Woodward PSG Governor
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.
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. Lever. 11. 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 drive 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 by 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 (24) fits into the cylinder bore and is connected to the actuating lever by shaft (20), link (21) and lever (22).
GOVERNOR SERVO MECHANISM
20. Shaft. 21. Link. 22. Lever. 23. Shaft. 24. Piston. 25. Cam.
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.
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.
AIR STARTING SYSTEM
1. Balanced whistle valve. 2. Oiler. 3. Air motor.
The air starting system is mounted on the right side of the engine. 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)
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 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.
AUTOMATIC START-STOP SYSTEM COMPONENT LOCATION DIAGRAM
This describes a typical application of the automatic start-stop system for diesel engines.
NOTE: The natural gas engine automatic start-stop system operates similarly. The difference is that engine shutdown is accomplished by, grounding the ignition system and, a solenoid operated valve closing in the fuel supply line.
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.
The automatic start-stop system contains three main wiring circuits:
- Commercial power source.Electric set or power unit.Cranking panel, starting motor and battery.
The three circuits terminate at the automatic transfer switch. This is a throw-over switch between the load and the electrical power source.
A commercial power activated relay in the transfer switch 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.
Equipment on engines equipped with the start-stop system includes:
- FPS. Fuel Pressure Switch (most models)WT. Water Temperature Contactor SwitchOPS. Oil Pressure Contactor SwitchSM. Starting MotorMS. Magnetic SwitchOS. Overspeed Contactor SwitchTSI. Terminal StripRS. Shutoff Rack Solenoid
Each of the engine mounted shutoff components are explained and illustrated in separate topics.
AUTOMATIC START-STOP CRANKING PANEL
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 lamp 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:
- RR. Run RelayAR. Auxiliary RelaySR. Shutdown RelayIR. Initiating RelayOCT. Overcrank TimerSW-2. On-Off-Stop SwitchSW-1. Manual-Automatic SwitchD. Diode
The following description of operation refers to illustrations for the D330C and D333C Engines. These illustrations are intended as schematic representations of the operation of the standard cranking panel equipped with RR relay. They are NOT intended to be used as complete wiring diagrams.
D330C AND D333C ENGINE CONTROL PANEL SET FOR AUTOMATIC START-STOP CONTROL (SWITCH SW-2 AT "ON" AND SWITCH SW-1 AT "AUTOMATIC")
Control Panel Equipped with Run Relay (RR)
D334 ENGINE CONTROL PANEL SET FOR AUTOMATIC START-STOP CONTROL
Control Panel Not Equipped with Run Relay (RR) and Engine Not Equipped with Fuel Pressure Switch (FPS)
G333 ENGINE CONTROL PANEL SET FOR AUTOMATIC START-STOP CONTROL
Control Panel Not Equipped with Run Relay (RR) and Engine Not Equipped with Fuel Pressure Switch (FPS)
Automatic Cranking Operations
1. When engine is required to start, 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, and at same time overcrank timer is energized and begins to run.
CONTROL PANEL SATISFYING AUTOMATIC OPERATION DEMAND CRANKING (SWITCH SW-2 "ON," SWITCH SW-1 AT "AUTOMATIC")
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 AFTER START (OIL PRESSURE CONTACTOR DIRECTED)
3. If engine does not start in 30 seconds, overcrank timer contacts close energizing shutdown relay and lighting alarm lamp. Operation of shutdown relay interrupts current flow of initiating relay which opens and stops cranking action. Shutdown relay remains energized until switch SW-2 is manually turned to "OFF" position.
NOTE: Standard panel provides a single cranking cycle of 30 seconds duration.
CONTROL PANEL STOPPING CRANKING WHEN ENGINE DOES NOT START (OVERCRANKING TIMER DIRECTED)
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 rack solenoid which closes engine fuel rack. A parallel 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 (ENGINE MOUNTED TROUBLE SENDING UNITS DIRECTED)
2. 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.
CONTROL PANEL CALLING FOR ENGINE SHUTDOWN (EMERGENCY POWER NOT REQUIRED: INITIATING CONTACTORS DIRECTED)
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.
CONTROL PANEL MANUAL STARTING OPERATION (SW-2 AT "ON," SW-1 AT "MANUAL")
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.
CONTROL PANEL EMERGENCY STOP FUNCTION (SW-2 OPERATED TO "STOP" POSITION, SW-1 AT ANY POSITION)
Attachments For Control Panel
CONTROL PANEL OPTIONAL (A separate lamp for each type of shutdown).
With this attachment the reason for a safety shutdown is readily apparent through lighting of a particular indicator lamp.
Cycle Cranking Timer
A diaphragm return solenoid and an air bleed through the spring-loaded diaphragm provides five, ten second cranking cycles with a ten second delay between cranks. The standard cranking panel provides only a single cranking cycle of 30 seconds duration.
Time Delay Relay
This relay permits the engine to run for two minutes after the load is removed, and allows for slower cooling. The relay also prevents the cranking panel from being thrown out of circuit if it receives a start signal while it is shutting down. This condition might occur when commercial power fluctuates every few seconds. The standard cranking panel shuts engine down immediately when load is removed.
AUTOMATIC START-STOP ENGINE MOUNTED CONTROLS (Earlier Control for D330 and D333 Engines)
(On D334 Engines there is no fuel pressure contactor. On G333 Engines the magneto replaces the fuel pressure contactor and the TS-1 connection is removed from terminal strip. The magneto should be grounded. Governor synchronizing motor connects to 12, 13 and 14 on the terminal strip.)
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 need identifying with continuity tester or by observation to be sure of proper connection.
AUTOMATIC START-STOP ENGINE MOUNTED CONTROLS (Later Control for D330 and D333 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. Fuel pressure contactor. 10. Terminal strip. 11. Governor synchronizing motor.
IGNITION DISTRIBUTION SYSTEM DIAGRAM (Equipped with Solid State Magnetos)
WIRING DIAGRAM WITH OVERSPEED CONTACTOR AND REMOTE MOUNTED GAS VALVE
In the event of normal stopping, engine overspeed, high water temperature or low oil pressure, the instrument panel magnetic switch is energized and interrupts the mmagneto output and activates the gas valve solenoid to stop the engine by grounding the magneto and closing the gas supply valve. On solid state systems a different magnetic switch is required to carry the higher output of the magneto.
WOODWARD SYNCHRONIZING MOTOR DIAGRAM
1. Single pole double throw switch. 2. Red wire connects 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 connects to switch terminal marked "L" for UG8 Governors or to "R" for PSG Governors.
Water Temperature Contactor Switch
A water temperature sending unit is located in the water temperature regulator housing. The unit is nonadjustable. Thermal expansion of the element operates a micro-switch that signals the shutoff solenoid which causes engine shutdown. If overheating occurs due to low coolant level or no coolant, the sending unit will not function. The water temperature element must be in contact with the coolant.
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
The rack shutoff solenoid, when energized, moves the shutoff lever in the governor housing which in turn moves the 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.
Overspeed Contactor Switch
An overspeed contactor, which is actuated by high engine speed, 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 SWITCH
1. Reset button.
A fuel pressure switch, in 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. This switch is located at the fuel filter.
A second similar pressure switch is in the battery charging circuit to open the circuit between the alternator regulator and charging alternator when oil pressure lowers after the engine has stopped. This switch is located on the left side of the engine near the flywheel housing.
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. A second set of contacts, on automatic start-stop applications, opens to disconnect the starter solenoid or magnetic switch when engine is running with normal oil pressure.
The oil pressure contactor switch can also 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 pushing in the button.
OIL PRESSURE CONTACTOR (Micro Switch Type)
1. Locknut. 2. Adjusting screw. 3. Spring. 4. Arm. 5. Spring. 6. Bellows. 7. Latch plate. 8. Micro Switch button. 9. Arm. 10. Arm projection.
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).
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.
Oil Pressure-Water Temperature Shutoff
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 will 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 oil from the governor cover through tube (6) to the crankcase.
The use of a water temperature valve (7) connected with the oil supply tube will simulate oil pressure failure, thus affecting shut down of the engine.
OIL PRESSURE SHUT-OFF
1. Control lever. 2. Spring. 3. Piston. 4. Oil passage. 5. Shutoff lever. 6. Tube. 7. Water temperature shutoff valve.
Gas Shutoff Valve
It is necessary to push the reset button to start the engine. When the engine is stopped, a solenoid on the gas valve is activated by the magnetic switch. The solenoid then closes the gas valve and connects the magneto to ground. The solid state ignition system requires a different gas line valve than the standard spark gap magneto system.
WIRING DIAGRAM WITH OVERSPEED CONTACTOR AND REMOTE MOUNTED GAS VALVE
The circuit breaker in the later automatic start-stop starting system is a safety switch that opens the battery circuit whenever the current in the starting system is higher than the rating of the circuit breaker.
A metal disc with a contact point completes the electric circuit through the circuit breaker. High current in the electric cranking system will cause heat in the metal disc. Heat will cause distortion of the disc, causing the contacts to open. An open circuit breaker will reset automatically after it cools.
CIRCUIT BREAKER SCHEMATIC
1. Disc in open position. 2. Contacts. 3. Disc. 4. Battery circuit terminals.
Solid State Ignition
SOLID STATE IGNITION SYSTEM
1. Transformer. 2. Wiring harness. 3. Spark plug cover. 4. Solid state magneto. 5. Timing bolt.
The solid state ignition system consists of five basic components: a solid state magneto, ignition transformers for each cylinder, wiring harness, spark plugs and engine instrument panel. The transformers, wiring harness and spark plugs are covered in basic engine information.
The instrument panel contains a magnetic switch, manual stop switch (1), oil pressure gauge (2), and a water temperature gauge (5) which are connected to the magneto.
In the event of normal stopping, high water temperature or low oil pressure, the magnetic switch is energized and interrupts the magneto output, this stopping the engine. On solid state systems a different magnetic switch is required to carry the higher output of the magneto.
1. Stop switch. 2. Oil pressure gauge. 3. Magnetic switch reset button. 4. Oil pressure gauge reset button. 5. Water temperature gauge.
Before cranking a cold engine, the magnetic switch and oil pressure gauge reset buttons (3) and (4) should be pushed in. This overrides grounding the magneto as is usual in the case of low oil pressure. Normal oil pressure releases the lock out and the gauge switch is ready to signal a shut down in case of low oil pressure.
When the water temperature gauge switch is operating properly, a hot engine cannot be started until the engine has cooled. Holding in the magnetic switch reset button will override the oil pressure and water temperature gauge switches.
The solid state magneto is a self-contained electric generating unit. Current is produced in the alternator section of the magneto (right hand side). Current is stored in the capacitor and released, then distributed through the circuit board in the pulser distributor section (left hand side). This system uses capacitive storage and low tension distribution.
Two moving parts, the magnet rotor and pulser rotor shaft both rotating on ball bearings will give long service life. Engine timing will remain as set, because no mechanical rubbing or wearing parts exist that cause gradual timing changes.
CUTAWAY VIEW OF SOLID STATE MAGNETO
The solid state magneto utilizes non-wearing electronic switching to handle high surge currents and insures ignition at the highest of combustion chamber pressures. With solid state ignition, energy storage and voltage stepup are accomplished separately by the use of electronic switching. This system eliminates breaker points, contactors, and brushes. There is no arcing and only minimum wear. An electromagnetic spark advance is used. An ignition spark of high intensity is produced to fire the air-fuel charge under all operating conditions.
The alternator creates a voltage as the magnet rotor is driven by the engine through a drive coupling. The alternating current is rectified and stored in a capacitor (4). A zener diode, on the power board, regulates the capacitor voltage level for proper firing. As the pulser rotor (8) passes each pulser coil (trigger circuit) (7), a triggering voltage is produced and sent to the electronic switch (silicon-controlled rectifier) (9) for the firing cylinder. The switch is then 'turned on' and allows the capacitor (4) to discharge, through the distribution board (5), the low voltage high current impulse to the ignition transformer. In turn, the transformer produces a high voltage low current impulse which is sent across the spark plug electrodes. This same process recurs as the pulser rotor passes each pulser coil.