Main engine maneuvering system

The starting handle controls three micro switches that convey the following signals

1. Stop signal – Instantaneous
2. Start Signal – Instantaneous
3. Run signal – Varying signal

STOP Signal: As long as the stop signal has been pressed, it shall keep the control air at 7 bar to pass through and keep the picture valve pressed there by not to allow the fuel to be admitted to the fuel pump.

START signal: As soon as the starting handle is moved the start micro switch shall be pressed and shall allow the passage of 7B control hit through it, if no interlock had been activated then it shall allow further passage of the air. Now if the reversing has completed then it shall allow the air to pass through the air cylinder which shall operate and open the auto start valve on the main air manifold.

Now the starting air@ 30Bar shall be supplied to the distributor and pass to the starting air valve (Pilot air) of a particular unit that is in starting position to start the engine.

RUN signal: Once the engine has started we shall further press the starting handle to the run position, where the start signal ends. The run micro switch being the varying type, more the handle is moved, more the switch would be compresses and the output of the same shall vary accordingly. The varying signal control the 7B control air output that is fed to the governor to increase the fuel proportionately. Main engine manoeuvring system

REVERSING: The engine has stopped in the astern position and it is desired to start the engine in Ahead direction hence the AHD/AST lever to the ahead position, allowing the 7B control air to pass through the pressed AHD micro switch and passes to 1. The fuel pump to reverse the cam position via the reversing cylinder 2. To the starting air distributor reversing cylinder to reverse the distributor. Main engine manoeuvring system

REVERSING COMPLETED INTERLOCK: As reversing has completed, the shaft of the starting air distributor reversing cylinder shall move outwards to press the AHD micro switch, allowing a part of control air to pass through the IL and a block valve to release and fulfil the reversing completed interlock. This is provided so that in the event of the reversing cylinder being stuck between AHD/AST micro switch, in that condition, the interlock shall not allow the AUTO START v/v to open.

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Watch HIMT video on reversing marine engines https://www.youtube.com/watch?v=02dNCD-aD9Y