hydraulics: directional control valve (connection diagram and drawing) the two valves are connected in a way they can move together combining the two pistons how graphical symbols of directional control valves come about three different shift positions can be set description ordernumber 224 see also: hardness test hydraulics: connection diagram of a feed control pneumatics: 3/2-, 4/2- and 5/2-port directional control valves slotting machine