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You are here: Home > Forum > Miscellaneous > The real thing (signalling) > On and Off

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On and Off 27/07/2010 at 12:16 #1507
Wibblebutt
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10 posts 		I know that when a signal is described as being 'off' it has been cleared by the signalman. Am curious as to the origins of the terms though. Why are they 'on' and 'off'?

Something to do with the position of the levers?
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On and Off 27/07/2010 at 12:16 #10254
Wibblebutt
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10 posts 		I know that when a signal is described as being 'off' it has been cleared by the signalman. Am curious as to the origins of the terms though. Why are they 'on' and 'off'?

Something to do with the position of the levers?
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On and Off 27/07/2010 at 13:01 #10255
ralphjwchadkirk
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275 posts 		If it is OFF, the red light is off, and the signal must be showing a proceed aspect.
ON is when there is no proceed aspect,

I don't know where the phrases came from though!
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On and Off 27/07/2010 at 13:28 #10256
Danny252
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1461 posts 		The thing is that the term seemingly dates back to semaphore days (I hear the terms used on a constant basis when discussing lever frames). Therefore red light off/on would seem slightly odd, as although lights were used at night, it was technically one lamp being used with different lenses being put over it, so no light was ever turned "off" or "on".

In relation to levers, they are generally referred to as "Normal" and "Reverse" - stemming from being in the Normal position and Reverse position. I've never heard these called "on" or "off", other than in reference to changing the aspect of a signal - so "Pull off 131" would only be valid if 131 were a signal, and not points/FPL/whatever.

Interestingly (to me!), you don't "Put On" a signal, instead you "restore it", "replace it" or "put it back [in the frame]".

The two that come to mind as reasons for off/on are:
* Train On Line (Danger), Train Off Line (Clear)
* Something to do with track circuiting - the circuit would be "on" when a train is on the line
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On and Off 27/07/2010 at 15:02 #10257
clive
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2737 posts 		I'm sure it's not to do with either lights or track circuits: it's too old for that.

My guesses are, that either:
(1) it derives from "let them off", in the sense that the "off" is the start of a race and the signal lets the train go; or
(2) as Danny hints, a signal indicates that there's a train (or other danger) "on" the line ahead, so if there's no train the signal can be "off.

More research required.
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On and Off 27/07/2010 at 15:27 #10258
panelbeater
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11 posts 		I have always been told that the terms "on" and "off" predate the railways use of semaphore signals. Their origin dates back to the use of semaphore arms for sending messsages over long distances.
When a message station was in use, or switched "on", the semaphore arms were visable as were early semaphore signals when showing stop.
When a message station was not in use, or switched "off" the arms were dropped down in line with the support post as were early railway semaphore signals when showing proceed.
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On and Off 27/07/2010 at 17:18 #10265
Late Turn
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696 posts 		My understanding (well, what I've been told!) is that it dates back to the days when signals consisted simply of a board (and associated lamp?), and authority to proceed was given by the absence of the board. Thus, in a basic hand-worked installation, in order to allow a train to proceed, the board would be taken "off", and put back "on" to indicate Danger.
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On and Off 27/07/2010 at 18:40 #10268
Danny252
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1461 posts 		Late Turn said:
My understanding (well, what I've been told!) is that it dates back to the days when signals consisted simply of a board (and associated lamp?), and authority to proceed was given by the absence of the board. Thus, in a basic hand-worked installation, in order to allow a train to proceed, the board would be taken "off", and put back "on" to indicate Danger.
That triggered something in the back of my mind - I vaguely remember being told something about boards being rotated, so that when at danger, they were Face On to the driver, and when clear, the board was rotated 90 degrees so that it was edge on - therefore "Face Off"?
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On and Off 27/07/2010 at 19:22 #10270
Late Turn
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696 posts 		Yes, some early signals did take that form. I don't know for certain whether a variant on that was a board that was removed by hand to give the same pair of indications, hence the origin of the terms as I know it.
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On and Off 27/07/2010 at 19:39 #10271
UKTrainMan
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1803 posts 		Might these "board" things you talk about be covered on either this page or this page?!! Failing that, check out the rest of the excellent site (RailSigns.co.uk) - Who knows, maybe it might answer the original question! :)

NOTE: Both links to the individual pages have more than one page so ensure you check out all the pages.
Any views and / or opinions expressed by myself are from me personally and do not represent those of any company I either work for or am a consultant for.
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On and Off 27/07/2010 at 20:09 #10272
Late Turn
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696 posts 		The first set of pages you link to shows the boards that I refer to. Incidentally, I'm pretty sure that's the origin of the use of 'board' as an unofficial term for a signal - the current use of "the board's off" seems remarkably similar to the previous action of taking the board off!
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On and Off 27/07/2010 at 22:22 #10274
Wibblebutt
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10 posts 		Interesting discussion, glad I asked the question.

Those early board signals do seem to be the answer
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On and Off 27/07/2010 at 22:35 #10275
Danny252
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1461 posts 		I'll see if I can find out anything more at the weekend - spending it surrounded by people far more educated than myself in these matters! It may well have been one of those who told me originally.
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On and Off 28/07/2010 at 09:29 #10278
kbarber
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1711 posts 		I also believe it relates to taking a board (or indeed flag) off its post to indicate proceed.

Somewhere I once saw a very early GWR instruction quoted, regarding a "ball signal" at Reading. That worked the other way about though (but still not quite failsafe), the instruction being quoted as "...when the ball is not visible the train must not pass it."

Even when semaphore signals became the norm, they were made of wood until the 1920s or so; a common size would be 5 feet long and almost a foot wide, so "board" was still a pretty good description.

It's quite a testament to the power of tradition that even today the likes of Matt sitting clicking at a VDU "pulls off his boards".
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On and Off 28/07/2010 at 10:29 #10279
caedave
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142 posts 		Yes, it is this instruction that led to the later Disc and Crossbar signal, thus giving the two positive indications.
Bar ON=Stop, Disc On=Proceed.

Dave M.
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On and Off 28/07/2010 at 10:43 #10280
ralphjwchadkirk
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275 posts 		'Normal' and 'Reverse' come from the lever being in the frame (normal) or out of the frame (reverse). It is only really used now days in respect to point work.
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On and Off 28/07/2010 at 13:40 #10282
Danny252
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1461 posts 		kbarber said:
Somewhere I once saw a very early GWR instruction quoted, regarding a "ball signal" at Reading. That worked the other way about though (but still not quite failsafe), the instruction being quoted as "...when the ball is not visible the train must not pass it."
Somewhere in Chapter 1 of Red For Danger (my current bit of reading material!), I believe.
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On and Off 28/07/2010 at 21:43 #10313
DriverCurran
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682 posts 		Danny252 said:
In relation to levers, they are generally referred to as "Normal" and "Reverse" - stemming from being in the Normal position and Reverse position.
Levers can have upto 5 positions as they move across the quadrant and indeed if you have a push-pull lever these would normally sit mid stroke. It would be quite common for the S&T techs to ask the duty signalman to place the lever mid stroke as part of testing.

Paul
You have to get a red before you can get any other colour
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On and Off 30/07/2010 at 13:17 #10343
Danny252
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1461 posts 		DriverCurran said:
Levers can have upto 5 positions as they move across the quadrant and indeed if you have a push-pull lever these would normally sit mid stroke. It would be quite common for the S&T techs to ask the duty signalman to place the lever mid stroke as part of testing.

Paul
Another example that comes to mind is switching out levers, with positions along the lines of "Switched In", "Switching In", "Switching Out" and "Switched Out". I've also seen other examples, mostly for levers that control electrical apparatus - interlocking levers and similar (although sometimes an explanation as to their actual use is hard to come by!).
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