GB191302464A - Breech Mechanism with Knuckle Joint for Automatic Fire-arms having Stationary Barrels. - Google Patents

Abstract

2464. Schwarzlose, A. W. Jan. 30. Breech actions, sliding breech-block; breech actions, hinged breechblock.-Relates to automatic guns having a toggle-link action, and consists in arranging the front link to form. the breech - block. In the construction shown in Figs. 1 and 2, the front link s is jointed to a sliding block v, s h o w n separately in Fig. 2, by curved ribs v<2> and grooves s<3>. The ribs and grooves are so arranged that the axis of rotation c is above the base of the cartridge, thus, on the discharge, the gas pressure causes the front link to swing upwards. The front surface of the link s is smaller than the base of the cartridge, which, after a short rearward movement, is caught by a flange v<4> in the guide head v. In the modification shown in Figs. 4, 5, 6, 7, and 8, the sliding guide-block is replaced by two sliding plates w on which the bridge-shaped extractor a is mounted. The rear link g has two axes of rotation which successively come into operation, thus delaying the opening of the breech. The first axis I is formed by a rearward extension g<1> on the link and a bearing-surface h<3> on the breech frame ; the second axis II is formed by the pivot pin d, which is loosely mounted in its bearing to allow of the action of the first fulcrum during the initial bending movement of the toggle. To give greater force to the initial extracting movement, a nose s' on the front link s engages a shoulder h<2> on the frame, the point of contact forming a momentary axis of rotation. The hinge pin b, Fig. 9, connecting the two links has its central part b engaging the rear link, eccentric with regard to the outer parts b', b<4> which are mounted in the front link. By rotating this pin through 180 degrees, the hinge of the toggle may be lowered to such an extent that the gun no longer opens automatically. This eccentric pin can also be used to take up wear. In Figs. 10 and 12 is shown a construction specially suited for machine guns. The rear link g is constructed with two fulcrums as described in the previous modification. The front link also is arranged to have two axes of rotation. This is attained by the following construction. The front link is hinged to side plates w by studs v<4> so positioned that the axis of rotation is behind the base of the cartridge. On the front link is a nose s<9> which, during the final closing movement, engages under abutments h<5> and forces the link and guide-plates downwards to produce a slight clearance between the top of the plates and the breech casing. Thus the initial opening movement is about the nose s<9>, and subsequent movement about the axis c<1> of the studs v<4>. The nose s<9> also acts to eject the cartridge case by giving its rear end a downward blow. One of the guide-plates w is provided with an inward claw for an extractor. The cartridge case is loosened, as in the previous modification, by a nose s<8> on the front link striking a shoulder h<2> on the frame. The packing-ring r of the water jacket is placed in such a position that the water can circulate up to the breech opening.