The Interlocking Plant

Model Railroader Electronics and DCC
1

LION likes interlocking plants. And it helps make sense out of a model railroad. It really does help visualize reversing loops and wyes. It also demonstrates how to gap and block a reversing loop, since if a track returns from the east end to the west end, then it is a reversing loop and that is the track that requires proper gaps for electrical continuity.

Interlocking machines, from the steam era, and still operated into this century, are an integrated whole. The interlocking machine, the switch machines, and the signals are all made by the same company and cannot be used with other kinds of equipment.

The most ancient, and possibly well known is the US&S “armstrong” machine. That is to say the old levers in which the wherewithall for moving a set of switchpoints comes from the box of Wheaties that the operator had for breakfast. This wouold not need to show up in a discussion on the Electronics forum escept of course, that we do use electric parts to make our railroads work, and knowing what they did helps us to know what we want to do, even if we are just going to use electric switches.

On the “Armstrong Machine”, two levers must be moved to align a set of switchpoints. First a lever must be used to unlock the switch points, then a second lever is used to move the switch points, and finally the first lever must be returned to the lockied position. If one of these levers cannot be moved (The lock for example) there may be a chunck of ice or a piece of ballast that is blocking the movement. The tower operator will have to go down to the tracks and correct this, and then come back to the tower to make the lever movements. If the point lever will not move, or the lock cannot be unlocked, then the machine itself is controling the situation with a bed of heave brass rods under the floor of the tower that prevent settting up a conflicting alignment. Once the plant is fully aligned, the the signal levers can be moved to give a train aughority to pass through the plan

2

As shown on the model board, the whole layout is one big reverse loop. The crossover on the far left make it so. I assume there’s more, because if the model board schematic is accurate, there’s no place for continuous running there. Or is there no continuous running?

–Randy

3

The express tracks loop back on each other, but of course only the portions shown are on this model board. It is to be assumed that there are seperate interlocking plants for both Lenox Avenue and for Nevins Street. There are none, they just loop back on each other in the same direction they were going, but there are crossings that will move trains to and from the local and express tracks.

As for the Mane Lion, there surely is “continious” running, but the tower operator must be a juggler. Him can have five or six trains out on the road, but must keep making room for incoming by dispatching the outgoing. There are layup pockets for parking trains at night when headway is increased to 20 minuytes and the work trains come out to play.

The mane line surey does look like a reversing loop, but electrically it is not. The double crossover at 242nd Street is completely electrically dead, and the terminal tracks are powered by whatever track they are aligned with.

Since my trains have 48 wheel pickup, I figured the heck with trying to wire the crossover.

ROAR

4

The NYCTA has tracks where the direction of traffic may be reversed. The GRS and US&S interlocking machines use a lever painted Blue to control the direction of traffic. This lever locks the opposing signals so a train cannot enter from the wrong direction. The levers have to be in sync at the towers at both ends of the reversing section. If you do have a reversing section, a lever can be used to reverse the track power instead of an AR unit.