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LNWR Block Instruments

British signalling of the past (UK, excepting Northern Ireland)

LNWR Block Instruments

Unread postby Ashley Hill » Sun Mar 12, 2017 11:26 am

On LNWR block instruments the standard position for the tapper seems to be to the bottom right of the case. In the LMS film Sentinels of Safety instruments are shown with the tapper in the top right corner above the commutator. I have never seen an instrument of this type in the flesh, either at auction or in collections​. When was the tappers position changed and do any of the high tappers survive?
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Re: LNWR Block Instruments

Unread postby Mike Hodgson » Sun Mar 12, 2017 2:48 pm

I have been given to understand that as designed the tapper was originally in the top right hand corner of the square piece of wood below the dials as you say, but as LNW block shelves were fairly high anyway this made the tapper difficult to reach across the frame especially with levers reversed. I think these were mostly converted and later examples were built with the tapper in the bottom right. I have never seen one with the tapper in the upper position, although I suspect some escaped (NRM collection perhaps ?). Quite a lot were evidently taken out of service by the LMS and found their way to Scotland to replace 2-position blocks, so it is possible that surviving non-standard ones may have been scrapped. Unusual Fletcher blocks I have seen include one with two tappers (bottom left and bottom right), although i can't remember where, also I have one here which has its face printed in the style of standard LYR blocks - presumably done during the brief period the LNW owned the LYR prior to Grouping.
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Re: LNWR Block Instruments

Unread postby Chris L » Sun Mar 12, 2017 3:28 pm

Mike,

I think the L&Y faces were fitted to LNWR blocks when they were installed (as replacements by the LMS?) in ex-L&Y boxes.

I have seen photos of several such instruments with L&Y faces (mostly permissive) in L&Y boxes around the Bury area (on the east -west line, not the north-south!) and around Blackburn Station.

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Re: LNWR Block Instruments

Unread postby Ashley Hill » Sun Mar 12, 2017 4:50 pm

Thanks for replying. The nearest I've come to one was an instrument with a bottom door that didn't match the body. Could have been either a conversion or repair. Indeed they would have been a disadvantage to the shorter signalman.
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Re: LNWR Block Instruments

Unread postby Ashley Hill » Sun Mar 12, 2017 5:32 pm

Talking of Fletcher blocks,what was the deal with the Permissive flap on the standard instruments. Was this just a money saving exercise to save installing proper permissives on quieter lines or a more bone fide reason?
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Re: LNWR Block Instruments

Unread postby Mike Hodgson » Sun Mar 12, 2017 6:02 pm

I think they merely served to remind which set of rules you were currently working to, for lines where you would work goods permissively but still had a passenger service which required institution of AB. The flap is not mentioned in the LNWR 1916 regulations, either under the 3-wire instruments (AB) heading or under the Permissive Block heading which is specifically for the proper Tell-Tale Instruments. The regs don't specify how you switched between the two systems. Nor can I find it in the Special instructions to Signalmen chapter at the back of the book.
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Re: LNWR Block Instruments

Unread postby John Hinson » Sun Mar 12, 2017 6:33 pm

Ha ha, if you wre as old as me you would remember that type of instrument here and there in the seventies - they certainly weren't rare. They seemed to be concentrated in LNW boxes rather than other boxes on the LMR with LNW instruments, and mostly in larger boxes from memory. Did not that type have different legs too?

The two-tapper type were typically found where different boxes worked Up and Down lines - both at large stations and at places like Talacre - https://signalbox.org/diagrams.php?id=1146 .

I suspect (without looking) the arrangements for converting Permissive to Absdolute Block is found in the General Appendix under "Working of Passenger Trains over Goods Lines" and it entails sending a Block Conversion Ticket through on the last train before it is required. The ticket tucked nicely behind the flap on LNWR instruments but not, unfortunately, on the early BR standard instruments that had a similar fitting..

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Re: LNWR Block Instruments

Unread postby John Hinson » Sun Mar 12, 2017 6:46 pm

Dr Scrimgeour to the rescue!

I only had to look as far as the letter A to find a picture showing two such instruments (not to mention an early-style block switch), not the best quality but it is only the corner of the original picture:
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Photo: Ashton Moss Junction, Dr JWFS Scrimgeour May 1955.

Not the type with the different type of legs, as it happens.

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Re: LNWR Block Instruments

Unread postby Mike Hodgson » Sun Mar 12, 2017 7:41 pm

Yes, I had completely forgotten the change in the legs from the cast frame shown above to the more common tubular type.
Block conversion ticket and the GA sounds right John, knew I had seen something somewhere relating to BR era, but only as something I would expect to be infrequent - exceptional need to use goods lines for passengers etc.

Would that procedure have been the case back in LNW days too though - or would it have been less formal, perhaps daily or even more often ? I have read of routine switching from AB to Permissive elsewhere (LYR or perhaps NER), with even wrong line operation being used routinely after last passenger train of the day.
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Re: LNWR Block Instruments

Unread postby Ashley Hill » Sun Mar 12, 2017 7:56 pm

What a splendid photo. I have seen some bottom tappers with legs like those which supports the conversion statements. Even so does anyone have a "high tapper" in their collection?
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Re: LNWR Block Instruments

Unread postby John Webb » Sun Mar 12, 2017 8:00 pm

We've several LNWR block instruments at St Albans South - I'll check what we've got later in the week when I'm back up there.
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Re: LNWR Block Instruments

Unread postby Ashley Hill » Sun Mar 12, 2017 8:17 pm

The two shown in your locking room photos have the bottom tapper.
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Re: LNWR Block Instruments

Unread postby railman » Sun Mar 12, 2017 8:48 pm

Sold a high tapper a cople of weeks ago.... in working order.
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Re: LNWR Block Instruments

Unread postby Ashley Hill » Sun Mar 12, 2017 8:51 pm

It's good to know there is still some about.
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Re: LNWR Block Instruments

Unread postby Ashley Hill » Mon Mar 13, 2017 4:58 am

So on the two tapper blocks did the opposite boxes share the same underslung bell or was an additional one provided?
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