DESCRIPTION.
| Light. | Heavy. | ||
| Calibre | inches | 1.45 | 1.45 |
| Length of gun | " | 46.4 | 70.4 |
| Height of trunnions above tread | " | 35 | 42.4 |
| Length of gun-barrel | " | 29.1 | 50.1 |
| Number of barrels | 5 | 5 | |
| Weight of each barrel | pounds | 30.8 | 79 |
| Length of rifled bore | inches | 24.7 | 43.4 |
| Number of lands | 12 | 12 | |
| Pitch of rifling | degrees | 6 | 6 |
| Weight of gun complete | pounds | 495 | 1045 |
The gun consists of five main parts: the group of barrels, the breech-piece, the mechanism, the frame, and the attachments.
THE GROUP OF BARRELS.
The five barrels are assembled around a main shaft by being secured in two bronze assembling-disks. Both disks are bolted to the main shaft, so that barrels, disks, and shaft revolve together. The main shaft goes into the breech-piece, and has screwed and bolted to its end a heavy steel pin-wheel, which connects the barrel-system with the mechanism.
Fig. 83.
THE BREECH-PIECE.
This is a cast-iron block, the front half solid and pierced with the channels necessary for feeding, loading, firing, and extracting ammunition, and the rear half hollow to form a chamber for the mechanism, with guideways and journals for its movement and support. In the upper front face a channelway is cut from the loading-hole around almost to the firing-point, the bottom being inclined so that as the cartridge moves along it during the revolution of the barrels it is pushed forward and close home.
The forward face is reinforced at the firing-point by a steel face-plate countersunk in it, through which the firing-pin hole is pierced. The seat for the pin-wheel is in the rear face of the solid part. This pin-wheel can only be mounted on the main shaft after the end of the latter has been inserted in its journal; and in order to put the locking-pin of the pin-wheel in place it is necessary to have a hole pierced radially from the outside of the breech-piece. This hole is kept constantly closed by a tap-screw. The rear end of the breech-piece is closed by a bronze door, hinged at the bottom, and secured by a screw-bolt at the top. On the outer sides of the breech-piece shoulders are cast to form seats for the shafts of the frame.
As the worm-shaft does not extend completely across the chamber of the breech-piece, a small journal-seat is cast just to the left of the centre of the chamber. In the right lower corner of the chamber is a guideway for the firing-bolt; on the left side is a slotway for the extractor; a small journal is pierced through the side for a cog-wheel, which is held in place by a keep-pin. In the left upper corner is a guideway for the loading-piston.
THE MECHANISM.
The work of the mechanism consists in revolving the barrels, loading, firing, and extracting.
The revolution of the barrels is a simple gear movement. The loading and extracting are reciprocal movements; that is, while a cartridge is being pushed into one barrel an empty cartridge-case is being drawn from another. The firing is accomplished by the firing-bolt, which is drawn backward by its cocking-arm pressing on the cam of the worm-wheel, and then thrown violently forward by the mainspring, when the arm drops from the end of the cam. The piece has the ordinary trigger arrangement.
In order to keep the cartridges from crowding down upon the loading-piston a small feed-gate is hung loosely in the feeding-hole. In the forward movement of the piston a small nib at its forward end catches behind the gate and lifts it up, thus cutting off the feed.
THE FRAME AND ATTACHMENTS.
The group of barrels and the breech-piece are bound together by the frame, and the whole system is supported by the trunnions in a forked pivot. The frame is a light bronze casting, consisting of two hollow side-bars connected by two hollow cross-bars. The forward one is journalled for the forward end of the main shaft, and the rear one is in line with the trunnions. A half-ring spans the shaft over the forward assembling-disk to form a seat for the front sight. The rear ends of the shafts are bolted in seats in the side of the breech-piece. The trunnions form part of the casting of the frame. The right forward cap-square bolt has a lever for clamping the piece at any desired elevation.
The pivot rests in a socket, in the side of which is a clamp for fixing the gun in any desired direction.
The feed-trough holds about eight cartridges.
The Rear Sight consists of a bar having its right edge arranged with alternate notches and points for each 100 yards or other unit. These notches and points are so arranged as to allow for the natural drift of the projectile. The bar is hinged at the bottom to lie flat on the breech-piece when not in use.
The Front Sight is of the ordinary steel-point pattern.
THE ACTION OF THE MECHANISM.
Suppose the crank to be in continual motion.
A cartridge is placed in the introduction-trough, the piston pushes it into the barrel, the barrels begin to revolve, and the cartridge is carried on until it arrives before the firing-pin, held in the solid part of the breech, and which has, in the meantime, been retracted by the action of the cam. As soon as the cartridge has arrived in position the barrels cease to revolve and the primer of the cartridge is struck by the firing-pin and discharged; the revolution of the barrels begins again, and the fired cartridge-shell is carried on until it comes to the extractor, which in the meantime has arrived up to the barrels, and the cartridge-head rolls into it. As soon as the head is laid hold of by the extractor the barrels again cease to revolve, and during this period the cartridge-shell is withdrawn and dropped to the ground. During every stoppage of the barrels the gun is supplied with a new cartridge, the firing and extraction are also performed, and a continuous but slow fire is kept up. Supplying the gun in this manner with single cartridges, about thirty rounds per minute may be fired.
DISMOUNTING AND MOUNTING THE MECHANISM.
To Dismount.—1. Open the breech-door by unscrewing the door-bolt. As the mainspring presses against the door, one hand should be pressed against the door to keep it from flying open.
2. Withdraw the firing-bolt by pulling straight out.
3. Detach the mainspring by first turning it completely over and then withdrawing its keep-pin.
4. Take out the thumb-screw which secures the extractor-crank to the worm-axle.
5. Withdraw the worm-axle by pulling straight out on the crank; and as the extractor-crank and worm-wheel slip off, remove them.
6. Pull out the extractor.
7. Pull out the loading-piston.
8. Unscrew the keep-pin of the cog-wheel and take the latter out.
This completes the dismounting of the mechanism.
To Mount.—Proceed in the inverse order, bearing in mind that in inserting the loading-piston it must be pushed in to its extreme forward limit, as marked by arrows on its forward end and on the rim of the feeding-hole, before the extractor is inserted. Also, in inserting the worm-axle the most convenient position is with the feather up, so that the extractor-crank will mount when it is turned arm down and to the rear. This is not necessary, but is convenient in assembling.
To Dismount Completely.—1. Turn the barrels until the arrow on the rear assembling-disk marked "Dismount" is opposite the arrow on the right upper quarter of breech-piece.
2. Enter a punch in the hole in the breech-piece and back out the keep-bolt of the pin-wheel.
3. Unscrew and take out the pin-wheel.
4. Unscrew the four bolts which secure the frame to the breech-piece.
5. Slip the breech-piece off to the rear.
6. Remove the group of barrels from the frame.
Mounting is done in the inverse order. Start the pin-wheel on before pushing the breech-piece entirely into place. In driving in the keep-pin of the pin-wheel be careful that it is close home so as not to grind in the journal. Also, before dropping the keep-pin in turn the barrels until the arrow marked "Mount" is opposite the one on the breech-piece.
CARE AND CLEANING REQUIRED.
Apply the rules given for mountain-artillery, page 4.
In scrubbing out the barrels it is always best to turn the one to be scrubbed to the extractor-hole, as this position gives the most room for thorough work and the water does not slop into the breech-piece. Elevate the gun slightly and put the water-bucket under the extractor-hole.
When cleaned and mounted, pour a little oil in the oil-holes and revolve the mechanism a few times to spread it on the bearings.
AMMUNITION.
The ammunition is similar to that used in breech-loading small arms, and consists of the projectile, to the base of which is crimped a metallic cartridge-case containing the powder-charge, and being provided with a percussion-cap for centre-fire. The charge of powder is loaded into the brass case and shaken down, and on the top of it is placed a felt lubricating-wad, which leaves sufficient end to the case to allow it to be crimped to the base of the projectile. The projectiles consist of cast-iron shell, steel shell, and canister. The nose of the first is truncated to give a seat for the nose fuze; that of the second comes to a sharp point, and its fuze is in the base. The canister consists of a thin drawn brass case, almost hemispherical at the head, filled with hardened lead balls packed in sawdust.
| Light. | Heavy. | ||
| Weight of shell, empty | Oz. | 14.4 | 16 |
| Weight of shell, loaded | " | 16 | 19 |
| Bursting-charge | " | 0.7 | 0.8 |
| Number of fragments | 15 | 15 | |
| Weight of canister | Lbs. | 1.25 | 1.25 |
| Number of bullets | 28 | 28 | |
| Weight of cartridge-case, empty | Oz. | 3 | 3.4 |
| Weight of powder-charge | " | 2.8 | 3.8 |
| Total weight of cartridge complete, shell | Lbs. | 1.4 | 1.7 |
| Total weight of cartridge complete, case | " | 1.6 | 1.75 |
THE CARRIAGE.
Fig. 84.
| Light. | Heavy. | ||
| Diameter of wheel | Inches. | 45.2 | 55.1 |
| Weight of wheel | Lbs. | 99 | 187 |
| Width of tread | Inches. | 47.2 | 60.2 |
| Weight of carriage without shield | Lbs. | 550 | 990 |
| Weight of shield | " | 220 | 282 |
| Weight of gun, carriage and limber fully equipped | " | 2112 | 3487 |
The trail is formed of two brackets connected by bolts and two transoms, and having a gun-metal rest for carrying the trunnion-saddle, the rear ends being connected by the trail eye-piece, made of cast steel. The brackets diverge at the trunnions, the axle is of steel, and the wheels have metallic naves and tires.
The gun-traversing arrangement, giving 4° deflection to the right or left, consists of a cast-steel saddle with trunnion-bearings, and works in the gun-metal rest riveted to the brackets.
The elevating and traversing arrangement consists of a steel ball-and-socket elevating-screw working in an oscillating bearing; this bearing, and with it the elevating-screw, can be traversed right and left by means of a small hand-wheel on the left side of the trail, and this causes the trunnion-saddle with the gun to pivot around the centre of the saddle.
On the right side of the trail there is a compressing-handle to lock the elevating-screw, so as to make it immovable during firing and whilst travelling. The handspike, of iron tubing, is hinged to the trail.
The brake is of the following description: Each axle-arm has a screw cut on its extremity; this carries a nut forming a conical cap, partly enveloping the inner side of the wheel-nave, which is also conical, to fit the inside of the cap; and has a crank-arm by which it can be revolved on the axle. When screwed up, this cap grips the cone of the nave of the wheel until the latter is immovably locked by the friction of the cones.
A shield, of three parts, made to fold together, thus forming seats for two men, is sometimes provided. It is of steel plate three sixteenths of an inch thick.
The carriage carries the following implements: A sponge on the right bracket, and two handspikes beneath the trail; in the tool-box (which is between the brackets) are carried the feed-trough, hand-crank, rear sight, screw-driver, oil-can, reserve mainspring, reserve firing-pin, hammer, punch, and a universal wrench.
THE LIMBER.
| Light. | Heavy. | ||
| Weight of limber empty | Lbs. | 605 | 913 |
| Weight of limber loaded | " | 1067 | 1452 |
| Number of rounds in limber | 300 | 300 |
The limber is formed of four futchells,—the outside ones of flat steel, the inside ones and the splinter-bar being of angle-iron,—a platform-board, and a foot-board of oak. The axle is of hollow wrought iron; wheels same as for carriage. The futchells and splinter-bar are all riveted together, and the cast-steel limber-hook is riveted in between the inside futchells: the axle is secured to the bed by three bearings.
The pole lets into an iron frame and is held by two bolts with threads and nuts. The single-trees, of metal, are hung to eye-plates under the ends of the brackets.
The ammunition-chest is made of steel plate and carries 300 rounds in two compartments, one of which holds 100 rounds packed in ten steel feed-cases ready for rapid firing.
The limber carries the following implements: A set of intrenching-tools, axe, water-bucket, traction-rope, cushions for seats, etc.