Device used to control or the output of the fluid by influencing the start, stop and direction, as well as the pressure and/or flow rate of the pressure fluid acting in the system (Figure V 3).
Valves are differentiated according to:
- task: directional, pressure, flow and check valves (Figure V 4),
- design: seated valves (conical, ball and disc seated valves), (lengthwise) and rotary valves (Figure V 5),
- working method: specified switching positions (2-position directional valves, check valves, 3-position and multiple position directional valve), adjustable working position (throttle, flow control valves, pressure valves) and continuously adjustable working position (manually operated directional valves), continuously adjustable valves),
- controlled ports: 2-way, 3-way, 4-way valves and more;
- actuation (types): manual, mechanical, pressure (hydraulic, pneumatic), electrical actuation.
![644efd099fc960c97df69681819d11b7e6f09044 0001_ventil.gif](/fileadmin/smc/files/644efd099fc960c97df69681819d11b7e6f09044.gif)
Figure V 3: Control with the most important valves
![d1250a90d13de9d06b977165a21a0a0fb9da9875 0002_ventil.gif](/fileadmin/smc/files/d1250a90d13de9d06b977165a21a0a0fb9da9875.gif)
Figure V 4: Tasks of the valve functions
![e41705db342d5882fe80277f00b1a000c86a202a 0003_ventil.gif](/fileadmin/smc/files/e41705db342d5882fe80277f00b1a000c86a202a.gif)
Figure V 5: Principles of valve mounting