, the valve spool moves, connecting valve ports P and A and closing the path between valve ports A and T. As a result, the cylinder chamber is connected to the pressure source and moves the load.