When the cylinder is fully extended, pressure continues to build. The flow from the high volume pump is diverted to the tank. This valve has been set at 500 psi. Flow out of the A port is blocked by the upper check valve, so it flows through the directional control valve to the tank. A number of these in the same circuit will represent a common reservoir. They are not dependent on any specific language, being international in scope and character. The center position in a three-position directional control valve is designed according to the type of circuit or application. 
Such a circuit would be used to achieve high speed or rapid advance at low pressure, followed by slow speed and high force. This would be the graphic symbol for a needle valve. An arrow drawn sloping through the arcs indicate that the orifice is adjustable. This would symbolize a fixed orifice. The above level return line terminates at or slightly below the upright legs of the tank symbol. When we add an arrow to the flow line inside a control box, we have indicated that the valve is pressure compensated or true flow control. Now, pump flow is once again directed to the rod side of the actuator to retract the cylinder, and the cycle begins once again. Your QuickPrint Catalogue is generated on demand based on your product selection. A dotted line leaving the circle indicates a drain line to the tank. Inside arrows pointing in indicate the introduction of heat or a heater. Please enable cookies on your browser and try again. Now, lets watch the system work again and see how each component operates. This sends pilot pressure to the lower side of the directional control valve shifting it back into the upper position. A dotted line across opposite corners indicates that it is a filter or a strainer. A dashed line indicates a pilot, drain, purge, or bleed line. The check valve is used to lock and hold the load on the cylinder when the directional control valve is centered. The counterbalance valve has to be set slightly above the load induced pressure. Pilot pressure opposes spring force. Your email address will not be published. When the system pressure is less than the unloading valve setting, flow from the high volume pump flows through the check valve to combine with the flow from the low volume pump. The spring located perpendicular to the arrow indicates that the spring force holds the valve closed. Flow in the port will apply pressure to the piston and extend the cylinder. Pilot to open is indicated with a pilot line directed to the triangle shown to push the circle away from the seal. www.powermotiontech.com is using a security service for protection against online attacks. Lines joining may use a dot at the junction or can be at right angles. When the system pressure reaches 500 psi, this valve will open and allow the flow from the high volume pump to go back to the tank at minimal pressure. When the directional control valve is shifted, the pump goes on stroke, providing flow for the circuit. Next is the pressure compensated pump. This valve, when centered, will block flow from the pump so that pressure will build and de stroke the pump. The springs on both sides of the symbol indicate that the valve is centered when not activated. Now we will examine more closely the components that make up this system. Lines crossing may use loops at crossovers or be straight across. Hydraulic motor graphic symbols are opposite of hydraulic pumps, the difference being that the energy triangle points into the circle, indicating fluid energy entering. Pilot pressure on the upper side of the directional control valve will shift the valve downward. Arrows pointing out indicate heat dissipating or a cooler. A good example of a high-low system would be a press where the ram would rapidly advance up to the work piece. These pumps have a common inlet and separate outlets. It opens and sends pilot pressure to the directional control valve. This circuit usually runs continually to keep the hydraulic fluid clean and cool. The cylinder would retract at a rapid speed. This is indicated by the dotted line running from the primary port perpendicular to the arrow opposite the spring. Next, we will look at directional control valve. As with pumps, many hydraulic motor designs have internal leakage. Pressurized reservoirs are shown as capsules. Notice that in the normal position, the arrow is not aligned with the port. After the unloading valve opens, this check valve closes, so that the flow from the low volume pump wont flow to the unloading valve. Pilot pressure opens the sequence valve on the bottom. The directional control valve directs flow to the lines in the upper circuit. It is blocked at the check valve and blocked at the closed sequence valve, but flow to the B port of the actuator is open. Reservoirs that are vented are shown as a rectangle with the top line omitted. The pressure compensated pump de-strokes when the directional control valve is centered. Symbols are critical for technical communication. Figure 12.14 is a high-low circuit. The below level return line touches the bottom of the tank symbol. The closed sequence valve blocks another, but flow to the A port of the actuator is open. They are normally closed valves that open at a predetermined setting. As the cylinder rod retracts, flow from the B port is blocked at the check valve, so it exits to the tank through the directional control valve. Flow through the valve is from the primary to the secondary port. Although initially most circuits may appear complicated, recognizing standard symbols and systematic flow tracings simplifies the process. A simplified symbol to represent the reservoir minimizes the need to draw a number of lines returning to the reservoir. As the circle moves into the triangle, the flow is blocked or checked. Here, flow can go three places. The service requires full JavaScript support in order to view this website. By tracing the flow in the circuit, one should be able to determine how the circuit is designed to operate. First, we will look at the off-line or kidney loop filter circuit. The service requires full cookie support in order to view this website. Correct schematic reading is the most important element of hydraulic troubleshooting. This is a double pump. This is a tandem center. Please enable JavaScript on your browser and try again. In position one, or centered, fluid flows from the pump through the valve to the tank. Finally, we will look at the systems pressure relief valve. This circuit consists of a pump motor group, a filter, and an air-tofluid heat exchanger. This centered position indicates the flow path of the fluid while the valve is centered. These symbols have the same function as the ground symbol in electric circuits. These symbols can be rather simple to draw, if the logic and elementary forms used in symbol design are understood. Continuous lines indicate a working line, pilot supply, return, or electrical line. The symbol for a directional control valve has multiple envelopes showing the number of positions the valve may have. This in turn increases the backpressure, causing the counterbalance valve to open, allowing the cylinder to lower the load at a controlled rate. An arrow diagonally through the spring indicates that the spring force is adjustable. Check valves may be piloted to open or to close. The graphic symbol for a hydraulic fluid conditioner device is shown with a square standing on end. Now, we will take a look at the high-low pump group. Follow the flow past the relief valve to the directional control valve, which is shifted to the upper position, as shown. The symbol for a flow control valve begins with an upper and lower arc. Finally, we will look at the counterbalance valve. A schematic is a compilation of interconnected graphic symbols, showing a sequence of operational flow. Two energy triangles pointing in indicate a bi-directional or reversible motor. An internal rectangle adjacent to the symbol for the piston indicates a cushion device at the end of the stroke. Copyright 2002-2022 Sun Hydraulics LLC, a, Hydrostatic Transmission Flushing Circuit, Gauge Port Snubbers / Adaptors / Line Fuses, Proportional priority bypass flow divider assembly, Solenoid-controlled priority bypass flow divider assembly, Fixed orifice, bypass/restrictive, priority flow control with relief assembly, Proportional bypass flow divider assembly, Pressure compensated priority flow control assembly, Bypass/restrictive, priority flow control with reverse flow check assembly. Both work ports are routed back to the tank, so there is no pressure in the work port lines, except between the rod end of the cylinder and the counterbalance valve. 15, the cylinder has a weight that would cause it to free fall or drop at an uncontrolled rate. Now that the circuit is understood, proper function of the system will depend on the proper setting and function of the sequence valves and the proper function of the hydraulically piloted directional control valve. The Electronic Technician's Diary - Berbagi Ilmu dan Belajar. The pressure will continue to rise until it reaches the relief valve setting. When shifted, the directional control valve applies pressure on the cylinder piston. The circuit in Figure 12.13 uses two sequence valves.
Pilot to close is indicated by directing the pilot line to the back of the circle or into the seat. A counterbalance valve is placed in the rod end port of the cylinder to apply backpressure. This indicates that the valve is normally closed. When the valve is shifted to position two, fluid flows from P to A, extending the cylinder. Arrows both pointing in and out would indicate a temperature controller or temperature that is maintained between two predetermined limits. The pump draws hydraulic fluid from the reservoir, passing the fluid through a filter and an air-to-fluid heat exchanger. When the directional control valve is reversed, the pressure drops and the unloading valve closes. When the hydraulic pressure piloted from the primary port exceeds the force of the spring, the valve moves to the open position, aligning the primary and secondary ports. If the diameter of the rod is larger than usual for the bore size, the symbol must reflect this. Basic Hydraulics - Understanding Schematics, Wednesday, September 23, 2020 at 4:37:00 AM PDT, Wednesday, September 23, 2020 at 7:27:00 AM PDT, Fault Codes CUMMINS ISB ISC ISL ISBe ISDe and QSB3.3 CM2150, Fault Codes CUMMINS GTA38 K38 K50 QSK38 QSK50/60 CM850, Fault Codes CUMMINS Signature ISX QSX15 CM570, Fault Codes CUMMINS ISB ISBe QSB4.5 QSB5.9 QSB6.7 ISC QSC8.3 ISL ISLe QSL9 CM850 (CM2850), Figure 12.1 - schematic symbols are drawn withsimple shapes such as these, Figure 12.2 - representation of schematic linesthat would be found in a hydraulic schematic, Figure 12.3 - schematic representations ofhydraulic reservoirs, Figure 12.4 - schematic representations of hydraulic pumps, Figure 12.5 - schematic illustrations of hydraulicflow control valves, Figure 12.6 - schematic illustrations of directional control valves, Figure 12.7 - schematic illustrations of pressure valves, Figure 12.8 - schematic illustrations ofcheck valves, Figure 12.9 - schematic illustrations ofhydraulic motors, Figure 12.10 - schematic illustrations of cylinders, Figure 12.11 - schematic illustrations of hydraulic filters, Figure 12.13 - a hydraulic schematic for circuit #1, Figure 12.14 - a high-low circuit schematic diagram for circuit #2, Figure 12.15 - schematic illustration of circuit #3. Now we will examine more closely the components that make up this system. Fluid power cylinders with no unusual relationship between the bore and rod size are shown in Figure 12.10: single acting, double acting, and double rod. A flow control valve with a check valve indicates reverse flow around the valve. During low-pressure rapid advance, both pump flows are combined. At that time, the pressure starts to build. Flexible or curved lines indicate a hose, usually connected to a moving part. Understanding graphic line symbols is critical to proper interpretation of schematics. This process is called reading a schematic. The elementary forms of symbols are circles, squares, triangles, arcs, arrows, dots, and crosses. The symbol for a pressure valve begins with a single envelope. Free flow is opposite the direction the triangle is pointed. Reservoirs may have fluid lines terminating above or below the fluid level. www.powermotiontech.com is using a security service for protection against online attacks. You will be redirected once the validation is complete. Adding a check valve across and parallel to the ports indicate that the filter has a bypass. First, the unloading valve. Tracing the flow in this circuit reveals that it is designed to keep retracting and extending automatically. Check valve symbols are drawn with a small circle inside an open triangle. This valve limits the maximum system pressure. To shift the valve or activate it, devices such as a mechanical handle or lever, an electric solenoid, or hydraulic pilot pressure are used. Hydraulic graphic symbols emphasize the function and methods of operation of the components. The counterbalance valve maintains backpressure on the rod side of the cylinder so that the cylinder brings the load down at a controlled rate of speed. At this time, there is pressure being maintained between the pump and directional control valve, but no flow. As with a filter, the base symbol is shown as a square on end. While there are many types of center configurations, the four most common are tandem, closed, float, and open. The backpressure is the result of the load trying to force the fluid out of the cylinder and through the counterbalance valve, which is closed.
Their graphic symbols are often confused. Pump flow is now directed to the lower circuit and the flow here goes to three places. In short, they explain how a circuit functions. When the unloading valve opens, the large pumps flow returns to the tank and the small pumps flow is used to do the work. All pressure valves are normally closed with the exception of a pressure reducing valve, which is normally open. www.powermotiontech.com is using a security service for protection against online attacks. When the cylinder is fully retracted, pressure will build in the pilot passage of the sequence valve. The upper check valve blocks one passage. This is a three-position, four-way valve with a float center. Enter your email address below to receive a link to the pdf file. A three-position directional control valve is shown with three envelopes. Shifting to position three allows flow from P to B and from A to T, retracting the cylinder. Next, we will look at the function of the check valve. The low volume pump would produce the little flow needed to continue moving the ram into the work piece. Process time depends on the models selected and the resulting file size. In Figure 12. This process is automatic. Privacy Policy, Electro-Pneumatic Regulator & Flow Controller Design.
Such a circuit would be used to achieve high speed or rapid advance at low pressure, followed by slow speed and high force. This would be the graphic symbol for a needle valve. An arrow drawn sloping through the arcs indicate that the orifice is adjustable. This would symbolize a fixed orifice. The above level return line terminates at or slightly below the upright legs of the tank symbol. When we add an arrow to the flow line inside a control box, we have indicated that the valve is pressure compensated or true flow control. Now, pump flow is once again directed to the rod side of the actuator to retract the cylinder, and the cycle begins once again. Your QuickPrint Catalogue is generated on demand based on your product selection. A dotted line leaving the circle indicates a drain line to the tank. Inside arrows pointing in indicate the introduction of heat or a heater. Please enable cookies on your browser and try again. Now, lets watch the system work again and see how each component operates. This sends pilot pressure to the lower side of the directional control valve shifting it back into the upper position. A dotted line across opposite corners indicates that it is a filter or a strainer. A dashed line indicates a pilot, drain, purge, or bleed line. The check valve is used to lock and hold the load on the cylinder when the directional control valve is centered. The counterbalance valve has to be set slightly above the load induced pressure. Pilot pressure opposes spring force. Your email address will not be published. When the system pressure is less than the unloading valve setting, flow from the high volume pump flows through the check valve to combine with the flow from the low volume pump. The spring located perpendicular to the arrow indicates that the spring force holds the valve closed. Flow in the port will apply pressure to the piston and extend the cylinder. Pilot to open is indicated with a pilot line directed to the triangle shown to push the circle away from the seal. www.powermotiontech.com is using a security service for protection against online attacks. Lines joining may use a dot at the junction or can be at right angles. When the system pressure reaches 500 psi, this valve will open and allow the flow from the high volume pump to go back to the tank at minimal pressure. When the directional control valve is shifted, the pump goes on stroke, providing flow for the circuit. Next is the pressure compensated pump. This valve, when centered, will block flow from the pump so that pressure will build and de stroke the pump. The springs on both sides of the symbol indicate that the valve is centered when not activated. Now we will examine more closely the components that make up this system. Lines crossing may use loops at crossovers or be straight across. Hydraulic motor graphic symbols are opposite of hydraulic pumps, the difference being that the energy triangle points into the circle, indicating fluid energy entering. Pilot pressure on the upper side of the directional control valve will shift the valve downward. Arrows pointing out indicate heat dissipating or a cooler. A good example of a high-low system would be a press where the ram would rapidly advance up to the work piece. These pumps have a common inlet and separate outlets. It opens and sends pilot pressure to the directional control valve. This circuit usually runs continually to keep the hydraulic fluid clean and cool. The cylinder would retract at a rapid speed. This is indicated by the dotted line running from the primary port perpendicular to the arrow opposite the spring. Next, we will look at directional control valve. As with pumps, many hydraulic motor designs have internal leakage. Pressurized reservoirs are shown as capsules. Notice that in the normal position, the arrow is not aligned with the port. After the unloading valve opens, this check valve closes, so that the flow from the low volume pump wont flow to the unloading valve. Pilot pressure opens the sequence valve on the bottom. The directional control valve directs flow to the lines in the upper circuit. It is blocked at the check valve and blocked at the closed sequence valve, but flow to the B port of the actuator is open. Reservoirs that are vented are shown as a rectangle with the top line omitted. The pressure compensated pump de-strokes when the directional control valve is centered. Symbols are critical for technical communication. Figure 12.14 is a high-low circuit. The below level return line touches the bottom of the tank symbol. The closed sequence valve blocks another, but flow to the A port of the actuator is open. They are normally closed valves that open at a predetermined setting. As the cylinder rod retracts, flow from the B port is blocked at the check valve, so it exits to the tank through the directional control valve. Flow through the valve is from the primary to the secondary port. Although initially most circuits may appear complicated, recognizing standard symbols and systematic flow tracings simplifies the process. A simplified symbol to represent the reservoir minimizes the need to draw a number of lines returning to the reservoir. As the circle moves into the triangle, the flow is blocked or checked. Here, flow can go three places. The service requires full JavaScript support in order to view this website. By tracing the flow in the circuit, one should be able to determine how the circuit is designed to operate. First, we will look at the off-line or kidney loop filter circuit. The service requires full cookie support in order to view this website. Correct schematic reading is the most important element of hydraulic troubleshooting. This is a double pump. This is a tandem center. Please enable JavaScript on your browser and try again. In position one, or centered, fluid flows from the pump through the valve to the tank. Finally, we will look at the systems pressure relief valve. This circuit consists of a pump motor group, a filter, and an air-tofluid heat exchanger. This centered position indicates the flow path of the fluid while the valve is centered. These symbols have the same function as the ground symbol in electric circuits. These symbols can be rather simple to draw, if the logic and elementary forms used in symbol design are understood. Continuous lines indicate a working line, pilot supply, return, or electrical line. The symbol for a directional control valve has multiple envelopes showing the number of positions the valve may have. This in turn increases the backpressure, causing the counterbalance valve to open, allowing the cylinder to lower the load at a controlled rate. An arrow diagonally through the spring indicates that the spring force is adjustable. Check valves may be piloted to open or to close. The graphic symbol for a hydraulic fluid conditioner device is shown with a square standing on end. Now, we will take a look at the high-low pump group. Follow the flow past the relief valve to the directional control valve, which is shifted to the upper position, as shown. The symbol for a flow control valve begins with an upper and lower arc. Finally, we will look at the counterbalance valve. A schematic is a compilation of interconnected graphic symbols, showing a sequence of operational flow. Two energy triangles pointing in indicate a bi-directional or reversible motor. An internal rectangle adjacent to the symbol for the piston indicates a cushion device at the end of the stroke. Copyright 2002-2022 Sun Hydraulics LLC, a, Hydrostatic Transmission Flushing Circuit, Gauge Port Snubbers / Adaptors / Line Fuses, Proportional priority bypass flow divider assembly, Solenoid-controlled priority bypass flow divider assembly, Fixed orifice, bypass/restrictive, priority flow control with relief assembly, Proportional bypass flow divider assembly, Pressure compensated priority flow control assembly, Bypass/restrictive, priority flow control with reverse flow check assembly. Both work ports are routed back to the tank, so there is no pressure in the work port lines, except between the rod end of the cylinder and the counterbalance valve. 15, the cylinder has a weight that would cause it to free fall or drop at an uncontrolled rate. Now that the circuit is understood, proper function of the system will depend on the proper setting and function of the sequence valves and the proper function of the hydraulically piloted directional control valve. The Electronic Technician's Diary - Berbagi Ilmu dan Belajar. The pressure will continue to rise until it reaches the relief valve setting. When shifted, the directional control valve applies pressure on the cylinder piston. The circuit in Figure 12.13 uses two sequence valves.
Pilot to close is indicated by directing the pilot line to the back of the circle or into the seat. A counterbalance valve is placed in the rod end port of the cylinder to apply backpressure. This indicates that the valve is normally closed. When the valve is shifted to position two, fluid flows from P to A, extending the cylinder. Arrows both pointing in and out would indicate a temperature controller or temperature that is maintained between two predetermined limits. The pump draws hydraulic fluid from the reservoir, passing the fluid through a filter and an air-to-fluid heat exchanger. When the directional control valve is reversed, the pressure drops and the unloading valve closes. When the hydraulic pressure piloted from the primary port exceeds the force of the spring, the valve moves to the open position, aligning the primary and secondary ports. If the diameter of the rod is larger than usual for the bore size, the symbol must reflect this. Basic Hydraulics - Understanding Schematics, Wednesday, September 23, 2020 at 4:37:00 AM PDT, Wednesday, September 23, 2020 at 7:27:00 AM PDT, Fault Codes CUMMINS ISB ISC ISL ISBe ISDe and QSB3.3 CM2150, Fault Codes CUMMINS GTA38 K38 K50 QSK38 QSK50/60 CM850, Fault Codes CUMMINS Signature ISX QSX15 CM570, Fault Codes CUMMINS ISB ISBe QSB4.5 QSB5.9 QSB6.7 ISC QSC8.3 ISL ISLe QSL9 CM850 (CM2850), Figure 12.1 - schematic symbols are drawn withsimple shapes such as these, Figure 12.2 - representation of schematic linesthat would be found in a hydraulic schematic, Figure 12.3 - schematic representations ofhydraulic reservoirs, Figure 12.4 - schematic representations of hydraulic pumps, Figure 12.5 - schematic illustrations of hydraulicflow control valves, Figure 12.6 - schematic illustrations of directional control valves, Figure 12.7 - schematic illustrations of pressure valves, Figure 12.8 - schematic illustrations ofcheck valves, Figure 12.9 - schematic illustrations ofhydraulic motors, Figure 12.10 - schematic illustrations of cylinders, Figure 12.11 - schematic illustrations of hydraulic filters, Figure 12.13 - a hydraulic schematic for circuit #1, Figure 12.14 - a high-low circuit schematic diagram for circuit #2, Figure 12.15 - schematic illustration of circuit #3. Now we will examine more closely the components that make up this system. Fluid power cylinders with no unusual relationship between the bore and rod size are shown in Figure 12.10: single acting, double acting, and double rod. A flow control valve with a check valve indicates reverse flow around the valve. During low-pressure rapid advance, both pump flows are combined. At that time, the pressure starts to build. Flexible or curved lines indicate a hose, usually connected to a moving part. Understanding graphic line symbols is critical to proper interpretation of schematics. This process is called reading a schematic. The elementary forms of symbols are circles, squares, triangles, arcs, arrows, dots, and crosses. The symbol for a pressure valve begins with a single envelope. Free flow is opposite the direction the triangle is pointed. Reservoirs may have fluid lines terminating above or below the fluid level. www.powermotiontech.com is using a security service for protection against online attacks. You will be redirected once the validation is complete. Adding a check valve across and parallel to the ports indicate that the filter has a bypass. First, the unloading valve. Tracing the flow in this circuit reveals that it is designed to keep retracting and extending automatically. Check valve symbols are drawn with a small circle inside an open triangle. This valve limits the maximum system pressure. To shift the valve or activate it, devices such as a mechanical handle or lever, an electric solenoid, or hydraulic pilot pressure are used. Hydraulic graphic symbols emphasize the function and methods of operation of the components. The counterbalance valve maintains backpressure on the rod side of the cylinder so that the cylinder brings the load down at a controlled rate of speed. At this time, there is pressure being maintained between the pump and directional control valve, but no flow. As with a filter, the base symbol is shown as a square on end. While there are many types of center configurations, the four most common are tandem, closed, float, and open. The backpressure is the result of the load trying to force the fluid out of the cylinder and through the counterbalance valve, which is closed.
Their graphic symbols are often confused. Pump flow is now directed to the lower circuit and the flow here goes to three places. In short, they explain how a circuit functions. When the unloading valve opens, the large pumps flow returns to the tank and the small pumps flow is used to do the work. All pressure valves are normally closed with the exception of a pressure reducing valve, which is normally open. www.powermotiontech.com is using a security service for protection against online attacks. When the cylinder is fully retracted, pressure will build in the pilot passage of the sequence valve. The upper check valve blocks one passage. This is a three-position, four-way valve with a float center. Enter your email address below to receive a link to the pdf file. A three-position directional control valve is shown with three envelopes. Shifting to position three allows flow from P to B and from A to T, retracting the cylinder. Next, we will look at the function of the check valve. The low volume pump would produce the little flow needed to continue moving the ram into the work piece. Process time depends on the models selected and the resulting file size. In Figure 12. This process is automatic. Privacy Policy, Electro-Pneumatic Regulator & Flow Controller Design.