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Hydraulic Schematic Symbols

Hydraulic Schematic Symbols

Hydraulic_Schematic_Symbols

Use this page as a reference to find common schematic symbols used in fluid power schematics, hydraulic schematics, pneumatic schematics, diagrams, and circuits.

Check out these other fluid power informational links for more information:

Standard Symbols
Lines
continuous line for flow line (Symbol/picture)
Continuous line - for flow line

dashed line for pilot, drain (Symbol/picture)
Dashed line - for pilot, drain

(Envelope) long and short dashes around two or more (Symbol/picture)
Envelope - for long and short dashes around two or more component symbols
Circular
Large Circle - pump, motor

Small Circle - measuring devices

Semi-circle - rotary actuator
Square
One square - pressure control function
Two or three adjacent squares - directional control
Diamond
Diamond - Fluid conditioner (filter, separator, lubricator, heat exchanger)
Miscellaneous Symbols
Spring

Flow Restriction
Triangle
Solid - Direction of Hydraulic Fluid Flow

Open - Direction of Pneumatic flow

Pump and Compressor Symbols
Fixed Displacement Hydraulic Pump Symbols
Fixed Displacement hydraulic pump Schematic Symbol
Unidirectional

Fixed Displacement hydraulic pump (Reversible flow) Schematic Symbol
Bidirectional
Variable Displacement Hydraulic Pump Symbols
Unidirectional

Variable displacement hydraulic pump Schematic Symbol
Bidirectional

Variable displacement hydraulic pump (Reversible flow) Schematic Symbol
Semi-circle - rotary actuator
Compressor Symbol
Compressor Schematic Symbol

Motor Symbols
 
Fixed Displacement Hydraulic Motor Symbols
Fixed displacement hydraulic motor Schematic Symbol
Unidirectional

Fixed displacement hydraulic motor (Reversible/bidirectional) Schematic Symbol
Bidirectional
Variable Displacement Hydraulic Motor Symbols
Variable displacement hydraulic motor Schematic Symbol
Unidirectional

Variable displacement hydraulic motor (Reversible/bidirectional) Schematic Symbol
Bidirectional
Pneumatic Motor Symbols
Pneumatic motor Schematic Symbol
Unidirectional

Pneumatic motor Schematic Symbol
Bidirectional
Rotary Actuator Symbols
Rotary Actuator hydraulic Schematic Symbol
Hydraulic

Rotary Actuator pneumatic Schematic Symbol
Pneumatic

Cylinder Symbols
 
Single Acting Cylinder Symbols
Single acting cylinder symbol (pilot return) Schematic Symbol
Returned by external force

Single acting cylinder symbol (spring Return) Schematic Symbol
Returned by spring or extended by spring force
Double Acting Cylinder Symbols
Double acting cylinder symbol (single piston rod) Schematic Symbol
Single piston rod (fluid required to extend and retract)

Double acting cylinder symbol (double ended piston rod) Schematic Symbol
Double ended piston rod
Cylinders with Cushions Symbols
Cylinders with a single fixed cushion Schematic Symbol
Single fixed cushion

Cylinders with a double fixed cushion Schematic Symbol
Double fixed cushion
Cylinders with Cushions Symbols
Cylinders with a single fixed cushion Schematic Symbol
Single fixed cushion

Cylinders with a double fixed cushion Schematic Symbol
Double fixed cushion

Cylinders with a single adjustable cushion Schematic Symbol
Single adjustable cushion

Cylinders with a double adjustable cushion Schematic Symbol
Double adjustable cushion

Directional Control Valve Symbols
Directional Control Valve (2 ports / 2 positions)
Normally closed, directional control valve with 2 ports and 2 finite positions (Schematic Symbol)
Normally closed directional control valve with 2 ports and 2 finite positions

Normally open, directional control valve with 2 ports and 2 finite positions. (Schematic Symbol)
Normally open directional control valve with 2 ports and 2 finite positions
Directional Control Valve (3 ports / 2 positions)
Normally closed, directional control valve with 3 ports and 2 finite positions. (Schematic Symbol)
Normally closed directional control valve with 3 ports and 2 finite positions

Normally open, directional control valve with 3 ports and 2 finite positions. (Schematic Symbol)
Normally open directional control valve with 3 ports and 2 finite positions
Directional Control Valve (4 ports / 2 positions)
directional control valve with 4 ports and 2 finite positions. (Schematic Symbol)
Directional control valve with 4 ports and 2 finite positions
Directional Control Valve (4 ports / 3 positions)
directional control valve with 4 ports and 3 finite positions. (Schematic Symbol)
Directional control valve with 4 ports and 3 finite positions (center position can have various flow paths)
Directional control valve (5 ports / 2 positions)
directional control valve with 5 ports and 2 finite positions. (Schematic Symbol)
Directional control valve with 5 ports and 2 finite positions
Directional control valve (5 ports / 3 positions)
directional control valve with 5 ports and 3 finite positions. (Schematic Symbol)
Directional control valve with 5 ports and 3 finite positions
Electro-Hydraulic Servo Valve
single-stage Electro-hydraulic servo valve, direct operation unit which accepts an analog signal and provides a similar analog fluid power output (Schematic Symbol)
Single-stage direct operation unit which accepts an analog signal and provides a similar analog fluid power output

two-stage Electro-hydraulic servo valve with mechanical feedback indirect pilot operation unit which accepts an analog signal and provides a similar analog fluid power output (Schematic Symbol)
Two-stage with mechanical feedback indirect pilot operation unit which accepts an analog signal and provides a similar analog fluid power output

Control Method - Operator Symbols for Valves
Manual Control
general symbol of a Valve's Manual Operator (without showing the control type) (Schematic Symbol)
General symbol of a valve's manual operator (without showing the control type)

symbol for a pushbutton Valve's Operator (Schematic Symbol)
Pushbutton

symbol for a lever Valve's Operator (Schematic Symbol)
Lever

symbol for a foot pedal Valve's Operator (Schematic Symbol)
Foot pedal
Mechanical Valve Control
symbol for a plunger Valve's Operator (Schematic Symbol)
Plunger or tracer

symbol for a Valve with spring return on one side (Schematic Symbol)
Spring (used on one side of a valve to hold it in the normally open or normally closed state)

symbol for a roller Valve's Operator (Schematic Symbol)
Roller

symbol for a roller Valve's (one direction only) type Operator (Schematic Symbol)
Roller (one direction only)
Electrical/Solenoid Valve Control
symbol for a Solenoid Valve's Operator (Schematic Symbol)
Solenoid (the one side's winding shown)
Pilot Operation (uses pressure to actuate valve)
symbol for a pneumatically actuated pilot Valve's Operator (Schematic Symbol)
Pneumatic actuated pilot

symbol for a hydraulically actuated pilot Valve's Operator (Schematic Symbol)
Hydraulic actuated pilot
Pilot operated two-stage valve (uses a second lesser force to actuate the pilot actuation of the valve)
symbol for a two-stage piloted (Pneumatic: Solenoid first stage) Valve's Operator (Schematic Symbol)
Pneumatic: Solenoid first stage

symbol for a two-stage piloted (Pneumatic: Air pilot second stage) Valve's Operator (Schematic Symbol)
Pneumatic: Air pilot second stage

symbol for a two-stage piloted (Hydraulic: Solenoid first stage) Valve's Operator (Schematic Symbol)
Hydraulic: Solenoid first stage

symbol for a two-stage piloted (Hydraulic: Hydaulic pilot second stage) Valve's Operator (Schematic Symbol)
Hydraulic: Hydaulic pilot second stage

Check Valve, Shuttle Valve, & Rapid Exhaust Valve Symbols

symbol for a Check Valve (Schematic Symbol)
Check valve symbol-free flow one direction, blocked flow in other direction

symbol for a pilot operated check valve, pilot to close (Schematic Symbol)
Pilot operated check valve symbol, pilot to close

symbol for a pilot operated check valve symbol, pilot to open (Schematic Symbol)
Pilot operated check valve symbol, pilot to open
Shuttle Valve
symbol for a shuttle valve (Schematic Symbol)
To isolate one part of a system from an alternate part of circuit.
Rapid Exhaust Valve/Pneumatic
symbol for a Solenoid Valve's Operator (Schematic Symbol)
Solenoid (the one side's winding shown)

Pressure Control Valve Symbols
Pressure Relief Valve (Safety Valve) normally closed
symbol for a Pressure Relief Valve(safety valve) normally closed (Schematic Symbol)
Line pressure is limited to the setting of the valve, secondary part is directed to tank
Proportional Pressure Relief Valve
symbol for a Proportional Pressure Relief Valve (Schematic Symbol)
Line pressure is limited to and proportional to an electronic signal
Sequence Valve
symbol for a Sequence Valve (Schematic Symbol)
When the line pressure reaches the setting of the valve, valve opens permitting flow to the secondary port. The pilot must be externally drained to tank
Pressure Reducing Valve (Hydraulic Pressure Regulator)
symbol for a Pressure Reducing valve (Pressure Regulator) (Schematic Symbol)
Pressure downstream of valve is limited to the setting of the valve

Flow Control Valve Symbols
Throttle Valve
symbol for a Throttle valve (Schematic Symbol)
Adjustable output flow
Flow Control Valves
symbol for a Flow Control valve(variable inlet pressure) (Schematic Symbol)
Flow control valve with fixed output (variations in inlet pressure do not affect rate of flow)

symbol for a Flow Control valve(with fixed output and relief port to reservoir with relief for excess flow [variations in inlet pressure do not affect rate of flow] ) (Schematic Symbol)
Flow control valve with fixed output and relief port to reservoir with relief for excess flow (variations in inlet pressure do not affect rate of flow)

symbol for a Flow Control valve(with variable output) (Schematic Symbol)
Flow control valve with variable output

symbol for a Flow Control valve(fixed orifice) (Schematic Symbol)
Flow control valve with fixed orifice

symbol for a Flow Control valve(metered flow toward right free flow to left) (Schematic Symbol)
Flow control valve with metered flow toward right free flow to left

symbol for a Flow Control valve(pressure compensated flow control fixed output flow regardless of load) (Schematic Symbol)
Flow control valve with pressure compensated flow control fixed output flow regardless of load

symbol for a Flow Control valve(pressure and temperature compensated) (Schematic Symbol)
Flow control valve with pressure and temperature compensated

symbol for a Flow Control valve(variable output and relief port to reservoir) (Schematic Symbol)
Flow control valve with variable output and relief port to reservoir
Flow Dividing Valve
symbol for a Flow divider (Schematic Symbol)
Flow is divided equally to two outputs

Shut-Off Vlave Symbols

symbol for a Shut-Off Valve (Schematic Symbol)
Shut-Off valve simplified symbol

Accumulator Symbols

symbol for an Accumulator (Schematic Symbol)
Accumulator symbol (stores pressure)

Reservoir Symbols

symbol for your tank or resorvoir (Schematic Symbol)
Reservoir symbol (holds fluid medium of your system)

Filter, Water Trap, Lubricator, and Miscellaneous Apparatus Symbols
Filter or Strainer
symbol for a Filter or Strainer (Schematic Symbol)
Filter or Strainer
Water Trap
symbol for a Water Trap (with manual drain) (Schematic Symbol)
With manual drain

symbol for a Water Trap (with automatic drained) (Schematic Symbol)
With automatic drained
Filter with Water Trap
symbol for a Filter with water trap (with manual drain) (Schematic Symbol)
With manual drain

symbol for a Filter with water trap (with automatic drained) (Schematic Symbol)
Automatic drain
Air Dryer
symbol for an Air Dryer (refrigerant, or chemical removal of water from compressed air line) (Schematic Symbol)
Refrigerant, or chemical removal of water from compressed air line
Lubricator
symbol for a Lubricator (oil vapor is injected into air line) (Schematic Symbol)
Oil vapor is injected into air line
Conditioning Unit (FRL, Pressure Regulator)
symbol for a Conditioning unit (Pneumatic Pressure Regulator) (FRL compound symbol of filter, regulator, lubricator unit) (Schematic Symbol)
Compound symbol of filter, regulator, lubricator unit (FRL symbol)

symbol for a Conditioning unit (Pneumatic Pressure Regulator) (FRL compound symbol of filter, regulator, lubricator unit) (Simplified Schematic Symbol)
Simplified Symbol

Heat Exchanger Symbols

symbol for a Heat Exchanger (Schematic Symbol)
Air or water cooled unit designed to remove heat from oil returning to reservoir

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