Headcode disc positions?

[Izzy]

Recently I have been building a BR class 15 diesel in 2mm, and in trying to finish off the detail bits like headcode discs I discovered in studying various photos, that the headcode discs were often fixed closed, hinged upwards rather than down, so the light was exposed, with a white dot on the disc rear showing.

 

This is a variation on the normally stated positions of fully open or closed downwards which I have not noticed before, and which I now find is visible in shots of other types of diesel loco without headcode boxes. All three positions could be seen together, yet no headcodes seem to exist that I have been able to find, with no mention of this thrid position.

 

Can anyone shed any light on this? Was it about train route rather than train type, and peculiar to the Eastern Region, or more widespread?

 

Thanks

 

Izzy

[Mick Boyd]

Hi Izzy,

 

headcode discs hinged upwards had no operational significance at all, it was just how the engineman decided to put them out of use when not required to display a particular class of train.

 

I don't recall ever seeing any instructions regarding their position when out of use ( but of course there may have been!).

 

Regards, Mick.

[Izzy]

Thanks Mick,

 

That would explain the total lack of information on this that I have been able to discover to date.

 

Actually I have now discovered the cause of the apparent white dot. It's really quite simple, and shows how thick I can be at times! When the bottom half of the disc is fixed upwards then the hole in it to allow the light to shine through when the disc is fully open allows the white of the top half to show through this hole, and it looks just like a white dot.

 

Izzy

Edited June 23, 2013 by Izzy

[johnb]

Thanks Mick,

 

That would explain the total lack of information on this that I have been able to discover to date. However it does pose the question as to why the white dot on the back of the lower flap half existed. I wish I could post a photo to show this, but all those I have seen are either in books I have or are on-line. Could I post a link to such a photo anyone?

 

Izzy

 

 I think that you will find that the "white dot" is in fact the white of the upper half disc showing through the hole for the light in the lower half disc.

 

If you look at this site  http://www.d8233.org.uk/gallery_others.htm on the Class 15s I think that it will become clear.

 

Hope that helps

 

John

[Izzy]

 I think that you will find that the "white dot" is in fact the white of the upper half disc showing through the hole for the light in the lower half disc.

 

If you look at this site  http://www.d8233.org.uk/gallery_others.htm on the Class 15s I think that it will become clear.

 

Hope that helps

 

John

 

Thanks John,

 

I had been looking at those particular galleries after posting, just realised what I was looking at - and edited my post just as you posted!

 

Izzy

[johnb]

We've all done that sort of thing at one time or another. It's one of those "Oh twit!" (or a rough equivalent) moments

 

regards

 

John

[Clive Mortimore]

Recently I have been building a BR class 15 diesel in 2mm, and in trying to finish off the detail bits like headcode discs I discovered in studying various photos, that the headcode discs were often fixed closed, hinged upwards rather than down, so the light was exposed, with a white dot on the disc rear showing.

 

This is a variation on the normally stated positions of fully open or closed downwards which I have not noticed before, and which I now find is visible in shots of other types of diesel loco without headcode boxes. All three positions could be seen together, yet no headcodes seem to exist that I have been able to find, with no mention of this thrid position.

 

Can anyone shed any light on this? Was it about train route rather than train type, and peculiar to the Eastern Region, or more widespread?

 

Thanks

 

Izzy

Hi Izzy

 

Some cross London freight routes used three position heacodes.

[Izzy]

Hi Izzy

 

Some cross London freight routes used three position heacodes.

 

Ah. Reviewing all the shots I could find I did rather come to the conclusion initially that it was a Eastern region variation, since I didn't find this practice of fixing the disc flaps upwards to exist in photos of diesels on regions other than this.

 

However, what actually drew my attention to this was some black/white shots of class 15's in the original plain green livery on the website mentioned previously about these diesels. The supposed white dots really stand out in these and is what started this enquiry. The particular shots I was interested in showed these locos on the Walton branch among others, on local passenger trains to Thorpe-le-soken.

 

Izzy

[Ray M]

I have just been through the old bits draw, 

And found these diesel headcode discs.

Now i would thought that the real things would be all one size.

So why have i got 2 model sizes.   Which ones will be right for my class 20s/ 24s/ 40s.

[Gwiwer]

Discs were not all the same size.  Which one goes with which class of loco I am afraid is something I cannot help with; I rely on keeping mine with the original box and marking the little plastic bag with the number.  Brass-etch discs are something I haven't yet used.  

[w124bob]

I think the Roxey ones in the top picture are for SR steam locos, I have some which I fitted to a class 20 in error, they're just to big compared with the Bachmann as supplied discs. On the bases that SLW got there class 24 spot on the supplied discs are quite small . Certainly close to that 4.83mm size. One thing that improves the Baccy one is to take an emery board and file the back to thin them down and then file very slightly the all around the locating spigot so that the disc sits much closer to the body. Heljan discs (cl26) are good straight from the sprue.

In my day as a 2nd man , on class 20's the hinges were almost seized. The only occasions when it became an issue were the odd times we ran a single and all the discs at the nose end were fold down, by '78 the meaning was obsolete so we just set express codes. 

Edited November 1, 2020 by w124bob

[Wickham Green too]

On 23/06/2013 at 17:16, Izzy said:

....... bottom half of the disc is fixed upwards  .........

The question has to be - Why were these things designed so BOTH halves folded when it was only necessary for one to ??!?

[stewartingram]

To gain access to the lamp, eg change a bulb?