The

Caledonian Railway The Caledonian Railway (CR) was a major Scottish railway company. It was formed in the early 19th century with the objective of forming a link between English railways and Glasgow. It progressively extended its network and reached Edinburgh an ...

191 Class were

4-6-0 A 4-6-0 steam locomotive, under the Whyte notation for the classification of steam locomotives by wheel arrangement, has four leading wheels on two axles in a leading bogie and six powered and coupled driving wheels on three axles with the abse ...

passenger engines designed by

William Pickersgill William Pickersgill (1861 – 2 May 1928) was an English railway engineer, and was chief mechanical engineer of the Caledonian Railway from 1914 until Grouping in 1923. He was appointed locomotive superintendent of the Northern Division of t ...

and built in 1922 by the

North British Locomotive Company The North British Locomotive Company (NBL, NB Loco or North British) was created in 1903 through the merger of three Glasgow locomotive manufacturing companies; Sharp, Stewart and Company (Atlas Works), Neilson, Reid and Company (Hyde Park Wor ...

. The class was intended for use on the Callander and Oban line, to augment the 55 Class 4-6-0s and replace elderly 179 Class 4-4-0s, and they were thus known as the New Oban Bogies, however, they were also used on other Caledonian lines.

Reputation

The locomotives were not completely successful, having a reputation for being short of steam unless skilfully fired, and the dubious distinction of the highest total locomotive hammerblow of any locomotive class inherited by the LMS upon its formation in 1923. The lack of

superheating In thermodynamics, superheating (sometimes referred to as boiling retardation, or boiling delay) is the phenomenon in which a liquid is heated to a temperature higher than its boiling point, without boiling. This is a so-called ''metastable state ...

was a curious omission from a type introduced as late as 1922. This may not have helped their steaming problems.

Disposal

All were withdrawn and scrapped between 1939 and 1945, having been displaced by new Black Five 4-6-0s under the LMS's drive for standardisation.

References

* 191 4-6-0 locomotives NBL locomotives Railway locomotives introduced in 1922 Scrapped locomotives {{Scotland-steam-loco-stub