Moog D633-A Series, User Manual

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11 Service Troubleshooting
© Moog GmbH User Manual "D633-A Series" (CA80942-001; Version 1.0, 12/08) 59
11.3 Troubleshooting
Possible faults
The following faults may occur:
• Leak at the valve connecting surface
Ö Chapter "11.3.1.1 Leak at the valve connecting surface", page 59
• Leak at the linear force motor screw plug
Ö
Chapter "11.3.1.2 Leak at the linear force motor screw plug", page 59
• No hydraulic response by the valve
Ö Chapter "11.3.2 No hydraulic response by the valve", page 60
• Instability of the external control loop
Ö
Chapter "11.3.3 Instability of the external control loop", page 60
Restarting after correcting
the fault
After correcting the fault, if necessary remount and restart the valve.
Ö Chapter "7.3 Mounting the valves", page 38
Ö Chapter "3.2.2 Restarting the valve", page 15
11.3.1 Leaks
11.3.1.1 Leak at the valve connecting surface
Leak at the valve
connecting surface
Measures:
• Check for presence, elasticity, integrity and correct seating of the O-rings
in the valve ports (A, B, P, T, etc.).
If necessary, install O-rings, replace or correct the seating.
• Check the valve’s mounting and connecting surfaces, the valve and the
hydraulic system for damage, contamination and evenness.
• Check installation screws for secure and correct seating.
Retighten screws if necessary with the torque wrench for WAF 4 hexagon
socket head cap screws.
Tightening torque of installation screws: 6.8 Nm (5.0 lbf ft) ± 10 %
11.3.1.2 Leak at the linear force motor screw plug
Leak at the linear force
motor screw plug
Measures:
• Check ports P and T for correct connection.
• Check max. pressure in ports T and Y.
The return pressure in T may exceed 50 bar (725 psi) only if port Y is
used.
If the fault cannot be corrected by means of the measures set out below,
please contact us or one of our authorized service centers.
WARNING In the event of a leak at the linear force motor screw plug,
have the valve checked by us or one of our authorized ser-
vice centers.