injection nozzles. As the fuel is pumped into
the fuel service tanks, it is purified. From
the service tank the fuel is filtered before
reaching the injection system, where the larger
particles of the solids suspended in the fuel
are trapped in the strainer. The filter separates
the fine particles of foreign matter that pass
through the strainer. Most strainers have a
drain plug for removing the water, sludge, and
other foreign matter. The strainers should be
There are many methods of fuel injection
and just as many types of injection pumps
and nozzles. The unit injector, shown in
figure 7-9, consists basically of a small cylinder
and a plunger and extends through the cylinder
head to the combustion chamber. A cam,
located on the camshaft adjacent to the
cam that operates the exhaust valves, acts
through a rocker arm and depresses the
plunger at the correct instant in the operating
drained once each day.
cycle.
Figure 7-10.—Typical lubication system.
7-10
