Systems Operation

Usage:

Introduction

NOTE: For Specifications with illustrations, make reference to Specifications For 3408 & 3412 Natural Gas Engine Attachments, Form No. SENR3089. If the Specifications in Form SENR3089 are not the same as in the Systems Operation and Testing And Adjusting, look at the printing date on the back cover of each book. Use the Specifications given in the book with the latest date.

Power Take-Off Clutches

Power Take-Off Clutch (Typical Illustration)
(1) Ring (2) Driven discs (3) Link assemblies (4) Lever (5) Key (6) Collar assembly (7) Nut (8) Yoke assembly (9) Hub (10) Plates (11) Output shaft

Power take-off clutches (PTO's) are used to send power from the engine to accessory components. For example, a PTO can be used to drive an air compressor or a water pump.

The PTO is driven by a ring (1) that has spline teeth around the inside diameter. The ring can be connected to the front or rear of the engine crankshaft by an adapter.

NOTE: On some PTO's located at the rear of the engine, ring (1) is a part of the flywheel.

The spline teeth on the ring engage with the spline teeth on the outside diameter of driven discs (2). When lever (4) is moved to the ENGAGED position, yoke assembly (8) moves collar assembly (6) in the direction of the engine. The collar assembly is connected to four link assemblies (3). The action of the link assemblies will hold the faces of driven discs (2), drive plates (10) and hub (9) tight together. Friction between these faces permits the flow of torque from ring (1), through driven discs (2), to plates (10) and hub (9). Spline teeth on the inside diameter of the plates drive the hub. The hub is held in position on the output shaft (11) by a taper, nut (7) and key (5).

NOTE: A PTO can have from one to three driven discs (2) with a respective number of plates.

When lever (4) is moved to the NOT ENGAGED position, yoke assembly (8) moves collar assembly (6) to the left. The movement of the collar assembly will release link assemblies (3). With the link assemblies released there will not be enough friction between the faces of the clutch assembly to permit a flow of torque.

Electrical System

Three electrical systems are available to provide engine protection. In each case, engine shutoff is achieved by grounding the magneto. Each system is also capable of activating the gas shutoff valve if provided.

1. For the self-powered protection system, oil pressure (OP) and water temperature (WT) protection are provided. When combined with a mechanical overspeed contactor switch (MOS), full protection is obtained. An energized-to-shutoff (ETS) gas shutoff valve (GSOV) is available which is activated by magneto voltage.

2. An energized-to-run (ETR) non-auto-start-stop protection system provides OP, WT and OS (overspeed) protection. An electronic speed switch (ESS) is used for the OS protection. This system is fully independent and requires an external 24 volt power source and an energized-to-run (ETR) gas shut-off valve.

3. The ETR auto-start-stop protection system is the same as system #2 above except it is not fully independent. An auto start-stop cranking panel must be wired into the system (by the customer) to provide starting and stopping logic.

Electrical Schematics And Wiring Diagrams

Electrical schematic foldouts are provided in this section with the text for each protection system. Use the electrical schematics to follow the circuit operations of the protection systems.

Point-to-point wiring diagrams for the protection systems, junction boxes, and starting, charging, and tachometer circuits are located in the Wiring Diagrams Section of this module. Use the diagrams for component position layout.

Components

The components that follow may be used on one or more of the three protection systems available on the 3408 and 3412 spark ignited engines.

Water Temperature Sending Unit (WTSU)

Sending Unit for Water Temperature
(1) Connection (2) Bushing (3) Bulb

The sending unit for water temperature is an electrical resistance. It changes the value of its resistance according to the temperature which the bulb (3) feels.

The sending unit is in a series circuit with the electrical gauge. When the temperature is high, the resistance is high. This makes the gauge have a high reading.

The sending unit must be in contact with the coolant. If the coolant level is too low because of a sudden loss of coolant while the engine is running or because the level is too low before starting the engine, the sending unit will not work correctly.

This sending unit requires 24VDC electrical input, therefore, it is only used with the energized-to-run protection systems.

Oil Pressure Sending Unit (OPSU)

Sending Unit for Oil Pressure (Typical Example)
(1) Connection (2) Fitting

The sending unit for oil pressure is an electrical, resistance. It has a material which changes electrical resistance according to pressure which it feels.

The sending unit for oil pressure is in a series circuit with the electrical gauge. As the pressure on the sending unit changes, the reading on the gauge changes in the same way.

This sending unit requires 24VDC electrical input, therefore, it is only used with the energized-to-run protection systems.

Electric Service Meter

The electric service meter group is self-powered. A magnetic pickup mounted on the flywheel housing provides voltage (starting at 200 engine rpm) to power the electric service meter which records clock hours with quartz accuracy. A separate magnetic pickup must be used for each service meter; it cannot be shared with the digital tachometer, electronic speed switch, or electronic governor magnetic pickup.

Water Temperature Contactor Switch (WTS)

A water temperature contactor switch is located in the cooling system. The unit is nonadjustable. Thermal expansion of the element operates a micro-switch that signals the shutoff solenoid which causes engine shutdown. The water temperature element must be in contact with the coolant. If overheating occurs due to low coolant level or not coolant, the sending unit will not function.

The water temperature sending unit can also be wired into an alarm system or light to signal high water temperature. After an overheated engine is allowed to cool, the contactor automatically resets itself.

Contactor Switch (Water Temperature)

Magnetic Pickup (MPU)

Magnetic Pickup
(1) Clearance dimension (2) Magnetic pickup (3) Wires (4) Locknut (5) Gear tooth (6) Housing

The magnetic pickup is a single pole, permanent magnet generator made of wire coils around a permanent magnet pole piece. As the teeth of the flywheel ring gear go through the magnetic lines of force around the pickup, an AC voltage is made. A positive voltage is made when each tooth goes by the pole piece. Each time the space between the teeth goes by the pole piece, a negative voltage is made. Engine speed is then determined by the frequency of these signals.

Overspeed Contactor Switch (MOS)

The overspeed contactor is used in a self powered protection system to protect the engine from damage due to overspeeding. It contains a micro switch that is activated by high engine speed. The overspeed switch is mounted on the tachometer drive. If the engine overspeeds, the switch contacts close and connect the magneto to ground to shut down the engine. When the engine shuts down because of overspeeding, the overspeed contactor switch must be reset by pushing reset button (1). The overspeed contactor switch is adjustable.

Overspeed Contactor
(1) Reset button

Circuit Breaker (CB)

The circuit breaker is a switch that opens the battery circuit if the current in the electrical system goes higher than the rating of the circuit breaker.

A heat activated metal disc with a contact point completes the electric circuit through the circuit breaker. If the current in the electrical system gets too high, it causes the metal disc to get hot. This heat causes a distortion of the metal disc which opens the contacts and breaks the circuit. A circuit breaker that is open can be reset after it cools. Push the reset button to close the contacts and reset the circuit breaker.

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NOTICE

Find and correct the problem that causes the circuit breaker to open. This will help prevent damage to the circuit components from too much current.

Circuit Breaker Schematic
(1) Reset button (2) Disc in open position (3) Contacts (4) Disc (5) Battery circuit terminals

Oil Pressure Switch (OPS)

Oil Pressure Switch

The oil pressure switch uses a spring loaded piston to activate a micro switch for a specific pressure rating. This type of switch has better accuracy over the operating temperature range and uses a much higher electrical contact rating to improve reliability.

Slave Relay (SR)

This is a standard type relay that, when energized, has contacts that open across one circuit and close across another circuit. The circuits are wired so that voltage from the magneto goes to the spark plugs when the relay is energized. When not energized, the relay causes magneto voltage to go to ground. This relay is not used on the self-powered protection system.

Electronic Speed Switch (ESS)

Electronic Speed Switch (ESS)
(1) Verify button (2) Reset button (3) "LED" overspeed light (4) Seal screw plug (overspeed) (5) Seal screw plug (crank terminate)

The Electronic Speed Switch (ESS) is designed with controls built into a single unit to monitor several functions at the same time. The functions that the ESS monitors are:

Engine Overspeed (OS)

This is an adjustable engine speed setting (normally 118% of rated speed) that prevents the engine from running at a speed that could cause damage. This condition will cause a switch to close that shuts off the fuel to the engine and connects the magneto to ground to stop current flow to the spark plugs.

Crank Termination (CT)

This is an adjustable engine speed setting that signals the starter motor that the engine is firing and cranking must be terminated. When the speed setting is reached, a switch will open to stop current flow to the starter motor circuit. The starter motor pinion gear will now disengage from the engine flywheel ring gear.

Junction Box

Junction Box (Box for Self Powered Engine Shown)
(1) Terminal strips (TS) (2) Location for electric speed switch (ESS) (3) Emergency stop switch (ES) (4) Location for slave relay (SR) (5) Stop-by pass switch (SBS) [(also location for start-stop switch (SSS)] (6) Location for circuit breakers (CB)

The junction box contains the terminal strips (TS) and emergency stop switch (ES). An oil pressure switch (OPS) is located at the back of the junction box. Depending on the protection system used, the J box may also contain the electric speed switch (ESS), slave relay (SR), circuit breakers (CB), and start-bypass switch (SBS) or start-stop switch (SSS).

NOTE: The start-bypass switch is always located on the J box cover. A start-bypass switch may also be located on the bracket below the instrument panel on the right side of the engine to accommodate RH mounted starting controls.

Self-Powered Protection System

This system requires no external power for electrical protection. When started (by a separate system), the engine is protected from low oil pressure fault (OP) and high water temperature fault (WT). Overspeed protection (OS) is provided if a mechanical overspeed contactor switch is wired into the system. An optional energized-to-shutoff gas valve (GSOV) is available for this system.

The junction box for this system contains a start-bypass switch (SBS), emergency stop switch (ES), and an oil pressure switch (OPS1).

To follow the circuit operations of this protection system, refer to Electrical Schematic For Self-Powered Protection at the end of this text.

The point-to-point wiring diagrams for this protection system and junction box are located in the Wiring Diagrams section of this module.

Circuit Operation: No Faults

Engine Stopped

With the engine stopped, no electrical power is available to the system. The water temperature switch (WTS) and mechanical overspeed switch (MOS) are in their normally open positions. Oil pressure switch OPS1 is in its normally closed position.

Engine Startup

When the engine is started (by a separate system), the start-bypass switch must be held in the bypass (up) position (open between contacts SBS-2 & 3 and between SBS-5 & 6) until engine oil pressure is obtained. Magneto voltage is not allowed to travel to ground.

If the start-bypass switch is not held in the bypass position before oil pressure is achieved, magneto voltage will be allowed to travel through closed contacts SBS-2 & 3, through the closed oil pressure switch OPS1 and then to ground. The voltage traveling through the gas shutoff valve (if so equipped) energizes the valve coil, shutting off the gas to the engine. At the same time, the circuit between contacts GSOV-1 & 3 opens and the circuit between contacts GSOV-1 & 5 closes. This also grounds the magneto voltage, preventing spark to the cylinders.

Once oil pressure is achieved, oil pressure switch OPS1 will open and the start-bypass switch can be allowed to return to run (center) position (closed contacts between SBS-2 & 3, open contacts between SBS-4 & 5). Magneto voltage is not allowed to travel to ground.

Engine Running

When the engine is running with no problems, magneto voltage is not grounded. The oil pressure switch (OPS1), water temperature switch (WTS), mechanical overspeed switch (MOS), and emergency stop switch (ES) are all open. No magneto voltage is felt by the valve coil of the gas shut-off valve (GSOV), therefore gas is allowed to the engine.

Engine Normal Stop

The operator stops the engine by pressing the start-bypass switch to the stop (down) position to close contacts SBS-5 & 6. This allows the magneto voltage to go to ground, preventing spark at the cylinders. The valve coil of the gas shut-off valve (if so equipped), energized by the magneto voltage, then shuts off the gas supply. At the same time, the circuit between contacts GSOV-1 & 3 opens and the circuit between contacts GSOV-1 & 5 closes, grounding the magneto voltage.

Emergency Stop Switch (ES)

The emergency stop switch is the red button mounted on the junction box door. This switch will shut the engine down and prevent restarting until it is unlocked from the OFF position.

In the OFF position, magneto voltage is routed through closed contacts ES-3 & 4 and then to ground, preventing spark at the cylinders. The valve coil of the gas shut-off valve (if so equipped), energized by the magneto voltage, then shuts off the gas supply. At the same time, the circuit between contacts GSOV-1 & 3 opens and the circuit between contacts GSOV-1 & 5 closes to ground the magneto voltage.

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To prevent personal injury due to accidental starting of the engine, disconnect the batteries during maintenance or repair work.

Before starting the engine again, do the steps that follow:

1. Correct any faults that may have been the cause of the emergency shutdown.

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Unburned gas left in the manifold can ignite when the engine is restarted.

2. Before restarting any gas engine which was stopped by grounding the magneto, crank the engine with the gas valve turned off, and the magneto grounded, for 10 to 15 seconds. This will clear the unburned gas from the exhaust system.

3. Make sure the ES has been reset (pushbutton is out) on the engine junction box. To reset, turn the pushbutton in the direction shown on the button face.

4. Manually reset the gas shut-off valve (if so equipped).

5. Start the engine again while holding the start-bypass switch (SBS) in the up (bypass) position until oil pressure is achieved.

Fault Circuit Operation

Low Oil Pressure (OP), Coolant Overheating (WT), Engine Overspeed (OS) - Optional

When the engine is running, any one of the following faults will cause magneto voltage to be grounded through the respective switch:

1. Oil pressure drops below setting of oil pressure switch OPS1 and causes it to close.

2. Coolant temperature exceeds setting of water temperature switch (WTS) and causes it to close.

3 Engine increases above the overspeed setting of the mechanical overspeed switch (MOS) (if provided) and causes it to close.

When the magneto is grounded, spark is no longer available to the cylinders. Magneto voltage going to any of the closed switches also energizes the gas shut-off valve (if so equipped). The energized GSOV then shuts off the gas supply. At the same time, the circuit between contacts GSOV-1 & 3 opens and the circuit between contacts GSOV-1 & 5 closes, grounding the magneto voltage.

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Unburned gas left in the manifold can ignite when the engine is restarted.

Before restarting any gas engine which was stopped by grounding the magneto, crank the engine with the gas valve turned off, and the magneto grounded, for 10 to 15 seconds. This will clear the unburned gas from the exhaust system.

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NOTICE

To avoid engine damage, repair or correct the problem that causes engine shutdown before restarting.

NOTE: Additional engine fault protection modes may be provided by the owner by adding the appropriate normally open or normally closed switches between terminal strip points TS-1, 2, or 3 and TS-28.

Electrical Schematic (JIC Symbols) Self-Powered Protection

Refer to these notes and abbreviations when using Electrical Schematic for Self-Powered Protection.

NOTES

NOTE F: Attach ground wire to ground strap bolt on junction box mounting bracket.

NOTE G: Jumper on junction box terminal strip between points TS-30 and TS-31 must be removed when right-hand mounted start-stop switch is used on engine.

NOTE H: When starting engine, stop-bypass switch must be held in up position until oil pressure is achieved. Failure to do so will result in engine shutdown.

NOTE N: Magneto shutoff contacts:

Altronic ... G

Fairbanks-Morse ... H

NOTE P: Remove jumper between terminal points TS-31 and TS-32 when gas shutoff valve is used.

Electrical Schematic (JIC Symbols) Self-Powered Protection

ETR, Independent, Full Protection System

This fully independent system requires external 24 VDC power for electrical engine protection. The engine is monitored for engine overspeed (OS) oil pressure (OP) and water temperature (WT). The gas shutoff valve (GSOV) is energized to run (ETR).

The junction box contains an electric speed switch (ESS), slave relay (SR1), oil pressure switch (OPS1), circuit breaker (CB5), start-stop switch (SSS) and emergency stop switch (ES). With this system, the slave relay remains energized in order for the engine to run.

To follow the circuit operations of this protection system, refer to the Electrical Schematic For ETR, Independent, Full Protection at the end of this text.

The point-to-point wiring diagrams for this protection system and junction box are located in the Wiring Diagrams section of this module.

Circuit Operation: No Faults

Engine Stopped

With the engine stopped, power is always available across terminals 5 and 6 (line 54) of electronic speed switch (ESS). At this time all switches are in their normally open or normally closed positions.

Engine Start-Up

NOTE: On the front of the junction box door there is a start-stop toggle switch that is spring loaded. It will automatically return to the center (RUN) position when released from the START position.

When the Start-Stop Switch (SSS) is moved to the START position (up), the circuit to the starter motor is closed across terminals SSS-2 and SSS-1 (line 9). The starter motor magnetic switch (SMMS) (line 9) now energizes to close its contact (line 3) to energize the pinion solenoid (PS) (line 3). Solenoid PS then closes its contact (line 2) to energize the starter motor (SM).

At the same time, current flows across terminals SSS-11 and SSS-10 (line 24), arming slave relay SR1 (line 36) and the energized-to-run gas shutoff valve GSOV (line 39). The energized SR1 opens its contacts across terminals SR1-1 and SR1-2 (lines 45 and 47) and closes its contacts across terminals SR1-1 and SR1-3 (lines 45 and 43) preventing the magneto (MAG) from being grounding.

When the engine starts to run and the crank termination speed setting is reached, electronic speed switch (ESS) crank terminate switch (CT) opens its contacts across terminals ESS-11 and ESS-12 (line 17) and closes its contacts across terminals ESS-10 and ESS-11 (line 17).

When ESS(CT) contacts open across terminals ESS-11 and ESS-12, current flow is stopped to the starter motor circuit and the starter motor (SM) will now stop.

At this point, the engine has started to run. Crank termination setting is reached, but oil pressure is not yet achieved. The SSS is still held in the START position. Current is flowing through ESS (CT) terminals ESS-11 and ESS-10, ESS(OS) terminals ESS-8 and ESS-9 (line 20), ES terminals ES-1 and ES-2 (line 18), WTS terminals WTS-2 and WTS-3 (lines 18 and 19), and SSS terminals SSS-11 and SSS-10 (line 24). Oil pressure switch OPS1, open at terminals OPS1-1 and OPS1-2 (line 13) due to low oil pressure, is bypassed.

When oil pressure is achieved, oil pressure switch contact terminals OPS1-1 and OPS1-3 will open and terminals OPS1-1 and OPS1-2 will close. The SSS switch can be released to its normal RUN position, to close contacts across terminals SSS-11 & 12 (line 24). OPS1 is now included in the circuit, and full protection (OP, WT, OS) is in effect.

Engine Running

With no engine problems and engine running, oil pressure switch (OPS1) (line 13) is closed across contacts OPS1-1 and OPS1-2, so there is still current flow to energize slave relay SR1 (line 36) and gas shutoff valve GSOV (line 39). The engine will continue to run with these conditions.

Engine Normal Stop

The operator stops the engine by pressing the start-stop switch (SSS) from the RUN position (horizontal) to the STOP position (down).

When moved to STOP position, SSS opens across contacts SSS-5 and SSS-4 (line 24) to stop current flow through OPS1 (line 13) terminals OPS1-1 and OPS1-2. With no current from OPS1, gas shutoff valve GSOV (line 39) closes and SR1 (line 36) is de-energized. SR1 contact terminals SR1-1 and SR1-3 open and terminals SR1-1 and SR1-2 close, grounding the magneto (MAG) and preventing spark from reaching the cylinders.

After complete engine shutdown is accomplished, the electronic speed switch ESS(CT) closes across terminals ESS-11 and ESS-12 (line 17) to allow for restart. The engine can now be immediately restarted.

Emergency Stop Switch (ES)

The emergency stop switch (ES) is a red, mushroom shaped pushbutton that is located on the front of the junction box door. This pushbutton will shut the engine down and will also prevent the engine from being restarted, because it locks in the OFF (in) position.

When pushed in, ES creates an open circuit across contacts ES-1 and ES-2 (line 18). Flow of current is stopped to SR1 (line 36) and GSOV (line 39). The energized-to-run gas valve closes. At the same time, relay SR1 closes its contact between SR1-1 and SR1-2 (line 47) to connect the magneto (MAG) to ground and stop current flow to the spark plugs.

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To prevent personal injury due to accidental starting of the engine, disconnect the batteries during maintenance or repair work.

Before starting the engine again, do the steps that follow:

1. Correct any faults that may have been the cause of the emergency shutdown.

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Unburned gas left in the manifold can ignite when the engine is restarted.

3. Make sure the ES has been reset (pushbutton is out) on the engine junction box. To reset, turn the pushbutton in the direction shown on the button face.

4. Start the engine again with the Start-Stop Switch (SSS).

Fault Circuit Operation

Low Oil Pressure (OP), Coolant Overheating (WT), Engine Overspeed (OS)

When the engine is running with no problems, electric current for gas shutoff valve (GSOV) and slave relay (SR1) travels through ESS overspeed ESS(OS), water temperature switch (WTS), and oil pressure switch (OPS1). Any one of the following faults will stop current flow to GSOV and SR1. When de-energized, GSOV will close to shut off gas and SR1 will cause the magneto (MAG) to be grounded to prevent spark to the cylinders.

1. Oil pressure drops below rating of OPS1, causing contacts between terminals OPS1-1 and OPS1-2 (line 13) to open.

2. Coolant temperature exceeds setting of WTS, causing contacts WTS-2 and WTS-3 (line 18) to open.

3. Engine speed increases above the overspeed setting of ESS(OS), opening contacts ESS-8 and ESS-9 (line 29).

NOTE: A reset button on the ESS must be pushed to open the overspeed switch ESS(OS) before the engine can be restarted.

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Unburned gas left in the manifold can ignite when the engine is restarted.

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NOTICE

To avoid engine damage, repair or correct the problem that causes engine shutdown before restarting.

2301 Electric Governor Control System

When the 2301 Electric Governor Control (EGC) is used, all components of the protection system are activated in the same way as discussed with the nonelectric governors.

Electrical Shematic (JIC Symbols) ETR, Independent, Full Protection

Refer to these notes and abbreviations when using Electrical Schematic for ETR, Independent, Full Protection.

NOTES

NOTE D: If electric starting motor not used connect battery cables to power input studs on bottom of power distribution box. If neither electric starting motor nor charging alternator is used, connect positive lead of 24 VDC power source to TS1 on junction box terminal strip and negative to TS28.

NOTE M: Jumper on terminal strip between points TS-4 & 5 must be removed when a remote normal stop switch is used.

NOTE N: Magneto shutoff contacts:

Altronic ... G

Fairbanks-Morse ... H

Electrical Shematic (JIC Symbols) ETR, Independent, Full Protection

ETR, Auto Start-Stop, Full Protection System

This system (full system without switchgear) is not an independent system. It is designed for the customer who already has his own switchgear. After the customer switchgear is wired into this junction box, it becomes functional and will monitor engine overspeed, oil pressure, coolant temperature and starter motor overspeed. The gas shutoff valve is energized to run.

This junction box contains an electronic speed switch (ESS), slave relay (SR1), oil pressure switch (OPS1), circuit breaker (CB5), and emergency stop switch (ES). With this system, the slave relay remains energized in order for the engine to run.

To follow the circuit operations, refer to the Electrical Schematic For ETR, Auto-Start-Stop, Full Protection at the end of this text.

The point-to-point wiring diagrams for this protection system and junction box can be found in the Wiring Diagram section of this module.

Electrical Schematic (JIC Symbols) ETR, Auto-Start-Stop, Full Protection

Refer to these notes and abbreviations when using Electrical Schematic For ETR Auto Start-Stop, Full Protection.

NOTES

NOTE D: If electric starting motor is not used, connect battery cables to power input studs on bottom of power distribution box. If neither electric starting motor nor charging alternator is used, connect positive lead of 24 VDC power source to TS-1 on junction box terminal strip and negative to TS-28.

NOTE N: Magneto shutoff contacts:

Altronic ... G

Fairbanks-Morse ... H

Electrical Schematic (JIC Symbols) ETR, Auto-Start-Stop, Full Protection

Circuit Operation

The circuit operation of this system will function the same as the ETR, Independent, Full Protection except for the operation of the start-stop switch (SSS). To interface with customer supplied switchgear, use the suggestions (for a three position triple-pole, double-throw type start-stop switch) that follow:

1. Connect switch so that two normally-open START position contacts are across J box terminal strip terminals TS-21 and TS-26 and across TS-4 and TS-14.

2. Connect switch so that RUN position contacts are across J box terminal strip terminals TS-4 and TS-5. Ensure that this RUN position contact opens when switch is placed in STOP position and is closed when the switch is placed in the RUN position.

NOTE: To avoid premature engine shutdown, switch must be held in the START position until oil pressure is seen on the oil pressure gauge.

Connections For Temporary Start-up

If an engine with this system needs to be started temporarily before installation in plant, use the wiring suggestions that follow:

1. Connect a START switch across J box terminal strip with one normally-open contact between terminals TS-21 & TS-26 and one normally-open contact between terminals TS-4 & TS-14. These contacts must act simultaneously when START switch is activated.

2. Connect RUN-STOP switch so that a contact is connected between J box terminals TS-4 and TS-5. This contact must be closed in the RUN position and open in the STOP position.

All fault circuits are now operational as they would be if the engine was in its final installation. The only difference is that the engine must have enough oil pressure to open OPS1 at the time the engine just starts to run. If not, this circuit will cause immediate shutdown of the engine.

Wiring Diagrams

Engine Protection Systems; Starting, Charging, and Tachometer Circuits

This section contains point-to-point wiring diagrams for the engine protection systems and starting, charging, and tachometer circuits.

These diagrams can be helpful for the user who is not familiar with the electrical schematic-type format, or who is interested in the component position layout for replacement purposes.

Refer to the notes and abbreviations on this page when using the wiring diagrams in this section. See the chart on the following page for the battery cable size.

NOTES

NOTE A: Cable to be grounded at tachometer only when used without electric speed switch. Ground cable at speed switch when available.

NOTE B: Grounded system required for proper operation of shut-off system.

NOTE C: If 2301 Governor is used, only one magnetic pick-up is required. Use magnetic pick-up from speed switch. Connect mag pick-up to speed switch and then to 2301 Governor Control. Do not use multiple grounds on any particular length of shielded cable.

NOTE E: Diagrams and schematics for junction box wiring shipped inside junction box.

NOTE F: Attach ground wire to ground strap bolt on junction box mounting bracket.

NOTE G: Jumper on junction box terminal strip between points TS-30 and TS-31 must be removed when right-hand mounted start-stop switch is used on engine. (No external power source).

NOTE H: When starting engine, stop-bypass switch must be held in up position until oil pressure is achieved. Failure to do so will result in engine shutdown.

NOTE J: Attach ground wire to start-stop switch mounting bracket bolt.

NOTE K: Required only with Fairbanks-Morse magneto with variable timing.

NOTE L: Start-stop switch required with oil pressure, water temp, overspeed protection system only when used in a non-auto-start-stop application.

NOTE M: Jumper on terminal strip between points TS-4 and TS-5 must be removed when a remote normal stop switch is used.

NOTE N: Magneto shutoff contacts:

Altronic ... G

Fairbanks-Morse ... H

NOTE P: Remove jumper between terminal points TS-31 and TS-32 when gas shutoff valve is used.

Wiring Diagram Starting, Charging, Tachometer Circuits (Engine With Self-Powered Protection)

Wiring Diagram Self-Powered Protection

Wiring Diagram - ETR, Independent, Full Protection Wiring Diagram - ETR, Auto-Start-Stop, Full Protection

Junction Box Wiring Diagrams

This section contains point-to-point wiring diagrams for the junction boxes used with the engine protection systems. These diagrams can be helpful for the user who is not familiar with the electrical schematic-type format, or who is interested in the component position layout for replacement purposes.

NOTE: The junction boxes for the ETR independent and ETR auto-start-stop protection systems are used for other engines in addition to the spark-ignited 3408 and 3412. Therefore, some components shown in the junction box wiring diagrams for the ETR protection systems will not apply to the spark-ignited 3408 and 3412.

Refer to the abbreviations on this page when using the wiring diagrams in this section.

Junction Box Wiring Diagram Self-Powered Protection

Junction Box Wiring Diagram ETR, Independent, Full Protection

Junction Box Wiring Diagram ETR, Auto-Start-Stop, Full Protection

Troubleshooting

Troubleshooting can be difficult. On the following pages there is a list of possible problems. To make a repair to a problem, make reference to the cause and correction.

This list of problems, causes and corrections will only give an indication of where a possible problem can be, and what repairs are needed. Normally, more or other repair work is needed beyond the recommendations in the list. Remember that a problem is not normally caused only by one part, but by the relation of one part with other parts. This list can not give all possible problems and corrections. The serviceman must find the problem and its source, then make the necessary repairs.

NOTE: Problems 1 through 5 are for troubleshooting the self-powered engine protection system. To troubleshoot the energized-to-run (ETR) protection systems, refer to Troubleshooting Guide (ETR), Form No. SENR3609.

Problem Index

1. Contactor Switch (Water Temperature) Fails to Signal Shutoff.

2. Contactor Switch (Water Temperature) Signals Shutoff at Low Temperature.

3. Oil Pressure Contactor Fails to Signal Shutoff.

4. Overspeed Contactor Switch Fails to Signal Shutoff.

5. Overspeed Contactor Switch Signals Shutoff at Low Speed.

6. Clutch Will Not Engage (Slips), Heats or Lever Moves to Released Position.

7. Clutch Shaft Has Too Much End Play.

8. Clutch Bearings Have Short Service Life.

Problem Checklist

Problem 1. Contactor Switch (Water Temperature) Fails To Signal Shutoff

Probable Cause

1. Incorrect Electrical Connections

Check connections to other components or install new wiring. See WIRING DIAGRAM for SELF-POWERED PROTECTION in the WIRING DIAGRAMS section.

2. Low Water Level in Cooling System

Fill the cooling system.

3. Incorrect Setting

Test operation (trip) temperature setting and if necessary install new contactor switch with proper setting. See Specifications.

Problem 2. Contactor Switch (Water Temperature) Signals Shutoff At Low Temperature

Probable Cause

1. Incorrect Setting

Test operating (trip) temperature setting and if necessary install new contactor switch with proper setting. See Specifications.

Problem 3. Oil Pressure Contactor Fails To Signal Shutoff

Probable Cause

1. Incorrect Electrical Connections

See JUNCTION BOX WIRING DIAGRAM for SELF-POWERED PROTECTION in the WIRING DIAGRAMS section for the correct wiring connections.

2. Incorrect Setting

Test and adjust contactor. If necessary install new contactor switch.

Problem 4. Overspeed Contactor Switch Fails To Signal Shutoff

Probable Cause

1. Incorrect Electrical Connections

Check connection, wiring and correct where necessary. See WIRING DIAGRAM for SELF-POWERED PROTECTION in the WIRING DIAGRAMS section.

2. Incorrect Setting

Adjust setting or install new contactor switch with the correct rpm range if necessary.

Problem 5. Overspeed Contactor Signals Shutoff At Low Speed

Probable Cause

1. Incorrect Setting

Adjust setting or install new contactor switch with the correct rpm range if necessary.

Problem 6. Clutch Will Not Engage (Slips), Heats Or Lever Moves To Released Position

Probable Cause

1. Wrong Adjustment

Make adjustment to clutch engagement lever pull.

2. Alignment of Flywheel and Flywheel Housing Mounting Face and Bores

Check and make adjustment to alignment.

3. Overload on Clutch

Reduce load or reduce engine speed when engaging clutch.

Problem 7. Clutch Shaft Has Too Much End Play

Probable Cause

1. Bearing Worn or Adjustment Wrong

Replace and/or make adjustment to shaft bearing.

Problem 8. Clutch Bearings Have Short Service Life

Probable Cause

1. Too Much Bearing Clearance

Replace and/or make adjustment to shaft bearing.

2. Side Load Too High

Make a reduction of side load.

Power Take-Off Clutches

Clutch Adjustment

1. Disconnect linkage (if so equipped) from the clutch lever.

2. Use a torque wrench and apply torque to the splined clutch lever shaft until the clutch engages. The correct amount of torque needed to engage the clutch is 295 to 392 N·m (214 to 291 lb.ft.).

3. If the torque needed to engage the clutch is not correct, make an adjustment as follows:

4. Remove the inspection plate from the clutch housing.

5. Turn the clutch until lock pin (1 or 2) can be seen.

6. Release push type lock pin (1) or pull type lock pin (2). Turn the adjustment ring and check the torque needed to engage the clutch again.

NOTE: Turn the adjustment ring clockwise, as seen from the rear of the clutch, to increase the torque needed. Turn it counterclockwise to decrease the torque needed.

Clutch Adjustment
(1) Lock pin (push type) (2) Lock pin (pull type)

Assembly Adjustments

End Play For Shaft Bearings

1. With dry bearings installed on the shaft install the shaft in the housing.

2. Install the retainer. Tighten the retainer until there is no clearance between the bearing cups and cones.

3. Loosen the retainer 2 to 3 notches.

4. Hit the output end of the clutch shaft. This will cause the front bearing cup to move against the retainer.

5. Check the shaft end play with a dial indicator. If necessary, turn nut to get the correct end play. Correct shaft end play is 0.15 to 0.25 mm (.006 to .010 in.).

Flywheel And Flywheel Housing Alignment

At the time of installation of rear mounted PTO's, check the flywheel and flywheel housing face and bore run out.

Instruments And Gauges

Oil Pressure Sending Units

Sending Unit for Oil Pressure (Typical Example)
(1) Terminal (2) Fitting

1. Connect the sending unit to a pressure source that can be measured with accuracy.

2. Connect an ohmmeter between fitting (2) and terminal (1).

3. Take resistance readings at the pressure shown in the Specifications.

4. If a unit does not have the correct resistance readings, make a replacement of the unit.

Water Temperature Sending Unit

1. Connect an ohmmeter between terminal (1) and nut (2). Put bulb (3) in a pan of water. Do not let the bulb have contact with the pan.

2. Put a thermometer in the water to measure the temperature.

Sending Unit for Water Temperature
(1) Terminal (2) Nut (3) Bulb

3. Take resistance readings at the temperatures shown in the Specifications.

4. If a unit does not have the correct resistance readings, make a replacement of the unit.

Mechanical Gauges For Temperature

To check these gauges, put the bulb of the gauge in a pan of oil. Do not let the bulb touch the pan. Put a thermometer in the oil to measure the temperature. Make a comparison of temperatures on the thermometer with the temperatures on the direct reading gauge.

Mechanical Gauges For Oil Pressure

To check these gauges connect the gauge to a pressure source that can be measured with accuracy. Make a comparison of pressure on the gauge of test equipment with the pressure on the direct reading gauge.

Contactor Switch For Water Temperature

Fabricated heat sink.2F7112 Thermometer.3J5389 Plug.8T500 Circuit Tester.

1. Make a heat sink as shown. Material can be brass, steel or cast iron. Drill a 17.8 mm (.70 in.) hole through the plate and use a tap to make 1/2 in. NPT threads.

2. Put marks on the two contactor wires that connect the contactor to the circuit. Disconnect the two wires.

Heat Sink [Dimensions in mm (in.)]

3. Remove the contactor and install a 3J5389 Plug. Install the contactor switch in the heat sink.

4. Put the heat sink and contactor in water as shown. Use blocks to support the heat sink at surface level.

5. Connect the 8T500 Circuit Tester between the wires that connected the contactor to the circuit.

Test of Contactor Switch
(1) 2F7112 Thermometer (2) Fabricated heat sink

6. Put the 2F7112 Thermometer in the water.

7. Use a torch to heat the water to the temperature range at which the contactor must activate. If the circuit test light does not come on within the temperature range given in the Specifications make a replacement of the contactor.

8. Let the water temperature go down. If the circuit tester light does not go out within the temperature range given in the Specifications make a replacement of the contactor.

Overspeed Contactor Switch (Mechanical)

6B344 Tach Drive Adapter5L8184 Tach Drive Adapter (3408 only)6V7800 Multimeter

1. Install 6B344 Tach Drive Adapter between the tach drive and the overspeed contactor. On 3408 engines, the 5L8184 Tach Drive Adapter must also be installed between the 6B344 Tach Drive Adapter and the overspeed contactor. The 6B344 Tach Drive Adapter provides a 1 to 2 increase drive ratio. The 5L8184 Tach Drive Adapter has a 1 to 1 drive ratio and is used only to provide clearance for the overspeed contactor on the 3408 engine.

2. Determine the overspeed setting using the chart shown. For rated speed not shown in chart, use 118% of rated speed ± 25 rpm.

3. Identify (for reassembly) and disconnect harness wires from C (common) and NO (normally open) terminals of the overspeed contactor. Insulate each disconnected wire with tape.

4. Reset the overspeed contactor by pressing the button on top of the overspeed contactor case.

5. Connect the 6V7800 Multimeter to the C and NO terminals of the overspeed contactor. Check for continuity. If there is continuity, replace the overspeed contactor.

6. Remove the tag wire and loosen three lockscrews (1). Adjust the contactor all the way out by turning the contactor base CCW until the end of the screw slots are against the lockscrews.

7. Start the engine and, using an engine tachometer accurate to ±1%, run the engine to 1/2 of the overspeed setting rpm.

8. Adjust the overspeed contactor setting by gradually turning the contactor case CW until the overspeed contactor relay trips as indicated by a continuity reading on the 6V7800 Multimeter between the C and NO terminals. If the overspeed contactor is turned all the way CW and the multimeter shows no continuity, replace the overspeed contactor.

9. Tighten three lockscrews (1).

10. Shut off the engine. Remove the 6V7800 Multimeter from the overspeed contactor. Reconnect the harness wires to the C and NO terminals of the overspeed contactor.

11. Reset the overspeed contactor by pressing the button on top of the overspeed contactor case.

12. Restart the engine and observe the overspeed set point rpm by rapidly increasing engine rpm until engine rated speed is reached or until the overspeed contactor relay trips as indicated by automatic engine shutdown. If the engine automatically shuts down before the engine rated speed is reached, then proceed to the next step. If the engine does not automatically shut down before engine rated speed is reached, and wiring and connections are correct, then replace the overspeed contactor.

13. If the observed overspeed set point rpm is within ±12% of 1/2 of the overspeed setting, then the overspeed contactor is properly adjusted. If the overspeed set point rpm is not within ± 12 rpm of 1/2 of the overspeed setting, then repeat the procedure starting with Step 3.

14. Shut off the engine. Remove the 6B344 Tach Drive Adapter and, if used, the 5L8184 Tach Drive Adapter from between the tach drive and overspeed contactor. Reinstall the overspeed contactor.

15. Install lockwire to three lockscrews (1).