GWR late pattern round post Ground Discs

[Junctionmad]

Can anyone tell me when these where introduced and were they area specific or did they appear all over the GWR/WR

 

has anyone a dimensioned sketch or a dimensioned photo , Im trying to do an O gauge model and 3D print the body 

 

 

thanks again 

 

dave 

[Junctionmad]

bump 

[Miss Prism]

I wish I had some dimensions to assist, but I don't. Here are some pics that might be useful:

http://www.gwr.org.uk/no-groundsigs.html

[The Stationmaster]

Can anyone tell me when these where introduced and were they area specific or did they appear all over the GWR/WR

 

has anyone a dimensioned sketch or a dimensioned photo , Im trying to do an O gauge model and 3D print the body 

 

 

thanks again 

 

dave 

 

Sorry Dave but I missed this post first time round.

 

They are very definitely Post-War and might even be post GWR but I think no later than c.1950 and possibly as early as 1946/47.  However once introduced they were the (G?)WR standard for single arm disc signals and therefore appeared in new work and as replacements but probably only after stocks of older signals were exhausted.  As far as I can trace they only ever appeared in a single arm version and I know (because I saw what was in the stores) that Reading Works had a very limited stock of the older pattern castings for 3 arm discs in the stores virtually up until closure.

[TheSignalEngineer]

I remember discussing this on the old Signalbox forum but unfortunately that is down now. I had a vague memory that they came in during the early 1950s.

[Junctionmad]

Thanks , I was wondering for a layout set at the end of the GWR , if it was appropriate to have some of them

[Miss Prism]

What I don't understand is the transition from 12" to 16" discs.

[The Stationmaster]

What I don't understand is the transition from 12" to 16" discs.

 

The only reason I can think of was to improve visibility.  But then of course they went back to smaller ones so might it have been a clearance issue too? 

[bécasse]

The only reason I can think of was to improve visibility.  But then of course they went back to smaller ones so might it have been a clearance issue too? 

 

I wonder if a more likely reason was standardising stores items. Given that the smaller discs still had to be held in store even for new works let alone for like-for-like replacements, there would have been a real cost to holding the larger discs too. As the railway became more cost-conscious it is a consequence that would have dawned on someone - it might even have come in as a staff suggestion.

[Miss Prism]

I don't think there would have been a clearance problem between two adjacent loading gauges, although I haven't checked it in actual dimensions, and in some cases it could have been tight. So visibility, perhaps for specific locations, seems the obvious reason for the change, but I can't pinpoint when the change started.

 

Not sure I buy the 'stores cost' argument though - the discs were bolt-ons to the cast front plate, so were easily interchangeable.

[bécasse]

 

Not sure I buy the 'stores cost' argument though - the discs were bolt-ons to the cast front plate, so were easily interchangeable.

 

 

Exactly my point, why hold two different sizes of enamelled disc when one size is sufficient, the smaller size being required in order to fit the multiple-disc design. Even if the bolt holes were differently spaced on the new-design single disc ground signal, it would have been a simple matter to start including the relevant bolt holes in the manufacture of the enamelled disc.

Sometime in the early-1960s (inspired by Beeching, perhaps), BR started to take procurement seriously and asked pointed questions about why something slightly different from standard was essential and why the standard item wouldn't do - I remember being asked to justify why a particular printed tabular document had to be totally reset every year, I pointed out that the calendar changed every year so days that matched to dates last year, didn't this, hence the resetting.

[Miss Prism]

Tim Venton reports that Adrian Vaughan calls the 16" discs the '1918 type'. These bigger discs were used mainly, but not exclusively, on main to siding movements, so it seems that improved visibility was the prime reason for using them, the objective being to make main to siding movements more effective. Tim stresses the 16" were not regarded as a replacement for the 12" discs, which continued to be widely used.

[The Stationmaster]

Tim Venton reports that Adrian Vaughan calls the 16" discs the '1918 type'. These bigger discs were used mainly, but not exclusively, on main to siding movements, so it seems that improved visibility was the prime reason for using them, the objective being to make main to siding movements more effective. Tim stresses the 16" were not regarded as a replacement for the 12" discs, which continued to be widely used.

 

That sounds a bit odd.  As far as I have been able to trace (I.e. not an ab solute comment) the '1918' (ish?) pattern succeeded the 1911 pattern and were in turn succeeded by a further design change in the late 1920s/early '30s which used the smaller (12") disc face which then remained the standard.  The 1920 General Appendix illustrates the original miniature semaphore arm pattern, the 1911 pattern, and what it refers to as 'the new pattern' and while the drawings are not to scale the comparative sizes of the signals makes fairly clearly that 'the new pattern' has 12" discs.  it has long been my understanding, although I can't recall where I got it from (sorry) that the larger pattern disc emerged during the 1920s but it will need a detailed study of photos - if they exist - or whatever Reading records and drawings survive to establish what happened when with greater precision.

 

PS If you happened to see what was in Reading's, let alone local S&T, stores as late as the 1970s/early '80s you'd be well aware that the GWR S&T was not overly concerned about keeping spare parts for all sorts of things that might well be considered obsolescent.  My disc pattern (i.e. pre 1947 style) block instrument came to me brand new ex stores in the mid 1970s and the same stores held, so I was told, so Midland Railway rotary block instruments.  Reading stores just before closure had several brand new corrugated UQ signal arms in superb condition.

Edited October 22, 2018 by The Stationmaster

[bécasse]

 

PS If you happened to see what was in Reading's, let alone local S&T, stores as late as the 1970s/early '80s you'd be well aware that the GWR S&T was not overly concerned about keeping spare parts for all sorts of things that might well be considered obsolescent.  My disc pattern (i.e. pre 1947 style) block instrument came to me brand new ex stores in the mid 1970s and the same stores held, so I was told, so Midland Railway rotary block instruments.  Reading stores just before closure had several brand new corrugated UQ signal arms in superb condition.

 

Not just Reading, of course. The Elephant Room at Wimbledon (SR S&T) in the mid-1960s could best be likened to Alladin's Cave, clearly, quite apart from new stuff, anything that had been recovered and was still serviceable had never been thrown away.

[TheSignalEngineer]

I was involved around 1970-71 with going through the stock at Soho S&T Stores to check why the value at stocktaking was so high. We had to check through every item on the list and identify whether the equipment was still in use on our Division. and offer anything that wasn't to Crewe S&T Stores and Telegraph Shops and the other stores throughout the country.

 

Besides a big range of old LNWR and Midland equipment there were still a few spares from the Siemens Miniature Lever frames and associated outside equipment for the old boxes at Snow Hill. Some of these had been manufactured by Krupps pre-WW1.