Highland Railway Clan Class

Highland Railway Clan class
Type and origin Power type Steam Designer Christopher Cumming Builder Hawthorn Leslie and Company Serial number 3329–3332, 3443–3446 Build date 1919 (4), 1921 (4)
Specifications Configuration: ​  • Whyte 4-6-0  • UIC 2'Ch Gauge 4 ft 8+1⁄2 in (1,435 mm) Tender weight 42 long tons (43 t) Firebox: ​  • Grate area 25.5 sq ft (2.37 m2) Boiler pressure 175 psi (1.21 MPa) Cylinders Two, outside Cylinder size 21 in × 26 in (533 mm × 660 mm) Valve gear Walschaerts Valve type 10 in (254 mm) piston valves
Performance figures Tractive effort 23,688 lbf (105.37 kN)
Career Power class LMS/BR: 4P Number in class 8 Retired 1943–1950 Disposition All scrapped

The Highland Railway's Clan Class was a class of passenger 4-6-0 steam locomotives designed by Christopher Cumming. The design is derived from that of the slightly earlier Clan Goods although the similarity is more visual than real.

They had 21-by-26-inch (533 by 660 mm) cylinders outside with outside Walschaerts valve gear, 6 ft 0 in (1.83 m) driving wheels and a boiler pressured to 175 lbf/in² (1.2 MPa). Weight was 62 tons 5 cwt (63.25 t) for the locomotive and 42 tons (42.7 t) for the tender. Piston valve diameter is given as 10 inches (quite large for the period), but they had the conventional short lap, short travel valves. Bearing in mind that they probably spent a large part of their time slogging uphill or coasting down this was probably not too important.

Total heating surface (including superheater) is given as 1,723 sq ft (160.1 m²) and grate area as 25.5 sq ft (2.37 m²). The first four were built in 1919, and the remaining four in 1921.

HR Number	Name	LMS Number	BR number	Withdrawn	Notes
49	Clan Campbell	14762	—	June 1947
51	Clan Fraser	14763	—	August 1944
52	Clan Munro	14764	54764	February 1948	BR number not applied
53	Clan Stewart	14765	—	February 1945
54	Clan Chattan	14766	—	April 1944
55	Clan Mackinnon	14767	54767	January 1950
56	Clan Mackenzie	14768	—	March 1945
57	Clan Cameron	14769	—	November 1943

Two survived into British Railways hands, but only Clan Mackinnon received its BR number.

Early in 1921 Clan Stewart was used for experiments with oil firing. They seem to have been successful, but was not applied to any other locomotives. Just when Clan Stewart reverted to coal operation does not seem to be recorded.

The LMS classified them '4P'.

The Clan names were later reapplied to the BR standard class 6.

References

• Casserley, H. C. & Johnston, Stuart W. (1974) [1966]. Locomotives at the Grouping 3: London, Midland and Scottish Railway. Shepperton, Surrey: Ian Allan. p. 152. ISBN 0-7110-0554-0.