Which of the following is NOT a component of hydraulic systems?

In hydraulic systems, the primary components include actuators, reservoirs, and valves, which work together to control the flow and pressure of hydraulic fluid. Actuators convert hydraulic energy into mechanical energy to perform work, reservoirs store the hydraulic fluid, and valves regulate the flow and direction of the fluid within the system.

A compressor, on the other hand, is typically associated with pneumatic systems rather than hydraulic systems. It is used to increase the pressure of gases and is not involved in the hydraulic process where liquid fluids are utilized for power transmission. Therefore, identifying the compressor as not being a component within hydraulic systems is accurate, as it does not serve any function in the operation of hydraulic circuits.