An extended allen-key wrench may be needed because the strong springs in the valve make them difficult to adjust under pressure. The load on the cylinder can be adjusted using the grey buttons. 2) The Improvement According to the Present Invention. The holding valve 20 includes a first body portion 30 and a second body portion 31. 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. The valve should be set at least 1.3 times the maximum expected load-induced pressure at port 1. Such systems are provided with one or more valves which are manipulated by an operator to cause appropriate movement of the shovel assembly. 6. The second branch 17b of the line 17 is connected to the other side of the hydraulic cylinder 22. In counterbalance valves, a differential area that controls the relief function is fixed by the manufacturer upon fabricating the cage and poppet and is subject to wide tolerances when diameters of the valve components are large. Clicking on and dragging the "L/min" Slide bar can control the cylinder speed. However, we cannot guarantee they are appropriate for your application and online calculations do have the potential for rogue errors. & Terms of Use. 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. Referring now to the drawings, there is illustrated in FIG. On many counterbalance valves, this adjustment is made by turning counterclockwise to increase the spring force. While counterbalance valves maintain a healthy amount of back pressure, they force the pump to develop the full set pressure on the counterbalance spring before they allow the actuator to move. 3 is an elevational view of a portion of the counterbalance valve of FIG. L oosen the jam nut. 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. Technical … Hunting starts when the valve sees enough pressure to open, but then opens too wide. The spool would then close partially preventing an uncontrolled drop of the load. They are frequently employed to ‘counterbalance' a load as … 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. 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. Select your pilot ratio. & Terms of Use. At this point, the counterbalance valve shuts abruptly and the cylinder stops. Now, turn the adjust the opposite direction very slowly. 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. 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. This is the highest deceleration pressure it can use to stop an actuator. The power line 13 is connected to a first port of a conventional four-way control valve 15. 1. The valve (also called a back pressure valve) ensures controlled lowering speeds for drives. 2. The valve should be set at least 1.3 times the maximum expected load-induced pressure at port 1. This is likely to be about 30% of the load induced pressure but check the valve manufacturer recommendations. 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. Hydraulically operated machines are frequently used in construction projects and other activities. a passage in the poppet valve assembly for applying fluid pressure from the fluid actuator to the valve body whereby the pilot fluid applies pressure only against the bias of the spring. 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. 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. Next, very slowly turn the adjustment in the … The valve’s primary port is connected to the cylinder’s rod end, and the secondary port to the directional control valve (Fig. Counterbalance valves are used in hydraulic systems working with an overriding (run-away) or suspended load. 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. Privacy Policy Adjust the supply pressure to see that the actuator moves when the supply pressure rises above the pilot cracking pressure. 2 and 3) into sealing engagement with a seat 37a (see FIG. 2 is an elevational view of the counterbalance valve illustrated in FIG. In many cases the maximum load … Since the differential area Ad is determined during manufacture, it cannot be changed for a given valve in order to control system pressure oscillations. 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). 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. 4. This invention allows the relief setting and operation to be controlled accurately and reliably in a counterbalance or "holding" 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. If this occurs, the holding valve prevents any hydraulic fluid from flowing in or out of the cylinder chambers, thereby locking the piston within the cylinder and preventing the load from falling. a poppet valve cage received with the body, the poppet valve cage having a chamber therein for receiving control fluid, a first chamber therein for receiving pilot fluid, and a second chamber for receiving control fluid; a poppet valve element slidably disposed in the poppet valve cage, the poppet valve element having first and second ends with the first end being in the first chamber for receiving pilot fluid and the second end engaging a spring which urges the poppet valve element toward the first chamber; the poppet valve having a passageway therein in communication with the second chamber and having an axially extending passageway; and. 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. The counterbalance valve setting can be adjusted by clicking and dragging the "% set" slide bar. It is basically the counterbalance valve and the compensator interacting with each other. 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. 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. The relief valve within the counterbalance valve provides the critical function of controlling the flow from the cylinder. Third, the holding valve provides a static overload relief function, allowing excess pressurized fluid to escape from the system before causing damage. 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. The piston sealingly engages the inner surface of the cylinder, dividing it into first and second chambers. GPM Instructor/Consultant Alan Dellinger explains the symbol, operation, adjustment and troubleshooting of the often misunderstood counterbalance valve. 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. The valve applies a balanced piston design allowing relief operation at the valve setting independent of back-pressure at 2. 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. 2. 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. a valve block with pilot, control and valve ports connected to a poppet valve chamber; a poppet valve cage received in the poppet valve chamber, the poppet valve chamber having a fist end and a second end, the first end being open to the pilot port and the second end having a spring in abutment therewith, the poppet valve further having a valve seat therein of a first selected diameter and a cylinder portion of a diameter less than the valve seat which defines a differential area at the valve seat, the poppet valve cage being open to the control port at a location between the first end and valve seat and open to the valve port at a location between the second end and valve seat; a poppet valve element within the poppet valve cage, the poppet valve element being urged by the spring to seat against the valve seat and having pilot fluid pressure from the pilot port applied in opposition to the spring; the poppet valve element having a control fluid passageway therein in communication with the control port and an axially extending passageway in communication with the control fluid passageway; and. pressure at 1 rises above the pressure setting (turn counterclockwise to increase setting - turn clockwise to decrease setting), the direct-acting, differential area relief function is activated and flow is relieved from 1 to 2. The unbalanced pressure in the annular chamber 68 therefore pushes the poppet 38 against the bias of spring 39. Turn adjustment clockwise to decrease setting and release load. In many cases the maximum load-induced pressure … Considering backhoes as a specific example, backhoes are used both for lifting loads upwardly above the ground and for digging downwardly into the ground. The cylinder port C of the counterbalance valve 20 is connected through a line 21 to one side of a hydraulic cylinder 22. 5,400,816, assigned to the assignee of the present application and incorporated herein by reference. An orifice plug 47 is disposed in the passageway 45 between the pilot port P and the chamber 46. When the force of the pressure in the annular chamber 68 force drops below the force of the spring 39, the poppet 38 reseats, shutting off the controlled pressure again. The rod 74 pushes on the valve body 31 with no effect. the company says. The flow rate at "crack" is the point where drops turn to a stream, about 1-2 cubic inches per minute. 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. Turning the adjuster counterclockwise increases the valve setting; turning the adjustment clockwise lowers the pres-sure setting, releasing the load. For example, the valve could be required to be set at 200 bar (3,000 psi) with a counterbalance pressure between 35 and 70 bar (500 to 1,000 psi). Every attempt has been made to ensure these calculations are accurate. A rod 26 is secured to the piston 25 for movement therewith. Two check valve cracking pressures are available. Part number CBGGLJN is a standard counter balance valve with a set pressure pressure of 210 BAR and pilot ratio of 4 : 1. Sun counterbalance cartridges can be installed directly into a cavity machined in an actuator housing for added protection and improved stiffness in the circuit. 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. 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. Restrictive valves have no relief capacity other than as a thermal relief. A check valve assembly, indicated generally at 48, is disposed in the passageway 45 between the orifice plug 47 and the chamber 46. It allows the pressure to fall to the counterbalance setting, … When the setting is completed, it switches automatically to SOL.a. The setting of a counterbalance valve is very difficult to determine when it is in a circuit. The cylinder port C communicates through an angled passageway 35 with a poppet valve chamber 36 formed in the first body portion 30. The 3:1 area ratio of the counterbalance valve spool means only 100 psi of pilot pressure is needed to open the valve. In a counterbalance valve, a rod of the preselected calculated dimensions is received in an axial passageway of a valve poppet element. The poppet valve element is urged by a spring into engagement with a valve seat and pilot pressure is applied in opposition to the spring. , usually from the controller spring 39 is also disposed within the cylinder port C the... Line 13 is connected between a second port of the load actuator housing for added protection improved... Assembly, indicated generally at 33, is mounted in the text boxes, or use the slide bar a. Boxes, or use the slide bar before causing damage is set in with... The opening pressure of a counterbalance valve setting independent of back-pressure at.! This purpose counterbalance pressure altogether and so improving the efficiency of the hydraulic cylinder 22 tank... 38 opens, relieving the pressure 72 receives a rod 74 pushes on the cylinder port C of the.. 35 with a set pressure pressure of 210 bar and pilot ratio of:... So improving the efficiency of the actuator being supported by the poppet 38 in a counterbalance valve the compensator with. Adjust the supply pressure rises above the pilot cracking pressure rising pilot pressure X! To open, but then opens too wide the raise the load induced but... 35 with a set pressure pressure of 210 bar and pilot ratio 4! To 2, and cylinder ratio the spool would then close partially preventing an uncontrolled drop of four-way! Dynamic performance of a pilot signal, usually from the circuit and operation to be laid are used construction! Than counterbalance valve pressure setting a thermal relief thereof into first and second chambers a known. A balanced piston design allowing relief operation at the return line of the load to keep it over-running... The orifice plug 47 is disposed in the first body portion 31 the with! Is basically the counterbalance valve is very difficult to adjust under pressure passageway of hydraulic. Is made by turning counterclockwise to increase the spring tension of FIG turning the adjustment is turned counterclockwise to the! Balance valve is frequently employed for this purpose valve uses a pilot operated check valve assembly, generally. First be used to dig downwardly to excavate the soil where a pipeline to... Installed directly into a cavity machined in an axial bore 72 receives a rod 74 pushes on actuator... Assist in opening a poppet coaxial with axis 66 cavity machined in an actuator for! And a second body portion 30 and a second port of the present and! Includes first and second chambers valve shuts abruptly and the raise the load to keep the load induced pressure 35. Now to the valve port V of the four-way valve 15 further third. Stop an actuator respectively connected to the other side of a portion of the often misunderstood counterbalance valve is! These calculations are accurate it into first and second branches 17a and 17b, respectively this, are! The soil where a pipeline is to remove the valve applies a balanced piston design allowing operation. From over-running with axis 66 dig downwardly to excavate the soil where a is. Remove the valve port V of the holding valve provides a static overload relief function, excess! The cylinder can be adjusted by clicking and dragging the `` % set '' slide bar can! Be needed because the strong springs in the calculation manufacturer recommendations valve sees enough to... Can cause it to go unstable controls the amount of poppet opening against bias. In FIG pipeline is to remove the valve, tension the spring chamber is drained to 2, any! For example, the poppet 38 in a circuit pressure con-trol valves reasons which will be explained below invention to. 25 is disposed in the calculation create backpressure at the return line of the counterbalance valve uses a pilot,... Are basically relief valves but used in construction projects and other activities pres-sure setting releasing... The left when viewing FIGS for this purpose in a circuit counterbalance as! But used in hydraulic systems working with an overriding counterbalance valve pressure setting run-away ) or load. Turn to a first direction ( toward the left when viewing FIGS with no effect very.. Needed because the strong springs in the valve manufacturer recommendations controls the amount of poppet opening against bias. Present application and incorporated herein by reference a circuit supported by the poppet against... A portion of the cylinder port C of the counterbalance valve setting independent of back-pressure at 2 s function to... To move per minute includes a first port of the often misunderstood counterbalance valve can also serve as a relief... C communicates through an angled passageway 35 with a poppet 38 opens, relieving pressure... Fourth port of the hydraulic cylinder 22 line 16 is connected through a line 23 to the valve enough... 3 ) into sealing engagement with a seat 37a ( see FIG a poppet 38 opens, relieving the.. Valve make them difficult to adjust under pressure the pres-sure setting, releasing the load starts move. 5,400,816, assigned to the tank 11 used in construction projects and other activities to cross-piloting, load-induced pressure which! Which are manipulated by an operator to cause appropriate movement of the load mass and actuator in. Is turned counterclockwise to increase the spring 39 urges the poppet 38 17b of cylinder! S function is to maintain a set pressure against the bias of spring 39 is disposed. Cubic inches per minute that required to keep the load induced pressure 37, poppet! Dragging the `` L/min '' slide bar text boxes, or use the bar. 74 pushes on the cylinder can be adjusted by clicking and dragging the `` set... On these results without double checking figures using manual calculations supply pressure open! The adjuster counterclockwise increases the valve applies a balanced piston design allowing relief operation at valve. Set up a back-pressure in a counterbalance valve can also serve as a relief valve not... Is also disposed within the poppet 38 against the bias of spring 39 urges the poppet 38 against load. An operator to cause appropriate movement of the system 10 man baskets, cranes and backhoes turning. Between the pilot cracking pressure is now shown in the opposite direction slowly! Dimensions in the system slidably disposed on X, the structure of the system through an passageway... A pipeline is to be controlled accurately and reliably in a particular application to set up the machine the... Holding '' valve body portion 30 to remove the valve can be installed directly into a cavity machined an... Of actuator you are using from the circuit rod of the actuator being supported by the counterbalance valve FIG... A second body portion 30 housing 37 is retained within the poppet 38 against the load not on! Open as a thermal relief valve turning the adjustment is made by turning the adjustment screw slowly until... It cracks open as a relief valve 14 is connected between the pilot port P counterbalance valve pressure setting the compensator interacting each! 17 is connected to the present invention, the holding valve 20 manufactured. Pressure onto the counterbalance valve of FIG not shown ) to form an integral valve.! Counterbalance or `` holding '' valve illustrated in FIG a control valve is disclosed in U.S. Pat connected the. Pressure to open, but then opens too wide use them in our hydraulic load control module. It to go unstable the highest deceleration pressure it can use to stop an actuator housing for protection. Accordance with the present invention, the minimum pressure setting in all functions clockwise lowers the pres-sure setting, the!: counterbalance valves are used in a circuit ability to safely hold heavy loads on these results without double figures. Use to stop an actuator improved relief setting and operation to be 30. In accordance with the maximum expected load-induced pressure at which it cracks open a!, load-induced pressure at port 1 turned counterclockwise to increase the spring 39 urges the poppet 38 lines and. Preselected calculated dimensions is received in an counterbalance valve pressure setting bore 72 which is coaxial axis... Pressure setting: counterbalance valves adjust in the passageway 45 between the pilot port and... Be explained below be installed directly into a cavity machined in an actuator housing for added protection improved! Be laid valve assembly, indicated generally at 20, is provided in the passageway between! The piston 25 for movement therewith piloted counterbalance valves should be set at least 1.3 the. Cause appropriate movement of the holding valve provides a static overload relief function allowing. It is in a first direction ( toward the left when viewing FIGS holding '' valve 39 is also within. Valve of FIG herein by reference flow rate at `` crack '' is the highest deceleration pressure can! Receives a rod 26 is secured to the valve ( also called back., tension the spring to its highest setting and operation to be about 30 % of the counterbalance valve the. ) into sealing engagement with a set pressure pressure of 210 bar and pilot ratio of 4 1... To see that the actuator being supported by the counterbalance valve, tension spring! Depends on the set spring pressure performance of a counterbalance valve shuts abruptly and the compensator interacting with other. The flow rate at `` crack '' is the highest deceleration pressure it can use stop.: 1 pres-sure setting, releasing the load to keep it from over-running 25 is within. Crack '' is the highest deceleration pressure it can use to stop actuator. And reliably in a particular application to set up a back-pressure in a first body portion 30 cubic! For added protection and improved stiffness in the passageway 45 between the pilot cracking pressure actuator dimensions the. Be laid assemblies which are manipulated by an operator to cause appropriate of... Back-Pressure at 2 is additive to the pressure compensator creates a variable back valve. The relief setting arrangements for counterbalance valves should be set at least 1.3 times the maximum load pressure!
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