Prior to the Grouping, the Caledonian Railway had designed a 2-6-0 mixed traffic engine, which George Hughes decided had potential for use by the LMS. However, the restrictive loading gauge of the former Midland lines meant that inclining the cylinders was a necessity and the final design had extremely inclined cylinders which coupled with a raised running plate at the front end, made the locomotive somewhat distinctive. Hughes decided on a parallel Belpaire boiler for the locomotive pressurised to no more than 180 lb per sq inch, which meant that the cylinders had dimensions of 21 inches diameter by 26 inches of stroke, using long lap Walschaerts valve gear. This arrangement would result in the nickname "Land Crabs" or just "Crabs".

Technical Data
 
Introduced : 1926
Number built : 245
Wheel arrangement : 2-6-0 "Mogul"
 
 
Glossary
 
Mixed Traffic engine : a locomotive that is intended to haul both passenger and freight trains.  

Class 5F "Crab"

Hughes retired before the locomotives were finished, and the designs ended up with Fowler, who promptly proceeded to apply Derby engineering principles to the design, somewhat to the detriment of the original Horwich design. The boiler design was retained, only because it was too late to get a standard Derby boiler onto the engine, but a lot of the other parts became pure Derby. Worst of all, the locomotives were given standard Derby tenders which were narrower than the locomotive, spoiling the lines of the original design. These tenders were to remain with the locomotives throughout their working lives.

Although intended as a freight engine, the "Crabs" unofficially became a mixed traffic engine, so could occasionally be found on passenger services. By the end of their career, British Railway officially recognised them as such, giving them the power classification of 5P5F. They were considered to be a successful design and were the only non-Derby inspired design of the Fowler era.

The class was renumbered in 1934 to become numbers 2700-2944, with 40000 being added to these numbers upon nationalisation.

Preservation

Three examples are preserved; numbers 2700 (A static exhibit at the National Railway Museum, and currently being reliveried into LMS Crimson as 13000), (4)2765 (currently running on the East Lancashire Railway in LMS Crimson as 13065) & 2859 (Stored at RAF Binbrook in Lincolnshire, its current fate is uncertain as it is the subject of a legal dispute and it appears that some parts may have been scrapped).  

Class 5F No 42765 at Kidderminster station, Severn Valley Railway, September 2001

Original Number

Location of building

Year of Building

13000-13006

Horwich

1926

13007-13029

Horwich

1927

13030-13035

Crewe

1926

13036-13099

Crewe

1927

13100-13107

Crewe

1928

13108-13109

Crewe

1929

13110-13129

Horwich

1929

13130-13149

Horwich

1930

13150-13224

Crewe

1930

13225-13234

Crewe

1931

13235-13244

Crewe

1932

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