While the discharge port is open, the movement of the rotor causes the rollers to contact the cam lobes, forcing the plungers together. The fuel is thus pressurized until the rollers pass over the top of the injection cam, when the pressure starts to drop. (Figure 4-43).
The fuel then flows through the discharge outlet and discharge port to the injection nozzle. (Figure 444).
The magnitude of this pressure drop is controlled by the delivery valve which retains a definite residual pressure in the discharge circuit. This pressure is low enough to assure prompt nozzle closing yet high enough to prevent cavitation of the fuel between injections. (Figure 4-45).
