The Works Of Messrs. Schneider And Co.

SINGLE-MOTION BREECH-MECHANISM. 201 block itself and in the direction of its main centre line. The breech support carries the whole of the mechanism in the varions positions it takes, and pivots round a vertical bolt held in a lug fitted at the side of the gun ; it is provided with the double-acting Schneider- Canet lateh, already described in a preceding chapter, and which serves to connect, at the proper moment, the varions elements. The hand-lever operates a compound pinion mounted on the pivot of the breech. support, and which consists of an entliess screw that engages the toothed wheel of the breech-screw rings and a section of wheel with cylindrical teeth that works the longitudinal rack. When the breech is completely closed, the lever enters breech of the gun free. To close the breech, the hand- lever is brought back. Cylindrical Breech - Block, with Repeat Firing Action (Figs. 669 to 671).—This type contains the same principal elements as the one just described; it differs from it, however, in this detail, that during the opening and closing actions, the breech-block is not shifted with relation to tbe seating, the swinging of the mechanism to the side taking place immediately after unscrewing. The block is cylindrical, with two threaded parts and two interruptions; a screwed cylindrical part is cut out centrally in the rear, thus forming a toothed socket for a pivot of equal diameter carried by the breech- Fig. 664. Fig. 665. Figs. 664 to 668. Single-Motion Breech-Mechanism, with Repeating Firing Device. a notch in the rear, and presses down a tongue spring which secures the system, and prevents the accidentai opening of the breech. The firing device is repeating, and embodies the general arrangements previously described with the two-motion breech-blocks, and also their safety appliances. To open the breech, it is sufficient to turn the hand-lever round in a horizontal plane. During the first period, the endless screw arrangement acts on the toothed wheel, and causes the breech-block to revolve. In the second period, the cylindrical teeth of the pinion engage the rack, and eflfect the withdrawal of tlie breech- screw. The continuée! action of the hand-lever brings the whole of the mechanism to the side, leaving the screw and the support. On the right the block is fitted with a toothed wheel arrangement, of the same type as that described for the preceding breech-piece ; the seating is cut in such a way that the block can enter the gun simply by bringing round the hand-lever, no shifting aetion being necessary. The breech-block support is in the form of a disc ; it completely closes the gun in the rear, and affords, in conséquence, full protection for the varions parts of the mechanism. It pivots round a vertical hinge fitted to the right of the breech-end, and carries the block through the screwed socket and pivot mentioned above. It carries also on the right, the socket for the endless screw, which works the pinion that forms part of the breech-screw,