Four-inch Fifty Caliber Rapid-Fire Gun on Pedestal Mount
Extraction of cartridge case by opening of breech mechanism. Weight of gun, 6,170 pounds. Length of gun, 205 inches (51.2 calibers). Weight of projectile, 33 pounds. Travel of projectile in bore, 165.6 inches (41.4 calibers). Weight of charge, 15 pounds of smokeless powder. Muzzle velocity, 2,900-foot seconds. Muzzle energy, 1,928-foot tons. Weight of mount with shield, 9,470 pounds. Thickness of shield, 2 inches of nickel steel. Gun equipped with telescopic and night sights and with electric and percussion pull-off firing gear.
Courtesy of the Bethlehem Steel Co.
Military cannon are divided into three classes, based upon the length of caliber, and technically known as guns, mortars and howitzers. In guns the length is relatively great, in mortars relatively small, compared to their calibers. Howitzers form a class between guns and mortars in length. The field guns of the American army are the 3.6-inch breech-loading mortars, and the 3.6-inch heavy and 3.2-inch light guns. The siege guns in the service are the 5-inch siege guns, the 7-inch howitzer, and the 7-inch mortar. The coast defense artillery consists of the 8-, 10-, 12- and 16-inch guns and the 12-inch mortars. In the recent European war very heavy cannon were used for field service, pieces of the size usually placed in forts being drawn to the field by powerful tractors, set on concrete platforms and used in attacks on fortified cities. It was through the use of such ordnance that the German army so easily reduced the strongly fortified Belgian cities.
Fluid Compression Plant
While still in a molten condition in the mold, the steel used in manufacturing guns and shafting is subjected to hydraulic pressure until the ingot has cooled, thus insuring the solidity of the metal. The upper head of the compressor weighs 125 tons, and the lower one, including the cylinder through which the hydraulic pressure is applied, 135 tons.
Courtesy of the Bethlehem Steel Co.