Frequently asked questions and answers-steering gear systems of ships



    What are the types of steering systems?

    An electro-hydraulic steering gear system
    Ram type system (2 or 4 ram) and Vane type system
    An all-electric steering gear system
    Ward Leonard system and Single motor system

    What is hunting gear?

    Hunting gear is acting as a feedback mechanism. Hunting gear transmits the position of the rudder to the p/p control lever by the floating lever

    What are the safety devices for the steering system?

    ELECTRICAL
    • The motor should able to carry 200% of full load current
    • 200% of motor insulation
    • Overload alarm
    • Phase failure alarm
    • Power failure alarm
    • Short circuit trip
    • One motor should be connected to ESB
    • Should start zero time delay after power failure recovered
    MECHANICAL
    • Hydraulic tank low-level alarm
    • Hydraulic tank low-low level trip-safematic
    • Hydraulic oil temperature high alarm
    • Filter clogged alarm
    • Hydraulic lock alarm
    • Angle adjusting stopper (limit switch at PORT & STBD side)
    • Relief valve

    What is the indication of air in the steering system?

    • Jerky movement
    • Jumping pressure gauges on the system
    • Defective steering operation

    What is the effect of air within the steering system?

    It is lead to incorrect balance between units, time lags and irregular operation

    Steering gear maintenance

    Before departure
    • Checks carried out as per checklist
    • Visual inspection
    • Checking the function of the steering gear
    • Check safety equipment and make sure the all alarms are functioning properly
    • Actual rudder angle and indicator
    • Communication system
    Daily
    • Visual inspection: deformations, cracks, missing mechanical connectors, defective mechanical or electrical connections
    • Motor load current and temperature
    • Check for unusual noises
    • Visual inspection for leaks in the hydraulic system
    • Check oil level on the oil expansion tank
    • Greasing
    Weekly
    • Check oil level on the oil storage tank
    • If steering gear equipped with safematic system: check that safematic is functioning properly
    • Visual inspection of automatic grease lubricator and hoses
    Every 3 months interval
    • As per manufacturer information
    • Thorough inspection: deformations, cracks, missing mechanical connectors, defective mechanical or electrical connections
    • Limit switch operation
    • Emergency steering gear drill.
    • What is the purpose of buffer spring?
    • Buffer spring used to protect the control system from the damages.

    Ward Leonard system

    This is an electrical type steering gear system. Ward Leonard system controls the speed of DC (direct current) motor from zero to maximum in either direction.

    What is the hydraulic lock?

    In this situation, the rudder is not responding to the command

    What are the reasons for the hydraulic lock?

    • The air into the system
    • Hydraulic oil dirty renew hydraulic oil
    • Synchro transmitter or receiver malfunctioning
    • Sluggish movement of the rudder
    • Very frequent movement
    • Limit switch malfunctioning
    • Main pump malfunction
    • Rudder angle having the error
    • Hydraulic lock alarm unit malfunctioning or defective

    How to recover the system from the hydraulic lock?

    • Take control to local
    • Purging out the air If air in the system
    • Check the Synchro system
    • Check the limit switch operation
    • Check the rudder movement for proper operation

    How to try out hydraulic lock alarm?

    • Take control to local
    • Press both solenoid at the same time
    • Both limit switches activate at the same time

    The steering gear is not responding to the command what will be the reasons?

    • Steering Angle Indicator faulty.
    • Solenoid not working
    • Oil level low
    • The switch is in Manual
    • PI Controller faulty


    What is the significance of 200% insulation in steering gear motor?

    It means that motor winding can withstand 200% of FLC

    What are the FU and NFU mode?

    FU - follow up
    • FU has two modes
    • Auto and manual
    • Auto - autopilot command
    • Manual - hand steering and once u give a command like 10-degree port then rudder go to 10-degree port then it comes to midship

    NFU - no follow-up
    • NFU mode in simple words emergency steering from the bridge
    • All controls bypassed
    • In this rudder will not come to Midship once u give the command

    Critical spares for steering gear?

    • Synchro transmitter and receiver
    • PID controller
    • Steering gear motor and its control ckt spares (contactors, breakers)
    • Limit switches
    • Proximity switches
    • Rudder angle indicator etc.

    Why is time delay in when starting a steering gear motor?

    2-sec delay because servo pump start in prior to the main pump


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    3 Comments

    1. Though most of you must be aware as an ETO / Marine Engineer --- the Steering Gear Motor Rotors are supported on the Motor End Covers on 3 Ball Bearings and not on 2 ball bearings as rest of the motors on board ship. Please answer about arrangement of these 3-ball bearings on the rotor. Why?
      Dr Mukesh Kumar
      Ex-ETO
      BSM
      MUKESH63.K@GMAIL.COM

      ReplyDelete
    2. Thanks for your work. Very educative

      ReplyDelete

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