The main rotating components (Figure 4-32) are the drive shaft, the distributor rotor, the transfer pump blades and the governor.
The drive shaft engages the distributor rotor in the hydraulic head. The drive end of the rotor incorporates two pumping plungers.
The plungers are actuated toward each other simultaneously by an internal cam ring through rollers and shoes which are carried in slots at the drive end of the rotor. The number of cam lobes equals the number of engine cylinders.
The hydraulic head contains the bore in which the rotor revolves, the metering valve bore, the charging ports and the head discharge fittings. The high pressure injection lines to the nozzles are fastened to these discharge fittings.
The DB2 Pump is an inlet metering pump. That is, it has a pumping period with a variable beginning, and a constant ending.