Servos vs Pneumatic Systems. As I was poring over my links to pneumatic systems for Halloween projects, I noticed all my links to servos as well. It is easy to get confused about which system to use and why. Either servos or pneumatics can be used for interesting animation effects. At Delta Computer Systems there is a good comparison of fluid power versus electromechanical power systems [PDF] — some of the advantages of hydraulic are explained here, including better performance for limited duty cycle applications which will certainly be true of my props. Electromate has a short comparison of the different kinds of motion systems.