The Works Of Messrs. Schneider And Co.

182 MESSRS. SCHNEIDER AND CO.’S WORKS. worked by a hélicoïdal screw from an hand-wheel. The gun is trained by means of a pinion and toothed l’ing attached to the bolster, the pinion being actuated by a hand-wheel, a system of gearing, and a chain and hélicoïdal screw. The hydraulic recoil cylinders, which form part of the gun-carriage, are provided with rods fixed to the front of the slide. They are in communication with each other by means of two pipes. I2-Centimetre (4.724-In.) Gun. Type 1890 (Figs. 598 and 599).—Guns of this type have been delivered to the Mexican Government for the armament of the training- ship Zaragoza; they have included two series, of different lengths, as shown below : vided with a cam that enters a mortice only wlien the breech is completely closed, thus acting as a safety block. This cam serves also, in case of need. to disengage the obturator from the walls of the gun chamber, when the lever is brought clown after having disengaged the threads of the breech-screw. The obturator consists of special-shaped plastic dise placed between the movable ring and the front end of the breech-screw. A boit contains the firing device, which works by percussion. The vent remains closed as long as the breech is not locked, thus preventing prématuré firing as the percussion tube cannot be placed in the vent until the closing of the breech is complété. The striker is worked by a trigger and a line. Fig. 598. 12-Centimetre Gun and Mounting (26 Calibre) ; Model, 1890. — 26 Calibres Long. 43 Calibres Long. Weight of gun... 2888 kilogs (63531b.) 3428 kilogs. (7541 1b.) ,, mounting ... 2290 kilogs (5038 1b.) 2290 kilogs. (5038 1b.) ,, shield ,, projectile (armour-pierc- ing shell) Weight of charge (prismatic black 625 kilogs (1375 1b.) 625 kilogs. (1375 1b.) 21 kilogs. (46.2 1b.) 21 kilogs. (46.2 1b.) powder) 12 kilogs. (26.4 1b.) 12 kilogs. (26.4 1b.) Pressure 2400 kilogs. (15.24 tons per square inch) 2400 kilogs. (15.24 tons per square inch Muzzle velocity ... ... 660 m. (2165 ft.) 710 m. (2329 ft.) Angles of elevation ... + 25 deg. -8 deg. + 22 deg. — 8 deg. The breech mechanism is the same for both guns ; it consists of the breech-block with interrupted screw, carried by a slide bracket which pivots on a vertical hinge at the back of the gun. The block is operated by a lever pro- Tlie central pivot mounting consists of a circular bolster fixed to the deck and roller path ; a slide formed of two brackets connectée! by cross-stays constitutes a platform that surrounds the pivot and bolster ; the gun-carriage proper consists of the usual slides and two recoil cylinders that communicate with each other through a pipe and slide 011 the brackets. To elevate the gun, a differential device, worked by a handwheel, is provided ; it acts through a friction cône on a pinion that gears in a toothed sector fitted to tlie left of the gun. The gun is trained by anotlier handwheel and a pinion which gears in a circular rack fitted to the bolster. The recoil cylinders are of the Schneider-Canet type, with central counter-rods. Both the pistons and rods remain fixed during recoil. Each piston is provided with valves that rernain open only under the action of the recoil on the liquid contained in the cylinders. Automatic return of the gun takes place with reduced speed in order to reduce shocks.