TM 9-6115-668-13
1.14 FUNCTIONAL DESCRIPTION.
1.14.1 Engine Preheating Assembly Operation.
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Circuit breakers F1 to F11 and F101 to F103 in control cabinet assembly are closed (figure FO-1).
1.14.1.1 Start- up, Time t = 0.
On control cabinet assembly, MASTER SWITCH (S1) to ON:
+24V is applied to the control cabinet 24-V circuits through F1 to F9.
BATTERY CHARGING CONTROL indicator lamp (H2) and OIL PRESSURE indicator lamp (H3) light up
(+Vreg from N5).
+24 V is present at terminal X101, connector 1 of the engine preheating assembly.
On control cabinet, press HEATING ON illuminated pushbutton switch (S102):
+24 V is applied, through S102, to the coils of K111, K107, K110, K101 and K106.
Auxiliary contactor K111 energizes and switches +24 V, through N-O contact 30-87, to N-O contacts
30-87 of K103 and K104 (input voltage to heating control system).
Auxiliary contact K101 energizes and switches +24 V:
through N-O contact 30-87 and R100 to R102 to glowplug R108, which preheats the combustion
chamber. R100 to R102 heat speed governor assembly N1 in the control cabinet through N-O
contact 30-87 and V106 to the coil of K109. Auxiliary contactor K109 energizes:
+Vreg
is applied through N-O contact 13-14 to the HEATING ON indicator lamp (H101), which
lights up; S102 is bridged through N-O contact 23-24 and S103/S104 (latch);
+24 V is applied through N-O contact 33-34 to the puller magnet of the air flap, which opens;
N-C contact 71-72 disconnects the coil of K10 (oil pressure) from +24 V (shutoff delay due to
insufficient oil pressure).
Time relay K106 energizes and blocks excitation of K103. K103 prevents the excitation of K105, i.e.
the solenoid valve in the intake manifold is not connected to +24 V through N-O contact 30-87 of
K105.
1.14.1.2 Time t approximately 1 minute.
K106 deenergizes. +24V is applied through N-C contact 15-16 to the coil of K103.
Auxiliary contactor K103 energizes and switches +24 V, through N-O contact 30-87:
and V105 to the coil of K109;
and V102 to the fan motor of the heating system;
to the coils of K104, K105, and K108.
Auxiliary contactor K105 energizes and switches +24 V, through N-O contact 30-87, to the solenoid
valve in the intake manifold (diesel fuel can be drawn into the heating system).
If burner monitor temperature switch S109 is closed (burner ignited), auxiliary contactor K104 energizes
and latches itself through N-O contact 30-87. The fuel-air mixture is ignited and heats the air-oil-heat
exchanger.
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