Page:EB1911 - Volume 20.djvu/254

Rh but they have existed for a specific purpose, and ordnance originally designed for quite other functions has, from the exigencies of war, been occasionally utilized in the field, as was the case in South Africa and Manchuria, but the heavy field battery as we know it to-day is a new military product. Its rôle is an extensive one, as it embraces many of the functions of ordinary field guns as well as some of those usually attributed to fight siege pieces. In the heavy field armaments of the Powers as they stand at the present time will be found guns, howitzers and mortars, and projectiles that vary from 50 ℔ to more than five times that weight, and no boundary line can be assigned which will separate these field equipments from those of the light units of a siege train It will be convenient to consider in turn the three natures of ordnance (guns, howitzers and mortars) employed and to quote some typical instances of each kind.

''The United States 60 pr. Gun''.—This gun and its equipment are of modern type (1904) Its general appearance is shown in figs. 69 and 70, Plate V. The calibre is 4·7″; the charge 5·94 ℔ of smokeless powder and the muzzle velocity developed is 1700 f.s. Fixed ammunition is employed, and with an elevation of 15° the range is 7600 yds. The weight of the equipment limbered up is given as 71 cwt.: it is known as a siege gun.

In its general aspect the carriage resembles a field carriage, but of stronger type, with a special arrangement of cradle. In fig. 71 two sections are given; the cradle, it will be seen, consists of three cylinders (seen in section in the upper figure) which are bound together by broad steel bands; the two outer cylinders carry rails r upon which the gun slides in recoil. The centre cylinder contains the hydraulic gear for checking recoil, the two outer contain the running-up springs s. These springs are arranged in three concentric columns, the front end of each outer column being connected to the rear end of the next inner column by a steel tube, flanged outwardly at the front end and inwardly at the rear end. A rod carrying a head which acts on the inner coil only passes through the centre of the cylinder and is fixed to a yoke that is connected with a lug at the breech of the gun. The flanged tubes thus convey the pressure from the innermost coil to the next outer coil and finally to the outermost coil, so that in each cylinder the springs work in tandem and have a long stroke with short assembled length. It is thus seen the recoil takes place partially on the carriage and only a portion of the energy remains to tend to cause movement in the mounting.

The cradle is supported by trunnions in the casting y, which is itself seated in the casting p, which forms a bearing for it. This bearing is mounted between the front ends of the trail brackets, its rear end embracing the hollow axle x. Attached to the lower surface of y is the traversing bracket b, which extends to the rear under the axle and forms a support for the traversing shaft t and for the elevating mechanism.

For travelling (Plate V., fig. 69) the gun is withdrawn to the rear and the breech is attached to a holding-down arrangement about the middle of the trail. A spade is hinged at the point of the trail.

''The British 60 pr. Gun''.—This is known as a heavy battery gun; its calibre is 5″, its length 32 calibres, its weight 39 cwt.; its charge is 9 ℔ of cordite, its muzzle velocity 2080 f.s. and its effective shrapnel range 10,000 yds. The weight behind the team is 106 cwts., 3 qrs.

The German 10 cm. Gun is called a heavy battery gun; its calibre is 4″, its effective shrapnel range is 5750 yds., but common shell can be used up to 11,000 yds. The organization is a six-gun battery, but a platform has always to be used.

A howitzer is a comparatively light piece that fires a comparatively heavy shell with a comparatively low muzzle velocity, and changes in range are effected sometimes by alteration of charge as well as of elevation. On the continent of Europe howitzers are more popular than guns for heavy field batteries and light siege units.

The French 15 cm. (Rimailho) Howitzer.—This piece is at the present time very popular in France, where, in 1907, some 120 batteries of the field army were said to be armed with it. It came into being from the conversion of an old pattern siege howitzer and its adaptation to a new form of carriage, according to the plans of Commandant Rimailho. The gun (canon de 155 R) is a short piece, made of steel, with a calibre of 6·1″; the shell weighs about 94 tb and has an effective range of 7000 yds. The breech opens automatically after each round and a rapidity of fire of from 4 to 5 rounds a minute is claimed. The howitzer is supported on two trunnions near its rear end so that the weight pivots about a point near the breech, with the result that the latter remains nearly 5 ft. above the ground level at all angles of elevation; space is thus left for recoil, which is checked by a buffer, the construction of which is a secret; running-out springs are provided to return the gun to the firing position. The piece recoils in a cradle to which is attached the elevation scale, but the elevating gear is independent of the carriage proper; the line of sight is also independent. The howitzer has a special transporting carriage, but it can be placed on its firing carriage, it is said, in two minutes. The weight behind the teams is in each case about 47 cwt. On a war footing three ammunition wagons per howitzer would be provided.

The German 75 cm. Howitzer.—The Germans also possess a 15 cm. howitzer of modern type; its rate of fire is 2 to 3 rounds a minute; its shell is 87 ℔ in weight and the weight behind the team is about 53 cwt.

The British 6″ B.L. Howitzer.—This piece is made of steel, it weighs 30 cwt., its shell weighs 122 ℔ and has an effective range of 7000 yds. The weight behind the team is 85 cwt.

Fig. 72 shows the howitzer and cradle A mounted on the travelling carriage, from which it can be fired up to an angle of 35°: in fig. 73 the wheels have been removed, the trail B has been lowered on to the pivot plate C and secured to a pivot plug screwed into the plate: to the trail is fitted the top carriage D, and when the howitzer and cradle are thus mounted 70° elevation can be given. EB1911 - Ordnance Fig 72.png . 72.—Diagram, of British 6-in. B.L. Howitzer.

The howitzer recoils through the cradle, in which are two hydraulic buffers side by side, fig. 74, whose piston rods E are attached to the howitzer so that the recoil of the latter draws the pistons J to the rear. Consider now, in fig. 74, the right buffer only; forged in one piece with the piston and piston rod is a tail rod F of larger diameter than the piston rod, and in the front of the cylinder is an annular bronze casting G, called a floating piston, which bears against the rear of the springs. On discharge, the howitzer slides along the cradle to the rear, the piston rod E is drawn out of the cylinder and the tail rod F is drawn in, and from its larger diameter causes a pressure of oil against the floating piston G, which slides forward and compresses the springs which are prevented moving by the rods H. The action is the same in each buffer. After recoil the springs expand and return the howitzer into the firing position.