Trunnion

- plates, are two plates in travelling carriages, mortars, and howitzers, which cover the upper parts of the side-pieces, and go under the trunnions. The French have made improvements on this article; they have two pair of trunnion plates; one pair, in which the gun is placed for action; the gun is removed into the other for travelling; and are so denominated. See Am. Mil. Lib.