SHUTOFF AND ALARM SYSTEMSCOMPONENTS
SYSTEMS OPERATION
SHUTOFF AND ALARM SYSTEM COMPONENTS
OIL PRESSURE SWITCH
Micro Switch Type
The oil pressure switch is used
to give protection to the engine from damage because of
low oil pressure. When oil pressure lowers to the
pressure specifications of the switch, the switch closes
and activates the rack shutoff solenoid.
On automatic start/stop installations, this switch
closes to remove the starting system from the circuit
when the engine is running with normal oil pressure.
This switch for oil pressure can be connected in a
warning system for indication of low oil pressure with a
light or horn.
As pressure of the oil in bellows (6) becomes higher,
arm (4) is moved against the force of spring (3). When
projection (10) of arm (4) makes contact with arm (9),
pressure in the bellows moves both arms. This also
moves button (8) of the micro switch to activate the
micro switch.
OIL PRESSURE SWITCH (Micro Switch Type) 1.
LocknuL 2. Adjustment screw. 3. Spring. 4 Arm.
. Spring. Bellows 7. Latch plate. L Button for micro
switch. 9. Arm. 10. Projection of arm.
Some of these switches have a "Set For Start"
button.
When the button is pushed in, the micro switch is in the
START position. This is done because latch plate (7)
holds arm (9) against button (8) of the micro switch and
the switch operates as if the oil pressure was normal.
When the engine is started, pressure oil flows into
bellows (6). The bellows move arm (4) into contact with
latch plate (7). The latch plate releases the "Set For
Start" button and spring (5) moves it to the RUN position.
This puts the switch in a ready to operate condition.
PRESSURE SWITCH
Pressure switches are are used for several purposes
and are available with different specifications. They are
used in the oil system and in the fuel system. One use of
the switch is to open the circuit between the battery and
the rack shutoff solenoid after the oil pressure is below
the pressure specifications of the switch. It also closes
when the engine starts.
Another use of the switch is to close and activate the
battery charging circuit when the pressure is above the
pressure specification of the switch. It also disconnects
the circuit when the engine is stopped.
Switches
of
this
type
have
three
terminal
connections. They are used to do two operations with
one switch. They open one circuit and close another
with the single switch.
SHUTOFF SOLENOID
A shutoff solenoid changes electrical input into
mechanical output. It is used to move the fuel injection
pump rack to the off position.
The shutoff solenoid can be activated by any one of
the many sources. The most usual are: water
temperature contactor, oil pressure switch, overspeed
switch and remote manual control switch.
RACK SHUTOFF SOLENOID
(Typical Illustration)
WATER TEMPERATURE CONTACTOR SWITCH
The contactor switch for water temperature is
installed in the water manifold. No adjustment to the
temperature range of the contactor can be made. The
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