Figure 4-42.--Rotor in discharge position (DC pump).
Figure 4-44.--Regulating piston during hand priming.
head, at which time the rollers simultaneously contact
the opposing cam lobes. The cam lobes force the
are located on either side of the charging port of the
rotor near its flange end. These grooves carry off fuel
the cylinder through the outlet port into the outlet
from the hydraulic head charging ports to the housing.
passage in the hydraulic head and the fuel injection line
This flow of fuel lubricates the cam, rollers, governor
connected to this passage (fig. 4-42). The cam is
parts, etc. The fuel flows through the entire pump
relieved to allow a slight outward movement of the
housing, absorbs heat, and is allowed to return to the
roller before the discharge port is closed off. This action
supply tank through a fuel return line connected to the
drops the pressure in the injection line enough to give
pump housing cover, thus providing for pump cooling.
sharp cutoff injection and prevent nozzle dribbling.
The end plate functions to provide passages for fuel
A displacement type delivery valve (fig. 4-42) is
and to cover and absorb end thrust of the transfer pump,
located in the drive passage of the rotor between the
to house the pressure regulator valve, and to house the
charging port and the discharge port of the rotor. It
priming bypass spring, which permits fuel to bypass the
remains closed during charging and opens under high
transfer pump during hand priming.
pressure as the plungers are forced together. Its purpose
is to aid, by injection line pressure relief, the cam
Figures 4-43, 4-44, and 4-45 show the regulating
"retraction" previously described. Two small grooves
piston in three positions: at rest, during hand priming,
and in operation. Figure 4-43 shows the piston covering
R E G U L AT I N G
Figure 4-45.--Regulating piston in pressure regulating
Figure 4-43.--Regulating piston at rest.