Maintenance method of 4WE6 high pressure solenoid reversing valve

Maintenance method of 4WE6 high pressure solenoid reversing valve

The 4WE6 series high-pressure solenoid directional valve (such as REXROTH, HYDAC and other brand products) is the core direction control component in the hydraulic system. It is driven by a direct-acting wet electromagnet, with a working pressure of up to 315bar and a maximum flow rate of 80L/min. Because it operates under high pressure and high frequency conditions for a long time, scientific and standardized maintenance is the key to ensuring the life of the valve body and system stability. The following introduces the system from four dimensions: daily maintenance, regular inspection, common fault handling and precautions.

1. Routine maintenance: nip problems in the bud

1. Oil management – ​​lifeline

Cleanliness is the core indicator: it is recommended that the cleanliness of the system hydraulic oil be maintained at NAS 1638 ≤ level 7, the filtration precision ≤ 10 μm, and the filter element should be replaced regularly (it is recommended to replace it every 2000 working hours or when the pressure difference alarm is activated).

It is strictly forbidden to allow moisture, dust, metal shavings and other contaminants to enter the system. These are the primary culprits that cause valve core sticking and seal wear. A high-pressure filter must be installed in front of the valve (βx≥200 recommended).

It is recommended that the viscosity of hydraulic oil be controlled below 20CST. Too high a viscosity will lead to slow commutation and increased internal leakage.

2. Electrical system inspection - once a week

Check project specific requirements

The fluctuation range of the supply voltage DC24V model is ±10% of the rated voltage, and the AC model is +15%~-10%. Exceeding the range will cause overheating of the coil or poor suction.

Use a multimeter to measure the coil resistance and compare it with the manufacturer"s nominal value; if the resistance is 0 (short circuit) or infinite (open circuit), the coil must be replaced immediately

Check the wiring terminals for looseness, oxidation or water ingress. Loose terminals are a common cause of "valve not reversing".

Observe the appearance of the coil for discoloration, bulging, or a burnt smell. The surface temperature of the NZ5L coil can reach 85°C under continuous power supply. Ensure good heat dissipation.

3. Appearance and leakage inspection - once a day

External leakage inspection: focus on checking whether there is oil leakage at the joint surface of the valve body and the mounting plate, the end cover screws, and the joint between the solenoid and the valve body. If leakage is found, tighten the bolts first. If it fails, replace the O-ring.

Judgment of internal leakage: Observe whether the actuator (cylinder) appears to be slow in movement, drifting in the parking position, unable to maintain pressure, etc. This is a typical signal of internal leakage.

Abnormal sound monitoring: "clicking" noises during reversal and excessive buzzing of the electromagnet may indicate stuck valve core, spring fatigue or loose installation.

4. Manual emergency function test - once a month

The 4WE6 valve has a manual emergency button, which should be pressed and tested regularly to confirm that the valve core can change direction normally when the power is off. This is your first line of defense to keep your device safe.

2. Regular maintenance: Recommended once every 6 to 12 months

High-frequency action situations (such as injection molding machines, engineering machinery) should be shortened to 3 to 6 months.

Maintenance process (operating under pressure is strictly prohibited!)

Step one: Preparation before disassembly

Cut off the power → release the system pressure → clean the outside of the valve body (to prevent dirt from entering the system during disassembly)

Step 2: Disassemble in order (refer to manufacturer’s drawings)

End cover → spring → valve core → seal

Step Three: Key Inspections

Component Inspection Content Judgment Criteria

Whether there are scratches, rust, or burrs on the surface of the valve core. Slight scratches can be polished; serious strains must replace the valve core or the entire valve body.

If the inner wall of the valve hole is worn or strained and the fit clearance is out of tolerance, replace the valve body.

Whether the return spring is broken, deformed, or fatigued and the elastic force is reduced, causing the reversal to be insufficient and must be replaced.

The degree of aging of all seals, O-rings, back-up rings, and combined seals is recommended for each maintenance. Do not reuse old seals.

Whether the solenoid push rod is bent or worn affects the valve core thrust and needs to be replaced.

Step 4: Cleaning (key!)

Use special cleaning agent or kerosene to clean all parts. It is strictly prohibited to use cotton yarn (fiber residue will cause secondary pollution)

Blow dry all oil passages and mating surfaces with compressed air to ensure there is no residual liquid

Step 5: Assembly

Apply the same hydraulic oil of the system to the valve core and seals for lubrication.

Tighten the end cover screws diagonally evenly and use the specified torque to prevent the valve core from being stuck due to deflection.

The coil can be rotated and installed 360°. If you need to replace the coil online (supported by some models), there is no need to disassemble the hydraulic pipeline and no oil leakage.

3. Common faults and solutions

Possible causes and solutions for malfunctions

The valve does not reverse, the solenoid is burnt, the valve core is stuck, the voltage is insufficient, check/replace the coil, clean the valve core, and confirm the power supply voltage.

Slow reversing, oil contamination, spring fatigue, internal leakage. Replace the hydraulic oil, flush the system, and replace the springs.

Large internal leakage. The sealing ring is aging and the valve core is worn. Replace the seal or valve core assembly.

If the external leakage end cover is loose or the O-ring is damaged, retighten it or replace the sealing ring.

Loud noise/vibration, hydraulic shock, too high back pressure, loose installation, install buffer valve, check oil return back pressure, tighten installation bolts

There is sound when power is turned on but the direction does not change. The fluid is over-pressured, impurities are stuck in the valve, and the pressure difference is insufficient. Reduce the working pressure. Disassemble, clean and install a filter.

The spring does not reset after power failure, the valve core is stuck, and the oil viscosity is too high. Replace the spring, clean the valve core, and replace the adapted hydraulic oil.

Coil overheating, voltage is too high/low, long-term electrification, poor heat dissipation. Adjust voltage, avoid long-term electrification, and install heat dissipation measures.

4. Precautions for installation and use

Installation direction: The arrow on the valve body should be consistent with the flow direction of the medium. The electromagnet should be installed vertically upward and cannot be installed in a place with direct dripping or splashing water.

Installation surface requirements: The flatness of the installation plate is ≤0.01mm, and the surface roughness Ra is ≤1.6μm. Otherwise, uneven compression of the O-ring will lead to micro leakage.

Before starting the system: run without load first, energize it several times to allow the solenoid valve to adapt to the temperature before officially putting it into use; remove the air from the system.

Avoid long-term neutral blockage: If the central closed valve is in the intermediate transition position for a long time, it will accelerate wear.

Bypass protection: When the solenoid valve fails or is cleaned, a bypass device should be installed to ensure that the system continues to operate.

Storage backup valve: Seal all oil ports, place in a dry environment, and energize regularly to prevent moisture.

Explosion-proof occasions: Products with corresponding explosion-proof levels must be selected, and maintenance and repairs must be performed by qualified professionals.