Carriage trucks (wheels), unless they were made of cast iron, had iron thimbles or bushings driven into the hole of the hub, and to save the wood of the axletree, the spindle on which the wheel revolved was partly protected by metal. The British put copper on the bottom of the spindle; Spanish and French designers put copper on the top, then set iron "axletree bars" into the bottom. These bars strengthened the axletree and resisted wear at the spindle.
A 24-pounder fore truck was 18 inches in diameter. Rear trucks were 16 inches. The difference in size compensated for the slope in the gun platform or deck—a slope which helped to check recoil. Aboard ship, where recoil space was limited, the "kick" of the gun was checked by a heavy rope called a breeching, shackled to the side of the vessel (see fig. [11]). Ship carriages of the two-or four-wheel type (fig. [31]), were used through the War between the States, and there was no great change until the advent of automatic recoil mechanisms made a stationary mount possible.
Figure 31—U. S. NAVAL TRUCK CARRIAGE (1866).
With garrison carriages, however, changes came much earlier. In 1743, Fort William on the Georgia coast had a pair of 18-pounders mounted upon "curious moving Platforms" which were probably similar to the traversing platforms standardized by Gribeauval in the latter part of the century. United States forts of the early 1800's used casemate and barbette carriages (fig. [10]) of the Gribeauval type, and the traversing platforms of these mounts made training (aiming the gun right or left) comparatively easy.
Training the old truck carriage had been heavy work for the handspikemen, who also helped to elevate or depress the gun. Maximum elevation or depression was about 15° each way—about the same as naval guns used during the Civil War. If one quoin was not enough to secure proper depression, a block or a second quoin was placed below the first. But before the gunner depressed a smoothbore below zero elevation, he had to put either a wad or a grommet over the ball to keep it from rolling out.
Ship and garrison cannon were not moved around on their carriages. If the gun had to be taken any distance, it was dismounted and chained under a sling wagon or on a "block carriage," the big wheels of which easily rolled over difficult terrain. It was not hard to dismount a gun: the keys locking the cap squares were removed, and then the gin was rigged and the gun hoisted clear of the carriage.
A typical garrison or ship cannon could fire any kind of projectile, but solid shot, hot shot, bombs, grape, and canister were in widest use. These guns were flat trajectory weapons, with a point-blank range of about 300 yards. They were effective—that is, fairly accurate—up to about half a mile, although the maximum range of guns like the Columbiad of the nineteenth century, when elevation was not restricted by gun port confines, approached the 4-mile range claimed by the Spanish for the sixteenth century culverin. The following ranges of United States ordnance in the 1800's are not far different from comparable guns of earlier date.
Ranges of United States smoothbore garrison guns of 1861