shunt signals on LT/LU

[neilw]

Sorry to ask a basic question, but something has piqued my interest. Typical (disc) shunt signals turn through 45 deg in an anticlockwise direction when they show OFF. Is this or has this been universally the case, or have some cleared in the other sense?

[rincew1nd]

I'm willing to get GWR signals went the other way.

[quex]

Some early shunt signals - in particular on the London & North Western Railway - rotated around a vertical axis. The aspects were effectively painted on the side of a box that turned on this axis, so that one aspect was face-on to the driver and the other side-on/at 90 degrees.

photo from RMWeb

[Chris M]

In terms of mainline practice, www.railsigns.uk/sect3page2/sect3page2.html notes that similar shunt signals "a centrally pivoted arm, coloured red, inside a circular frame." introduced by the Glasgow & South Western Railway from July 1898 rotated either way. (diagrams 3.36 and 3.37). Diagram 3.49 on the same page shows a SE&CR shunt signal dating from 1920 that rotated clockwise to indicate off. Diagram 3.78 at www.railsigns.uk/sect3page4/sect3page4.html illustrates a Southern Railway floodlit shunt signal (described as "obsolescent") that rotated clockwise.

[tjw]

LB&SCR shunt signals were quite special, also rotating in a vertical axis.

www.lbscrmodels.co.uk/page57a.html

Scroll down this page for colour photo, www.bluebell-railway.com/brps/signals-signalling-how-it-works/

[pgb]

Mar 6, 2021 10:57:13 GMT rincew1nd said:

I'm willing to get GWR signals went the other way.

I'm not sure they did - which I find a bit unusual!

[neilw]

Sorry, should have clarified I meant Ones on LT/LUL

[billbedford]

Mar 6, 2021 13:52:15 GMT Chris M said:

In terms of mainline practice, www.railsigns.uk/sect3page2/sect3page2.html notes that similar shunt signals "a centrally pivoted arm, coloured red, inside a circular frame." introduced by the Glasgow & South Western Railway from July 1898 rotated either way. (diagrams 3.36 and 3.37). Diagram 3.49 on the same page shows a SE&CR shunt signal dating from 1920 that rotated clockwise to indicate off. Diagram 3.78 at www.railsigns.uk/sect3page4/sect3page4.html illustrates a Southern Railway floodlit shunt signal (described as "obsolescent") that rotated clockwise.

I practice ground signal would only rotate in one direction, I never heard of one that could give three different aspects. Which way they turned, I would guess, would depend on whether the normal semaphores were upper or lower quadrant. 

[Chris M]

Indeed that was sloppy wording on my part, they only rotated one way. However One of them I mentioned (I can't remember which) did show three positions - horizontal, 45° and vertical.

[d7666]

In general, if main arms were lower quadrant then disc rotates anti clockwise so both go from - to / or upper quadrant then clockwise so both go from - to \

HOWEVER this got muddled when railways and or sites and or individual signals changed from lower to upper quadrant arms

GWR retained lower quadrant hence anti clockwise

[tut]

d7666 has summed the situation up perfectly with regards to upper and lower quadrant. I know of no recent LU examples of upper quadrant shunt signals (i.e. clockwise rotation) although I'm not sure about the misty old days of yore. There was definitely an upper quadrant disc at Quainton Road prior to closure (dunno if it was there when Metropolitan Line trains were still to be seen mind, probably not), and there could easily have been others on lines served by Underground trains. On the National Rail network upper quadrants are certainly to be found, see for example

www.flickr.com/photos/ingythewingy/7541950486/ and www.flickr.com/photos/pwayowen/48330997631/

Edit: Stoke Mandeville had an upper quadrant disc which was in service in Metropolitan Line days.