Southern Atlantic

[itsbluesteel]

Hello All,


I'm hoping someone out there will have a good side on image of the Southern Atlantic tender.

Any images or pointers greatly received.


Cheers

Steve

[jma1009]

hi steve,

if you are referring to the LBSCR H1 and H2 Atlantics there is a lot of info online plus some of J.N. Maskelyne's excellent drawings in ME.

the LBSCR B4 tenders were the same and one is being used for the Bluebell Railway's 'new build' 'Beachy Head' project.

have a look at the early pages of the following...

www.bluebell-railway.co.uk/bluebell/locos/atlantic/latest.html

the Bluebell have copies of the original drawings. ive got quite a few outline drawings if they will be of any help to you.

cheers,
julian

[itsbluesteel]

Hello Julian,


Thank you for the info, I will look through the website with interest.






Steve

[mbrown]

There is a new book out about the LBSCR Atlantics - published by Ian Allan and written by Jeremy English, it is called (not surprisingly) "LBSCR Atlantics" and it deals with the March H1 and H2 as well as the various 4-4-2Ts. It has reproductions of the GA drawings of the locos but not the tenders, however there are numerous photos of the Atlantics at all stages of their careers.

The book would be great if you want pictures. Sadly, the author gets into some knots caused, I suspect, by lack of engineering knowledge, claiming that Ivatt's GN Atlantics had air operated reversers and then fantasising about the air being supplied by a special pump.... I think he has misunderstood the concept of the vacuum clutch on the reversing shaft. But that's by the by in terms of the quality of the book's illustrations.

Malcolm

Malcolm

[Deleted]

Mar 27, 2015 21:53:01 GMT mbrown said:

Sadly, the author gets into some knots caused, I suspect, by lack of engineering knowledge, claiming that Ivatt's GN Atlantics had air operated reversers and then fantasising about the air being supplied by a special pump.... I think he has misunderstood the concept of the vacuum clutch on the reversing shaft.

Is that not the case then with the Ivatt ones? The LBSC ones definitely have these air assisted reversers and air pumps as the new build Beachy Head will have them. I have never heard of a vacuum clutch on a reversing shaft either, a steam one yes.

I would be interested to know more about these vac ones.

Cheers
Ben

[mbrown]

The big Ivatt Atlantics had lever reverse - and the route between the lever and the weigh-shaft involved quite a lot of pin joints and rocker arms etc., so they must have been a pig to reverse - Dick Hardy and others explained that is why drivers tended to notch up to a running position and then drive on the regulator. According to the RCTS series of loco histories, the big Atlantics were originally very hard to notch up at all when running (I imagine the weight of the motion thrashing around and the heaviness of the lever was more than the average driver's strength could handle) so they were fitted with a vacuum clutch working on the weigh-shaft to grip it and help control the movement. It's an easy enough thing to arrange - once you've got vacuum for the brakes, you can use it to actuate a small cylinder for the clutch. The Gresley Pacifics (and probably the Thompson and Peppercorn ones too) had the same arrangement, operated by a small lever just below the reverser handle.

One reason why Marsh lengthened the Brighton Atlantics toward the rear was to accommodate screw reverse and the Brighton arrangement of compressed air assistance. This would have been much easier to operate than the GNR lever reverse as the air helped move the valve gear into forward or back gear taking a lot of the weight off the screw. That's a different proposition from simply using vacuum (or air - it all depends what you've got already for your brake) to hold the weigh-shaft against the forces of the valve gear in motion. Unfortunately the author of the new book on the LBSCR Atlantics mixes up the two very different mechanisms.

The small GNR Atlantics (the Klondykes) had screw reverse for the beginning, but the wide firebox of the big Atlantics didn't leave room for that.

Malcolm