Recoil block or brake for a linear breech mechanism in an automatic fire arm

A recoil brake or block mechanism for an automatic fire arm having a linearly reciprocating breech block. This mechanism includes a slide which is reciprocally mounted on the breech block. A two-armed lever is pivotally mounted in the housing of the fire arm and is adapted to coact with the slide so as to absorb a portion of the recoil energy. The slide has front and rear contacting surfaces and the two-armed lever has a pair of arms, each of which has a control surface which is adapted to respectively coact with one of said contacting surfaces. The center of gravity of the two-armed lever is located in the longer arm of the two-armed lever at a distance from its pivot support.

BACKGROUND OF THE INVENTION 
The subject matter of this invention is related to the disclosure of German 
published patent Application No. 1,119,726 and serves to prevent a 
premature unblocking, for example, during an ignition delay. The 
arrangement includes a spring-loaded recoil arresting lever in a breech 
body for purposes of coacting with a blocking head. There is also, axially 
slidably disposed in the breech body a blocking slider and a 
blocking-weight; a coil spring is arranged between the latter two. This 
prior art arrangement requires a large amount of coaction of predetermined 
parts, which must be coordinated in accordance with their mass and the 
frictional forces which occur between non-locking, non-irreversible stop 
surfaces in accordance with the forces exerted by the corresponding spring 
and in accordance with the corresponding intertia moments of the various 
parts. The large number of individual parts has been found to be 
disadvantageous, because they constitute a complex constructional assembly 
and, in view of the high velocity and acceleration, to which the assembly 
is exposed, constitutes not only a very large assembled mass, which is a 
drawback, but also such complex construction produces significant 
malfunctionings. 
SUMMARY OF THE INVENTION 
It is the object of this invention to provide a recoil blocking arrangement 
of the aforedescribed type wherein the drawbacks mentioned hereinabove are 
avoided and which is of simple construction, reliable and is inexpensively 
manufactured. 
According to the present invention there is provided an automatic fire arm 
which has a firing-pin-carrying slide. This slide is adapted to lock the 
breech when in a forward limit position thereof, wherein a two-armed lever 
is provided rotatable about an axis relative to the fire arm alternatively 
to position abutment surfaces on opposite sides of said axis in the path 
of abutment surfaces of said slide, the arrangement being such that 
immediately before the slide reaches said forward limit position thereof a 
first of said abutment surfaces of the slide will contact a first of said 
abutment surfaces of the two-armed lever to deflect the same so that a 
second of said abutment surfaces of the two-armed lever is positioned to 
intercept a second of said abutment surfaces of the slide when the latter 
recoils from said foward limit position thereof. 
Each of said abutment surfaces is preferably inclined with respect to the 
plane of reciprocative movement of the slide. 
Said first of said abutment surfaces of the two-armed lever is preferably 
the rear surface of an upward projection at the free end of a shorter 
leading arm of the lever and said second of said abutment surfaces of the 
lever is preferably the leading edge of an upwardly-bent free end portion 
of a longer, rearwardly-extending arm of the lever, the center of gravity 
of the lever being spaced from said rotational axis thereof along said 
longer arm so that in a normal attitude of the fire arm the lever is 
biased by gravity to a position wherein said first abutment surface of the 
lever is not in the path of the slide. 
The rear edge of said free end portion of the longer arm of the lever 
preferably constitutes a third abutment surface of the lever inclined with 
respect to the plane of reciprocative movement of the slide, the 
arrangement being such that if as the slide moves forward from a fully 
retracted position thereof said third abutment surface of the lever is in 
its path the latter will be deflected by said first abutment surface of 
the slide so as to position said first abutment surface of the lever in 
the path of the slide. 
The rotational movement of the lever about its axis is preferably limited 
by the location of a forward projection of the lever within a cavity in 
the fire arm. 
The slide is preferably mounted on a carrier therefore for limited 
reciprocative movement relative thereto and for reciprocative movement 
therewith relative to a fixed part of the fire arm in which the lever is 
rotatably mounted, the said abutment surfaces of the slide being the 
opposite end surfaces of an axially elongated guide projecting through and 
below the carrier below the surface of said fixed part on which the 
carrier is movable and above which opposite ends of the lever are 
alternatively raisable.

DETAILED DESCRIPTION 
In the accompanying drawing all but the relevant components of the firearm 
have been omitted for sake of clarity, but it is to be understood that 
except for the mechanism for retarding the recoil firing-pin-slide it 
generally belongs to the state of the art as examplified by disclosure of 
German Pat. No. 111 97 26. 
A breech block 10 of a straight-line slidable breech block mechanism of an 
automatic fire arm is arranged so that its forward path 80 in the 
direction of the arrow 80.V and its recoil path in the direction of the 
arrow 80.R are illustrated in FIGS. 1 and 2. The breech block 10 has an 
axially slidable blocking slide 20 mounted thereon which is provided with 
a bore 24 for accommodating a striker bolt or firing pin 26 therein. An 
entraining or abutment surface 12 on the breech block 10 coacts with the 
rear contacting abutment surface 22 of the blocking slide 20; between 
those two surfaces a maximum distance d is provided for producing the 
blocking illustrated in FIG. 2. On its underside the blocking slide 20 has 
a strip-shaped projection 28 having a frontal control abutment surface 30 
and a rear control abutment surface 32. Both control surfaces 30, 32 are 
inclined at predetermined angles with respect to the path of movement 80. 
At the housing 70 the lever 40 is freely pivotally mounted about a support 
shaft 42 in a region 44. A first lever arm 46 has a first nose 48 provided 
with a control abutment surface 50. A second nose 52 of the lever arm 46 
is defined from below by means of an exterior surface 54 of the lever arm 
46 and from above by means of contacting abutment surface 55. A second 
lever arm 56 has a free end 58 which is inclined with respect to the path 
of movement 80; this free end 56 has a forwardly inclined abutment surface 
60 and a rearwardly inclined abutment surface 62 and a connecting surface 
64 disposed between the inclined surfaces 60 and 62 and an under-exterior 
surface 68. The center of gravity 66 of the lever 40 is disposed outside 
of the pivot support region 44 on the lever arm 56. In the housing 70 
there is provided an upper limit surface 72 adapted to coact with the 
contacting surface 55 and a lower limit surface 74 adapted to coact with 
the exterior surface 54. In view of its free pivotal mounting and also in 
view of the location of its center of gravity, the two-armed lever 40 is 
positioned so that the first lever arm 46 projects with its nose 48 into 
the path of movement 80. It bears thereby with its contacting surface 55 
against the upper limit surface 72. 
The functioning of the recoil blocking mechanism of the invention is as 
follows: In the firing path the breech block 10 moves in the direction of 
the arrow 80.V until it reaches the position illustrated in FIG. 1 in 
which it is arrested. Due to its moment of inertia, the blocking slide 20 
continues to move forwardly axially relative to the breech block 10 in the 
direction of the arrow v and arrives in a forward region of its path of 
movement 80 in which it is rigidly held by the non-illustrated blocking 
element (blocking region, wherefrom the blocking condition results). 
Immediately prior to reaching its most forward end position, the blocking 
slide 20 contacts, with its forward control surface 30, which is disposed 
on the underside projecting strip 28, the control surface 50 of the nose 
48 of the two-armed lever 40 which lies in the path of movement 80 (FIG. 
2). Thereby the blocking slide 20 transmits, in impulse-like fashion, a 
portion of its kinetic energy to the lever 40. Therefore, immediately 
before the slide 20 reaches its final, breech-locked position the leading 
abutment surface 30 of the projection 28 strikes the abutment surface 50 
of the lever 40. This has the advantage of decelerating the slide 20 
immediately before it reaches the breech-locking position, thus reducing 
the danger of premature rebound in the direction 80R, while at the same 
time positioning the surface 60 of the lever 40 in the path of the 
abutment surface 32 when the slide 20 recoils in the direction 80R through 
rotation of the lever 40 about the shaft 44. During the subsequent recoil 
movement of the slide 20 in the direction 80R energy is again exchanged 
between the slide 20 and the lever 40 resulting in a retardation of the 
initial movement of the slide 20 which is sufficient to prevent it from 
leaving its forward, breech-locked position until the ammunition in the 
breech has been detonated, even if detonation is delayed. This obviates 
the well-known dangers of delayed detonation occurring while the breech is 
being unlocked. The inclination of the abutment surfaces 32 and 60 ensures 
that the slide 20 is not arrested but merely retarded by the lever 40. The 
free end 58 of the arm 56 of the lever is deflected in the direction of 
the arrow f below the plane 80, causing the projection 48 on the arm 46 to 
move in the direction of the arrow s above the plane 80. 
The mechanism of the invention is advantageous in its simplicity and 
reliability. In the event that the weapon is in an unusual attitude such 
that gravity does not return the lever 40 to the position shown in FIG. 1 
abutment of the surface 30 with the surface 62 as the slide 20 moves in 
the direction 80.V will cause deflection of the lever 40 to the position 
shown in FIG. 1 where the projection 48 is positioned above the plane 80 
in the path of the surface 30 of the slide, so that as the latter reaches 
the position in which the breech is locked the arm 46 of the lever is 
deflected in the direction of the arrow a so that the arm 58 is deflected 
in the direction of the arrow h, positioning the abutment surface 60 above 
the plane 80 to intercept the abutment surface 32 when the slide 20 
recoils. 
Although the invention is illustrated and described with reference to one 
preferred embodiment thereof, it is to be expressly understood that it is 
in no way limited to the disclosure of such a preferred embodiment, but is 
capable of numerous modifications within the scope of the appended claims.