Fire limiter for automatic firearms with hammer blow detonation

In a fire limiter for automatic firearms with hammer blow detonation, a pawl (38) is supported pivotally directly on a bearing on the hammer arranged eccentrically to the latter's pivoting axis (1). The pawl transfers essentially the entire striking motion of the hammer to a wheel ratchet, which at every shot rotates by one tooth and is held in any given position by a spring-loaded stop pawl. The wheel ratchet is provided with a cam which, after a predetermined number of intermittent stops, activates a fire disconnector which preferably comprises a trip-releasing catch (26), supported pivotally on the trigger (16), and a sear (12), supported pivotally on the same shaft (14) as the trigger (16). The catch (26) initially latches the sear (12) and is pulled away from the sear (12) by the wheel ratchet, whereby the sear is released to drop into a detent (11) on the hammer (2).

FIELD OF THE INVENTION 
This invention concerns a fire limiter for automatic firearms with hammer 
blow detonation, especially hand firearms, with a wheel ratchet that at 
each shot is turned one tooth by a pawl whose movement is derived from the 
movement of the hammer, the ratchet being held in any given position by a 
spring loaded stop pawl and being provided with a control cam which after 
a predetermined number of intermittent advances activates a fire 
disconnector. 
BACKGROUND OF THE INVENTION 
Such a fire limiter is known from German Pat. No. 21 36 101. In the known 
fire limiter, the activation of the stop pawl takes place through a rod 
linked with the hammer, on which rod a compression spring loading the 
hammer is arranged. Each time, toward the end of the cocking movement of 
the hammer, the end of the rod penetrating a spring abutment, impacts on 
an arm of the pawl and thereby pivots the pawl, which drives the wheel 
ratchet with its pivoting movement. 
From German Pat. No. 12 97 002, another fire limiter for automatic firearms 
with hammer blow detonation is known, in which not a wheel ratchet, but a 
linearly movable ratchet rod is provided, which is moved by an actuating 
pawl and held in a given position by a spring-loaded stop pawl. In this 
known fire limiter, the hammer itself is engaged with the actuating pawl 
at the end of its cocking motion and transmits its motion to the motion of 
the pawl which in turn drives the ratchet rod. 
In both known fire limiters, the advance of the wheel ratchet or the 
ratchet rod takes place on the last part of the cocking motion of the 
hammer caused by the breech recoil of the firearm. Here sudden violent 
stresses appear that put a lot of strain on the fire limiter and the parts 
that work with it. Also, bouncing effects can occur that adversely affect 
the operating reliability of the fire counter. 
SUMMARY OF THE INVENTION 
The object of the invention is, therefore, so to design a fire limiter of 
the type mentioned at the beginning that the stress on it is decreased and 
its operating reliability is increased. 
This object of the invention is achieved by having a pawl remain in solid 
driven connection with the hammer and transmit essentially the entire 
motion of the hammer running in one direction to the ratchet wheel. 
The utilization of the entire hammer motion running in one direction leads 
to a considerable increase in the duration of the movement and thereby a 
significant decrease in the stepping speed, whereby excess acceleration 
and the application of excessive forces are avoided that would otherwise 
have to be produced for achieving the high accelerations. Since the 
movements do not now have to occur as suddenly and violently as before, 
there is more time for the engagement of the spring-loaded stop pawl, so 
that the spring loading of this pawl can also be decreased and its 
engagement time increased, whereby the danger of failures or errors in the 
movement travel and in the shot counting is decreased. 
In a preferred embodiment of the invention, the pawl drives the wheel 
ratchet with the striking motion of the hammer. The striking motion of the 
hammer occurs under the influence of the striker spring that loads the 
hammer and is therefore determined exclusively by the design of the 
weapon, differently from the cocking process, taking place under the 
influence of the breech recoil, which to a high degree depends on the type 
of ammunition fired. 
Therefore, in the utilization of the striking movement of the hammer an 
accurate constructional design setting as to the timing of the stepping 
action of the fire limiter during the course of the hammer movement, is 
possible, leading to the optimum operation of the fire limiter. Moreover, 
the utilization of the striking movement of the hammer also is favorable 
for the interruption of the firing, because after the forward movement of 
the fire limiter the entire return time of the breech is available to 
prepare the members controlled by the wheel ratchet for the interruption 
of the firing to catch the cocked hammer. 
The utilization of the entire movement of the hammer running in one 
direction for the forward movement of the wheel ratchet can take place in 
a simple manner by having the pawl mounted pivotally directly on a bearing 
arranged on the hammer eccentrically to its swivel axis. By means of the 
arrangement of this bearing, the magnitude and the temporal duration of 
the step motion of the pawl can be optimally adjusted to the hammer 
movement. Furthermore, in this way additional intermediary components are 
avoided that complicate the movements and increase the masses to be moved. 
The eccentric bearing can have a relatively large diameter, so that the 
forces arising in the stepping process can be absorbed over a large area. 
A particularly simple and space-saving embodiment of such a fire limiter 
can be obtained by loading the pawl and the wheel ratchet with a common 
compression spring that is arranged between two approximately parallel 
arms arranged on the pawl and on the wheel ratchet. The spring tends to 
keep the pawl engaged with the wheel ratchet and at the same time tends to 
return the wheel ratchet to its initial position. The compression spring 
can be arranged on a spring rod, articulated on the arm of the wheel 
ratchet and penetrating an opening in the arm of the pawl. 
The above-mentioned relatively low speed of the ratchet movement also makes 
it possible to effect the fire interruption in a manner which is both 
simple and especially reliable, without the necessity of any considerable 
incursions into a known trigger system that can be adjusted for single 
shot and continuous fire and has a sear working with the hammer that 
pivots on the same axis as the trigger. Even the above-mentioned known 
fire limiters work in conjunction with such a trigger system, but require 
greater incursions and particularly the provision of additional catch 
pawls. In a preferred embodiment of the fire limiter of the invention, the 
wheel ratchet for the interruption of the firing simply engages with a 
trip releasing catch, mounted pivotally in the trigger, which catch 
supports the sear pivoted on the same axis as the trigger. The ratchet 
pulls this trip-releasing catch away from the trigger lever so that the 
trigger lever is free to fall into the hammer notch provided therefor. 
Accordingly, no additional member needs to be provided that holds the 
hammer after the interruption of the firing and must be released by means 
of the trigger mechanism, but rather the directly available sear is also 
used for the interruption of the firing. The trip-releasing catch thus 
takes the place of a stationary stop for the sear hitherto provided in the 
trigger.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENT 
The trigger mechanism shown in the drawing comprises a hammer 2, supported 
on a shaft 1 in a trigger case 4. The hammer 2 is loaded by a compression 
spring 3 which abuts at one end on a wall of the trigger case 4 and at the 
other end on the forked head 5 of a rod 6. The forked head 5 is connected 
by means of a thrust bearing 7 with the hammer 2. 
After the cocking of the hammer 2 by means of the not shown breech of the 
firearm, the hammer is first latched by a catch pawl 10 having an arm 9 
which engages a detent 8 on the hammer 2. If the breech assumes the 
closure position, the catch pawl 10 is deflected in the direction of the 
arrow F, so that the arm 9 of the catch pawl 10 releases the detent 8 of 
the hammer, as shown in FIG. 1. With the trigger not activated, the hammer 
2, then, as likewise seen in FIG. 1, is held in the cocked position by a 
sear 12 having an arm 15 which engages in a detent 11 on the hammer 2. 
The sear 12 is carried in the trigger case 4 on the same shaft 14 as the 
trigger 16. The sear 12 has for its seating on the shaft 14 a slot and 
braces itself with the slot half 13, closer to the hammer, engaged against 
the bearing shaft 14, when the sear 12 is engaged with the hammer 2. In 
the sear 12 there is located a spring-loaded pin 17 which tends to move 
the trigger lever 12 in its longitudinal direction vis-a-vis the shaft in 
such a way that the other slot half 18, more remote from the hammer 2, 
comes into contact with the shaft 14. Further, the sear 12 is pressed on 
its arm 15 facing the hammer 2 by a spring-loaded roller 33 in the 
direction of the hammer 2 and held engaged with the detent 11 of the 
hammer 2 when the trigger is unactivated. 
The trigger 16, supported on the shaft 14, is loaded in clockwise direction 
by means of a not shown spring, so that an arm portion 19 of the trigger 
16 in its normal position is in contact with a stop dog 20. The trigger 16 
has a projection 21 that works in conjunction with a cam 22 on the safety 
shaft 23 supported rotationally in the trigger casing 4. Furthermore, in a 
hollow portion of the trigger 16, there is supported on a pin 25 a 
swingable trip-releasing catch 26 which is loaded in the counterclockwise 
direction by means of a spring 27. In its rest position, the 
trip-releasing catch 26 is braced with its arm 28 against a stop 31 
disposed in the trigger 16. 
In the position of the safety shaft 23 shown in FIG. 1, the weapon is 
secured. The arm 21 of the trigger 16 is in contact with the outside of 
the cam 22 and can therefore not be moved out of the position shown. 
Therefore, neither can the sear 12 be moved out of the detent 11 on the 
hammer, so that the hammer is held fast in the position shown in FIG. 1. 
By turning the safety shaft clockwise, the cam 22 can be moved to a 
greater or lesser distance out of the path of the arm 21 of the trigger 
16, thereby setting the trigger mechanism on single shot or continuous 
fire. Between the setting for single shot and continuous fire, there is 
the setting "triple shot", which is shown in FIGS. 2 to 4 and in which the 
trigger 16 can be moved so far that it comes up with its arm 19 against a 
stop 36 mounted in the trigger casing 4. 
If the trigger 16 is activated on a weapon with the safety off, upon the 
swivelling of the trigger, the sear 12 is driven by a projection 29 on the 
trip releasing catch 26. Such projection 29 comes into contact with the 
arm 34 of the sear 12. As soon as the arm 15 of the sear 12 is free from 
the detent 11 of the hammer 2, the spring-loaded pin 17 moves the trigger 
lever 12 vis-a-vis the shaft 14 and therewith vis-a-vis the trigger 16 and 
its trip-releasing catch 16, so that the lever arm 34 slides off the 
projection 29 of the trip releasing catch 26 and comes to rest on the 
shoulder 30 of the trip releasing catch. At the same time, the sear 12 
executes a clockwise pivoting which brings its arm 15 into engagement 
again with the detent 11 of the hammer 2, if the pivot angle of the 
trigger 16 is limited to its single slot position by the setting of the 
cam 22 in a manner not shown in further detail. 
In the cam setting on "triple shot" shown in FIGS. 2 to 4, however, the arm 
15 is also held out of engagement with the hammer 2 if the arm 34 of the 
sear 12 has slid off the projection 29 and lies on the shoulder 30. Now 
comes into action the fire limiter represented in FIGS. 2 to 4, which has 
a rotating wheel ratchet 39 supported concentrically to the safety shaft 
23 by means of a hollow hub 48 in the trigger casing. This wheel ratchet 
39 works together with a pawl 38 which is installed on a bearing 37 
located on the hammer 2 eccentrically to the shaft 1. The eccentricity of 
the bearing 37 is such that with each firing movement of the hammer 2, the 
wheel ratchet 39 is advanced by a ratchet tooth 40 on the pawl 38, through 
an angle corresponding to the angular extent of one of its teeth 41. The 
pawl 38 is provided with a laterally extending arm 42 which extends 
essentially parallel to an arm 45 on the wheel ratchet 39. Between these 
two arms 42 and 45 there is disposed a compression spring 44 on a spring 
rod 43. The spring rod 43 is suspended pivotally at one end on the arm 45 
of the wheel ratchet 39 and is supported slidably at its other end on the 
arm 42 of the pawl 38. The compression spring 44 exerts such torques on 
the arms of the pawl 38 and the wheel ratchet 39 that, on the one hand, 
the pawl 38 tends to engage the wheel ratchet, with the ratchet tooth 40 
of the pawl 38 between the teeth 41 of the wheel ratchet, while, on the 
other hand, the wheel ratchet 39 tends to execute a clockwise rotation. 
Also working in conjunction with the teeth 41 is a stop pawl 46 that 
likewise is pivotally supported in the trigger casing 4 on a shaft 61 and 
is loaded by a spring 62 which tends to hold the tooth 47 of the stop pawl 
46 engaged with the teeth 41 of the wheel ratchet 39. 
As already mentioned, in the case of the three-shot setting, with each 
firing movement of the hammer from the cocked position shown in FIG. 1 to 
the striking position shown in FIGS. 2 and 3, under the impetus of the 
compression spring 3, the wheel ratchet 39 is advanced one tooth each 
time. The advancing movement takes place over the entire striking movement 
of the hammer and takes place only under the accurately defined influence 
of the compression spring loading the hammer. The advance of the wheel 
ratchet takes place therefore relatively slowly and smoothly so that the 
problem-free advance of the wheel ratchet is insured with every shot. 
After a number of shots determined by the number of teeth, in the 
embodiment shown after three shots, a projection 49 on the hollow hub 48 
of the wheel ratchet 39 engages with a lateral stop 70 on the 
trip-releasing catch 26 and pivots the trip-releasing catch 26, as seen in 
FIG. 4, so far that the trip-releasing catch 26 is pulled out with its 
shoulder 30 away from the arm 34 of the sear 12, and thereby the sear 12 
is pivoted clockwise again under the effect of the springloaded roller 33 
so far that its arm 15 engages with the projection 11 of the hammer 2 if, 
after the release of the shot, the hammer 2 is cocked by the returning 
breech. Since the entire time of the shot release and the breech return 
lies between the release of the trigger lever 12 and the catching of the 
hammer 2, there is assurance that the sear 12 will reach the capture 
position at the right time and will engage securely with the hammer 2, in 
order to latch it after the completion of the desired firing cycle. 
Upon release of the trigger, as seen in FIG. 3, the extension of the 
bearing pin 25 for the trip-releasing catch 26, protruding laterally from 
the trigger 16, engages with the arms 50 and 51 of the pawl 38 and the 
stop pawl 46 and retracts these two pawls away from the wheel ratched so 
that the wheel ratchet, under the effect of the compression spring 44, can 
return to its original position in which its arm 45 is in contact with a 
stop 52. 
When the trigger is pulled again, the firing cycle, determined by the fire 
limiter, is repeated. 
As can be seen particularly from FIGS. 2 and 3, the pawl 38 has an edge 63 
which engages in a recess provided for this purpose in the safety shaft 
23. With a setting on continuous fire, the safety shaft is turned so far 
that the pawl 38 lies with its edge 63 against the outermost peripheral 
portion of the safety shaft and is thereby held out of engagement with the 
wheel ratchet 39. Therefore, the fire limiter does not come into play in 
the case of continuous fire, and the firing is interrupted only upon 
release of the trigger 16. 
It goes without saying that the invention is not limited to the described 
embodiment, but derivations from it are possible without exceeding the 
scope of the invention. Thus, for example, instead of the eccentric for 
driving the pawl, some kind of crank drive can be used, and the pawl and 
the wheel ratchet can be loaded by springs independent of each other. 
Also, the advance of the wheel ratchet could be derived from the cocking 
movement of the hammer. Finally, also the interruption of the firing could 
be effected by means of other components than the trip-releasing catch 
located in the trigger. The embodiment shown does, though, offer an 
optimum with respect to simplicity of construction, small space 
requirement and reliability.