Model Railroad
Turnouts:
Introduction:
A
railroad
switch, turnout or (a set of) points is a mechanical installation
enabling
railway
trains to be guided from one
track
to another at a
railway junction.
Turnouts,
points or switches
are
sections of track that allow trains to travel from one line of track to
another. The points control which way the train will go. The switch rod
is connected to the points and is pulled back and forth by the switch
mechanism which can be either a ground throw (a lever operated manually)
or by an electrical switch machine like a solenoid motor. Whichever
switching mechanism is used the basic effect is that the points are
changed from one side to the other which then changes the direction of
the train.
The switch
consists of the pair of linked tapering rails, known as points (switch
rails or point blades), lying between the diverging outer rails (the
stock rails). These points can be moved laterally into one of two
positions so as to determine whether a
train coming from the narrow end will be led towards the
straight path or towards the diverging path. A train moving from the
narrow end towards the point blades is said to be executing a
facing-point movement.
Unless the
switch is locked, a train coming from either of the converging directs
will pass through the points onto the narrow end, regardless of the
position of the points, as the vehicle's wheels will force the points to
move. Passage through a switch in this direction is known as a
trailing-point movement.
A switch
generally has a straight "through" track (such as the main-line) and a
diverging route. The handedness of the installation is described by the
side that the diverging track leaves. Right-hand switches have a
diverging path to the right of the straight track, when coming from the
narrow end and a left-handed switch has the diverging track leaving to
the opposite side.
A straight track
is not always present; for example, both tracks may curve, one to the
left and one to the right (such as for a
Wye
Switch) or both tracks may curve, with differing
radii, in the same direction.
Generally, there
are two types of model railroad turnout, insulated and power routed.
Insulated
turnouts are easier to wire and install. They conduct power to both the
main track and the diverging (branching) track at all times. If you want
the branch track to be isolated, you will have to add a rail gap to the
positive rail of the branch near the turnout, then add a feeder wire to
that branch controlled by a switch on your control panel. The frog is
insulated so that no power is supplied to the locomotive wheels at that
point. There are small hidden wires in the track ties that supply power
to the two track routes so that power gets to all the rails all the time
and since the frog (where the tracks cross) is insulated, there are no
short circuits as the train passes over.
Power-routing
require a little more thought in the wiring process, but have some
advantages over the standard type. The main advantage is that the power
to your branch is controlled by the direction of the points. Because of
this, you only have to throw one electrical switch to change the
direction and power the branch at the same time. You won’t need rail
gaps for the branch in this case (unless the branch is receiving power
from somewhere else); and you won’t need a separate electrical switch to
turn the branch track on or off. However, you will need rail gaps on the
frog end of the through track. These types of turnouts are a little
harder to come by. Many hobby shops don’t carry them; you may have to
order them through a catalog or online. They are produced by Walthers,
Peco, Shinohara and Micro-Engineering only in HO and N scale