Hydraulic Schematic Symbols - Standard Symbols - Lines - Circular - Square - Diamond - Miscellaneous - Pumps and Compressors - Motors

Oct 28, 2026

Hydraulic schematic symbols standardize how hydraulic and pneumatic components are represented in diagrams, enabling consistent interpretation of flow, control, and actuation functions. The content covers line types for flow and pilot/drain signals, geometric symbol conventions for pumps, motors, cylinders, and actuators, plus specialized shapes for fluid conditioning devices. It further details directional control valves by port/position counts, electro-hydraulic servo behavior, operator control methods, and key valve families such as check, shuttle, rapid exhaust, pressure relief, proportional relief, sequence, pressure reducing, and flow control.

LanguageEnglish

CategoryTechnology

FormatPDF

Pages8

Reading Time20 min

AccessFree to download

Hydraulic Schematic Symbols

Standard Symbols

Lines and Geometric Symbol Types

Circular, Square, Diamond, and Miscellaneous Symbols

Pumps and Compressors

Motors

Cylinders and Cushions

Directional Control Valves by Ports and Positions

Electro-Hydraulic Servo Valves

Control Methods for Valves

Pressure Control Valves

Flow Control Valves

Hydraulic Schematic Symbols Standard Symbols Connecting Pressure Lines (usually representing plastic tubing for pneumatic [air] lines with low pressures, metal piping for hydraulic [fluid] lines with high pressure) Lines -Continuous line (for) flow line -Dashed line (for) pilot, drain -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 [https://www.airlinehyd.com/pages/resources/hydraulic-schematic-symbols](https://www.airlinehyd.com/pages/resources/hydraulic-schematic-symbols) Pumps and Compressors (turn rotary torque from an AC or DC electric motor into pressure in a hydraulic or pneumatic system) Fixed Displacement Hydraulic Pump Symbols -Unidirectional -Bidirectional Variable Displacement Hydraulic Pump Symbols -Unidirectional -Bidirectional Compressor symbol Motors Fixed Displacement Hydraulic Motor Symbol -Unidirectional -Bidirectional Variable Displacement Hydraulic Motor Symbol -Unidirectional -Bidirectional Pneumatic Motor Symbol -Unidirectional -Bidirectional Rotary Actuator Symbol -Hydraulic -Pneumatic Cylinders Single Acting Cylinder Symbols -Returned by external force -Returned by spring or extended by spring force Double Acting Cylinder Symbols -Single piston rod (fluid required to extend and retract) -Double ended piston rod Cylinders with Cushions Symbols -Single fixed cushion -Double fixed cushion -Single adjustable cushion -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. -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. -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 [https://www.airlinehyd.com/pages/resources/hydraulic-schematic-symbols](https://www.airlinehyd.com/pages/resources/hydraulic-schematic-symbols) Directional Control Valve (4 ports / 3 positions) -Directional control valve with 4 ports and 3 finite positions *-(center position can have various flow paths) Directional control valve (5 ports / 2 positions) Normally a pneumatic valve -Directional control valve with 5 ports and 2 finite positions Directional control valve (5 ports / 3 positions) Normally a pneumatic valve -Directional control valve with 5 ports and 3 finite positions Electro-Hydraulic Servo Valve The spool positions on these valves is variable allowing for variable flow conditions. -Single-stage direct operation unit which accepts an analog signal and provides a similar analog fluid power output -Two-stage with mechanical feedback indirect pilot operation unit which accepts an analog signal and provides a similar analog fluid power output [https://www.airlinehyd.com/pages/resources/hydraulic-schematic-symbols](https://www.airlinehyd.com/pages/resources/hydraulic-schematic-symbols) Control Method-Operator symbols for valves Manual Control -General symbol of a valve's manual operator (without showing the control type) -Pushbutton -Lever -Foot pedal Mechanical Valve Control -Plunger or tracer -Spring (used on one side of a valve to hold it in the normally open or normally closed stat

FAQs

What do continuous and dashed line styles represent in the hydraulic schematic symbols chart?

A continuous line represents a flow line. A dashed line represents pilot and drain signals.

How are directional control valves categorized in the chart?

Directional control valves are described by their number of ports and positions, such as 2 ports/2 positions, 3 ports/2 positions, 4 ports/2 positions, and combinations like 4 ports/3 positions.

What is the difference between a pressure relief valve and a proportional pressure relief valve?

A pressure relief valve limits line pressure to a set setting and directs the secondary path to the tank. A proportional pressure relief valve limits line pressure proportionally to an electronic signal.

Oct 28, 2026

Upload by Mafia Boss