The ABCs of the Shower of Sparks
Contents
1. Part Number Description 10 357200 1 Key Twist Start 10 357210 1 Key Push Start 10 357230 1 Lever Twist Start 10 357240 1 Lever Push Start 10 357250 1 Lever Twist to Start Push to Prime 10 357290 1 Key No Start 10 400185 1 Lever No Start Starting Vibrators Used with Ignition Part Number Description System 10 176487 121 12VDC S 200 10 357487 241 24VDC S 200 10 176487 122 12VDC S 1200 10 357487 242 24VDC S 1200 10 382775 12 12VDC D 2200 D 3200 10 382808 24 24VDC D 2200 D 3200 10 400608 121 12VDC W Relay S 200 10 400608 241 24VDC W Relay S 200 10 400608 122 12VDC W Relay S 1200 10 400608 242 24VDC W Relay S 1200 10 400608 123 12VDC W Relay D 2200 D 3200 10 400608 243 24VDC W Relay D 2200 D 3200 NOTE Not a comprehensive parts list Consult airframe manufacturer s parts catalog for ignition switch and starting vibrator application 1 When using other than combined Continental Motors ignition and starting switches use starting vibrator with relay Consult airframe parts catalog for ignition switch and starting vibrator application ABCs of the Shower of Sparks 31 August 20112. getting good contact Look at the contact springs in the magneto with a flashlight dirty or burned contacts may be the cause ABCs of the Shower of Sparks 13 31 August 2011 H Airframe Circuits Variations The circuit depicted below is common but variations exist On some dual engine airframes the IN terminal of the vibrator connects directly to the battery bus usually through a circuit breaker to allow the same vibrator to serve both engines with the advantage of providing full battery power to the vibrator without the increased resistance of complex wiring circuits TO START L SOLENOID FROM BATTERY Some switches feature a spring loaded start function while others are designed with a PUSH TO START feature Many combinations are available limited only by the demand for possible start and run combinations Some switches feature a spring loaded start function while others are designed with a PUSH TO START feature Many combinations are available limited only by the demand for possible start and run combinations ABCs of the Shower of Sparks 31 August 2011 R L Bon START SWITCH ROTARY SWITCH TWIST TO START ABCs of the Shower of Sparks 31 August 2011 5 Ke L Bon START SWITCH ROTARY SWITCH PUSH TO START R L Bop ROTARY SWITCH PUSH TO PRIME l Ignition Switch and Starting Vibrator Reference Ignition and Starting Switches
3. the engine not running and all switches in the OFF position As the illustration points out each magneto SWITCH input is connected to ground through the ignition switch LEFT MAGNETO START SWITCH RIGHT MAGNETO BATTERY TO START SOLENOID Figure 1 Magneto Circuit OFF 8 ABCs of the Shower of Sparks 31 August 2011 2 Turn the ignition switch to the START Figure 2 position Lines in the illustrations indicate the circuit path a The starter solenoid energizes engages the starter and turns the crankshaft b Vibrator pulses flow to both contacts in the L magneto but are shorted to ground c The R magneto is grounded through the ignition switch LEFT MAGNETO VIBRATOR o BATTERY TO START SOLENOID Figure 2 Vibrator Energized ABCs of the Shower of Sparks 31 August 2011 3 When the crankshaft reaches the full advance Figure 3 firing position the advance contacts in the L magneto open but the closed retard contacts short the vibrator current to ground The R magneto is grounded through the ignition switch so no spark reaches either spark plug LEFT MAGNETO START SWITCH IRIGHT MAGNETO BATTERY TO START SOLENOID Figure 3 Advance Contacts Open 10 ABCs of the Shower of Sparks 31 August 2011 4 When the crankshaft reaches the piston TOP CENTER position in Figure 4 the retard contacts open and remove the ground from both con
4. until it contacts the nail head COIL In the ignition lA system we build up current in the coil and then stop it by opening a set of BREAKER CONDENSER breaker points In an automobile POINTS current is provided by the battery In a magneto the current is developed in the coil by a rotating magnet The principle is the same in either case A good analogy of this principle is the action of a heavy piston in a cylinder filled with hydraulic fluid HEAVY PISTON VALVE OPEN COIL ay DIAPHRAGM BREAKER POINTS Start the heavy piston down the cylinder and slam the valve shut The piston wants to keep moving and the pressure built up would burst the valve if the fluid did not have another path to travel into the box containing the rubber diaphragm The momentum of the piston is converted into a force which bends the diaphragm upward CONDENSER CHARGES WHEN POINTS OPEN ABCs of the Shower of Sparks 3 31 August 2011 In the ignition system we use this same principle to generate a surge or kick of electrical force current across the coil The current in the coil wants to keep flowing so it builds up voltage across the ends of the coil If not for the condenser the voltage could burn the breaker points when they open The built up voltage surge can be amplified by adding a transformer to the circuit On Continental Motors magnetos the voltage is amplified in the magneto and distributed as hig
5. CONTINENTAL IGNITION SYSTEMS NDA Printing Instructions To print this document in its intended booklet format 1 From the File menu select Print Printer Name MES CLE z Properties Status Ready Comments and Forms Type HP LaserJet 2430 PCL 6 Document Print Range Preview Composite all C Current view Current page Cpaesfi 20 subset Allpagesinrange Z J Reverse pages p Page Handling Copies 1 V call Page Scaling Booklet Printing bd Booklet subset Both sides X Sheets from 1 to 5 I Auto Rotate Pages Binding Left Ei Units Inche T Print to file nits Inches T Print color as black 11001 C Printing Tes Advanced Summarize Comments Cancel Select the Printer Name to send the output to from the available options If the printer automatically prints duplex both sides of the paper select that option from the printer Properties dialog box Click All option in the Print Range group In the Page Handling group select the number of copies to print Change Page Scaling to Booklet Printing and Booklet subset to Both sides with Binding on the Left side Click the OK button at the bottom right to commence printing lt Continental Motors Inc Publication IGN 52 9011 CONTINENTAL MOTORS INC AUGUST 2011 Supersedure Notice This manual is a revision of the information contained in Publication Part No IGN 52 dated 15 December 2009 Previous edit
6. ITCH Continental Motors S 200 S 1200 and D 3200 series ignition systems B About Impulse Couplings Impulse couplings have been used for many years on internal combustion engines The purpose of the impulse coupling is 1 To SNAP the magneto through its firing position at a faster than normal rate of speed to produce a strong spark even at slower engine cranking speeds 2 To postpone or delay the SNAP until the piston nears top center in the cylinder so ignition is retarded or delayed to prevent a kickback When the engine starts the impulse feature disengages and the impulse coupling functions as a plain drive member as long as the engine is running Impulse coupling flyweights may become magnetized which prevents the stop pins from engaging properly When this occurs the impulse coupling must be serviced degaussed Cold weather may also prevent the impulse couplings from engaging when congealed oil dampens the flyweight s snap function 2 ABCs of the Shower of Sparks 31 August 2011 Impulse couplings produce only one spark for each cylinder firing cycle Under certain starting conditions a Shower of Sparks ignition may be more desirable C The Most Mysterious Part of an Airplane The high voltage spark in a magneto ignition system is produced by applying the same principle that makes a half pound hammer strike a nail with a 200 Ib force Momentum builds through the swing of the hammer
7. ally grounded to prevent possible advance ignition and engine kick back RIGHT MAG BOOS To get a retarded or late spark for starting the LEFT magneto is assembled with two contact assemblies in it The ADVANCE or MAIN contacts are synchronized to the crankshaft timing mark before piston top dead center The RETARD or START contacts open a few degrees after the ADVANCE or MAIN contacts open depending on engine requirements LEFT MAGNETO EE see Ss Se Orne Ae Yo O main N 7 RETARD CONTACTS CONTACTS NOTE MAIN AND RETARD BREAKERS MAY BE REVERSED DUE TO MAGNETO ROTATION The ignition switch connects the retard contacts and the main contacts together during starting As long as either contact is closed the magneto coil will be short circuited to ground and cannot produce ignition voltage Thus the vibrator cannot produce a spark until the retard contacts open ABCs of the Shower of Sparks 31 August 2011 When the engine starts the spring loaded ignition switch is released to the BOTH position This disconnects the retard contacts vibrator and starter from the circuit and removes the ground from the RIGHT magneto ADVANCE BATTERY PART OF IGN SW RET L VIBRATOR MAG BKR coL z CLOSED ABCs of the Shower of Sparks 7 31 August 2011 F Circuit Analysis 1 Figure 1 represents a magneto circuit with
8. e good clean connections through the circuit current may not reach the magneto Listen to the vibrator buzz while cranking the engine The tone should change as the magneto breaker points open and close If no buzzing is heard check the voltage at the IN terminal of the vibrator while cranking Minimum voltage must be at least 8V on 12V systems or 13V on 24 V systems If the tone doesn t change check the magneto wiring and the contact springs in the magneto breaker cover More on Troubleshooting If the RETARD contacts don t open you ll get no spark and no start If the RETARD contacts don t close you ll be cranking with a fully advanced boosted spark and may experience kick back this may also result if the RETARD contacts wiring is broken or RETARD circuit connections are loose or damaged If the RETARD contacts open too late the engine may fire but not develop the momentum to run Check ignition timing If the ADVANCE contact wiring is broken or circuit connections are faulty the magneto will be permanently HOT vibrator current will have no path to the magneto The tip off to this condition is the sound from the vibrator instead of changing tone the vibrator will stop and start as the engine is cranked It is a good idea to inspect both ADVANCE and RETARD magneto connections when difficulty is experienced If you can t feel the terminal compress the contact spring in the S 200 or D 3000 magneto slightly you may not be
9. eeeeeeees 4 E Circ it TREO rreh tenaa ea ore di rna e aea e 5 F Circuit Analysis eedi kta aie nea adie 8 G At the Maintenance Hangab secceesseeesneereeseeeeeneeeeeneeeeeees 13 H Airframe Circuits Variations ecceeceeeceeeneeeeeeeeeeteneeseeeeeeeeeaes 14 l Ignition Switch and Starting Vibrator Reference 16 DISCLAIMER Information contained in this document is for reference only not representative of any particular Continental Motors ignition system Consult the appropriate ignition system service manual for application specific magneto service and troubleshooting instructions ABCs of the Shower of Sparks 31 August 2011 A Introduction An early engine starting aid was the hand cranked booster magneto many folks working in the aviation industry may never have heard of one It connected to the aircraft magneto circuit during a hand prop start By turning the crank handle at the same time as the propeller a stream of high voltage was emitted into the distributor section of the magneto While BOOSTER MAGNETO the booster magneto was functional it required at least two people to start the engine Impulse couplings and vibrator type starting booster circuits replaced the function of the external booster magneto The vibrator shower of sparks starting booster circuit widely used on aircraft engines TO MAGNETO Wr i is supplied with KA amp certai n MAGNETO VIBRATOR SW
10. h voltage DISTRIBUTOR o ae o TO SPARK PLUGS ee D Engine ianaan Theory of Operation A piston engine has to RUNNING SPARK STARTING SPARK be cranked it can t start itself like an electric motor apt ae Because the starter 95 BEFORE TOP turns the crankshaft at CENTER fewer revolutions per minute RPM than normal engine ADVANCED RETARDED operation the lower RPM may not turn the magneto fast enough to generate a spark to ignite the fuel in the combustion chamber That s why impulse couplings or vibrators are used Ignition timing must be advanced to get maximum power output from a combustion engine at high RPM If we try to start the engine with advanced ignition timing combustion occurs too early and the engine kicks back and fails to start Starting ignition can be improved by retarding delaying ignition timing until the piston is close to the top of the TOP CENTER CYLINDER PRESSURE CRANKSHAFT ANGLE 4 ABCs of the Shower of Sparks 31 August 2011 cylinder on the compression stroke If ignition occurs too late the engine won t develop momentum after ignition Both starting and running spark timing has to be synchronized to the engine crankshaft piston position For best results retarded starting spark occurs when cylinder pressure is highest requiring higher voltage In cold weather the battery INDUCTION CIRCUIT engine oil and fuel are all adversely affected Engi
11. ions are obsolete upon release of this manual Effective Changes for this Manual TOE 31 August 2011 List of Effective Pages Document Title ABCs of the Shower of Sparks Publication Number IGN 52 Initial Publication Date 31 August 2011 Page Change Page Change Page Change Page Change Cover 0 Published and printed in the U S A by Continental Motors Inc Available exclusively from the publisher P O Box 90 Mobile AL 36601 Copyright 2011 Continental Motors Inc All rights reserved This material may not be reprinted republished broadcast or otherwise altered without the publisher s written permission This manual is provided without express statutory or implied war ranties The publisher will not be held liable for any damages caused by or alleged to be caused by use misuse abuse or mis interpretation of the contents Content is subject to change without notice Other products and companies mentioned herein may be trademarks of the respective owners A ABCs of the Shower of Sparks 31 August 2011 CONTENTS A Introduction 4 niche ei dsialtodahi aia aiaintaietans 2 B About Impulse CouplingS c cceeceeceeeeeeeeeseeeeeeeeseeeeneeeneeeeaeen 2 C The Most Mysterious Part of an Airplane eceeeeeeeeeereeeeeees 3 D Engine Ignition Theory of Operation cccecceeseeeeeeeeee
12. ne friction increases fuel is more II BATTERY difficult to ignite and the battery a has less power right when it needs the most Under these conditions a single one shot type of spark delivered by an impulse coupling magneto may VIBRATOR AGNETO not be enough to ignite a lean COIL fuel mixture in a cold cylinder By starting at top center and throwing a continuous stream or shower of sparks across the spark plug we increase the likelinood of igniting the fuel mixture in the cylinder The induction vibrator does exactly this It is a special form of buzzer which provides about 200 sparking pulses per second E Circuit Theory PLUG FIRES FROM HERE To keep it simple here s how the vibrator does its job Current flows from the battery to the vibrator coil and contacts and on to the magneto coil completing its return circuit through the engine and airplane ground MAGNETO COIL VIBRATOR This does two things e sets up a current in the magneto coil e magnetizes the core of the vibrator coil which pulls the vibrator contacts apart ABCs of the Shower of Sparks 5 31 August 2011 When the vibrator contacts break the circuit the current is brought to a sudden stop producing the required voltage surge in the magneto coil for ignition purposes The condenser prevents excessive arcing of the vibrator contacts In most systems only one magneto is boosted for starting The second magneto is automatic
13. tacts Vibrator pulses pass thorough the primary winding of the L magneto and induce high voltage in the secondary winding The high voltage transmits through the distributor to the spark plug The left magneto will continue to supply retard spark as long as the switch remains in the START position RIGHT MAGNETO VIBRATOR BO BATTERY TO START SOLENOID Figure 4 Both Contacts Open ABCs of the Shower of Sparks 11 31 August 2011 5 Release the ignition switch to the BOTH position Figure 5 and the circuit changes to normal operation a Magnetos fire at specified ignition position b The vibrator and starter are disconnected c Both spark plugs fire during ignition START SWITCH RIGHT MAGNETO VIBRATOR BO BATTERY TO START SOLENOID Figure 5 Normal Operation 12 ABCs of the Shower of Sparks 31 August 2011 G At the Maintenance Hangar General Troubleshooting If you have an engine ignition problem remember the vibrator can t do its job unless 1 It has enough input voltage 2 The retard and advance contacts are BOTH correctly timed 3 The magnetos are correctly timed to the engine 4 The vibrator is correctly adjusted internally Refer to the airframe maintenance manual trace the circuit feeding the vibrator battery current Several components such as circuit breakers switches and intermediate connections etc could reduce the input voltage Unless you hav
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