Potential Trouble
Servovalve does not follow input command
signal. (Actuator or components are
stationary or creeping slowly).
High threshold. (Jerky, possible oscillatory
or "hunting" motion in closed loop system).
Poor response. (Servovalve output lags
electrical command signal).
High Null Bias, (High input current required
to maintain hydraulic cylinder or motor
stationary).
Probable Cause
1. Plugged inlet filter element.
1. Plugged filter element.
1. Partially plugged filter element.
1. Incorrect null adjustment.
2. Partially plugged filter element.
Remedy
1. Replace filter element.
1. Replace filter element.
1. Replace filter element.
Check for dirty hydraulic fluid in system.
1. Readjust null.
2. Replace filter element and check for dirty
hydraulic fluid in system.
7.TROUBLESHOOTING CHART
The following troubleshooting chart list potential troubles encountered, probable causes, and remedies.
8. FILTER ASSEMBLY REPLACEMENT
a. Remove the four socket head capscrews and lockwashers with 3mm Allen
wrench.
b. Remove the filter retainer.
c. Remove and discard the filter disk.
d. Remove and replace the O-Ring on the filter retainer and the O-Ring in
the filter bore.
e. Reinstall in reverse order, torque screws to 35-40 in-lbs.
9. FUNCTIONAL CHECKOUT AND CENTERING
a. Install servovalve on hydraulic system or test fixture, but do not connect
electrical lead.
b. Apply required system pressure to servovalve and visually examine for evi-
dence of external leakage. If leakage is present and cannot be rectified by
replacing O-Rings, remove the discrepant component and return for
repair or replacement.
Note: If the system components are drifting or hardover, adjust
the mechanical null of the servovalve.
c. Connect electrical lead to servovalve and check phasing in accordance
with system requirements.
10. AUTHORIZED REPAIR FACILITIES
Moog does not authorize any facilities other than Moog or Moog subsidiaries to
repair its servovalves. It is recommended you contact Moog at (716)655-3000
to locate your closest Moog repair facility. Repair by an independent
(unauthorized) repair house will result in voiding the Moog warranty and could
lead to performance degradation or safety problems.
Figure 3
Socket Head
Cap Screw
2X O-Ring
P/N 42082-3
Filter Retainer
Filter
P/N A67999-65
Tools and Equipment
a. 3mm Allen wrench
b. Torque wrench
2X O-Ring P/N G2141-13-15
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