SHUTOFF AND ALARM SYSTEMS
MECHANICAL OVERSPEED SHUTOFF
1. Shutoff solenoid. 2. Diode assembly. 3. Oil pressure (time delay) or fuel pressure switch. 4. Overspeed switch.
5. Terminal block. 6. Starter. 7. Battery.
The mechanical overspeed switch (4) is fastened to
the tachometer drive on the engine. Wires connect the
switch to the fuel shutoff solenoid. If the speed of the
engine gets too high the overspeed switch sends a signal
to activate shutoff solenoid (I).
The shutoff solenoid is connected to the fuel control
shaft by linkage. When it is activated it will move to stop
the flow of fuel to the engine.
Find and correct the problem that caused the engine
to overspeed. This will help prevent damage to the
After an overspeed shutdown the overspeed switch
must be reset before the engine can start.
Diode assembly (2) is used to stop arcing, for
protection of the system.
The optional grounds to the engine shown are used
with grounded systems only.
An oil pressure (time delay) or fuel pressure switch
(3) is used to prevent discharge of battery (7) through the
solenoid when the engine is stopped.