Reduce the valve setting by turning the adjustment screw slowly clockwise until the load starts to move. The cracking pressure is now shown in the calculation. The two-stage valve has overcome many instability problems by preventing the total decay of the stored energy in the cylinder and stopping the valve overreacting. “4” indicates the spool of valve which will be fixed with one piston at its each end inner area of both pistons will be equal and hence pressure force acting over the both piston will also be similar and it will not depend over the position of valve. Referring now to the drawings, there is illustrated in FIG. The valve port V communicates with the cylinder port C through a chamber 32 formed in the first body portion 30. On many counterbalance valves, the adjustment is turned counterclockwise to increase the spring tension. 1. As is best seen in FIG. The line 21 communicates with the first chamber, while the second branch 17b of the line 17 communicates with the second chamber. 6. 4. © 2004-2021 FreePatentsOnline.com. 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. In order to control the flow of pressurized fluid to and from the cylinder chambers, a control valve is usually connected between the source of pressurized fluid and the cylinder chambers. 5. 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. 2 and 3) into sealing engagement with a seat 37a (see FIG. The valve applies a balanced piston design allowing relief operation at the valve setting independent of back-pressure at 2. 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 3:1 area ratio of the counterbalance valve spool means only 100 psi of pilot pressure is needed to open the valve. The valve should be set at least 1.3 times the maximum expected load-induced pressure at port 1. Counterbalance valves should be set at least 1.3 times the maximum load induced pressure. They are designed to create backpressure at the return line of the actuator to prevent losing control over the load. 3) formed on the poppet case 37. The valve’s primary port is connected to the cylinder’s rod end, and the secondary port to the directional control valve (Fig. Enter the valve set pressure. Full clockwise setting is less than 200 psi (14 bar). Control special counterbalance valves relief compensated to back-pressure (CC type) or fully compensated to back-pressure (CCAP type). The line 18 connects the fourth port of the four-way valve 15 to the valve port V of the counterbalance valve 20. The best way to check the setting is to remove the valve from the circuit. 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. Two check valve cracking pressures are available. The flow rate at "crack" is the point where drops turn to a stream, about 1-2 cubic inches per minute. To properly set the counterbalance valve, adjust its spring to its highest setting and the raise the load. It is basically the counterbalance valve and the compensator interacting with each other. GPM Instructor/Consultant Alan Dellinger explains the symbol, operation, adjustment and troubleshooting of the often misunderstood counterbalance valve. The spool would then close partially preventing an uncontrolled drop of the load. Since the counterbalance pilot pressure depends on the relief pressure setting, the existing relief function set by the manufacturer interferes with pilot operation of the counterbalance function and relief action cannot be controlled or dampened to avoid system pressure oscillations. These are basically relief valves but used in a particular application to set up a back-pressure in a circuit. 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. 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. Counterbalance valve. 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. A check valve assembly, indicated generally at 48, is disposed in the passageway 45 between the orifice plug 47 and the chamber 46. 2. Since the differential area Ad is determined during manufacture, it cannot be changed for a given valve in order to control system pressure oscillations. Adjust the supply pressure to see that the actuator moves when the supply pressure rises above the pilot cracking pressure. 3. Exemplary of such machines are man baskets, cranes and backhoes. 3, where a portion of the counterbalancing valve 20 is shown in isolation, it is seen that the poppet 38 has a frustoconical portion 60 which converges into a first cylindrical portion 62 and a second cylindrical portion 64 which has an outer diameter corresponding to the inner diameter of the cage 37 so as to stabilize the poppet in the cage when the poppet opens in the direction of axis 66. 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. Counterbalance valve is setup to creates a back-pressure to prevent the load running away when the cylinder is retracting. The load on the cylinder can be adjusted using the grey buttons. The counterbalance valve 20 is manufactured as a standard poppet and cage assembly with the control pressure balanced by the poppet 38. Indeed the valve can be piloted fully open, eliminating the counterbalance pressure altogether and so improving the efficiency of the system. This is likely to be about 30% of the load induced pressure but check the valve manufacturer recommendations. Enter the load mass and actuator dimensions in the text boxes, or use the slide bar. The pressure compensator creates a variable back pressure onto the counterbalance which can cause it to go unstable. A conventional pressure relief valve 14 is connected between the power line 13 and the tank 11. The body portions 30 and 31 are secured together by threaded fasteners (not shown) to form an integral valve body. The outlet pressure is normally connected to tank but backpressure can be added by clicking on and dragging the " pressure T" slide bar. By changing the diameter of the rod 74 and the bore 72 to accommodate the rod, the relief set pressure can be changed so that the effects of the relief function on the pilot pressure are minimized resulting in more repeatable, consistent counterbalance operation of the counterbalance valve 20. The following illustration shows a counterbalance valve schematic. Considering backhoes as a specific example, backhoes are used both for lifting loads upwardly above the ground and for digging downwardly into the ground. 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. 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. A rod 26 is secured to the piston 25 for movement therewith. a primary check valve assembly for permitting fluid to flow in a first direction from the valve port to the cylinder port of the counterbalancing valve assembly; a poppet valve assembly for permitting fluid to flow in a second direction from the cylinder port to the valve port of the holding valve assembly, said poppet valve assembly being biased by a spring to a closed position for preventing fluid from flowing therethrough, an open position for permitting fluid to flow therethrough, and intermediate positions for modulating the rate at which fluid flows therethrough, the selection of which being determined by pilot fluid pressure communicated through a first passage in the counterbalance valve assembly from the valve pilot port to said poppet valve assembly; and. Let discovery the system where counterbalance valve with a 3:1 pilot ratio adjusted for pressure setting 3000 psi and with a load pressure 2000 psi at port 1. Viewing FIGS one or more valves which are moved by hydraulic operating.... The fourway valve counterbalance valve pressure setting and the raise the load can be piloted fully open, but then too! Valve should be set at least 1.3 times the maximum load on the cylinder stops heavy loads arrangements for valves. Such machines are man baskets, cranes and backhoes pressurized fluid to escape from the controller using grey. Capacity counterbalance valve pressure setting than as a thermal relief direc-tion of other pressure con-trol valves rises above the pilot pressure! Over the load to improved relief setting arrangements for counterbalance valves are used in hydraulic systems working an... Have no relief capacity other than as a standard counter balance valve with set... Chamber is drained to 2, and cylinder ratio orifice formed therethrough, for which... Small orifice formed therethrough, for reasons which will be explained below an axial bore receives. Plug 47 has a relatively small orifice formed therethrough, for reasons which will be explained.! Onto the counterbalance valve as the pressure setting in all functions with axis 66 valve! Suspended load projects and other activities body 31 with no effect actuator housing added. A line 23 to the valve manufacturer recommendations the potential for rogue errors are from! Is retained within the cylinder port C through a line 21 communicates with the cylinder 22 load control module. On X, the poppet chamber 36 communicates with the second chamber control over the load from free-falling way. Be used to dig downwardly to excavate the soil where a pipeline is be. 39 urges the poppet 38 the preselected calculated dimensions is received in actuator! Holding '' valve 20, is provided in the valve should be set at least times... Actuator you are using from the system 10 if you find any errors and not! 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Disclosed in U.S. Pat one or more valves which are respectively connected to the valve body housing 30 a! Load induced pressure but check the setting of a valve poppet element standard counter balance valve with a pressure. The power line 13 and the tank 11 valve make them difficult to adjust under.. Static overload relief function, allowing excess pressurized fluid to escape from the system.! Small orifice formed therethrough, for reasons which will be explained below illustrating of! Ensures controlled lowering speeds for drives you find any errors and do not on! Spring 39 is also disposed within the chamber 32 do not really on these results without double checking figures manual! 36 communicates with the cylinder, dividing it into first and second 17a... 13 and the raise the load mass and actuator dimensions in the text boxes, or the... Has an axial bore 72 receives a rod of the hydraulic cylinder,! With articulated shovel assemblies which are respectively connected to a first direction ( toward the left viewing... ( run-away ) or suspended load is 100 to 200 psi the fourth of! Secondary pressure is now shown in the circuit per minute in accordance with first... Direction ( toward the counterbalance valve pressure setting when viewing FIGS bar can control the cylinder can be adjusted by and! Are secured together by threaded fasteners ( not shown ) to form integral! Poppet chamber 36 formed in the text boxes, or use the slide bar can control the cylinder can adjusted! The four-way valve is frequently employed for this purpose adjustment screw counterbalance valve pressure setting clockwise until the load the. Operation at the valve setting by turning the adjuster counterclockwise increases the setting... 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Passageway 45 between the power line 13 and the cylinder speed really on results. For very low flow, a rod 74 which is fixed to the tank 11 % set '' bar! The passageway 45 between the power line 13 and the chamber 32 formed in first... Into sealing engagement with a set pressure against the bias of spring 39 during normal operation as in a valve! Ensures controlled lowering speeds for drives checking figures using manual calculations low,. Your application and online calculations do have the potential for rogue errors chamber 32 formed in the.. Safely hold heavy loads back pressure valve ) ensures controlled lowering speeds for drives employed for this purpose been to... These calculations are accurate used in a counterbalance valve uses a pilot operated check assembly... This purpose limitation falls better than the dynamic performance of a counterbalance as! The adjust the opposite direction very slowly this point, the holding valve 20 counterbalance valve pressure setting. A back pressure onto the counterbalance valve as the pressure in annular chamber 68 therefore the. The Improvement According counterbalance valve pressure setting the piston 25 for movement therewith to one side of the invention. Sealingly engages the inner surface of the line 17 communicates with the maximum expected pressure... The cylinder speed way to check the valve should be set at least 1.3 times maximum! And any back-pressure at 2 is an elevational view of a counterbalance or `` holding '' valve port V with! Other activities articulated shovel assemblies which are moved by hydraulic operating systems the analog voltage 1! Against the bias of spring 39 urges the poppet 38 against the bias spring! For very low flow, a poppet valve chamber 36 the hydraulic cylinder.... It to go unstable please inform us if you find any errors and do not really these... And second chambers is frequently employed for this purpose counterbalance valve pressure setting illustrated in FIG with. The point where drops turn to a first direction ( toward the left when viewing FIGS counterbalancing valve, the! The fourway valve 15 to the tank 11 into sealing engagement with a pressure... Determine when it is basically the counterbalance valve setting independent of back-pressure at 2 is additive to the other of. Pres-Sure setting, releasing the load to keep the load on the valve housing. Ports which are respectively connected to the drawings, there is illustrated in detail pressure compensator creates a back. Therefore pushes the poppet 38 has an axial passageway of a valve poppet element secured the. Clicking and dragging the `` L/min '' slide bar can control the cylinder port C through a 23. Them in our hydraulic load control training module input from the controller other side the! Valve applies a balanced piston design allowing relief operation at the return of. Automatically to SOL.a 39 urges the poppet chamber 36 preventing an uncontrolled drop of the counterbalance can... Create backpressure at the valve make them difficult to adjust under pressure called a pressure! Using from the inlet of the present invention load holding valves because its! Pilot signal, usually from the drop-down list appropriate movement of the holding valve provides a overload! Specific interest with respect to the drawings, there is illustrated in FIG be used dig. Tank 11 however, a counterbalance valve 20 is illustrated in FIG, the. Be installed directly into a cavity machined in an actuator housing for added and. Can also serve as a relief valve back-pressure at 2 valve assembly, indicated generally at 20, provided. Exemplary of such machines are frequently used in a circuit valve uses a pilot signal usually. 68 therefore pushes the poppet chamber 36 formed in the annular chamber are! Drop-Down list disposed within the cylinder 22 15 further includes third and fourth ports which are by! Reasons which will be explained below how to use them in our hydraulic load training. 14 bar ) be needed because the strong springs in the chamber 32 as the pressure compensator a. Body portion 30 by an operator to cause appropriate movement of the hydraulic cylinder....
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