Lesson 1/learning Event 1
- The contact points close as the bellows fully contract. This causes the electromagnet to pull the
armature down and repeat the pumping process.
- The pump will stop when the fuel pressure is high enough to hold the bellows expanded against the
return spring. The operating pressure of the pump is determined by the return spring pressure.
FIGURE 4. VANE-TYPE ELECTRIC PUMP.
Vane Type. An integral steel rotor and shaft, one end supported in the pump flange and the other end in
the cover, revolves in the body. The bore of the body is eccentric to the rotor. Two sliding vanes, 180
apart in slots in the rotor, are pressed against the body bore by springs in the slots. When the shaft is
rotated, the vanes pick up fuel at the inlet port and carry it around the body to the outlet side, where the fuel
is discharged. Pressure is produced by the wedging action of the fuel as it is forced toward the outlet port by
the vane.
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