LNER class K4

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LNER Class K4
The K4 61994 The Great Marquess in LNER colors
The K4 61994 The Great Marquess in LNER colors
Numbering: LNER (until 1945) 3441–3446
LNER (from 1946): 1993–1996, 1998
BR (from 1948): 61993–61996, 61998
Number: 6th
Manufacturer: LNER Doncaster Works
Year of construction (s): 1937-1939
Retirement: 1961
Axis formula : 1'C h3
Gauge : 1435 mm ( standard gauge )
Service mass: 69.5 t
Service mass with tender: 114.4 t
Driving wheel diameter: 1,570 mm
Impeller diameter front: 965 mm
Control type : Walschaerts
Number of cylinders: 3
Cylinder diameter: 470 mm
Piston stroke: 660 mm
Boiler overpressure: 13.8 bar
Grate area: 2.55 m²
Superheater area : 28.8 m²
Evaporation heating surface: 160.9 m²
Tender: 3-axis
Control: Walschaerts

The LNER class K4 steam locomotives of the British railway company London and North Eastern Railway (LNER) were procured between 1937 and 1939. The tender locomotives with the wheel arrangement 1'C ("Mogul") based on a design by LNER chief engineer Sir Nigel Gresley were specially designed for traffic on the winding and incline-rich West Highland Line from Glasgow to Mallaig . With the K4 61994 The Great Marquess , a machine was preserved and is used as an operational museum locomotive.

history

The West Highland Line from Glasgow via Fort William to Mallaig placed high demands on the locomotives used there due to its alignment and the comparatively low permitted axle load . LNER had taken over the route from its predecessor, the North British Railway (NBR) and initially continued to use NBR's 2'B locomotives of what is now the LNER class D34 ("Glens"). The increasing train weights required more and more leader locomotives . The use of the new LNER class K3 was prohibited by the LNER bridge construction engineer after initial tests due to the inadequate load-bearing capacity of various bridges; the K3s were out of the question for the section of the route between Mallaig and Fort William due to their axle load. From 1925 LNER class K2 locomotives were used, which Nigel Gresley, the chief engineer of LNER, had designed at the time of the former Great Northern Railway , another predecessor company of LNER. However, due to their poorly protected driver's cabs, these were not popular with the staff of the West Highland Line, which serves an area with sometimes very rough weather conditions. Even the K2s were soon no longer able to cope with the train weights alone and often had to double-cover the trains.

Nigel Gresley therefore commissioned the LNER workshop in Doncaster in 1935 to derive a design especially suitable for the West Highland Line from the successful K3 class. The final design was available in May 1936, and Doncaster delivered the first machine in January 1937. After extensive test drives, which showed the basic suitability and the required performance, the LNER ordered five more, only slightly modified copies in February 1938, which were delivered from July 1938 to January 1939.

After their delivery, the machines took over the intended services on the West Highland Line with trains of all modes of transport. With their performance on the uphill and winding sections north of Loch Lomond, they mastered all demands, but less so at higher speeds. Edward Thompson , Gresley's successor, had one of the K4s, the locomotive with the number 3445 Maccailin Mor , converted into a prototype for the LNER-Class K1 , a two-cylinder Mogul, designed by him . The other five machines remained in use on their home route. From 1947, however, their use was limited to the section from Fort William to Mallaig, their services on the more important section between Glasgow and Fort William took over the new and more powerful locomotives of the LNER class B1 . After nationalization in 1948 , British Railways also used LMS Class 5 “Black Five” locomotives on the West Highland Line in addition to the B1 . The K4 came to the Eastfield depot near Glasgow and were mainly used in the Central Belt between Glasgow and Edinburgh. From 1959 they were stationed in Thornton (Fife) and mainly pulled freight trains in the local coal area of Fife . In October 1961 four machines were decommissioned, the last one, "The Great Marquess" , remained in service until December 1961.

All six machines received nameplates, with the exception of the first machine they were christened after Scottish nobles and clan chiefs :

technical features

Like almost all of Gresley's designs, the locomotives were given a three-cylinder drive with the type of control system he had developed , in which the slide of the inner cylinder was articulated mechanically by controlling the slide of the outer cylinder. The driving axle was the second coupled axle for all three cylinders . With the exception of the significantly smaller coupling wheels, the K4 largely corresponds to the LNER class K3 , whose cylinders were also used in the K4. Gresley took over the boiler from the K2, the firebox came from the LNER class B17 ("Sandringham-Class").

The leading axle was given a Bissel frame modified according to a patent from Gresley with pendulum springs , which - provided that the track was well maintained - helped the locomotive run very smoothly. At higher speeds, however, there were considerable vibrations and twitching movements, which was particularly noticeable on the sections west of Glasgow along the Firth of Clyde that were suitable for such speeds .

In the first K4, the boiler was originally designed with a pressure of just 12.4 bar. However, the first test drives did not show a sufficient increase in performance compared to the previously used locomotives, even if the K4 was able to move a train of 300 tons to Fort William without a leader locomotive. Therefore the boiler pressure of the K4 was increased to 13.8 bar.

From 1937 onwards, all K4s were retrofitted to be equipped with small snow plows and received brackets on the perimeter and fastening holes in the buffer beam.

Preserved locomotives

One of the six K4s, No. 61994 "The Great Marquess" , was preserved. After being taken out of service in 1962, it was acquired by the Viscount Garnock (since 1985 15th Earl of Lindsay) and thus escaped scrapping. Until the end of steam operations at British Rail, Viscount Garnock used the locomotive on various special trips on the British rail network. After boiler repairs, it was from 1973 on the museum railway Severn Valley Railway , where it could not be used due to the axle load. It was not until 1989 that the locomotive got back into operation and returned to active service with its owner in the driver's cab with a trip on its old home route to Mallaig. In the following years it was used again on various special trips until damage to the drive axle ended its use again at the end of 1997. In 2003 the heirs of the 15th Earl of Lindsay, who died in 1989, sold the machine to John Cameron, a Scottish landowner and railroad manager who also owns the A4 60009 "Union of South Africa" . He had it ready for use again. Since then, the locomotive has been used again in front of special trains on the British route network and on museum railways. It is stationed in Thornton (Fife) .

literature

  • OS Nock: The British Steam Railway Locomotive, Volume 2, 1925-1965 , Ian Allan Ltd., London 1966, pp. 157-158

Web links

Commons : LNER Class K4  - Collection of pictures, videos and audio files

Individual evidence

  1. ↑ Severn Valley Railway Wiki: The Great Marquess , accessed April 20, 2014