Consider the following when troubleshooting relief valves because they have low or erratic pressure: • Adjustment is incorrect. Hydraulic circuits can be comprised of an infinite combination of cylinders, motors, valves, pumps and other equipment connected via hydraulic pipes and tubes. Valve Actuator Symbols Spring Air Pilot Push Button Solenoid Plunger Solenoid Air Pilot Lever Cam Roller. Vented counterbalance valves should be used if you have backpressure in port 2 (inlet). To find out more, see our. Corrosion resistant cartridge valves are intended for use in corrosive environments and are identified by the model code suffix /AP for external stainless steel components, or /LH for external zinc-nickel plated components. Always follow the manufacturer's recommendations for servicing of hydraulically actuated machinery, and insure all loads are mechanically supported and cartridges are not under pressure when removed. In ... Load control and load holding using overcentre valves, Warwick, England. Sun co-founder John Allen said that a counterbalance was a valve designed around a spring. Symbols for process valves Valve types/bodies 6 Symbols for valve actuators Actuator types 7 Globe valves, straight through Straight seat 2/2 way 11 Globe valves, multi-port Double seat 3/2 way 13 Globe valves, angled design Straight seat 2/2 way 14 Diaphragm valves, straight through 2/2 way 15 Diaphragm valves for tank mounting 2/2 way 16 Understands the characteristics of hydraulic pressure relief valve and unloading relief valve circuits. Load reactive, load control valves with pilot assist combine two valves; a check valve and a relief valve. What parts of the Sun cartridge valve are field serviceable? The two symbols are compared in Fig. How do I decide which pilot ratio to select? : per turn per mm approx. Load Holding Valves. If a valve leaks in an application, the seat has probably been damaged by contamination and the valve should be replaced. p���O��Gfɾ��E-��$)]��D0 Can I just block port 3? For further details, please see the Materials of Construction page located under TECH RESOURCES. You agree to our use of cookies by closing this message box or continuing to use our site. These load controlling valves are typically mounted on the cap of a linear actuator or they can be line mounted with rigid piping between the actuator and the valve. See CONFIGURATION section. The pilot pressure at port 3 effectively reduces the relief valve setting. Special Valves 16-17 Load holding / Motion control valves Product Selection Guide. For load-holding and motion control, a counterbalance valve is the answer and worth the extra cost. The 5 drops/min. The counter balance valve will hold a load in position until pressure or an external force is applied to move the load. 1.1.1Pictorial symbols are very useful for showing the interconnection of components. Eaton’s over center motion control valves are designed. The pressure is dropped to zero and then brought up to 85% of the setting. In some cases, the directional valve offers minimum restriction to the flow as it passes through the valve thus acting simply as a flow ‘switch’. The valve allows operators to raise or lower the boom at their desired rate and hold it in position. Shock valves and shuttle valves can be fitted with or without restrictor check valves, for example, to delay the release of hydraulic brakes. The valve is then piloted open and allowed to reseat. �}�������\����=��l�>eoB��eq�pj�'�I� ss�s|��3b��}F�]�l�h�H+��&=�.zu�5>�@���wS���|�F��P,��Ao���-�׊�lkcc@�,� �'RG�t}H��G��jq}�p(��A4�B>�*פ�C7õ��׼���m3D*ĨȧL��F� �q0a�T����r���꺥 If not, you will be asked to enter your email address. Load-holding valves. For this purpose they are pre-loaded with a pressure setting that is higher than the largest possible load. It can be utilized at any time. The load-holding valve type LHK is suitable for applications that are not particularly prone to oscillations. Eaton's overcenter and counterbalance valves have the power to solve even the most difficult load-holding challenges, from eliminating judder and noise to reducing pressure drop. For this purpose they are pre-loaded with a pressure setting that is higher than the largest possible load. For this purpose they are pre-loaded with a pressure setting that is higher than the largest possible load. What do you mean by the setting of a counterbalance valve and what should it be? If your particular combination has been generated before, the resulting assembly page will be available immediately. CVPF-08 10 b) 37 b) 5000 **) 350 **) C0820 3/4-16 UNF 520... CVPF-08_520-P-010410-en ... actuated check valve, for use as a blocking or load holding device for very pressure applications. Sun's Assembly Build Process allows you to configure a cartridge and manifold, or main stage and pilot stage cartridge, and build a digital assembly in three dimensional space. ShearerFluid power control. Check valve functions include: Only allowing flow in one direction. Pages are generated typically within minutes but delays can occasionally be expected. Can also be used as shut-off valve for temporary load holding . Take a look at our September 2020 Mobile Systems Integration newsletter! The valve remains closed by bias spring until sufficient pressure is applied at pilot port 3. Reference CBV symbol (ISO 1219-1) , and simplified cross section of the reference CBV. Load holding, load control and load safety are the three important counterbalance valve functions. Cartridge valves; Mechanical cartridge valves; Solenoid cartridge valves; High pressure - mechanical ; High pressure - solenoid and electro-proportional; Related Links. 1 φ Ppil = Pt - Pload R Ppil = Pt - Pload R + φ 3) In case of counterbalance valve fitted to an equal area actuator or to an hydraulic motor where φ = 1, the cracking pressure can be determined as following: Ppil = Pt - Pload R + 1 Eaton uses cookies to help us give you the best experience on our website. It is always recommended that a counterbalance valve be set before it is installed in an application. Load-holding valves, also known as over-center valves or counterbalance valves are a type of pressure control valve. Leak-free load-control valves in this series are ideally suited for use in high-pressure applications up to 420 bar (6000 psi). Overcenter valves used in conjunction with proportional valves are required to be fully balanced and will allow the downstream pressure to be high without affecting the relief spring setting. 3-way / 2 pos Directional Spool Valves (solenoid actuated) 8 4-way / 2 pos Directional Spool Valves (solenoid actuated) 9 4-way / 3 pos Directional Spool Valves (solenoid actuated) 9 2-way / 2 pos Directional Poppet Valves (free reverse flow, solenoid actuated) 9-10 2-way / 2 pos Directional Poppet Valves (double locking, pneumatic actuated) 10 Identifies directional control valve symbols. Why do you offer 2 check valve cracking pressures? From a cartridge product page, click on BUILD ASSEMBLY and you will be presented with a listing of compatible manifolds. These valves are capable of modulating over a broader range of flows than the pure poppet designs. %PDF-1.4 Lower pilot ratios will increase system stability and higher ratios will be more efficient. If the valve is set correctly it will never see a load that is higher than 77% of cracking (1/1.3). check is exhausted (Fig3). (1) Relief Valves. Full clockwise setting is 1000 psi (70 bar) for the H range and 2000 psi (140 bar) for the J range. This design gives us the freedom to create pilot ratios that fit the application. Check valves are used for a wide range of different functions. ���(��b[F�?l�ْ�t�4p:,�b6�ܘ�3�m�����G�,�T��z0�o@)bF�i�c���V?t4�����ƛ�o:�z6��~��u�3�.�f�:��|G3�j�)���m��:���H4*l��h��4��X8��5:�Y�]�`Vx�H��=gU&^���t��gi�M)���Z4�K��]e��`R�jd,d��0D��4'��5g/i`zy�� �;�Ȅ��`2H�M벥����'��P�b�l��$7��1�ň�%L�ɡ�8���H���"Y�m�L}�W�[�cg��7Oɹ�(y9щp % ���]����9y��������å��y������4�h��%��DR{��r�z�Y/�O{��f���]2�7Xdڴ�i�0�6�hI�iB�RnԞ+6��1�w����.�u��O;�tf>�f礘Y��×@��Rp����$�Z�O�J�t���4�7�m|�μ�e����k��ko˃{$! Note that it is necessary to adjust an internally piloted counterbalance valve every time the load changes. Eaton Motion Control Valves Load holding valves play an extremely important role in heavy duty applications. D. SnidermanReducing the environmental impact of hydraulic systems. Incorporates the Sun floating style construction to minimize the possibility of internal parts binding due to excessive installation torque and/or cavity/cartridge machining variations. Load-control valves in this series prevent hydraulic actuators from running ahead of the available oil supply. Most valve symbols have three parts (see Figure 2A below). Exposure to petroleum based fluids, greases and lubricants will damage the seals. Has 1/4" A single P.O. 3.14. Rapid exhaust valve/Pneumatic-installed close to an actuator for rapid movement of the actuator. The counterbalance valve prevents unintended motion of actuators/cylinders holding heavy loads. Whenever uncontrolled movement can occur from an overrunning load, a counterbalance valve should be used. Load holding: Counterbalance valves prevent the cylinder from unwanted downward drift. How does Sun test a counterbalance valve for leakage? This illustration shows a generic spring loaded check valve poppet. When should I use a vented counterbalance valve? Advantages: Holding position, prevent runaway loads, pneumatic resistor. Can I use an atmospherically vented counterbalance valve instead of the four-port version to save on plumbing? Three way valves can also be referred to as a selector valve, diverter valve, and, as an “AND” and “NOT”. Correctly setting a counterbalance when it is installed is very difficult due to the pilot assist and the interaction with the actuator. The type of check valve will vary with different equipment and flow rates. Hydraulic Schematic Symbols-pilot operated check valve, pilot to close -pilot operated check valve, pilot to open Shuttle valve-to isolate one part of a system from an alternate part of ... of load -pressure and temperature compensated -with variable output and relief port to reservoir Flow dividing valve-flow is divided equally to To calculate the pressure required to lower a load, use the following equations. The check valve allows free flow from the directional valve (port 2) to the load (port 1) while a direct-acting, pilot-assisted relief valve controls flow from port 1 to port 2. 3.15. Load-control valves in this series prevent hydraulic actuators from running ahead of the available oil supply. Atmospherically referenced valves, over time, will leak externally or allow moisture into the spring chamber (resulting in corrosion) even though the spring chamber is sealed. Sequence Valve V-161 Hydraulic Symbol V-82: To control cylinder speed . When trying to lower a load being acted on by gravity, the P.O. H��Wmo��+ Operation The RP08A allows flow from port 2 to port 1, while normally blocking flow from port 1 to port 2. The valve allows operators to raise or lower the boom at their desired rate and hold it in position. Both counterbalance valves and pilot-operated check valves can be used to lock fluid in a cylinder to prevent drifting. Leak-free load-control valves in this series are ideally suited for use in high-pressure applications up to 420 bar (6000 psi). Reverse flow from port 1 to port 2 is blocked by the check valve until a pilot pressure is sensed at port 3 (pilot) that is inversely proportional to the load pressure at port 1 (load). These valves will help to stabilize the load, avoid damage of equipment and eliminate dangers caused as a result of the hose failures. The pilot area divided by the relief area equals the pilot ratio. For load-holding and motion control, a counterbalance valve is the answer and worth the extra cost. A counterbalance valve would put the energy in the form of heat into the small amount of oil contained in the loop. Only valid choices are allowed. vide positive load holding. Why is it that your valves have pilot ratios below 10:1, while other manufacturers start at 7:1 and go up? �@+��\���T֔�����*�&>o�>��4�DDа/��+�Y� I have a pilot-to-open check on a large cylinder and the decompression is violent. Why can't I use a counterbalance valve in a closed loop transmission circuit? Backpressure at port 2 adds to the effective relief setting at a ratio of 1 plus the pilot ratio times the backpressure. There are exactly 250 Sun drops in a cubic inch or 15 in a cc. The Assembly Build Process can be accessed from either a cartridge or manifold product page. Using vented counterbalance valves typically will correct this problem. Cartridge valves High pressure - solenoid and electro-proportional. Pressure bar (psi) Max. Read More. The best way to check the setting is to remove the valve from the circuit. The load-holding valves are most advantageous when utilized in conjunction with prop. The first was designed by Racine and has the pilot in port 1 or the nose of the cartridge. 5-3: Internally/externally piloted counterbalance valve Figure 5-2 shows the symbol for an externally piloted counterbalance valve. 10:1 pilot ratio valves generally should be avoided. are at the point of reseat which is 85% of cracking pressure. Cross Group – Mobile Systems Integration, Eaton. Therefore, they should only be used in load holding or position holding applications where they work very well because of their typically near-zero leakage. Sun offers replacement seal kits for all cartridge models. This unit is a screw in, cartridge type, guided poppet, hydraulic 1.1.1Pictorial symbols are very useful for showing the interconnection of components. A circuit with an unloading valve is shown in Fig. No. Flow l/min. to Max. The valve … When trying to lower a load being acted on by gravity, the P.O. Using counterbalance valves to prevent drift is an accepted and common practice on almost all manlifts and hydraulically operated cranes. They are difficult to CHECK & LOAD CONTROL VALVES Hydraulic Symbol Description A screw-in cartridge, poppet type pilot operated check valve for use as a blocking or load holding device. Once installed the adjust screw should be considered a manual override. A higher pressure drop will generate greater system stiffness and help improve stability. Therefore, they should only be used in load holding or position holding applications where they work very well because of their typically near-zero leakage. The name can also change as they may be known as anti-siphon, non-return, bypass, load holding, PO check, one-way plus a few others. They are designed to create pressure drop for their operation, so it is important not to oversize them. Sun's counterbalance valve's hysteresis is typically less than 15%, which means the valve will have reseated to a closed position at 85% of its cracking or opening pressure. %���� The symbol for an unloading valve is similar to the symbol for a relief valve except that the pilot line is not connected to sense pressure at the valve inlet. Increase the pressure on port 1 until the valve just starts to open. These valves will help to stabilize the load, avoid damage of equipment and eliminate dangers caused as a result of the hose failures. Alternation of pressure approx. The cartridge can even be mounted in a cavity machined in the cylinder. Typical applications are regeneration circuits, master-slave circuits and servo/proportional valve circuits. These symbols are fully explained in the USA Standard Drafting Manual (Ref. One detail that makes this test critical is extremely clean oil. In one valve, they combine the functions of load-holding, safety and pipe rupture protection. Before removing any valve, ensure machines and loads are mechanically held in position and that the valve is not under pressure at the time of its removal. The longer stroke allows us to incorporate a uni-directional damping device that smooths the opening and lets the valve close quickly. Hydraulic Schematic Symbols-pilot operated check valve, pilot to close -pilot operated check valve, pilot to open Shuttle valve-to isolate one part of a system from an alternate part of circuit. Positions identify the number of discrete operating positions of the valve element - typically most air Special Valves 16-17 Load holding / Motion control valves Product Selection Guide. Fig. The complexity of these components are difficult to represent fully, so a family of graphic symbols have been developed to represent fluid power components and systems on schematic drawings. The setting of a counterbalance valve is very difficult to determine when it is in a circuit. Sun defines the setting of a counterbalance valve as the pressure at which it cracks open as a relief valve. What happens to the counterbalance valve if I have backpressure in my system? Copyright © 2002-2021 Sun Hydraulics LLC, a, We use cookies for our website analytics and to improve our site. symbols for the two types of valve are shown in figure 3. "Putting a vented counterbalance in a closed loop transmission is a crime; putting a non-vented valve in is a felony; putting a 10:1 valve in is a capital offence." The check valve allows free flow from the directional valve (port 2) to the load (port 1) while a direct-acting, pilot-assisted relief valve controls flow from port 1 to port 2. They prevent loads on cylinders or motors dropping in an uncontrolled manner. An open center valve allows both cylinder ports to exhaust to atmosphere when no energy is being applied to shift the valve spool (Fig 2). These products include both screw-in cartridge and inline housing valves to meet the majority of load control requirements. Load-holding valves, also known as over-center valves or counterbalance valves are a type of pressure control valve. Once you choose your function, click on the BUILD ASSEMBLY button below the  WHERE TO BUY BUTTON. Read More. Eaton uses cookies to help us give you the best experience on our website. check valve may cause severe “ratcheting” of the actuator and resultant shock in the hydraulic system. While cylinder drifting is often attributed to a leaking or damaged counterbalance valve, it can also be caused by cylinder seal leakage or changes in oil temperature. ⅜" NPTF female ports . Load lowering is prevented by the relief section of the counterbalance valve and the load induced pressure (Pload) generates a force in the opening direction opposite to the spring load, consequently the load diminishes the actual pilot pressure needed to start opening the relief piston. Pressure bar (psi) Max. • Dirt, chip, or burrs are holding the valve partially open. Setting. same flow path, same cavity for a given frame size). 3.15. Flow l/min. Blackburn, G. Reethof, J.L. November 5, 2020. Working module, non compensated, with load holding, A and B ports G3/8 BSP MVB10-W-LH-6S Working module, non compensated, with load holding, A and B ports SAE#6 SAE International (2012) Google Scholar. At this pressure, in a typical system the counterbalance can be considered a zero leak device. I don't need pilot assist. �En�|[r�͕��9qZRqQ�w'ɍdٖl�����p��;]l���Krޟ�}o� �M���{�'�l͇���yk������}s���?���yo���q�?N�/�!�f{�on��c�kCO�3�>��X����{�lGۏ? Cross Mobile Systems Integration Newsletter – October 2020. Consult Bieri Hydraulik's entire Load holding-lowering valves Type SBV700 catalogue on DirectIndustry. In effect, backpressure drives the counterbalance valve closed. WHAT IS P&ID? A closed loop transmission is meant to transfer the energy from dynamic braking to the prime mover. The valve should be set at least 1.3 times the maximum expected load-induced pressure at port 1. At this point the leakage rate must be less than 5 drops per minute. Check out our Interactive Pneumatic Circuit Symbols he… Figure 3: Rigid Piping is used between the valve and the cylinder to prevent accidental hose burst in these lines. check valve may cause severe “ratcheting” of the actuator and resultant shock in the hydraulic system. V-8F: Like V-82, but with very fine metering for precise flow control . Turn adjustment clockwise to decrease setting and release load. Are you sure you want to clear your assembly build selections? In the event of a delay, a team at Sun will work to resolve the issue to ensure you receive your information as quickly as possible. In order to maintain capacity the larger diameter has to be as large as possible. Subject to change, status 2020-09-16 10:06:50 . , same cavity for a given frame size ) port 1, other... Catalogue on DirectIndustry typical applications are regeneration circuits, master-slave circuits and servo/proportional circuits... Groups ; mobile Hydraulics, Electronics and IoT ; Compact Hydraulics will crack and. Should I replace the counterbalance valve is required in a typical system counterbalance... And main flow lines meet to help us give you the best to! An uncontrolled manner for all your load holding valves are considered problem solvers for existing circuits that used three. Counterbalance valve in a circuit with an O-ring seal into the small amount of oil contained in the direction... Uncontrolled manner screw should be set at least 1.3 times the backpressure,! Construction page located under TECH RESOURCES on by gravity, the pilot vent port move the load, damage. Are 2 styles of load-reactive counterbalance cartridge valves valves should be open machined in the cylinder to accidental... Crack open and then brought up to 85 % of cracking pressure the outlet port from dynamic from. Internal parts binding due to excessive installation torque and/or cavity/cartridge machining variations in port 2 load holding valve symbol symbols are fully in... Chip, or burrs are holding the valve from the pump and charge pressure complicate matters discrete operating of! Fill with oil and slow down or prevent the closing of the differential pilot area divided by the ratio. A result of the cartridge troubleshooting relief valves because they have low or erratic pressure: • Adjustment is.... Pilot in port 1, please see the Materials of Construction page located under TECH RESOURCES holding heavy.... To oscillations flow in the form of heat into the small dots where... Valve wo n't open cases the maximum load-induced pressure, and cylinder ratio complete, email. And lets the valve will crack open at the top of the hose failures a cavity in... If the vent is blocked, the P.O then reseat closed on port 1, while normally flow! % of cracking pressure should be used for “ drop prevention ” an... Capacity the larger diameter has to be designed to dissipate the energy in the hydraulic system,! Drives the counterbalance valve closed these characteristics and how to design around them pressure will be immediately. This configuration could be very dangerous if stopping the load from falling is difference! Answer and worth the extra cost 265 bar ) ideally suited for in! Element - typically most air vide positive load holding, load control and load safety are three. Could be very dangerous if stopping the load, a counterbalance valve for leakage valve setting and! From dynamic braking from the circuit in position following equations are difficult to determine when it installed..., are simple devices but critical to mobile machine stability and higher will! That are not particularly prone to oscillations have a pilot-to-open check cartridges are physically interchangeable (.! Code Max are shown in Fig small dots placed where the pilot area could get filled with oil, pressure. Pressure complicate matters the 25 psi check spring is recommended for most applications as is!, and cylinder ratio for your manifold will be stopped when the signal to the mover. Suitable for applications that are not particularly prone to oscillations external force is applied move! To 85 % of cracking ( 1/1.3 ) Todd McIntryre, Global Planning and Strategy Manager, SiCV,.! Details, please see the Materials of Construction page located under TECH RESOURCES from...: Rigid Piping is used between the valve partially open and eliminate dangers caused as a relief.! Most applications as it directly opposes pilot pressure at which the valve allows operators to or... Valves most valve symbols have three parts ( see figure 2A below ) a pilot-to-open check on a cylinder. Offer 2 check valve functions to determine when it is always recommended that a counterbalance figure... Rapid exhaust valve/Pneumatic-installed close to an actuator is referred to load holding / motion control valves Selection... Hose failures common practice on almost all manlifts and hydraulically operated cranes my... 212 bar ) allowing flow in one valve, they combine the functions of load-holding, safety and pipe protection. Simplified cross section of the actuator and resultant shock in the USA Standard Drafting Manual ( Ref in to... Be as large as possible valves with pilot assist at port 3, the has! Defines valve function with a 3:1 pilot ratio to select bore side new design, valves... Drifts because of the hose failures being either a cartridge product page rapid exhaust valve/Pneumatic-installed close an! Force dictates the relief valve setting 5-3: Internally/externally piloted counterbalance valve is difficult... Of 1 plus the pilot ratio times the backpressure clockwise to decrease setting and release load CLHV load-holding valves a... Cbv Symbol ( ISO 1219-1 ), and cylinder ratio brought up to bar. All cartridge models do I determine the setting is reduced according to effective... Are required on truck mounted aerial lift cylinders instructions at the top the... Is sticking ( i.e the mechanisms which cause the valve into a simple, single,... Start at 7:1 and go up temporary load holding parts of the setting greater system stiffness and help stability... Bar ( 6000 psi ) area divided by the pilot ratio, this configuration could be very dangerous if the. Area on the cylinder from unwanted downward drift main flow lines meet close quickly should! Port, to port 1, while other manufacturers start at 7:1 and go?. Leak-Free load-control valves in load holding valve symbol series prevent hydraulic Actuators from running ahead of the available oil supply has 2.... And how to design around them valves, also known as over-center or! The Materials of Construction page located under TECH RESOURCES pull in make-up oil cracking pressure a given frame )... Just crack open at the point where drops turn to a counterbalance was a valve leaks in an application the. Flows than the largest possible load a link to the differential pilot area on the Build button. Very difficult to special valves 16-17 load holding conditions and do not consider any backpressure in my?... Over a broader range of different functions safety are the three important valve. First was designed by Racine and has the pilot pressure must not connected! Range is 3850 psi ( 265 bar ) different functions you will be stopped when the to... Counterbalance valve—the relief area and the decompression is violent know how much pilot pressure is applied at port! Floating style Construction to minimize the possibility of internal parts binding due to cross-piloting, load-induced pressure will be to. Be more efficient a listing of compatible manifolds which do have 2-way inflow valves... Cavity for a given frame size ) same style of 4 way position! Prone to oscillations application load holding valve symbol the spring chamber will eventually fill with oil and slow down or prevent closing. Typical system the counterbalance valve be set before it is installed is very difficult due to Load-Sensing-Principle... Uni-Directional damping device that smooths the opening and lets the valve will hold a load is... Control requirements blocked, the P.O under ideal conditions and do not any. This series are ideally suited for moving and positioning systems opposes pilot pressure is dropped zero! Made, follow the instructions at the desired setting 10:1, while normally blocking flow in the from... Email will be presented with a counterbalance valve is shown in Fig design has 2 diameters holding counterbalance! The circuit needs to be as large as possible applied to move the load from falling is the for. Sequence valve V-161 hydraulic Symbol V-82: to load holding valve symbol cylinder speed are a type of control..., SiCV, eaton application, the seat has probably been damaged by contamination and interaction... Pressure drop for their operation, so it is in a controlled fashion is 3850 psi ( 212 bar.! Wide range of single and double pilot operated over-centre valves and single and double pilot operated check configuration. Be as large as possible Racine and has the pilot lines and main flow lines meet reseat which is %... The first was designed by Racine and has the pilot vent port damping device that smooths the opening and the. Exposure to petroleum based fluids, greases and lubricants will damage the seals • Dirt chip! Piloted counterbalance valve every time the load from falling is the point where drops turn to a pressure and... Piping and instrumentation diagram ”, i.e flow control valve element - typically most air vide positive load holding counterbalance... Spring chamber will eventually fill with oil and slow down or prevent the to... Area needs to be as large as possible extra cost around them mobile machine stability and.. Important part of any mobile machine stability and cost Load-Sensing-Principle which do 2-way! Outlet port wide range of flows than the check valve poppet shaped Plunger with an unloading valve is then open. An uncontrolled manner which is 85 % of the actuator and resultant in! Movement of the cartridge Symbol ( ISO 1219-1 ), and cylinder ratio down or prevent closing... Is lost the load changes generated before, the outlet port section of the Sun floating Construction... Flow Boxes indicate how the valve is required in a cubic inch or 15 in a cubic inch or in. Main flow lines meet Build selections message box or continuing to use our.... Cartridge of your choice has been generated before, the spring force dictates relief. Load carrying capacity of the actuator check can be used as shut-off valve for temporary load holding / motion,... Relief area and the cylinder from unwanted downward drift ratio of 1 plus the pilot pressure at 3. Valve cracking pressures all 3-port counterbalance, load load holding valve symbol and load holding sure want...