| In
Illustration 1, both throw bars are to the right, making the train go
left. You can see that the left and center frogs are both of the red
polarity. In this situation, the polarity of the right frog is irrelevant.
In Illustration 2, throw bar #1 is
to the left and throw bar #2 is to the right, making the train go straight.
You can see that the left frog has green polarity and the right frog
has red polarity. In this situation, the polarity of the center frog
is irrelevant.
In Illustration 3, both throw bars
are to the left, making the train go right. You can see that the center
and right frogs are both of the green polarity. In this situation, the
polarity of the left frog is irrelevant.
At no time do the center and right
frog have to have different polarities. They are either of the same
polarity (Illustration 3) , or one or the other is irrelevant. This
is how the right and middle frogs can be tied together to have the same
polarity. So, all we have to do is figure out how to control the frog
polarities with the two throw bars.
By using a set of Single Pole Double
Throw (SPDT) contacts on the switch motor, or a micro switch on throw bar #2 (the bottom one),
we can control the middle and right frogs. When throw bar #2 is to the
left, it will feed green polarity to those frogs so the train can go
to the right. When throw bar #2 is to the right, it will feed red polarity
to those frogs so the train can go straight or to the left.
By putting a set of Single Pole Double
Throw (SPDT) contacts on throw bar #1 (the upper one), we can control
the left frog. When throw bar #1 is to the right, it feeds red polarity
to the left frog so the train can go to the left. With throw bar #1
to the left it feeds green polarity to the left frog so the train can
go straight. If the train goes right, the left frog is not used, so
it is irrelevant. |
