Basic Clean and Calibrate Process For Star Hydraulics Servovalves

Incoming Pre-Test, Disassembly and Visual Inspection

Incoming Hydraulic Parameters Checked on Servovalve Test Stand

  • Internal piston / sleeve leakage and Lap Condition
  • Check for any Feedback Ball to Spool Wear - (Glitches)
  • Hysteresis
  • Null Shift
  • Symmetry
  • Threshold
  • Valve Polarity
  • Linearity
  • Rated Flow

Visual Inspection of Parts - Complete Disassembly of Second Stage

  • Contamination Level and Type
  • Seal Material and Condition of Seals
  • Internal Filter(s) Condition
  • Visual Feedback Ball for Wear Spots and Measure Feedback Ball
  • Coil Resistance
  • Internal Orifice Condition and Filter sealing area.(Check for wear under 200X Microscope)
  • Electrical Solder Joints and Wire Condition
  • Surfaces Checked For Any Scoring or Deep Scratches

The Torque Motor is Mounted on a Test Fixture to check for:

  • Check First Stage (Torque Motor) Control Pressure (Nozzle to Flapper Gap)- To Ensure Proper Hydraulic Amplification.
  • Condition of Flapper Area on A.F.S.A. and Nozzle Seal Off
  • Torque Motor Balance
  • Check Magnets and Air Gap Dimension and Condition

NOTE: Processes and parts needed beyond a C&C will be priced and added to quote at this point.
After the Repair price is approved by the Customer we will proceed with the repair.

Rework and Clean Parts

  • Parts Soaked in Solvent and Cleaned - with the exception of Electrical Torque Motor Parts
  • Ultrasonically Clean Parts - Where applicable
  • Demagnetize Parts Where Required
  • Lap I.D. of Bushing and O.D. of Spool

Reassembly of Servovalve:

  • Replace Seals with appropriate compound and durometer
  • Reassemble the servovalve according to Manufactures procedures and specifications
  • Replace any defective parts Listed on Quote sent to Customer

Final Test (Test Equipment Calibrated and Traceable to NIST Standards)

The servovalve is final tested hydraulically and at this time the Torque Motor is realigned to the valve’s second stage to ensure that the drive pressure is set equally to the ends of the spool. After the servovalve has met all of the test specifications your valve will be sent back to you accompanied by a Performance Certification. On one side it will have a detailed listing of what was found on our incoming inspection and any corrective actions we took to repair the valve. On the other side it will show a graph, plotted with a X-Y recorder comparing input current vs. output flow.