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| Illustration 1 | g00753997 |
(1) Air starter exhaust (2) Starter pinion (3) Air starter (4) Air starter lubricator (5) Air start control valve (6) Barring device (interlock) (7) Solenoid valve with manual bypass (8) Pressure sender (9) Air supply from the ship (10) Air strainer (11) Air regulator (250 psi) (12) Air relief valve (260 - 265 psi) (13) Inlet air valve (14) Line to air shutoff solenoid (15) Main air supply (16) Control circuit | |
An air starting motor can be used in order to turn the engine flywheel with enough rpm in order to start the engine. Operation of the air starting motor is controlled by the Engine Supervisory System. The air starting motor will engage when the requirements for prelube have been met.
The air start solenoid is equipped with a manual bypass valve. The manual bypass valve allows the actuation of the air start solenoid. The use of the manual bypass valve is necessary with the loss of the 24 VDC power supply (black start). System air pressure is taken off upstream of the inlet air valve. This air pressure is used to supply the air shutoff solenoid. If the inlet air valve is shut off, the air pressure to the air shutoff solenoid is still available in order to provide shut off protection.
The air starting motor is mounted on the right side of the engine. Air is contained in a storage tank. The volume of the tank, the air pressure in the tank and the amount of the restriction that is in the system these factors determine the duration of the engine's flywheel rotation.
For starting the engines which do not have heavy loads, the regulator setting is approximately 1034 kPa (150 psi). This setting gives a good relationship between the duration of the air starting motor's rotation and the cranking speeds before the air supply is exhausted.
Note: Minimum recommended cranking speed for start-up is 80 rpm. The fuel system and the ignition system are activated at engine speeds above 50 rpm. The maximum cranking speed of the air starting motor is 150 rpm.
If the engine has a heavy load which cannot be disconnected during starting, the setting of the air pressure regulating valve needs to be higher in order to get high enough speed for easy starting.
The air consumption is directly related to speed. The air pressure is related to the effort that is necessary in order to turn the engine flywheel. The setting of the air pressure regulator can be up to 1723 kPa (250 psi). This will get the correct cranking speed for a heavily loaded engine. With the correct setting, the air starting motor can turn the heavily loaded engine at the same speed and for the same duration as the air starting motor can turn a lightly loaded engine. The maximum pressure for use in the air starting motor is 1723 kPa (250 psi).
For good life of the air starting motor, the air supply should be free of dirt and water. Use a lubricator with "SAE 10W" nondetergent oil for temperature above 0 °C (32 °F). Use air tool oil for temperatures below 0 °C (32 °F).