Abstract:
The invention relates to a breech for a repeating rifle with a lock guide, a bolt head arranged in the lock guide, a locking sleeve arranged concentrically with the bolt head with several locking elements that can be moved by an expansion device between an inner unlocked position and an outer locked position, and a locking lever that is arranged in the lock guide and that can be activated by means of a bolt handle with which is associated a first cam element that is arranged so that it can rotate in the lock guide with a rear contact surface for support against a fixed control element. To allow especially smooth-running and safe locking action, a second cam element, which can rotate independently of the first cam element and that has a rear control cam for support against the fixed control element is associated with the locking lever.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 U.S.C. §119 to German Patent Application No. 10 2008 027 709.6 filed Jun. 11, 2008, the entire contents of which are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to a breech for a repeating rifle. The invention also relates to a receiver for such a breech. 
     BACKGROUND OF THE INVENTION 
     A breech of a repeating rifle of this type is known from DE 43 05 700 C1. In that document, a bolt head and a locking sleeve arranged concentrically about this bolt head are arranged within a locking guide that is displaceable on a receiver. The locking sleeve constructed as an expansion sleeve is divided at its front end into several flexible spring tongues by longitudinal slots. The spring tongues have locking elements at their front ends for engaging in an annular groove on the inside of the barrel. By means of an expansion cone provided on the bolt head, the locking elements constructed integrally with the spring tongues of the locking sleeve can move between a radially inner unlocked position and a radially outer locked position. For this known breech, the advance of the lock guide that is displaceably arranged on a receiver is controlled by an individual cam element arranged so that it can rotate in the lock guide. 
     SUMMARY OF THE INVENTION 
     The task of the invention is to create a breech for a repeating rifle and an associated receiver that permit an especially smooth-running and reliable bolt action. 
     This task is achieved by a breech as set forth below and by an associated receiver as also set forth below. 
     Preferred improvements and advantageous embodiments of the invention are also set forth below. 
     In the breech according to the invention, the displacement of the lock guide relative to the receiver necessary for activating the breech is achieved by two cam elements led alternately into engagement with a fixed control element. By means of the first cam element, safe locking of the breech can be guaranteed with high force transmission, while by means of the second cam element, through the additional control cam provided there, the axial displacement needed for the insertion of the bolt head into the barrel is also achieved with a small pivoting motion of the locking lever. The first cam element is constructed such that it provides, by means of corresponding lever ratios, good force transmission when the locking sleeve is expanded for moving the locking elements into the locked position. In contrast, the shape of the second cam element with the additional control cam is selected so that, just through a small rotation of the locking lever, a comparatively large axial displacement of the lock guide relative to the receiver can be generated. By dividing the advancement onto two separate cam elements, a uniform advance motion is enabled with low expenditure of force. 
     In one construction that is advantageous with respect to structure and production, the two cam elements are supported so that they can rotate freely on a common transverse shaft arranged in the lock guide. 
     The two cam elements preferably each have a rear control shoulder for engaging with control surfaces on the fixed control element and a front catch tab for engaging with the locking lever. 
     The expansion device for moving the locking elements between the inner unlocked position and the outer locked position is made, in a preferred construction, from a support sleeve that is connected by means of a shoulder to the locking lever and that is led, with a front end in contact with ramp beveling, onto spring tongues of the locking sleeve formed as an expansion sleeve and supports the locking elements in the locked position over a large surface area. In this way, a particularly stable and safe locking is achieved. 
     The receiver belonging to the breech contains side guide grooves for the displaceable guidance of a lock guide of the breech, wherein there are two control surfaces on the receiver for engaging with the two cam elements arranged one next to the other in the lock guide for activation of the breech. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       Other special features and advantages of the invention emerge from the following description of a preferred embodiment with reference to the drawing. Shown are: 
         FIG. 1 : the rear part of a barrel and a locked breech of a repeating rifle in a longitudinal section, 
         FIG. 2 : a part of a receiver of a repeating rifle in a perspective view from the rear, 
         FIG. 3 : a part of the receiver of  FIG. 2  in a perspective view from the front, 
         FIG. 4 : the front region of a bolt head of the breech shown in  FIG. 1  in an enlarged partial view, 
         FIG. 5 : a locking lever with cam elements of the breech shown in  FIG. 1  in a perspective view, 
         FIGS. 6   a ,  6   b : the breech of  FIG. 1  shortly before the unlatching of the cam elements on the locking lever, 
         FIGS. 7   a ,  7   b : the breech of  FIG. 1  during the advancement by the cam elements, 
         FIGS. 8   a ,  8   b : the breech of  FIG. 1  shortly before the expansion of the locking sleeve by the support sleeve, 
         FIGS. 9   a ,  9   b : the breech of  FIG. 1  at the beginning of the expansion of the locking sleeve by the support sleeve, 
         FIGS. 10   a ,  10   b : the breech of  FIG. 1  in the locked position, 
         FIGS. 11   a ,  11   b : the breech of  FIG. 1  at the beginning of the opening process, and 
         FIGS. 12   a ,  12   b : the breech during the opening process with a still locked locking sleeve. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In  FIG. 1 , the rear part of a barrel  1  and a breech  2  of a repeating rifle in a locked position are shown. On its rear end, the barrel  1  has a cartridge holder  3  and a locking head  4  with a locking groove  5  on the inner wall of a receiving hole  6 . 
     The breech  2  contains a lock guide  7  that is constructed as a slide and that is guided so that it can move on a receiver  8  shown partially in  FIGS. 2 and 3  by means of side longitudinal guides  9 . The breech  2  further contains a locking sleeve  10  that is constructed here as an expansion sleeve and that is arranged in a hole  11  expanded frontwards with a step shape in the lock guide  7  and that contains, at its front part, several spring tongues  12  divided by longitudinal slots. At their front end, the spring tongues  12  have locking elements  13  in the form of thicker sections for engaging in the locking groove  5  of the barrel  1 . 
     The locking sleeve  10  is fixed in the axial direction by a safety piece constructed as a chamber holder  14  within the lock guide  7 . Within the locking sleeve  10 , a support sleeve  15  that is coaxial with this locking sleeve is guided so that it can move in the axial direction by a predetermined amount. For this purpose, the support sleeve  15  has, in the region of the chamber holder  14 , a recess  16 . The displacement of the locking sleeve  10  is limited by the dimensions of the recess  16 . Within the support sleeve  15 , the rear, narrower part  17  of an essentially cylindrical bolt head  18  is arranged coaxial with the support sleeve  15 . The rear part  17  of the bolt head  18  is thus surrounded coaxially by the locking sleeve  10 , wherein the axially displaceable support sleeve  15  is arranged between the rear part  17  of the bolt head  18  and the locking sleeve  10 . 
     The bolt head  18  further has, in addition to the narrower rear part  17 , a breech head  19  that is enlarged and projects frontwards relative to the locking sleeve  10  and the lock guide  7  for engaging in the receptacle borehole  6  of the locking head  4  at the end of the barrel  1 . In the narrower, rear part  17  of the bolt head  18  there is a side opening  20  for engaging the chamber holder  14 . The side opening  20  in the bolt head  18  is somewhat larger than the chamber holder  14 , so that the bolt head  18  can move in the axial direction by a small amount relative to the lock guide  7 . In a known way, the firing pin and an associated firing-pin spring are housed in the bolt head  18 . The firing pin and the firing pin spring are not shown because their arrangement within the bolt head  18  is known. 
     From the enlarged partial view of the front region of the bolt head  18  according to  FIG. 4  it emerges that the bolt head  18  has, on the rear side of the breech head  19  enlarged in diameter, in the transition region to the narrower rear part  17 , a conical, rear abutment surface  21  for front, cone segment-shaped contact surfaces  22  on the locking elements  13  at the end of the spring tongues  12  of the locking sleeve  10 . The spring tongues  12  contain, on the inside in the region of the transition to the locking elements  13 , inner ramp beveling  23  for spreading apart the spring tongues  12  by the support sleeve  15 . Through a forward movement of the support sleeve  15 , the spring tongues  12  could thus be spread apart and the locking elements could be moved from an unlocked position shown in  FIG. 6  into a locked position shown in  FIG. 1 . The locking elements  13  contain backwards directed, rear cone segment-shaped contact surfaces  24  that interact in the locked position shown in  FIG. 4  with a rear locking surface  25  on the rear side of the locking groove  5  in the locking head  4  of the barrel  1 . The rear locking surface  25  of the barrel  1  has, relative to the center axis  26  of the barrel  1  and the bolt head  18 , a relatively steep angle α of 70° to 80°, advantageously 75°. The rear contact surfaces  24  are constructed so that, in the locked position, these also assume the angle α and thus form a planar contact on the locking surface  25  of the barrel  1 . The conical abutment surface  21  of the bolt head  18  is inclined, relative to the center axis  26  of the barrel  1  and the bolt head  18 , by an angle β between 80° and 85°, advantageously 83°. The cone-segment-shaped, front contact surfaces of the locking elements  13  on the end of the spring tongues  12  are also inclined at the angle β to the center axis  26 . Through the steep construction of the locking surface  25  in the locking groove  5  of the barrel  1 , pressure forces F acting on the barrel  1  during the discharge of a shot by the locking elements  13  have a relatively large component Fx in the axial direction and only a relatively small component Fy in the radial direction, as shown by the arrows in  FIG. 4 . In this way, a pressure-generated expansion of the barrel end can be prevented, and thus the stability of the locking can be improved. 
     In the lock guide  7 , a locking lever  27 , shown in perspective in  FIG. 5 , is mounted so that it can rotate about an axis  28  running perpendicular to the lock guide  7 . The locking lever  27  can be activated by a bolt handle  29  and contains, on the bottom side, two parallel legs  30   a  and  30   b  that each have a backwards projecting locking shoulder  31   a  or  31   b  with a recess  32   a  or  32   b  in the bottom side. On the inside of the right leg  30   b  there is an inwards projecting shoulder  33  for the positive-fit engagement in a recess  34 , which can be seen in  FIG. 1 , in a rear projection  35  of the support sleeve  15 . On the top side, the locking lever  27  contains a tab  36  with a recess  37  in which engages a head  38 , shown in  FIG. 1 , of an unlocking pin  40  guided so that it can move in a longitudinal direction in a longitudinal hole  39  of the lock guide  7 . By means of the rear locking shoulders  31   a  and  31   b , the locking lever  27  is engaged with two cam elements  41   a  or  41   b  that are arranged one next to the other and that are arranged on a common transverse shaft  42  so that they can rotate in the lock guide  7  and receive a force in the clockwise direction from not-shown springs. The cam elements  41   a  and  41   b  constructed as cam discs each contain a front catch tab  43   a  and  43   b  for engaging the recess  32   a  or  32   b  of the locking lever  27  and a rear control shoulder  44   a  or  44   b  for engaging with control surfaces  45   a  and  45   b  on the receiver  8 . In the shown embodiment, the control surfaces  45   a  and  45   b  are formed on raised sections  46   a  and  46   b  of a control element  47  mounted on the receiver  8 . In the shown embodiment, the control element  47  is constructed as a control plate that is screwed tight on the receiver  8 . On the cam element  41   b  on the right in  FIG. 5 , another control cam  48  is provided on the rear side. Below, the function of the breech will be explained with reference to  FIGS. 6 to 12 , wherein the left cam element  41   a  is shown in each of  FIGS. 6   a  to  12   a , and the right cam element  41   b  is shown in each of  FIGS. 6   b  to  12   b.    
     In the open position of the breech  2  shown in  FIGS. 6   a  and  6   b , the bolt handle  29  is pivoted backward, by means of which the rear locking shoulders  31   a  and  31   b  of the locking lever  27  are rotated upward and the front catch tabs  43   a  and  43   b  of the cam elements  41   a  or  41   b , biased in the clockwise direction by springs, engage in the recesses  32   a  or  32   b  on the locking shoulders  31   a  and  31   b  of the locking lever  27 . However, also on only one of the locking shoulders  31   a  or  31   b , a recess  32   a  or  32   b  could be provided in which an associated catch tab  43   a  or  43   b  of the cam element  41   a  or  41   b  can engage in a locking way. Through this locking, the bolt handle  29  is blocked against rotation and the lock guide  7  can be pushed backward and frontward within the guide  9  of the receiver  8  shown in  FIG. 2  with the help of the bolt handle  29 . In the open position of the breech  2  the support sleeve  15  is located in a retracted position in which a front end  52  of the support sleeve  15  is spaced apart from the inner ramp beveling  23  on the spring tongues  12  of the locking sleeve  10 . The spring tongues  12  of the locking sleeve  10  are therefore located in an unlocked position pivoted inward. 
     When the lock guide  7  is pushed farther forward relative to the control plate  47 , fixedly arranged on the receiver  8 , past the position shown in  FIGS. 6   a  and  6   b , the two rear control shoulders  44   a  and  44   b  of the cam elements  41   a  and  41   b  according to  FIGS. 7   a  and  7   b  are lifted by the beveled control surfaces  45   a  and  45   b , by means of which the front catch tabs  43   a  and  43   b  are led out of the recesses  32   a  or  32   b  and the lock between the cam elements  41   a  and  41   b  and the locking lever  27  is released. Thus, the bolt handle  29  can be pivoted frontwards. 
     For the forward pivoting of the bolt handle  29  and the resulting rotation of the locking lever  27 , the locking shoulders  31   a  and  31   b  press onto a front, beveled surface  49   a  or  49   b  of the cam elements  41   a  and  41   b , by means of which the front catch tabs  43   a  and  43   b  according to  FIGS. 8   a  and  8   b  are pressed downward until the control cam  48  on the right cam element  41   b  according to  FIG. 8   b  is led into contact with a front edge  50   b  of the raised section  46   b . In contrast, in this position the left cam element  41   a  does not yet contact the front edge  50   a  of the raised section  46   a , as can be seen from  FIG. 8   a.    
     Through the further rotation of the locking lever  27  according to  FIGS. 9   a  and  9   b , the two cam elements  41   a  and  41   b  are further rotated by means of the contact of the locking shoulders  31   a  and  31   b  on the front surfaces  49   a  or  49   b  of the cam elements  41   a  and  41   b  until the left cam element  41   a  according to  FIG. 9   a  with a rear surface Ma is led into contact on the front edge  50   a  of the raised section  46   a . Simultaneously, the right cam element  41   b  is led out of engagement with the control plate  47 , so that the further advance of the lock guide  7  is taken over by the left cam element  41   a . In this phase, the support sleeve  15  is also pushed forward by means of the locking lever  27  until its front end  52  comes into contact with the ramp beveling  23  on the spring tongues  12  of the locking sleeve  10  constructed as an expansion sleeve. 
     If the locking lever  27  is rotated farther, due to the forward pivoting of the bolt handle  29 , into the locking position shown in  FIGS. 10   a  and  10   b , the front catch tabs  43   a  and  43   b  of the cam elements  41   a  and  41   b  are lowered farther due to the contact of the locking shoulders  31   a  and  31   b  of the locking lever  27  against the beveled, front surfaces  49   a  or  49   b  of the cam elements  41   a  and  41   b , wherein the lock guide  7  is shifted somewhat forward by the left cam element  41   a . Simultaneously, the support sleeve  15  is pushed farther forward by means of the shoulder  33 , which can be seen in  FIG. 5 , under the thicker sections  13 , so that the spring tongues  12  of the locking sleeve  10  are expanded outward and the thicker sections  13  are led into the annular groove  5  of the barrel  1 , as is shown in  FIGS. 1 and 4 . In this way, secure locking is achieved. 
     For opening the breech  2 , the bolt handle  29  is retracted and thus the locking lever  27  is rotated for raising the rear locking shoulders  31   a  and  31   b . As emerges from  FIGS. 11   a  and  11   b , the right cam element  41   b  is first rotated for lowering the control shoulder  44   b , while the left cam element  41   a  remains in the locked position and the lock guide  7  stops in the front position. Through the rotation of the locking lever  27 , the support sleeve  15  is also retracted, so that the spring tongues  12  can be moved inward again due to their elasticity. 
     For the further retraction of the bolt handle  29 , rear locking shoulders  31   a  and  31   b  of the locking lever  27  according to  FIGS. 12   a  and  12   b  are lifted farther, so that the left cam element  41   a  is also rotated. Only when the spring tongues  12  of the locking sleeve  10  are located in the radially inner unlocked position is the lock guide  7  released for displacement towards the rear. 
     When the bolt handle  29  is retracted, the upward projecting tab  36  of the locking lever is also rotated forward and presses on the head  38  of the releasing pin  40  which is shown in  FIG. 1 , and which is therefore pushed forward against the barrel  1  and assists the opening of the breech  2  when a cartridge is jammed. 
     Although specific embodiments of the invention have been disclosed, those having ordinary skill in the art will understand that changes can be made to the specific embodiments without departing from the spirit and scope of the invention. The scope of the invention is not to be restricted, therefore, to the specific embodiments, and it is intended that the appended claims cover any and all such applications, modifications, and embodiments within the scope of the present invention.