| Highland Railway Clan class | |
| Powertype: | Steam |
| Designer: | Christopher Cumming |
| Builder: | R. & W. Hawthorn, Leslie and Company |
| Serialnumber: | 3329–3332, 3443–3446 |
| Builddate: | 1919 (4), 1921 (4) |
| Totalproduction: | 8 |
| Whytetype: | 4-6-0 |
| Uicclass: | 2′C h2 |
| Leadingdiameter: | 3feet |
| Driverdiameter: | 6feet |
| Locoweight: | 63.25LT |
| Tenderweight: | 42LT |
| Boiler: | 4feet diameter, with NaN0NaN0 taper |
| Boilerpressure: | 175psi |
| Firearea: | 25.5square feet |
| Totalsurface: | 1467square feet |
| Superheatertype: | Robinson |
| Superheaterarea: | 256square feet |
| Cylindercount: | Two, outside |
| Cylindersize: | 21x |
| Valvegear: | Walschaerts |
| Valvetype: | 100NaN0 piston valves |
| Tractiveeffort: | 23688lbf |
| Operator: | HR → LMS → BR |
| Powerclass: | LMS/BR: 4P |
| Fleetnumbers: | HR: 49, 51–57 LMS: 14762–14769 BR: 54767 |
| Withdrawndate: | 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. The first four were built in 1919, and the remaining four in 1921.
They had 21by cylinders outside with outside Walschaerts valve gear, 6feet driving wheels and a boiler pressured to 175psi. Weight was for the locomotive and 42LT for the tender. Piston valve diameter is given as 10inches (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 evaporative heating surface is given as 1467square feet, plus 256square feet for the Robinson type superheater, and grate area as 25.5square feet.
Early in 1921 Clan Stewart was used for experiments with oil firing. This seems 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 locomotives passed to the London, Midland and Scottish Railway (LMS) in 1923. The LMS classified them '4P'.
Two survived into British Railways (BR) hands in 1948, but only Clan Mackinnon received its BR number. Some of the Clan names were later reapplied to the BR Standard Class 6.
| HR Number | Name | Built | LMS Number | BR number | Withdrawn | Notes | ||
|---|---|---|---|---|---|---|---|---|
| 49 | Clan Campbell | 1919 | 14762 | — | align=left | |||
| 51 | Clan Fraser | 1919 | 14763 | — | align=left | |||
| 52 | Clan Munro | 1919 | 14764 | 54764 | align=left | BR number not applied | ||
| 53 | Clan Stewart | 1919 | 14765 | — | align=left | |||
| 54 | Clan Chattan | 1921 | 14766 | — | align=left | |||
| 55 | Clan Mackinnon | 1921 | 14767 | 54767 | align=left | |||
| 56 | Clan Mackenzie | 1921 | 14768 | — | align=left | |||
| 57 | Clan Cameron | 1921 | 14769 | — | align=left |