Section V. Special Switches and Track Constructions
2.29.
GENERAL
Switches without frogs, frogs without switches, and stock rails that go nowhere--all of these and more,
more switches, that is, constitute most of the subject matter of section V. This section shows how the now-
familiar switches and frogs have been adapted to suit special purposes. It tells more about stub switches and
introduces spring switches, derails, crossings, and slip switches. Also, this section discusses gantlet tracks, a
special type of track construction, and track bumpers that may be installed on spurs and sidings.
2.30.
STUB SWITCHES OVERSEAS
Although the stub switch is practically obsolete in this country, as paragraph 2.4a explains, it is of
interest to military track supervisors because it may be found in many oversea areas. Its disadvantages are, first,
that high temperature may cause sufficient rail expansion to bind the movable rails in one position, preventing the
switch from being thrown to the alternate path. Second, the slightest maladjustment of the switch rails can result
in derailments. However, because of the urgent need for rail transportation and the scarcity of supply parts in a
theater of operations, this switch may be used in spite of its poor design. All that is necessary to construct such a
turnout are switch ties and a suitable frog; the switch itself can be made of standard rail.
2.31.
SPRING SWITCHES
A spring switch is actually a split switch incorporating a throwing mechanism that permits a train to make
a trailing-point move no matter for which direction the switch is lined. This is done by having the switch points
held in normal position, that is, set for main line, by springs mounted in cylinders and attached to the switch-rod
assembly. The wheel flanges of a train passing on to the main track from the turnout side force the switch point
over against spring tension without damaging the switch stand or operating mechanism. After the train has
passed, the springs return the switch points to normal position. An oil cylinder and a buffer-plate assembly
prevent the switch from returning to normal position too quickly, which would be damaging to the entire
mechanism. The switch is usually constructed so that it can also be manually thrown for facing-point traffic to
enter the turnout side. It is then set for the turnout.
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