Abstract:
A cylinder retaining mechanism for a firearm includes a frame having a firing bore and a cylinder having a longitudinal bore. A yoke is pivotally connected to the frame and is operatively connected to the cylinder for selectively pivoting the cylinder between a first position in which the longitudinal bore is aligned with the firing bore, and a second position in which the longitudinal bore is not aligned with the firing bore. A biasing mechanism is housed in the frame and has an engaging portion which is selectively accommodated within an engaging cavity formed in the yoke when the cylinder is in the first position.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of U.S. Provisional Application Ser. No. 60/446,870, filed on Feb. 12, 2003, and herein incorporated by reference in its entirety. 

   FIELD OF THE INVENTION 
   This invention relates in general to a cylinder retaining mechanism, and deals more particularly with a cylinder retaining mechanism for a revolver which assures that the cylinder remains in its closed position even during, and immediately following, a discharge of a round of ammunition. 
   BACKGROUND OF THE INVENTION 
   Known revolvers employ a rotatable cylinder to selectively position one of a plurality of rounds of ammunition in opposition to the firing bore of the revolver. The cylinder is typically housed within a frame of the revolver for selective movement in or out of the frame during a loading or unloading operation. 
     FIG. 1  illustrates one example of a known revolver  10 . As shown in  FIG. 1 , the revolver  10  includes a frame  12 , a barrel  14 , an ejector rod assembly  18  and a cylinder  20  having a plurality of longitudinal bores  22  which are adapted to selectively position, in sequence, rounds of ammunition (not shown) in opposition to the firing bore of the barrel  14 . 
   A yoke stud  24  (shown in phantom) is integrally mated to the frame  12  and provides an axis of rotation to selectively pivot both the yoke  16  and the cylinder  20  from its open position, shown in  FIG. 1 , to its closed position. A spring biased ball plunger  28  is integrally mated to the yoke  16  and communicates with a ball cavity  30  (shown in phantom) formed in the body of the frame  12 . 
   While successful to a certain degree, the interaction between the spring biased ball plunger  28  and the ball cavity  30  may experience sporadic, operational complications during, and immediately following, the discharge of a round of ammunition. When a round is discharged, the forces which propel the round down the length of the barrel  14  exert a corresponding force in the opposite direction, that is, towards the rear, handgrip portion of the revolver  10 . Although the effect of this opposite force is marginal on the interconnected elements of the revolver  10 , the manufacturing tolerances inherent in the revolver  10  permit a minute amount of structural translation to occur as a result of this incident and opposite discharge force. 
   The effect of the structural translation of certain elements in the revolver  10 , as a result of the discharge of a round of ammunition and the associated manufacturing tolerances of the revolver  10 , may cause the cylinder and yoke assembly,  20 / 16 , to move slightly rearwardly, towards the handgrip portion of the revolver  10 . Referring again to  FIG. 1 , it can be seen that the rearward movement of the yoke  16  may cause the spring biased ball plunger  28  to disengage from the ball cavity  30 , thus facilitating the unintended pivoting of the cylinder  20  from its closed position, to the open position shown in  FIG. 1 . The possibility of the disengagement of the spring biased ball plunger  28  from the ball cavity  30  may increase in proportion to the age of the revolver  10 , owing to the increasing age and reduced resilience of the biasing spring, or the like, which serves to bias the ball plunger  28  into contact with the restraining ball cavity  30 . 
   It is therefore the general object of the present invention to provide a cylinder retaining mechanism which advantageously utilizes the recoil forces generated by a firearm during discharge. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a cylinder retaining mechanism for a revolver. 
   It is another object of the present invention to provide a cylinder retaining mechanism for a revolver which securely maintains the cylinder in its closed position. 
   It is another object of the present invention to provide a cylinder retaining mechanism for a revolver which securely maintains the cylinder in its closed position, even during and immediately following the discharge of a round of ammunition from the revolver. 
   It is another object of the present invention to provide a cylinder retaining mechanism for a revolver which harnesses the force from a discharged round of ammunition to assist in the maintenance of the cylinder in its closed position. 
   It is therefore an object of the present invention to provide a firearm having a frame with a firing bore and a cylinder having a longitudinal bore, the cylinder being operatively connected to the frame such that the cylinder selectively pivots between a first (closed) position in which the longitudinal bore is substantially aligned with the firing bore, and a second (open) position in which the longitudinal bore is not substantially aligned with the firing bore. A cylinder retaining mechanism is provided for selectively retaining the cylinder in the first position, and includes a biasing member that is integrally mated with the frame. The orientation of the biasing member is designed to remain static when the cylinder pivots between the first position and the second position. 
   These and other objectives of the present invention, and their preferred embodiments, shall become clear by consideration of the specification, claims and drawings taken as a whole. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  illustrates an operational portion of a known revolver. 
       FIG. 2  is a partial cross-sectional view of a revolver having a cylinder retaining mechanism, according to one embodiment of the present invention. 
       FIG. 3  is a front-side, isometric view of the stripped-down revolver shown in  FIG. 2 , including one portion of the cylinder retaining mechanism. 
       FIG. 4  is an isometric view of a yoke for use with the revolver of  FIG. 2 , comprising another portion of the cylinder retaining mechanism. 
       FIG. 5  is a backside, isometric view of the stripped-down revolver shown in  FIG. 2 , including the yoke of  FIG. 4 . 
       FIG. 6  is a front-side, isometric view of the stripped-down revolver shown in  FIG. 2 , including the yoke of  FIG. 4 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 2  is a partial cross-sectional view of a revolver  100  having a cylinder retaining mechanism according to one embodiment of the present invention. As shown in  FIG. 2 , the revolver  100  includes a frame  112 , a barrel  114 , an ejector rod assembly  116  and a cylinder  118  having a plurality of longitudinal bores  120  which are adapted to selectively position, in sequence, rounds of ammunition (not shown) in opposition to the firing bore of the barrel  114 . 
   A yoke stud  122  is integrally mated to the frame  112  and provides an axis of rotation for the yoke (not shown). A spring biased ball plunger  124  is also integrally mated to the frame  112  and comprises one element of the cylinder retaining mechanism, as will be explained in more detail later. 
   It is therefore an important aspect of the present invention that, in contrast to known revolvers, the spring biased ball plunger  124  is integrally mated to the frame  112  of the revolver  100 . By forming the spring biased ball plunger  124  in the frame  112  of the revolver  100  instead of on the yoke element, as was discussed previously, the present invention is able to constructively utilize the recoil forces resulting from the discharge of a round of ammunition to maintain the cylinder  118  in its closed position, shown in  FIG. 2 . The manner in which the spring biased ball plunger  124  accomplishes this task will become clear by a review of the subsequent drawing figures and associated discussions relating thereto. 
     FIG. 3  illustrates a stripped-down version of the frame  112  showing the spring biased ball plunger  124  and a stud recess  126 . The stud recess  126  is adapted to secure the stud  122  (shown in  FIG. 2 ) therein and provides for selective rotation of the yoke element, to be described shortly. 
   Turning now to  FIG. 4 , a yoke  128  is shown, comprising another element of the cylinder retaining mechanism of the present invention. As shown in  FIG. 4 , the yoke  128  includes a stud cavity  130  which pivotably mates with and accommodates the stud  122  (shown in  FIG. 2 ). An ejector bore  132  is also defined in the yoke  128  and provides an aperture through which the ejector rod assembly  116  (shown in  FIG. 2 ) extends, thereby operatively connecting the cylinder  118  (shown in  FIG. 2 ) to the movement of the yoke  128  as it pivots about the stud  122 . A ball cavity  134  is formed as a depression in the upper portion of the yoke  128  and is designed to selectively accommodate the spring biased ball plunger  124  (shown in  FIG. 2 ) when the yoke  128 , and the cylinder  118  (shown in  FIG. 2 ), are in their closed positions. 
   It is therefore another important aspect of the present invention that the ball cavity  134  is formed on the yoke  128  itself, rather than on the frame of the revolver  100 , in contrast to known revolver architectures. By arranging the ball cavity  134  on the yoke  128  itself, the present invention is able to constructively utilize the recoil forces resulting from the discharge of a round of ammunition to maintain the cylinder  118  (shown in  FIG. 2 ) in its closed position, with great effectiveness. 
     FIGS. 5 and 6  illustrate a rear-side view of the stripped-down frame  112  and a front-side view of the stripped-down frame  112 , respectively. As shown in  FIG. 5 , the yoke  128  integrally mates with the profile of the frame  112  when it is oriented in its closed position. In the closed position of  FIG. 5 , the rear of the spring biased ball plunger  124  can be seen, with the ball of the spring biased ball plunger  124  being securely accommodated within the hidden ball cavity  134  (shown in  FIG. 4 ) of the yoke  128  (shown in  FIG. 4 ). The ejector bore  132  is also shown in  FIG. 5  and permits an arbor portion  136  (shown in  FIG. 6 ) of the ejector rod assembly  116  (shown in  FIG. 2 ) to pass therethrough, upon which the cylinder  118  (shown in  FIG. 2 ) is rotatably supported. 
   Operation of the cylinder retaining mechanism will now be explained in conjunction with  FIGS. 2–6  in combination. When the cylinder  118  of the revolver  100  is in its closed position, shown in  FIG. 2 , the cylinder  118  may be indexed in a known manner to position one of the plurality of longitudinal bores  120  opposite the firing bore of the barrel  114 . Upon actuation of an unillustrated trigger assembly, the discharge of a round of ammunition from the longitudinal bores  120  is initiated. The forces which propel the round down the length of the barrel  114  exert corresponding recoil forces in the opposite direction, that is, towards the rear, handgrip portion of the revolver  100 . As discussed previously in connection with known revolver architectures, although the effect of this opposite force is marginal on the interconnected elements of the revolver  100 , the manufacturing tolerances inherent in the revolver  100  may permit a minute amount of structural translation to occur as a result of this incident and opposite discharge force. 
   The effect of this discharge recoil force may cause the cylinder and yoke assembly,  118 / 128 , to move slightly rearwardly, towards the handgrip portion of the revolver  100 . In contrast to known revolver architectures, however, it can be seen that the rearward movement of the yoke  128  of the present invention will cause the ball cavity  134  to move farther in the engaging direction, towards the spring biased ball plunger  124 . Thus, the interconnectivity of the spring biased ball plunger  124  and the ball cavity  134  is increased during and immediately following the discharge of a round of ammunition. 
   It is therefore another important aspect of the present invention that the recoil forces which result from a discharge of a round of ammunition are constructively utilized by the revolver  100  to maintain the cylinder in its closed position. That is, as compared to known revolver architectures, any backwards, translational movement of integral elements of the revolver  100  actually reinforces the mating between the yoke  128  and the spring biased ball plunger  124 . 
   While the ball cavity  134  has been described as being formed on the upper portion of the yoke  128 , the present invention is not limited in this regard as the ball cavity  134  may alternatively be formed anywhere on the yoke  128  provided that the spring biased ball plunger  124  nests within the ball cavity  134  when the yoke  128  and the cylinder  118  have been pivoted to their closed positions. Indeed, it will be readily appreciated that the structural configuration and orientation of the ball cavity  134  and the spring biased ball plunger  124  is but one expression of a primary objective of the present invention to constructively utilize the discharge force to assist in maintaining the cylinder  118  in its closed position during, and immediately following, the discharge of a round of ammunition. 
   It will also be readily appreciated that although a spring biased ball plunger  124  has been described, alternative biasing devices apart from springs, and alternative elements apart from substantially spherical, ball-shaped structures may be substituted therefor without departing from the broader aspects of the present invention. Moreover, the present invention equally contemplates that the cylinder retaining mechanism shown in  FIGS. 2–6  may be utilized alone, or in conjunction with other, known cylinder retaining mechanisms. 
   While the invention has been described with reference to the preferred embodiments, it will be understood by those skilled in the art that various obvious changes may be made, and equivalents may be substituted for elements thereof, without departing from the essential scope of the present invention. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but that the invention includes all equivalent embodiments.