Abstract:
A bipod for a light-weight machine gun is disclosed. The bipod has tubular telescoping legs that may be extended and retracted to discreet locking positions. The bipod has a spring-based system that allows a user to fold the bipod either towards or away from the barrel muzzle with one hand, thus giving 180 degrees of travel. The spring system also provides a detent to retain the bipod in the folded or deployed position without additional fasteners or catches. The bipod is attachable to a machine gun with a round yoke that allows the user to pivot the direction of fire and rotate the barrel of the machine gun radially while keeping the bipod firmly planted.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     REFERENCE TO A MICROFICHE APPENDIX 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to firearms, and specifically to bipods for use with a light-weight machine gun. A machine gun is not a shoulder-fired weapon like a rifle. It may be fired from the hip but is best fired when supported at the muzzle end by a bipod or other structure. Machine guns are heavy, they become quite hot when fired, and the forces associated with rapid firing makes it difficult to maintain accurate targeting unless the muzzle end is property supported. 
     A bipod has been a staple accessory for many military firearms since the beginning of firearm development. The bipod generally cradles the barrel of a firearm and has two legs that can be planted on the ground. The bipod provides stability and support for the weapon when fired, especially when fired in long bursts. 
     To be effective, a machine gun must be highly mobile and rapidly deployable. The light-weight machine gun with its bipod must be capable of being removed from one position, carried in a variety of transportation vehicles (e.g. personnel carriers, airplanes, open trucks, etc) to another position, and set up quickly, and the attached bipod should not interfere with that redepolyment. A bipod must also meet other common military objectives such as low weight, ease of use, simple construction, low cost, and high durability. 
     The twentieth century advent of the light-weight machine gun and the mechanized military has led to a refinement in the state of the art of bipods. Far from just a simple inverted V, current bipods are more complicated devices that include telescoping legs, swivel mounts, and folding structures. For example, U.S. Pat. No. 4,351,224, issued to Curtis, teaches a pair of L-shaped channels that telescope and fold from a deployed position to a stowed position. The bipod only allows for one direction of leg travel and each leg must be folded individually. U.S. Pat. No. 4,625,620, issued to Harris, teaches a pair of telescoping tubular legs that are individually folded and adjusted. In U.S. Pat. No. 5,711,103, issued to Keng, a swivel mount to incorporated into a bipod that allows a gunner to aim the weapon while keeping the bipod stationary. Keng also teaches a pair of telescoping tubular legs that are frictionally locked. 
     The prior art of firearm bipods, while extensive, is not without shortcomings. Many of the designs have many parts. One significant drawback to the prior art is that the bipod legs must be deployed separately, i.e. the legs must be unfolded one at a time rather than with a single motion. This means the user must either make two separate motions, or must set the gun down and unfold the legs with both hands. The releasing mechanisms that allow the legs to telescope and fold, such as the one disclosed by Curtis, are often overly complex, unreliable, or create a device that is somewhat unwieldy when transported in a small vehicle. Many of the designs, such as the one employing tubular legs with frictional locks as disclosed by Keng, are not suitable for military applications because they are not suitable for combat; dirt or damage to the legs can interfere with the telescoping. Therefore an improved bipod is needed that will be more robust, and easier and quicker to use than prior art bipods. 
     SUMMARY OF THE INVENTION 
     Briefly recited and according to its major aspects, the present invention is a bipod for a firearm such as a light-weight machine gun in which the telescoping legs can be deployed with one hand. The present invention has two legs that are connected by spring-based system that allows the legs to be deployed from a stowed position by applying pressure to just one leg. The legs of the present bipod may be stored facing either towards the stock of the gun or towards the muzzle. 
     When the legs are folded to a deployed position, the spring-based system acts against the legs, causing them to deploy. The spring-based system is housed inside a body that supports a yoke cradling the barrel of the gun in such a way that the gun and its yoke can be rotated radially and axially through a small angle with respect to the body. 
     Each leg can telescope incrementally between a minimum length and a maximum length, using spring-loaded buttons to lock the legs in place once the desired length is reached. However, because of the design of the buttons, the user can extend the legs simply by pulling on the end of the leg. 
     An important feature of the present invention is the spring-based system for deploying the legs. Simply rotating one leg from either stored position, pointing forward or rearward, to a direction roughly perpendicular to the stored position, cause the other leg to follow and, when rotated far enough, to spring to the deployed position where the legs are splayed instead of parallel. This feature allows very rapid deployment of the bipod with one band. 
     Another important feature is the telescoping legs that are extended by pulling and are secured in each successive greater length by the buttons. This feature also facilitates rapid deployment, and cooperates with the spring-based system for the overall speed of deployment of the bipod legs in the right length and splayed in minimal time. 
     Still another feature of the present invention is the design of the body and spring-based system that permits the legs of the bipod to be stored facing the muzzle or the stock end of the machine gun. 
     Other features and their advantages will be apparent to those skilled in the art of firearm accessory design and fabrication from a careful reading of the Detailed Description of Preferred Embodiments accompanied by the following drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings, 
     FIG. 1 is a frontal perspective top view of the bipod in the deployed position showing the legs splayed and fully retracted; 
     FIG. 2 is an exploded perspective view of the bipod in the deployed position; 
     FIG. 3A is a perspective view of the bipod in the stowed position and fully retracted; 
     FIG. 3B is a perspective view of the bipod in a deployed position with the legs retracted and showing the direction in which the legs are urged by the spring-based system; 
     FIG. 4 is a perspective view of the bipod in an alternate stowed position and fully retracted; 
     FIG. 5 is a perspective top view of the bipod yoke showing the installation on a firearm barrel (shown by phantom lines); 
     FIG. 6 is a perspective bottom view of the biped yoke. 
     FIG. 7 is a cross-sectional view taken along lines  7 — 7  of FIG.  1 . 
     FIG. 8 is a cross-sectional view taken along lines  8 — 8  of FIG.  7 . 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The preferred embodiment of the present invention is a bipod with telescoping legs that can be deployed with one hand. 
     Referring now to FIG. 1, there is shown a perspective view of a preferred embodiment of the present invention, namely, a bipod for a light-weight machine gun generally indicated by reference number  10 . Bipod  10  has two legs  12  and  14  that are attached to a body  16 . Body  16  supports a yoke  18  that is dimensioned for receiving the barrel of a firearm (see FIG. 5) such as a machine gun. 
     Bipod  10  is shown in the deployed configuration (FIG.  1 ), with legs  12  and  14  splayed to provide stability. Each leg  12 ,  14 , has a foot  22 ,  24 , respectively, that engages the ground or other surface and is preferably formed to resist lateral movement. Feet  22 ,  24 , have teeth  26 ,  28 , respectively, to bite into a surface such as the ground or a sandbag, for example, and resist lateral movement. 
     Legs  12  and  14  are telescoping, meaning that their lengths can be changed because of nested tubing that slide axially with respect to each other. Here, internal rods  34  and  36  and tubes  38  and  40  provide this telescoping capability (only one rod, rod  34 , is shown in FIGS. 1 and 2, but rod  36  is identical to rod  34 ). In particular rod  34  has an outer diameter that is smaller than the inner diameter of tube  38 , and rod  36  has a smaller diameter than inner diameter of tube  40  so that rod  34  can slide axially in and out of tube  38 , and rod  36  can slide axially in and out of tube  40 . To secure rods  34 ,  36 , with respect to tubes  38  and  40  at various relative positions, rods  34 ,  36  have spring-loaded, pivoting buttons  44 ,  46 , and tubes  38  and  40  have a series of holes  48 ,  50 , dimensioned to receive buttons  44 ,  46 . 
     Buttons  44 ,  46  will extend through holes  48 ,  50 , when in rods  34 ,  36 , bring buttons  44 ,  46 , in registration with holes  48 ,  50 , and of tubes  38 ,  40 , and, by doing so, prevent telescopic collapse of legs  12 ,  14 . However, because buttons  44 ,  46 , are spring-loaded and curved, they permit telescopic extension of legs  12 ,  14 , merely by pulling on feet  22 ,  24 . In particular, buttons  44 ,  46 , are oriented to have a major dimension parallel to the long axis of rods  34 ,  36 . Each button  44 ,  46 , has a first end  62  toward body  16  and a second end  60  oriented toward feet  22 ,  24  (only one button, button  44 , is shown exploded in FIG. 2 but button  46  is identical to button  44 ). Second end  60  is urged outward or away from the axis of rod  34  by a spring  66 . First end  62  of button  44  is free to pivot about a pin  70  oriented so that button  44  pivots about an axis perpendicular to the long dimension of rod  34 . The surface of buttons  44 ,  46  is curved so that, when feet  22 ,  24  are pulled, buttons  44 ,  46  are crammed inward, toward rods  34 ,  36 , but when feet  22 ,  24 , are pushed toward body  16 , buttons  44 ,  46 , will catch on tubes  38 ,  40  at holes  48 ,  50 , and cannot be pushed further unless pressed inward against rods  34 ,  36 , and held while feet  22 ,  24  are pushed sufficiently so that buttons  44 ,  46  go out of registration of holes  48 ,  50 . The maximum and minimum extent of telescoping of rods  34 ,  36 , with respect to tubes  38 ,  40 , is limited by stop pins  68  in slots  76  (FIGS. 3A,  3 B, and  4 ). When stop pin  68  reaches the ends of slot  76 , rods  34 ,  36 , are either completely telescopingly extended with respect to tubes  38 ,  40 , or completely telescopingly retracted. 
     Referring now to FIGS. 2,  5 - 8 , bipod  10  is attached to a firearm barrel by yoke  18 , which is ring-shaped and strong enough to provide durable support, and preferably made of metal or metal alloy. Yoke  18  is attached to a body  16  by a E-clip  52  inserted into a groove  54  in a post  56  of yoke  18  that inserts into a hole  58  of body  16  (shown in FIGS.  6  and  8 ). The connection is maintained tight enough by E-clip  52  so that yoke  18  will not wobble or vibrate, but is flexible enough to allow yoke  18  to pivot in relation to body  16 . Pivoting allows a gunner to rotate the barrel of a gun through a small angle in a plane lying perpendicular to a line bisecting the splayed legs  12 ,  14 , so that the gun carried in yoke  18  has a field of fire. The pivot angle is defined by ledges  64  on body  16  (FIG. 5) that limit the rotation of yoke  18  about post  56  (FIG.  6 ). 
     Referring in particular to FIGS. 2 and 7, in the preferred embodiment, body  16  is essentially a hollow cylinder open at both ends and having cutout portions  72 ,  74  for receiving the tops  78 ,  80 , of legs  12 ,  14 , respectively, when legs  12 ,  14 , are splayed. Legs  12 ,  14 , are held securely to body  16  by a tie member  82  that is received within body  16  but which extends far enough beyond the ends of body  16  to allow it to be inserted into slots  84 ,  86 , formed in tops  78 ,  80 , of legs  12 ,  14 , where it is secured with pins  88 ,  90 . 
     Inside body  16  is a compression spring  92  that encircles tie member  82  and is flanked by two plungers  94  (see FIG.  2  and FIG. 7) each of which is a hollow cylinder and has a cutout portion  96  for receiving tops  78 ,  80 . Compression spring  92  resists the movement of plungers  94  toward each other and urges plungers  94  axially outward of body  16 . Each plunger  94  is retained inside body  16  by pins  120 ,  121 , which also limit each plunger  94 &#39;s motion axially and rotationally through engagement with cuts  122 ,  123 , formed in the bottom of each plunger  94 . Cutout portion  96  is alignable with cutout portion  72  so that, when they are aligned, tops  78 ,  80 , will be received in both of them as legs  12 ,  14 , are rotated to a splayed position. When legs  12 ,  14 , are splayed, feet  22 ,  24 , rotate outwardly and tops  78 ,  80 , rotate into cutout portions  72 . and  96 . The plungers  94  are prevented from rotating by the engagement of pins  120 ,  121 , within cuts  122 ,  123 . 
     Meanwhile plungers  94 , urged by compression spring  92 , urges legs  12 ,  14 , to the splayed, deployed position whenever legs  12 ,  14 , are rotated from either of two stored positions. Plungers  94  accomplish this by the engagement of their leading edges  102  against legs  12 ,  14 , at points just below where pins  88 ,  90 , connect tie member  82  to legs  12 ,  14 . By applying pressure at that point, leading edges  102  of plungers  94  cause legs  12 ,  14 , to pivot about pins  88 ,  90 , to move tops  78 ,  80 , into cutout portions  72 ,  96 , but only when legs  12 ,  14 , have been rotated to the point where tops  78 ,  80  are able to be received within the aligned cutout portions  72 ,  74 , i.e., to the position where they are to be deployed. 
     When legs  12 ,  14 , have been rotated to either stowed position, tops  78 ,  80 , will not be aligned for receipt into cutout portions  72 ,  96 , and no rotation of legs  12 ,  14 , can take place. In fact, when bipod  10  is in either stored position, leading edge  102  of plunger  94  will be engaging legs  12 ,  14 , both above and below pins  88 ,  90  so no rotation will take place. Preferably, leading edge  102  of each plunger  94  has a pair of concave curves  104  formed on it (best seen in FIGS. 5,  6 , and  7 ) so that legs  12 ,  14 , are preferentially urged into the two stored positions (which will be described in more detail below). 
     FIGS. 3A,  3 B, and  4  illustrate the three positions of bipod  10 . FIG. 3A shows bipod in a stored position with the axis of yoke  18  parallel to the axes of legs  12 ,  14 . When mounted onto the barrel of a machine gun or other gun in the configuration shown in FIG. 3A with barrel pointed to the right, legs  12 ,  14 , extend rearward relative to the muzzle end of the barrel and aligned parallel to the barrel. 
     FIG. 3B illustrates bipod  10  with legs  12 ,  14  oriented with respect to yoke  18  so that legs  12 ,  14  will spring into the deployed position in which they are splayed, as indicated by the arrows in FIG. 3B, and perpendicular to that of their stored position, as shown in FIG.  5 . 
     FIG. 4 illustrates bipod  10  with yoke  18  oriented in the second of two stored positions. When bipod  10  is mounted to the barrel of a gun so that the barrel is pointed to the left, legs  12 ,  14 , will extend away from but again parallel to the barrel. The machine gun is able to fire when legs  12 ,  14 , are in any of these three orientations. 
     In use, bipod  10  is mounted to a machine gun and, if not already in one of the two stored positions, is placed in either stored positions by first pushing legs  12 ,  14 , together so that they are parallel. Then legs  12 ,  14 , can be rotated while held in parallel to either the position shown in FIG. 3A or  4  from that shown in FIG.  3 B. 
     To deploy bipod  10 , either leg  12 ,  14 , can be grasped and rotated 90° from either stored position. As leg  12  or  14  reaches the 90° point, compression spring  92  will force plungers  94  laterally and push legs  12 ,  14 , outward at feet  22 ,  24 . The user can then grasp either foot  22 ,  24 , of legs,  12 ,  14 , and pull to extend the length of that leg. At intervals along the length of legs  12 ,  14  as they are being telescopingly extended, buttons  44 ,  46 , on rods  34 ,  36 , will come into registration with holes  48 ,  50  in tubes  38 ,  40 , so that they will extend through holes  48 ,  50 . If feet  22 ,  24 , are pulled farther, buttons  44 ,  46 , will be crammed against rods  34 ,  36 , by tubes  38 ,  40 , to allowed additional length, until the desired lengths for legs  12 ,  14 , are reached and buttons  44 , 46 , have again come into registration with another set of holes  48 ,  50 . 
     Once bipod  10  is in the deployed position, the machine gun on which it is mounted can be placed in position and the gunner can check his or her field of fire by rotating yoke  18  through the angle permitted by ledges  64  on body  16 . He can also rotate the machine gun axially through the angle permitted by ledges  110  on yoke  18 . 
     It will be readily apparent to those skilled in the art of firearm accessory design and fabrication that many changes and substitutions can be made to the foregoing preferred embodiments without departing from the spirit and scope of the present invention, defined by the appended claims.