The Vandervell Dual-Ignition System.
Page 17
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One of the most-interesting systems of dual ignition which has been brought to our notice, during recent months, is that introduced by Messrs. C. A. Vandervell and Co., of Warple Way, Acton Vale, London, W. In this system, many of the objections inherent to certain " self-starting " dual magnetos have been overcome. Ohio. amongst such troubles, probably, is that, when the circuit is closed through the starting switch; the hightension spark is prone to jump from the high-tension brush to the nearest distributor segment, unless, by a lucky chance, the engine should have stopped in such a position that the brush is in electrical contact with one of the segments. The extreme width which must be given to the segments, on most magneto distributors, in order that the ignition may be equally disc-. tire when supplied from a battery and coil as when derived from the magneto windings, is largely responsible for the tendency to jump across the insulating spaces between adjacent segments ; increased width of segments can only he obtained at the cost of decreased widths of insulating spaces. In order, therefore, to overcome this difficulty, i he Vandervell firm has arranged that the plate which carries the segments of the high-tension distributor may be rocked about the centre of rotation of the arm that carries the carbon brush. the movement, of course, being in unison with that of the low-tension contact-breaker sleeve. This inter-connection, of the high-tension distributor and the low-tension contact breaker. ensures that—with the, widest possible range of advance and retard—the
high-tension brush always makes contact with one of the distributor segments at the preeise instant of the passing of the high-tension current.
The armature is one of the doublywound type, with the condenser assembled on the same spindle; the complete unit is mounted on substantial ball bearings. The low-tension contact breaker is fitted within a case, at one end of the armature spindle, and the actual contact with the two fixed segments in the cover of the case is made by a carbon brush that is carried on the rotating contact-breaker arm. This carbon brush and those employed in the high-tension circuit are provided with wires, which permanently connect. the brushes to their respective sockets they do not, there fore, rely, for electrical connection., on frictional contact with the sockets. Another point which is well worth noting is that no two connections, either on the magneto or the coil— which latter, with a battery, completes the outfit—are interchangeable: the terminals all differ, either in respect of diameter or shape, so that even the most-careless driver or mechanic could not wrongly connect up the magneto, coil and battery after they have once been correctly wired. Tile standard coil, together with a switch, is made up as one compact and sturdy unit, which is enclosed within a dust-proof case. The maker claims that the coil may he worked for very long periods, without showing any tendency for the windings to become overheated.
This Vandervell outfit may well be classed as a true dual system, as distinct from a " self-starting" arrangement only. The magneto is an entirely-independent and self-contained high-tension machine, the distributing mechanism of which, however, is also employed in connection with the battery and high-tension mil. Each part has been designed with a view to ease of adjustment.