Selected symbols for fluid power systems
BS 2917 NF E 04-056
Directional control valves, control methods
3/2-way valve | ![]() |
at basic setting the supply port is
closed, e. g. single-acting cylinder exhausts at basic setting the supply port is open, e. g. single-acting cylinder ventilates |
4/2-way valve | ![]() |
with two flow positions and shared exhaust, e. g. for double-acting cylinder |
5/2-way valve | with two flow postitions and separate exhausts, e. g. for double-acting cylinder | |
4/3-way valve | with floating neutral position and two positions of flow | |
5/3-way valve neutral position closed
neutral position opened
neutral position ventilated |
with three switching positions, neutral position in the middle .The flow positions marked with double arrows mean that these valves are reversible, i.e. the flow can go in both directions. |
Control methods: Mechanical , Muscular, Pneumatic, Electrical
Mechanical control |
Manual operation |
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by plunger or push-button by spring by roller by roller, only working in one direction (idle return) |
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general (not indicating actuation type) by push button by lever by pedal |
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Pneumatic actuation |
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directly working due to pneumatic actuation
indirect actuation pilot actuated due to pressure relief of pilot valve |
directly working due to pressure relief
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Electrical actuation |
Combined actuation |
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by electro-magnet with a winding | ![]() |
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by electro-magnet and pilot valve |