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desired to interrupt the magneto action and the switch is opened when the magneto is to supply current.
The internal wiring is not difficult to follow. One end of the primary winding is attached to the condenser case while the other is joined to the ground. The same wire that joins the condenser to the primary coil is attached to one of the leads of the secondary winding. The other end of the secondary winding goes to the col
lector ring carried by the insulating spool on the magneto armature shaft and from thence the current is collected by a carbon brush and delivered to the revolving portion of the secondary distributor. The primary wire attached to the condenser case extends through and is in electrical connection with the insulated contact point in the contact breaker. The other contact lever is grounded. The condenser casing is made in two parts, one of these being in metallic contact with the ground while the other which is insulated from it serves to convey the primary current to the breaker box.
As the armature revolves, the contact breaker points separate when the bell crank is rocked by the actuating cam rolls and each time that this break occurs, this being timed so that it is simultaneous with the position of maximum current generation of the armature, a spark takes place at whichever spark plug the distributor arm (which is also timed in relation to armature travel) happens to deliver the current to. As will be evident the true high tension magneto system is very simple when compared to battery and coil ignition systems that do not give as hot a spark and that are not nearly as reliable.
Q. Outline transformer coil magneto system.
A. The wiring arrangement of a transformer coil ignition system using magneto current is clearly shown at Fig. 105, the various parts being separated in order to make the action clear. As is true of the simpler high tension system the spark plugs are connected to terminals on a distributor and the high tension current is delivered to the central revolving member of the magneto distributor. Instead of the derived current being taken directly from the magneto armature it is passed through the primary winding of an induction coil which is similar in action and construction to the form used with batteries except that it has no vibrator. One end of the primary winding is grounded while the other goes to the magneto terminal of the switch and from thence through the magneto armature from which it flows back again to the ground through the medium o the magneto contact breaker.
When the armature is in the position of maximum current generation, the platinum points of the contact breaker are separated by the cam and the primary current must rush through the primary winding of the coil before it reaches the ground instead of having a short circuit to the ground through the contact points of the contact breaker, as is possible when these are together. The rush of current through the primary winding induces a secondary current
Fig. 106.-Diagram Showing Wiring of Remy Magneto System for
Two Cylinder Motor.
in the winding of fine wire having sufficient voltage to overcome the air gap between the points of the spark plug.
If the switch lever is turned from the position indicated so it is in contact with buttons No. 2 and B, the battery current from a set of dry cells is used to energize the primary winding, the contact breaker of the magneto serving to interrupt the battery current and the distributor serving the same purpose whether the primary current is derived from the magneto armature winding or from the battery. The external wiring of two systems of this kind is outlined at Figs. 106 and 107. The former is for a two cylinder engine, while that at Fig. 107 is the wiring plan of the same elements shown at Fig. 105.
Q. Is the spark coil always a separate unit?
A. The spark coil used with a magneto-transformer system is always a separate unit from the armature winding but it is sometimes incorporated as part of the magneto, being carried under the arch of the magneto as in the Connecticut device or at the rear end of the magneto as in the Pittsfield construction.
Q. Describe action of double ignition system using one set of plugs.
Sometimes when two distinct ignition means are fitted and the magneto distributor and contact breaker are the timing parts of each system it is possible to utilize but one set of spark plugs instead of the two sets which are necessary in double ignition systems of the form outlined at Fig. 100. The diagram of the wiring of a double ignition system using one set of plugs is clearly outlined at Figs. 108 and 109. The arrangement is always such that either a separate