Figure 5-33.Fuel intake flow diagram.
Figure 5-33 shows fuel intake at the hydraulic head.
Injection (fig. 5-34) begins when fuel flows around the
fuel plunger annulus (fig. 5-35) through the open
distributing slot to the injection nozzle. A continued
upward movement of the fuel plunger causes the spill
passage to pass through the plunger sleeve (fig. 5-36).
This reduces pressure, allowing the fuel delivery valve
to close, ending injection. This is accomplished
through a single plunger, multi-outlet hydraulic head
assembly (fig. 5-31).
The plunger is designed to operate at crankshaft
speed on four-cycle engines. It is actuated by a
camshaft and tappet arrangement. The pump camshaft,
Figure 5-35.Fuel delivery flow diagram.
which also includes the gearing for fuel distribution, is
supported on the governor end by a bushing-type
bearing and by a ball roller bearing on the driven end.
An integral mechanical centrifugal governor (fig. 5-37),
that is driven directly from the pump camshaft without
gearing, controls fuel delivery in relation to engine
speed. This pump has a smoke limit cam within the
governor housing to assist in controlling exhaust smoke
of various fuels. The mechanical centrifugal advance
unit of this pump provides up to g-degrees advance
timing and is driven clockwise at crankshaft speed.
Figure 5-34.Beginning of fuel delivery flow diagram.
Figure 5-36.End of fuel delivery flow diagram.