Appendix: Graphic Symbols for Fluid Power Diagrams

This page provides the Appendix containing graphic symbols for fluid power diagrams from the U.S. Navy's fluid power training course.

Other related chapters from the Navy's fluid power training course can be seen to the right.

Fluid Connectors

Line, Working (Main) Line, Working (Main)
Line, Pilot (for Control) Line, Pilot (for Control)
Line, Exhaust and Liquid Drain Line, Exhaust and Liquid Drain
Flow, Direction of (Hydraulic) Flow, Direction of (Hydraulic)
Line, Flexible Line, Flexible
Quick Disconnect, Without Checks (Connected) Quick Disconnect, Connected
Quick Disconnect, Without Checks (Disconnected) Quick Disconnect, Disconnected
Line, with Fixed Restriction Line, with Fixed Restriction
Lines, Crossing Lines, Crossing
Lines, Joining Lines, Joining

Energy Storage & Fluid Storage

Reservoir, Vented Reservoir, Vented
Reservoir, Pressurized Pressurized
Reservoir with Connecting Lines Above Fluid Level Above Fluid Level
Accumulator Accumulator
Accumulator, Spring Loaded Accumulator, Spring Loaded
Accumulator, Gas Charged Accumulator, Gas Charged
Accumulator, Weighted Accumulator, Weighted
Energy Source, Hydraulic
(Pump, Compressor, Accumulator, etc.)
Energy Source, Hydraulic

Fluid Conditioners

Filter-Strainer Filter-Strainer
Cooler
(inside triangles indicate heat dissipation)
Cooler
Cooler
(outside tringles indicate cooling medium is liquid)
Cooler (liquid cooling medium)
Cooler
(outside tringles indicate cooling medium is gaseous)
Cooler (gaseous cooling medium)
Heater
(inside triangles indicate heat introduction)
Heater
Heater
(outside tringles indicate heating medium is liquid)
Heater (liquid heating medium)
Heater
(outside tringles indicate heating medium is gaseous)
Heater (gaseous heating medium)
Dessicator (Chemical Dryer) Dessicator (Chemical Dryer)

Linear Devices

Cylinder (Hydraulic & Pneumatic), Single Acting Cylinder (Hydraulic & Pneumatic), Single Acting
Cylinder (Hydraulic & Pneumatic), Double Acting, Single End Rod Cylinder (Hydraulic & Pneumatic), Double Acting, Single End Rod
Cylinder (Hydraulic & Pneumatic), Double Acting, Double End Rod Cylinder (Hydraulic & Pneumatic), Double Acting, Double End Rod

Actuators and Controls

Spring Spring
Manual
(general symbol without indicating specific type, i.e. foot, hand, leg, arm, etc.)
Manual Control
Push Button Push Button
Mechanical Mechanical
Detent Detent
Pressure Compensated Pressure Compensated
Electrical Solenoid (Single Winding) Electrical Solenoid (Single Winding)
Pilot Pressure, Remote Supply Pilot Pressure, Remote Supply
Pilot Pressure, Internal Supply Pilot Pressure, Internal Supply
Solenoid or Pilot, External Pilot Supply Solenoid or Pilot, External Pilot Supply
Internal Pilot, Supply and Exhaust Internal Pilot, Supply and Exhaust

Rotary Devices

Hydraulic Pump, Fixed Displacement, Unidirectional Hydraulic Pump, Fixed Displacement, Unidirectional
Hydraulic Pump, Fixed Displacement, Bidirectional Hydraulic Pump, Fixed Displacement, Bidirectional
Hydraulic Pump, Variable Displacement, Non Compensated, Unidirectional Hydraulic Pump, Variable Displacement, Non Compensated, Unidirectional
Hydraulic Pump, Variable Displacement, Non Compensated, Bidirectional Hydraulic Pump, Variable Displacement, Non Compensated, Bidirectional
Hydraulic Pump, Variable Displacement, Pressure Compensated, Unidirectional Hydraulic Pump, Variable Displacement, Pressure Compensated, Unidirectional
Hydraulic Pump, Variable Displacement, Pressure Compensated, Bidirectional Hydraulic Pump, Variable Displacement, Pressure Compensated, Bidirectional
Hydraulic Motor, Fixed Displacement Hydraulic Motor, Fixed Displacement
Electric Motor Electric Motor
Heat Engine
(e.g. internal combustion engine)
Heat Engine

Instruments & Accessories

Indicating & Recording

Pressure Pressure
Temperature Temperature
Flow Rate Meter Flow Rate Meter

Accessories

Pressure Switch Pressure Switch

Valves

Two Way Valves (2 Ported Valves)

On-Off Valve (Manual Shut-Off) On-Off Valve (Manual Shut-Off)
Check Valve Check Valve
Check Valve, Pilot Operated to Open Check Valve, Pilot Operated to Open
Check Valve, Pilot Operated to Close Check Valve, Pilot Operated to Close

Pressure Control Valves

Pressure Relief Valve Pressure Relief Valve
Sequence Valve Sequence Valve

Four Way Valves

Servovalve, Variable Position
(indicated by parallel lines)
Servovalve, Variable Position
Two Position, Normal Four Way Valve, Two Position, Normal
Two Position, Actuated Four Way Valve, Two Position, Actuated
Three Position, Normal Four Way Valve, Three Position, Normal
Three Position, Actuated Left Four Way Valve, Three Position, Actuated Left
Three Position, Actuated Right Four Way Valve, Three Position, Actuated Right
Typical Flow Paths for Center Condition of Three Position Valves Typical Flow Paths for Center Condition of Three Position Valves

Flow Control Valves

Adjustable, Non Compensated
(Flow Control in Each Direction)
Adjustable, Non Compensated
Adjustable, Temperature & Pressure Compensated Adjustable, Temperature and Pressure Compensated