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.