2.3.
WHAT A TURNOUT IS
Turnouts make it possible for a train to leave one track and enter another. Without them, yards, sidings,
and passing tracks would be impossible. Most operating employees refer to turnouts as "switches," but
technically a switch is only one part of a turnout. To distinguish between the two terms in this text, the term
switch is used only to refer to the pair of movable rails and the necessary connections that are used to divert a
train to another track. The components of a turnout are described in subparagraph a and illustrated in figure 2.1;
its classification is discussed in subparagraph b.
Figure 2.1. Turnout Components.
a. Components. Essentially, a turnout is a combination of five components: a switch, a frog, a pair of
guard rails, closure rails, and switch ties. The switch with its controlling mechanism determines the path that
moving engines and cars take. The frog provides the means for the wheel flanges to cross the obstructing rail of
the alternate path. The guard rails, set opposite the frog point, hold the flanges of the wheels away from it to
prevent batter and taking of the wrong route. The closure rails connect the switch and the frog. Switch ties, of a
predetermined length for each gage and frog number, extend under both tracks, well beyond the frog. Frog
number is discussed in subparagraph b.
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