IVATT LARGE ATLANTICS

[kudu]

The history of these locos is somewhat complicated, as the item in the "Locomotives" section in this Encyclopedia testifies.

Can anyone confirm that Gresley's 1914 rebuild of no 279 was as a 4-cylinder simple locomotive? I am confused as the table for the C1s quotes 279 as a compound.

I would also like clarification on the valve gear of 279. The Encyclopedia entry says it had Walschaerts, but as a 4-cylinder loco did it have 4 sets or 2?

Next, regarding no 1421, which started life as compound (when was it built?) but was rebuilt "as a standard C1 Atlantic" in 1920 with piston valves. Does this mean it then lost its Walschaerts valve gear in favour of Stephenson, this being the gear on the standard C1s (with piston valves on the last ten)?

Answers welcomed (especially accurate ones).

Kudu

[Atlantic 3279]

According to accounts I have read, including the RCTS books and others dealing with Ivatt / Gresley locos, Atlantics generally, and British Pacifics, also confirmed by photos:

279 was ex works 1915 as a four cylinder simple, probably intended as a trial of a four cylinder front end for the pacific that Gresley may have had in mind at the time. The outside Walschaerts gear also drove the inside valves - there was an extra set of valve crosshead guides in front of the outside steam chests (much like the later standard Gresley three cylinder engines looked) these being connected by levers to the inside valve spindles. It seems that the four cylinders where actually a bit much for 279's boiler when attempting running at full tilt.

I think it safe to assume that 1421 became entirely standard, including inside Stephenson gear. The rebuild was apparently so thorough that it officially counted as being equivalent to a new engine.

[Saint Johnstoun]

I refer students to illustration on P12 of Willie Yeadon V13 which shows 1421 rebuilt to standard but with piston valves and superheater.

251 was put back to as near original in 1947 but retained the superheater boiler. When put back into service it wouldn't steam so a set of dummy superheater elements were added to good effect.

O for a RTR model of one of these beauties.

One wonders what would have happened had Gresley copied the Pennsy and built a super Atlantic?

Watch this space!

[coachmann]

Pennsys Super Atlantics were soon demoted to working local trains, which they did into the 1950s. Britians Atlantics were almost frontline power for many years and some of them could still do a useful job on expresses right to the end. I have in mind the NER Z class engines, which were well thought of right up to their demise in 1947.

I think Atlantics were built in this country because of the extra drag of a 6-coupled wheelbase and because some locomotive designers could not come to terms with 4-6-0 design. But the Great Western considered the extra pair of drivers was more useful as having that extra reserve of adhesion, and once the 4-6-0 design was perfected the Atlantic design hit the buffers.

[Saint Johnstoun]

Howzabout this?

Had Gresley gone for a modernised Atlantic is this what it would have looked like?

[kudu]

Howzabout this?

CXred.JPG

Thanks, but what is it?

Kudu

[kudu]

I refer students to illustration on P12 of Willie Yeadon V13 which shows 1421 rebuilt to standard but with piston valves and superheater.

Is this illustration consistent with Atlantic 3279's "safe assumption" that 1421 had Stephenson's (inside) valve gear?

Kudu

[kudu]

According to accounts I have read, including the RCTS books and others dealing with Ivatt / Gresley locos, Atlantics generally, and British Pacifics, also confirmed by photos:

279 was ex works 1915 as a four cylinder simple, probably intended as a trial of a four cylinder front end for the pacific that Gresley may have had in mind at the time. The outside Walschaerts gear also drove the inside valves - there was an extra set of valve crosshead guides in front of the outside steam chests (much like the later standard Gresley three cylinder engines looked) these being connected by levers to the inside valve spindles. It seems that the four cylinders where actually a bit much for 279's boiler when attempting running at full tilt.

Thanks, Atlantic 3279. The voice of authority, no doubt.

Kudu

[Eightpot]

According to accounts I have read, including the RCTS books and others dealing with Ivatt / Gresley locos, Atlantics generally, and British Pacifics, also confirmed by photos:

279 was ex works 1915 as a four cylinder simple, probably intended as a trial of a four cylinder front end for the pacific that Gresley may have had in mind at the time. The outside Walschaerts gear also drove the inside valves - there was an extra set of valve crosshead guides in front of the outside steam chests (much like the later standard Gresley three cylinder engines looked) these being connected by levers to the inside valve spindles. It seems that the four cylinders where actually a bit much for 279's boiler when attempting running at full tilt.

I think it safe to assume that 1421 became entirely standard, including inside Stephenson gear. The rebuild was apparently so thorough that it officially counted as being equivalent to a new engine.

I think the 'levers' were actually 'rockers' in that for the inside cylinders the valves were underneath.

[kudu]

Howzabout this?

CXred.JPG

Had Gresley gone for a modernised Atlantic is this what it would have looked like?

Pity he never attempted a modernised Single.

Kudu

[hyperion]

With 4 cylinders.


Atlantic279 is as the gentleman with that name says according to RCTS 'GN Loco. History' but I'll quote the last piece on 1421 :-

"- - - it entered Doncaster Works in March 1920 for thorough rebuildinbg as a standard two-cylinder Atlantic and was 'counted as a new engine'. No. 1421 left Works in July so rebuilt and equipped with a Robsinson 24-element superheater and piston-valve cylinders."

I learning a lot meself from this, makes a change from trying to find out the truth behind 'Wylam Dilly' and 'Puffing Billy' and the like.

[hyperion]

Incidentally, I've studied and followed the railway faith for as long as I can remember and so dare hardly ask this question - BUT - what's a 'Pennsy' Atlantic? ? I swear I never heard of such a beast 'til Coachmann's and accompanying comments above.

[Atlantic 3279]

Perhaps my remark about 1421 being rebuilt entirely "as standard" ought to have been accompanied by the additional comment that by 1920 the fitting of a superheater and piston valves was becoming the new standard for the large atlantics.

[Saint Johnstoun]

Gresley was a student of American Locomotive Practice. The Pennsylvania Railroad in the USA had developed its Atlantic (4-4-2) design from meagre beginnings into the Superheated E6A Atlantic of 1914 which used the same boiler as their H8 2-8-0. The later development was the G5s 4-6-0 of 1923.

The E6a was developed into a Pacific Design which culminated in the famous K4s. It was this pacific that Gresley based his original A1 round.

[richard]

That is the standard story about the Pennsy K4, but I'm one of the sceptics.
He probably was following US progress - as he was following Chapelon, talked to Stanier, etc. but I don't think the A1s owed much to the K4.

They were Pacifics. What else did they have in common? A wide firebox/grate. The K4 firebox actually looks more like a BR standard era wide firebox with a sloping grate. Also the Ivatt large boiler Atlantics (LNER C1) had already introduced the wide firebox concept to Britain's railways. In fact, these were first such locos in the UK (beating the Decapod by a matter of weeks). Surely Gresley would have borrowed a wide firebox/grate from the C1s which he would have been intimately familiar with, and not a Pacific on a different continent which he never set his eyes on?

What else makes the A1 different? The valve gear - but this was a Gresley modification (already on his K3 and O2) of a Holcroft design.

Richard