Converts mechanical from an electro-mechanical into hydraulic signals. This is mainly achieved by throttling an oil flow with controllable mechanical resistors or transforming the kinetic energy of an oil flow into hydrostatic energy. They also acts as hydraulic amplifiers at the same time. The three main designs are as follows (Figure M 5):
- the spool (pilot) control valve, (a),
- the flapper-nozzle system (b),
- the jet pipe (c).
Figure M 5: Hydro-mechanical signal converter