N7/3 Cab cut out

[boeing757]

Hi,
I have studied the cab of the N7 for what seems like forever but cannot make out if the cut out beading goes across the top of the aperture or ends at each top corner. I am correcting a 7mm model which is obviously wrong but can’t decide what the arrangement is on the full size.
Anyone able to throw any light?
Thank you
Bob

[jwealleans]

Morning Bob,

Best photo I found was this one: https://docbrown.info/docspics/ArchiveS ... o69621.htm

I think the beading stops at the point of disappearing behind the roof. Short of climbing on the preserved one (which I know isn't that easy for you), I think that's as good as you're going to get.

Anyone on here involved with the restoration/maintenance of the real thing?

[Hatfield Shed]

My opinion, from photographs.
The cab side sheet beading appears continuous, terminating when the upper quadrants are complete, and there is a bead on the roof edge which 'fills the gap' between the two side sheet beadings.

I believe this makes sense constructionally as the front and rear side sheets of the cab terminate under the roof edge. Sighting along the roof edge it is higher over the cab opening between the two top quadrants of side sheet beading and a beading is formed on the roof edge.

(I checked that all the photos were notionally of N7/3 by BR running number and date, but given what works could and would do...)

[boeing757]

Thank you both for your replies.
Alas, unless I have misunderstood them they are contradictory.
My own take is that the beading is continuous, and that the steel roof is cut away to clear this. There also seems to be a small rain strip on the roof above the door, as well as the main curved strip.
Unfortunately as Jonathan says, my access to the remaining loco is difficult.
There’s no real hurry as the loco in question has been built with a mix of features needing correction. Just a few:
Cab window vertical movement but rear windows circular.
Rear windows circular but low/straight backed bunker.
My plan is to make an N7/3 out of this hybrid. It’s beautifully finished (not by me) and runs like cats p… off velvet so it will eventually make a lovely loco.
A final plea, can anyone look at 69621 and settle the issue?
Heartfelt thanks as ever.
Bob

[65447]

Work your way through the images on this site - might be more informative: https://preservedbritishsteamlocomotive ... -br-69621/

[65447]

I have a high-resolution image of Liverpool Steet West Side Pilot 69614 that I cannot share for copyright reasons, but it is clear that the beading terminates at the ends of the 90deg curve of the side sheet where it tucks under the roof. That beading does not continue under the roof.

This confirms Hatfield Shed's observations.

[boeing757]

That sounds fairly definitive. Thank you very much. I now need to figure out how to best alter the incorrect door aperture and all the other faults present.
Thanks to all for your help.
Bob

[john coffin]

Looking carefully at Vol 27 of Yeadon, it is clear that the beading on the sidesheets ends at the end of
the curve of the cut out. What may be less clear is that there is a piece of non 90 degree angle iron
along the whole cab length which allows roof to be connected to sidesheets.
It too is cut back vertically over the "cut outs". The rivets are clearly visible on many of the steel rooved cabs.

HTH
Paul

[boeing757]

Thank you Paul,
I have vol27 and have carefully looked at the relevant pics but for me it’s far from obvious. However, looking at the wooden roofed examples it does seem the beading probably does not cross the aperture. My next dilemma is is there a thin rain strip running along the steel roof edge above the door?
I wish I could go and check 69621 but alas I’m 2000 miles away.
Thanks for your help
Bob

[john coffin]

Hi mate, I guess it depends on what you think you are looking for
However, there are some useful photos here
https://docbrown.info/docspics/ArchiveS ... o69621.htm

https://www.youtube.com/watch?v=CXRy_1xJx7c

hope that brings you nearer to where you want to be.

Paul

[boeing757]

Thank you for that Paul.
What a fantastic set of pics in the first link and second contained some excellent footage. I shall come back to both frequently in the future.
In the footage of 69621 in the workshop, I think I can discern a thin strip running across the door at the top. Is this the angle referred to earlier.
Thanks again

[john coffin]

No Problem,

Engineering practice of the time suggests that there would have been some kind of connection
between front and rear part of the cut out, just to ensure it was held together.

People forget that the metal used on most period locos was a lot thinner than we model.
For instance 1/4 or 3/8 thick only and without stiffening, it would have flapped like the devil.

Paul

[65447]

Or you could purchase (as a download) the John Gardner drawings from the GERS website: http://www.gersociety.org.uk/index.php/ ... -tank-loco

The third drawing in the set has the dimensioned details of the steel roof amongst other components.

Incidentally, class N7/3 refers to the Doncaster-built locomotives, 69621 was originally N7/GE and after rebuilding with round-top firebox/boiler N7/4.

You have already highlighted the differences/discrepancies in terms of cabside, front and rear spectacle plate windows, some bunker details and so on, but there were also differences in the coupling rods, and the earlier rear carrying wheels were radial whilst the later ones were pony trucks, and of a slightly different diameter.

[boeing757]

Hi
Thank you,
I have the set of Gardner drawings on dvd. Whilst I have not studied them particularly carefully, I could not, on perusal, find any details clarifying my enquiry regarding cab door beading. I will check again when I get home from a short vacation.
Yes I am aware of the various classifications for N7s but with the total elimination of the species apart from 69621 that seemed like the best place to start as it’s possible someone reading this might just be able to take a look. I believe all the door apertures are the same.
My loco also has the correct coupling rods and whether the rear wheels are radial or pony truck mounted is beyond the level of authenticity I need.
Thanks for your insight.
Bob

[65447]

Bob,

Below is an extract from the photo of 69614. This loco was built in the same batch as 69621, so should be representative. Make of it what you will...

69614 cab side sheet and roof detail.jpg (26.42 KiB) Viewed 4829 times