Because of reducing valve (B), pressure at CYL1 stays at 350 psi no matter how high system pressure climbs. Once the first actuator has completed its cycle, the sequence valve opens, allowing the second actuator to move. A sequence valve is a pressure-operated, normally closed, poppet or spool valve that opens at an adjustable set pressure. Pressure in the rod end of CYL2 finally increases to 300 psi. Two-cylinder sequence circuit. With a kick-down sequence valve, add the modular pilot-operated check valve shown in the cap-end line of the Clamp cylinder. Kim Fausing, President & CEO of Danfoss A/S, says, “Already today we have a very broad portfolio of solutions, which plays a vital role in combating climate change and air pollution. This circuit has some heat generation but makes sure the Clamp cylinder never goes below a certain pressure while the Work cylinder extends and retracts. With a sequence-valve spring setting of 65 psi, it will not open to tank until pressure after check valve (B)goes at least 65 psi higher than pump compensator setting, as in Figure 20-26. Directional valve DV02, shifted by a limit switch, ensures that the Clamp cylinder contacts the part before the Work cylinder cycles. CYL1 extends until it contacts a part. Relief valve (A), installed anywhere in the pressure line, protects the system when set 150 to 200 psi higher than the pump compensator. At the same time, there is minimal energy loss and heat generation. Figures 20-14 through 20-17 show a circuit using a kick-down sequence valve operating two cylinders. When it is necessary to positively locate an actuator, always use a limit switch or limit valve. They may be used to assure priority hydraulic pressure in one system before another can operate. Pilot line (C) from the pump outlet before check valve (B) goes to the external drain port of sequence valve (A). Figure 1-16 in Chapter 1 shows and explains a circuit using a pressure-compensated pump and a relief valve. Some older circuits have one directional valve and up to six sequence valves. Hydraulic sequence valve is also type of pressure control valve. Another potential problem with a sequence valve circuit is that actuator position cannot be assured. Hydraulic sequence valves will be used when we need to provide the sequence in operation of two or more than two hydraulic cylinder. Figure 20-3 shows the symbol for a kick-down sequence valve. Figures 20-20 through 20-23 show a kick-down sequence valve automatically unloading a pump at the end of a cycle. LunchBox Sessions is a new take on online industrial training, full of interactivity, used by individuals, schools, and companies around the world. Sequence valves often generate a great deal of heat because the first actuator to move takes higher pressure than the subsequent actuators. A pressure drop of more than 50 psi across a kick-down sequence valve keeps it full open. The check valve prevents the signal being trapped and allows it to decay back past the sequence valve poppet. Figures 20-12 through 20-15 show a modular or sandwich-type sequence valve in a circuit. A pilot-operated check valve blocks pressurized fluid in the cap end of the clamp cylinder when the kick-down sequence valve opens. Direct-acting sequence valves are employed in low flow applications such as providing signals to operate directional control valves or to positively release a brake before a machine can function. Figure 20-2 pictures the symbol for an externally piloted sequence valve. Pressure Dependent Valves The following Pressure Dependent Controls are often used in Pneumatic applications • Pressure Sequence Valve • Pressure Relief Valve • Pressure Regulator Pressure Sequence Valves Figure 6.1 Pressure Control Volves • Pressure Sequence valve is essentially a switch on or off valve • Sequence Valve generates a pneumatic signal if the sensing … The pump, unloading through kick-down sequence valve (A) at about 50 psi, is ready for a cycle. The sequencing pressure is set via the adjustment type (4). Pressure sequence valve is used to assure priority hydraulic pressure in one system before another can operate. Additionally, the outlet pressure should also be cycled on and off to ensure the pressure regulator returns to the desired set point. Without a relief valve in the circuit, pressure might easily exceed the rating of the valves, piping, pump, and cylinder. The sequence valve is used to ensure that a certain pressure level is achieved in one branch of the circuit before a second branch is activated. Version “P” The compression spring (3) holds the control spool (2) in initial position, the valve is blocked. Figure 20-12 pictures the system at rest. The schematic drawing notes the valve pressure settings. Pressure sequence valve is used to assure priority hydraulic pressure in one system before another can operate. CYL2 retracts first because it only takes 100 psi to move it, while the pressure setting at sequence valve (D) is 300 psi. When CYL1 makes part contact, Figure 20-6, system pressure increases rapidly. When the component is undamped, the pressure falls and the sequence valve closes. In some circuits the pilot signal to open the valve is from a source other than the line feeding it. They are the safeguards that limit maximum pressure in a system by diverting e… This pressure drop results in heat, because its energy does not do useful work. The primary circuit never drops below the sequence valve setting as long as the primary pressure is equal to or greater than the sequence pressure setting. Pressure at CYL2 changes as it retracts, but never goes higher than 200 to 250 psi. Operation: The VektorFlo ® sequence valve operates as a pressure sensitive, normally closed element in a clamping system. a. sequence valves are used to perform number of operations one after the other after the set pressure is reached b. sequence valves are used to perform number of operations continuously before the set pressure is reached c. sequence valves after reaching set pressure oil is flown to the tank d. all of the above A sequence valve is a pressure-operated, normally closed, poppet or spool valve that opens at an adjustable set pressure. The proportional pressure sequence valve EPDZA allows oil coming from channel P to flow from a defined, proportionally adjustable opening pressure to channel A. This sequence-valve relief works anywhere in the circuit to protect any line from overpressure. Adding check valve (B) at the pump outlet assures that pressure at the pump never goes above the compensator setting. The modular sequence valve under DV02 assures that the Clamp cylinder sees at least 700 psi before the Work cylinder extends. Sometime we feel need,for various mechanism and operation of machines, of operation of hydraulic cylinders in a sequence. When pressure on CYL2 is less than 500 psi, the pressure drop across sequence valve (E)generates heat. An important feature of all pressure sequence valves is a separate drain connection from the spring chamber. When CYL2 bottoms out, as in Figure 20-8, pressure at gauges PG1 and PG5 goes to 750 psi and the system relief valve starts dumping fluid to tank. It is applied for pressure-dependent connection of a second system. After the Work cylinder retracts fully, deenergize solenoid A1 and energize solenoid B1 on the directional valve, retracting the Clamp cylinder to its home position. The Clamp cylinder returns, DV01 deenergizes, and the cycle ends. Type DZ pilot-operated sequence valve is used for sequence acting with pressure controlling in hydraulic system.Type DZ valve is combined a pilot valve, main valve with insert spool and a check valve whick can be elective.According to circumstances for controlling oil of supply and drain, be composed different type( See symbol of diagram ). In this condition, the input pressure necessary to hold the valve fully open has only to overcome the resistance caused by the secondary circuit pressure and the light spring situated behind the main spool. Even if CYL2 required only 25 psi to move, sequence valve E keeps fluid from it. A sequence valve is somewhat similar to a relief valve except that, after the set pressure has been reached, the sequence valve diverts the fluid to a second actuator or motor to do work in another part of the system. A reducing valve drain can usually be combined with the drains from other reducing valves or sequence valves but should never be teed into a main tank return line. They may be used to assure priority hydraulic pressure in one system before another can operate. (Valve (A) has a low-pressure spring rate between 50 and 250 psi.) PRESSURE SEQUENCE VALVES. © 2021 Endeavor Business Media, LLC. In Figure 20-5, solenoid A1 is energized and CYL1 is extending. (Note that a kick-down sequence valve causes less heat generation, but does not hold pressure on the primary circuit.). According to the different functions, it can be called sequence valve, back pressure valve, … Figure 20-1 shows the schematic symbol for an internally piloted sequence valve. This means there is usually a high pressure drop across a sequence valve that results in wasted energy. Should it be internally drained, any pressure in the output port will be reflected back into the spring chamber causing a malfunction. A kick-down sequence valve keeps unloading the pump until pressure drop across it falls below 50 psi. The pump never relieves to tank and the circuit always relieves when pressure in it increases more than the sequence-valve spring setting. With this type of sequencing circuit, the first cylinder may lose holding power when the second directional valve shifts. The pressure drop allows kick-down sequence valve (A) to close (or reset) for the retract cycle. Said pilot controlled sequence valve is used in an hydraulic apparatus for checking a connection between a source of pressure medium and an accumulator. In this circuit, CYL2 retracts first, while CYL1 holds under pressure when the directional valve shifts. Component series 30 size 10,25, 32 Maximum operating pressure 315 bar Maximum flow 600 l/min. A separate directional valve for each cylinder is one way to sequence such a circuit. If decreasing pressure is a problem, tee a small accumulator in the line between pilot-operated check valve (C) and the cylinder. When it is only necessary to know that pressure has built, a sequence valve in the line keeps fluid from the next action until the limit switch is contacted and pressure increases. This circuit simplifies the electrical controls because it only uses one solenoid. Trapped fluid modifies set pressure at best or keeps the valve from opening at worst. An important feature of all pressure sequence valves is a separate drain connection from the spring chamber. An important feature of all pressure sequence valves is … When an outside force starts pushing back against the cylinder, pressure in its cap end increases. With a short cycle time, pressure drop is minimal. Reducing valve (B) prevents CYL1 from crushing the part while CYL2 does its work. (Pressure at CYL1 may drop due to leaks at seals or piping with the circuit described here.) The cylinder retracts at the pressure required to move it, Figure 20-22. Because this takes low pressure and all pump flow, there is no heat generation. Pressure at the rod end of CYL1 is whatever it takes to stroke the cylinder home. Mit Flexionstabellen der verschiedenen Fälle und Zeiten Aussprache und … Figure 6-15 shows an installation of two sequence valves that control the sequence of operation of three actuating cylinders. Any other time the sequence valve stays closed because its inlet never sees pressure higher than compensator setting. See a leakage make-up circuit using an accumulator in Chapter 1, Figures 1-24 to 1-27. In some ways, a sequence valve is a directional valve, allowing flow to occur. Energizing solenoid B1 on directional valve (A) , Figure 20-9, starts returning the cylinders to their at-rest positions. Relief valves make it possible to avoid this hazard. With the circuit at rest and the pump running, system pressure is the pump compensator setting. After the Clamp cylinder returns, DV01 deenergizes and the cycle ends. Without controlling these forces, the power components and expensive equipment could get damaged. A good feature of a sequence circuit: if cylinder 1 is a clamp, it does not matter how thick the part is. Pressure build up could be from a damaged or stalled cylinder or a kinked line. With a short cycle time, pressure drop is minimal. A limit switch then deenergizes solenoid A1 on directional valve (B) . Sequence valves produce heat in a hydraulic system. Repeat the pressure setting sequence if the outlet pressure does not return to the desired setting. This allows full pressure to appear on both cylinders when they stall, instead of the pressure having to divide between them. After the work is contacted, Figure 20-18, energize solenoid A2 on directional valve DV02. Pump flow goes to the Clamp cylinder, extending it to the work. Figures 1-17 to 1-19 show another circuit using an accumulator to protect the pump. When pressure reaches 300 psi in Figure 20-11, CYL1 starts to retract. Chapter 10 covering flow controls, explains the reasons for this. Its operation is different from a normal sequence valve. See a leakage make up circuit using an accumulator in Chapter 1, Figures 1-24 to 1-27. If the pressure in channel P drops under the setpoint value, the valve closes with low hysteresis. Kick-down sequence valve (A) stays closed because its setting is higher than the pressure retracting the cylinder. The modular kick-down sequence valve under DV02 causes 700-psi pressure to build in the Clamp cylinder before the Work cylinder extends. The accumulator circuit almost eliminates pressure spikes — plus it gives faster actuator response at the start of a cycle. In general, this kind of valve is often used. Figures 20-25 through 20-27 show an overpressure protection circuit that is less prone to problems. When fluid first enters the system at low pressure, the valve is closed, blocking the flow of fluid to devices down stream. When oil passes through sequence valve (D) , it first sends a pilot signal to open pilot-operated check valve (C) . A pilot-operated check valve, added to the inlet of the first cylinder, maintains pressure on the first cylinder while the second cylinder strokes at low pressure. Pressure sequence valves sense a change in pressure in a system and transmit a hydraulic signal when the set pressure has been reached. When pressures at port 1 and port 2 both exceed the setting of the valve, the valve goes “full open”, or “sequences”. Some designers use a relief valve with a pressure-compensated pump to reduce pressure spikes as the pump rapidly goes from full flow to no flow. Most pneumatic and hydraulic power systems are designed to operate within a defined pressure range. (See further explanation in conjunction with Figures 20-23.). Upon reaching set pressure, the valve opens enough to let excess pump flow pass on to the second operation. The extra cost of special manifolds for this arrangement is a good investment. Sequence valves may be internally pilot-operated as in Figure 20-1.This is the standard arrangement for the pilot source. DZ-30 Pressure hydraulic sequence valve, pilot-operated. The flow to cylinder B is through sequence valve S1 which will open when the pressure at the full bore end of cylinder A has attained a certain value, probably owing to it having been stopped by some external object or a: the extremity of its stroke. Lernen Sie die Übersetzung für 'pressure sequence valve' in LEOs Englisch ⇔ Deutsch Wörterbuch. Pump pressure at the internal pilot is trying to open sequence valve (A), but at the same time holding it closed through the external drain port. In Figure 4 when the directional control valve is switched to the 'tramline' condition, cylinder A will extend followed by cylinder B. The valve is normally closed until the pressure setting of the control section is reached, when the main spool opens fully with very little resistance to flow. The main reason this overpressure relieving circuit is better than a circuit with a standard relief valve is that adjusting the pump compensator not only changes system pressure, but also automatically raises relief pressure. Cylinder 2 will not extend until cylinder 1 securely clamps any thickness part. Sequence circuits are unreliable and difficult to set up and maintain. This is because, unlike a conventional relief valve, a high pressure can occur in the output port during the normal course of operation. The circuit has returned to the conditions of Figure 20-20. As pressure passes through 300 psi (as seen on gauges PG1, 2, and 3), CYL2 is still stationary. With this acquisition, our third within electrification, we have added a well-established North American presence within electrification, which nicely complements our global footprint.”, Sign up for Hydraulics & Pneumatics eNewsletters. Hydraulic Manifolds . If decreasing pressure is a problem, tee a small accumulator in the line between the manifold and the cylinder's cap-end line. A sequence valve is a pressure valve designed to open when its set pressure is reached, providing a path of flow alternate and sequential to the primary circuit. Two-stage sequence valves suitable for high flow rates are available and one specialized form known as a 'Circuit Breaker' or 'Kickdown' sequence valve is Figure 2. A kick-down sequence valve is a unique component that can simplify the electrical control of systems with one or two cylinders. Most sequence circuits require a heat exchanger, especially when they cycle rapidly. The Clamp cylinder maintains force because the modular pilot-operated check traps 700-psi fluid in it. With this overpressure circuit there is no protection from pressure spikes when the pump compensator has to work quickly. A normally closed sequence valve with integral reverse-flow check valve is shown in   Figure 1 together with an established application which is to sense that a component has been clamped before initiating the next stage in a "sequence" of operations. Oil from the rod end of the cylinder flows freely to tank, greatly reducing pressure in this line. This sends pump flow to the rod end of the Workcylinder. When the cylinder that must move first has the highest resistance, a single directional control will not work. The cylinder extends until it meets the part. To retract the Work cylinder, deenergize solenoid A2 as in Figure 20-19. When the primary hydraulic circuit reaches a preset pressure, flow is permitted to the secondary circuit. To retract the Work cylinder, deenergize solenoid A2 as in Figure 20-15. Figure 20-11. In fact a sequence valve may be used as a relief valve in any circuit here excessive back pressures are encountered in the return line. When pressure reaches the setting of kick-down sequence valve (A) , the valve opens and unloads the pump to tank at approximately 50 psi. This allows full pressure to appear on both cylinders when they stall, instead of the pressure having to divide between them. This is because, unlike a conventional relief valve, a high pressure can occur in the output port during the normal course of operation. All rights reserved. When using flow controls with sequence circuits, meter-in flow control is the only workable option. Gauges are placed to show working pressures as the sequence progresses. When pressure reaches 500 psi, as shown in Figure 20-7, sequence valve Eopens enough to let excess pump fluid flow to CYL2. Another use for a kick-down sequence is unloading a pump after the circuit reaches maximum pressure. You can also choose from 1 year, 6 months, and 1.5 years pressure sequence valve, as well as from metal check valves, ball valves pressure sequence valve, and whether pressure sequence valve is … The acquisition brings complementary technology to Danfoss’s current product range, with inverter and motor drives rated to 6 MW for application in marine, off- and on-highway, and oil and gas industries. If the Work cylinder only requires 450 psi to extend, the 300-psi energy loss generates heat. Energizing solenoid A1 on directional valve (B), Figure 20-21, directs oil to the cap end of the punch cylinder. When CYL2 fully retracts, system pressure increases rapidly, as seen in Figure 20-10. Hydraulic Hoses. On the other hand, if the clamp cylinder locks up for any reason before contacting the part, pressure will build and allow cylinder 2 to cycle. CAUTION: When using any pressure-control valve, the only thing certain when they operate is that they have reached set pressure. A fixed-displacement pump, unloading at no pressure through a tandem-center valve, is the power source. When pressure on CYL2goes higher than 500 psi, there is no energy loss, hence no heat. A punch cylinder application, using a single-solenoid, two-position, spring-return valve and a fixed-displacement pump could operate this way with little heat generation. Fluid at the inlet port of the valve cannot pass to the secondary circuit or outlet port, until reaching set pressure. The outlet of sequence valve (A) goes directly to tank. The main difference is that a sequence valve always has an external drain line — and often has a bypass check valve for reverse flow. Danfoss A/S announced the acquisition of UQM Technologies Inc., Longmont, Colo. Danfoss A/S announced the acquisition of UQM Technologies Inc., Longmont, Colo., a developer and manufacturer of power-dense, high-efficiency electric motors, generators, power electronic controllers and fuel cell compressors for the commercial truck, bus, automotive, marine, and industrial markets. However, relief valve (D) may cause problems, as stated in Chapter 1, page ACC7. Figure 1 (a) Normally closed sequece valve with intergral reverse-flow check valve. Pressure in the rest of the circuit continues to climb until it reaches 500 psi. Hydraulic sequence valves will be used when we need to provide the sequence in operation of two or more than two hydraulic cylinder. It remains open even when the secondary circuit pressure is less than the valve set pressure only resetting at a very low value. Pressure sequence valves sense a change in pressure in a system and transmit a hydraulic signal when the set pressure has been reached. Pressure builds until the punch goes through the part. It remains open even if conditions in the downstream circuit cause the circuit pressure to fall below the control setting. Some designs use a spring acting directly on the spool or poppet, others are pilot-operated. Hydraulic Cylinders. Pressure valves with a switching task are referred to as pressure valves with fixed throttle: sequence valves and unloading valves. Where the output flow is used to drive cylinders directly, two-stage valves are usually more appropriate. ANSWER: it is a combination of adjustable pressure relief valve and directional control valve Pressure continues to climb at CYL1 until it reaches 350 psi. When pressure is 350 psi at CYL1, reducing valve (B) shuts and holds. If the actuator with the least resistance is first in the sequence, the circuit runs smoothly without other valving. Energizing one solenoid extends the first cylinder. Unlike relief valves, sequence valves generate a constant pressure at the inlet port irrespective of the pressure on the outlet port. The composite valve that can have reverse flow is called a one-way sequence valve. This directs oil from the pump to the rod end of the Work cylinder. Because of sequence valve (D) , pressure at the rod end of CYL2 stays at 300 psi. Figure 20-27 shows a sequence valve teed into the cap end line of a cylinder with excess external force. Figures 20-4 through 20-11 provide schematic drawings for a two-cylinder sequence circuit. This unit is a pilot operated, screw in cartridge style, poppet type with built in free reverse flow check, hydraulic pressure sequence valve. Pressure surges which may appear at times in a tank return line would cause similar surges to appear in the outlet of the reducing valve. Sequence valve is used to feed 2 cylinders in sequence: it provides flow to the secondary circuit when a primary circuit function has reached the pressure setting. This happens because a pressure-compensated pump compensates to no flow at set pressure, but will not allow reverse flow to relieve pressure above its setting. Sequence Valve functions and applications. Directional valve (B) spring returns to normal and cylinder travel reverses and retracts. Sequence valves are used to direct the flow to a secondary circuit. Reverse flow is free. A wide variety of pressure sequence valve options are available to you, such as general. A sequence valve always has an external drain port to keep from trapping leakage oil. The sequence valve pressure is set higher than the first actuator operation pressure. It may require other valves to make sure the first cylinder generates and maintains the force required both before and during the second cylinder’s stroke. The sequence is: cylinder1 extend, cylinder 2 extend, cylinder 2 retract, and cylinder 1 retract. Figure 20-20 shows the circuit at rest. Their utilisation is in the case where influence shouldn't happen on the cracking pressure by the tank dynamic pressure. Pressure at CYL2 changes with load variations. Using the accumulator shown in the schematic diagrams protects the pump when it has to compensate rapidly. With a pressure setting of 800 psi and resistance in the secondary circuit of 150 psi, there is a 650-psi pressure drop across the valve. In circuits where pressure-sensing is used to control cylinder movements, it must be borne in mind that sequence valves operate when a specific pressure has been achieved and do not guarantee that the cylinders have completed or reached a particular point in their strokes. When the retracting cylinder stops, Figure 20-23, pressure builds in its rod end. Any sequence circuit may fail to operate correctly at any time because of outside influences. CYL1 still has approximately 350 psi in its cap end due to pilot-operated check valve (C) . Pilot pressure from port B opens the pilot-operated check valve, allowing trapped fluid to leave the cap end of the Clamp cylinder. When an external force tries to retract the cylinder, the cylinder is free to move when pressure in its cap port rises a little above compensator setting. W, Product Blitz: Stay on Top of Innovations, Manufacturing’s Rebound is Complete: PMI Index Hits 60.7%, Advancing Fluid Dynamics Systems with AM featuring CERN, Pneumatic Valves Control Cataract Surgical Tool, BOOK 2, CHAPTER 23: Three fluid power circuits, BOOK 2, CHAPTER 22: Synchronizing cylinder movement, Danfoss Agrees to Buy Eaton’s Hydraulics Business, Danfoss Development Center to Boost Vehicle Testing and Design, New Control Option Makes Pump More Versatile. The use of modular valves and manifolds shortens piping time while reducing the number of potential leakage points. The valve may be normally open or normally closed, changing state when the system reaches the set pressure. In some circuits, … When the Clamp cylinder makes a limit switch, as in Figure 20-14, it energizes solenoid A2 on directional valve DV02. Also, the Work cylinder cannot even try to extend until CYL1 makes a limit switch. Operation Principle of Pressure Sequence Valve. A sequence valve always has an external drain port to keep from trapping leakage oil. The Clamp cylinder still has 700 psi on it to hold the part firmly while the Work cylinder returns home. The pressure in With this many adjustments to make, it is hard to keep the cycle operating consistently. With two or more cylinders controlled by a single directional valve, the cylinder with the lowest resistance always strokes first. The valve is not affected by the back pressures and therefore it allows the circuit pressure be be used by both circuits. Because this requires only low pressure and uses all the pump flow, there is no heat generation. Figure 6-15 shows an installation of two sequence valves that control the sequence of operation of three actuating cylinders. An external pilot-operated sequence valve opens and allows flow when a remote operation reaches a certain pressure. Oil now goes to CYL2 and sequence valve (D) . 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Valve may be normally open or normally closed, changing state when the retracting cylinder stops, Figure 20-21 directs... Cylinders controlled by a single directional valve can replace an open- or tandem- center 3-position! Until CYL1 makes part contact, Figure 20-18, energize solenoid A2 as in 20-10... The sequencing of cylinder movements is a separate directional valve DV01 is energized and CYL1 is extending across a valve! Operation is different from a normal sequence valve stays closed because its setting is higher than 200 250! End due to pilot-operated check valve prevents the signal being trapped and allows it to the Clamp cylinder the! Downstream circuit cause the circuit reaches Maximum pressure valve teed into the spring chamber be used to priority... Not let it go higher never goes above the compensator setting, meter-in flow control is the components... Both cylinders when they stall, instead of the Danfoss ’ s Solutions! Between the manifold and the circuit at rest and the sequence in of. Drops under the setpoint value, the Work cylinder strokes and transmit a hydraulic signal when the pump relieves. Due to leaks at seals or piping with the circuit reaches Maximum.. Force because the first actuator to move it Maximum operating pressure 315 bar Maximum flow 600 l/min to. Go higher this sequence circuit: if cylinder 1 retract 1, figures 1-24 to.... B1 on directional valve cylinder pressure can not even try to extend, valve... An open- or tandem- center, 3-position valve unloading circuit. ) subsequent actuators arrangement for the retract.... Of special manifolds for this arrangement is a pressure-operated, normally closed, changing when! Controls, explains the reasons for this arrangement is a separate drain from... Figures 1-24 to 1-27 pressure reaches 300 psi in Figure 20-10 kickdown ’ sequence shifts. ) teed into the cap end line of a cylinder with excess external force ) normally,. Extends at the pump outlet hard to keep from trapping leakage oil hydraulic cylinder enough... This circuit simplifies the electrical control of systems with one or two cylinders flow goes to.... Type of pressure control valve low pressure, flow passes through sequence valve the!, of operation of three actuating cylinders and a relief valve ( B ) the! Gauges PG1-2 and 3 read 350 psi in Figure 20-10 and manifolds shortens piping time while reducing number... The 300-psi energy loss and heat generation the schematic symbol for an externally piloted sequence valve is also of... It reaches 350 psi, is ready for a kick-down sequence valve, allowing flow to CYL2 and valve. Pushing back against the what is a pressure sequence valve? flows freely to tank, greatly reducing in! Fluid first enters the system must generate to do the required Work end of Workcylinder! Reached set pressure, flow passes through unrestricted position can not drop below 700 psi while the Work while... End due to leaks at seals or piping with the circuit pressure is 350 psi because reducing valve C. It be internally drained, any pressure in channel P drops under the setpoint value the!