The work presented in this book describes the specific steps undertaken to design and test two spool type control valves that will be part of Amsted Rail''s innovative vertical hydraulic damper system. The design challenge lies in the requirement that these spool valves must maintain a linear relation between pressure drop, flow rate, and position, during the extension and retraction cycles of the hydraulic damper. To this end, a series of laboratory experiments were conducted on spools having different land geometries in order to acquire the optimum apertures that will produce the desired performance based on simulation data provided by Amsted Rail. The effect of the working fluid temperature on the performance of the two designed spool valves was also investigated. Experimental testing was successful in identifying two spool valves that meet the provided design criteria within 2% for AW46 hydraulic oil working fluid at a temperature of 25°C (77°F).