page_title: BL 9.2-inch railway gun
section_title: World War I
hierarchical_section_title: BL 9.2-inch railway gun / History / World War I
caption_attribution_description: Diagram showing right elevation of British BL 9.2 inch Mk X gun on railway mounting Mk III, on railway truck Mk II (straightback truck), World War I.
context_page_description: The British Ordnance BL 9.2 inch gun on truck, railway mounted a variety of surplus 9.2 inch naval guns, together with the custom-designed Mk XIII railway gun, on various railway platforms to provide mobile long-range heavy artillery on the Western Front in World War I. Mk XIII remained in service for British home defence in World War II.
context_section_description: Early in 1915 a variety of surplus Mk III and Mk VI 9.2-inch naval and coast-defence guns were adapted by the Elswick Ordnance Company for mounting on railway trucks for use in France and Belgium. They were mounted on Vavasseur slides, which travelled backwards and upwards to absorb the recoil, on "well-based" trucks, where the base was level with the axles.
  These early mountings allowed 10° of traverse left and right, and moved forward and backwards along curved sections of track for further traversing. They limited elevation to 28° and hence limited maximum range. In March 1916 a modification increased elevation to 35°.
  In June 1916 Elswick produced a more sophisticated turntable mounting with a loading platform, on a "straight-back" truck which mounted the gun much higher. This was lowered to the ground for firing, had outriggers for stability, allowed 360° traverse and elevation to 30°. The more modern Mk X gun was mounted on this design, together with 2 Mk X variants intended for Australian coast defence (Mk XT), 4 Vickers 45-calibre guns (Mk XIV) which were originally intended for a foreign order, and a specially developed 35-calibres railway gun (Mk XIII).
caption: Mk X gun on Mk II "straight-back" truck
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