The Works Of Messrs. Schneider And Co.

THREE-MOTION BREECH-MECHANISM FOR QUICK-FIRING GUN. 195 completely closed. To prevent all backward movement of the breech-block, the hand-lever is provided with a cam, which on closing the breecb, fits in a mortice. As tlie vent remains masked until the breech is completely closed, there is no risk whatever of prématuré fire. Type 2 (Figs. 626 to 629, Plate CXII.).—In this type, firing is effected by a slide-bolt, which acts by percussion, by means of a line. No springs are used, and the striker is j free only when the breech is completely closed. The percussion fuse is on the Schneider-Canet system, and is [ ejected automatically from the block in starting the opening motion of the breech. To prevent accidentai opening of the breech-block, the lever is made with a cam, which fits in a mortice when the breech is completely placed in the vent. The striker is set by hånd, and acts by means of a firing line. The lever is provided with a cam that fits in a mortice when the breech is completely closed, thus preventing the throwing back of the breech- block. The vent being closed as soon as the operation of opening is commenced, and the striker being opposite the fuze only when the breech is closed, there is no risk of prématuré fire. The gun can be fired both by percussion and with friction fuze. In this type only a few slight alterations would be required to use metallic cartridge- cases instead of the plastic obturator. The above brief descriptions explain the chief charac- teristics of the earlier types of this system of breech mechanism ; and it will be seen that these characteristics Figs. 638 to 640. Sections of Breech Mechanism, Type 4. closed. The gun is secure against prématuré firing, as the striker can only act also when the breech is completely closed. Type 3 (Figs. 622 to 625, Plate CXL).—This arrange- ment is practically similiar to the preceding one, but is used for larger calibre guns. The varions parts of the mechanism have been simplifiée! and bidden as mueh as possible in the breech itself. Type 4 (Figs. 634 to 637, Plate CXIIL, and Figs. G38 to 640).—In this type the gun is fired by means of a bolt that slides in the breech-piece and acts by percussion. On starting the opening of the breech, the bolt, being no longer opposite a rectangular space cut in a circular groove on the rear end of the gun, the vent cannot be freed ; moreover, as the striker is maintained slightly lifted, it would not be opposite to the fuse had this already been J are still more defined in the patterns that have been j manufacturée! subsequently. Special Type.—We now pass to a further development, j illustrated by Figs. 630 to 633, Plate CXII. In this, the three movements are still effected successively, but they are continuons, so that practically they are reduced to one operation. The breech-piece consists of a cylindrical screw, but the threads are set out as on a hélicoïdal sur- face ; there are two threaded parts and two interruptions. The block is carried by a bracket which pivots round a vertical liinge-bolt. The obturator consists of a plastic elastic disc of special shape, pJaced between the movable head and the front end of the breech-piece ; or metallic Cartridges may be used. Firing is effected by a sliding bolt iitted with a striker, that acts by percussion through a spring pressing against a tappet on the rear end