TRUNNION
Etymology
Noun
trunnion (plural trunnions)
One of the short stubby bearings on either side of a cannon; a gudgeon.
A similar rotational bearing comprising a rotating arc or ring sliding in the groove of a stationary arc, used in machinery to allow a workpiece to be moved relative to a fixed tool.
A similar rotational bearing used in automotive suspensions.
Source: Wiktionary
Trun"nion, n. Etym: [OF. trognon the stock, stump, or truck of a
tree, F. trognon a core, stalk, fr.tron a trunk, stem. Cf. Trunk.]
1. (Gun.)
Definition: 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.
2. (Steam Engine)
Definition: 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.]
Source: Webster’s Unabridged Dictionary 1913 Edition