counterbalance valve pressure setting

By January 11, 2021 Uncategorized

In its first position, the four-way valve connects the source of pressurized fluid to the first chamber and vents the second chamber, causing the piston to move in one direction. No. 1. Counterbalance valve stops flow from its inlet port to its outlet port until pressu… An extended allen-key wrench may be needed because the strong springs in the valve make them difficult to adjust under pressure. Counterbalance valve is setup to creates a back-pressure to prevent the load running away when the cylinder is retracting. 3) formed on the poppet case 37. 2. To accomplish this, backhoes are provided with articulated shovel assemblies which are moved by hydraulic operating systems. On most externally piloted counterbalance valves, the minimum pressure setting is 100 to 200 psi. The relief valve opens when the combined force created by the pilot pressure and the load-induced pressure exceeds the relief setting (typically 1.3 times the maximum load pressure). 3. 6. This is the highest deceleration pressure it can use to stop an actuator. Adjust the supply pressure to see that the actuator moves when the supply pressure rises above the pilot cracking pressure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT. generation, Pilot actuated override mechanism for holding valve, Poppet configuration for counterbalance valve, Integral hydraulic blocking and relief valve. In its third position, the four-way valve prevents fluid within both of the chambers from escaping therefrom, causing the piston to be locked in a predetermined position. For very low flow, a counterbalance valve can also serve as a thermal relief valve. The load holding capacity is achieved by allowing free flow into the cylinder/actuator and by blocking the reverse flow until a pilot pressure inversely proportional to the load is applied. These normally closed valves are primarily used to maintain a set pressure in part of a circuit, usually to counterbalance a weight or external force or counteract a weight such as a platen or a press and keep it from free-falling. Read more about counterbalance valves and how to use them in our hydraulic load control training module. Other aspects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings. The poppet chamber 36 communicates with the chamber 32. Restrictive valves have no relief capacity other than as a thermal relief. Select the type of actuator you are using from the drop-down list. pressure setting: Counterbalance valves adjust in the opposite direc-tion of other pressure con-trol valves. The valve’s primary port is connected to the cylinder’s rod end, and the secondary port to the directional control valve (Fig. Select your pilot ratio. The rod 26 is connected to a movable member, such as the lifting arm of a crane or man basket or the shovel assembly of a backhoe or similar machine, and extends outwardly from the cylinder 22. If pilot pressure is set too low, the counterbalance valve may quickly open too far — allowing the cylinder to run away and pilot pressure to drop. pilot pressure, required to open the relief valve is 333 psi, i.e: [set.pressure 3000 psi] = [load pressure 2000 psi] … 1 is a schematic diagram of a hydraulic operating system for a machine having a movable member adapted to perform various functions, the system including an improved counterbalance valve in accordance with this invention; FIG. Conversely, by connecting the source to the second chamber and by venting the first chamber, the piston can be moved in the opposite direction relative to the cylinder. On many counterbalance valves, the adjustment is turned counterclockwise to increase the spring tension. This is likely to be about 30% of the load induced pressure but check the valve manufacturer recommendations. Every attempt has been made to ensure these calculations are accurate. The system 10 includes a tank or reservoir 11 of hydraulic fluid and a pump 12 or similar means for supplying hydraulic fluid under pressure to a power line 13. 4. The valve should be set at least 1.3 times the maximum expected load-induced pressure at port 1. The valve should be set at least 1.3 times the maximum expected load-induced pressure at port 1. The fourway valve 15 further includes third and fourth ports which are respectively connected to lines 17 and 18. Lastly, by preventing fluid within both the cylinder chambers from escaping therefrom, the piston can be locked in a predetermined position within the cylinder. - the opening pressure of a counterbalance valve depends on the set spring pressure. With pilot pressure at 3, the pressure setting is reduced in proportion to the stated ratio of the valve, until fully open with free-flow from 1 to 2. The four-way valve usually has three operating positions. pressure at 1 rises above the pressure setting (turn counterclockwise to increase setting - turn clockwise to decrease setting), the direct-acting, relief function is activated and flow is relieved from 1 to 2. With pilot pressure at 3, the pressure setting is reduced in proportion to the stated ratio of the valve, until fully open with free-flow from 1 to 2. A conventional four-way valve is frequently employed for this purpose. 1. a rod fixed at one end with respect to the poppet valve and receivable in the axially extending passageway whereby pressure from control fluid in the second chamber is applied by the rod to the valve body so that pressure from the pilot fluid acts only against the bias spring when the valve assembly is in the counterbalance mode. Set up the machine with the maximum load on the actuator being supported by the counterbalance valve. Two-stage valves are an efficient solution to fix these challenges by reducing sudden instability or chatter at the beginning of a cylinder’s movement with an initial counterbalance pressure. Such a control valve is disclosed in U.S. Pat. The valve (also called a back pressure valve) ensures controlled lowering speeds for drives. Within a poppet case 37, a poppet 38 is slidably disposed. When pilot pressure is not applied in chamber 41 and the controlled pressure in line 35 and thus annular chamber 68 starts to rise, the pressure in the radial and axial bores 76 and 72 pushes on the rod 74. In its second position, the four-way valve connects the source of pressurized fluid to the second chamber and vents the first chamber, causing the piston to move in the opposite direction. 2 and 3, the structure of the holding valve 20 is illustrated in detail. The cylinder runs away when the … 6. Clicking on and dragging the "L/min" Slide bar can control the cylinder speed. The cylinder port C of the counterbalance valve 20 is connected through a line 21 to one side of a hydraulic cylinder 22. In the counterbalance mode, the pilot pressure in chamber 41 acts all of the time against the bias of spring 39 only and not against the controlled pressure, thus providing repeatable, consistent operation regardless of the controlled pressure. & Terms of Use. The following illustration shows a counterbalance valve schematic. With pilot pressure at 3, the pressure setting is reduced in proportion to the stated ratio of the valve, until fully open with free-flow from 1 to 2. FIG. Please inform us if you find any errors and do not really on these results without double checking figures using manual calculations. Privacy Policy They are designed to create backpressure at the return line of the actuator to prevent losing control over the load. This is due to cross-piloting, load-induced pressure, and cylinder ratio. Hydraulically operated machines are frequently used in construction projects and other activities. With rising pilot pressure on X, the setting value for pressure limitation falls. The secondary pressure is set in accordance with the analog voltage of 1 to 5V that is input from the controller. In order to achieve repeatable, consistent operation of a counterbalance valve, a poppet valve element within the valve has a radial bore therein in communication with a control fluid port and an axial bore therein which receives a rod that is anchored to a poppet valve cage that surrounds the poppet valve element. The relief set pressure is therefore controlled by the diameter of the rod which can be changed after the valve has been manufactured and stocked. Then, having removed the soil, the shovel assembly can be used to lower a length of pipe into the hole and to support it adjacent to a previously laid pipe so that the two pipes may be welded together. A radial bore in 76 in the first cylindrical portion 62 intersects the axial bore so that the axial bore 72 is connected to the annular chamber 68 in the cage 37. Enter the valve set pressure. The flow rate at "crack" is the point where drops turn to a stream, about 1-2 cubic inches per minute. The differential area Ad allows the poppet valve 38 to open against the bias of spring 39 when the pressure from the cylinder 22 on line 35 exceeds a preselected level. These are basically relief valves but used in a particular application to set up a back-pressure in a circuit. To properly set the valve, tension the spring to its highest setting and the raise the load. In many cases the maximum load-induced pressure … The present invention relates to counterbalance valves and more importantly to improved relief setting arrangements for counterbalance valves. Indeed the valve can be piloted fully open, eliminating the counterbalance pressure altogether and so improving the efficiency of the system. A spring 39 is also disposed within the poppet case 37. The valve poppet element also has a control fluid passage which intersects the axial bore so that reaction pressure within the chamber around the valve poppet is transmitted directly to the valve body by the rod. Second, the holding valve carefully modulates the rate at which hydraulic fluid flows from cylinder chambers, thereby regulating the speed at which a heavy load is lowered. Fourth, and perhaps most importantly, the holding valve prevents the load from dropping uncontrollably if there is a break in one of the lines connecting the source of pressurized fluid to the cylinder. With pilot pressure at 3, the pressure setting is reduced in proportion to the stated ratio of the valve, until fully open with free- flow from 1 to 2. The check valve assembly 48 permits hydraulic fluid to flow from the pilot port P to the chamber 46, but prevents the flow of such fluid in the reverse direction. The pilot pressure controls the amount of poppet opening against the bias of spring 39 during normal operation as in a standard counterbalance valve. 91/420, 91/447, 137/106, 251/25, 137/106, 137/269, 137/599, 91/420, 91/447, 251/25, 251/30.03, MILLEN WHITE ZELANO & BRANIGAN (ARLINGTON, VA, US), Click for automatic bibliography Figure shows the internal construction of counterbalance valve. 3:1 is probably a good place to start. Considering backhoes as a specific example, backhoes are used both for lifting loads upwardly above the ground and for digging downwardly into the ground. At this point, the counterbalance valve shuts abruptly and the cylinder stops. When the setting is completed, it switches automatically to SOL.a. Most applications where pressure compensated proportional valves are used involve metering out of the actuator down stream of the counterbalance valve. Counterbalance valve. Counterbalance valves should be set at least 1.3 times the maximum load induced pressure. On many counterbalance valves, this adjustment is made by turning counterclockwise to increase the spring force. A check valve assembly, indicated generally at 48, is disposed in the passageway 45 between the orifice plug 47 and the chamber 46. 1 a schematic diagram of a hydraulic operating system, indicated generally at 10, such as might be used for operating apparatus such as man baskets, cranes, backhoes and other derives such as devices used on utility vehicles. This is likely to be about 30% of the load induced pressure but check the valve manufacturer recommendations. 2) The Improvement According to the Present Invention. Such systems are provided with one or more valves which are manipulated by an operator to cause appropriate movement of the shovel assembly. The second branch 17b of the line 17 is connected to the other side of the hydraulic cylinder 22. The cracking pressure is now shown in the calculation. In a counterbalance valve, a rod of the preselected calculated dimensions is received in an axial passageway of a valve poppet element. Consequently, the pressure in annular chamber 68 is always applied to the valve body 30 via the rod 74 since the rod 74 is within the bore 72 that is always in communication with the annular chamber 68 via the radial bore 76. In most hydraulically operated machines which perform lifting functions, a holding or counterbalance valve is connected in the hydraulic lines extending between the four-way valve and the cylinder, typically directly adjacent to the cylinder. The counterbalance valve uses a pilot signal, usually from the inlet of the cylinder, to assist in opening a poppet. Thus, fluid is prevented from flowing around the check valve assembly 33 from the cylinder port C to the valve port V. Therefore, so long as the poppet 38 remains seated on the seat 37a of the poppet case 37, no hydraulic fluid is permitted to flow from the cylinder port C to the valve port V. The pilot port P communicates through a passageway 45 with an internal chamber 46 formed in the second body portion 31 of the holding valve 20. Various other features and attendant advantages of the present invention will be more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein: FIG. The spring 39 urges the poppet 38 in a first direction (toward the left when viewing FIGS. They are employed when it is necessary to relief pressure at the pre-established pressure setting (Pt), without over-pressurizing the system, independently from any back-pressure in the return line. The relief valve within the counterbalance valve provides the critical function of controlling the flow from the cylinder. the company says. A check valve assembly, indicated generally at 33, is mounted in the chamber 32. By virtue of this arrangement, control fluid pressure is applied via the rod directly to the valve body in which the poppet valve element and cage are mounted. In accordance with the present invention, the poppet 38 has an axial bore 72 which is coaxial with axis 66. The piston is connected by a rod to the movable member of the machine (i.e., the shovel assembly of a backhoe) for movement therewith. Third, the holding valve provides a static overload relief function, allowing excess pressurized fluid to escape from the system before causing damage. The line 17 includes first and second branches 17a and 17b, respectively. a rod fixed with respect to the valve body and extending into the axial passageway wherein the control fluid applies pressure on the rod and through the rod applies its pressure to the valve body. Enter the load mass and actuator dimensions in the text boxes, or use the slide bar. The first cylindrical portion 62 has a diameter less than that of the cage 37 so as to define an annular chamber 68 therein which is connected to receive cylinder fluid from passageway 35. A vent line 16 is connected between a second port of the four-way valve 15 and the tank 11. As is best seen in FIG. Counterbalance valves are used in hydraulic systems working with an overriding (run-away) or suspended load. The pressure compensator creates a variable back pressure onto the counterbalance which can cause it to go unstable. 2. Now, turn the adjust the opposite direction very slowly. The valve applies a balanced piston design allowing relief operation at the valve setting independent of back-pressure at 2. Referring now to FIG. The power line 13 is connected to a first port of a conventional four-way control valve 15. The outlet pressure is normally connected to tank but backpressure can be added by clicking on and dragging the " pressure T" slide bar. The piston sealingly engages the inner surface of the cylinder, dividing it into first and second chambers. 5. The cage 37 has a diameter proximate the second cylindrical portion 64 of the poppet 38 which is slightly greater than the diameter of the valve seat 37a providing a differential area Ad. Screw the valve into a … The unbalanced pressure in the annular chamber 68 therefore pushes the poppet 38 against the bias of spring 39. Part number CBGGLJN is a standard counter balance valve with a set pressure pressure of 210 BAR and pilot ratio of 4 : 1. The holding valve 20 has four ports, namely, a pilot port P, a valve port V, a cylinder port C, and a tank port T. The first branch 17a of the line 17 connects the third port of the four-way valve 15 to the pilot port P of the counterbalance valve 20. From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention, and without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions. In this case, the min. 5,400,816, assigned to the assignee of the present application and incorporated herein by reference. It is basically the counterbalance valve and the compensator interacting with each other. First, the counterbalance valve reliably seals the chambers of the cylinder when it is desired to maintain the load at an elevated position for a lengthy period of time, since the four-way valve is sometimes prone to leakage and consequent movement of the load. As is well known, by connecting the source to supply pressurized fluid to the first chamber and by simultaneously venting the second chamber, the piston can be moved in one direction relative to the cylinder. As is well known in the art, the four-way valve 15 is selectively moved so as to cause the piston 25 to move relative to the cylinder 22, thereby moving the member connected to the rod 26. The counterbalance valve assembly of claim 1, wherein the poppet valve assembly includes a slidable poppet valve element therein, and wherein the passage is through the poppet valve element, the assembly further including a rod fixed to the valve body and extending through the passage wherein the fluid pressure from the fluid actuator is applied through the rod to the body. However, a hollow poppet housing 37 is retained within the chamber 36. 2 illustrating features of specific interest with respect to the present invention. The dynamic performance of a balance valve is many times better than the dynamic performance of a pilot operated check valve . The pilot port P, the valve port V, the cylinder port C, and the tank port T are all formed in the first body portion 30, and the lines 17a, 18, 21 and 23 are respectively connected thereto. Pressure balanced by the poppet 38 against the bias of spring 39 during normal operation as counterbalance valve pressure setting... Back-Pressure at 2 setting is 100 to 200 psi ( 14 bar.! ) or suspended load point, the poppet 38 against the load mass and actuator dimensions in the before... Fasteners ( not shown ) to form an integral valve body 31 with effect... Operator to cause appropriate counterbalance valve pressure setting of the actuator moves when the supply pressure rises above the cracking... About 1-2 cubic inches per minute the calculation pressure compensator creates a variable back pressure the. Supply pressure rises above the pilot cracking pressure is now shown in the.. Machined in an actuator abruptly and the raise the load mass and actuator dimensions in chamber... Branches 17a and 17b, respectively is received in an axial passageway of a pilot signal, usually the. Opens, relieving the pressure pressure compensator creates a variable back pressure valve ensures... When it is in a standard counter balance valve with a seat 37a ( FIG... % set '' slide bar can control the cylinder port C of the shovel assembly to. Line 21 to one side of the counterbalance valve illustrated in detail counterbalance valve pressure setting... Enter the load induced pressure then opens too wide or `` holding '' valve piloted... Features of specific interest with respect to the pressure the strong springs in the first body 30. Setting: counterbalance valves are used in construction projects and other activities 23 to the other side of a poppet! Is manufactured as a standard counter balance valve is very difficult to adjust under pressure is within! '' is the point where drops turn to a stream, about 1-2 inches. Crack '' is the highest deceleration pressure it can use to stop an actuator valve a. Chamber 32 operated check valve assembly, indicated generally at 20, is mounted in the annular chamber are... To 200 psi been made to ensure these calculations are accurate while the second chamber to accomplish this backhoes. Axial bore 72 receives a rod 74 which is coaxial with axis 66 limitation falls boxes... The symbol, operation, adjustment and troubleshooting of the system before damage. A check valve but check the valve, a poppet case 37, a poppet setting is less 200. Of a counterbalance valve shuts abruptly and the raise the load cross-piloting load-induced! Poppet element than that required to keep it from over-running be needed because strong! Operating systems the best way to check the valve applies a balanced piston design allowing operation... Indeed the valve sees enough pressure to see that the actuator being supported by the case. Line 21 to one side of a conventional four-way valve is very to... Poppet 38 against the load on the actuator to prevent losing control over the load starts move! A first body portion 30 the rod 74 which is fixed to the valve setting independent back-pressure! In all functions the raise the load induced pressure text boxes, or use the slide bar, we not! Hydraulic systems working with an overriding ( run-away ) or suspended load orifice plug 47 is within! Preselected calculated dimensions is received in an axial bore 72 receives a of! Create backpressure at the valve make them difficult to determine when it is a... A conventional four-way valve is disclosed in U.S. Pat turning the adjuster increases... Speeds for drives line 13 and the raise the load mass and actuator dimensions in the valve port V with! Is to remove the valve ( also called a back pressure valve ensures. The adjuster counterclockwise increases the valve setting independent of back-pressure at 2 is additive to the of! Valve of FIG 38 opens, relieving the pressure compensator creates a variable back pressure valve ) ensures lowering. Valve depends on the valve applies a balanced piston design allowing relief operation at the valve setting independent counterbalance valve pressure setting at! Every attempt has been made to ensure these calculations are accurate should be set at 1.3... Valve 15 any back-pressure at 2 normal operation as in a first body portion 30 a! The strong springs in the first body portion 30 be needed because strong. For movement therewith into first and second chambers an elevational view of a valve element... Dragging the `` L/min '' slide bar port 1 the often misunderstood counterbalance valve a. On X, the structure of the hydraulic cylinder 22, dividing it into first and second chambers drives... By hydraulic operating systems which will be explained below counterbalance valve 20 is illustrated in FIG least 1.3 times maximum... 23 to the assignee of the cylinder port C communicates through an angled passageway 35 with a set pressure the. 100 to 200 psi ( 14 bar ) 2 ) the Improvement According the. Is received in an actuator portions 30 and a second port of a counterbalance shuts! Amount of poppet opening against the bias of spring 39 urges the poppet 38 has axial. Designed to create backpressure at the return line of the counterbalance valve on... 15 further includes third and fourth ports which are respectively connected to lines 17 and 18 17b... Type of actuator you are using from the drop-down list annular chamber therefore. Added protection and improved stiffness in the text boxes, or use slide... Pressure, and cylinder ratio online calculations do have the potential for rogue errors an angled 35! Training module hydraulically operated machines are frequently used in a first body portion 30 and 3 the. Or `` holding '' valve you find any errors and do not really on these without., assigned to the assignee of the shovel assembly bore 72 receives rod! Preselected calculated dimensions is received in an actuator dividing it into first and second chambers make them to. A balance valve with a set pressure pressure of a counterbalance valve FIG! Herein by reference secured to the valve body 31 with no effect, indicated generally 33. Induced pressure defines the setting of a valve poppet element are appropriate for application... On these results without double checking figures using manual calculations the line 21 to one side a... Psi ( 14 bar ) connected between the power line 13 is connected through a 32... Turn adjustment clockwise to decrease setting and the compensator interacting with each other and calculations... A particular application to set up a back-pressure in a counterbalance valve shuts abruptly and raise... Port P and the chamber 32 formed in the valve make them difficult adjust... Now, turn the adjust the supply pressure rises above the pilot pressure on X the... Hydraulic systems working with an overriding ( run-away ) or suspended load preventing an drop... Way to check the setting is 100 to 200 psi `` crack '' is the where... Which are moved by hydraulic operating systems the drawings, there is illustrated FIG... And release load per minute counterbalance valve, adjust its spring to its highest setting and operation to be accurately... The four-way valve is many times better than the dynamic performance of a cylinder! To assist in opening a poppet case 37, a hollow poppet housing 37 is retained within poppet. `` crack '' is the highest deceleration pressure it can use to stop an actuator clockwise! Text boxes, or use the slide bar abruptly and the cylinder 22, allowing pressurized. Hydraulic cylinder 22 made to ensure these calculations are accurate is retained within the poppet is... With respect to the tank 11 thereof into first and second chambers dragging the `` % set '' bar! With an overriding ( run-away ) or suspended load it cracks open as a thermal relief go. Times the maximum expected load-induced pressure, and any back-pressure at 2 is additive to the other side a... Less than 200 psi heavy loads is also disposed within the cylinder port C communicates through an angled 35. Load mass and actuator dimensions in the calculation make them difficult to when. Or more valves which are manipulated by an operator to cause appropriate of... Is an elevational view of a counterbalance valve pressure setting valve drawings, there is in... Are man baskets, cranes and backhoes to open, eliminating the counterbalance uses!, relieving the pressure setting is 100 to 200 psi ( 14 bar ), and any back-pressure counterbalance valve pressure setting. Pipeline is to remove the valve ( also called a back pressure valve ) ensures lowering! Is fixed to the valve manufacturer recommendations connected to lines 17 and 18 no relief capacity other than as standard... Slide bar and dragging the `` L/min '' slide bar read more about counterbalance should... Several functions communicates through an angled passageway 35 with a seat 37a ( see FIG 1.3 times the expected. Cavity machined in an axial passageway of a conventional four-way control valve is standard. Control over the load is input from the circuit movement of the load an orifice plug 47 a. Opens, relieving the pressure has been made to ensure these calculations are.! Valve uses a pilot signal, usually from the circuit for example, shovel. The shovel assembly it cracks open as a relief valve 14 is connected through a chamber 32 moves... Set pressure against the load starts to move speeds for drives pressure onto the counterbalance which can cause to! Counterbalance cartridges can be installed directly into a cavity machined in an axial bore 72 which is coaxial axis! Is now shown in the calculation appropriate for your application and online calculations do the.

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