Showing posts with label STEERING GEAR. Show all posts
SHIP STEERING CONTROL AND CONTROL SYSTEMS
ELECTRO HYDRAULIC STEERING GEAR
CONTROL SYSTEMS
(I) NON FOLLOW UP SYSTEMS
(II) FOLLOW UP SYSTEMS
With these systems the motor
runs continuously. Duplicate motors and duplicate feeders are normally provided
and in certain installations a change-over switch is provided so that each
motor may be supplied by either feeder.
Short circuit protection only
is provided in these feeder circuits, the normal overload protection being
replaced by an overload alarm.
CONTROL SYSTEMS
These are of three basic
types:-
(I) NON FOLLOW UP SYSTEMS
With these systems the gear
will run and the rudder will continue to turn while the steering wheel or other
controller is moved from its central position. Rudder movement is stopped only
when the steering control is centred once again (or when the rudder is brought
up against the stops).
It will be obvious that placing the filler amidships merely stops application of helm and does not remove it. Removal of helm must be effected by moving the tiller to the opposite side. Controllers with non follow up systems take the form of a wheel or a tiller lever or push buttons. A rudder indicator is fitted to indicate rudder movement.
It will be obvious that placing the filler amidships merely stops application of helm and does not remove it. Removal of helm must be effected by moving the tiller to the opposite side. Controllers with non follow up systems take the form of a wheel or a tiller lever or push buttons. A rudder indicator is fitted to indicate rudder movement.
(II) FOLLOW UP SYSTEMS
With these systems movement of
the rudder follows the movement of the steering controller e.g. if the
controller is moved to indicate a desired rudder position the rudder will turn
until the actual rudder angle is the same as the desired rudder angle shown on
the steering pedestal after which rudder movement will cease, the controller
remaining offset from its central position.
(III) AUTOMATIC SYSTEMS
With these systems the
steering control circuits are controlled by signals received from the master
compass, so that the ship is automatically held on to a selected course.
Primarily the system is so arranged that when the vessel is on course the rudder is amidships but as soon as the compass indicates an error the auto pilot applies an amount of rudder sufficient to bring the vessel back on course. By the time the vessel is on course again the applied correcting rudder has been removed.
With some systems, should it be required to alter the course being steered by the auto pilot by a few degree, this can be done by a Trim Switch and without necessarily reverting to hand steering.
Primarily the system is so arranged that when the vessel is on course the rudder is amidships but as soon as the compass indicates an error the auto pilot applies an amount of rudder sufficient to bring the vessel back on course. By the time the vessel is on course again the applied correcting rudder has been removed.
With some systems, should it be required to alter the course being steered by the auto pilot by a few degree, this can be done by a Trim Switch and without necessarily reverting to hand steering.
Any and all of the above
systems can be applied to both all electric or electro hydraulic steering
systems so that the following may be fitted:-
(i) Hand Electric (Follow Up)
(ii) Hand Electric (Non Follow Up)
(iii) Hand Hydraulic (“Telemotor Control”)
(iv) Automatic
(ii) Hand Electric (Non Follow Up)
(iii) Hand Hydraulic (“Telemotor Control”)
(iv) Automatic
and its normal practice to
fit at least two of the systems (i), (ii) and (iii).
Fig indicates Follow Up,
Non Follow Up and Auto Systems fitted to electro hydraulic power systems.
Thus it will be obvious that
an electric system of steering control consists essentially of:-
i)Steering pedestal or bridge unit. This produces electrical
impulses by operation of the steering control.
ii)Amplifier or control unit to transmit these impulses to the steering flat.
iii)After power unit to translate these impulses into mechanical movement of the power steering system.
ii)Amplifier or control unit to transmit these impulses to the steering flat.
iii)After power unit to translate these impulses into mechanical movement of the power steering system.
Tag :
STEERING GEAR
STEERING GEAR TESTING
PRIOR DEPARTURE
- STEERING GEAR SHOULD BE CHECKED AT LEAST ONE HOUR PRIOR DEPARTURE FROM PORT.
- THE DUTY OFFICER AND THE SENIOR DUTY ENGINEER SHOULD CARRY OUT THE TESTS TOGETHER.
- TELEMOTOR TRANSMITTER OIL LEVEL TO BE CHECKED.
- OIL LEVEL OF ACTUATING SYSTEM TANK SHOULD BE CHECKED AND REPLENISHED IF NECESSARY.
- PALLESTER BEARING AND BOTTOM SEA GLAND CHECKED AND GREASED.
- ALL LINKS ON STEERING GEAR CHECKED TO BE IN ORDER.
- FIRST ONE PUMP IS STARTED FROM THE BRIDGE AND THE WHEEL TURNED FROM PORT TO STARBOARD TO CHECK THE TELEMOTOR RESPONSE.
- NEXT WITH BOTH THE OFFICERS IN THE STEERING FLAT THE WHEEL IS TURNED FROM HARD-A-PORT TO HARD-A-STARBOARD AND THE RUNNING CHECKED.
- CHECK MADE TO SEE IF THE HELM ANGLE INDICATOR ON THE BRIDGE AND THE LOCAL MECHANICAL ONE CORRESPOND TO EACH OTHER FOR ALL POSITIONS.
- THE FIRST PUMP IS SHUT OFF AND SECOND ONE IS STARTED AND CHECKS 8 AND 9 REPEATED.
- THEN BOTH THE PUMPS ARE PUT IN PARALLEL OPERATION AND CHECKS 8 AND 9 REPEATED.
- AFTER TEST IS SATISFACTORY ONE PUMP IS SHUT OFF. WITH ONE PUMP RUNNING AND IF IT’S OF HELESHAW TYPE, IT SHOULD BE ENSURED THAT THE WHEEL IS ACTUATED EVERY 15 MINUTES, SO THAT THE PUMPS PARTS GET PROPERLY LUBRICATED.
- OPERATION OF AUXILIARY STEERING GEAR AND USE OF THE SECOND PUMP, WHICH ACT AS AN AUXILIARY.
- OPERATION OF REMOTE CONTROL (TELEMOTOR) SYSTEM OR SYSTEMS FROM MAIN BRIDGE STEERING POSITIONS.
- OPERATION OF STEERING REAR USING THE EMERGENCY POWER SUPPLY.
- THE ALARMS FITTED TO THE REMOTE CONTROL SYSTEM AND THE STEERING GEAR POWER UNITS SHOULD BE CHECKED FOR CORRECT OPERATION.
- DURING THESE TESTS RUDDER SHOULD BE MOVED THROUGH ITS FULL TRAVEL IN BOTH DIRECTIONS AND THE VARIOUS EQUIPMENTS ITEMS, LINKAGES, ETC., VISUALLY INSPECTED FOR DAMAGE OR WEAR.
- THE COMMUNICATION SYSTEM
BETWEEN THE BRIDGE AND THE STEERING GEAR COMPARTMENT SHOULD ALSO BE
OPERATED.
BEFORE
ARRIVING PORT
- ONE HOUR BEFORE PICKING UP THE PILOT, THE SPEED SHOULD BE REDUCED AND ENGINE MANEUVERS AND ASTERN RUNNING CHECKED. ALSO STEERING GEAR ACTUATION CHECKED.
- BOTH PUMPS ARE PUT ON AND MOVEMENT ON EITHER SIDE CHECKED.
- HELM ANGLE INDICATOR AND THE
LOCAL INDICATOR IN STEERING GEAR COMPARTMENT CHECKED FOR CORRECT AND
MATCHING RESPONSE ON EITHER SIDE.
Tag :
STEERING GEAR