Abstract: A fuel injection system (18) is calibrated as an assembled system. The fuel injection system (18) includes a unit pump (10) a cam follower (24), a joined fuel injection line (14) and injection nozzle (16). The fuel injection system (18) is mounted to a test stand an is subsequently calibrated to a specified fuel delivery and timing. The relative positions of the unit pump (10) and fuel injection nozzle (16) are fixed during calibration. The assembled fuel injection system is packaged and delivered so that the calibrated system can be installed in the relative positions fixed during calibration.

Abstract: A hydraulically actuated servo piston and hydraulic advance piston are integrated into the cam follower of a unit pump or injector to provide variable advance for an injection event produced by the pump or injector. The servo piston is nested in the advance piston with fluid passageways in the advance piston selectively opened or closed by movement of the servo piston. The full pressure of a hydraulic pump is available to the advance piston for powering the advance function, while stepwise reduced levels of hydraulic pressure from the same hydraulic pump are applied to control movement of the servo piston. A damping orifice restricts flow of hydraulic fluid to and from the servo piston.

Abstract: A hydraulically actuated servo piston and hydraulic advance piston are integrated into the cam follower of a unit pump or injector to provide variable advance for an injection event produced by the pump or injector. The servo piston is nested in the advance piston with fluid passageways in the advance piston selectively opened or closed by movement of the servo piston. The full pressure of a hydraulic pump is available to the advance piston for powering the advance function, while stepwise reduced levels of hydraulic pressure from the same hydraulic pump are applied to control movement of the servo piston. A damping orifice restricts flow of hydraulic fluid to and from the servo piston.