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| Illustration 1 | g00334020 |
Typical example of an air starting system (1) Lubricator. (2) Relay valve. (3) Line. (4) Tee. (5) Starter control valve. (6) Hose. (7) Starting motor. (8) Deflector. (9) Line. (10) Drive housing. (11) Line. | |
The air starting motor can be mounted on either side of the engine. Air is normally contained in a storage tank. The volume of the tank and the air pressure in the storage tank will determine the operating time of the air starting motor.
For starting the engines which do not have heavy loads, the regulator setting is approximately 690 kPa (100 psi). This setting gives a good relationship between the cranking speeds that are fast enough for easy starting and the operating time of the air starting motor. The operating time of the air starting motor depends on the air supply to the air starting motor.
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 crank the engine. The setting of the air pressure regulator can be up to 1030 kPa (150 psi). A high setting will give the correct cranking speed for a heavily loaded engine.
Any air supply can be used if the air supply has the correct pressure and the correct volume. For good life of the air starting motor, the air supply should be free of dirt and water. Use a lubricator with "SAE 10" nondetergent oil for temperature above 0°C (32°F). Use air tool oil for temperatures below 0°C (32°F). The maximum pressure for use in the air starting motor is 1030 kPa (150 psi). Higher pressures can cause problems.
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| Illustration 2 | g00334021 |
6N-4147 Air Starting Motor (12) Vanes. (13) Rotor. (14) Pinion. (15) Gears. (16) Piston. (17) Spring. | |
An air compressor supplies the air that is used by the starting motor. The air is sent through a pressure regulator. From the pressure regulator, the air goes through hose (6) to tee (4). The flow of air is then stopped by relay valve (2) until the starter control valve (5) is activated. The starter control valve (5) is connected to the air supply line before relay valve (2) by line (3). When the starter control valve (5) is activated, the air is sent from the starter control valve through line (11) to the drive housing (10). The air flows to piston (16) for pinion (14). The air pressure on piston (16) compresses spring (17). The compression of spring (17) allows pinion (14) to engage the flywheel gear. When the pinion is in engagement, the air flows from the drive housing (10) through line (9) to relay valve (2). This air activates relay valve (2). This allows the main air supply from tee (4) to go through lubricator (1) and into starting motor (7) .
The air that contains lubrication oil goes to the air motor. The air pressure pushes the vanes (12) in the rotor (13). This turns the rotor which is connected by gears (15) to the starter pinion (14). The starter pinion (14) turns the engine flywheel. The air flows out of the starting motor through the deflector (8) or an air silencer.
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| Illustration 3 | g00334027 |
Typical example of the air flow through the air starting motor | |
Once the engine starts running, the flywheel will start to turn faster than the starter pinion (14). The pinion (14) retracts under this condition. this prevents damage to the motor, the pinion (14) or the flywheel gear.
When the starter control valve (5) is released, the air pressure and the flow to the piston (16) behind starter pinion (14) is stopped. The piston spring (17) retracts the pinion (14). The relay valve (2) stops the flow of air to the air starting motor.