Page 31 - Webster Service Manual

One Pipe System
Fuel enters the fuel unit
through the inlet port and is
drawn into the front cover
chamber. A vacuum, creat-
ed by an inner and outer
rotating gear set, pulls oil
through the rotary filter and
into the gears. As oil
moves around the gears, it
is compressed, creating a
higher pressure. Oil leav-
ing the gear set branches
into two paths. One path leads to the pressure regulat-
ing chamber. A second path directs oil to the bleed
valve. Oil flowing into the pressure regulating chamber
branches into two paths. Up to three gallons per hour
can flow out the nozzle port, and the remaining oil by-
passes the pressure regulator , returning to the front
cover chamber.
Fuel subject to vacuum
Fuel at atomization pressure
Fuel at return pressure
Two Pipe System
The by-pass plug, inserted through the bleed valve port,
blocks the surplus oil return to the front chamber . This
oil is directed to the return port and back to the storage