sweeps up through the engine to draw off vapors through the breather
tube and collector.
of an air cleaner, blower, cylinder block air box, cylinder liner
intake ports, exhaust valves, and a turbocharger. In the scavenging
process, the blower forces a charge of air into the cylinders and
forces exhaust gases out through the open exhaust valves.
also helps cool the internal parts of the engine, especially the
exhaust valves. The turbocharger increases the velocity and pressure
of the intake air, and forces a greater volume of air into the
This higher volume of air produces a more constant air
supply to the blower and increases the engine power.
h. The Electrical System.
The electrical system consists of a
starter motor, engine preheater, and associated wiring. The starter
motor has a shift lever and solenoid plunger (totally enclosed to
protect against dirt penetration), and a sprag overrunning clutch.
Pressing the starter switch energizes the starter motor solenoid,
which engages the starter motor pinion teeth with the teeth of the
flywheel ring gear.
Closing the contacts in the starter motor
solenoid energizes the starter motor, and the starter motor solenoid
drives the pinion and rotates the engine.
When the engine starts,
the sprag clutch permits the pinion to overrun on its shaft.
clutch prevents the starter motor from overspeeding while engaging
the starter switch and the engine is running.
The purpose of the preheater is to heat the air entering the
This assists in igniting the fuel at low ambient
To heat the air, a spark plug ignites fuel sprayed
into the cylinder block air box.
The air entering the engine must
pass through the air box; as it does, it absorbs the heat created by
the flame and goes directly into the cylinders.
i. The Gear Train. Enclosed at the rear of the engine, between
the engine end plate and the flywheel housing, is a helical gear
train (Fig. 4). The gear train consists of a crankshaft, idler, fuel
pump drive, and two camshaft gears.
The idler gear rotates on a
The crankshaft gear requires a pressed fit on the
keyed crankshaft, and the camshaft gears require a pressed fit on the
Once pressed in place, the camshaft gears use a
retaining nut; a lock plate secures them in place.
gears mesh with each other and run at the same speed as the
The gears have timing marks stamped on their face
to ensure correct gear train timing. Overflow oil from the camshaft
pockets, camshaft end bearings, and idler gear bearing lubricates the
gear train. Oil from the main cylinder block oil gallery lubricates
the fuel pump drive gear and idler gear bearing.