Supply Pump

Fig. 3 Supply Pump:

The supply pump, Fig. 3, surrounds the input shaft, its impeller concentric with the shaft and driven by a Woodruff key. In turn, the impeller runs inside an eccentric ring fixed to the housing.

Fig. 14 Vane type fuel supply pump:

The impeller's four vanes, Fig. 14, are forced outward by centrifugal action against the eccentric ring; this motion is reinforced by the fuel between the vanes' undersides and the impeller. Fuel moves through the inlet port in the injection pump's cavity and a kidney shaped recess in the space formed by the impeller, vane and eccentric ring. The rotary motion causes the fuel between adjacent vanes to be forced into the upper kidney-shaped recess and through a bore into the pump cavity. Simultaneously, a portion of the fuel flows through a second bore to the pressure-control valve.