All Hydraulic Symbols

1.1 General:

Fluid power systems are those that transmit and control power through use of a pressurized fluid (liquid or gas) within an enclosed circuit. Types of symbols commonly used in drawing circuit diagrams for fluid power systems are Pictorial, Cutaway, and Graphic. These symbols are fully explained in the USA Standard Drafting Manual (Ref. 2).
1.1.1 Pictorial symbols are very useful for showing the interconnection of components. They are difficult to standardize from a functional basis.
1.1.2 Cutaway symbols emphasize construction. These symbols are complex to draw and the functions are not readily apparent.
1.1.3 Graphic symbols emphasize the function and methods of operation of components. These symbols are simple to draw. Component functions and methods of operation are obvious. Graphic symbols are capable of crossing language barriers, and can promote a universal understanding of fluid power systems. Graphic symbols for fluid power systems should be used in conjunction with the graphic symbols for other systems published by the USA Standards Institute (Ref. 37 inclusive). Complete graphic symbols are those, which give symbolic representation of the component and all of its features pertinent to the circuit diagram. Simplified graphic symbols are stylized versions of the complete symbols. Composite graphic symbols are an organization of simplified or complete symbols. Composite symbols usually represent a complex component.

1.2 Scope and Purpose

1.2.1 Scope – This standard presents a system of graphic symbols for fluid power diagrams. Elementary forms of symbols are: Circles Rectangles Arcs Dots Squares Triangles Arrows Crosses Symbols using words or their abbreviations are avoided. Symbols capable of crossing language barriers are presented herein. Component function rather than construction is emphasized by the symbol. The means of operating fluid power components are shown as part of the symbol (where applicable). This standard shows the basic symbols, describes the principles on which the symbols are based, and illustrates some representative composite symbols. Composite symbols can be devised for any fluid power component by combining basic symbols. Simplified symbols are shown for commonly used components. This standard provides basic symbols, which differentiate between hydraulic and pneumatic fluid power media.

1.2.2 Purpose The purpose of this standard is to provide a system of fluid power graphic symbols for industrial and educational purposes. The purpose of this standard is to simplify design, fabrication, analysis, and service of fluid power circuits. The purpose of this standard is to provide fluid power graphic symbols, which are internationally recognized. The purpose of this standard is to promote universal understanding of fluid power systems.

2. Symbol Rules

2.1 Symbols show connections, flow paths, and functions of components represented. They can indicate conditions occurring during transition from on flow path arrangement to another. Symbols do not indicate construction, nor do they indicate values, such as pressure, flow rate, and other component settings.
2.2 Symbols do not indicate locations of ports, direction of shifting spools, or positions of actuators on actual components.
2.3 Symbols may be rotated or reversed without altering their meaning except in the cases of: a.) Lines to Reservoir, 4.1.1; b.) Vented Manifold,; c.) Accumulator, 4.2.

 Solid Line- Mainline
 Dash Line – Pilot
(Pilot line for control)
 dashed line
 Dotted Line
(Exhaust or Drain Line)
 doted lineFixed Pump
Center Line (Enclosure Outline) center lineVariable Pump
 Lines Crossing
(The intersection is not
necessarily at a 90° angle.)
 Lines Joining join
 Plugged port. plug