10.13.
Distributor-type Injection Pump
In distributor-type fuel-injection pumps system (Fig. 10.25) two or more plungers serve all the cylinders of the engine, and the fuel is injected to each cylinder in turn by a distributor. Two main types of pump in use are the rotary and axial plunger distributor pumps. Rotary types distributor pump are those in which the plungers reciprocate in the head of the distributor rotor while revolving around its axis, similar to the Lucas and Standyne units. Whereas in the axial plunger type distributor pump, the pumping plunger is coaxial with the drive shaft and, rotating with it, serves also as the distributor, similar to the Bosch VE series.
Fig. 10.25. Distributor-type fuel-injection-pump system.
Distributor pumps are generally lighter and more compact, are less costly, than their in-line counter parts. Also, their governors and injection advance devices are simpler and smaller. This type of pump usually incorporates a transfer pump used for keeping it full of fuel and also for powering many of the control systems. Consequently, transfer pump delivery pressures of up to 785 kPa and above are necessary. For achieving this pressure, vane type pumps are generally used.
