Harry

Harry is a SECR K and SR K1 class!

## Technical Details:

The 2-6-4 wheel arrangement was not in common use in Great Britain at this time, as many railway companies operated routes that required locomotives with greater fuel capacity, or short branch lines that necessitated smaller locomotives. The 2-6-4 tank engine design had only been used once before for standard gauge locomotives in Britain, on the Great Central Railway's 1B class freight locomotives of 1914. However, the configuration was ideal for the SECR, because of its shorter mainlines, and allowed for a long wheelbase with a leading axle to permit greater stability at speed on track curves. The tightness of the curves on the former LCDR mainlines had constrained the size of locomotives operating on the SECR, as they had been hastily erected during the nineteenth century to compete with those of the South Eastern Railway (SER). The longer locomotive could also accommodate a larger boiler than a 4-4-0, giving sufficient power to avoid double-heading of locomotives on heavier trains.

The K class design used a "Bissel bogie" leading axle and a plain trailing bogie. The trailing bogie permitted the use of a large coal bunker that was capable of sustaining the locomotive over the run between London Charing Cross and Dover Marine, and side water tanks of 2,000 imp gal (9,100 l; 2,400 US gal) capacity were used, negating the need for a tender. The coupled wheelbase between the rear and centre driving wheels was reduced from that used on the mechanically identical N class to 7 ft 9 in (2.362 m) to accommodate the bogie. The cab was fully enclosed, although the set of four small front spectacle plates (the windows on the front face of the cab for forward visibility) were the same as those used on the N class.

The K class was designed by Maunsell's team in 1914 as part of his proposed standardisation programme following the N class, but the designs were not shown to the railway directors until early 1915 to enable all six designs to be shown at once. The design incorporated the principles of power and reliability established by George Churchward, using a Belpaire firebox that sloped downwards towards the cab instead of a round-topped version, a regulator located in the smokebox, long-travel valves for free running at high speeds, a sharply tapered and domeless boiler, and a right-hand driving position. The inclusion of these features is attributed to Holcroft, Maunsell's personal assistant, who had worked on the GWR 4300 class and the N class. James Clayton, Maunsell's Chief Locomotive Draughtsman, brought simpler and more functional Midland Railway influences to the design, such as the shape of the cab and the drumhead-type smokebox, which sat on a saddle that was of wider diameter than the fully lagged and clad boiler. The latter was fitted with Ross pop safety valves and pressed to 200 psi (1.38 MPa).

Other innovations by Maunsell's team included greater superheating surface area, locating the boiler water top feed inside a dome-like cover with external clackboxes and water feed pipes mounted on either side, outside Walschaerts valve gear, and parts that could be shared with similar locomotive classes to reduce maintenance costs. The firebox was narrower towards the rear and featured a continuously sloping grate, whilst the ashpan was fitted with front and rear damper doors, the latter adjusted to clear the rear driving axle. The lower part of the coal bunker incorporated a water tank of 760 imp gal (3,500 l; 910 US gal) capacity. This was connected to two 620 imp gal (2,800 l; 740 US gal) side tanks by two rectangular pipes on either side of the locomotive that also formed supports for the cab footplate.

### K class

In January 1915 Maunsell received authority to build six examples, but, as with the N class, production was delayed due to the use of the Ashford works for wartime armaments manufacture. Assembly began in 1917 and the first, No. 790, emerged in July of that year. It was based at Bricklayers Arms depot, preceding the earlier N class design into service by one month. Further construction was deferred until after Ashford had caught up with the maintenance backlog caused by the war.

Ten more locomotives were ordered by the SECR from Ashford works in June 1920, and to speed delivery the construction of frames, cylinders and side tanks was subcontracted to the Royal Arsenal at Woolwich. However, further severe delays at Ashford caused by the backlog of repair work meant that the boilers had to be supplied by the North British Locomotive Company. Construction of these locomotives had not begun by 1 January 1923, when the Railways Act 1921 merged the SECR with other railways in southern England to form the Southern Railway.

Maunsell was appointed CME of the newly formed Southern Railway in 1923, and inherited the 1920 SECR order for ten K class locomotives. The order was still outstanding in 1924, although most of the component parts had been made. On 14 January 1925, Maunsell ordered No. 790 to be overhauled and trialled on the Central section. As the locomotive proved suitable for the operating conditions of this section, the Southern Railway's Locomotive Committee proceeded with the assembly of the K class parts using outside contractors. Nine sets of parts (Nos. A791–A799) were conveyed to Armstrong Whitworth for assembly and the finished locomotives delivered in May and June 1925. These were dual-fitted with vacuum and Westinghouse (air) brakes for use with the former London, Brighton and South Coast Railway (LBSCR) rolling stock on the Central section. Other differences from the prototype included the relocation of the regulator to the dome and an increase in superheater area. The tenth set of parts was retained by Ashford and used for the first member of the K1 class later that year.

In May 1925 Maunsell ordered a further ten locomotives from Brighton works (Nos. A800–A809), which only had vacuum brakes for the SECR stock on the Eastern section. They were delivered between July and December 1926. This group had modified suspension on the bogie and leading axle, in an attempt to address complaints from the crews of rough riding experienced with earlier members of the class. A further 20 members of the class were ordered in March 1926 (ten each from Ashford and Brighton works), despite strong reservations expressed by the Operating Department concerning "the wisdom or desirability of placing so many large passenger tanks in service". These were allocated the numbers A610–A629, and work had begun on building the frames and cylinders when the order was cancelled following an accident at Sevenoaks in 1927 involving locomotive No. A800. These numbers were later allocated to the first production batch of U class locomotives.

### K1 class

In August 1919, a proposal was put to the SECR's Locomotive, Carriage and Wagon Committee for 2 and 3-cylinder tank engines of 2-8-0 wheel arrangement for heavy shunting of freight wagons. They were to use the same boiler as the K and N classes and the general layout was similar to designs used by the GWR in South Wales. Nothing came of this proposal because of other commitments and the absorption of the SECR into the Southern Railway. In 1922, Holcroft suggested that 3-cylinder 2-6-0 tender locomotives with 6 ft (1,830 mm) driving wheels should be built instead of tank locomotives. Despite the benefit of a greater operational range, Holcroft's immediate superior, Clayton, refused to pass this suggestion on to Maunsell. The 3-cylinder principle was therefore applied to the K class.

At the Southern Railway's January 1925 Locomotive Committee meeting, when it was decided to use outside contractors to build the K class, Maunsell received authority to retain one set of parts at Ashford works to construct a prototype 3-cylinder 2-6-4 tank. The modification was based upon that used on N class No. 822 to produce a 3-cylinder locomotive in 1922, although it retained the 6 ft (1,830 mm) driving wheels and shorter wheelbase of the K class. The modification was the inclusion of an additional (inside) cylinder between the frames, and a crank axle was fitted to the middle driving wheels. The axle was connected to the inside cylinder assembly by a connecting rod inclined at 1 in 8 to clear the front driving axle. This arrangement was supplemented by two smaller-diameter outside cylinders with 16 in (406 mm) bore (compared to the 19 in (483 mm) cylinders of the K class), and a greater chimney diameter. The resulting prototype 3-cylinder "K1" was narrower than the K class and hence could work on routes with restricted loading gauge. As with No. 822, this locomotive used Holcroft's derivative of the Gresley conjugated valve gear to drive the inside cylinder. To accommodate this, the boiler had to be raised by 3 in (76 mm) above the inside gear, raising the centre of gravity on the locomotive.

The main visual difference between the K and K1 classes was at the front end: the K1 incorporated a vertical metal cover above the front buffer beam to protect the third cylinder and associated Holcroft valve gear assembly from the elements. It also featured a new cab design with redesigned single front spectacle plates, and a pair of substantially constructed steps were fitted behind both outside cylinders to provide access to the running plate. The lack of a middle cylinder on the K class locomotives had allowed the provision of a footplate that curved from the buffers to the water tanks. The K1 prototype emerged from Ashford works as No. A890, and underwent trials from 1 December 1925 before entering regular service. Only one locomotive of the K1 class was built; plans to build a further ten (Nos. A891-A900) alongside a batch of five N1 class 2-6-0s were cancelled after the Sevenoaks accident in August 1927. Following rebuilding as a 2-6-0 tender locomotive in 1928, No. A890 was reclassified U1 and was the forerunner of twenty more basically similar locomotives built in 1931.