SHUTOFF AND ALARM SYSTEMS
SYSTEMS OPERATION
This system gives high water temperature, low oil
pressure and overspeed protection to the engine.
Rack solenoid (6) is connected to the fuel rack by
linkage. When it is activated it will move to stop the flow
of fuel to the engine. The rack solenoid can be activated
by oil pressure switch (1), water temperature contactor
(3) or the overspeed switch that is part of dual speed
switch (4).
If the oil pressure is too low or the coolant
temperature is too high, oil pressure switch (I ) or water
temperature contactor (3) will close to complete the
circuit and activate rack solenoid (6).
NOTICE
To help prevent damage to the engine, find and
correct the problem that caused the engine to
shutdown before the engine is started again.
The engine speed is felt by magnetic pickup (5). As
the teeth of the flywheel go through the magnetic lines of
force around the pickup, an AC voltage is made. Dual
speed switch (4) measures engine speed from the
frequency of this AC voltage.
If the engine speed increases above the overspeed
setting (I 18% of rated speed) of the dual speed switch,
the overspeed switch [which is part of dual speed switch
(4)] will close across terminals DSS-7 and DSS-8. This
completes the circuit to rack solenoid (6) through
pressure switch (2) and water temperature contactor (3)
to activate the solenoid and shutdown the engine.
NOTICE
To help prevent damage to the engine find and
correct the problem that caused the engine to
overspeed, before the engine is started again.
After an overspeed shutdown, a button on the dual
speed switch must be pushed to open the overspeed
switch before the engine will run.
Diode assembly (7) is used to stop arcing, for
protection of the system.
An oil pressure (time delay) or fuel pressure switch
(2) is used to prevent discharge of battery (9) through the
solenoid when the engine is stopped. The dual speed
switch can be connected to the battery constantly
because it uses less than 20 MA of current when the
engine is stopped.
NOTE: On systems that use an earlier type oil pressure
switch, it will be necessary to push the manual override
button before the engine can be started. Oil pressure will
return the manual override button to the run position.
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