The two-stage on/off valve scheme is studied in this thesis which is able to rapidly actuate within the fraction of a second for directional flow control applications. And also, it was able to replicate characteristics of direct operated solenoid on/off valves in the same category, with the addition of higher flow rate capacity up to 200 l/min and above with pressure drop under 5 bar. The valves utilized for piloting of the hydraulic operated cartridge valve are the normally closed and normally open direct solenoid operated on/off valve. In the experiments, the internal piloting structure is adopted to avoid external pressure source and keeping valve operation dependencies minimum to the electric power. The switching time was found to be lowest at 100 bar, that is approximately 12 ms for opening and 30 ms for closing from the point of activation signal. It is also observed that the flow rate has negligible effect on the switching duration and changing the poppet area ratio to 50% of Ax from 96% can reduce down the closing time. Further, it was observed that the internal piloting has its drawbacks which creates a closed loop between main valve metering edge and pilot chamber. This resulted in oscillations in form of poppet movement near the dead end on either side of the stroke, and also if the system is not stiff or due to pressure waves traversing in the long hoses. Another positive outcome from the measurements showed that different switching methods such as, intermittent, continuous and pulse switching can be performed in a controlled manner, but the study was limited to the capability of the valve scheme. Moreover, the simulation model is also built in the Matlab/Simscape environment to refine the valve model based on the experiment results for further measurements that were limited by the physical system. Additional simulations are conducted to reduce the marginal difference between the opening and closing duration by restricting the stroke length to 5 mm, contrary to the original 8.5 mm, at 200 l/min and the switching duration was considerably reduced by half of the original duration. The experiments were conducted for flow in one direction only, whereas in simulation also the bi-direction flow capability is also carried out to displace an actuator with constant velocity, while lifting and lowering and holding of the load to certain position
