Elements of a Hydraulic System

The main elements of a hydraulic system are

The Reservoir
The Reservoir contains the hydraulic liquid.  The hydraulic liquid is drawn by the pump into the hydraulic circuit.  The liquid is again returned to the reservoir.

The Pump is the centre of any hydraulic system.  The pump pressurizes the hydraulic liquid to the rated pressure and makes it available for the other components.  The pump is driven by a prime mover such as an engine or a motor.

Motor or actuator
The motor or actuator converts the hydraulic energy into mechanical energy.  The motion can be either linear or rotary.

For linear motion, a piston and cylinder are used.  For rotary motion, a turbine is used.  The is called a hydraulic motor.

Pipelines and Valves
The hydraulic system contains numerous valves and pipelines.  The liquid passes through the pipelines.  The flow and direction are controlled by the valves.