The pump in this model acts in a fixed displacement mode that produces a given flow rate regardless of its output pressure. When the control valve is closed (zero area) then the pump produces an output pressure that is purely a function of the leakage orifice to the tank with coefficient C2. The pump will produce a steady state pressure of Qmax/C2 as long as it continues to flow at the maximum rate.
When the control valve opens the pump pressure produces a flow into the cylinder. The piston will then move and compress the spring until it produces a counter-acting force and pressure = force * piston area. The steady-state pressure inside the cylinder will be equal to the pump steady state pressure once the piston movement stops. The only way to make the piston move in the opposite direction is to reduce the flow rate out of the pump.
The control valve orifice area (A) only changes the velocity of the piston position and not its steady state position.
