Hydraulics are sometimes looked at as an alternative to electric motors. Hydraulic systems use an incompressible liquid (as opposed to pneumatics that use a compressible gas) to transfer force from one place to another. Since the hydraulic system will be a closed system (ignore relief valves for now) when you apply a force to one end of the system that force is transferred to another part of that system. By manipulating the volume of fluid in different parts of the system you can change the forces in different parts of the system (Remember Pascal's Law from high school??). So here are some of the basic components used (or needed) to develop a hydraulic system.