It will be apparent at once that a method of increasing
the tractive power of the present steam locomotives by more than 50
per cent. without adding to their weight and without injury to the
roadbed and wheel tires, such as is caused by the sand now commonly
used, would prove of considerable value, and the same holds true with
respect to electrically propelled street cars, especially as it has
been found exceedingly difficult to secure sufficient tractive
adhesion on street railways during the winter season, as well as at
other times, on roads having grades of more than ordinary steepness.
As this, therefore, is probably the most important use for this
application of the electric current, it has been selected for
illustrating this paper.
I have here a model car and track arranged to show the equipment and
operation of the system as applied to railway motors. The current in
the present instance is one of alternating polarity which is converted
by this transformer into one having the required volume. The
electromotive force of this secondary current is somewhat higher than
is necessary. In practice it would be about half a volt. You will
notice upon a closer inspection that one of the forward driving wheels
is insulated from its axle, and the transformed current, after passing
to a regulating switch under the control of the engineer or driver,
goes to this insulated wheel, from which it enters the track rail,
then through the rear pair of driving wheels and axles to the opposite
rail, and then flows up through the forward uninsulated wheel, from
the axle of which it returns by way of a contact brush to the opposite
terminal of the secondary coil of the transformer.
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