LSWR H15 Class - Construction History

Construction History

The H15 class represented Robert Urie's first design for the LSWR. It was created in response to a desperate lack of adequate locomotives in service on the LSWR that could be utilised for heavy freight duties. Reliability was also an issue, with ageing locomotive designs taking their toll on the LSWR's resources.

The resultant design was an outside 2-cylinder locomotive fitted with outside Walschaerts valve gear for ease of maintenance, with all the working parts relatively accessible when compared to previous designs operating on the LSWR system.

Ten locomotives (numbers 482–491) were built new by Eastleigh Works with 180 lbf/in² (1.24 MPa) boilers. They appeared in January to July 1914. Urie was a proponent of superheating, so in order to gain experience and data on performance and fuel economy, four of the locomotives (482–485) were fitted with Schmidt superheaters, four (486–489) with Robinson superheaters, and two (490–491) were built as saturated locomotives. The last two had a lower weight than the first eight.

While the data gained from this small experiment showed the benefits of superheating, neither design of superheater was deemed suitable by Urie, so he designed and patented his own: the Eastleigh superheater, which was subsequently fitted to all members of the H15 class.

An additional locomotive was a rebuild of the 1905-vintage E14 class locomotive, number 335, undertaken in December 1914. This one-locomotive class had been earmarked by Urie's predecessor, Dugald Drummond, for major modifications in the light of poor operational performance. Urie however, instead of modifying it, rebuilt it as the eleventh member of the H15 class.. It was the first locomotive to be fitted with an Eastleigh superheater, but it retained its original boiler pressure of 175 lbf/in² (1.21 MPa).

However, improvements were made to the overall design whilst the locomotive was under production at Eastleigh Works. The earlier class members mounted a lower running plate that was raised above the cylinders for clearance. These locomotives also sported a single, straight splasher above the driving wheels, an embellishment that would feature on Urie's later N15 class. The later production locomotives did not feature this design, with a higher-mounted straight running plate above the driving wheels, a feature that was perpetuated on the later S15 class design by Urie.

A total of 26 locomotives were completed in six batches, including number 335, over a period of twelve years. The first two batches of five in each were constructed in 1914. A further fifteen locomotives were constructed in three consecutive batches during 1924, the final one appearing in January 1925, and these were constructed under the auspices of Richard Maunsell, Urie's successor. Amongst the final batches of the class was another rebuild project concerning five members of the Drummond F13 Class. Maunsell's own batch of ten locomotives were a continuation of the design set out by Urie with number 491.

The class was provided with a 5,000 gallon Drummond 'watercart' eight-wheeled tender design that enabled them to travel on the long distances of the LSWR network which never had water troughs. Further modifications to the class were made by Maunsell during the mid-1930s with the provision of smoke deflectors.