Which are most common Steering Gear faults and appropriate actions?
09 Jun '17, 00:44
Steering Gear troubleshooting guidelines
1) Hydraulic or pump or it's electric motor failure.
a) Can not be operated from the bridge in any mode
b) "OVERLOAD" or "NO VOLTAGE" Steering Gear alarms
a) Start the standby pump.
b) Disconnect the electrical power to the failed pump and hang a warning sign.
c) Inspect fuses, wiring and magnetic contactor for damage, electric motor (bearings, insulation and resistance test), pump for seizure and mechanical damage
2) Autopilot failure.
SIGNS: There is no control of the Steering Gear in autopilot mode.
a) Change over to FU, NFU or emergency steering whichever is operational
b) Investigate and identify faulty unit or communication line: servo board at the local control, rudder angle transmitter, main autopilot unit on the bridge. Check for faulty fuses, broken or loosen wire terminals first as they suffer most because of vibration
3) Steering control lost in all modes from the bridge (Even after switching to another unit).
a) Immediately change over to Emergency steering mode
b) Investigate communication line from the bridge control unit to local servo control board
4) Hydraulic pipelines or connections leaking.
a) Change over to stand-by hydraulic unit/pump
b) Lock out faulty unit disconnect it on the switchboard and hang a warning sign.
c) Reduce of ship’s speed may be required.
d) Isolate and eliminate the leakage.
e) Fill the system with oil and vent the air.
f) Restore system valves layout and test the unit.
5) Excessive noise.
The probable cause is the presence of air in the oil.
ACTION: Release air through vent valves on the steering gear and pumps.
6) Excessive temperature.
CAUSES: Closing the valve on the oil tank or lack of oil in it.
ACTION: Check the position of the valve on the tank and fully open it.
The oil tank must be filled to 75% of its capacity.
7) Steering gear hunting, vessel is yawing on the course.
a) Servo board improperly adjusted (rudder feedback and dead band control potentiometers).
b) Excessive play and wear or geometry distortion of rudder feedback mechanical linkages.
c) Internal steering gear or hydraulic cylinder leakages. F.e. faulty counterbalance valves, hydraulic cylinder piston seal etc.
a) Check/adjust feedback linkages.
b) Check/adjust rudder angle transmitter. c) Check/adjust counterbalance valves.
d) Check/adjust servo board settings.
8) Rudder angle different from setpoint.
a) Excessive play and wear or geometry distortion of rudder feedback mechanical linkages.
b) Steering Gear needs rudder position calibration.
a) Check/adjust feedback linkages.
b) Check/adjust rudder angle transmitter.
b) Calibrate rudder position indication and feedback signals.
9) When setting the angle of the rudder, the rudder moves to the limiter.
Rudder feedback or limit switch signal failure.
Check/adjust rudder feedback transmitter and limit switches.
10) Rudder speed low.
a) Internal leakages in relief or by-pass valves.
b) Internal leakages in hydraulic pump.
a )Check/replace hydraulic system components.
b) Overhaul hydraulic pump.
11) Rudder angle change by the influence of wave with stopped steering gear.
Internal leakages in counterbalance, relief or by-pass valves.
Check/replace hydraulic system components.
12) The rudder is shifted by jerks.
Air in the system.
Vent the air.
13) Low hydraulic pressure.
a) Dirty filters. b) Faulty relief valve.
c) Pump worn.
a) Change over to standby unit.
b) Clean filters.
c) Inspect/replace relief valve.
d) Inspect/replace/overhaul hydraulic pump.
14) Hydraulic pump has excessive noise and vibration.
a) Air in the system.
b) Wear of pump bearings or plungers.
a) Vent the air.
b) Overhaul/replace the pump.
09 Jun '17, 00:55