Of the most important forms of energy that can be used for drives (mechanical, hydraulic and pneumatic) only mechanical energy does not require conversion (Figure E 29).
For all forms of energy the detour via an energy conversion must be selected that on electrical systems signifies rectification or frequency conversion, while on fluid-based systems a pump or a compressor is required. The drive element in electrical systems is the electric motor, and in fluid technology the cylinder or the motor (Figure E 30).
These systems are therefore more complex and have worse efficiency than the mechanical drive. However, the control and regulation behaviour are significantly better.
Figure E 29: Block diagram of a mechanical drive
Figure E 30: Block diagram of a drive with energy conversion