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| Illustration 1 | g01214486 |
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(1) Air compressor governor
(2) Air compressor (3) Air dryer (4) Pressure relief valve (5) Main air reservoir (6) Relay valve (7) Air starting motor (8) Check valve (9) Drain valve (10) Engine governor control actuator (11) Start control valve (12) Governor control valve (13) Air pressure gauge (14) Air pressure protection valve (15) Check valve (16) Governor air reservoir | |
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| Illustration 2 | g01214506 |
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(1) Air inlet
(2) Vanes (3) Rotor (4) Drive pinion (5) Reduction gears (6) Piston (7) Piston spring | |
The start control valve has a solenoid that is operated electrically from the keyswitch at the operator's panel. When the key is turned to the START position, the start control valve opens in order to allow air from the secondary tank to piston (6) behind the drive shaft. This air pressure compresses spring (7). This allows drive pinion (4) to engage with the flywheel ring gear.
Drive pinion (4) engages the ring gear. A port opens in order to allow air to the relay valve. The relay valve opens the supply line from the air reservoir. This allows a large volume of air to pass through air inlet (1). The air mixes with diesel fuel at the lubricator valve on the way to rotor (3). The air pressure causes vanes (2) to rotate. This air turns the rotor which turns drive pinion (4) and the engine flywheel through a set of reduction gears (5). The air is exhausted at the exhaust outlet of the air motor.
When the engine starts to run, the flywheel will begin to turn faster than drive pinion (4). The drive pinion gear disengages from the flywheel. This prevents damage to the drive pinion or the flywheel gear.
When the keyswitch is released from the START position, the starter control valve closes. The air pressure and flow to piston (6) stops. The piston spring retracts the drive pinion. The movement of piston (6) closes the air passage that activates the relay valve. The relay valve closes in order to stop the flow of air to the starting motor rotor.