Diesel loco headcode discs-purpose in later years

[rodent279]

Back in the days when trains were identified by the position of lamps, as on steam locomotives, I can understand discs and marker lights being provided in a similar fashion on the early pilot scheme diesels. Some lasted until very late, see attached (poor) photo of 20105 at Skegness, Sept 1990, with a full complement of discs, all unfolded.

But did they have a purpose in later years? Were they a requirement? Did they get removed?

 

Edited May 23, 2021 by rodent279

[black and decker boy]

Just an ornament. Some locos kept them, some had them removed (eg 20016) and just the lamp lenses retained. Some lost the lower centre one for a High Intensity headlight.

 

Train crew liked to mess with them I think :-) 

[Andrea506]

All four open like in the picture denotes "The Royal Train".

[HGR]

When headcodes went out of use in the '70s the white disks were supposed to be removed and the bulbs and fittings and / or wiring disconnected from the centre and top positions so as to leave the other two outer lamps remaining visible as marker lights as per the new requirement.

 

Unsurprisingly there were plenty of variations on implementation of this, and the time taken to apply.

 

As pointed out above, the centre position formed a useful starting hole for the later headlight fitment. The drawings issued for this modification sort-of took this into account in the selected position / measurements for classes / batches of locos that previously had disks in deciding where to set-to with the hole saw.

 

[The Stationmaster]

Headlamps/disc headcodes were officially out of use no later than early December 1976 

[F2Andy]

Why were locos with discs never converted to headcodes? It seems an obvious thing to do (pre '77), once headcodes became standard. A lot of classes had examples that were built later with headcodes, so the design work was done - someone had already decided where they would go and what they would look like.

 

Or did that happen, and it was so slow they were still getting through them when headcodes were abandoned?

[rodent279]

35 minutes ago, F2Andy said:

Why were locos with discs never converted to headcodes? It seems an obvious thing to do (pre '77), once headcodes became standard. A lot of classes had examples that were built later with headcodes, so the design work was done - someone had already decided where they would go and what they would look like.

 

Or did that happen, and it was so slow they were still getting through them when headcodes were abandoned?

Some were converted, Baby Deltics for example, after rebuilding. I think classes 21/22 also got headcode boxes fitted after rebuilding.

Some Scottish class 40's with discs were retrospectively fitted with headcode boxes, and Warships also were originally built with discs, and later converted to headcode boxes, though I'm not sure how many.

Edited May 28, 2021 by rodent279

[rodent279]

A slightly different slant on the original question is when is the latest that headcode discs would be required to be used, as opposed to train crew messing about with them for fun? Would a blue TOPS numbered diesel ever have been required to use discs to display a headcode for a train?

 

Edit:-a quick trawl through Flickr seems to indicate that headcode discs were still largely being used, where fitted, to indicate the class of train up to around 1975-6. After that they could still be seen, but not necessarily in accordance with the train, class 1 headcode on ballast trains for example.

Edited May 28, 2021 by rodent279

[keefer]

The  date usually mentioned for stopping the display of headcodes is January 1976 with the instruction that they should be wound to show 0000.

I would imagine they would still get used , as previously, after this date but with use tailing off over the year.

I don't know if it was something which was actively monitored/enforced by management though.

I suppose some crews would've been glad as the blinds could be a pain in the @rse but others would be quite happy to keep using them.

Various locos/units managed to keep their blinds into the early '80s - IIRC the 'BedPan' cl.127s mostly still had working blinds, often showing the correct headcodes, up until withdrawal in 1982/3

 

[The Johnster]

4 hours ago, rodent279 said:

Warships also were originally built with discs,

 

To be pendantic, not discs but GW/WR type 3-character train reporting number frames.

 

2 hours ago, keefer said:

January 1976 with the instruction that they should be wound to show 0000.

 

Which did not prevent them being used to display the locomotive number where this was possible, particularly on Class 52s, which never displayed their TOPS numbers because of the cast numberplates and the short life expectancy of the class.  Deltics could presumably have displayed the pre-TOPS numbers in the headcode box as well, but I have no idea if any ever did.  It was done by using the alphabet character O, originally used to indicate a train whose destination was the Southern Region, as the second number.  To be again pedantic, the number instructed was IIRC described in the instruction as '0000' but in reality was '0O00'

[BR60103]

A supplemental question, Mr Speaker.

 

Were the lamps behind the disks turned on individually or was there one switch and the disk covered up the light?

 

[rodent279]

8 hours ago, keefer said:

The  date usually mentioned for stopping the display of headcodes is January 1976 with the instruction that they should be wound to show 0000.

I would imagine they would still get used , as previously, after this date but with use tailing off over the year.

I don't know if it was something which was actively monitored/enforced by management though.

I suppose some crews would've been glad as the blinds could be a pain in the @rse but others would be quite happy to keep using them.

Various locos/units managed to keep their blinds into the early '80s - IIRC the 'BedPan' cl.127s mostly still had working blinds, often showing the correct headcodes, up until withdrawal in 1982/3

 

So was the requirement to show discs & lights in the appropriate positions, if no headcode box fitted, abolished on the same date?

[rodent279]

5 hours ago, The Johnster said:

 

To be pendantic, not discs but GW/WR type 3-character train reporting number frames.

 

 

Which did not prevent them being used to display the locomotive number where this was possible, particularly on Class 52s, which never displayed their TOPS numbers because of the cast numberplates and the short life expectancy of the class.  Deltics could presumably have displayed the pre-TOPS numbers in the headcode box as well, but I have no idea if any ever did.  It was done by using the alphabet character O, originally used to indicate a train whose destination was the Southern Region, as the second number.  To be again pedantic, the number instructed was IIRC described in the instruction as '0000' but in reality was '0O00'

I wondered about that-I thought that maybe only the first loco was built with discs, but this photo suggests that the first 13 were built with discs, and WR style reporting number frames.

There's a few other photos on Flickr of Warships from that batch with both discs and headcode frames.

Other locos to have been built with discs and converted to headcode displays was the class 28's, though I don't know if all were converted, at least one class 44 received a class 46 nose with a single central box, and the first batch of class 45's.

I don't think any of the class 15/16's ever had headcode displays?

Edited May 29, 2021 by rodent279

[black and decker boy]

11 minutes ago, rodent279 said:

 

Other locos to have been built with discs and converted to headcode displays was the class 28's, though I don't know if all were converted,

Do you mean the NB class 21 when converted to Class 29?

 

The Metrovick Co-Bo class 28 retained discs throughout

 

[rodent279]

26 minutes ago, black and decker boy said:

Do you mean the NB class 21 when converted to Class 29?

 

The Metrovick Co-Bo class 28 retained discs throughout

 

Maybe. I thought I'd seen a photo of a blue Co-Bo with a headcode display, but can't find anything on Flickr.

[rodent279]

6 hours ago, BR60103 said:

A supplemental question, Mr Speaker.

 

Were the lamps behind the disks turned on individually or was there one switch and the disk covered up the light?

 

This page is quite informative. I can't vouch for it's accuracy, but it implies they were independently switched.

http://www.2d53.co.uk/Headcode/headcodeC.htm

 

[HGR]

No, not independently switched on any classes that I am aware of. There was only one 'train classification lights' switch in each cab.

 

For disks, all four lamps would be turned on together if any disk flaps were to be open. If all flaps were closed, you could leave the switch 'off'. As you would also do for an intermediate or rear-facing cab - should have all disks closed. With the train classification lights switched 'on', any closed disk flap would obscure its corresponding lamp and not be visible. You might notice light leakage around the edge of the closed disk on night-time long exposure photographs.

 

On headcode locos in most cases there were two bulbs behind each character position. As most locos had duplicated lighting circuits, one bulb in each position would be fed from the No.1 lighting circuit, and the other bulb in each position on the No.2 circuit. That way if one of the circuits tripped out, half-lighting would still obtain.

 

The same duplication occurs with the red tail lights. One is fed by each of the two lighting circuits, but operated by the same one switch. So one circuit trip would allow the other tail lamp to still function.

 

When headcode boxes were fitted with circular opaque white disks to act as marker lights, there were two bulbs roughly behind each marker - bulbs 2+3 and 6+7, so usefully still one of each on No.1 lights and the other on No.2, the other four bulbs becoming handy 'spares'. The switch now being used for marker lights usually was still labelled 'train classification' on locos that previously had disks or headcodes.

 

[Phil Bullock]

2 hours ago, rodent279 said:

and the first batch of class 45's.

I don't think any of the class 15/16's ever had headcode displays?

The first class 45s D11 -15 had nose end doors as per the 44s but I have never seen one with discs ... entered traffic with split headcode boxes so no 45s with discs.

 

No class 15 or 16 ever had headcode boxes .... discs retained until the bitter end.
 

The WR rebuilt the most loco S with headcode boxes ... not only the first batch of warships but also D600-4 and D6300- D6333 except for D6301 which retained its discs to the end.

All Scottish class 29s gained headcode boxes when rebuilt from Class 21s except for the first conversion D6123 which retained discs.

 

So the Scots had a stab at replacing discs on a few locos but only the WR had a real go at total conversion.

Edited May 29, 2021 by Phil Bullock

[rodent279]

37 minutes ago, Phil Bullock said:

The first class 45s D11 -15 had nose end doors as per the 44s but I have never seen one with discs ... entered traffic with split headcode boxes so no 45s with discs.

 

No class 15 or 16 ever had headcode boxes .... discs retained until the bitter end.
 

The WR rebuilt the most loco S with headcode boxes ... not only the first batch of warships but also D600-4 and D6300- D6333 except for D6301 which retained its discs to the end.

All Scottish class 29s gained headcode boxes when rebuilt from Class 21s except for the first conversion D6123 which retained discs.

 

So the Scots had a stab at replacing discs on a few locos but only the WR had a real go at total conversion.

Thanks, I knew they had doors, and just assumed they also had discs.

[rodent279]

41 minutes ago, HGR said:

No, not independently switched on any classes that I am aware of. There was only one 'train classification lights' switch in each cab.

 

For disks, all four lamps would be turned on together if any disk flaps were to be open. If all flaps were closed, you could leave the switch 'off'. As you would also do for an intermediate or rear-facing cab - should have all disks closed. With the train classification lights switched 'on', any closed disk flap would obscure its corresponding lamp and not be visible. You might notice light leakage around the edge of the closed disk on night-time long exposure photographs.

 

On headcode locos in most cases there were two bulbs behind each character position. As most locos had duplicated lighting circuits, one bulb in each position would be fed from the No.1 lighting circuit, and the other bulb in each position on the No.2 circuit. That way if one of the circuits tripped out, half-lighting would still obtain.

 

The same duplication occurs with the red tail lights. One is fed by each of the two lighting circuits, but operated by the same one switch. So one circuit trip would allow the other tail lamp to still function.

 

When headcode boxes were fitted with circular opaque white disks to act as marker lights, there were two bulbs roughly behind each marker - bulbs 2+3 and 6+7, so usefully still one of each on No.1 lights and the other on No.2, the other four bulbs becoming handy 'spares'. The switch now being used for marker lights usually was still labelled 'train classification' on locos that previously had disks or headcodes.

 

That explains why you'd sometimes see a domino headcode box with one dot brighter than the other. Did the same apply when headcode boxes were replaced with panels with 2 marker lights in them?

[rodent279]

44 minutes ago, HGR said:

No, not independently switched on any classes that I am aware of. There was only one 'train classification lights' switch in each cab.

 

For disks, all four lamps would be turned on together if any disk flaps were to be open. If all flaps were closed, you could leave the switch 'off'. As you would also do for an intermediate or rear-facing cab - should have all disks closed. With the train classification lights switched 'on', any closed disk flap would obscure its corresponding lamp and not be visible. You might notice light leakage around the edge of the closed disk on night-time long exposure photographs.

 

On headcode locos in most cases there were two bulbs behind each character position. As most locos had duplicated lighting circuits, one bulb in each position would be fed from the No.1 lighting circuit, and the other bulb in each position on the No.2 circuit. That way if one of the circuits tripped out, half-lighting would still obtain.

 

The same duplication occurs with the red tail lights. One is fed by each of the two lighting circuits, but operated by the same one switch. So one circuit trip would allow the other tail lamp to still function.

 

When headcode boxes were fitted with circular opaque white disks to act as marker lights, there were two bulbs roughly behind each marker - bulbs 2+3 and 6+7, so usefully still one of each on No.1 lights and the other on No.2, the other four bulbs becoming handy 'spares'. The switch now being used for marker lights usually was still labelled 'train classification' on locos that previously had disks or headcodes.

 

I shall keep an eye out for that next time I visit a preserved line- I guess I'd make myself really unpopular with traincrew if I pointed out they'd left the rear cab discs open!

[Michael Hodgson]

12 hours ago, F2Andy said:

Why were locos with discs never converted to headcodes? 

Not really much point.  Headlamp codes (including discs, GWR number boards etc) were important when signalmen at busy boxes had to be able to identify approaching trains to prioritise and route them correctly.  With more modern signalling using train describers etc, the reporting number was what you wanted.  If you were in a large signalling centre you were looking at the panel or a computer screen rather than out of the window, so the headcode became unimportant. 

 

The move from discs to 4-character headcodes was an interim stage when there were still some conventional signalboxes that needed something, but now the remaining mechanical boxes are the less important places that can manage without needing to see the front of the train to work out what it is. 

[Mick Boyd]

In reply to HGR's post,

'No, not independently switched on any classes that I am aware of. There was only one 'train classification lights' switch in each cab.

 

For disks, all four lamps would be turned on together if any disk flaps were to be open. If all flaps were closed, you could leave the switch 'off'. As you would also do for an intermediate or rear-facing cab - should have all disks closed. With the train classification lights switched 'on', any closed disk flap would obscure its corresponding lamp and not be visible. You might notice light leakage around the edge of the closed disk on night-time long exposure photographs'.

 

During my 40 odd years footplate experience as far as I'm concerned the lamps on disc fitted locos were turned on independently, certainly on 20's, 24's, 31's, 40's and 44's.

 

Regards, Mick.

[The Stationmaster]

14 hours ago, rodent279 said:

A slightly different slant on the original question is when is the latest that headcode discs would be required to be used, as opposed to train crew messing about with them for fun? Would a blue TOPS numbered diesel ever have been required to use discs to display a headcode for a train?

 

Edit:-a quick trawl through Flickr seems to indicate that headcode discs were still largely being used, where fitted, to indicate the class of train up to around 1975-6. After that they could still be seen, but not necessarily in accordance with the train, class 1 headcode on ballast trains for example.

As noted above - definitely no later than early December 1976.  I am reasonably sure that it was well prior to that date  but the amendment to the General Appendix wasn't made until December 1976.

 

10 hours ago, The Johnster said:

 

To be pendantic, not discs but GW/WR type 3-character train reporting number frames.

 

To be accurately pedantic. D800 -D812 were all delivered with a full set of headcode discs and a frame for WR style 3 digit train numbers.  D813 onwards had 4 character headcode displays and the earlier build locos were gradually brought into line.

 

Edited May 29, 2021 by The Stationmaster

[HGR]

7 hours ago, Mick Boyd said:

In reply to HGR's post,

'No, not independently switched on any classes that I am aware of. There was only one 'train classification lights' switch in each cab.

 

For disks, all four lamps would be turned on together if any disk flaps were to be open. If all flaps were closed, you could leave the switch 'off'. As you would also do for an intermediate or rear-facing cab - should have all disks closed. With the train classification lights switched 'on', any closed disk flap would obscure its corresponding lamp and not be visible. You might notice light leakage around the edge of the closed disk on night-time long exposure photographs'.

 

During my 40 odd years footplate experience as far as I'm concerned the lamps on disc fitted locos were turned on independently, certainly on 20's, 24's, 31's, 40's and 44's.

 

Regards, Mick.

Where were the switches located - were they on the backs of the individual lamp casings (e.g. as on cl.08) or was there a panel for them on the secondman's side next to the boiler controls ? I'm wondering if what I remember had been modified since the disks were out-of-use by then ?