A1 A3 What's The Difference?

[Road Stone]

I see in a Hornby Railways suppliment that they advertise the Flying Scotsman as an A3 in the train set pack. At the back of the same mag, they advertise the loco only, as an A1.

 

I know very little about these things so just wondered what the difference was?

 

Thanks in advance,

 

Jerry

[Flying Pig]

The LNER Encyclopedia has a useful article: http://www.lner.info/locos/A/a1a3a10.shtml

[gresley]

I see in a Hornby Railways suppliment that they advertise the Flying Scotsman as an A3 in the train set pack. At the back of the same mag, they advertise the loco only, as an A1.

 

I know very little about these things so just wondered what the difference was?

 

Thanks in advance,

 

Jerry

 

Simple answer so that you will begin to understand (you admit that you know very little, so easy steps are best). When the pacific locomotives were first designed by Nigel Gresley of the Great Northern Railway, (later, Sir), they were given boilers with 180 lbs pressure and the valve settings were different. As these were the first locomotives of this type, they were given the Classification A1. Subsequently, when they were "upgraded" by being fitted with boilers having a pressure of 220 lbs, and the valve setting altered, in order to improve performance and reduce water/coal consumption, they were then classified A3. There was at that time an existing Class A2, which were pacific locomotives designed and built by the North Eastern Railway. In 1923, these Railway Companies were amalgamated with others to form the LNER (London North Eastern Railway), and all the locomotives and rolling stock of these companies were absorbed into the newly formed company. When the LNER introduced the more powerful A3 locomotives, they also rebuilt the existing Class A1s to conform to the new A3 Class. Therefore, FLYING SCOTSMAN, which was one of the original A1 Class, was subsequently rebuilt to the A3 Class in terms of better performance. This rebuild took place in 1947. It did however, retain one of its major visible differences until later. In 1954, it was changed from Right Hand Drive to Left Hand Drive. This meant that the major cab controls for the driver were moved to the left hand side of the cab, from which the driver had a better view of signals.

Also, when rebult to Class A3, the boiler was fitted with a steam superheater. Because of its size, special rectangular cover plates had to be fitted, and these were easily visible on each side of the smokebox.

 

Various other changes were made udring the life of the locomotive, but those mentioned above are the most noticeable ones.

 

gresley

[DavidBelcher]

Simple answer so that you will begin to understand (you admit that you know very little, so easy steps are best). When the pacific locomotives were first designed by Nigel Gresley of the Great Northern Railway, (later, Sir), they were given boilers with 180 lbs pressure and the valve settings were different. As these were the first locomotives of this type, they were given the Classification A1. Subsequently, when they were "upgraded" by being fitted with boilers having a pressure of 220 lbs, and the valve setting altered, in order to improve performance and reduce water/coal consumption, they were then classified A3. There was at that time an existing Class A2, which were pacific locomotives designed and built by the North Eastern Railway. In 1923, these Railway Companies were amalgamated with others to form the LNER (London North Eastern Railway), and all the locomotives and rolling stock of these companies were absorbed into the newly formed company. When the LNER introduced the more powerful A3 locomotives, they also rebuilt the existing Class A1s to conform to the new A3 Class. Therefore, FLYING SCOTSMAN, which was one of the original A1 Class, was subsequently rebuilt to the A3 Class in terms of better performance. This rebuild took place in 1947. It did however, retain one of its major visible differences until later. In 1954, it was changed from Right Hand Drive to Left Hand Drive. This meant that the major cab controls for the driver were moved to the left hand side of the cab, from which the driver had a better view of signals.

Also, when rebult to Class A3, the boiler was fitted with a steam superheater. Because of its size, special rectangular cover plates had to be fitted, and these were easily visible on each side of the smokebox.

 

Various other changes were made udring the life of the locomotive, but those mentioned above are the most noticeable ones.

 

gresley

 

Am I also right in thinking that only the A3 boiler had the "banjo" dome, with an orthodox round one being fitted to the A1?

 

David

[Bernard Lamb]

Am I also right in thinking that only the A3 boiler had the "banjo" dome, with an orthodox round one being fitted to the A1?

 

David

 

 

It gets complicated. In general you thing correctly. But not all A3 boilers had "banjo" domes.

Thompson built some A3 boilers with round domes to Diag 94A.

Bernard

[gresley]

Am I also right in thinking that only the A3 boiler had the "banjo" dome, with an orthodox round one being fitted to the A1?

 

David

 

 

David, No this is not so clear cut.

 

The original boilers fitted to the original A1 locos,were included in the Boiler Diagram No 94, (hence the description Boiler Type 94). These boilers all had round domes. Later, between 1927 and 1950, further boilers were built, both for new locomotives and also as replacements for older ones. These were all to the new higher pressure of 220 lbs per sq in. Some were built with round domes and were classed as Type94 HP (high pressure version), whilst those built with banjo domes were classed as 94A. These boilers were interchangeable, and all the A3s carried banjo dome boilers at some time, whereas 2 of the A3s never carried round dome boilers. From 1954, Diagram 107 boilers (used on the A4s), but with reduced pressure were also used on A3 locos. A total of 36 being used at various times. These boilers also had banjo domes.

 

So you see, this is a veritable minefield. The only safe way is to decide whixhn loco you want, and the specific period. Then find suitable photos of the loco at that time.

 

Two examples: 60109 HERMIT had a total of 6 boiler changes during its working life, whilst 60107 ROYAL LANCER had only 2 changes.

 

These changes, coupled to the combination of tender types also used, can become rather complicated.

 

gresley

[DavidBelcher]

It gets complicated. In general you thing correctly. But not all A3 boilers had "banjo" domes.

Thompson built some A3 boilers with round domes to Diag 94A.

Bernard

 

Indeed. I think what I was getting at is that the 180psi boiler never sported the "banjo" whereas some - but not necessarily all - 220psi ones did.

 

David

[Flyingscotsmanfan]

Indeed. I think what I was getting at is that the 180psi boiler never sported the "banjo" whereas some - but not necessarily all - 220psi ones did.

 

David

 

Also anither thing to look out for is the Cab cut out. some are small others are bigger.

[Road Stone]

Okay, thanks for that.

 

The model I have, is an 1998 NRM "special" It depicts the FS in BR Dark Green. I assume this is the A3 version as I think it has the Banjo thingy?

 

It's a nice model, the wheels and rods etc are very fine and a gunmetal colour.

 

Cheers, Jerry

[65243]

And there I was thinking the A1 ran from London to Edinburgh and the A3 from London to Portsmouth.

 

OK - I'll leave now

[gresley]

Okay, thanks for that.

 

The model I have, is an 1998 NRM "special" It depicts the FS in BR Dark Green. I assume this is the A3 version as I think it has the Banjo thingy?

 

It's a nice model, the wheels and rods etc are very fine and a gunmetal colour.

 

Cheers, Jerry

 

I have not seen this particular model, so I can't be sure. The loco was rebuilt from A1 to A3 in 1947. There is a pipe which runs along the side of the boiler next to the hand rail. Which side of the boiler is it on, Left or Right ? Also, don't forget - you may well have a model of the locomotive as preserved, and not as running before withdrawal. The "BR Dark Green" livery appears to be as it was from 1952. However, it was changed from RH to LH drive in 1954, was fitted with a double chimney in 1959, smoke deflectors fitted 1961 and withdrawn in 1963.

 

So you see, there are quite a few details to consider in order to decide just what period this version represents.

 

gresley

[JeremyC]

....................... Also, when rebult to Class A3, the boiler was fitted with a steam superheater. Because of its size, special rectangular cover plates had to be fitted, and these were easily visible on each side of the smokebox. Various other changes were made udring the life of the locomotive, but those mentioned above are the most noticeable ones. gresley

As Gresley says A1/3 differences are a minefield. The A1s were superheated, but the superheaters fitted to the A3s were larger, which meant the header was too wide for the smokebox. To allow it to fit holes were cut in the smokebox . The patches on the smokebox were the cover plates over these. As far as I know the presence / absence of these plates is the easiest way to tell an A3 from an A1. There were also two shapes of 'Banjo Dome' or at least of dome cover [which is what you see] the original type looked like, well a banjo, a round dome with a tail. The later ones were a wedge shape with rounded ends. Earlier engines had short travel valve gear, later converted to long travel gear, which all A3s were built with. This caused one visual difference in the flat raised section of the footplate beside the smokebox. If this raised area completely surrounds the steam pipe it's a long travel valve engine, if it doesn't it has short travel valves. A change to the valve gear did not necessarily mean the engine had been converted to A3. The first engines were built to the GNR loading gauge and had taller cabs, domes and chimneys. All the later ones were built [and the earlier ones modified] to the LNER composite loading gauge which involved lowering these items. As mentioned engines could be left or right had drive [latterly they were all LH] The pipe along the side of the boiler [for the brake ejector] is on the drivers side, the reversing rod below the foot plate should be on the same side. Following the appearance of the Thompson A1 all the remaining Gresley A1s were reclassed as A10. The last engine to be converted to A3 was 'Sir Visto' in 1948 Jeremy

[Road Stone]

I have finally got a pix of the loco I mentioned.

 

 

 

It has that Bango thing and a double chimney, so I guess it's the later A3 type also allowing for the BR colours. That is of course assuming Hornby have put the right body on!!

 

Cheers, Jerry

[gresley]

I have finally got a pix of the loco I mentioned.

 

 

 

It has that Bango thing and a double chimney, so I guess it's the later A3 type also allowing for the BR colours. That is of course assuming Hornby have put the right body on!!

 

Cheers, Jerry

 

From the details on the photo, I would say that it represents the loco during the period 1959 - 1961. 1959 it was fitted with a double chimney, and 1961 it was fitted with smoke deflectors.

 

gresley