Introduction
There are two types of electrical protection systems that are available for 3300 Engines:
- Oil Pressure Protection and Water Temperature Protection
- Oil Pressure Protection, Water Temperature Protection and Overspeed Protection
The electric shutoff system is designed to give protection to the engine if there is a problem or a failure in any of the different engine systems. The following engine systems are monitored:
- Engine overspeed
- Starting motor crank terminate
- Engine oil pressure
- Engine coolant temperature
The electric protection system consists of the electronic speed switch and a time delay relay. This system monitors the engine from engine start-up through the rated speed.
Dual Speed Switch (DSS)
The dual speed switch has two controls in a single unit. One control monitors for an engine overspeed. Another control monitors the crank terminate speed.
Engine Overspeed - Engine overspeed protects the engine against damage if the engine runs too fast. Engine overspeed is an adjustable engine speed setting. Normally, 118 percent of the engine's rated speed is the setting for engine overspeed. When the engine overspeeds a switch will close. When the switch closes there will be no power to the fuel solenoid. There will be no fuel to the engine.
Crank Terminate Speed (Starting Motor) - The crank terminate speed protects the starting motor from being damaged when the engine begins to run. The crank terminate speed is an adjustable engine speed setting. When the engine begins to run the engine RPM will reach the crank terminate speed. When the engine RPM reaches the crank terminate speed a switch will open. The open switch will stop the current flow to the starting motor circuit. The starting motor pinion gear will then disengage from the engine flywheel ring gear. The crank terminate speed can also be used to activate the time delay relay.
Time Delay Relay
This relay has special ON/OFF switches with two controls. Depending on the position of the switches, the relay will activate immediately, or the relay will activate after a 9 second delay. The time delay relay is used to arm the shutdown system. Once the time delay relay is activated there is a 70 second delay. The 70 second delay ensures a complete engine shutdown. The 70 second delay prevents damage to the shutoff solenoids.
Water Temperature Contactor Switch
This contactor switch is a separate unit that is mounted in the water manifold. The contactor is wired into the shutdown circuit. The contactor has an element that senses the temperature of the coolant. The contactor must contact the coolant. When the engine coolant temperature becomes too high, a switch closes. When the switch closes the fuel to the engine will be shut off .
Engine Oil Pressure Switch
The Engine Oil Pressure Switch is mounted at the rear of the engine. The engine oil pressure switch senses the pressure of the oil in the oil manifold. The engine oil pressure switch is used to determine low engine oil pressure. The time delay relay will be activated if the engine oil pressure switch senses low engine oil pressure.
Wiring Diagrams
Table 1 gives the correct sizes and color codes.
| Color Code | Total Maximum Recommended Length of the Battery Cable | Wires that are Marked #X | |||
| B-Black | Cable Size | Electric Starting | Output of the Charging Unit | Wire Size | |
| W-White | 12 Volt | 24 to 32 Volt | 0 to 18 amp | #14 | |
| R-Red | 0 | 4.0 ft | 15.0 ft | 19 to 30 amp | #10 |
| O-Orange | 00 | 5.0 ft | 18.0 ft | 31 to 45 amp | #8 |
| BR-Brown | 000 | 6.0 ft | 21.0 ft | 46 to 65 amp | #6 |
| LT GN-Light Green | 0000 | 7.5 ft | 27.0 ft | 66 to 105 amp | #4 |
| PU-Purple | The number that is following the color code is the wire size that is recommended. | ||||
| W/B-White with Black Stripe | |||||
Note: The wires and the cables that are shown with dotted lines are the customer supplied wiring.
| Schematic Reference Notes | |
| Note A: | An optional ground to engine may be used with grounded systems. |
| Note B: | These leads terminate at the starting motor and must be omitted when there is no starting motor. In this case, the customer must provide DC power at the other termination point of these two leads. |
| Note C: | If the 2301A governor is used, only one magnetic pickup is required. Use the magnetic pickup from the overspeed group. Wire the magnetic pickup to the speed switch. Then wire from the speed switch to the 2301A governor. The speed switch may be installed physically near the 2301A if desired. |
| Note D: | An electronic dual speed switch and an electronic time delay relay can be wired to the battery power continuously since the system will draw less than 40 MA of current when the engine is not running. |
| Note E: | If required, the customer should supply a Remote Normal Shutdown Switch (RNS). This requires a single pole normally open (N.O.) switch with a minimum contact rating of 5 amps inductive at the charging system voltage. The switch can be a latching switch if the customer prefers. The switch shuts off fuel to the engine when activated. |
| Note F: | If required, the customer should supply a Remove Emergency Shutdown Switch (RESS). This requires a single pole normally open (N.O.) switch with a minimum contact rating of 5 amps inductive at the charging system voltage. The switch can be a latching switch if the customer prefers. The switch shuts off air and fuel to the engine when activated. This shutoff mode must not be used for normal engine shutdown. |
Note: The Schematic Reference Notes in Table2 are used in the following wiring diagrams.
Water Temperature and Oil Pressure Shutoff System with Time Delay Relay
 | |
| Illustration 1 | g00509966 |
Wiring Diagram (Fuel Shutoff Solenoid Energized to Shutoff) (1) Time delay relay (2) Oil pressure switch (3) Water temperature switch (4) Switch (N.O.) (5) Circuit breaker (6) Shutdown relay (7) Battery (8) Diode assembly (9) Shutdown solenoid (10) Starting motor | |
When the engine starts, the engine oil pressure will begin to rise. The engine oil pressure will close the N.O. contacts in oil pressure switch (2). The engine oil pressure will open the N.C. contacts in oil pressure switch (2). This completes the circuit to time delay relay (1). N.O. contacts (4) in the time delay relay will close. This completes the circuit between shutdown relay (6) and the terminal "TD-7" of the time delay relay.
If the engine coolant temperature goes above the setting of water temperature switch (3), the N.O. contacts in water temperature switch (3) will close. This allows current flow through water temperature switch (3). This also allows current flow through switch (4) to activate shutdown relay (6). Shutdown relay (6) activates fuel shutoff solenoid (9). When the engine stops, engine oil pressure will become less than the setting of the oil pressure switch. The N.O. contacts of the oil pressure switch will open and the flow of current to the time delay relay will stop. This will start the time delay relay timer. After 70 seconds, switch (4) will open. This will stop the current flow through shutdown relay (6). Now, fuel shutoff solenoid (9) will no longer be activated.
If the engine oil pressure is less than the setting of oil pressure switch (2), the N.C. contacts of the oil pressure switch will close. This will allow current flow through switch (4) to activate shutdown relay (6). The shutdown relay will activate fuel shutoff solenoid (9). The N.O. contacts of the oil pressure switch will open. The time delay relay timer will start. The N.O. contacts of delay relay timer (4) will open after 70 seconds. The current flow through shutdown relay (6) will stop. Now, fuel shutoff solenoid (9) will no longer be activated.
| NOTICE |
|---|
In order to help prevent engine damage, correct or repair the problem that caused the engine shutdown before attempting to restart the engine. |
Water Temperature, Oil Pressure and Electronic Overspeed Shutoff System with Time Delay Relay
 | |
| Illustration 2 | g00509967 |
Wiring Diagram (Fuel Shutoff Solenoid Energized To Shutoff) (1) Magnetic pickup (2) Dual speed switch (3) Overspeed switch (4) Crank terminate switch (5) Water temperature switch (6) Oil pressure switch (7) Time delay relay (8) Normally open (N.O.) (9) Shutdown relay (10) Battery (11) Diode assembly (12) Shutoff solenoid (13) Starting motor | |
The engine speed is detected by magnetic pickup (1). As the teeth of the flywheel go through the magnetic lines of force around the magnetic pickup, an AC voltage is produced. Dual speed switch (2) measures the engine speed from the frequency of the voltage.
Time delay relay (7) controls the operation of shutdown relay (9). The shutdown relay controls the operation of fuel shutoff solenoid (12). Time delay relay (7) will keep the fuel shutoff solenoid energized for 70 seconds after a fault condition. This prevents the engine from being started again before the flywheel has stopped rotation.
When the engine begins to run, the engine RPM will reach the crank terminate speed. When the engine RPM reaches the crank terminate speed, the normally open contacts of crank terminate switch (4) will close. This will complete the circuit to time delay relay (7) through terminal TD-2. In approximately 9 seconds N.O. contacts (8) in time delay relay (7) will close and complete the circuit between shutdown relay (9) and terminal TD-7 of the time delay relay. If the engine oil pressure has not activated oil pressure switch (6) within 9 seconds, current will flow through the N.C. contacts in the oil pressure switch and through the now closed N.O. contacts (8) of the time delay relay. The current will then flow to shutdown relay (9). The shutdown relay will activate fuel shutoff solenoid (12). If engine oil pressure activates oil pressure switch (6), the N.O. contacts of the oil pressure switch will close and the N.C. contacts of the oil pressure switch will open. This will allow current flow to terminal TD-1 of the time delay relay and immediately close N.O. contacts of the time delay relay (8). At the same time, N.C. contacts in the oil pressure switch will open. This will prevent current flow to contacts of the time delay relay (8) .
If the engine speed increases above the overspeed setting (118 percent of rated speed) of the dual speed switch, the overspeed switch (part of the dual speed switch) will close across terminals DSS-7 and DSS-8. This completes the circuit to shutdown relay (6) through the now closed contacts of the time delay relay (8) at terminal TD-7. Shutdown relay (9) is activated. The shutdown relay will activate fuel shutoff solenoid (12). This will cause the engine to shutdown.
When the engine speed is less than the cranking speed setting, contacts on the DSS (4) will open. This stops the flow of current to terminal TD-2 of the time delay relay. When the engine stops, engine oil pressure will become less than the setting of the oil pressure switch. The N.O. contacts of the oil pressure switch will open. This will stop the flow of current to terminal TD-1 of the time delay relay. This will start the time delay relay timer. After 70 seconds, the N.O. contacts of the time delay relay (8) will open and stop current flow to shutdown relay (9). Fuel shutoff solenoid (12) will no longer be activated.
| NOTICE |
|---|
In order to help prevent engine damage, correct or repair the problem that caused the engine shutdown before attempting to restart the engine. |
After an overspeed shutdown, a button on the dual speed switch must be pushed. Depressing the button will open the overspeed switch so the engine can be ran.
When the engine has been started and the engine is running, the N.O. contacts of time delay relay (8) will close. If the engine coolant temperature rises above the setting of water temperature switch (5), the N.O. contacts of the water temperature switch will close. This allows the current flow through the water temperature switch and through the closed contacts of time delay relay (8). Shutdown relay (9) will activate fuel shutoff solenoid (12) .
When the engine speed is less than the cranking speed setting, contacts on the DSS (4) will open. This will stop the flow of current to terminal TD-2 of the time delay relay. When the engine stops, the engine oil pressure will be less than the setting of the oil pressure switch. The N.O. contacts of the oil pressure switch will open. This will stop the flow of current to terminal TD-1 of the time delay relay. This will start the time delay relay timer. After 70 seconds, N.O. contacts of time delay relay (8) will open and stop current flow to shutdown relay (9). Fuel shutoff solenoid (12) will no longer be activated.
| NOTICE |
|---|
In order to help prevent engine damage, correct or repair the problem that caused the engine shutdown before attempting to restart the engine. |
When the engine has been started and the engine is running, N.O. contacts of the time delay relay (8) will close. If the engine oil pressure is less than the setting of oil pressure switch (6), the N.C. contacts of the oil pressure switch will close. This will allow current flow through the closed contacts of time delay relay (8). The shutdown relay (9) will activate fuel shutoff solenoid (12). The N.O. contacts of the oil pressure switch will also open and stop current flow to terminal TD-1 of the time delay relay. When the engine speed is less than the cranking speed setting, N.O. contacts on the DSS (4) will open. This stops the flow of current to terminal TD-2 of the time delay relay and starts the time delay relay timer. After 70 seconds, switch (8) will open and stop current flow to shutdown relay (9). Fuel shutoff solenoid (12) will no longer be activated.
| NOTICE |
|---|
In order to help prevent engine damage, correct or repair the problem that caused the engine shutdown before attempting to restart the engine. |
Electronic Overspeed Shutoff System with Time Delay Relay
 | |
| Illustration 3 | g00510010 |
Wiring Diagram (Fuel Shutoff Solenoid Energized to Shutoff) (1) Magnetic pickup (2) Crank terminate switch (3) Dual speed switch (4) Time delay relay (5) Normally open (N.O.) switch (6) Shutdown relay (7) Battery (8) Diode assembly (9) Shutoff solenoid (10) Starting motor | |
The engine speed is detected by magnetic pickup (1). As the teeth of the flywheel go through the magnetic lines of force around the pickup, an AC voltage is produced. Dual speed switch (3) measures engine speed from the frequency of the voltage.
Time delay relay (4) controls the operation of shutdown relay (6). The shutdown relay controls the operation of fuel shutoff solenoid (9). Time delay relay (4) will keep the fuel shutoff solenoid energized for 70 seconds after a fault condition. This prevents the engine from being started again before the flywheel has stopped rotation.
When the engine begins to run, the engine RPM will reach the crank terminate speed. When the engine RPM reaches the crank terminate speed, the normally open contacts of crank terminate switch (2) [which is part of dual speed switch (3) ] will close. This will complete the circuit to time delay relay (4) through terminal TD-1. Normally open contacts (5) in time delay relay (4) now close and complete the circuit between shutdown relay (6) and terminal TD-7.
If the engine speed increases above the overspeed setting (118 percent of rated speed) of the dual speed switch, the overspeed switch (part of the dual speed switch) will close across terminals DSS-7 and DSS-8. This completes the circuit to shutdown relay (6) through the now closed contacts (5) of the time delay relay at terminal TD-7. Shutdown relay (6) is activated. The shutdown relay will activate fuel shutoff solenoid (9). This will cause the engine to shutdown.
When the engine stops, crank terminate switch (2) will open the circuit across terminals DSS-10 and DSS-11. This stops current flow to time delay relay (4). The time delay relay timer will start. 70 seconds later, switch (5) will open the circuit at terminal TD-7. Current flow is then stopped through shutdown relay (6). Fuel shutoff solenoid (9) will no longer be activated.
A reset button on the dual speed switch must be pushed in order to open the overspeed switch. The reset button must be pushed before the engine can run.
| NOTICE |
|---|
In order to help prevent engine damage, correct or repair the problem that caused the engine shutdown before attempting to restart the engine. |
Water Temperature and Oil Pressure Shutoff with Time Delay Relay (Fuel Shutoff Solenoid Energized to Run)
 | |
| Illustration 4 | g00510019 |
Wiring Diagram (1) Time delay relay (2) Water temperature switch (3) Oil pressure switch (4) Switch (N.C.) (5) Fuel shutoff solenoid | |
When terminal 4 of the time delay relay is supplied with an electrical current, the current will also flow to oil pressure switch (3) and to terminal 6 of time delay relay (1). From terminal 6 of time delay relay (1) the current flows through N.C. contacts (4) of the time delay relay (1). The fuel shutoff solenoid will be energized. When fuel shutoff solenoid (5) is energized, the engine will be able to start.
When the engine starts, the engine oil pressure will close the N.O. contacts in the oil pressure switch (3). This completes the circuit to time delay relay (1), water temperature switch (2) and fuel shutoff solenoid (5). N.C. contacts (4) in the time delay relay now open and break the circuit between fuel shutoff solenoid (5) and terminal six of the time delay relay.
If the engine coolant temperature goes above the setting of water temperature switch (2), the N.C. contacts will open. This stops current flow through water temperature switch (2). There will be no current flow through contacts (4) of the time delay relay. The fuel shutoff solenoid will not be energized. When the engine stops, engine oil pressure will become less than the setting of the oil pressure switch. The N.O. switch will open and stop the flow of current to the time delay relay. This will start the time delay relay timer. After 70 seconds, contacts (4) of the time delay relay will close and current will again flow to the fuel shutoff solenoid.
 | |
| Illustration 5 | g00510075 |
Wiring Schematic (Water Temperature and Oil Pressure Shutoff) (BAT) Battery (CB) Circuit breaker (OPS) Oil pressure switch (PS) Pinion solenoid (SM) Starting Motor (SPB) Start push button (SS) Shutoff solenoid (TDR) Time delay relay (VTS) Voltage transient suppressor (WTS) Water temperature switch | |
If engine oil pressure is below the setting of the oil pressure switch, the N.O. contacts of the oil pressure switch will open. This will stop current flow through contacts (4) of the time delay relay. The fuel shutoff solenoid will not be energized. The current flow will stop to the time delay relay and start the time delay relay timer. After 70 seconds, contacts (4) of the time delay relay will close and current will again flow through the fuel shutoff solenoid.
| NOTICE |
|---|
In order to help prevent engine damage, correct or repair the problem that caused the engine shutdown before attempting to restart the engine. |
Note: To help prevent discharge of the batteries when the engine is shut off, a switch can be installed to turn off the current to the shutoff solenoid.
Water Temperature, Oil Pressure and Electronic Overspeed Shutoff with Time Delay Relay (Fuel Shutoff Solenoid Energized to Run)
 | |
| Illustration 6 | g00510077 |
Wiring Diagram (1) Magnetic pickup (2) Dual speed switch (3) Overspeed switch (N.C.) (4) Cranking speed switch (N.O.) (5) Water temperature switch (6) Oil pressure switch (7) Time delay relay (8) Switch (N.C.) (9) Fuel shutoff solenoid | |
The engine speed is detected by magnetic pickup (1). As the teeth of the flywheel go through the magnetic lines of force around the pickup, an AC voltage is produced. Dual speed switch (2) determines the engine speed from the frequency of the voltage.
Time delay relay (7) controls the operation of fuel shutoff solenoid (9). To prevent the engine from restarting, the time delay relay turns off the current to the fuel shutoff solenoid for approximately 70 seconds after the engine stops.
When the electrical current is turned on to the time delay relay terminal 4, the current then goes to terminals 6 and 11 of the dual speed switch and to terminal 1 of oil pressure switch (6). Current also flows to terminal 6 of the time delay relay and through N.C. contacts of the time delay relay (8). The fuel shutoff solenoid (9) will be energized. The engine will be able to start.
When the engine begins to run, the engine RPM will reach the crank terminate speed. When the engine RPM reaches the crank terminate speed, the N.O. contacts of the cranking speed switch (4) in the cranking circuit of the dual speed switch will close. This completes the circuit to terminal 2 of the time delay relay. In approximately 9 seconds N.C. contacts (8) of the time delay relay will open and break the circuit between the fuel shutoff solenoid and terminal 6 of the time delay relay. If the engine oil pressure has not closed the contacts of the oil pressure switch (6) within 9 seconds, N.C. contacts (8) of the time delay relay will open and break the circuit to fuel shutoff solenoid (9). This will cause the engine to shutdown. However, if the engine oil pressure closes the N.O. contacts in oil pressure switch (6), current will flow through water temperature switch (5), overspeed switch (3) and terminal 5 of the time delay relay. The fuel shutoff solenoid will be energized. Current will also flow to terminal 1 of the time delay relay. This will immediately open N.C. contacts (8) of the time delay relay.
If the engine RPM rises higher than the setting of the overspeed switch, N.C. contacts (3) of the dual speed switch will open. This will stop the current flow to the fuel shutoff solenoid. The engine will shut down.
When the engine RPM is less than the crank speed setting, crank speed contacts (4) of the dual speed switch will open. This will stop the flow of current to terminal 2 of the time delay relay. When the engine stops, the engine oil pressure will become less than the setting of the oil pressure switch. The N.O. contacts of the oil pressure switch will open and stop the flow of current to terminal 1 of the time delay relay. This will start the time delay relay timer. After 70 seconds, contacts (8) of the time delay relay will close and again allow current flow to the fuel shutoff solenoid.
| NOTICE |
|---|
In order to help prevent engine damage, correct or repair the problem that caused the engine shutdown before attempting to restart the engine. |
After an overspeed shutdown, the overspeed switch must be reset.
When the engine has been started and the engine is running, the time delay relay will open contacts (8). If the engine coolant temperature rises above the setting of water temperature switch (5), the N.C. contacts of the temperature switch will open. This will stop the current flow through the water temperature switch and through overspeed switch (3). The fuel shutoff solenoid will not be energized. The engine will shut down.
When the engine RPM is less than the cranking speed setting, crank speed contacts (4) of the dual speed switch will open. This will stop the flow of current to terminal 2 of the time delay relay. When the engine stops, engine oil pressure will become less than the setting of the oil pressure switch. The N.O. contacts of the oil pressure switch will open and stop the flow of current to terminal 1 of the time delay relay. This will start the time delay relay timer. After 70 seconds, contacts (8) of the time delay relay will close and again allow current flow to the fuel shutoff solenoid.
| NOTICE |
|---|
In order to help prevent engine damage, correct or repair the problem that caused the engine shutdown before attempting to restart the engine. |
When the engine has been started and the engine is running, the time delay relay will close contacts (8) of the time delay relay. If the engine oil pressure is less than the setting of oil pressure switch (6), the N.O. contacts of the oil pressure switch will open. This will stop current flow through overspeed switch (3). The fuel shutoff will not be energized. The engine will shut down. The current flow will also stop to terminal 1 of the time delay relay. When the engine RPM is less than the cranking speed setting, crank speed contacts (4) of the dual speed switch will open. This will stop the flow of current to terminal 2 of the time delay relay and starts the time delay relay timer. After 70 seconds, contacts (8) of the time delay relay will close and again allow current flow to the fuel shutoff solenoid.
| NOTICE |
|---|
In order to help prevent engine damage, correct or repair the problem that caused the engine shutdown before attempting to restart the engine. |
Note: To help prevent discharge of the batteries when the engine is shut off, a switch can be installed to turn off the current to the shutoff solenoid.
 | |
| Illustration 7 | g00510309 |
Wiring Schematic (Water Temperature and Oil Pressure Shutoff (BAT) Battery (CB) Circuit breaker (OPS) Oil pressure switch (PS) Pinion solenoid (SM) Starting Motor (SPB) Start push button (SS) Shutoff solenoid (TDR) Time delay relay (VTS) Voltage transient suppressor (WTS) Water temperature switch | |
Alarm Contactor System
 | |
| Illustration 8 | g00510319 |
Wiring Diagram (1) Oil pressure switch (2) Water temperature contactor (3) Source voltage (4) Toggle switch (if equipped) (5) Alarm (6) Signal lights | |
If the oil pressure is too low or the water temperature is too high this system will activate alarm (5) and signal lights (6).
| NOTICE |
|---|
When an alarm is activated, corrective measures must be taken before the situation becomes an emergency in order to avoid possible engine damage. |
Before the engine is started it will be necessary to override oil pressure switch (1) or the alarm will activate. This is done by either a manual override button on the (earlier) oil pressure switch or toggle switch (4). When the engine starts, the engine oil pressure will return the manual override button to the run position. The toggle switch must be manually closed when the engine starts and the oil pressure rises.
 | |
| Illustration 9 | g00510383 |
Wiring Diagram (1) Oil pressure switch (2) Water temperature contactor (3) Source voltage (4) Toggle switch (if equipped) (6) Signal lights (three) (7) Air temperature contactor | |
If the oil pressure is too low or the water temperature is too high this system will activate alarm (5) and signal lights (6).
| NOTICE |
|---|
When an alarm is activated, corrective measures must be taken before the situation becomes an emergency in order to avoid possible engine damage. |
Before the engine is started it will be necessary to override oil pressure switch (1) or the alarm will activate. This is done by either a manual override button on the (earlier) oil pressure switch or toggle switch (4). When the engine starts, the engine oil pressure will return the manual override button to the run position. The toggle switch must be manually closed when the engine starts and the oil pressure rises.
 | |
| Illustration 10 | g00510410 |
Wiring Diagram (1) Oil pressure switch (2) Water temperature contactor (3) Source voltage (4) Toggle switch (if equipped) (5) Alarm (7) Air temperature contactor | |
If the oil pressure is too low or the water temperature is too high this system will activate alarm (5) and signal lights (6).
| NOTICE |
|---|
When an alarm is activated, corrective measures must be taken before the situation becomes an emergency in order to avoid possible engine damage. |
Before the engine is started it will be necessary to override oil pressure switch (1) or the alarm will activate. This is done by either a manual override button on the (earlier) oil pressure switch or toggle switch (4). When the engine starts, the engine oil pressure will return the manual override button to the run position. The toggle switch must be manually closed when the engine starts and the oil pressure rises.
Water Temperature and Oil Pressure Shutoff with Time Delay Relay (With Oil Pressure Delay or Fuel Pressure Switch)
 | |
| Illustration 11 | g00510423 |
Wiring Diagram (1) Oil pressure switch (2) Water temperature contactor (3) Oil pressure (time delay) or fuel pressure switch (4) Rack solenoid (5) Diode assembly (6) Starting motor (7) Battery | |
If the oil pressure is too low or the coolant temperature is too high this system will activate rack solenoid (4) The solenoid 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 engine will stop.
| NOTICE |
|---|
In order to help prevent engine damage, correct or repair the problem that caused the engine shutdown before attempting to restart the engine. |
Before the engine can be started it will be necessary to push the manual override button on (earlier) oil pressure switch (1). When the engine starts, the engine oil pressure will return the manual override button to the run position.
Diode assembly (5) is used to stop arcing, for protection of the system.
Oil pressure or fuel pressure switch (3) is used to prevent discharge of battery (7) through the solenoid when the engine is stopped.
Electronic Overspeed Shutoff System (With Oil Pressure Delay or Fuel Pressure Switch)
 | |
| Illustration 12 | g00510474 |
Wiring Diagram (1) Rack solenoid (2) Oil pressure (time delay) or fuel pressure switch (3) Dual speed switch (4) Magnetic pickup (5) Diode assembly (6) Starting motor (7) Battery | |
The engine speed is detected by magnetic pickup (4). As the teeth of the flywheel go through the magnetic lines of force around the pickup, an AC voltage is produced. Dual speed switch (3) measures the engine speed from the frequency of this AC voltage.
Rack solenoid (1) is connected to the fuel rack by linkage. When it is activated, it will move to stop the flow of fuel to the engine.
If the engine speed increases above the overspeed setting (118 percent of rated speed) of the dual speed switch, the overspeed switch [which is part of dual speed switch (3) ] will close across terminals DSS-7 and DSS-8. This completes the circuit to rack solenoid (1) through the now closed oil pressure or fuel pressure switch (2) and activates the solenoid to shutdown the engine.
| NOTICE |
|---|
In order to help prevent engine damage, correct or repair the problem that caused the engine shutdown before attempting to restart the engine. |
After an overspeed shutdown, a button on the dual speed switch, must be pushed to open the overspeed switch before the engine can be started.
Diode assembly (5) is used to stop arcing, for protection of the system.
An oil pressure or fuel pressure switch (2) is used to prevent discharge of battery (7) 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.
Water Temperature, Oil Pressure and Electronic Overspeed Shutoff with Time Delay Relay (With Oil Pressure Delay or Fuel Pressure Switch)
 | |
| Illustration 13 | g00510475 |
Wiring Diagram (1) Oil pressure switch (2) Oil pressure (time delay) or fuel pressure switch (3) Water temperature contactor (4) Dual speed switch (5) Magnetic pickup (6) Rack Solenoid (7) Diode assembly (8) Starting motor (9) Battery | |
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, the contacts of the oil pressure switch (1) or water temperature switch (3) will close to complete the circuit and activate rack solenoid (6).
| NOTICE |
|---|
In order to help prevent engine damage, correct or repair the problem that caused the engine shutdown before attempting to restart the engine. |
The engine speed is detected by magnetic pickup (5). As the teeth of the flywheel go through the magnetic lines of force around the pickup, an AC voltage is produced. Dual speed switch (4) measures the engine speed from the frequency of this AC voltage.
If the engine RPM increases above the overspeed setting (118 percent 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 oil pressure or fuel pressure switch (2) and water temperature contactor (3) to activate the solenoid and shutdown the engine.
| NOTICE |
|---|
In order to help prevent engine damage, correct or repair the problem that caused the engine shutdown before attempting to restart the engine. |
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.
Mechanical Overspeed Shutoff (Fuel Shutoff Solenoid Energized to Run)
 | |
| Illustration 14 | g00510476 |
Wiring Diagram (1) Overspeed switch (2) Shutoff solenoid | |
The mechanical overspeed switch (1) is mounted to the tachometer drive on the engine. If there is an engine overspeed the N.C. contacts in overspeed switch (1) will open and break the electrical circuit to shutoff solenoid (2) causing engine shutdown.
| NOTICE |
|---|
In order to help prevent engine damage, correct or repair the problem that caused the engine shutdown before attempting to restart the engine. |
After an overspeed shutdown, the overspeed switch must be reset.
 | |
| Illustration 15 | g00510478 |
Wiring Schematic (BAT) Battery (CB) Circuit breaker (OSS) Overspeed switch (PS) Pinion solenoid (RNS) Remote normal shutdown switch (SPB) Start push button (SM) Starting motor (SS) Shutoff solenoid (TDR) Time delay relay (VTS) Voltage transient suppressor | |
Water Temperature, Oil Pressure and Mechanical Overspeed Shutoff with Time Delay Relay (Fuel Shutoff Solenoid Energized to Run)
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| Illustration 16 | g00572683 |
Wiring Diagram (1) Overspeed switch (N.C.) (2) Water temperature switch (3) Oil pressure switch (4) Time delay relay (5) Switch (N.C.) (6) Fuel shutoff solenoid | |
The engine speed is monitored by the mechanical overspeed switch (1) .
Time delay relay (4) controls the operation of fuel shutoff solenoid (6). To prevent the engine from restarting, the time delay relay turns off the current to the fuel shutoff solenoid for approximately 70 seconds after the engine stops.
When there is an electrical current to time delay relay terminal 4, current will also be present at terminal 1 of oil pressure switch (3). Current also flows to terminal 6 of the time delay relay and through N.C. contacts (5) of the time delay relay to energize fuel shutoff solenoid (6). This will allow the engine to start.
After the engine is started, engine oil pressure closes the N.O. contacts in oil pressure switch (3). Current will flow through water temperature switch (2), overspeed switch (1) and terminal 5 of the time delay relay to the shutoff solenoid. Current also flows to terminal 1 of the time delay relay. This will immediately open N.C. contacts (5) of the time delay relay.
If the engine RPM reaches more than the setting of the overspeed switch, the N.C. contacts of overspeed switch (1) will open. This will stop the current flow to the fuel shutoff solenoid and will cause the engine to shutdown.
When the engine stops, the engine oil pressure will become less than the setting of the oil pressure switch. The N.O. contacts of the oil pressure switch will open and stop the flow of current to terminal 1 of the time delay relay. This will start the time delay relay timer. After 70 seconds, switch (5) will close and again allow current flow to the fuel shutoff solenoid.
| NOTICE |
|---|
In order to help prevent engine damage, correct or repair the problem that caused the engine shutdown before attempting to restart the engine. |
After an overspeed shutdown, the overspeed switch must be reset.
When the engine has been started and the engine is running, the time delay relay will open contacts (5) of the time delay relay. If the engine coolant temperature rises above the setting of water temperature switch (2), the N.C. contacts of the water temperature switch will open. This will stop the current flow through the water temperature switch and through overspeed switch (1). The fuel shutoff solenoid will not be energized. The engine will shut down. When the engine stops, engine oil pressure will become less than the setting of the oil pressure switch. The N.O. contacts in the oil pressure switch will open and stop the flow of current to terminal 1 of the time delay relay. This will start the time delay relay timer. After 70 seconds, switch (5) will close and again allow current flow to the fuel shutoff solenoid.
| NOTICE |
|---|
In order to help prevent engine damage, correct or repair the problem that caused the engine shutdown before attempting to restart the engine. |
When the engine has been started and the engine is running, contacts (5) of the time delay relay will close. If the engine oil pressure is less than the setting of oil pressure switch (3), the N.O. contacts of the oil pressure switch will open. This will stop the current flow through switch (1). The fuel shutoff solenoid will not be energized. The engine will shut down. When the engine stops, the engine oil pressure will become less than the setting of the oil pressure switch. The N.O. contacts of the oil pressure switch will open and stop the flow of current to terminal 1 of the time delay relay. This will start the time delay relay timer. After 70 seconds, switch (5) will close and again allow current flow to the fuel shutoff solenoid.
| NOTICE |
|---|
In order to help prevent engine damage, correct or repair the problem that caused the engine shutdown before attempting to restart the engine. |
Note: To help prevent discharge of the batteries when the engine is shut off, a switch can be installed to turn off the current to the shutoff solenoid.
 | |
| Illustration 17 | g00510624 |
Wiring Schematic (Water Temperature, Oil Pressure and Overspeed Shutoff) (BAT) Battery (CB) Circuit breaker (CT) Crank terminate (D) Diode (OPS) Oil pressure switch (OSS) Overspeed switch (PS) Pinion solenoid (SPB) Start push button (SS) Shutoff solenoid (TDR) Time delay relay (VTS) Voltage transient suppressor (WTS) Water temperature switch | |
Water Temperature, Oil Pressure and Mechanical Overspeed Shutoff with Time Delay Relay (Fuel Shutoff Solenoid Energized to Shutoff)
 | |
| Illustration 18 | g00572507 |
Wiring Diagram (1) Time delay relay (2) Overspeed switch (N.O.) (3) Water temperature switch (4) Oil pressure switch (5) Switch (N.O.) (6) Fuel shutoff solenoid | |
The engine speed is monitored by the mechanical overspeed switch (2) .
Time delay relay (1) controls the operation of fuel shutoff solenoid (6). To prevent damage to the fuel shutoff solenoid, the time delay relay turns off the current approximately 70 seconds after the engine stops.
After the engine is started, the engine oil pressure activates oil pressure switch (4), the N.O. contacts of the oil pressure switch will close. The N.C. contacts of the oil pressure switch will open. This will allow current flow to terminal 1 of the time delay relay and immediately close N.O. contacts (5) of the time delay relay. The N.C. contacts in the oil pressure switch are already open and prevent current flow to contacts (5) of the time delay relay.
If the engine RPM rises above the setting of the overspeed switch, the N.O. contacts of the engine overspeed switch (2) will close. The engine is running, so the contacts (5) of the time delay are already closed. When the N.O. contacts of the engine overspeed switch (2) close, the fuel shutoff solenoid is activated. The engine will shut down. When the engine stops, the engine oil pressure will become less than the setting of the oil pressure switch. The N.O. contacts of the oil pressure switch will open and stop the flow of current to terminal one of the time delay relay. This will start the time delay relay timer. After 70 seconds, N.O. contacts (5) of the time delay relay will open and stop the current flow to the fuel shutoff solenoid.
| NOTICE |
|---|
In order to help prevent engine damage, correct or repair the problem that caused the engine shutdown before attempting to restart the engine. |
After an overspeed shutdown, the overspeed switch must be reset.
When the engine has been started and the engine is running, the time delay relay will close N.O. contacts (5) of the time delay relay. If the engine coolant temperature rises above the setting of water temperature switch (3), the N.O. contacts of the water temperature switch will close. This will allow the current flow through the water temperature switch and through the closed contacts (5) of the time delay relay. The fuel shutoff solenoid will be activated. The engine will shut down.
When the engine stops, engine oil pressure will become less than the setting of the oil pressure switch. The N.O. contacts of the oil pressure switch will open and stop the flow of current to terminal 1 of the time delay relay. This will start the time delay relay timer. After 70 seconds, N.O. contacts (5) of the time delay relay will open and stop current flow to the fuel shutoff solenoid.
| NOTICE |
|---|
In order to help prevent engine damage, correct or repair the problem that caused the engine shutdown before attempting to restart the engine. |
When the engine has been started and the engine is running, the time delay relay will close N.O. contacts (5) of the time delay relay. If the engine oil pressure is less than the setting of oil pressure switch (4), the N.C. contacts of the oil pressure switch will close. This will allow the current flow through closed contacts (5) of the time delay relay. The fuel shutoff solenoid will be activated. The engine will shut down.
When the engine stops, engine oil pressure will become less than the setting of the oil pressure switch. The N.O. contacts of the oil pressure switch will open and stop the flow of current to terminal 1 of the time delay relay. This will start the time delay relay timer. After 70 seconds, N.O. contacts (5) of the time delay relay will open and stop current flow to the fuel shutoff solenoid.
| NOTICE |
|---|
In order to help prevent engine damage, correct or repair the problem that caused the engine shutdown before attempting to restart the engine. |
 | |
| Illustration 19 | g00510949 |
Wiring Schematic (Water Temperature, Oil Pressure and Overspeed Shutoff) (BAT) Battery (CB) Circuit breaker (CT) Crank terminate (D) Diode (OPS) Oil pressure switch (OSS) Overspeed switch (PS) Pinion solenoid (SPB) Start push button (SM) Starting motor (SS) Shutoff solenoid (TDR) Time delay relay (VTS) Voltage transient suppressor (WTS) Water temperature switch | |
Oil Pressure Switch
Micro Switch Type
The oil pressure switch is used to give protection to the engine from damage due to low oil pressure. When oil pressure lowers to the pressure specifications of the switch, the switch will close. The closed switch will activate 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 the pressure of the oil in the bellows becomes higher, the arm is moved against the force of a spring. When the projection of the arm makes contact with the arm, the oil pressure in the bellows will move both arms. This also moves the button of the microswitch to activate the microswitch.
Some of these switches have a "Set For Start" button. When the button is pushed in, the microswitch is in the START position. This is done because the latch plate holds the arm against the button of the microswitch. The switch will operate as if the oil pressure was normal. When the engine is started, pressurized oil flows into the bellows. The bellows move the arm into contact with the latch plate. The latch plate releases the "Set For Start" button and the spring moves it to the RUN position. This puts the switch in a ready to operate condition.
Pressure Switch
Pressure switches are used for several purposes and are available with different specifications. Pressure switches 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. The switch 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. The switch also disconnects the circuit when the engine is stopped.
Shutoff Solenoid
A shutoff solenoid changes electrical input into mechanical output. The shutoff solenoid is used to move the fuel injection pump rack to the off position.
The shutoff solenoid can be activated by any one of many sources. The normal sources are: water temperature switch, oil pressure switch, overspeed switch and remote manual control switch.
The shutoff solenoid can be either the energized to run or the energized to shutoff type as provided with the engine shutoff control logic.
Water Temperature Switch
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| Illustration 20 | g00510066 |
Typical water temperature switch | |
The water temperature switch is installed in the water manifold. No adjustment to the temperature range of the water temperature switch can be made. The element senses the temperature of the coolant and then operates a microswitch when the coolant temperature is too high. If the reason for the engine overheating is because of low coolant level or no coolant, the switch will not operate. The water temperature switch element must be in contact with the coolant to operate correctly.
The water temperature switch is connected to the rack shutoff solenoid. The engine can be shut down if the water temperature switch detects a high coolant temperature. The switch can also be connected to an alarm system. When the temperature of the coolant lowers to the operating range, the microswitch will open automatically.
Circuit Breaker
A circuit breaker provides overload protection to an electrical circuit. Circuit breakers are rated by the amount of current that the circuit breaker will permit to flow. If the amount of current in a circuit gets too high it will cause heat in a disc in the circuit breaker. The heat will cause distortion of the disc and the contacts will open. When the contacts open, no current will flow through the circuit.
| NOTICE |
|---|
Find and correct the problem that caused the circuit breaker to open. This will help prevent damage to the circuit components from too much current. |
An open circuit breaker will close (reset) automatically when it becomes cooler.
Mechanical Overspeed Switch
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| Illustration 21 | g00510068 |
Typical mechanical overspeed switch (1) Button (2) Lock screw | |
The overspeed switch is installed on the tachometer drive shaft of the fuel injection pump. The switch activates when the engine speed is equal to the overspeed setting. Once the overspeed switch has been activated, the contacts will not automatically return to the normal position. The reset button (1) must be pushed by the operator to make the switch contacts return to the normal position. The usual setting for the overspeed switch is 18 percent higher than the rated speed of the engine.
Some overspeed switches also have under speed contacts. The contacts for underspeed will close at approximately 600 rpm as the engine speed increases. The under speed setting is not adjustable.