The Dixie Magneto.
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An American Machine Incorporating Several Unusual Features.
In the Dixie magneto we have a high tension ignition machine which differs in design and construction from those to which users have 'been for some years accustomed. The most important departure, however, from what might be termed present-day usage refers to the method of generating the current. The prin ciple involved is not by any means a new one. Its application, however, is distinctive.
The Standard Type of Magneto.
Of recent years the design of high-tension ignition magnetos has become almost stereotyped. The rule has been to rotate an armature and coil between the poles of a powerful magnet. The effect of rapidly and frequently breaking the lines of magnetic force has been to induce a current in the low-tension windings of the armature.This is again intensified in the high-tension windings and delivered to the terminals through a distributor. It is, of course, well known that it is. possible to produce the same effect by entirely opposite means, that is to say, by rotating the-pole pieces of a powerful magnet, so that the field is interrupted in a similar manner by a stationary armature. The latter method was adopted on the SimmsBosch magneto many years ago. In that case, however, the windings were centrally placed.
New Application of an Old Principle.
In the Dixie machine this old principle is again revived, but an B-16
entirely new method of applying it has been evolved. By reference to our illustrations, it will be gathered that the magnets are so situated on the machine as to be at right angles to the customary position. In contact with the poles of the magnet are two rotating polar extremities carried by the one spindle, and at right angles to this rotating piece is a field structure consisting of laminated pole pieces. These are in contact with the windings of the armature, and so arranged that, as stated above, the total effect is the same as if the magnet itself were being revolved in the field of the armature. It is claimed that the great difference between the Dixie and the more general type is in the fact that these rotating poles -do not reverse their polarity at any time. Consequently, the lag due to magnetic reluctance is eliminated. It is also further stated that owing to the fact that the armature is stationary it is less likely to be depreciated during use than the usual type wherein the windings and the insulation are -.subject to the action of centrifugal force owing to the very rapid rate of revolution.
Consiructional Features.
As will be seen from our illustrations, the magnets themselves are only loosely applied to the machine. The armature is carried on the top of a casing within which the pole pieces revolve, and this casing is directly connected with the advance and retard mechanism of the magneto. When it is desired, therefore, to effect a
variation in the timing of the spark, the whole of the windings, including the laminated field, are moved simultaneously with the contact breaker, thus preserving the maximum intensity of the current, no matter whether the ignition is fully retarded, fully advanced, or intermediate between either of these two extreme positions. This is undoubtedly a commendable feature.
Detail Improvements.
Detail improvements may be noticed in the methods of attaching the distribution-gear cover, and in the application and arrangement of the contact breaker. In this case, the breaker arm and contact points are stationary ; they do not revolve with the spindle. The actual make-and-break is effected by a central cam, and as a consequence any effects of centrifugal force, tending to open the contact points when they should be closed are obviated. It is also much easier to note the condition of the platinum tips at any time.
Accessibility a Feature.
Its accessibility and ease of repair are notable. In the first place, as we ourselves have proved, it is quite an easy matter entirely to dismantle the machine with the aid of a small screw-driver. The arma ture is self-contained. It can be removed and replaced if necessary by the same means. At the same time, when complete and ready for iiositicining on the engine, the machine to all intents and purposes is water and dustproof.