The Works Of Messrs. Schneider And Co.

244 MESSRS. SCHNEIDER AND CO.’S WORKS. munication is re-established by hånd, through a vent made in the thickness of the valve-chest, when it runs out again by gravity. The whole of the system comprising the gun, the mounting and its frame, is fitted to a bolster, which rests on the platform, with the interposition of a series of coned rollers. The bolster supports the tube for the passage of ammunition, as well as the movable shell of the turret. A circular casing of armour fitted to the deck, and a space which surrounds the central tube, complété the protective part of the installation. Elevation is given by a crank which gears the pinion that works a toothed sector fitted to the left cheek of the carriage. The mechanism is completed by a set of holding-back toothed wheels, worked by the crank, and which set in motion the small pinion of the elevating mechanism. Lateral training is obtained eitlier by hånd or by power, by means of a pinion which engages in the circular rack fixed on the upper deck. This pinion is set in motion either by a set of gearing worked by a pinion keyed on a horizontal shaft which goes through the cheeks of the mounting and carries the working cranks, or by a steam motor which actuates an endless screw with an hélicoïdal wheel, carrying a regulating device of the type provided for the elevating mechanism. The hoist is made with three compartments ; it is guided by rollers which travel inside the central tube, and there are two chains mounted on drums, that are turned by hånd or power. In the former case, tlie drums are operated by means of cranks, plate chains, and gearing ; when a motor is used, the transmission consista of an endless screw with hélicoïdal wheel and gearing keyed on the endless screw- shaft, that work the toothed wheel of the drum. When the top staging is reached, the half-cartridges are removed by hånd, the projectile being raised to the height of the breech by a winch fixed to the roof of the inner shell of the turret. Closed Turret for 270-Millimetre (10.630-In.) Gun. — Turrets of this type (see Fig. 802, on page 243), have been built for varions armoured gunboats. They consist of the mounting with its slide, the turret, the training mechanism, and the ammunition hoist. In order to obtain the necessary elevation, the gun is mounted on a carriage which trav els 011 a slide, turning' around horizontal trunnions in brackets carried by the movable platform. The carriage is provided with buffers, and is guided in its slides by lateral damps ; the gun is held in the carriage by grooves and pins. The slide con- sists of beams stayed together, and between them are placed the two recoil cylinders. An Intermediate stay, which rests on the piston-rod of the training press, carries the mechanism that régulâtes the recoil as well as the running out and in of the gun. The hydraulic brake consista of two lateral cylinders bolted to the slide, the piston-rods of which have a constant diameter on their whole length and extend on both sides of the piston. There is in connection with these cylinders an intermediate distribution ehest, fitted with a loaded valve, and to which are brought the conduits that are connected with the pipes extending to the front and rear of the recoil cylinders. A regulating rod complétés the system, which works as follovvs : When the gun is fired, it draws back with it the carriage and piston-rods, which are fixed to its rear cross- beam, the liquid flowing to the front end of the cylinder after lifting the valve of the distribution ehest. The rapidity in flow of the liquid is governed by the regulating rod, which is controlled by a suitable sliding link placed under the carriage ; this maintains a practically uniform pressure in the recoil cylinders during the whole period of recoil. When the recoil ceases, the valve falls on its seat and Interrupts all communication between the front and the rear of the cylinders, the gun reniaining run in. To run it out ready for firing, the water under pressure is directed to the rear of the pistons, the front part of the cylinders being exhausted. The carriage and slide rest on the movable platform of the turret, in the centre of which is the opening of the tube for the passage of ammunition. The platform is provided with the drum round which the chains pass that operate the lateral training. To the platform is also attached the armour-plating of the turret, with its roofing, and an armoured hood for protecting the gunner. The central tube is surrounded by a casing that rests on the deck and supports the fixed protective armour. Between the platform and the supporting framework is placed the series of truncated conical rollers, on which the turret revolves under the action of the turning drum and chain. The hydraulic cylinder for elevating the gun is double- acting. The piston-rod extends on both sides, and is made with spherical joints. The breech end of the gun is raised or lowered, according to whether the lower part of the cylinder is in communication with the inlet or outlet of water under pressure. A bolt, worked by a lever is provided, with the object of fixing the gun in its loading position. For lateral training, two sets of hydraulic gear are arrangée! horizontally on the lower part of the system. The working chains rise first vertically, pass round trans- mission pulleys, and then round the drum fixed underneath the platform, and referred to above ; they then return to the hydraulic cylinders. The motion is obtained by placing one or other of these cylinders in communication with the accumulator. The valve distribution ehest is within easy reach of the gunner. A set of fixed and loose toothed wheels produces more or less rotation one way or the other, or an instantaneous stoppage of the system. A special brake holds the turret fast at the position chosen for firing. Ammunition is raised from the magazines to the breech by means of an hydraulic hoist, provided with three stagings that can hold a projectile and two half- cartridges. The ammunition tray, mounted on a roller truck, rests on a plate which is raised by means of a telescopic apparatus ; it is guided by two shoes, which move in the slides carried by the tube. On reaching the upper end of the travel, the rollers of the truck