Many types of hydraulic valves Below we will introduce several common problems of hydraulic valves and troubleshooting methods. See the following list: A common fault relief valve and deal with the following table: Analysis of the reasons for the failure to eliminate the method (a) can not adjust the pressure 1. The main valve failure (1) the main spool orifice clogging (assembly of the main spool (3) main valve return spring breaking or bending, so that the main valve The core can not be reset (1) to clean the orifice to make it clear; filter or replace the oil (2) open the overhaul, reassemble; bonnet fastening screw tightening force to be uniform; filter or replace the oil (3) replace the spring. Pilot Valve Malfunction (1) Pressure Spring Breaking (2) Pressure Spring Unloaded (3) Check Valve or Ball Not Installed (4) Check Valve Damaged (1) Replacement Spring (2) Replacement (3) Replacement 4) Replacement 3. Far-mouth solenoid valve failure or remote control port without plugging and direct fuel tank (1) Solenoid valve is not energized (normally open) (2) Slip valve stuck (3) Solenoid coil burned or iron core Stuck (4) electrical line fault (1) check the electrical circuit connected to the power (2) overhaul, (3) Replacement (4) Overhaul 4. Incorrect installation of the wrong oil inlet and outlet installation error 5. Hydraulic pump failure (1) The gap between the sliders is too large (such as gear pumps, piston pumps) (2) The blade stuck in the rotor slot (3) the direction of the blade and rotor mounted anti (1) repair the gap to the appropriate value (2) cleaning, repair the gap to the appropriate value (3) to correct the direction Fault (if the main valve is a cone valve) (1) The main spool cone surface sealing poor 1) The main spool cone wear or non-round 2) Seat cone wear or not round 3) 4) The main spool conical surface and the valve seat is not concentric 5) The main spool of work has stuck, the spool can not be tightly combined with the valve seat (2) Leakage at the main valve gland (such as gasket damage, assembly Defective, gland screws are loose, etc.) 1) Replacement and dosing 2) Replacement and dosing 3) Cleaning and dosing 4) Fixing to make it well 5) Fixing to make it fit well (2) Disassemble and replace the seal Pad, reassemble, and ensure that the screw tightening force evenly 2. Pilot valve failure (1) pressure spring bend , Or too weak, or too short (2) cone valve seat with poor sealing (such as cone valve seat wear, cone valve contact surface is not round, contact surface too wide to enter the dirt or glue stick (1) Replace the spring (2) Repair and replace the cleaning, so as to achieve the requirements (C) Suddenly increased pressure 1. Main valve failure The main spool insensitive, suddenly stuck in the closed state (such as parts machining accuracy is low, the assembly Poor quality, too much oil, etc.) overhaul, replacement of parts, filtration or replacement of oil 2. Pilot valve failure (1) Pilot valve spool and seat surface suddenly stuck, Causing a stuck (1) cleaning repair or replacement of oil (2) replacement of spring (four) a sudden drop in pressure 1. The main valve failure (1) the main spool orifice suddenly blocked (2) the main spool insensitive, Suddenly stuck in the closed state (such as parts machining accuracy is low, the assembly quality is poor, the oil is too dirty, etc.) (3) the main valve cover gasket suddenly damaged (1) cleaning, filtration or replacement of oil (2) , Filter or replace the oil (3) to replace the seal 2. Pilot valve Barrier (1) sudden rupture of pilot valve spool (2) Sudden break of pressure regulating spring (1) Replacement of spool (2) Replacement of spring (3) Failure of far port solenoid valve Suddenly electromagnet power failure, unloading relief valve check Electrical failure and eliminate (E) pressure fluctuations (unstable) 1. Main valve failure (1) the main spool movement is not flexible, and sometimes stuck phenomenon (2) (4) Damping aperture is too large, resulting in poor damping effect (1) Repair replacement parts, gland screw tightening force should be uniform (2) Open the clean, check the oil quality , Change the fluid (3) repair or replacement parts (4) appropriate to reduce the damping aperture 2 pilot valve failure (1) pressure spring bending (2) cone valve and cone valve contact bad, uneven wear (3) (1) Replace the spring (2) Repair or replace the parts (3) Tighten the lock nut after adjusting the pressure (6) Vibration and noise 1. Main valve failure The main valve plug Uneven radial force at work, resulting in unstable performance 1) The valve body and the main spool geometry accuracy is poor, the edges have burrs 2) There is dirt in the valve body to increase or uneven with the gap 1) Check the accuracy of parts, parts that do not meet the requirements should be replaced and The edge of the burr removed 2) repair replacement parts 2 pilot valve failure (1) cone valve seat contact with the poor roundness of the round surface is not good, large values ​​of roughness, resulting in pressure regulating spring imbalance, the cone The valve oscillation intensifies, resulting in scream (2) pressure regulating spring axis and the end face is not vertical enough, so the needle valve will tilt, resulting in uneven contact (3) the pressure regulating spring biased to the side of the positioning rod (4) (5) Pressure spring lateral bending (1) The oil seal surface roundness error control within 0.005 ~ 0.01mm (2) to improve the cone valve accuracy, the roughness should reach Ra0.4μm (3) to replace the spring (4) Improve the quality of the assembly (5) Replace the spring (3) Replace the spring with system (3) Air pump exists in the system. Air is sucked into the system or air is present in the system. Exhaust air is not used properly. Resistance is too high or back to the oil filter Plug or return pipe close to the bottom of the tank properly increase the diameter, reduce elbow, return pipe mouth should be twice the diameter of the tank above the bottom, replace the filter 6. Remote control port diameter improper overflow valve remote control port to the solenoid valve The diameter of the pipe between the should not be too large, the General Assembly caused by the general vibration of the tube to take more appropriate 6mm Second, the common fault and valve treatment in the following table: Analysis of the reasons for the failure to eliminate (a) no secondary pressure 1. The main valve Failure of the main spool stuck in the fully closed position (such as parts of low precision); the main valve spring break, bending deformation; blocking plugging repair, replacement parts and springs, filter or replace the oil 2. No oil to the valve Check the oil supply to eliminate the fault line (2) can not afford the role of decompression 1. The use of the wrong drain port barrier 1) screw is not unscrew open 2) drain pipe slender, elbow and more resistance 3) drain pipe and the Lord Back to the oil pipeline connected back to the oil back pressure is too large 4) Drainage channel is blocked, not through 1) unscrew the screw 2) to replace the pipe to meet the requirements 3) the drain pipe must be separate from the oil return pipe, separate back to the tank 4) Clean drain line 2. Main valve failure The main spool stuck in the fully open position (such as low precision parts, oil is too dirty, etc.) Repair, replacement parts, check the oil, replace the oil 3. Cone valve failure Pressure regulator spring is too hard, Bending and stuck moving replacement spring (C) the second pressure instability Main valve failure (1) the main spool and valve body geometry accuracy is poor, work insensitive (2) the main valve spring is too weak, deformation or the main valve Core stuck, so that the spool movement difficult (3) damping holes when blocking (1) overhaul to make it flexible (2) to replace the spring (3) cleaning damping holes (d) secondary pressure rise is not high . External leakage (1) roof with oil spill, the reasons for such as: aging seal failure, loose screws or tightening torque uneven (2) the plug at the oil leakage (1) replace the seals, tighten the screws, And ensure uniform torque (2) Tighten and eliminate leakage 2. Cone valve failure (1) Cone and seat contact poor (2) Regulating spring is too weak (1) Repair or replacement (2) Replacement Third, the sequence valve Common failures and treatment in the following table: Analysis of the causes of failure to eliminate (a) always out Oil, can not afford to sequence valves (1) the spool in the open position stuck (such as poor geometric accuracy, the gap is too small; spring bending, fracture; oil dirty) (2) check valve in the open position stuck (Such as poor geometric accuracy, the gap is too small; spring bending, fracture; oil dirty) (3) Check valve seal is poor (such as poor geometric accuracy) (4) pressure regulating spring fracture (5) 6) Without cone valve or steel ball (1) repair, to meet the requirements of the gap, and to move the spool flexible; check the oil, if not meet the requirements should be filtered or replaced; replacement spring (2) To meet the requirements and make the one-way valve spool flexible; Check the oil quality, if not meet the requirements should be filtered or replaced; Replacement spring (3) Repair, Check valve seal is good (4) Replace the spring (5) (6) refill (2) always out of oil, can not afford the role of sequence valve (1) the spool stuck in the closed position (such as poor geometric accuracy; spring bending; dirty oil) (2) (Such as damping holes blocked, or remote control pipe is squashed blocked ) (3) remote control pressure is not enough, or the bottom cover with a serious oil leakage (4) leading to the pressure regulating valve oil on the orifice is blocked (5) the drain pipe back pressure is too high, so that the slide valve can not move (6) adjust the spring is too hard, or the pressure is too high (1) repair, the slide valve flexible movement, replace the spring; filter or replace the oil (2) clean or replace the pipe, filter or replace the oil Control the pressure, tighten the end cap screws and make it even force (4) cleaning (5) drain pipe can not be connected to the oil return pipe should be individually connected back to the fuel tank (6) to replace the spring, adjust the pressure (c) The pressure value does not meet the requirements (1) regulator spring adjustment is not appropriate (2) regulator spring lateral deformation, the maximum pressure can not adjust to (3) slide valve stuck, moving difficult (1) readjust the required pressure (2) (4) vibration and noise (1) back to the oil resistance (back pressure) is too high (2) the oil temperature is too high (1) reduce the oil return resistance (2) control the oil temperature within the specified range (E) reverse one-way sequence valve can not be back to the oil check valve stuck open check one-way valve Fourth, the flow valve fault and treatment of the following table common: Failure Analysis of the reasons for the elimination of the method (a) adjust the throttle handle Flow changes 1. Pressure compensation valve does not act as a pressure compensation valve stuck in the closed position 1) spool and valve sleeve poor geometric accuracy, the gap is too small 2) the spring side bending, deformation and the spool stuck 3) spring Too weak 1) check the accuracy, repair gap to meet the requirements of mobile and flexible 2) replace the spring 3) replace the spring 2 throttle fault (1) oil is too dirty, the throttle blocked (2) handle and throttle spool Improper assembly position (3) Throttle valve spool connection is missing or not installed (4) Throttle valve spool due to the gap is too small or deformed and stuck (5) Throttle thread is blocked by dirt, resulting in Poor regulation (1) check the oil, oil filter (2) check the reasons, reassembly (3) replace the key or refill button (4) cleaning, repair clearance or replacement parts (5) Oil valve spool is not reversed to check the original And eliminate (b) the actuator speed instability (flow instability) 1. Pressure compensation valve failure (1) pressure compensating valve spool insecure 1) the spool stuck phenomenon 2) compensation valve damping orifice 3) The spring is laterally bent, deformed, or the spring end is not perpendicular to the spring axis. (2) The pressure compensating valve spool is stuck in the fully open position. 1) The compensating valve is blocked by the orifice. 2) The spool and the valve Set of geometric accuracy is poor, with the gap is too small 3) the spring side bending, deformation and the spool stuck 1) repair, to move flexible 2) clean the orifice, if the oil should be replaced 3) replacement of spring 1) cleaning Damping hole, if the oil is too dirty, should be replaced 2) Repair to achieve mobile and flexible 3) Replace the spring 2. Throttle valve fault (1) Throttle plot of dirt, resulting in blockage when the pass (2) Flow changes outside the valve will cause flow changes (1) Open the clean, check the oil, if the oil should be replaced by substandard (2) changes in external load or require a very smooth movement of the actuator speed system should be used instead Speed ​​valve 3 oil quality is poor (1) The oil temperature is too high, resulting in a change of flow through the restrictor. (2) The compensating rod of the flow control valve with temperature compensation is poorly sensitive and damaged. (3) Oil is too dirty, blocking orifice or orifice (1) Check the cause of temperature rise, reduce the oil temperature, and control within the required range (2) Select the temperature-sensitive material to compensate rod, bad should be replaced (3) Clean, check the oil, Replacement 4. Check Valve Malfunction In the flow control valve with check valve, check valve is not good sealing lap check valve to improve the sealing 5. Pipeline vibration (1) air in the system (2) due to Pipeline vibration to adjust the position of the change (1) should be air purged (2) after adjustment with a locking device to lock 6 leak leakage and leakage to flow instability, resulting in uneven execution of the work element speed elimination Leakage, or replacement of components Fifth, the common fault of the directional valve and deal with the following table: 1, the common fault valve and handle the fault phenomenon analysis and elimination methods (A) the main valve does not exercise 1 electromagnet fault (1) solenoid coil Burn out (2) electromagnet Lack of power or magnetic flux leakage (3) electrical circuit failure (4) electromagnet without control signal (5) electromagnet iron core stuck (1) check the reasons for repair or replacement (2) check the reasons for repair or Replacement (3) Eliminate the fault (4) Check the control signal (5) Check or replace 2. Pilot solenoid valve fault (1) The valve core and the valve hole stuck (such as poor parts geometry; (2) spring side bend, so that the slide valve stuck (1) repair with the gap to meet the requirements of the spool movement flexibility; filter or replace the oil (2) replace the spring 3. The main valve (1) poor accuracy of the valve body and the valve body (2) spool and the valve hole with too tight (3) there is a burr on the spool surface (1) repair with the research gap to meet the requirements (2) (3) deburring, rinsing 4 hydraulic control circuit failure (1) control circuit oil-free 1) control circuit solenoid valve is not reversed 2) the control circuit is blocked (2) the control circuit pressure is less than 1) Leakage at the valve cover 2) The throttle valve on the side of the drain chamber is too small or blocked (2) 1) Tighten the cover screws 2) Clean the throttle and adjust the appropriate 5. Oil deterioration or the oil temperature is too high (1) Check the cause and eliminate 2) Check the cleaning, 1) the oil is too dirty to make the valve core stuck (2) the oil temperature is too high, so that the parts have thermal deformation, resulting in stuck phenomenon (3) the oil temperature is too high, the oil gel, stick to the spool Stuck (4) the oil viscosity is too high, the spool movement difficult and stuck (1) filter or replace (2) check the cause of the oil temperature is too high and eliminate (3) clean, remove the oil temperature is too high (4) replacement Suitable fluid 6. Poor installation Deformation of the valve body 1) Uneven tightening torque of the mounting screw 2) "Unpredictable" connection of the valve body 1) Tighten the screw again and apply a force to it. 2) Reinstall the valve. Return spring does not meet the requirements (1) the spring force is too large (2) spring bending deformation, causing the valve core stuck (3) the spring break can not reset Replace the appropriate spring (b) valve flow through the valve after the lack of flow Insufficient quantity (1) Solenoids in the solenoid valve is too short (2) The geometric accuracy of the valve plug and the valve body is poor, (3) The spring is too weak, the thrust is not enough to make the spool stroke is not in place (1) Replace the suitable length of the push rod (2) With the research to meet the requirements (3) Replacement Suitable for the spring (C) pressure drop too large Valve parameters improper selection Actual flow through the rated flow rate should be used within the rated range (D) of the hydraulic control valve spool commutation speed is not easy to adjust Adjustable device failure (1) one-way Poor sealing of the valve (2) Poor machining accuracy of the throttle valve, the minimum flow rate can not be adjusted (3) Oil leakage at the valve cover of the drain chamber (4) Poor regulation performance of the needle throttle valve (1) Repair or replacement Replace (3) replace the seal, tighten the screw (4) switch to triangular slot throttle valve (5) electromagnet overheating or coil burnout 1 electromagnet failure (1) coil insulation is not good (2) electromagnet iron core (3) The voltage is too low or unstable (1) Replacement (2) Replacement (3) The change of voltage should be within 10% of the rated voltage. 2. Change of load (1) 2) to the flow exceeds the specified (3) back to the oil pressure back (1) Reduce the pressure (2) Replace the electro-hydraulic directional control valve with the proper specifications (3) Adjust the back pressure so as to be within the specified value. 3. Poor assembly Poor electromagnet core and spool axial misfit Reassemble Good coaxiality (six) electromagnet suction is not enough bad assembly (1) putt is too long (2) electromagnet iron core contact surface is not flat or bad contact (1) grinding rod to the appropriate length (2) Reassembly to meet the requirements (7) Impact and vibration 1. Commutation impact (1) large diameter solenoid valve, due to large size electromagnet, suction speed and impact (2) hydraulic valve, due to control flow Large, spool moving too fast and impact (3) one-way throttle check valve ball leakage or ball crushing, can not afford the damping effect (1) need to use large-diameter valve, should Preferentially use electro-hydraulic reversing valve (2) Adjust throttle valve orifice to slow spool moving speed (3) Repair one-way throttle valve 2. Vibration Fix electromagnet screw Loosen set screw and add washer 2, multi-way valve fault and failure to deal with the common phenomenon Reason analysis and elimination methods (a) pressure fluctuations and noise relief valve spring side bend or too soft relief valve clogging the check valve check valve closed stingy valve seat and poor contact with poor replacement of spring cleaning, the passage of the smooth repair or replacement adjustment Or replacement (B) the valve stem movement is not flexible Reset spring and limit spring damage Damage to the shaft by the elastic ring Dust seal tight Replace the damaged spring Replace the elastic ring Replace the dust seal (C) Leak cone valve and valve Poor contact with the seat screw is not fastened to adjust or replace the fastening 3, the liquid-controlled one-way valve failure and troubleshooting the reasons Analysis and elimination methods (a) the opposite direction is not sealed Leak check valve is not sealed (1) Check valve in the fully open position stuck 1) The spool and the valve hole with tight 2) The spring side bending, deformation, too weak (2) One-way valve cone and seat cone contact uneven 1) The spool Cone and valve seat concentricity difference 2) spool outer diameter and conical surface is not the same heart 3) outer diameter of the cone and the cone heart 4) fluid is too dirty (1) 1) to make the valve spool flexible 2 Change the spring (2) 1 Overhaul or replacement 2) overhaul or replacement 3) overhaul or replacement 4) filter oil or replacement (2) reverse can not open the check valve can not open (1) control the pressure is too low (2) Serious or pipe bending, squashed to make the oil is not smooth (3) Control valve stuck (such as machining accuracy is low, the oil is too dirty) (4) Control valve cover leakage (5) Check valve stuck (Such as spring bending; check valve machining accuracy is low; oil is too dirty) (1) increase the control pressure to achieve the required value (2) fastening joints to eliminate oil spills or replace the pipe (3) (4) Tighten the end cap screws and ensure uniform tightening torque (5) Cleaning, repair, so that the spool movement flexibility; replacement of spring; filter or replace the oil 4, the pressure relay (pressure switch) common faults and (1) no output signal (1) microswitch is damaged (2) electrical circuit fault (3) spool jammed or blocked orifice (4) inlet pipe bending, deformation, so that the oil Fluid flow is not smooth (5) Adjust the spring Hard or pressure is too high (6) contact with the micro switch is not adjusted (7) spring and ejector assembly is poor, there are signs of stagnation (1) replace the micro switch (2) check the reasons Fault (3) cleaning, repair, to meet the requirements (4) to replace the tube, so that the flow of oil flow (5) to replace the appropriate spring or adjust the pressure value as required (6) carefully adjusted to make good contact with the contacts , So that the action is sensitive (b) poor sensitivity (1) mandrel column pin friction is too large, or ball and plunger contact friction is too large (2) poor assembly, the action is not flexible or "Do not force" ( 3) Micro switch contact stroke is too long (4) Adjusting screws, ejector pins and other improper adjustment (5) The ball is not round (6) Valve core movement is not flexible (7) Improper installation, such as uneven tilt installation (1) (2) reassembled so that the action is sensitive (3) reasonable position adjustment (4) a reasonable adjustment of screw and plunger position (5) ball replacement (6) cleaning and repairing to achieve flexibility (7) Vertical or horizontal installation (C) Signaling too fast (1) into (2) The diaphragm is fragmented (3) The impact pressure of the system is too large (4) The design of the electrical system is not correct (1) The orifice is appropriately reduced or the damping pipe (serpentine pipe) (2) replace the diaphragm (3) in the control pipe additional damping tube to reduce the impact pressure (4) according to process requirements of the design of electrical systems

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