LMS 2 and 2A boilered 4-6-0 locomotives
The London, Midland and Scottish Railway (LMS) 2 and 2A boilered 4-6-0 locomotives were express passenger 4-6-0 steam locomotives. In 1935, William Stanier, Chief Mechanical Engineer of the LMS, ordered the rebuilding of the unique experimental high pressure compound locomotive 6399 Fury. The Schmidt-Henschel boiler was replaced with a tapered boiler, with a drumhead smokebox, designated type 2.[1] The type 2 boiler had a tube surface of 1,669 square feet, formed by tubes 2+1⁄8 inches (54 mm) in diameter and 14 ft 3 in (4.34 m) long.[2] It was fitted with a 28-row superheater with 360 square feet (33 m2) of heating surface.[1] The superheater elements, 1+1⁄8 inches (29 mm) in diameter, were fitted into flue tubes 5+1⁄8 inches (130 mm) diameter.[2]
On testing the boiler performed poorly, with heat transfer to the water being inadequate because the hot gases from the firebox passed too rapidly through the tubes to the smokebox.[1] The rapid passage of gas was indicated by too high a temperature in the smokebox, and the choking of the smokebox by excessive char carried through from the firebox.[2] The boiler was re-tubed with 180 smaller tubes 1+7⁄8 in (48 mm) diameter, and with superheater elements 1+1⁄4 in (32 mm) diameter.[2] The single blastpipe was replaced with a double blastpipe and chimney to provide adequate gas velocity in the smokebox.[1] This, combined with the increased rate of evaporation provided by the re-tubing, improved the performance of the boiler substantially.[2]
The performance of Stanier's Jubilee Class also suffered from incorrect boiler proportions.[2] In 1935, a design for an improved taper boiler was schemed out; this was 13 ft (4.0 m) long, with 198 tubes 1+3⁄4 inches (44 mm) in diameter.[2] In 1943 Stanier instructed Coleman, the chief designer at Derby, to rebuild two of the Jubilee class with boilers to this design.[2] This type of boiler was designated type 2A.[3] Combined with modifications to the steam ports and valve gear, the rebuilding produced locomotives that were more powerful and economical than either the original Jubilees or the Royal Scots.[4]
As the boilers of the Royal Scots were due for replacement, and their built-up smokeboxes were proving difficult to keep airtight, the decision was taken to rebuild the class in batches.[4] They were also fitted with type 2A boilers. Rebuilding started in 1943, and eventually all 70 members of the class were rebuilt.
From 1946, 18 of the 52-strong Patriot Class (which shared the same chassis as the Royal Scots) also received 2A boilers.
List of locomotives
[edit]A total of 91 locomotives were rebuilt. Dates of building and numbers of engines are given in the following table.
| LMS Nos | BR Nos | Class | Rebuild source | Rebuild dates | Rebuilt by LMS | Rebuilt by BR | Total |
|---|---|---|---|---|---|---|---|
| 6170 | 46170 | British Legion | 6399 Fury | 1935 | 1 | 0 | 1 |
| 5735/6 | 45735/6 | Rebuilt Jubilee | Jubilee Class | 1942 | 2 | 0 | 2 |
| 6101/2/5-7/10/13/23-30/4/6/7/40-3/8/51/3/5/6/8/62-5/7 | 46100-69 | Rebuilt Royal Scot | Royal Scot | 1943-1955 | 43 | 27 | 70 |
| 5514/21/6/8-31/40 | 45512/14/21-3/25-32/4-6/45 | Rebuilt Patriot | Patriot | 1946-1949 | 8 | 10 | 18 |
| Total | 1935, 1942–1955 | 54 | 37 | 91 |
Withdrawal
[edit]All 91 locomotives were withdrawn from stock between 1961 and 1965.
| Year | British Legion | Rebuilt Jubilees | Rebuilt Royal Scots | Rebuilt Patriots | Total |
|---|---|---|---|---|---|
| 1961 | 0 | 0 | 0 | 2 | 2 |
| 1962 | 1 | 0 | 29 | 0 | 30 |
| 1963 | 0 | 0 | 15 | 5 | 20 |
| 1964 | 0 | 2 | 21 | 8 | 31 |
| 1965 | 0 | 0 | 5 | 3 | 8 |
| Total | 1 | 2 | 70 | 18 | 91 |
References
[edit]Sources
[edit]- Cox, E.S. (1970). Royal Scots of the LMS. Shepperton: Ian Allan. ISBN 0711001650.
- Pat Rowledge Stanier 4-6-0s of the LMS