Electro-Hydraulic Servo Valve Repair Workflow

Electro-hydraulic servo valves are the most critical components in hydraulic systems. Though relatively small in size, they play a vital role in product performance. A systematic repair workflow ensures quality and reliability.

I. Initial Inspection & Diagnosis

1. Visual inspection for external damage, corrosion, or contamination
2. Electrical testing of coil resistance and insulation
3. Performance benchmarking on test stand to identify deviations
4. Documentation of initial condition and customer requirements

II. Disassembly & Cleaning

1. Complete disassembly in a clean room environment (ISO Class 7 or better)
2. Ultrasonic cleaning of all components using approved solvents
3. Inspection of spool, sleeve, nozzle, and flapper under microscope
4. Assessment of wear patterns and identification of root cause failures

III. Repair & Replacement

1. Replacement of all seals, O-rings, and filter elements
2. Machining or replacement of worn spools, sleeves, and bushings
3. Nozzle and flapper restoration or replacement
4. Torque motor re-magnetization and calibration
5. Feedback element (LVDT) testing and replacement if necessary

IV. Reassembly & Calibration

1. Reassembly under clean room conditions with proper torque specifications
2. Null adjustment and mechanical zero setting
3. Electrical null and gain calibration
4. Spool position feedback verification

V. Testing & Quality Assurance

1. Static performance testing: flow vs. input signal curve
2. Dynamic performance testing: frequency response and step response
3. Pressure gain and leakage testing
4. 24-hour burn-in test under rated conditions
5. Final performance report generation and comparison with OEM specifications

VI. Packaging & Delivery

1. Protective packaging with desiccant and anti-corrosion treatment
2. Service ports sealed with clean plugs
3. Test report and warranty documentation included
4. Shipping in shock-absorbing container

FOCH follows strict ISO 9001 quality management procedures throughout the repair process, ensuring every serviced servo valve meets or exceeds original performance specifications.