from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A pin or gudgeon, especially either of two small cylindrical projections on a cannon forming an axis on which it pivots.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. One of the short stubby bearings on either side of a cannon; a gudgeon.
- n. 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.
from the GNU version of the Collaborative International Dictionary of English
- n. 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.
- n. A gudgeon on each side of an oscillating steam cylinder, to support it. It is usually tubular, to convey steam.
from The Century Dictionary and Cyclopedia
- n. One of the cylindrical projections on the sides of a cannon, cast or forged in one piece with the cannon itself, which support it on its carriage.
- n. In steam-engines, a hollow gudgeon on each side of an oscillating cylinder, which supports the cylinder, and through which steam is received and exhausted.
a point from the end equal to the semi-diameter of the trunnion, which is marked on each branch.
In mortar-vessels other expedients are resorted to, such as trunnion-sights, or a white line painted on the mortar-bed parallel to the axis of the bore when level; but the first plan is preferable.
The guns 'teams of oxen and horses were being led back into the shelter of the oaks while squads of gunners hoisted the hugely heavy cannon barrels out of their rear travelling trunnion holes and moved them into the forward fighting holes where other men used hammers to fasten the capsquares over the newly placed trunnions.
The United States siege carriage of the 1860's had no extra trunnion holes, but a "traveling bed" was provided where the gun was cradled in position 2 or 3 feet back of its firing position.
Some late eighteenth century field and siege carriages had a second pair of trunnion holes a couple of feet back from the regular holes, and the cannon was shifted to the rear holes where the weight was better distributed for traveling.
The trunnion sight, a graduated sight attached to the trunnion, could be used when the muzzle had to be elevated so high that it blocked the gunner's view of the target.
Use of tangent and trunnion sights brought gunnery further into the realm of mathematical science; the telescopic sight came about the middle of the nineteenth century; gunners were developing into technicians whose job was merely to load the piece and set the instruments as instructed by officers in fire control posts some distance away from the gun.
Basic proportions for the carriage were obtained by measuring (1) the distance from trunnion to base ring of the gun, (2) the diameter of the base ring, and (3) the diameter of the second reinforce ring.
The lengths of the trunnions are measured with the foot-rule, and the diameters of the rimbases by that of the exterior rim of the trunnion-gauge.
The remaining parts of the brackets are the trunnion-holes _b_, steps _c_, quarter-rounds