Some very interesting points about the 6 surviving A4 pacific locomotives!
Whatever its fame and history, a locomotive can also be seen as a collection of skilfully designed, manufactured and maintained components. The frames of a locomotive are often considered the source of its identity, with other parts frequently swapped between different locomotives of the same type and sometimes between types. As a result of this rotation and despite the fact there were 35 A4s, there is a remarkable circularity between the six surviving A4s, and three of the surviving A4 boilers.
When steam traction was in daily use on Britain’s railways, parts were frequently swapped as locomotives were overhauled. Stocks of overhauled spares were kept to speed the passage of a locomotive through the workshops, in order to prevent work on a particular component slowing the overhaul of the locomotive as a whole. As a result locomotives frequently carried parts that had been fitted new to other locomotives. Careful inspection…
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