Question - With Reference To Bridge Control Of A Large Man B&w Slow Speed Propulsion Engine Explain How Starting And Reversal Are Achieved ?
Answer -
For 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.