The Ivatt Class D1 4-4-0 Locomotives
These were Ivatt's final 4-4-0 class, and were built in 1911. Similar to the "1321" Class (LNER D2), the D1s differed with the fitting of Schmidt superheaters and piston valves. The cylinder diameter was also increased by one inch. In order to clear the cylinders, the boiler was pitched higher and the bogie was moved further forward. One batch of fifteen locomotives were built, and were classified with the "1321" locomotives as Class D1 by the Great Northern Railway (GNR). The LNER split the class, with the "1321" locomotives being reclassified as D2. With the advent of the Atlantics (LNER C1 and (LNER C2), the GNR had limited need for further 4-4-0s and the D1 represented the ultimate development of the GNR 4-4-0 design.
These were the only 4-4-0s that Doncaster built new with superheaters. 18-element Schmidt superheaters were fitted with three rows of six elements. The basic boiler was the Diagram 7, also fitted to the D2, J2, J5, J6, N1, and N2 locomotives. This was a telescopic design with the unusual feature of having the wider barrel at the smokebox end. Replacement boilers after 1912 were built as one long 4ft 8in diameter barrel. Nos. 60 and 61 were the first GNR locomotives to be built with Ross pop safety valves. With the various boiler swaps between types, many of the D1s were fitted with both Ross and Ramsbottom safety valves at different times.
The cylinders and steam chests were lubricated by a Wakefield mechanical lubricator positioned on the right-hand side of the running plate. Siphon lubricators lubricated the coupled wheel axleboxes.
Although they were not intended for main line expresses, the D1s were initially used on some of the GNR's heaviest main line duties, including the Grantham-York and Doncaster-Leeds sections. After World War 1, the D1s were replaced on their heaviest Leeds duties by Gresley 2-6-0s. The allocation at Grouping (1923) was Cambridge (No. 56), New England (Nos. 63-5), Grantham (Nos. 57-62), and Leeds (Nos. 51-5).
In 1925, the GN section declared the D1s as surplus to requirements and they were all moved to the Scottish section. For the move, they were cut down to the North British (NBR) loading gauge and Westinghouse pumps were fitted. To fit the loading gauge, short chimneys and dome covers were fitted, and the whistle stand was cut down. In Scotland they replaced a variety of NBR 4-4-0s including the D31s. The Scottish duties mainly consisted of local passenger services and piloting main line expresses. The Fife D1s were employed mainly on ballast trains. The D1s were always unpopular with the NBR crews, and were regarded as cast-offs from the GN section. NBR crews quickly gave them the nickname of "ponies". The D1s were also found to be rough riders with uncomfortable and draughty cabs. Various mechanical and steaming difficulties were found, and they experienced both erratic running and poor maintenance. This was probably a vicious circle, and it is difficult to tell if the poor running was due to the maintenance or vice versa. It is notable that unlike most other Scottish types, the D1s never had regular rosters.
Between 1930 and 1932, seven D1s would return south and operated on the Great Eastern (GE) section and on the Midland & Great Northern (M&GN) Joint Line. These were converted to Robinson superheaters from 1932-34. One of the D1s that stayed in Scotland may have also been converted, but records are unclear.
The first five D1s were withdrawn in 1946. The last D1 was withdrawn in November 1950.
|Piston Valves:||8in diameter|
|Boiler:||Max. Diameter:||4ft 8in|
|Heating Surface:||Total:||1129 sq.ft.|
|Superheater:||192 sq.ft. (18x1.25in)|
|Tubes:||562 sq.ft. (118x 1.75in)|
|Flues:||257 sq.ft. (18x 5.25in)|
|Grate Area:||19 sq.ft.|
|Tractive Effort:||16,074lb||(@ 85% boiler pressure)|
|Weight (full):||Total:||96 tons 8cwt|
|Engine:||53 tons 6cwt|
|Tender:||43 tons 2cwt|
|Max. Axle Load:||18 tons 0cwt|
The last D1 was withdrawn in 1950, and none survived into preservation.
A tinplate O gauge model thought to date from the 1930s operates at the Brighton Toy and Model Museum.
Thank you to Mike Morant Collection for the colour illustration of D1 No. 65.