page_title: Glossary of British ordnance terms
section_title: Hydro-pneumatic
hierarchical_section_title: Glossary of British ordnance terms / Recuperator / Hydro-pneumatic
caption_attribution_description: English: Diagrams showing recoil cylinder, recuperator and intensifier, of CP Mk XVIII mounting for British QF 4-inch Mk IX naval gun.
context_page_description: The terms may have slightly different meanings in the military of other countries.
context_section_description: When World War I began, both the army and navy were in the process of introducing a "hydro-pneumatic" recoil system in which the recuperators were driven by air compression rather than springs. Examples were the navy's new QF 4 inch Mk V gun and the army's new BL 9.2 inch howitzer.
  The unexpectedly heavy rates of fire experienced (mainly on the Western front) early in World War I caused many spring breakages in the 1904 generation field artillery (including in the Mk I 60 pounders at Gallipoli) and led to field modification of the 18 pounder which replaced the springs in the housing above the barrel with a pneumatic unit. By the end of the war the hydro-pneumatic system had become standard for a new generation of field artillery, typically seen in a box-shaped unit below the barrel in the 18 pounder Mk IV, 60 pounder Mk II, 6-inch and 8-inch howitzers and 6 inch Mk 19 gun.
caption: Pneumatic recuperator and hydraulic recoil cylinder arrangement of QF 4.7 inch naval gun, World War II
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