Near the rear end of each cheek, and outside, a heavy trail-handle of iron is placed, and used in manœuvring the piece. On the ends of the axle truck wheels are placed, with mortises sloping outwards in the direction of the radii, for the insertion of the handspikes in running from battery.
The elevating apparatus consists of a cast-iron bed-plate, secured to the rear transom; an elevating screw and brass nut; the nut being acted on by an oblique-toothed wheel, turned by a handle placed outside the right cheek.
62. Describe the chassis.
It consists of two rails and a tongue, joined by two transoms, and supported on traverse-wheels in front and rear. The track on each rail is curved up at each end, and provided with hurters to prevent the carriage from running off the chassis. A prop fastened under the rear end of the tongue prevents the chassis from upsetting backwards in firing heavy charges, and may be used as a point of support in raising the chassis. An iron fork is bolted to the under side of the front end of the tongue, to which is bolted an iron tongue. An opening in the masonry below the embrasure, is left for this tongue, and it is secured in its place by dropping the pintle from the embrasure down through the eye of the tongue.
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63. Where is the flank-casemate carriage employed?
It is especially adapted to the mounting of the 24-pdr. iron howitzer in the flanks of casemate batteries, for defending the ditch; and both the gun-carriage and chassis are narrower and lighter than the other casemate carriages.
64. Describe the gun-carriage.
The cheeks are made of white oak, and connected by two iron transoms, the front one projecting below the cheeks, and resting on the chassis with a projection on the bottom of it, fitting in between the rails. The bottom of the trail has the same slope as the upper surface of the chassis on which it rests; so that when its eccentric-roller is out of gear, the rear parts of the cheeks fit the rails. The remaining portion of the bottom of the cheek makes an angle with the rail, and has in front a fork, and a roller which runs on the rail of the chassis when the eccentric is in gear. Each cheek has on the side a trail-handle and a manœuvring-ring. In rear of the rear transom is placed an eccentric-roller, having a projection in the middle of it, just large enough to fit in between the rails of the chassis, and guide the trail of the carriage. When this roller is in gear, the weight of the trail rests upon it, while that of the front part of the carriage is thrown upon the front rollers, and the piece is then easily run in and out of battery; but the roller being out of gear, as when the piece is about to be fired, the weight rests upon the rear part of the cheeks and the front transom, and friction is brought into play to diminish the recoil. Cap-squares are used with this carriage.
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