The wheels and wheel fastenings are interchangeable with those of the gun carriage and the limber. The caisson road brake is modeled after that of the gun carriage, all parts as far as possible being interchangeable. The frame upon which the ammunition chest rests, is diamond shaped, and consists principally of two steel side rails riveted to lugs on the axle, meeting in front to form the lunette for attachment to the limber, and in rear to form a pintle for attachment of another caisson in case it is desired to tow several caissons by one team and limber, as for instance in the ammunition train. In other respects the construction is similar to that of the limber excepting that the ammunition chest is much larger and has a capacity of 70 rounds. The front of the chest and the chest door are made of armor plate. A bracket for the fuse setter is also provided. An apron shield, similar to the one on the gun carriage is hinged under the axle, giving the cannoneers at the caisson full protection. A spare-pole body can be carried under the caisson frame, large end of pole to the front. On the sides and front of, and under the ammunition chest, suitable straps, brackets and connections are provided for securing all tools and accessories. To lock the caissons and limbers, a padlock is provided. These locks are interchangeable and can be unlocked by the same key. This key is marked “Ammunition.” Weights and Dimensions. Weight of caisson only, completely equipped and loaded 2820 lbs. Weight of caisson and limber, both completely equipped and loaded with 106 rounds 4560 lbs. Number of rounds of ammunition carried in caisson only 70 Nomenclature of important parts of Caisson:— Wheels Wheel fastenings, complete Axle Middle-rails Side rails Pintle with bearing, consisting of— Pintle Pintle latch Pintle-latch spring Name plate Channel supports Frame handles Lunette, with nut Caisson prop, with chains Road brake, consisting of— Brake-beams Brake shoes Brake rods Brake-rod springs and covers Brake shaft, with two keys Brake segment Segment rack Brake lever Spare-pole fastening Ammunition chest, consisting of— Diaphragms Grip-straps Paulin-straps Chest rails Foot rest Handrails Door props Door handles Hand rails Supports and Brackets for attaching various tools and accessories Apron Apron latches Fuze-setter bracket Fuze-setter latch Fuze setter Paulin Picket ropes Various tools and accessories Spare pole To Dismount and to Assemble Parts of the Gun and Carriage.