Introduction

The specifications given in this book are on the basis of information available at the time the book was written. These specifications give the torques, operating pressure, measurements of new parts, adjustments and other items that will affect the service of the product.

When the words "use again" are in the description, the specification given can be used to determine if a part can be used again. If the part is equal to or within the specification given, use the part again.

When the word "permissible" is in the description, the specification given is the "maximum or minimum" tolerance permitted before adjustment, repair and/or new parts are needed.

A comparison can be made between the measurements of a worn part, and the specifications of a new part to find the amount of wear. A part that is worn can be safe to use if an estimate of the remainder of its service life is good. If a short service life is expected, replace the part.

NOTE: The specifications given for "use again" and "permissible" are intended for guidance only and Caterpillar Tractor Co. hereby expressly denies and excludes any representation, warranty or implied warranty of the reuse of any component.

NOTE: This engine uses bolts (3/8 inch size only) with washer heads in some locations. The washer head bolt does not need a plain washer, lockwasher or lockplate. Where these bolts are used on aluminum covers or housings, a plain washer is needed. If you are not sure a washer is used under a bolt head, use the Parts Book to see if a washer is needed.

Glossary

arcing:

a discharge of electricity across a gap

acceleration:

rate at which speed increases

bus:

an electrical conductor

compare:

look at for differences

cranking:

rotation of the engine by the starter motor

circuit:

connected electric components

deactivate:

stop a function

deceleration:

rate at which speed decreases

de-energized:

power off

energized:

power on

failsafe:

circuit that gives protection

hertz:

cycles per second

hunt:

speed changes

hydra-mechanical:

hydraulically controlled mechanical action

inversely:

the opposite of directly

isochronous:

desired engine speed does not change because of a change in load

jumper:

electrical connection

kilowatt:

measure of electric power

overspeed:

engine speed higher than rated speed

override:

cause normal electrical signals to be canceled

nonparallel:

single

paralleled:

electrically connected together to drive a common load

paralleling:

all positive poles are connected to one conducter and all negative poles are connected to another conductor

proportion:

a ratio

proportional:

two factors that have a constant ratio

potentiometer:

electric component that has variable resistance

ramp:

circuit that controls movement from one level to another

response:

time and stability characteristic of a change in output

sensing phasing:

measurement and comparison of output with other units in the system

short:

any connection between two or more electrical components that is not desired

shielding:

steel braid for protection of a wire

sharing:

two or more engines used to drive a common load

speed droop:

no load engine rpm minus full load rpm

standby:

ready for use during an emergency

transfer:

change from one to another

Woodward PSG Governors

SCHEMATIC OF LATEST PSG GOVERNOR
1. Return spring. 2. Output shaft. 3. Output shaft lever. 4. Strut assembly. 5. Speeder spring. 6. Power piston. 7. Flyweights. 8. Needle valve. 9. Thrust bearing. 10. Pilot valve compensating land. 11. Buffer piston. 12. Pilot valve. 13. Pilot valve bushing. 14. Control ports. A. Chamber. B. Chamber.

Introduction

The Woodward PSG (Pressure compensated Simple Governor) can operate as an isochronous or a speed droop type governor. It uses engine lubrication oil, increased to a pressure of 175 psi (1200 kPa) by a gear type pump inside the governor, to give hydra/mechanical speed control.

Pilot Valve Operation

The fuel injection pump camshaft drives a governor drive unit. This unit turns pilot valve bushing (13) clockwise as seen from the drive unit end of the governor. The pilot valve bushing is connected to a spring driven ballhead. Flyweights (7) are fastened to the ballhead by pivot pins. The centrifugal force caused by the rotation of the pilot valve bushing causes the flyweights to pivot out. This action of the flyweights changes the centrifugal force to axial force against speeder spring (5). There is a thrust bearing (9) between the toes of the flyweights and the seat for the speeder spring. Pilot valve (12) is fastened to the seat for the speeder spring. Movement of the pilot valve is controlled by the action of the flyweights against the force of the speeder spring.

The engine is at the governed (desired) rpm when the axial force of the flyweights is the same as the force of compression in the speeder spring. The flyweights will be in the position shown. Control ports (14) will be closed by the pilot valve.

Fuel Increase

When the force of compression in the speeder spring increases (operator increases desired rpm) or the axial force of the flyweights decreases (load on the engine increases) the pilot valve will move in the direction of the drive unit. This opens control ports (14). Pressure oil flows through a passage in the base to chamber (B). The increased pressure in chamber (B) causes power piston (6) to move. The power piston pushes strut assembly (4), that is connected to output shaft lever (3). The action of the output shaft lever causes counterclockwise rotation of output shaft (2). This moves fuel control linkage (15) in the FUEL ON direction.

PSG GOVERNOR INSTALLED
2. Output shaft. 15. Fuel control linkage.

As the power piston moves in the direction of return spring (1) the volume of chamber (A) increases. The pressure in chamber (A) decreases. This pulls the oil from the chamber inside the power piston, above buffer piston (11) into chamber (A). As the oil moves out from above buffer piston (11) to fill chamber (A) the buffer piston moves up in the bore of the power piston. Chambers (A and B) are connected respectively to the chambers above and below the pilot valve compensating land (10). The pressure difference felt by the pilot valve compensating land adds to the axial force of the flyweights to move the pilot valve up and close the control ports. When the flow of pressure oil to chamber (B) stops so does the movement of the fuel control linkage.

Fuel Decrease

When the force of compression in the speeder spring decreases (operator decreases desired rpm) or the axial force of the flyweights increases (load on the engine decreases) the pilot valve will move in the direction of speeder spring (5). This opens control ports (14). Oil from chamber (B) and pressure oil from the pump will dump through the end of the pilot valve bushing. The decreased pressure in chamber (B) will let the power piston move in the direction of the drive unit. Return spring (1) pushes against strut assembly (4). This moves output shaft lever (3). The action of the output shaft lever causes clockwise rotation of output shaft (2). This moves fuel control linkage (15) in the FUEL OFF direction.

EARLIER PSG GOVERNOR
6. Power piston. 8. Needle valve. 10. Pilot valve compensating land. 11. Buffer piston. 14. Control ports. A. Chamber. B. Chamber.

As power piston (6) moves in the direction of the drive unit the volume of chamber (A) decreases. This pushes the oil in chamber (A) into the chamber above buffer piston (11). As the oil from chamber (A) flows into the power piston it moves the buffer piston down in the bore of the power piston. The pressure at chamber (A) is more than the pressure at chamber (B). Chambers (A and B) are connected respectively to chambers above and below the pilot valve compensating land (10). The pressure difference felt by the pilot valve compensating land adds to the force of the speeder spring to move the pilot valve down and close the control ports. When the flow of oil from chamber (B) stops so does the movement of the fuel control linkage.

Hunting

There is a moment between the time the fuel control linkage stops its movement and the time the engine actually stops its increases or decrease of rpm. During this moment there is a change in two forces on the pilot valve, the pressure difference at the pilot valve compensating land and the axial force of the flyweights.

The axial force of the flyweights changes until the engine stops its increase or decrease of rpm. The pressure difference at the pilot valve compensating land changes until the buffer piston returns to its original position. A needle valve (8) in a passage between space (A) and (B) controls the rate at which the pressure difference changes. The pressure difference makes compensation for the axial force of the flyweights until the engine stops it increase or decrease of rpm. If the force on the pilot valve compensating land plus the axial force of the flyweights is not equal to the force of the speeder spring the pilot valve will move. This movement is known as hunting (movement of the pilot valve that is not the result of a change in load or desired rpm of the engine).

The governor will hunt each time the engine actually stops its increase or decrease of rpm at any other rpm than that desired. The governor will hunt more after a rapid or large change of load or desired rpm than after a gradual or small change.

PSG GOVERNOR INSTALLED
8. Needle valve.

Speed Adjustment

The earliest PSG governors use a screw (1). When the screw is turned clockwise it pushes the link assembly (2) down. This causes an increase in the force of speeder spring (3) and pilot valve (4) will move down. See PILOT VALVE OPERATION. The engine will increase speed until it gets to the desired rpm. When the screw is turned counterclockwise the link assembly moves up. This causes a decrease in the force of the speeder spring and the pilot valve will move up. The engine will decrease speed until it gets to the desired rpm.

Later PSG governors use a clutch assembly (6) driven by a 110V AC/DC or 24V DC reversible synchronizing motor (5) to move link assembly (7) up or down. The clutch assembly protects the motor if the adjustment is run against the stops. The motor is controlled by a switch that is remotely mounted. The clutch assembly can be turned manually if necessary.

EARLIEST PSG GOVERNOR
1. Screw. 2. Link assembly. 3. Speeder spring. 4. Pilot valve.

LATER PSG GOVERNOR
5. Synchronizing motor. 6. Clutch assembly. 7. Link assembly.

Speed Droop

EARLIER PSG GOVERNOR
1. Bracket. 2. Pivot pin. 3. Output shafts.

Speed droop is the difference between no load rpm and full load rpm. This difference in rpm divided by the full load rpm and multiplied by 100 is the percent of speed droop.

The speed droop of the PSG governor can be adjusted. The governor is isochronous when it is adjusted so that the no load and full load rpm is the same. Speed droop permits load division between two or more engines that drive generators connected in parallel or generators connected to a single shaft.

Speed droop adjustment on PSG governors is made by movement of pivot pin (2). When the pivot pin is put in alignment with the output shafts, movement of the output shaft lever will not change the force of the speeder spring. When the force of the speeder spring is kept constant the desired rpm will be kept constant. See PILOT VALVE OPERATION. When the pivot pin is moved out of alignment with the output shafts, movement of the output shaft lever will change the force of the speeder spring proportional to the load on the engine. When the force of the speeder spring is changed the desired rpm of the engine will change.

On earlier PSG governors the cover must be removed to adjust the speed droop. Later models have an adjustment lever outside the governor connected to pivot pin (2) by link (4).

LATER PSG GOVERNOR
2. Pivot pin. 4. Link.

2301 Nonparallel Control System

NONPARALLEL CONTROL BOX

The 2301 Nonparallel Control gives exact engine speed control. The system measures engine speed constantly and makes necessary corrections to the engine fuel setting through an actuator connected to the fuel system.

The engine speed is felt by a magnetic pickup. As the teeth of the flywheel go through the magnetic lines of force around the pickup an AC voltage is made. The ratio between the frequency of this voltage and the speed of the engine is directly proportional. An electric circuit inside the control box feels the AC voltage. In response it sends a DC control voltage, inversely proportional to engine speed, to the actuator.

The actuator is connected to the fuel system by linkage. It changes the electrical input from the control box to mechanical output that changes the engine fuel setting. For example, if the engine speed was more than the speed setting, the control box will decrease its output and the actuator will decrease fuel to the engine.

The rated and low idle engine speeds are set with speed setting potentiometers. An optional remote speed trim potentiometer will give ± 6% speed setting adjustment. A capacitor can be used between terminals 15 and 16 to control the amount of time it takes the engine to go from low idle to rated speed. An oil pressure switch is connected between terminals 9 and 10. This switch is normally open. When the engine oil pressure increases to 6.4 ± 2.7 psi (44 ± 19 kPa) the switch closes. This permits the control to accelerate the engine to rated speed. If the oil pressure decreases to 3.9 ± 3.3 psi (27 ± 23 kPa) the control will return the engine to low idle.

ACTUATOR

MAGNETIC PICKUP

The gain and stability protentiometers control the response of the engine to a change in load. The gain potentiometer is used to decrease response time to a minimum. The stability potentiometer is used to get the best speed stability for the gain setting that is used.

A droop potentiometer can be connected between terminals 13, 14 and 15 to control the amount of speed droop. Droop is necessary when paralleling with a utility bus or a unit with a hydra/mechanical governor.

The speed failsafe circuit will return the voltage output of the control to zero if the magnetic pickup signal has a failure. This will cause the actuator to move to the FUEL OFF position. Also the engine will not start if the magnetic pickup signal has a failure.

NOTE: On the 7N182 Control Box the jumper between terminals 3 and 4 must be removed to deactivate the speed failsafe circuit for test purposes. On the 8N408 Control Box a jumper must be added between terminals 3 and 4 to deactivate the failsafe circuit for test purposes.

WIRING DIAGRAM FOR 2301 NONPARALLEL CONTROL BOX

For more information, make reference to Special Instruction Form No. SEHS7367.

2301 Parallel Control System

2301 PARALLEL CONTROL BOX

The 2301 Parallel Control has two functions: exact engine speed control and kilowatt load sharing. The system measures engine speed constantly and makes necessary corrections to the engine fuel setting through an actuator connected to the fuel system.

The engine speed is felt by a magnetic pickup. As the teeth of the flywheel go through the magnetic lines of force around the pickup an AC voltage is made. The ratio between the frequency of this voltage and the speed of the engine is directly proportional. An electric circuit inside the control box feels this AC voltage. In response it sends a DC control voltage, inversely proportional to engine speed, to the actuator.

The actuator is connected to the fuel system by linkage. It changes the electrical input from the control box to mechanical output that changes the engine fuel setting. For example, if the engine speed was more than the speed setting, the control box will decrease fuel to the engine.

Kilowatt load sharing between a group of engine driven generator sets is made possible by electric circuits in the control box. The load on each generator in the system is measured constantly by its control box. Loads are compared between control boxes through paralleling wires between all the units on the same bus. From the input of the paralleling wires the load sharing circuits make constant corrections to the control voltages sent to the actuators. This gives kilowatt load sharing.

The rated and low idle engine speeds are set with speed setting potentiometers. An optional remote speed trim potentiometer will give ± 4% speed setting adjustment. The ramp time potentiometer controls the amount of time it takes the engine to go from low idle to rated speed. An oil pressure switch is connected between terminals 14 and 15. This switch is normally open. When the engine oil pressure increases to 6.4 ± 2.7 psi (44 ± 19 kPa) the switch closes. This permits the control to accelerate to rated speed. If the oil pressure decreases to 3.9 ± 3.3 psi (27 ± 23 kPa) the control will return the engine to low idle.

A minimum fuel switch can be connected between terminals 22 and 23. This gives an optional method for shutdown. When this switch is closed the voltage output to the actuator is zero.

The gain and stability potentiometers control the response of the engine to a change in load. The gain potentiometer is used to decrease response time to a minimum. The stability potentiometer is used to get the best speed stability for the gain setting that is used.

ACTUATOR

MAGNETIC PICKUP

The speed droop potentiometer controls the amount of speed droop. It can be set between 0 and 13%. Droop is necessary when paralleling with a utility bus or a unit with a hydra/mechanical governor.

NOTE: Potential Transformer and current transformers must be connected for speed droop to function.

The de-droop potentiometer gives compensation during isochronous operation for droop caused by component tolerances and outside electrical noise. Make adjustments after equipment installation is complete.

The load gain potentiometer is set so that the ratio between the actual kilowatt output and the rated kilowatt output of each unit in the system is the same.

The speed failsafe circuit will return the voltage output of the control to zero if the magnetic pickup signal has a failure. This will cause the actuator to move to the FUEL OFF position. Also the engine will not start if the magnetic pickup signal has a failure.

NOTE: On 7N183 and 7N5581 Control Boxes terminals 12 and 13 are used when the power supply is 24 VDC. When the power supply is 32 VDC terminals 13 and 25 are used.

On the 8N409 Control Box terminals 12 and 13 are used for either 24V or 32 VDC. Terminals 25 of all the units in parallel, are connected together in series. This gives a high voltage selection of all battery voltages. Selection of the high voltage as the common supply to all units prevents small speed changes caused by different battery supply voltages.

For more information, make reference to Special Instruction Form No. SEHS7368.

WIRING DIAGRAM FOR 2301 PARALLEL CONTROL BOX

Fuel System

Governor Air Actuator

AIR ACTUATOR
1. Actuator.

Governor air actuator (1) gives remote control of engine rpm. Air pressure through orifice (2) controls the movement of plunger (3) and rod (5) against spring (4). Rod (5) is connected to the terminal shaft of the governor by linkage. An increase in air pressure moves the rod out to increase rpm. Spring (6) permits the manual control lever to move the terminal shaft instead of the actuator. The diaphragm can be inspected or replaced without a change to the high or low idle speed of the engine.

AIR ACTUATORS
2. Orifice. 3. Plunger. 4. Spring. 5. Rod. 6. Spring.

Fuel Ratio Control

The hydraulic air/fuel ratio control automatically controls the amount of travel of the rack in the FUEL ON direction, until the air pressure in the inlet manifold is high enough to give complete combustion. The air/fuel ratio control keeps engine performance high.

The hydraulic air/fuel ratio control has two valves (1 and 9). Engine oil pressure works against valve (1) to control the movement of the fuel rack. Air pressure from the inlet manifold works against diaphragm (8) to move valve (9) to control oil pressure against valve (1).

When the engine is stopped, there is no pressure on either valve. Spring (7) moves both valves to the ends of their travel. In this position, the fuel rack travel is not restricted. Also in this position, an oil outlet passage (4) is open to let oil away from valve (1).

When the engine is started, the open oil outlet passage (4) prevents oil pressure against valve (1) until air pressure from the inlet manifold is high enough to move valve (9) to close the large oil passage (5). Engine oil pressure then works against valve (1) to move this valve into its operating position. The control will operate until the engine is stopped.

HYDRAULIC AIR/FUEL RATIO CONTROL
1. Valve. 2. Oil inlet passage. 3. Passage for inlet air pressure. 4. Oil outlet passage. 5. Large oil passage. 6. Oil drain. 7. Spring. 8. Diaphragm. 9. Valve.

When the governor control is moved toward the full load position with the engine running, the head on the stem of valve (1) will cause a restriction to the travel of the fuel rack, until the air pressure in the inlet manifold has an increase. As there is an increase in the air pressure in the inlet manifold, this pressure works against diaphragm (8) to cause valve (9) to move to the left. The large oil passage (5) becomes open to let oil pressure away from valve (1), toward spring (7), and out to drain (6). As there is a decrease in oil pressure, valve (1) moves to the left to let the fuel rack open at a rate equal to (the same as) the air available for combustion.

Shutoff And Alarm Systems

Alarm Contactor System

WIRING SCHEMATIC (Typical Example)
1. Oil pressure switch (switch with manual override shown). 2. Water temperature contactor. 3. Source voltage. 4. Toggle switch (optional). 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).

Before the engine is started it will be necessary to override the oil pressure switch (1) or the alarm will activate. This is done by either a manual override button on the oil pressure switch or toggle switch (4). Oil pressure will return the manual override button to the run position. The toggle switch must be manually closed when the engine has oil pressure.

Water Temperature And Oil Pressure Shutoff System

WIRING SCHEMATIC (Typical Example)
1. Oil pressure switch (switch with manual override shown). 2. Water temperature contactor. 3. Oil pressure (time delay) or fuel pressure switch. 4. Rack solenoid. 5. Terminal block. 6. Diode assembly. 7. Starter. 8. Battery.

If the oil pressure is too low or the water 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.

Before the engine can be started it will be necessary to push the manual override button on oil pressure switch (1). Oil pressure will return the manual override button to the run position.

Diode assembly (6) is used to stop arcing, for protection of the system.

Oil pressure delay or fuel pressure switch (3) is used to prevent discharge of battery (8) through the solenoid when the engine is stopped. The optional grounds to engine shown are used with grounded systems only.

Electronic Overspeed Shutoff System

WIRING SCHEMATIC (Typical Example)
1. Rack solenoid. 2. Diode assembly. 3. Oil pressure (time delay) or fuel pressure switch. 4. Overspeed switch. 5. Magnetic pickup. 6. Terminal block. 7. Starter. 8. Battery.

Magnetic pickup (5) sends a voltage to overspeed switch (4). The frequency of this voltage tells the overspeed switch the speed of the engine. If the speed of the engine gets too high the overspeed switch sends a signal to activate rack solenoid (1).

The rack 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.

After an overspeed shutdown the overspeed switch must be reset before the engine can start.

Diode assembly (2) is used to stop arcing, for protection of the system.

If the Woodward 2301 Control System is used only one magnetic pickup is needed. The magnetic pickup is wired to the overspeed switch and from the overspeed switch to the control box.

The optional grounds to the engine shown are used with grounded systems only.

An oil pressure (time delay) or fuel pressure switch (3) is used to prevent discharge of battery (8) through the solenoid when the engine is stopped. The electronic overspeed 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 System

WIRING SCHEMATIC (Typical Example)
1. Oil pressure switch (switch with manual override shown). 2. Water temperature contactor. 3. Oil pressure (time delay) or fuel pressure switch. 4. Overspeed switch. 5. Rack solenoid. 6. Diode assembly. 7. Magnetic pickup. 8. Terminal block. 9. Starter. 10. Battery.

The rack solenoid can be activated by oil pressure switch (1), water temperature contactor (2) or overspeed switch (4). See WATER TEMPERATURE AND OIL PRESSURE SHUTOFF SYSTEM and ELECTRONIC OVERSPEED SHUTOFF SYSTEM.

Electronic Overspeed With Air Shutoff

WIRING SCHEMATIC (Typical Example)
1. Rack solenoid. 2. Overspeed switch. 3. Magnetic pickup. 4. Diode. 5. Diode assemblies. 6. Air shutoff solenoid. 7. Terminal block. 8. Starter. 9. Battery.

This system gives overspeed protection. Air shutoff solenoid (6) controls a valve assembly in the air inlet pipe. When the solenoid is activated the valve closes to shutoff air to the engine. When the engine has an overspeed condition the air shutoff solenoid is activated by the same signal from overspeed switch (2) that activates rack solenoid (1). See ELECTRONIC OVERSPEED SHUTOFF SYSTEM.

Diode assemblies (5) are used to stop arcing, for protection of the system.

Diode (4) keeps the air shutoff solenoid circuit separate from the rack solenoid circuit. For example, if a manual switch was connected to the rack solenoid the air shutoff solenoid would not activate when the switch was closed.

NOTE: If the air shutoff solenoid has been activated it will be necessary to reset the valve assembly before the engine can be started.

Water Temperature, Oil Pressure And Electronic Overspeed With Air Shutoff

WIRING SCHEMATIC (Typical Example)
1. Oil pressure switch (switch with manual override button shown). 2. Water temperature contactor. 3. Oil pressure (time delay) or fuel pressure switch. 4. Overspeed switch. 5. Diode. 6. Diode assemblies. 7. Air shutoff solenoid. 8. Rack solenoid. 9. Magnetic pickup. 10. Terminal block. 11. Starter. 12. Battery.

This system gives high water temperature, low oil pressure and overspeed protection. See WATER TEMPERATURE, OIL PRESSURE AND ELECTRONIC OVERSPEED SYSTEM.

Diode assemblies (6) are used to stop arcing, for protection of the system.

Diode (5) keeps the air shutoff solenoid circuit separate from the rack shutoff solenoid circuit. The air shutoff solenoid can only be activated by the electronic speed switch. If the signal to shutoff the engine comes from any other component only the rack solenoid will activate.

NOTE: If the air shutoff solenoid has been activated it will be necessary to reset the valve assembly before the engine can be started.

Mechanical Oil Pressure And Water Temperature Shutoff

MECHANICAL OIL PRESSURE AND WATER TEMPERATURE SHUTOFF (Typical Illustration)
1. Water temperature shutoff. 2. Shutoff lever. 3. Piston. 4. Port. 5. Spring. 6. Control lever. 7. Oil pressure shutoff.

Oil pressure shutoff (7) is fastened to the governor. Control lever (6) is connected by a shaft to shutoff lever (2). The shutoff lever is connected by linkage to the fuel rack.

Before the engine is started the control lever is used to push the shutoff lever against piston (3). The shutoff lever moves the piston back and puts spring (5) in compression. With the shutoff lever in this position the engine can be started.

When the engine starts, pressure oil will flow through port (4) into the space between the piston and the housing. When the oil pressure is high enough it will hold the piston in position. As long as the engine has enough oil pressure the fuel rack can be controlled by the governor.

If the oil pressure gets too low the force of compression in the spring will move the piston against the shutoff lever. The shutoff lever will move the fuel rack to stop the flow of fuel to the engine. The engine will stop.

Water temperature shutoff (1) is a control valve for the oil pressure shutoff.

When the water temperature becomes too high thermostat assembly (10) causes stem (9) to move ball (11) off of its seat. Pressure oil at inlet port (8) will go through the valve and drain into the engine crankcase. This will cause the oil pressure to decrease. The oil pressure shutoff will activate and stop the engine.

TEMPERATURE SHUTOFF
8. Inlet port. 9. Stem. 10. Thermostat assembly. 11. Ball.

Mechanical Overspeed Shutoff System

The mechanical overspeed switch is fastened to the tachometer drive on the engine. Wires connect the switch to the rack shutoff solenoid.

If the engine speed gets too high the switch contacts will close. This will activate the rack shutoff solenoid. The engine will stop.

MECHANICAL OVERSPEED SWITCH
1. Button.

After the engine is stopped because of an overspeed condition push button (1). This will open the switch and permit the engine to be started.

Shutoff And Alarm System Components

Oil Pressure Switch

Micro Switch Type

The oil pressure switch is used to give protection to the engine from damage because of low oil pressure. When oil pressure lowers to the pressure specifications of the switch, the switch closes and activates the rack shutoff solenoid.

On automatic start/stop installations, this switch closes to remove the starting system from the circuit when the engine is running with normal oil pressure.

This switch for oil pressure can be connected in a warning system for indication of low oil pressure with a light or horn.

As pressure of the oil in bellows (6) becomes higher, arm (4) is moved against the force of spring (3). When projection (10) of arm (4) makes contact with arm (9), pressure in the bellows moves both arms. This also moves button (8) of the micro switch to activate the micro switch.

OIL PRESSURE SWITCH (Micro Switch Type)
1. Locknut. 2. Adjustment screw. 3. Spring. 4. Arm. 5. Spring. 6. Bellows. 7. Latch plate. 8. Button for micro switch. 9. Arm. 10. Projection of arm.

Some of these switches have a "Set For Start" button. When the button is pushed in, the micro switch is in the START position. This is done because latch plate (7) holds arm (9) against button (8) of the micro switch and the switch operates as if the oil pressure was normal. When the engine is started, pressure oil flows into bellows (6). The bellows move arm (4) into contact with latch plate (7). The latch plate releases the "Set For Start" button and spring (5) moves it to the RUN position. This puts the switch in a ready to operate condition.

Earlier Type Switch

Early type switches for oil pressure have a control knob (1). The knob must be turned (reset) every time the engine is stopped. Turn the knob counterclockwise to the OFF position before the engine is started. The knob will move to the RUN position when the oil pressure is normal.

OIL PRESSURE SWITCH (Earlier Type)
1. Control knob.

Pressure Switch

These type pressure switches are used for several purposes and are available with different specifications. They are used in the oil system and in the fuel system. One use of the switch is to open the circuit between the battery and the rack shutoff solenoid after the oil pressure is below the pressure specifications of the switch. It also closes when the engine starts.

Another use of the switch is to close and activate the battery charging circuit when the pressure is above the pressure specification of the switch. It also disconnects the circuit when the engine is stopped.

Some switches of this type have three terminal connections. They are used to do two operations with one switch. They open one circuit and close another with the single switch.

PRESSURE SWITCH

Water Temperature Contactor Switch

The contactor switch for water temperature is installed in the water manifold. No adjustment to the temperature range of the contactor can be made. The element feels the temperature of the coolant and then operates the micro switch in the contactor when the coolant temperature is too high, the element must be in contact with the coolant to operate correctly. If the cause for the engine being too hot is because of low coolant level or no coolant, the contactor switch will not operate.

The contactor switch is connected to the rack shutoff solenoid to stop the engine. The switch can also be connected to an alarm system. When the temperature of the coolant lowers to the operating range, the contactor switch opens automatically.

WATER TEMPERATURE CONTACTOR SWITCH

Shutoff Solenoid

A shutoff solenoid changes electrical input into mechanical output. They are used to move the fuel rack to a no fuel position or to move a valve assembly in the air inlet pipe to a closed position. This stops the engine.

The shutoff solenoid can be activated by any one of many sources. The most usual are: water temperature contactor, oil pressure switch, overspeed switch (electronic or mechanical) and remote manual control switch.

RACK SHUTOFF SOLENOID (Typical Illustration)

Circuit Breaker

The circuit breaker gives protection to an electrical circuit. Circuit breakers are rated as to how much current they will permit to flow. If the current in a circuit gets too high it will cause heat in disc (3). Heat will cause distortion of the disc and contacts (2) will open. No current will flow in the circuit.

An open circuit breaker will close (reset) automatically when it becomes cooler.

CIRCUIT BREAKER SCHEMATIC
1. Disc in open position. 2. Contacts. 3. Disc. 4. Circuit terminals.

Electronic Speed Switch

The electronic speed switch (dual speed switch) activates the shutoff solenoid when the engine speed gets approximately 18% higher than the rated full load speed of the engine. It also causes the starter motor pinion to move away from the flywheel.

NOTE: Some earlier electronic speed switches do not have the crank disconnect.

The electronic speed switch makes a comparison between the output frequency of magnetic pickup (2) and the setting of the electronic speed switch. When they are equal, the normally open contacts in the electronic speed switch close. On earlier models handle (1) moves to the overspeed position. On later models lamp (4) will go on. The switch also has a fail safe circuit that will cause the engine to shutdown if there is an open in the magnetic pickup circuit.

When the engine is stopped by the earlier electronic speed switch it will be necessary to move handle (1) to the run position before the engine can be started. On later model switches push reset button (3).

ELECTRONIC SPEED SWITCH (EARLIER)
1. Handle. 2. Magnetic pickup.

ELECTRONIC SPEED SWITCH (LATER)
3. Reset button. 4. Lamp.

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.

Automatic Start/Stop System (Non-Package Generator Sets)

AUTOMATIC START/STOP SYSTEM SCHEMATIC (Hydraulic Governor)
1. Magnetic pickup. 2. Starter motor and solenoid. 3. Shutoff solenoid. 4. Oil pressure switch. 5. Water temperature switch. 6. Oil pressure time delay switch. 7. Electronic overspeed switch. 8. Battery. 9. Initiating relay (IR). 10. Shutdown relay (SR). 11. Auxiliary relay (AR). 12. Overcrank timer (OCT). 13. Time delay relay (TD). 14. ON/OFF/STOP switch (SW2). 15. AUTOMATIC/MANUAL switch (SW1). 16. Terminal board (TS1).

An automatic start/stop system is used when a standby electric set has to give power to a system if the normal (commercial) power supply has a failure. There are three main sections in the system. They are: the automatic transfer switch, the cranking panel and the electric set.

Automatic Transfer Switch

The automatic transfer switch normally connects the 3-phase normal (commercial) power supply to the load. When the commercial power supply has a failure the switch will transfer the load to the standby electric set. The transfer switch will not transfer the load from commercial to emergency power until the emergency power gets to the rated voltage and frequency. The reason for this is the solenoid that causes the transfer of power operates on the voltage from the standby electric set. When the normal power returns to the rated voltage and frequency and the time delay (if so equipped) is over, the transfer switch will return the load to the normal power supply.

AUTOMATIC TRANSFER SWITCH

AUTOMATIC START/STOP SYSTEM SCHEMATIC (2301 Control System)
1. Magnetic pickup. 2. Starter motor and solenoid. 4. Oil pressure switch 1 (OPS1). 5. Water temperature switch. 7. Electronic overspeed switch. 8. Battery. 9. Initiating relay (IR). 10. Shutdown relay (SR1). 11. Auxiliary relay (AR). 12. Overcrank timer (OCT). 13. Time delay relay (TD). 14. ON/OFF/STOP switch (SW2). 15. AUTOMATIC/MANUAL switch (SW1). 16. Terminal board (TS1). 17. EG-3P Actuator. 18. Oil pressure switch 2 (OPS2). 19. 2301 Control box.

Cranking Panel

The main function of the cranking panel is to control the start and shutoff of the electric set.

BASIC CRANKING PANEL
1. Indicator light. 2. Manual-Automatic switch. 3. ON-OFF-STOP switch.

LOCKOUT indicator light (1) will activate if, the engine does not start, or if a protection device gives the signal to shutoff during operation.

Switch (2) gives either AUTOMATIC or MANUAL starting. In the diagrams shown later this switch is called SW1. Switch (3) has three positions "ON", "OFF" and "STOP". This switch is called SW2 in the diagrams. Move SW2 (3) to ON and SW1 (2) to MAN to start the engine immediately. Move SW2 (3) to OFF on an electric set in operation to start the shutoff sequence. If the system is equipped with a time delay the engine will not stop immediately. When SW2 (3) is moved to the STOP position the engine stops immediately. The switch must be held in the STOP position until the engine stops. When the switch is released a spring returns it to the OFF position. With SW2 (3) in the ON position and SW1 (2) in the AUTO position the control is ready for standby operation.

There are several attachments that can be ordered for this panel. A description of how each one works and the effect it has on the operation of the standard system is given after the explanations of the standard system.

Electric Set

The components of the electric set are: the engine, the generator, the starting motor, the battery, the shutoff solenoid and signal switches on the engine. The electric set gives emergency power to drive the load.

An explanation of each of the signal components is given in separate topics.

Hydraulic Governor Application

The circuit illustrations that follow are basic schematics. DO NOT use them as complete wiring diagrams.

Components of the automatic start/stop system:

Automatic Starting Operations

When emergency power is needed, the initiating contactor closes. This energizes the initiating relay and the run relay. The current flow through the initiating relay contacts then energizes the magnetic switch, which energizes the pinion solenoid. The starting motor is now connected to the battery. The starting operation starts. At the same time the overcrank timer is energized and starts to run.

At 600 rpm the cranking terminate relay closes. Oil pressure causes oil pressure shutdown switch (OPS) to activate. The normally closed contacts open and the normally open contacts close. When oil pressure shutdown switch (OPS) activates, the auxiliary relay is energized and current flow to the magnetic switch and pinion solenoid is stopped. The starting operation then stops.

CONTROL PANEL CONTROLS IN AUTOMATIC POSITION; ENGINE STARTING

CONTROL PANEL CONTROLS IN AUTOMATIC POSITION; ENGINE STARTS

CONTROL PANEL CONTROLS IN AUTOMATIC POSITION: ENGINE DOES NOT START

If the engine does not start in 30 seconds, the overcrank timer contact closes. This energizes the shutdown relay and the alarm light. The shutdown relay stops current flow to the initiating relay and the run relay. De-energizing the run relay also stops current flow to the axiliary relay. When the shutdown relay is energized, the magnetic switch and the pinion solenoid are de-energized. The starting operation then stops. The shutdown relay also energizes the rack solenoid to move the fuel rack to the fuel OFF position. The shutdown relay is energized until switch (SW2) is manually turned to the OFF position.

Automatic Stopping Operations

CONTROL PANEL CONTROLS IN AUTOMATIC POSITION; SHUTDOWN BY PROTECTION COMPONENT

When the contacts for any of the shutdown switches close, the shutdown relay and the alarm light are energized. This de-energizes the initiating relay, run relay and auxiliary relay. The rack solenoid is energized to move the fuel rack to the fuel OFF position. A parallel circuit through the fuel pressure switch and the normally closed contact of the run relay is also completed to the rack solenoid. The shutdown relay is energized until switch (SW2) is manually turned to the OFF position.

When commercial power is started again, the initiating contactor opens. This de-energizes the initiating relay, the run relay and the auxiliary relay. Current then goes through the normally closed contact of the run relay to the rack solenoid. The rack solenoid is energized to move the fuel rack to the FUEL OFF position.

CONTROL PANEL CONTROLS IN AUTOMATIC POSITION; EMERGENCY POWER NOT NEEDED

Manual Starting Operation

CONTROL PANEL CONTROLS IN MANUAL POSITION; ENGINE STARTING

Switch (SW1), in the MANUAL position, removes the initiating contactor from the circuit. In the MANUAL Position the initiating relay and the run relay are energized. This energizes the magnetic switch and the pinion solenoid. The starting motor is now connected to the battery. The starting operation starts. The overcrank timer is not in this circuit, so if the engine does not start, either switch (SW1) or (SW2) must be turned to another position to stop the starting operation. When the engine starts, the magnetic switch and the pinion solenoid are de-energized in the same way they are de-energized when the engine starts in the AUTOMATIC position.

Manual Stopping Operation

CONTROL PANEL CONTROLS IN AUTOMATIC POSITION; MANUAL SHUTDOWN

When switch (SW2) is moved to the STOP position, current flow is directly to the rack solenoid. The rack solenoid moves the fuel rack to the fuel OFF position. The initiating relay, run relay and auxiliary relay are de-energized. Switch (SW2) must be held in the STOP position until the engine stops.

2301 Control System Application

The circuit illustrations that follow are basic schematics. DO NOT use them as complete wiring diagrams.

Components of the automatic start/stop system:

Components of the 2301 control system:

Automatic Starting Operations

When emergency power is needed, the initiating contactor closes. This energizes the initiating relay, the cranking relay, and connects the 2301 Governor to the battery. The cranking relay energizes the magnetic switch and the pinion solenoid. The starting motor is now connected to the battery. The starting operation starts. At the same time the overcrank timer is energized and starts to run.

CONTROL PANEL CONTROLS IN AUTOMATIC POSITION; ENGINE STARTING

At 600 rpm the cranking terminate relay closes. Oil pressure switch (OPS2) closes at approximately 6.4 psi (44 kPa). This lets the 2301 control signal the actuator to move from low idle to the desired rpm. Oil pressure also causes oil pressure shutdown switch (OPS1) to activate. The normally closed contacts open and the normally open contacts close. When oil pressure shutdown switch (OPS1) activates, the auxiliary relay is energized and current flow to the cranking relay stops. This de-energizes the magnetic switch and the pinion solenoid. The starting operation stops.

If the engine does not start in 30 seconds, the overcrank timer contact closes. This energizes the shutdown relay and the alarm light. The shutdown relay stops current flow to the initiating relay. The current flow is then stopped to the 2301 Control. The EG-3P Acuator moves the fuel rack to the FUEL OFF position. This also de-energizes the magnetic switch and the pinion solenoid. The starting operation stops. The shutdown relay is energized until switch (SW2) is manually turned to the OFF position.

CONTROL PANEL CONTROLS IN AUTOMATIC POSITION; ENGINE STARTS

CONTROL PANEL CONTROLS IN AUTOMATIC POSITION; ENGINE DOES NOT START

Automatic Stopping Operations

When the contacts for any of the shutdown switches close, the shutdown relay and the alarm light are energized. This de-energizes the initiating relay and the auxiliary relay. Current flow to the 2301 Control is stopped. The EG-3P Actuator will then move the fuel rack to the FUEL OFF position. The shutdown relay is energized until switch (SW2) is manually turned to the OFF position.

CONTROL PANEL CONTROLS IN AUTOMATIC POSITION; SHUTDOWN BY PROTECTION COMPONENT

CONTROL PANEL CONTROLS IN AUTOMATIC POSITION; EMERGENCY POWER NOT NEEDED

When commercial power is started again, the initiating contactor opens. This de-energizes the initiating relay and the auxiliary relay. Current flow to the 2301 Control is stopped. The EG-3P Actuator will then move the fuel rack to the fuel OFF position.

Manual Starting Operation

Switch (SW1), in the MANUAL position, removes the initiating contactor from the circuit. In the MANUAL position the initiating relay is energized and current goes to the 2301 Control. The current flow through the initiating relay contacts also energizes the cranking relay. The cranking relay energizes the magnetic switch which in turn energizes the pinion solenoid. The starting motor is now connected to the battery. The starting operation starts. The overcrank timer is not in this circuit, so if the engine does not start, either switch (SW1) or (SW2) must be moved to another position to stop the starting operation. When the engine starts, the magnetic switch and the pinion solenoid are de-energized in the same way as they are de-energized when the engine starts in the Automatic Starting Operation.

CONTROL PANEL CONTROLS IN MANUAL POSITION; ENGINE STARTING

Manual Stopping Operation

When switch (SW2) is moved to the STOP position, current flow to the 2301 Control is stopped. The EG-3P Actuator will then move the fuel rack to the FUEL OFF position. The initiating relay and auxiliary relay are also de-energized. Switch (SW2) must be held in the STOP position until the engine stops.

CONTROL PANEL CONTROLS IN AUTOMATIC POSITION; MANUAL SHUTDOWN

Attachments For Cranking Panel

Separate Alarm Lights

SEPARATE ALARM LIGHTS

This attachment shows the reason for shutdown.

Cycle Cranking Timer

The cycle cranking timer has a cycle crank module (CC). It permits adjustment of the amount of time that the starting motor operates. It can be set for 30 seconds of constant operation to 5 cycles of 10 seconds of operation with a 10 second delay between each cycle of operation. When the cranking cycles set in the timer are completed, cycle crank module (CC) closes the circuit to the overcrank relay (OCT).

Time Delay Relay

This attachment causes a 2 minute delay in the activation of the shutoff solenoid (RS) when the engine is automatically being stopped because of the return of (commercial) normal power.

The purpose of this time delay is to let the engine cool more slowly after running.

When the (commercial) normal power starts again, the initiating contactor (I) opens. This opens the circuit to the run relay (RR) and initiating relay (IR). The run relay (RR) has normally closed contacts which connect the oil pressure time delay switch (OPTD) with the time delay relay (TD). The oil pressure time delay switch (OPTD) is closed at this time. The time delay relay (TD) starts to measure time. After 2 more minutes of engine operation, the time delay relay (TD) activates. It closes its normally open contacts in the circuit between the oil pressure time delay switch (OPTD) and the shutoff solenoid (RS). Because the oil pressure time delay switch (OPTD) is closed, the circuit is now closed to the shutoff solenoid (RS). The shutoff solenoid (RS) activates. It moves the fuel rack to the FUEL OFF position. This makes the engine stop running.

If the (commercial) normal power stops before the engine stops turning, the engine can start running again immediately. This is because the initiating contactor (I) closes again. This closes the circuit to run relay (RR) and initiating relay (IR). The run relay (RR) activates and opens its normally closed contacts in the circuit with the time delay relay (TD). The time delay relay (TD) is now disconnected so it opens its normally open contacts in the circuit with the shutoff solenoid (RS). The shutoff solenoid (RS) releases the fuel in the fuel injection pump. The governor now controls the fuel supply to the engine. The governor gives the engine more fuel to make the speed increase to the correct speed for the engine.

If the initiating contactor (I) closes just as the engine stops turning, the starting motor can activate almost immediately. This is because the oil pressure switch (OPS) is activated by engine oil pressure. When the engine stops running, the oil pressure decreases faster than the engine stops its motion. If the engine does not start running again because of the force of rotation of the flywheel, the engine oil pressure does not increase to activate the oil pressure switch (OPS). If the oil pressure switch (OPS) does not activate, the starting motor (SM) activates when the initiating relay (IR) closes its contacts.

SCHEMATIC OF CONTROL PANEL (SHOWS ALL STANDARD ATTACHMENTS) (ALL COMPONENTS ARE SHOWN IN NORMAL CONDITIONS)

The components are: