This example shows an actuator built around a telescopic hydraulic cylinder, which is equipped with three rods interacting with each other through hard stops. The effective areas of the rods are set to 20, 16, and 12 cm^2 respectively, which causes the first rod to move first, followed by the second, and then by the third rod. The actuator is controlled by a 2-position 3-way valve, which connects the actuator chamber to the tank at neutral position. As the control signal is applied to the valve, the actuator chamber is connected to the pump and the actuator starts extending. The rods are retracted by external load when the chamber is connected to the tank. The power unit relief valve is set to 50 bar, and maximum load to be handled by the actuator is 2500 N.
The plots below show the pressures in the cylinder and the extensions of each stage.