The Collaborative International Dictionary
Trunnion plate
Trunnion \Trun"nion\, n. [OF. trognon the stock, stump, or truck of a tree, F. trognon a core, stalk, fr. tron a trunk, stem. Cf. Trunk.]
(Gun.) A cylindrical projection on each side of a piece, whether gun, mortar, or howitzer, serving to support it on the cheeks of the carriage. See Illust. of Cannon.
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(Steam Engine) A gudgeon on each side of an oscillating steam cylinder, to support it. It is usually tubular, to convey steam.
Trunnion plate (Gun.), a plate in the carriage of a gun, mortar, or howitzer, which covers the upper part of the cheek, and forms a bearing under the trunnion.
Trunnion ring (Gun.), a ring on a cannon next before the trunnions. [R.]