THE MAGNETO SWITCH

Evening Post, Volume CX, Issue 83, 4 October 1930, Page 24

THE MAGNETO SWITCH

TRACING VARIOUS FAULTS

Not every car owner knows that to switch off the magneto the switch has to be closed, which is just the reverse of an ordinary switch operation. What the .switch does is to "earth" or, more correctly, connect to frame' the prini; ary winding of the magneto armature. Unless this connection is perfect very puzzling symptoms may arise. The engine may continue to run spasmodically or the switch may have no enxci. It is not so easy to make a perfect "earth" as completely to break a circuit, consequently i£ there is an imperfect connection when the switch is closed the magneto will continue to spark even though weaker than normal. If a switch fault is suspected, first examine the spring in the cover of the contact breaker. It is iutended to make good contact with the head of tho «entral bolt in the contact breaker. In some cases there is a carbon button pressing on the bolt head. It is important that the spring has sufficient tension to ensure good contact. The fault may be in the wire from the magneto terminal to the switch. Supposing the engine continues to run when switched off, connect a piece of wire to the switch terminal on the magneto and with the other end scraped clean firmly touch any part of the engine that presents a clean metallic. surface. If the engine stops, ifc proves that there is a fault either in the switch wire or in the switch. Cases have occurred of the wire breaking under the insulation and thus remaining unsuspeete'd. The end of the wire connecting to the switch may be loose or even disconnected from the terminal. Some switches become defective owing to wear of the contact surfaces. This fault can be detected by pressing the contact surfaces firmly together when the engine in continuing to run switched off1. The application of pressure will probably cause it to stop, proving that there is a bad contact. Another possibility is that the switch itself does not make a good "earth," therefore .the terminal lead should be examined. This applies more to the older form of separate ignition switch and not to the type in which it is included in a switch panel. "■