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Bridge control of a large slow speed propulsion enigne how starting and reversal is achieved

Forr large propulsion engines the Bridge Control is achieved by using the telegraph to 
select the desired speed and direction. 
When the bridge telegraph is placed in Stop, the fuel is prevented from injecting as 
the fuel pump puncture valves are energised. 
When the bridge telegraph is moved to an ahead command, the air start and fuel cams 
are placed in the required direction, and the start command is given. This will admit 
starting air to the engine. Once the engine is turning above the starting speed, the air is 
closed and fuel is admitted. The quantity of fuel admitted will depend on the position 
of the telegraph handle, i.e. slow ahead, full ahead, etc. 
When the bridge telegraph is moved to an astern direction, the air start and fuel cams 
are reversed. Once the air start is reversed, the engine will start as detailed for the 
ahead start

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