Symbols

1. Hydraulic Symbols

2. Piping and Tubing Symbols
Normal working line
Flexible working line
Pilot line
Drain line
Enclosure outline
Direction of flow

3. Crossing lines
Joining lines

4. Reservoirs
Reservoir
Connecting lines above fluid level
Connecting lines below fluid level
Sealed
Open

5. Basic filter/strainer
Separator
Filter-separator
Manual Automatic
Fluid conditioning
symbols are a
diamond shape

6. Cooler
Liquid Gaseous
Heater
Temperature controlled

7. Pressure
Temperature
Flow meter, rate
Flow meter, totalizing
Float switch
Nozzle
Pressure Switch

8. Pumps
Fixed displacement
Unidirectional Bidirectional
Variable displacement,
non-compensated,
unidirectional
Variable displacement,
non-compensated,
bidirectional

9. Pumps
Variable displacement,
pressure-compensated,
unidirectional
Variable displacement,
pressure-compensated,
bidirectional
M Electric Motor Internal combustion

10. Motors
Fixed displacement,
unidirectional
Fixed displacement,
bidirectional
Variable displacement,
unidirectional
Variable displacement,
bidirectional

11. Valves
Normally closed, two-way,
two port
Normally closed, two-way,
two position, two port
Normally closed, four way, three
position, four port

12. Valves
Normally open, two-way,
two position, two port
Normally open, two-way,
three position, three port
Normally open, four way, three
position, four port
Normally open, four way, infinite
position, four port

13. Relief Valve
Represents the pilot line
Pressure Side
Valve
normally
closed
Spring loaded
Variable
When open, goes to tank
Valve is
regulated
by the
feed
pressure

14. Pressure Reducing Valve
Pressure Side
Represents the pilot line
Valve
normally
open
Spring loaded
Variable
Discharge side goes to line
Valve is
regulated
by the
discharge
pressure

15. Valves
Relief Valve
Sequencing Valve
Pressure
Reducing/Regulating
Valve

16. Valves
Orifice
V Timing logic
Check valve

17. Valves
Flow control with bypass,
pressure compensated
Flow control with bypass,
pressure and temperature
compensated

18. Valves
Counterbalance Valve
Unloading Valve

19. Controls
Push Button
Lever
Pedal
Cam
Solenoid
Liquid pilot
Gas pilot
Servo
Pilot or solenoid
Pilot and solenoid
activated, spring
return

20. Cylinders
Single acting
Single acting,
spring return
Double acting
Double acting,
double rod
Double acting,
single cushion
Double acting,
Double cushion
Double acting,
double adjustable
cushion
Telescoping
Ram
Pressure
intensifier

21. This workforce solution was funded by a grant awarded by the U.S.
Department of Labor’s Employment and Training Administration.
The solution was created by the grantee and does not necessarily
reflect the official position of the U.S. Department of Labor. The
Department of Labor makes no guarantees, warranties, or
assurances of any kind, express or implied, with respect to such
information, including any information on linked sites, but not limited
to accuracy of the information or its completeness, timeliness,
usefulness, adequacy, continued availability or ownership.
This work is licensed under a Creative Commons CC BY 3.0
Unported License. http://creativecommons.org/licenses/by/3.0/