Lever colours & their relative positions

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mitchell1
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Joined: Mon Dec 24, 2007 11:10 am
Location: Canberra, Australia

Lever colours & their relative positions

Post by mitchell1 »

In a real signalbox how were the levers grouped? Were all black levers grouped together, with the red levers next to them, etc? Or were they sprinkled out in geographical position from left to right of the signal diagram, with colours almost at random?
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DKM
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modadmin
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Location: Australia

Post by modadmin »

A typical arrangement for a through station would have the points and FPL levers (blacks and blues) located in the middle of the frame in a generally geographical left-to-right arrangement. To the left of these would be placed all signal levers relating to left-to-right movements, while signal levers relating to right-to-left movements would be placed to the right end of the frame.

One reason for this arrangement is that it easily facilitates conditional interlocking where it is typical for the interlocking between up and down signals to be conditional upon the state of points.

With the signals/points/signals configuration, it is common that the main through routes be controlled by the outermost signal levers, e.g. the up distant, up outer home, up home, up starter and up advanced starter might be controlled by levers 1, 2, 3, 4, 5 respectively, or, if the up movement were right-to-left with respect to the frame location, and the frame had, say, 24 levers, then the levers to control the through movement might be 24, 23, 22, 21, 20.

Even though the general arrangement of a frame may be as described, there may also be localized pockets of geographical layout. As an example, there may be a trailing crossover where setting back moves are controlled by shunt signals. This set of devices may be connected to three adjacent levers red - black - red for convenience.

Some considerations in deciding the location of levers include:

Pulling order - the ideal is that the levers to be pulled to achieve a particular move should be in a consistent left-to-right or right-to-left order to minimize the need for the signaller to change direction while setting up a route.

Pulling between - the ideal is that a signaller should never be required to pull a lever that is located between two other levers that may already be reversed.
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