LSWR 46 Class - Construction History

Construction History

The 46 Class was designed as a response to the requirements of the LSWR to have a range of newer, more reliable locomotives for use on their network. As a result, Adams intended the 46 Class to be an immediate stop-gap measure that could be utilised on passenger services while he devised a better solution to the railway's motive power problem. This solution would eventually prove to be the 415 Class of 4-4-2 locomotive.

The construction of the 46 Class was contracted out by the LSWR in order to speed construction and delivery. The contractor selected was Beyer, Peacock and Company, which manufactured 12 4-4-0 tank locomotives in 1879. After only four years in service, the entire class was eventually converted to the 4-4-2 'radial' tank design between 1883 and 1886, following the successful introduction of the '415' Class in 1882 on London's suburban network.

The reasoning behind the conversion was one of standardization, as various parts could be exchanged between both classes, and in consequence, the only glaringly obvious difference between the two classes, apart from the large side tanks on the 46 class, was the positioning of the safety valves on the boiler. However, the conversion resulted in a heavier locomotive, as an increase in water capacity was incorporated, as was an extended coal bunker to enable longer journeys to be achieved. This entailed the extension of the locomotive's frames, resulting in a longer locomotive than the original 4-4-0 design.