TM 5-3805-280-24-2
Fuel System Operation and Tests
115
retainer into a circular groove on the rotor. It then flows
The supply pump at rear of rotor is a positive
61
through a connecting passage in the head to the
displacement vane-type pump enclosed in the end
automatic advance and up through a radial passage
cap. The end cap also houses supply pump inlet (17),
and then through a connecting passage to the
fuel strainer and pressure regulator (6). Supply pump
metering valve. The radial position of the metering
pressure is automatically compensated for viscosity
valve, controlled by the governor, regulates flow of the
effects due to temperature changes and fuel grade
fuel into the radial charging passages which
variations.
incorporates the head charging ports.
The distributor rotor incorporates two charging ports
As the rotor revolves, the two rotor inlet passages
(18) and a single axial bore (passage) with one
register with the charging ports in the hydraulic head,
discharge port to serve all head outlets (7) to the
allowing fuel to flow into the pumping chamber. With
injection lines. The rotor rotates in bore of hydraulic
further rotation, the inlet passages move out of registry
head. Metering valve (8) bore, charging ports and
and the discharge port of the rotor registers with one
discharge fittings are located in the head.
of the head outlets. While the discharge port is
opened, the rollers contact the cam lobes forcing the
This pump contains its own mechanical governor. The
plungers together. Fuel trapped between the plungers
centrifugal force of the weights (12) in their retainer is
is then pressurized and delivered by the nozzle to the
transmitted through a sleeve to a governor arm and
through a positive linkage to the metering valve. The
metering valve can be closed to shut off fuel through a
Self-lubrication is an inherent feature of the pump's
solid linkage by an independently operated shut-off
design. As fuel at transfer pump pressure reaches the
lever.
charging ports, slots on the rotor shank allow fuel and
any entrapped air to flow into the pump housing cavity.
The automatic speed advance (13), advances or
retards (hydraulically) the beginning of fuel delivery
Additionally, an air vent passage in the hydraulic head
from the pump. The advance responds to changes in
connects the outlet side of the transfer pump with the
speed only, or to a combination of speed and load
pump housing. This allows air and some fuel to be
changes.
bled back to the fuel tank via the return line. The fuel
thus bypassed fills the housing, lubricates the internal
Fuel is drawn from the supply tank through filters into
components, cools and carries off any small air
the pump inlet through the inlet filter screen by the
bubbles. The pump operates with the housing
vane type fuel transfer pump. Some fuel is bypassed
completely full of fuel; there are no dead air spaces
through the pressure regulator assembly to the suction
anywhere within the pump.
side.
A cold start switch is optional and aids in cold start-up
Fuel under transfer pump pressure flows through the
operation.
center of the transfer pump rotor, past the rotor
RG,115,JW7694 1924NOV972/2
13-588