In air motor starting system, the
engine is started by a starting air motor which is operated by compressed air.
Figure below shows the compressed air system for starting, stopping and
fuel limiting for auxiliary engines on ships.
Refer to the figure above.
Compressed air reaches the auxiliary engine at 30 bar pressure. The air
pressure is reduced to 6 bar with a reduction valve. A safety valve is also
fitted in the line after reducing valve to protect the air starting system
components. Air then enters air starting valve (5) and wait there.
When ‘START’ button on the control panel is activated, starting solenoid
valve (5) is opened to supply compressed air into the starting air motor
(1). Then, the pinion of the air starting motor is engaged with the
gear rim of the engine flywheel. As the pinion moves, relay valve (2) is
supplied with air and it allows air to the starting air motor turbine wheel.
Now air motor turns crankshaft of the engine. When the engine rotating
speed reaches predetermined speed, fuel oil is injected into
the combustion chamber. Then, starting is completed and the pinion of
the air starting motor is disengaged from the gear rim at predetermined
speed.
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