2.37.
SUMMARY
Although becoming obsolete in this country, stub switches may be found overseas. Expansion because of
high temperature may cause binding of the stub switch's movable rails, thereby preventing their being thrown.
Even a slight maladjustment of such a switch may cause a derailment. Switch ties, a suitable frog, and standard
rail are all that are needed to construct a stub switch.
A spring switch is nothing more than a split switch designed to allow a trailing-point move through it,
even though it may be lined for facing point. A derail runs equipment off the rails to prevent collisions, cars
from running away, and fouling of a main track. Both split-point and frog derails may be used. A split-point
derail has no frog and only one switch point. The frog derail fits over one rail and guides the wheel flange up,
over, and away from the rail.
When two tracks cross at grade, frogs must be installed to allow the wheel flanges to pass along both
tracks. The end frogs are usually the conventional rigid and movable-point ones; those in the center are specially
designed. Rigid frogs give a rough ride and are more dangerous than movable-point ones in a wide-angled
crossing.
With switch rails added to a movable-point frog, it becomes a double slip switch. When entering it from
either direction, a train can be diverted to either track at the other end of the switch. Although it saves space and
provides train-movement flexibility, the switch is difficult and expensive to maintain.
Gantlet tracks, which provide a double track in a space where ordinarily only one track would be found,
have two frogs but no switch rails. Track bumpers are used at the end of dead-end tracks to forestall derailment
and to safeguard structures. Such tracks are found on industrial spurs and blind sidings among other locations.
Track bumpers may consist of commercially designed manganese steel bumpers, concrete blocks, earthen
mounds, or timbers.
Up to this point, the discussion of railway track maintenance has been confined to straight or tangent
track and the switches, frogs, and other equipment used to permit a train to go from one track to another. Next,
the railway curve, used to change the direction of a rail line, is discussed.
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