Systems Operation

Usage:

Woodward PSG Governor

This a diesel engine presentation; for Natural Gas engines, substitute "carburetor throttle" where "fuel rack" is mentioned.

The oil supply is from the engine lubrication system. This oil is supplied to the governor oil pump which boosts it to 175 psi (12,3 kg/cm²). Four check valves permit rotation of the governor in either direction. Relief valve discharge is back to supply, so unused oil is recirculated within the governor.

GOVERNOR OIL FLOW SCHEMATIC

The governor drive shaft is hydraulic valve bushing (7). Pilot valve plunger (5), in the hollow center of the bushing, screws into thrust bearing and spring seat (2). The bushing drives weights (1); the toes of the weights rest against the thrust bearing and spring seat. One of hydraulic pump gears (9) is integral with bushing (7).

When the load on the engine increases, the rpm of the engine decreases and the rotating speed of governor weights (1) decreases. Governor weight centrifugal force is less and governor spring (3) pushes spring seat (2) and pilot valve plunger (5) to a position in bushing (7) where an oil passage is opened and oil is directed to power piston (6). The pressure of the oil moves the power piston which moves lever (4). The lever is the part of the governor terminal shaft which is linked to the engine fuel rack. The fuel rack is moved to a more fuel position and the rpm of the engine increases. As the engine rpm increases, governor weights (1) rotate faster, centrifugal force is greater and the toes of the weights move thrust bearing and spring seat (2) connected to pilot valve plunger (5). When the rpm of the engine is again the same as it was before the load increased, the governor weights will have moved the pilot valve plunger to its original position, closing the oil passage to power piston (6) to stop the movement of the power piston and engine fuel rack.

When the load on the engine decreases, the rpm of the engine increases and the rotating speed of governor weights (1) increase. The toes on the governor weights move thrust bearing and spring seat (2) and pilot valve plunger (5) to a position in bushing (7) that allows the oil under power piston (6) to drain. When the oil under the power piston can drain, a spring in the governor linkage (not part of the governor) moves the engine fuel rack to a lesser fuel position and the rpm of the engine decreases. The governor weights rotate slower and governor spring (3) pushes on spring seat (2) and pilot valve plunger (5). When the rpm of the engine is again the same as it was before the load decreased, the governor spring will have pushed the pilot valve plunger to a position where oil can no longer drain from under power piston (6) and the movement of the power piston and fuel rack is stopped.

HYDRAULIC GOVERNOR-CROSS SECTION
1. Weights (two in ball head assembly). 2. Thrust bearing and spring seat. 3. Governor spring. 4. Lever (terminal shaft). 5. Pilot valve plunger. 6. Power piston. 7. Bushing (drive shaft). 8. Buffer piston. 9. Hydraulic pump gears. 10. Buffer springs (two).

The sensitivity of governor weights (1) and governor spring (3) to the slightest variations in engine rpm are absorbed by buffer springs (10) that center buffer piston (8) in power piston (6). The oil directed to the power piston must first pass through an opening in the bottom of the power piston and act on the buffer piston to move the power piston.

The hydraulic governor is a zero percent speed droop governor (isochronous). Speed droop is the percent difference between the rpm of an engine operating under no load and the rpm of an engine operating under full load. The percent of speed droop is calculated by using the following equation.

Woodward UG-8 Governor

(Electric set application when frequency control is critical.)

There is no direct mechanical link between the flyweights and fuel rack. Rack movement is accomplished by a hydraulic piston which is pilot operated by combined action of the governor flyweights and a compensating piston.

GOVERNOR CONTROLS
1. Synchronizing motor. 2. Synchronizer knob. 3. Speed droop knob. 4. Compensating pointer. 5. Synchronizer indicator. 6. Load limit knob. 7. Plug.

Engine rpm is controlled by changing the compression of the flyweight spring. An A.C. motor (1) mounted to the top of the governor provides for remote control of the spring. A synchronizer knob (2) on the governor dial panel provides control of the same function (engine rpm). The synchronizer indicator (5) directly below the synchronizer knob, indicates the number of synchronizer knob revolutions and resulting spring compression.

A speed droop knob (3) provides a means of changing the difference between FULL LOAD RPM and HIGH IDLE (unloaded) RPM. Any difference between HIGH IDLE RPM and FULL LOAD RPM is called "DROOP" and this difference in rpm divided by the FULL LOAD RPM is called "DROOP PERCENTAGE." At zero droop the UNLOADED and LOADED RPM are equal. Providing droop control allows the use of two or more electric sets to power a common load (in parallel). Only one of the paralleled electric sets (with zero droop) senses the variation in power demand and immediately provides the increase or decrease in power while the electric set or sets with high droop governors carry a fixed output.

A load limit knob (6) is for the operator to manually limit the engine rpm. This knob provides a positive stop to linkage movement, and provides a quick means of local engine shut off. The engine can be idled to allow slow cooling of the systems and then shut off by turning the load limit body first partially and then completely to zero.

A compensator adjustment is provided to adjust the governor sensitivity. Detailed information concerning governor adjustments is provided in the TESTING AND ADJUSTING section of this manual.

Plug (7) covers a needle valve adjustment screw that allows the technician to bleed air from the governor hydraulic system at initial installation or during lubrication changes. Loosening the screw causes the hydraulic components to reciprocate more rapidly and purge air to the sump. Final adjustment of the needle valve controls governor response. Compensating pointer (4) provides for governor sensitivity adjustment.

Pierce Output Shaft Governor

OUTPUT SHAFT GOVERNOR AND HYDRAULIC SERVO MECHANISM
1. Flexible drive cable. 2. Output shaft governor. 3. Terminal lever. 4. Rocker shaft. 5. Rate adjusting screw. 6. Speed change lever. 7. Governor spring. 8. Bumper screw. 9. Link. 10. Actuating lever. 11. Rocker shaft lever. 12. Low speed adjusting screw. 13. High speed adjusting screw. 14. Bracket.

The output shaft governor (2) is driven by a flexible cable assembly (1) which connects to the governor drive mechanism on the torque converter. The output shaft governor (2) and hydraulic servo mechanism are connected by means of an adjustable link (9).

The output shaft governor acts as an "assistant operator," automatically reducing engine speed, which in turn reduces converter output shaft speed whenever the load on the converter output shaft decreases. Thus, it acts as a speed limiting device by preventing the output shaft and driven equipment from suddenly and perhaps dangerously, overspeeding. This also relieves the operator of making speed adjustments through the engine governor.

The torque converter output shaft maximum speed is either a high speed setting or a low speed setting, which is determined by changing the position of speed change lever (6), normally be remote control. High speed screw (13) determines the maximum speed for the high speed setting, and low speed screw (12) determines the maximum low speed setting. In other words, for either setting there is a predetermined maximum speed which the output shaft cannot exceed.

The operation of the governor is the same as most rotating weight-type governors. The governor operates only when the torque converter output shaft attempts to exceed a predetermined maximum speed. This speed is determined by the amount of tension placed on governor spring (7). On a variable speed governor, the spring tension is controlled by rate adjusting screw (5) and the position of the speed change lever. Increasing the spring tension increases the maximum speeds.

When the output shaft speed approaches the predetermined governed speed setting, weights (15) are forced out moving thrust sleeve (17) and bearing assembly (18) against the rocker yoke (19). As the output shaft speed reaches the predetermined governor speed setting, the force of the weights overcomes the force of the governor spring and the rocker yoke is moved rotating the rocker shaft (4). Linkage attached to the rocker shaft overrides the diesel engine governor and reduces engine speed which in turn reduces converter output shaft speed. As the rocker yoke moves outward, it contacts small bumper spring (16) in the end of the governor body, which dampens oscillation of the yoke preventing erratic governor control. A bumper screw positions the bumper spring.

As torque converter output shaft speed drops below the maximum governed speed limit, the force exerted by the output shaft governor weights is reduced. Since the governor is then no longer effective, the diesel engine governor takes over full engine control and increases engine speed toward its full governed setting.

The terminal lever (3) mounted on the rocker shaft is connected to the hydraulic servo mechanism by the adjustable link (9) and actuating lever (10). Any movement of the rocker shaft is thus transmitted to the hydraulic servo mechanism.

OUTPUT SHAFT GOVERNOR OPERATION
15. Weight. 16. Bumper spring. 17. Thrust sleeve. 18. Bearing assembly. 19. Rocker yoke.

The hydraulic servo mechanism consists essentially of a servo piston (24), control valve and the necessary connecting linkage. The piston fits into the cylinder bore. It is connected to the actuating lever by shaft (20) link (21) and lever (22).

Oil, delivered from the engine oil pump, flows into the servo mechanism and normally flows through the piston, valve and back to the crankcase. When the output shaft governor takes effect, due to an increase in the torque converter output shaft speed, the governor linkage moves the control valve in the piston. The flow of oil through the piston is blocked and results in an oil pressure build-up. This pressure moves the piston to follow the movement of the valve. This movement continues until the piston ports are uncovered and oil flows through the piston once again.

GOVERNOR SERVO MECHANISM
20. Shaft. 21. Link. 22. Lever. 23. Shaft. 24. Piston. 25. Cam.

The piston movement is transmitted to cam (25), shaft (23) and the governor linkage, and in turn decreases the amount of fuel being delivered to the engine.

When the load on the output shaft is increased, the output shaft speed is reduced and the force exerted by the output shaft governor weights decreases. The force exerted by the output shaft governor spring then overcomes the force exerted by the weights and the actuating linkage moves the servo mechanism valve into the piston. The movement of the valve into the piston uncovers dump ports and allows oil to flow unrestricted through the servo mechanism. The valve and piston are inactive and then the diesel engine governor takes over full control of the engine and the fuel rack moves in the direction of increased fuel, increasing engine speed to its full governed speed.

The whole operational sequence of the torque converter governor overriding the diesel engine governor and then relinquishing control again to the engine governor occurs each time the load variations are severe enough to permit the output shaft speed to increase or decrease and activate the output shaft governor.

Governor Air Actuators

The governor air actuator gives remote control of variable speed for the engine. The actuator operates on air pressure. Air pressure on the cup in the actuator moves the plunger, spring and rod. This motion controls the governor through the linkage.

2N6006 AIR ACTUATOR
1. Linkage.

The actuator connects directly to the governor terminal shaft through linkage (1). Inspection or replacement of the diaphragm without changing the adjustment of the high or low idle speeds or the spring preload is possible.

Prelubrication System

In the prelubrication system, (air start) an air driven prelubrication pump (1) fills the lubrication system to prevent possible damage when the engine is started. When the balanced whistle valve (7) is open, air from the auxiliary air compressor is sent from air valve (3) through line (2) to the prelubrication pump. When the oil pressure is 2.5 psi (0,18 kg/cm²), oil from a connection in the passage cover at the top of the flywheel housing activates air valve (4) which stops air flow at air valve (3) to the prelubrication pump. The valve (3) then sends air to the starting motor. Air pressure for valve (4) is taken from a connection (6) through line (5).

PRELUBRICATION SYSTEM
1. Prelubrication pump. 2. Air line. 3. Air valve. 4. Air valve. 5. Airline. 6. Connection. 7. Balanced whistle valve.

Air Starting System

AIR STARTING SYSTEM
1. Balanced whistle valve. 2. Oiler. 3. Air motor.

The air starting system is mounted on the flywheel housing. Air for the starting system is furnished by an auxiliary air compressor. Air is delivered through a receiver to a remotely mounted pressure regulating valve where the pressure is regulated to suitable starting pressure.

The balanced whistle valve (1) controls the passage of air to the air motor (3). As the air passes through the oiler (2), it picks up oil spray which is deposited on the rotor and vanes of the air motor.

FLOW OF AIR THROUGH STARTING MOTOR (VIEWED FROM DRIVE END OF MOTOR)

Oiler

An air director tube in the air passage through the body delivers pressure above the oil in the bowl. Oil flows from the bowl through a tube and drilled passage to a chamber under the top plug on the body. From the chamber, oil flows through the oil drip gland which meters the flow of oil to about four drops per minute.

Hydraulic Starting

HYDRAULIC START DIAGRAM

Hydraulic cranking systems operate on the principle of pressure oil turning a fluid motor to produce mechanical energy. The oil is stored in a pre-charged, piston-type accumulator and is admitted to the hydraulic cranking motor through a starter control valve. The oil enters the motor through an inlet port and is directed against a series of pistons located within a cylindrical rotor. When the pistons receive the pressurized oil, they move against an angularly mounted fixed thrust bearing. As they contact the bearing they slide downward around the race carrying the rotor with them, causing it to turn. After discharging its work load the oil is returned through the motor outlet port to the oil reservoir.

The engine pump system includes equipment for automatically recharging the accumulator, namely an engine belt driven hydraulic pump with unloading valve and high pressure filter.

The hand pump is for emergency use if accumulator supply is exhausted.

HYDRAULIC MOTOR

Automatic Start-Stop System (Single Unit Applications)

AUTOMATIC START-STOP SYSTEM COMPONENT LOCATION DIAGRAM WITH HYDRAULIC GOVERNOR

This topic describes two typical arrangements of automatic start-stop systems. The first describes an application using a hydraulic governor. The second describes an application using the 2301 Electric Governing System. The 2301 Electric Governing System is sophisticated and complex particularly when used with multiple unit (load sharing) arrangements. Because of the complexity, the multiple unit arrangement is not covered in complete detail, however, connections of engine mounted controls are shown in the topics - 2301 ELECTRIC GOVERNING SYSTEM APPLICATIONS and WIRING DIAGRAMS.

The system automatically starts an unattended engine and takes over the electrical or mechanical load from the commercial power source. Also, the engine automatically shuts down, either after the load is transferred back to the commercial power source, or in the event of high water temperature, low oil pressure or an overspeed condition while the engine is running.

NOTE: The natural gas engine automatic start-stop system operates similarly. The obvious difference is that engine shutdown is accomplished by grounding the ignition system and a solenoid operated valve closing the fuel supply line.

The automatic start-stop system contains three main wiring circuits:

Commercial power source

Electric set or power unit

Cranking panel, starting motor and battery

AUTOMATIC START-STOP SYSTEM COMPONENT LOCATION DIAGRAM WITH 2301 ELECTRIC GOVERNING SYSTEM

TRANSFER SWITCH

The three circuits terminate at the automatic transfer switch. This is a throw-over switch between the load and the electrical power source.

A relay in the transfer switch, activated by commercial power, closes when commercial power source is interrupted and the diesel engine starting operation begins.

The diesel electric set then supplies emergency power during the commercial power interruption. When commercial power is restored, it is automatically connected to the load by the transfer switch and the diesel engine shuts down.

Start-stop components on engines equipped with the start-stop system include:

Each of the engine mounted shutoff components are explained and illustrated in separate topics.

The remote mounted cranking panel consists of the following:

Overcrank timer

Lockout light which indicates the engine has shut down due to a fault.

Initiating, cranking, shutdown and auxiliary relays

On-off-stop toggle switch

Manual-automatic switch

Terminal strip

Electric Governor

AUTOMATIC START-STOP CRANKING PANEL (Typical Illustration)
1. Signal lamp. 2. Manual-automatic switch. 3. On-off-stop switch.

The standard cranking panel has an on-off-stop switch, manual-automatic switch and a single red lens to signal a safety shutdown regardless of cause. Attachments to the cranking panel are discussed after standard panel operations are covered. The internal components are keyed to illustrations as follows:

Hydraulic Governor Application

These illustrations are intended as diagrammatic representations of the operation of the standard cranking panel equipped with RR relay. They are NOT intended to be used as complete wiring diagrams.

D343 ENGINE CONTROL PANEL SET FOR AUTOMATIC START-STOP CONTROL (Switch SW-2 at "ON" and Switch SW-1 at "AUTO") (Control Panel Equipped with RR Run Relay)

Automatic Cranking Operations

1. When engine is required to start, customer-furnished initiating contacts close, thus energizing initiating relay. Magnetic switch is energized through IR and AR contacts. Magnetic switch connects starting motor to battery. Cranking begins. At same time overcrank timer is energized and begins to run.

CONTROL PANEL SATISFYING AUTOMATIC OPERATION DEMAND (Switch SW-2 at "ON" and Switch SW-1 at "AUTO")

CONTROL PANEL STOPPING CRANKING AFTER START (Signalled by Oil Pressure Contactor)

2. When engine starts and normal oil pressure builds up, one set of oil pressure contacts close, energizing auxiliary relay which interrupts current flow to magnetic switch. Magnetic switch opens, interrupts current flow to starting motor and cranking action stops.

CONTROL PANEL STOPPING CRANKING WHEN ENGINE DOES NOT START (Signalled by Overcranking Timer)

3. If engine does not start normally in 30 seconds, overcrank timer contacts close energizing shutdown relay and lighting alarm lamp. Operation of shutdown relay interrupts current flow to initiating relay which opens and stops cranking action. Shutdown relay remains energized until switch SW-2 is manually turned to "OFF" position.

Automatic Stopping Operations

CONTROL PANEL CALLING FOR ENGINE SHUTDOWN (Signalled by Engine Mounted Trouble Sending Units)

1. When engine mounted water temperature, oil pressure and/or overspeed contactors close, current flows through solenoid of shutdown relay which energizes shutoff circuit and alarm lamp is lit. Current flows through contacts of shutdown relay to rack solenoid which closes engine fuel rack. A paralled circuit through the fuel pressure switch flows through the run relay contacts to the rack solenoid. Shutdown relay remains energized until SW-2 is manually moved to OFF position.

CONTROL PANEL CALLING FOR ENGINE SHUTDOWN-EMERGENCY POWER NOT REQUIRED (Signalled by Initiating Contactors)

2. Customer-furnished initiating contacts open, interrupting current flow to initiating relay and run relay which opens normally open IR contacts and closes normally closed RR contact. Current flows through contacts of run relay to rack solenoid which closes engine fuel rack.

Manual Starting

CONTROL PANEL MANUAL STARTING OPERATION (SW-2 at "ON" and SW-1 at "MAN")

Switch SW-1 contacts bypass initiating contacs so initiating relay energizes, and through its contacts, magnetic switch is energized. Magnetic switch closes and cranking action begins. Note that switching of SW-1 to the manual position removes overcrank timer from circuit so if engine does not start, cranking will contine until switches SW-2 or SW-1 are operated to another position.

Manual Stopping

CONTROL PANEL EMERGENCY STOP FUNCTION (SW-2 Operated to "STOP" Position, SW-1 at Any Position)

Current flows directly to rack solenoid which closes engine fuel rack. Current flow to all other relays in cranking panel is interrupted so cranking action, if in progress, is halted. SW-2 switch control stop position is spring loaded and must be held at stop to halt cranking or stop engine.

2301 Electric Governing System Application

This configuration includes an electric governing system. This system involves both engine mounted and remotely mounted controls, however, the complete governing system operation is discussed first.

The Woodward 2301 Electric Governor is used in conjunction with the Woodward EG-3P actuator and a magnetic speed sensing pickup to achieve precise governing. It can be operated as an isochronous governor or as a speed droop governor. As an isochronous governor it maintains a constant speed for all loads within the capacity of the engine.

The 2301 Electric Governor is a compact assembly of solid-state components. It regulates a power supply input of 12, 24, or 32 volts D.C. to maintain a constant voltage for the amplifier section. It will sense engine speed changes and provide a voltage signal proportional to fuel correction required to the hydraulic actuator to maintain set speed. Only two adjustments, gain and reset rheostats, are required for stable control.

The EG-3P Actuator supplies the force needed to move the fuel rack or carburetor throttle. It develops hydraulic pressure by the use of its own gear pump operating from a drive achieved in adapting the actuator to the engine. The oil used in the actuator is common with the engine lubrication system. An oil sump has been incorporated in the oil supply line to the actuator to assure a ready supply of oil at startup.

The EG-3P is a proportional actuator designed to move its terminal shaft from the maximum to the minimum fuel position proportional to the magnitude of the input current. Temperature will not affect its accuracy. The actuator will move to minimum fuel position upon loss of power supply to the 2301 Electric Governor control or loss of signal to the actuator. Interrupting either of these circuits can be used as a means of shutting down the engine. Earlier arrangements will go to maximum fuel position upon loss of power supply or signal to the actuator. This is why they need to be equipped with an overspeed shut down device.

SINGLE UNIT 2301 ELECTRIC GOVERNOR CONNECTIONS TO ENGINE MOUNTED CONTROLS
1. Junction box on engine. 2. OPS2 Oil pressure switch. 3. Wire. 4. EG-3P Governor actuator connector. 5. Electric governor terminal strip. 6. Terminal strip on engine. 7. Magnetic speed sensing pickup. 8. Negative direct current supply from battery of either 32V, 24V or 12V. NOTE: Ground shielded cables at governor control grounding stud.

MULTIPLE UNIT LOAD SHARING, 2301 ELECTRIC GOVERNOR CONNECTIONS TO ENGINE CONTROLS
1. Electric governor terminal strip. 2. Positive DC supply for 32V system. 3. Ground shielded cable at governor control ground stud. 4. Magnetic speed sensing pickup. 5. Engine mounted terminal strip. 6. Positive DC supply for 24V system. 7. Negative DC supply from battery of either 32V or 24V. 8. EG-3P Governor actuator connector. 9. Wire.

WOODWARD EG-3P ACTUATOR (Maximum Fuel Position)

The Magnet Speed Sensing Pickup is mounted in the engine flywheel housing perpendicular to the ring gear teeth. As the ring gear teeth enter and leave the magnetic field, a D.C. voltage is produced within the magnetic pickup assembly which is proportional to engine speed.

This voltage is communicated to the 2301 Electric Governor by means of a shielded and grounded cable. The cable shield should be grounded to the engine at the magnetic pick up connector. The battery negative should share a common ground with the engine.

SENSING PICKUP

By using a magnetic pickup, the 2301 Electric Governor has the ability to function without the presence of the generator. Engine tests can be conducted prior to generator mounting.

The following description of operation refers to illustrations for the D346 and D348 Engines. These illustrations are intended as diagrammatic representations of the operation of the standard cranking panel equipped with a 2301 Electric Governor. They are NOT intended to be used as complete wiring diagrams.

D346 and D348 ENGINE CONTROL PANEL SET FOR AUTOMATIC START-STOP CONTROL (Switch SW-2 at "ON" and Switch SW-1 at "AUTO")

Automatic Cranking Operations

1. When engine is required to start, customer-furnished initiating contacts close, thus energizing initiating relay. Magnetic switch is energized through CR contacts. Magnetic switch connects starting motor to battery. Cranking begins. At same time overcrank timer is energized and begins to run.

CONTROL PANEL SATISFYING AUTOMATIC OPERATION DEMAND-CRANKING (Switch SW-2 at "ON" and Switch SW-1 at "AUTO")

2. When engine starts and normal oil pressure builds up, one set of oil pressure contacts close, energizing auxiliary relay which interrupts current flow to cranking relay which in turn de-energizes magnetic switch. Magnetic switch opens, interrupts current flow to starting motor and cranking action stops.

CONTROL PANEL STOPPING CRANKING AFTER START (Signalled by Oil Pressure Contactor)

CONTROL PANEL STOPPING CRANKING WHEN ENGINE DOES NOT START (Signalled by Overcranking Timer)

Automatic Stopping Operations

1. When engine mounted water temperature, oil pressure and/or overspeed contactors close, current flows through solenoid of shutdown relay which energizes shutoff circuit and alarm lamp is lit. Current flows through contacts of shutdown relay to open the battery circuit to 2301 Electric Governor which stops the engine. Shutdown relay remains energized until SW-2 is manually moved to OFF position.

CONTROL PANEL CALLING FOR ENGINE SHUTDOWN (Signalled by Engine Mounted Trouble Sending Units)

2. Customer-furnished initiating contacts open, interrupting current flow to initiating relay which opens normally open IR contacts. The battery circuit is opened to 2301 Electric Governor and engine is stopped.

CONTROL PANEL CALLING FOR ENGINE SHUTDOWN-EMERGENCY POWER NOT REQUIRED (Signalled by Initiating Contactors)

Manual Starting

CONTROL PANEL MANUAL STARTING OPERATION (SW-2 at "ON" and SW-1 at "MAN")

Switch SW-1 contacts bypass initiating contacts so initiating relay energizes, and through its contacts, magnetic switch is energized. Magnetic switch closes and cranking action begins. Note that switching of SW-1 to the manual position removes overcrank timer from circuit so if engine does not start, cranking will continue until switches SW-2 or SW-1 are operated to another position.

Manual Stopping

CONTROL PANEL EMERGENCY STOP FUNCTION (SW-2 Operated to "STOP" Position, SW-1 at Any Position)

The battery circuit is opened to 2301 Governor to stop engine. Current flow to all relays in cranking panel is interrupted so cranking action, if in progress, is halted.

Attachments For Control Panel

With this attachment the reason for a safety shutdown is readily apparent through lighting of a particular indicator lamp.

Time Delay Relay

Permits the engine to run for two minutes after the load is removed, thus allows for slower cooling. Relay also prevents cranking panel from being thrown out of circuit if it receives start signal while it is shutting down. This condition might occur when commercial power fluctuates every few seconds. Standard cranking panel shuts engine down immediately when load is removed.

CONTROL PANEL OPTIONAL (A separate lamp for each type of shutdown.)

Cycle Cranking Timer

A diaphragm return solenoid and an air bleed through the spring loaded diaphragm give the cycle cranking timer five, ten second cycles, with a ten second delay between cranks. The standard cranking panel provides only a single cranking cycle of 30 seconds duration.

Wiring Diagrams

Wiring Diagrams For Engine Mounted Controls

AUTOMATIC START-STOP ENGINE CONTROLS (Earlier Control for D343 Engines)

Each wire on engine mounted terminal strip must have a marker on both ends corresponding to the terminal number on the terminal strip. Some contactors and switches may be marked to identify C (common), NC (normally closed) and NO (normally open). Those terminals not marked will require identification with a continuity tester or by observation to be sure of proper connection.

AUTOMATIC START-STOP ENGINE MOUNTED CONTROLS (Later Control for D343 Engines)
1. Magnetic switch. 2. Battery. 3. Water Temperature contactor. 4. Rack solenoid. 5. Oil pressure contactor. 6. Overspeed contactor. 7. Circuit breaker. 8. Starting motor. 9. Governor synchronizer motor. 10. Fuel pressure contactor. 11. Connections to cranking panel. 12. Terminal strip.

AUTOMATIC START-STOP ENGINE CONTROLS (Single Unit With Woodward 2301 Electric Governing System and Earlier Starting Motors)

AUTOMATIC START-STOP ENGINE CONTROLS (Single Unit With Woodward 2301 Electric Governing System and Later Starting Motors)
1. Magnetic switch. 2. Battery. 3. Wire. 4. Water temperature contactor. 5. EG-3P Governor actuator. 6. OPS1 Oil pressure contactor. 7. Overspeed contactor. 8. Circuit breaker. 9. Starting motor. 10. OPS2 Oil pressure contactor. 11. Connections to cranking panel. 12. Terminal strip. 13. Shielded cable to 9 and 10 connections on 2301 control. Earlier installations used unshielded cable from OPS2 to TS1 11 and 12. Ground shielded cable at governor ground stud.

TYPICAL DIAGRAM LATER TYPE MULTIPLE UNIT AUTOMATIC START-STOP GAS ENGINE CONTROLS (Load sharing Woodward 2301 Governing System)
1. Magnetic switch. 2. Battery. 3. EG-3P Governor actuator. 4. TS2 Terminal strip. 5. Connections to cranking panel. 6. OPS2 Oil pressure contactor.^* 7. Temperature contactor. 8. OPS1 Oil pressure contactor. 9. Circuit breaker. 10. Starting motor. 11. Overspeed contactor. 12. TS1 Terminal Strip. 13. Connections to cranking panel. 14. Magneto.^** 15. Gas valve.

^*Applications for load sharing use (NO) normally open OPS2, while single unit or applications for standby use (NC) normally closed OPS2.

^**On engines with a single magneto, connect TS1 terminal 11 to engine ground. On engines with two magnetos connect second magneto to TS1 terminal 11.

EARLIER MULTIPLE UNIT AUTOMATIC START-STOP G343 ENGINE CONTROLS (Load Sharing Woodward 2301 Electric Governing System)

WOODWARD SYNCHRONIZING MOTOR DIAGRAM
1. Single pole double throw switch. 2. Red wire connect to switch terminal marked "R" for UG8 Governors or to "L" for PSG Governors. 3. Reversible, 110 V, AC or DC motor. 4. Blue wire marked "C", connected to 110 V, AC or DC supply (14 gauge wire recommended). 5. Black wire connect to switch terminal marked "L" for UG8 Governors or to "R" for PSG Governors.

Safety Devices - (Engine Mounted Controls)

Water Temperature Contactor Switch

A water temperature sending unit 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 no 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.

WATER TEMPERATURE CONTACTOR SWITCH

Shut-Off Solenoid

The shutoff solenoid, when energized moves to over ride the governor action, which in turn moves the governor and fuel rack to the shutoff position. The solenoid can be energized by any one of several sources. The most usual are: water temperature contactor switch, oil pressure contactor switch, overspeed contactor switch and remote manual control switch.

RACK SHUTOFF SOLENOID

Overspeed Contactor Switch

An overspeed contactor is actuated by high engine speed. It protects the engine from damage due to overspeeding. The overspeed switch is mounted on the tachometer drive. If the engine overspeeds, the switch contacts close and signal the shutoff solenoid 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).

OVERSPEED CONTACTOR
1. Reset button.

Pressure Switch

A 5L5500 Pressure Switch, in some automatic start-stop systems, is in the circuit to keep the rack solenoid from staying energized after shutdown. The switch opens the circuit when fuel pressure falls after the engine has stopped.

A second similar pressure switch is in the battery charging circuit to open the circuit between the alternator regulator and charging alternator when pressure lowers after the engine has stopped.

PRESSURE SWITCH

On electric governor equipped automatic start-stop applications, a similar switch opens to allow the electric governor to control engine speed when adequate oil pressure is reached.

Oil Pressure And Water Temperature Shut-Off - System Operation

D346 and D348 Engines

Engine oil under pressure enters line (1) from the auxiliary oil manifold (2) and flows behind the control piston in the oil pressure and overspeed shut-off control (3). When a water temperature shut-off control valve is used, a line (5), connected to the oil pressure and overspeed shut-off, supplies pressure oil to the valve (6). When engine coolant temperature is normal, valve (6) remains closed and no oil can flow through the valve and into the dump line (4).

Should the coolant temperature become excessive, the thermostatically controlled valve opens and oil flows through the dump line and into the engine crankcase. Thus, a low oil pressure condition is actually simulated and the oil pressure shut-off control then stops the engine.

After a shut down caused by excessively high water temperatures, depress reset button and reset the release rod.

D346 AND D348 OIL FLOW-SCHEMATIC
1. Oil inlet line. 2. Auxiliary oil manifold.^* 3. Safety shut-off control. 4. Dump line. 5. Oil line. 6. Water temperature shutoff control valve.

^*On later engines the oil inlet line connects to the junction block welded to the aftercooler.

D343 Engines

This oil pressure shutoff is mounted on the hydra-mechanical governor cover. The spring (2) is compressed, when starting the engine, by moving lever (1) against spring pressure. As oil pressure increases, it moves piston (3) to hold spring (2) compressed. Thus full movement of the rack can be controlled by the governor while the engine runs with adequate oil pressure.

As oil pressure falls below 8 psi (0,56 kg/cm²), the force of spring (2) moves piston (3) to contact the shutoff lever (5) and moves the rack to shutoff position.

Any oil exhausted through passages (4) in piston (3) drains from the governor cover through tube (6) to the crankcase.

The use of a water temperature control valve (7) connected with the oil supply tube will simulate oil pressure failure, thus affecting shut down of the engine.

D343 OIL PRESSURE SHUT-OFF (Typical Illustration)
1. Control lever. 2. Spring. 3. Piston. 4. Oil passage. 5. Shut-off lever. 6. Tube. 7. Water temperature shut-off control valve.

Water Temperature Shut-off Control Valve Operation

The water temperature shut-off in itself is a control valve for the oil pressure shut-off. It is actually the oil pressure shut-off that functions to stop the engine.

WATER TEMPERATURE SHUT-OFF CONTROL VALVE
1. Spring. 2. Inlet port. 3. Stem. 4. Thermostat assembly. 5. Ball. 6. Outlet port.

Thermostat assembly (4) is immersed in engine coolant. When the water temperature is normal, spring (1) holds ball (5) on its seat which blocks the oil flow. This allows oil pressure to build up in the safety shut-off system. Abnormally high engine water temperature causes the thermostat assembly to expand against the stem (3) which unseats the ball (5). This allows oil held under pressure in the safety shut-off control system to return to the engine crankcase through the outlet port (6). The resultant drop in pressure causes the oil pressure shut-off to shut down the engine.

Oil Pressure Contactor Switch

An oil pressure contactor protects the engine from damage due to low oil pressure. When oil pressure drops below the established limits, one set of contacts close thus signaling the shutoff solenoid to shut down the engine. On automatic start-stop applications a second set of contacts open to disconnect starter solenoid, when engine is running with normal oil pressure.

The oil pressure contactor switch can be wired into an alarm system or light to signal low oil pressure.

Micro Switch Type

As pressure in bellows (6) increases, arm (4) is moved against tension of spring (3). When projection (10) of arm (4) touches arm (9), pressure in the bellows moves both arms and in turn moves micro switch button (8) to activate the switch contacts.

Where the switch is equipped with a set-for-start button, manual control of the switch contacts is accomplished by pusing in the button. Latch plate (7) holds arm (9) against micro switch button (8). When pressure moves arm (4) so arm contacts latch plate (7), the set-for-start button is released and returned to the out position by spring (5).

OIL PRESSURE CONTACTOR (Micro Switch Type)
1. Lock nut. 2. Adjusting screw. 3. Spring. 4. Arm. 5. Spring. 6. Bellows. 7. Latch plate. 8. Micro Switch button. 9. Arm. 10. Arm projection.

Earlier Type Switch

Oil pressure contactor switch with control knob (1) must be reset every time the engine is stopped. Turn the knob (1) counterclockwise to the OFF position. The knob moves to the RUN position when normal oil pressure is sensed.

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

Wiring Diagram For Alarm System

HIGH WATER TEMPERATURE AND LOW OIL PRESSURE ALARM SYSTEM
1. Water temperature contactor. 2. Oil pressure switch (normally closed). 3. Battery. 4. Toggle switch. 5. Signal light. 6. Horn.