Re: Triangular colour light ground signals?

The signals you describe (I think) are ground position lights (or 'dods' as we call them).

The top colour is white, and when in the off position, the red aspect in the bottom left goes out and is replaced by the white light in the top position.

Giving a white: \ \

Just because they are triangular, doesn't necessarily indicate a turnout, they usually are placed either on a turnout, or where you proceed over a trailing junction (where a route indication isn't necessary). They are basically used in place of a full signal because they are a lot cheaper and easier to use.

The can also be used as position lights on main signals indicating permissive working, and can have different colours (two red aspects on the bottom row = limit of shunt) to show different things.

Hope this helps


Hi all. > > Please can anyone describe the workings of the ubiquitous triangular dwarf > signals which populate the UK network? > > I am modelling some of the little critters in N gauge (no problem!), and > despite staring at several examples for hours on end (well, minutes...) I've > never seen one change aspect. I know this much of the lights and layout > thereof: > > * < colour? > red > * * < white > > Since they are triangular, this would sugest they indicate turnout > direction, but... how? > > TIA for any info. > > whokid > > ----------------------------------------------------- > > Pester me, why not: whokid at flywheelnetwork .co .uk >
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The Irish Driver
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These are shunting signals, ie used to control various shunting movement. Examples might be found around a larger station where locos need to run round, or stock moves between different platforms or off to carriage sidings. They come in various configurations:

r=red, w=white, y=yellow, (off) R=red, W=white, Y=yellow, (on) b=blanking plug

  1. The most common one I should think, in on and off mode. Off, ie with two white lights, permits the shunting movement.

w W R W r W

  1. Less common, the red light is replaced by blanking plug, so the signal only displays the white aspect. Usually (?) mounted adjacent to a full-size signal head, ie where there is no need to display the R/W aspect to prevent train movement.

w W b w b W

  1. Much rarer is the warning signal, like 1 but with a yellow instead of a red.

w W Y W y W

  1. Becoming more common is the LED version of 1 in which the light at the bottom right corner can show both red and white, so the two aspects can be

w W R R r W

Note that in none of these cases do they indicate turnout position. They do not have to be mounted at a turnout although often are in practice. To display routes there may be multiple ground signals or separate route indicators.

They are equivalent to the semaphore ground signals which were white discs with a red or yellow horizontal stripe. The signal was "on" when horizontal and off when up or down, depending whether the main installation was upper or lower quadrant.

Not meant to be definitive but I hope it gives the general idea. Simon.

Reply to
Simon Harding

Thanks for the info, folks! I appreciate it.




Pester me, why not: whokid at flywheelnetwork .co .uk

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