]
Preservation of Track.--All the wooden parts of an outdoor track should
be well creosoted before use.
The Electric Locomotive.
An elevation and a plan of this are given in Fig. 47. The two pairs of
wheels are set close together, so that they may pass easily round curves.
[Illustration: Fig. 47.--Plan and elevation of electric locomotive.]
The Motor.--A motor of ordinary type, with electro field magnets, is
unsuitable for traction, as it cannot be reversed by changing the direction
of the current, unless a special and rather expensive type of automatic
switch be used. While a motor of this kind is, in conjunction with such a
switch, the most efficient, the motor with permanent field magnets is
preferable as regards cost and ease of fixing. It can be reversed through
the rails. The armature or revolving part must be tripolar to be
self-starting in all positions.
A motor of sufficient power can be bought for half a crown or less--in any
case more cheaply than it can be made by the average amateur.
The motor used for the locomotive illustrated was taken to pieces, and the
magnet M screwed to a strip of wood 1-5/8 inches wide; and for the original
armature bearings were substituted a couple of pieces of brass strip, HH,
screwed to two wooden supports, SS, on the base, E (Fig.
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