Clearing subsidiary signals.

[olivegreen]

I have just caught up with this discussion, and have to say that THIS is what makes RMWEB worth following: an intelligent exchange of information on a rather technical topic. No infantile whining here about whether X manufacturer's timescales, rivet sizes or colour schemes suit Y's layout!

 

Many thanks to the contributors so far - I have learned a lot.

Mike

[The Stationmaster]

Ever so slightly off topic....

 

This is one of the subsidiary signals in shrewsbury, it may look like its a normal stand alone shunt disc but its actually the sub for the main signal on the right which is for the centre of the 3 roads! (It's located on the wrong side, my locos signal is on the platform!)

 

 

 

If you get the sub at that signal you take the left hand diverging road into abbey forgate yard and your next 'signal' is a stop board, ive done it once with the logs when the box couldnt pull the main signal off, if you get the main signal you to round to the next semaphore (that you may be aboe to make out the o the extreme left of the picture) and that has a sub to take you into the other end of the yard!

 

Good old shrewsbury

In this case it is actually a co-located disc and is actually working as a somewhat oddly arranged splitting signal (not the disc has a red light).  In earlier GWR times it would have been a centre pivot arm bracketed off a normal signal postGWR times - rather like the somewhat oddball example at Slough seen bottom left in the pics below (although in that case the running arm - which applied to a passenger line - was a short one for loading gauge reasons)

 

[The Stationmaster]

Fouling bars are the generic term , describing a mechanism that the wheel interfered with a long bar to active a certain function , in FPL these are then actually known as locking bars  http://www.irse.org/minorrailways/publicdocuments/PA01%20-%20Mechanically%20Operated%20Points%20v2.pdfpage 11

 

in the case of situations where a clearance distance had to be maintained out of sight of the signalman, sometimes a fouling bar was used, in that case it was known as a clearance bar.

 

in the same vein a vehicle is a generic for a car and a lorry 

Well not quite - Fouling Bars, also known more commonly as Clearance Bars serve(d) a specific purpose although some signal engineering sources use the word 'fouling' for all of them - even in at least one publication instead of the term Facing Point Lock/Locking Bar (use of Lock or Locking seemed to vary according to where you worked/were brought up.

 

In my view it is far sensible when discussing signalling to avoid confusion and refer to such bars by their function rather than any generic engineerng term - for example we could equally just call a signal a signal irrespective of its purpose or meaning.

[ColHut]

Re-reading all this now, notwithstanding the various historical oddities, it all makes a lot more sense.

 

Some very knowledgeable people here.

 

regards and thanks