PBS Distributor Injection System.

second drilling in the head is aligned with the upper injector radial groove

to drain away excess fuel. A fuel drain at the flywheel end of the engine

allows return of the unused fuel to the fuel tank. There are four phases of

injection operation:

(a) Metering (figure 54, view A, on the following page). This

phase begins with the plunger just beginning to move downward when the

engine is on the beginning of the compression stroke. The fuel is trapped

in the cup, the check ball stops the fuel from flowing backwards, and the

fuel begins to be pressurized. The excess fuel flows around the lower

annular ring, up the barrel, and is trapped there.

(b) Preinjection (figure 54, view B, on the following page). The

plunger is almost all the way down, the engine is almost at the end of the

compression stroke, and the fuel is being pressurized by the plunger.

(c) Injection (figure 54, view C, on the following page). The

plunger is almost all the way down, the fuel is injected out the eight

orifices, and the engine is on the very end of the compression stroke.

(d) Purging (figure 54, view D, on the following page). The

plunger is all the way down, injection is finished, and the fuel is flowing

into the injector, around the lower annular groove, up a drilled passageway

in the barrel, around the upper annular groove, and out through the fuel

drain. The cylinder is on the power stroke. During the exhaust stroke, the

plunger moves up and waits to begin the cycle all over again.

g. PBS Distributor Injection System.

(1) Overall System Operation (figure 55 on page 93). The PSB

distributor system uses a pump that sends measured charges of fuel to each

injector at a properly timed interval. The difference in the PSB system is

that the charges of fuel are sent directly from the pump at the high

pressure that is necessary for injection. This

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