INTERSTATE STANDARD
UNIFIED SYSTEM OF DESIGN DOCUMENTATION
CONDITIONAL GRAPHIC SYMBOLS.
HYDRAULIC AND PNEUMATIC MACHINES
GOST 2.782-96
INTERSTATE COUNCIL FOR STANDARDIZATION,
METROLOGY AND CERTIFICATION
Minsk
PREFACE.
1. DEVELOPED by the Research and Design Institute of Industrial Hydraulic Drives and Hydroautomatics (NIIGidroprivod), the All-Russian Research Institute for Standardization and Certification in Mechanical Engineering (VNIINMASH).
INTRODUCED by Gosstandart of Russia.
2. ADOPTED by the Interstate Council for Standardization, Metrology and Certification (Minutes No. 10 of October 4, 1996).
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State name |
Name of the national standardization body |
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The Republic of Azerbaijan |
Azgosstandart |
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Republic of Armenia |
Armstate standard |
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Republic of Belarus |
Belstandard |
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The Republic of Kazakhstan |
State Standard of the Republic of Kazakhstan |
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Kyrgyz Republic |
Kyrgyzstandart |
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The Republic of Moldova |
Moldovastandard |
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Russian Federation |
Gosstandart of Russia |
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The Republic of Tajikistan |
Tajik state center for standardization, metrology and certification |
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Turkmenistan |
Turkmenglavstate inspection |
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State Standard of Ukraine |
3. This standard complies with ISO 1219-91 “Hydraulic drive, pneumatic drive and devices. Conditional graphic designations and schemes. Part 1. Conditional graphic symbols» in terms of hydraulic and pneumatic machines.
4. Decree of the State Committee Russian Federation on standardization, metrology and certification dated April 7, 1997 No. 123, the interstate standard GOST 2.782-96 was put into effect directly as the state standard of the Russian Federation from January 1, 1998.
5. REPLACE GOST 2.782-68.
GOST 2.782-96
INTERSTATE STANDARD
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Unified system of design documentation. CONDITIONAL GRAPHIC SYMBOLS. MACHINES HYDRAULIC AND PNEUMATIC. Unified system for design documentation. |
Introduction date 1998-01-01
1 AREA OF USE.
This standard establishes the conventional graphic symbols for hydraulic and pneumatic machines (pumps, compressors, motors, cylinders, rotary motors, converters, displacers) in diagrams and drawings of all industries.
2. REGULATORY REFERENCES.
GOST 17398-72 Pumps. Terms and Definitions.
GOST 17752-81 Volumetric hydraulic drive and pneumatic drive. Terms and Definitions.
GOST 28567-90 Compressors. Terms and Definitions.
3. DEFINITIONS.
This standard uses the terms according to GOST 17752, GOST 17398 and GOST 28567.
4. MAIN PROVISIONS.
4.1. Designations reflect the purpose (action), the way the devices work and external connections.
4.2. Symbols do not show actual design devices.
4.3. The letters used in the symbols are only alphabetic symbols and do not represent parameters or parameter values.
4.4. Unless otherwise specified, symbols may be drawn in any position, as long as their meaning is not distorted.
4.5. The size of symbols is not set by the standard.
4.6. The designations built according to functional features must correspond to those given in Table 1.
If it is necessary to reflect the principle of operation, then the notation given in.
4.7. Rules and examples of designations for the relationship between the direction of rotation, the direction of flow of the working medium and the position control devices for pumps and motors are given in and .
Table 1
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Name |
Designation |
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1. The pump is unregulated: With irreversible flow |
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Reverse flow |
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2. Pump adjustable: With irreversible flow |
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Reverse flow |
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3. Pump adjustable with manual control and one direction of rotation |
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4. Single direction pressure regulated pump with adjustable spring and drain (see and ) |
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5. Dosing pump |
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6. Multi-outlet pump (for example, a three-way variable pump with one plugged outlet) |
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7. Hydraulic motor unregulated: With irreversible flow |
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Reverse flow |
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8. Adjustable hydraulic motor: Irreversible flow, unspecified control mechanism, external drain, one direction of rotation and two shaft ends |
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9. Rotary hydraulic motor |
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10. Compressor |
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11. Pneumomotor unregulated: With irreversible flow |
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Reverse flow |
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12. Adjustable pneumatic motor: With irreversible flow |
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Reverse flow |
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13. Rotary air motor |
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14. Pump-motor unregulated: |
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With any flow direction |
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15. Pump-motor adjustable: With the same direction of flow |
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With reverse flow direction |
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With any direction of flow, with manual control, external drain and two directions of rotation |
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16. Pump-motor adjustable, with two directions of rotation, spring zero centering working volume, external control and drainage (signal n causes movement in the direction N) (mass media ) |
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17. Volumetric hydraulic transmission: With fixed pump and motor, one direction of flow and one direction of rotation |
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Variable pump, flow reversible, bi-directional, variable speed |
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With fixed pump and one direction of rotation |
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18. Single acting cylinder: Piston without specifying the method of return of the rod, pneumatic |
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Piston with spring return, pneumatic |
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Piston with spring extension, hydraulic |
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Plunger |
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Telescopic with one-way extension, pneumatic |
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19. Double acting cylinder: Single rod, hydraulic |
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Double-acting, pneumatic |
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Telescopic with one-way extension, hydraulic |
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Telescopic with double-sided extension |
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20. Differential cylinder (the ratio of the areas of the piston from the side of the rod and non-rod cavities is of paramount importance) |
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21. Double-acting cylinder with the supply of the working medium through the rod: With unilateral stem |
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With double ended stem |
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22. Double-acting cylinder with constant braking at the end of the stroke: Piston side |
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From two sides |
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23. Double-acting cylinder with adjustable end-of-stroke braking: Piston side |
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On both sides and 2:1 area ratio Note - If necessary, the ratio of the annular area of the piston to the area of the piston (area ratio) can be given above the piston symbol. |
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24. Two-chamber double-acting cylinder |
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25. Diaphragm cylinder: Single acting |
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Double acting |
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26. Pneumohydraulic displacer with separator: Translational |
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rotational |
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27. Translational transducer: |
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28. Rotary transducer: With one kind of working environment |
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With two kinds of working environment |
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29. Cylinder with built-in mechanical locks |
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Name |
Designation |
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1. Manual pump |
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2. Gear pump |
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3. Screw pump |
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4. Vane pump |
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5. Radial piston pump |
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6. Axial piston pump |
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7. Crank pump |
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8. Centrifugal vane pump |
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9. Jet pump: General designation |
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With liquid external flow |
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With gas external flow |
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10. Fan: Centrifugal |
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APPENDIX A
(recommended)
RULES FOR DESIGNATION OF ROTATION DIRECTION DEPENDENCE ON WORKING FLOW DIRECTION AND CONTROL DEVICE POSITION FOR HYDRO- AND PNEUMATIC MACHINES.
A.1. The direction of rotation of the shaft is shown by a concentric arrow around the main designation of the machine from the power supply element to the power output element. For devices with two directions of rotation, only one arbitrarily chosen direction is shown. For devices with double shaft the direction is shown at one end of the shaft.
A.2. For pumps, the arrow starts at drive shaft and ends with a tip at the outlet flow line.
A.3. For motors, the arrow starts at the inlet flow line and ends with the point of the arrow at the output shaft.
A.4. For motor pumps according to A.2 and A.3.
A.5. If necessary, the corresponding designation of the position of the control device is shown near the tip of the concentric arrow.
A.6. If the control characteristics are different for the two directions of rotation, information is shown for both directions.
A.7. A line showing the positions of the control device and designations of positions (for example, M - Æ - N) is applied perpendicular to the control arrow. The sign Æ denotes the position of the zero working volume, the letters M And N indicate the extreme positions of the control device for the maximum displacement. It is preferable to use the same designations that are printed on the body of the device.
The point of intersection of the arrow showing regulation and perpendicular to the line indicates the position "in stock" (Figure 1).
Picture 1.
APPENDIX B
(recommended)
EXAMPLES OF DESIGNATION OF ROTATION DIRECTION DEPENDENCE ON WORKING FLOW DIRECTION AND CONTROL DEVICE POSITIONS FOR HYDRO AND PNEUMATIC MACHINES.
Table B.1
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Name |
Designation |
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1. Single-functional device (motor). The hydraulic motor is unregulated, with one direction of rotation. |
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2. Single-functional device (machine). The hydraulic machine is unregulated, with two directions of rotation. |
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3. Single-functional device (pump). The hydraulic pump is adjustable (with a change in working volume in one line), with one direction of rotation. The designation of the position of the control device can be omitted, it is shown in the figure for clarity only. |
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4. Single-functional device (motor). The hydraulic motor is adjustable (with a change in working volume in one direction), with two directions of rotation. One direction of rotation is shown, related to the direction of flow. |
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5. Single-functional device (machine). The hydraulic machine is adjustable (with a change in working volume in both directions), with one direction of rotation. The direction of rotation and the corresponding position of the control device are shown in relation to the direction of flow. |
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6. Single-functional device (machine). The hydraulic machine is adjustable (with a change in the working volume in both directions), with two directions of rotation. Shown is one direction of rotation and the corresponding position of the control device associated with the direction of flow. |
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7. Pump-motor. The pump-motor is unregulated with two directions of rotation. |
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8. Pump-motor. The pump-motor is adjustable (with a change in working volume in one direction), with two directions of rotation. One direction of rotation is shown, related to the direction of flow, when operating in pump mode. |
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9. Pump-motor. The pump-motor is adjustable (with a change in the working volume in both directions), with one direction of rotation. Shows the direction of rotation and the corresponding position of the control device, related to the direction of flow, when operating in pump mode. |
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10. Pump-motor. Pump-motor adjustable (with the use of a working volume in both directions, with two directions of rotation. Shown is one direction of rotation and the corresponding position of the control device associated with the direction of flow when operating in pump mode. |
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Motor with two directions of rotation: adjustable (with change of displacement in one line) in one direction of rotation, non-adjustable in the other direction of rotation. Both possibilities are shown. |
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Keywords: conditional graphic symbols, hydraulic and pneumatic machines
The hydraulic diagram is an element of technical documentation, which, using symbols, shows information about the elements hydraulic system, and the relationship between them.
According to ESKD hydraulic diagrams are designated in the cipher of the main inscription by the letter "G" (- by the letter "P").
As can be seen from the definition, hydraulic scheme conditionally shows the elements that are interconnected by pipelines - designated lines. Therefore, in order to correctly read the hydraulic circuit, you need to know how this or that element is indicated on the diagram. Symbols for elements are indicated in GOST 2.781-96. Study this document and you will be able to find out how the main elements of hydraulics are indicated.
Designations of hydraulic elements on the diagrams
Consider the main elements hydraulic circuits.
Pipelines
The pipelines on the hydraulic diagrams are shown with solid lines connecting the elements. Control lines are usually shown as a dotted line. The directions of fluid movement, if necessary, can be indicated by arrows. Often on hydraulic diagrams they indicate lines - a letter P denotes the pressure line, T - drain, X - control, l - drainage.
The connection of lines is shown with a dot, and if the lines intersect in the diagram, but are not connected, the intersection point is indicated by an arc.
Tank
Tank in hydraulics - important element, which is the repository hydraulic fluid. A tank connected to the atmosphere is shown on the hydraulic diagram as follows.
A closed tank or container, such as a hydraulic accumulator, is shown as a closed loop.
Shown below scheme hydraulic drive , allowing you to move the rod of the hydraulic cylinder, with the possibility of charging the accumulator.
Why is a hydraulic circuit needed?
The hydraulic diagram consists of simple graphical symbols for components, controls and connections. Drawing details has become more convenient, and symbols are more versatile. Therefore, when learning, everyone can understand the notation of the system. A hydraulic diagram is usually preferred for device explanation and troubleshooting.
The two drawings show that the top one is the hydraulic circuit of the bottom drawing. Comparing the two figures, note that the hydraulic diagram does not show the design features or the relative position of the circuit components. The purpose of a hydraulic diagram is to show the purpose of components, connections, and flow lines.
Pump symbols
The main pump symbol is a circle with a black triangle pointing outward from the center. The pressure line comes out of the top of the triangle, the suction line is opposite.
So the triangle shows the direction of the flow.
This symbol indicates a constant displacement pump.
The variable displacement pump is indicated in the figure with an arrow passing through the circle at an angle of 15°
Drive Symbols
Motor symbol
The symbol for the motor is a circle with black triangles, but the apex of the triangle points towards the center of the circle to show that the motor is receiving pressure energy.
Two triangles are used to represent a variable flux motor.
A variable displacement motor with reversal of flow direction is indicated with an arrow passing through the circle at an angle of 45°
Cylinder symbols
The cylinder symbol is a rectangle representing the cylinder body (cylinder) with inline piston and rod symbols. The symbol indicates the position of the cylinder rod in a certain position.
Cylinder double action
This symbol has a closed cylinder and has two matching lines, indicated by lines in the figure.
Single acting cylinder
Only one line, indicated in the figure by a line, is supplied to the single-acting cylinders, the opposite side of the figure is open.
Flow direction
The direction of flow to and from the drive (reversible motor or double acting cylinder) is shown depending on which line the drive fits into. An arrow is used to indicate flow.
Valve symbols - 1
1) Control valve
The basic symbol for a control valve is a square with outlets and an arrow inside to indicate the direction of flow. Usually, a control valve is controlled by a balance of pressure and spring, so in the diagram we show the spring on one side and the pilot line on the other side.
Normally closed valve
A normally closed valve, such as a relief valve, is indicated by a counterweight arrow from the ports directly to the pilot pressure line. This indicates that the spring holds the valve closed until the pressure overcomes the resistance of the spring. We mentally draw an arrow, connecting the flow from the inlet to the outlet, when the pressure increases to the value of overcoming the tension of the spring.
Safety valve
The figure shows a safety valve with a normally closed symbol, connected between the pressure line and the tank. When the pressure in the system exceeds the spring tension, the oil goes into the tank.
Note:
The symbol does not indicate whether this is a simple or complex relief valve. This is important for indicating their functions in the circuit.
The working process:
(a) The valve always remains closed
(b) When pressure appears in the main circuit, the same pressure acts on the valve through the pilot line and when this pressure overcomes the resistance of the spring, the valve opens and oil flows into the tank, thereby reducing the pressure in the main circuit.
Normally open valve
When the arrow connects the inlet and outlet ports, the valve is normally open. The valve closes when the pressure overcomes the resistance of the spring.
The pressure reducing valve is normally open and labeled as shown in the figure below. Outlet pressure is shown against the spring to set or interrupt flow when the spring compression is reached.
The working process:
(a) Oil flows from the pump to the main circuit and A
(b) When outlet pressure valve rises above the set pressure, the oil flow from the pump is stopped and the pressure in circuit A is maintained. It is not affected by main circuit pressure.
(c) When the pressure in circuit A drops, the valve returns to state (a). Therefore, the pressure in circuit A is maintained because conditions (a) and (b) are protected.
Valve symbols - 2
2) FLOW CONTROL VALVE
check valve
The check valve opens to allow oil to flow in one direction and closes to prevent oil from flowing in the opposite direction.
Spool valve
Distribution symbol spool valve uses a complex closed system that has a separate rectangle for each position.
Four port valve
Typically a four port valve has two compartments if the valve has two positions or three compartments if the valve has a center position.
Lever control symbols
Lever control symbols display the lever, pedal, mechanical controls or pilot line located on the edge of the compartment.
Valve symbols - 3
3) HITACHI FOUR FLOW DIRECTION VALVE
Symbols for 4-Way Direction Valve Hitachi is similar to the 4-way symbol, but with connections and flow ports added to show a bypass port.
Symbols for cylinder and motor spools are shown in the figure. Please note that these symbols only show spools. Block control valves also shows relief valves and body connections.
4) REDUCER VALVE
The relief valve symbol is shown in the figure and includes a normally closed valve with a built-in check valve.
The working process:
The pressure reducing valve is installed on the winch motor of the hydraulic crane.
(a) When the load is lowered, back pressure is created because there is a check valve.
(b) The pressure in the discharge line increases, the pilot line opens the valve to direct the flow of oil from the motor through the valve into the drain line. Thus, there is protection against free fall of the load.
The hydraulic scheme is an element of technical documentation, which, using symbols, shows information about the elements of the hydraulic system, and the relationship between them.
According to the ESKD standards, hydraulic circuits are designated in the main inscription code with the letter "G" ( pneumatic diagrams- the letter "P").
As can be seen from the definition, hydraulic scheme conditionally shows the elements that are interconnected by pipelines - designated lines. Therefore, in order to correctly read the hydraulic circuit, you need to know how this or that element is indicated on the diagram. Symbols of elements are specified in GOST 2.781-96. Study this document and you will be able to find out how the main elements of hydraulics are indicated.
Designations of hydraulic elements on the diagrams
Consider the main elements hydraulic circuits.
Pipelines
The pipelines on the hydraulic diagrams are shown with solid lines connecting the elements. Control lines are usually shown as a dotted line. The directions of fluid movement, if necessary, can be indicated by arrows. Often on hydraulic diagrams they indicate lines - a letter P denotes the pressure line, T - drain, X - control, l - drainage.
The connection of lines is shown with a dot, and if the lines intersect in the diagram, but are not connected, the intersection point is indicated by an arc.
Tank
The tank in hydraulics is an important element that is the storage of hydraulic fluid. A tank connected to the atmosphere is shown on the hydraulic diagram as follows.
A closed tank or container, such as a hydraulic accumulator, is shown as a closed loop.
In the designation of the filter, the rhombus symbolizes the body, and the dashed line symbolizes the filter material or filter element.
Pump
Several types of pump designations are used on hydraulic diagrams, depending on their types.
Centrifugal pumps are usually depicted as a circle, in the center of which a suction line is connected, and a discharge line is connected to the perimeter of the circle:
Volumetric(gear, piston, lamellar, etc.) pumps denoted by a circle, with an arrow triangle indicating the direction of fluid flow.
If two arrows are shown on the pump, then this unit is reversible and can pump fluid in both directions.
If the designation is crossed out with an arrow, then the pump is adjustable, for example, the volume of the working chamber can change.
hydraulic motor
The designation of the hydraulic motor is similar to the designation of the pump, only the triangle-arrow is deployed. IN this case the arrow shows the direction of fluid supply to the gyromotor.
The same rules apply for designating a hydraulic motor as for designating a pump: reversibility is indicated by two triangular arrows, the possibility of regulation by a diagonal arrow.
The figure below shows an adjustable reversible pump motor.
Hydraulic cylinder
hydraulic cylinder- one of the most common hydraulic motors, which can be read on almost any hydraulic diagram. The design features of a hydraulic cylinder are usually reflected in the hydraulic diagram, let's look at a few examples.
The double-acting cylinder has supplies to the piston and rod end.
The plunger hydraulic cylinder is depicted on the hydraulic diagrams as follows.
circuit diagram telescopic hydraulic cylinder is shown in the figure.
Distributor
Hydraulic distributor is shown by a set of square windows, each of which corresponds to a certain position of the spool (position). If the distributor is two-position, then in the diagram it will consist of two square windows, a three-position one - of three. Within each box, it shows how the lines are connected at that position.
Consider an example.
The figure shows four linear (four lines A, B, P, T are connected to the distributor), three position (three windows) distributor. The diagram shows the neutral position of the distributor spool, in this case it is in central position(lines are drawn to the central window). Also, the diagram shows how the hydraulic lines are connected to each other, in this example in the neutral position lines P and T are interconnected, A and B are muffled.
As you know, the distributor, switching, can connect different lines, this is shown in the hydraulic diagram.
Consider the left window, which shows that by switching the distributor will connect lines P and B, A and T. This conclusion can be made by virtually moving the distributor to the right.
The remaining position is shown in the right window, connected lines P and A, B and T.
The following video shows the principle of operation of the hydraulic valve.
Understanding the principle of the distributor, you can easily read hydraulic diagrams that include this element.
Control devices
In order to control an element, such as a distributor, you need to influence it in some way.
Shown below conventions: manual, mechanical, hydraulic, pneumatic, electromagnetic control and spring return.
These elements can be arranged in various ways.
The following figure shows four-line, two-position valve, with electromagnetic control and spring return.
Valve
Valves in hydraulics are usually shown as a square, which symbolically shows the behavior of the elements when actuated.
Safety valve
The figure shows the symbol safety valve. The diagram shows that as soon as the pressure in the control line (shown by the dotted line) exceeds the setting of the adjustable spring, the arrow will move to the side and the valve will open.
pressure reducing valve
Also in hydraulic and pneumatic systems quite common pressure reducing valves, the control pressure in such valves is the pressure in the outlet line (at the outlet of the pressure reducing valve).
An example of a designation for a pressure reducing valve is shown in the following figure.
Open valve
Purpose check valve- to pass liquid in one direction, and to block its movement in another. This is also reflected in the diagram. In this case, when flowing from top to bottom, the ball (circle) will move away from the saddle, indicated by two lines. And when the liquid is supplied from below - up, the ball will press against the seat, and will not allow the flow of liquid in this direction.
Check valve diagrams often show a spring under the ball to provide preload.
Throttle - adjustable hydraulic resistance.
Hydraulic resistance or non-adjustable throttle in the diagrams is represented by two curved lines. The possibility of regulation, as usual, is indicated by the addition of an arrow, so an adjustable throttle will be indicated as follows:
Measurement devices
In hydraulics, the most commonly used are: measuring instruments: pressure gauge, flow meter, level indicator, the designation of these devices is shown below.
Pressure switch
This device switches the contact when a certain pressure level is reached. This level is determined by the spring setting. All this is reflected in the pressure switch diagram, which, although a little more complicated than those presented earlier, is not so difficult to read.
The hydraulic line is connected to the filled triangle. A changeover contact and an adjustable spring are also present in the diagram.
Combining elements
Quite often, in hydraulics, one block or apparatus contains several simple elements, such as a valve and a throttle, for ease of understanding, on the hydraulic diagram, the elements included in one apparatus are outlined with a dash-dotted line.
In order to correctly read the hydraulic diagram, you need to know the symbols of the elements, understand the principles of operation and the purpose of hydraulic equipment, be able to gradually delve into the features of individual sections, and correctly combine them into a single hydraulic system.
For the correct design of the hydraulic circuit, you need to draw up a list of elements in accordance with the standard.Shown below hydraulic drive diagram, allowing you to move the rod of the hydraulic cylinder, with the possibility of charging the accumulator.
