TM 5-3895-383-24
Fuel Ratio Control
The turbocharged engine uses a fuel ratio control (FRC) to
control smoke during acceleration at low boost levels. The
FRC restricts the amount of fuel to the combustion chambers
until sufficient boost has been achieved.
Governor Linkage And Fuel Ratio Control Schematic
(1) Governor output shaft. (2) Inlet port. (3) Fuel ratio control.
(4) Retainer shaft. (5) FRC leer. (6) Limit lever setscrew. (7)
FRC lever setscrew. (8) Limit leer.
Fuel ratio control (3) operates on boost air pressure delivered
by a tube between inlet port (2) and the engine's inlet manifold.
At low boost, retainer shaft (4) is held stationary by springs
inside the FRC. When the operator demands more fuel,
governor output shaft (1) moves in the FUEL ON direction until
limit lever (8) contacts setscrew (7) of FRC lever (5). With
FRC lever (5) restrained from FUEL ON (CW) movement by
the FRC, further FUEL ON movement of governor output shaft
(1) is stopped. Thus, overfueling is prevented.
As engine power increases, boost pressure also increases.
This pressure acts against a diaphragm inside the FRC. When
boost is sufficient, spring force inside the FRC is overcome and
retainer shaft (4) moves to the right. Now FRC lever (5) and
limit lever (8) can rotate CW, allowing governor output shaft (1)
to move in the FUEL ON direction until limit lever (8) contacts
limit lever setscrew (6).
When boost pressure decreases, springs inside fuel ratio
control (3) return retainer shaft (4) to normal position. FUEL
ON movement of governor output shaft (1) is again restricted.
Fuel Shutoff Solenoid
Fuel Shutoff Solenoid (Latching Type)
(1) Solenoid. (2) Button
The fuel shutoff mechanism is activated by an energized to run
(ETS) latching type solenoid. A spring loaded plunger inside
the solenoid acts on a lever assembly within the front housing
of the governor. This lever assembly pushes the governor
output shaft to FUEL OFF position when the plunger of the
solenoid is released electrically or manually at engine
shutdown. At startup, the solenoid is energized to latch in the
run position. The governor output shaft is then free to move to
the FUEL ON position.
Engines with latching type solenoids can be manually shut off
by pushing in on button (2). The solenoid CANNOT be
manually latched in the run position for starting.
NOTE:
Engines for some applications will have a
conventional
"energize-to-run"
(ETS)
shutoff
solenoid (no manual latching action is provided).
NOTE:
Both types of solenoids are available in either 12V
or 24V depending on the application and electrical
system that is provided.
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