11 Service
Troubleshooting
© Moog GmbH User Manual "D633-A Series" (CA80942-001; Version 1.0, 12/08) 60
11.3.2 No hydraulic response by the valve
No hydraulic response by
the valve
Measures:
• Check whether all the machine components, connections and ports con-
form to the specifications of the machine manufacturer and operator.
To do so, on the valves compare the data on the nameplate with the spec-
ifications.
• Check whether the hydraulic installation is correct and whether all the hy-
draulic ports are correctly established.
• Check whether the hydraulic pressure is present.
• Check whether the connector is correctly attached and non-corroded.
• Check whether there is a command signal failure or a faulty electric cable.
• Check whether the desired command signal is applied at the connector.
• Check whether the valve is in the fault state.
If necessary, correct the fault and then restart the valve by switching the
command signal off and then on again.
Typical fault causes:
– Control error (e.g., due to the spool sticking, which can be caused for
instance by contamination)
– No command signal (e.g., due to open circuit)
11.3.3 Instability of the external control loop
Instability of the external
control loop
Measures:
• Check whether the external control loop is stable.
If necessary, reduce control loop gain.
• Check whether the signal quality of the command signal is sufficient.
• Check whether the system pressure is stable.
• Check whether the quality and cleanliness level of the hydraulic fluid used
conforms to the specifications of the manufacturer and the operator of the
machine.
• Check whether the controlled system was modified.
WARNING
Touching electrically live parts exposes the user/operator
to the risk of:
• Electric shock
• Uncontrolled sequences of motions
• Destruction
• Malfunction
Touching electrically live parts must therefore be avoided!
