Steering Gear Flashcards
Describe the procedure for using the local, emergency steering positions, should the bridge control
system become inoperative?
- Establish clear communication with the bridge
- Take local control
- Ensure that we have an operating compass reading or the bridge can read it out.
- Prove you have control and the heading matches that for the bridge
- Make sure you are in a safe environment
- Initial commands made at low speed through the water
If underway on a long passage make sure you have a schedule so you can be relieved by a
competent person
7. - Need an additional person awake to keep watch on the running of the engine room.
Communication can be via the radio on a separate channel to the crew or via a direct plug in.
Actuation can be push button which acts on a solenoid control block, or manual buttons on the
solenoid block or even manual steering wheel.
With reference to an electro-hydraulic steering gear explain:
How steering can be achieved should there be total failure of the hydraulic system?
There are different methods depending on the type of steering system that is installed
onboard. If the hydraulic failure is due to the pump and the seals are fine for the rotary
vane/cylinders then it may be possible to connect a hand pump/additional high pressure
pump to actuate the rudder.
Only small movements would be possible using this method and using isolation valves to lock
the rudder into place.
If the engine is twin screw, by locking the rudder into a zero position, it would be possible to
steer with the engines power.
Another method is using dedicated high rated chain block assembly to specific attachments…
Not very common.
With reference to steering gears explain
100% redundancy
Single failure Criteria
a) 100% redundancy
That any part of the system can fail the operation of the steering gear is still possible, whether
this is a rotary vane, 2 ram or a 4 ram system. By opening and closing certain valves, either of
the pumps and any of the rams can be used.
b) Single failure Criteria
SOLAS states that a auxiliary steering gear doesn’t need to be fitted when the main steering
gear as two or more identical power units and is arranged such a single failure in the piping or
power units, steering can be maintained.
With reference to two ram steering gears which incorporate spherical bearings
Explain why spherical bearings are required on the ram ends?
To cater for the angular movement of the rudder. Traditionally this was done with the Rapson
slide. As the tiller moves the cylinders will pitch about there anchor slightly.
Describe all the necessary checks for the steering gear before a vessel leaves port as stated in
SOLAS?
- Completed by a competent crew member within 12 hours or leaving
- Communication method tested
- Main Steering gear (from all locations)
- Auxiliary Steering gear (from all locations)
- Remote steering gear
- Emergency power supply
- Rudder angle indicators
Describe all the necessary checks for the steering gear before a vessel leaves port as stated in
SOLAS - Rudder angle indicators
- Remote steering control system alarms
- Steering gear power unit failure alarms
- Automatic isolating arrangements & Other equipment
- Full visual inspection
- Timing requirements
State the rudder movement required by SOLAS?
The primary steering gear must be capable of rotating the rudder from 35 degrees to 30 degrees
within 28 seconds
Aux steering gear 15 degrees to 15 degrees within 60 seconds
Explain how it is ensured that the maximum movement is not exceeded in an electro-hydraulic ram
type steering gear? And a Rotary vane type gear?
With both electrical and mechanical stops. The electrically limited by a proximity switch which will
stop the hydraulic system from traveling further. 35 degrees
Mechanical limit switches which will be welded to the bed plate and prevent the ram from
bottoming out and causing damage. The electrical limit switch should prevent this from happening.
Explain how steering gear system is protected should the maximum movement be exceeded?
Overpressure relief valves to bleed off the pressure when the working pressure of the system gets
too high.
With reference to a hydraulic-hydraulic steering gear
purpose of hunting gear
Purpose of the hunting gear is to reduce the stroke of the hydraulic pump back to an idle state
when the steering gear has reached the desired angle.
Describe two methods to prevent a variable displacement pump of motoring which is used in a
steering gear?
In closed loop variable pressure systems, under normal operating conditions, both main & auxiliary
pumps remain connected to a system regardless of which pump is being powered and hence it is
important that that stanbye pump doesn’t become motored. There is two different methods.
Can have a ratchet locking mechanism which prevents counter rotation and when the pump is
running the pawls will be flung to the outside due to centrifugal forces.
Alternatively can use a pair of solenoid isolation valves.
