The other terminal G, of the secondary coil, also extends to the spark plug F, there being, of course, a gap between the two ends of these wires in the spark plug.
Now, close up to the secondary, D, is a condenser H, the terminals of which are connected up with the two wires E G, and between the condenser and the spark plug F, is the interrupter I.
The High Tension Connections.—With this understanding of the action of the magneto, the accompanying sketch of a high tension system will be understood.
The magneto A, Fig. 91, has on its armature shaft B, two distributer rings C D, which form the terminals for the two wires E F, which run out from the armature winding. C is connected by metallic contact with this shaft, and D insulated therefrom. Also, alongside of the ring D, is the interrupter wheel G which engages the finger H, and thus interrupts the circuit.
Above the armature shaft, and parallel therewith, is a shaft I, turned at half the armature shaft by means of the two gear wheels J K. On the end of this shaft is a finger J, revoluble therewith, and this engages successively with four contact plates K, each plate being connected with a spark plug in the engine, assuming, of course, that there are four cylinders in the engine.
Fig. 91. High Tension Connections.
The ring C has its contact finger connected by a wire L with one end of a primary coil M, while the other terminal has a wire N which goes to one terminal of the interrupter G. The other outlet of the interrupter is connected up with the contact finger of the other collector ring D. This contact finger also has a wire connection P with one terminal of a condenser Q, the other end of the condenser being connected with the wire N, running from the primary coil M.
The Secondary Coil.—The secondary, or high tension coil R, has one end grounded, which means that it is connected up with the metal of the engine, and the other terminal is connected by a wire T, with the finger J on the distributer disk.
In operation, we will assume that the current leaves the armature over the wire E; it has two paths, one through ring D, wire O, and interrupter G, back to the other wire F of the armature; or, after passing the ring D it may pass over O, to the interrupter, then through wire N, primary coil M, and wire L, back to the armature.