Patent Publication Number: US-6698125-B2

Title: Firearm safety mechanism with trigger facilitated retracting transfer bar

Description:
BACKGROUND 
     1. Field of the Invention 
     The present invention relates to firearm mechanisms employed in firearms utilizing a hammer and a firing pin, and in particular, to a firearm mechanism having an transfer bar between the hammer and the firing pin that is held in place by the trigger when the trigger is actuated, wherein the firearm mechanism is capable of facilitating the relocation of the transfer bar from an extended position to a retracted position upon the deactivation or release of the trigger. 
     2. Background 
     In an effort to improve upon the efficiency of firearms, devices have been introduced which require the presence of a transfer bar between the hammer and the firing pin to transfer the kinetic energy from the hammer to the firing pin. For example, in U.S. Pat. No. 566,393 to Fyrberg, the rearward motion of the trigger causes the release of the hammer which moves a pawl upward so as to bring the end of the pawl in the path of the hammer between the hammer face and the firing pin. These devices are typically in a retracted position until the hammer is fully cocked. If the device is not extended, the face of the hammer presents a space into which the head of the firing pin is received without effecting contact with the firing pin. When the transfer bar is in an extended position, the hammer face strikes the transfer bar and impact is carried through to the firing pin causing the cartridge to discharge. This transfer bar, or trigger bar, is mechanically elevated and is maintained in that elevated position through physical attachment to the trigger. 
     As a result, the weight of the trigger bar or analogous safety method must be overcome by rearward pressure on the trigger. This increased pressure on the trigger results in a reduction in accuracy. This is especially felt in light-weight firearms such as hand guns and firearms used in competition. After actuation of the trigger, the device is then maintained in the elevated position by a continued rearward pressure on the trigger as the hammer strikes the firing pin. 
     Release of the trigger allows the device to retract and the firing pin then extends into a recess in the hammer. This recess protects the firing pin from inadvertent impact when carrying the firearm. 
     Improvements to these types of safety mechanisms have been made, which allow the transfer bar weight to be borne by means other than the trigger. For example, U.S. Pat. No. 5,664,356 to Pantuso et al. describes a safety mechanism wherein the hammer has an elongated, vertically extending recess formed therein, a transfer bar traveling within that elongated recess between an extended position and a retracted position. When the transfer bar is in the extended position, the bar is interposed between the hammer and the firing pin allowing discharge of a cartridge within the chamber. When the transfer bar is in the retracted position, a portion of the recess is exposed. The exposed recess is larger than the portion of the firing pin, which protrudes from the receiver. Thus, inadvertent firing is prevented as the hammer cannot contact the firing pin. A means for positioning, preferably a transfer bar carrier pin, located on the hand assembly initially cooperates with the trigger cam and the transfer bar to elevate the bar into the extended position. The weight of the safety mechanism is, therefore, not borne by the trigger, when the hammer is in the full cock position, but by the means for positioning, thus resulting in a lighter and more accurate trigger pull. After the trigger has been fully actuated, the transfer bar carrier drops with the hand mechanism and a cam on the trigger maintains the transfer bar in the extended position. Thus, when the trigger is fully actuated, and the hammer is moving forward, the means for positioning drops away. The trigger must remain in the fully actuated position until the hammer and transfer bar impact the firing pin. If the trigger is maintained in the fully actuated position, the support of the transfer bar is shifted from the means for positioning to the trigger. Thus, the trigger must be actuated and must be maintained in the fully actuated position for the firearm to discharge. Premature release of the trigger will allow the transfer bar to drop and the firing pin will not be struck. 
     SUMMARY OF THE INVENTION 
     In accordance with the invention as embodied and broadly described herein a firearm mechanism with an improved trigger pull is provided wherein the weight of the mechanism is not on the trigger when the hammer is in the “full cock” position. The advancement presented in the present invention serves to separate the trigger from the trigger bar during the period when the trigger is pulled. As a result, the weight of the safety mechanism is not borne by the trigger while the hammer is fully cocked. This is accomplished by providing means for positioning the transfer bar into the extended position free from contact with the trigger. As the hammer is cocked, the weight of the transfer bar is borne by the means for positioning. When the trigger is fully actuated, and the hammer is moving forward, the means for positioning drops away. If the trigger is maintained in the fully actuated position, the support of the transfer bar is shifted from the means for positioning to the trigger. Thus, the trigger must be actuated and must be maintained in the fully actuated position for the firearm to discharge. 
     In addition, to increase the efficiency of the safety mechanism described herein, the present invention further features means for facilitating the retraction of the transfer bar from its extended position to a retracted position. 
     The mechanism preferably is for use with a firearm having a hammer, a cartridge receiving chamber in front of the hammer, a firing pin interposed between a face of the hammer and the cartridge receiving chamber so as to strike and fire a cartridge in the chamber upon actuation by a trigger. The mechanism comprises the following elements: a) an elongated recess formed within the face of the hammer; b) an elongated transfer bar disposed within the recess and slidably movable therein between an extended position and a retracted position, the elongated transfer bar being interposed between the hammer and the firing pin in the extended position, as well as the elongated transfer bar being juxtaposed to the firing pin in the retracted position, thereby exposing a portion of the recess capable of receiving the firing pin therein, and thereby preventing contact with the hammer; c) means, independent of the trigger, for positioning the transfer bar into the extended position and the retracted position; d) a trigger cam operated upon by the trigger, the trigger cam being capable of supporting the transfer bar to maintain the transfer bar in the extended position after the trigger has been actuated; and e) means, dependent upon the trigger, for facilitating the relocation of the transfer bar from its extended position into its retracted position upon the release of the trigger subsequent to discharge of the firearm and when the hammer is in its hammer down, safe position. 
     In a preferred embodiment, the means for facilitating the relocation of the transfer bar comprises an engagement assembly, wherein the engagement assembly itself comprises: a) a receiving member; and b) an engagement member capable of releasably coupling the receiving member, wherein the receiving member and the engagement member may be positioned on either of the transfer bar and the trigger cam. 
     The receiving member preferably comprises a protrusion extending from and integrated with one end of the transfer bar proximate the trigger, and the engagement member preferably comprises a hook extending from and extension integrated and formed with the trigger cam of the trigger. 
     As the action tracks through its cycle and the trigger actuated and released, the engagement assembly disengages and engages, respectively. Only in the hammer down, safe position may the engagement assembly be engaged to facilitate the retraction of the transfer bar into its retracted position. Upon drawing the hammer back, the engagement assembly disengages, but the receiving member and the engagement members maintain their alignment with one another. Once the trigger is actuated and the firearm is discharged, the engagement member is brought into position to couple the receiving member. However, the engagement assembly only facilitates the retraction of the transfer bar upon release of the trigger. As the trigger begins its release, the engagement assembly facilitates the retraction of the transfer bar by pulling the transfer bar down. The engagement assembly is dependent upon the trigger as the receiving member is formed as part of the transfer bar and the engagement member is formed as part of the trigger. As the trigger reaches its resting position, the transfer bar is completely retracted, thus enabling the firing pin to be biased outward into the recess where the action will be ready to be cycled once again. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other objects and features of the present invention will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only typical embodiments of the invention and are, therefore, not to be considered limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
     FIG. 1 illustrates a cross-sectional, elevational view of a firearm embodying the instant invention and demonstrating the relative position of the components of the action in the “hammer-down, safe” position; 
     FIG. 2 illustrates an action like that shown in FIG. 1, demonstrating the relative position of the components of the action in the “half-cock, loading” position; 
     FIG. 3 illustrates a cross-sectional, elevational view of the action like that shown in FIGS. 1 and 2, demonstrating the relative position of the components in the “full-cock, ready to fire,” position; and 
     FIG. 4 illustrates an action shown like that in FIGS. 1 through 3, demonstrating the relative position of the components in the “hammer down, fired” position; 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     It will be readily understood that the components of the present invention, as generally described and illustrated in the figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the system and method of the present invention, and represented in FIGS. 1 through 4, is not intended to limit the scope of the invention, as claimed, but is merely representative of the presently preferred embodiments of the invention. 
     The presently preferred embodiments of the invention will be best understood by reference to the drawings wherein like parts are designated by like numerals throughout. 
     Reference is now made to FIGS. 1 through 4 in which a firearm action is illustrated in cross-sectional detail. Although the present invention may be utilized with other firearms having a hammer, for ease of explanation, a single action revolver is depicted in FIGS. 1 through 4. Similarly, the instant invention can not only be used in new guns, but may also be retrofit into existing actions by modifying or replacing only a few components. 
     Referring now to FIG. 1, an action shown generally as  12  is depicted having a hammer  14 , a trigger  16 , a hand  18 , and a cylinder lock  20 . The action in FIG. 1 is in a “hammer down, safe” position, which is typically utilized when carrying the firearm. This is called the safe position because hammer  14  is resting against the back of receiver  24  and is therefore incapable of forward movement. An elongated vertically extending recess  26  is formed within a face  28  of hammer  14 . Firing pin  22  is shown disposed within that recess. As firing pin  22  is within recess and is not in contact with hammer  14 , firing pin  22  is protected from inadvertent impact. Also located within recess  26  is a transfer bar  30 . Transfer bar  30  slides within recess  26  between an extended position and a retracted position. Transfer bar  30  is shown juxtaposed to firing pin  22  in the retracted position in FIG.  1 . When transfer bar  30  is in the retracted position, firing pin  22  cannot be impacted by hammer  14 . Also, if the trigger is pulled, the transfer bar cannot move to the extended position due to interference with the firing pin. 
     In order for a cartridge in a chamber of the firearm to be discharged, the kinetic energy from the release of hammer  14  must be transferred through transfer bar  30  to firing pin  22 . An inadvertent release of hammer  14  when transfer bar  30  is in the retracted position results in the hammer  14  impacting receiver  24  and not firing pin  22 . Firing pin  22  will be prevented from being impacted by hammer  14  as the firing pin will be protected in recess  26  and transfer bar  30  will be in the retracted position. 
     It will be understood that the firing pin may be designed for both center fire or rim fire cartridges. 
     A cylinder  32  is shown locked into position by a lug  34  located on cylinder lock  20 . Lug  34  is biased into position in one of several notches  36  to lock the cylinder into position. Activated by trigger  16  is a cam  38 . In the depicted embodiment, the cam  38  is formed integral with the trigger, however, the only structural limitation imposed is that the trigger must activate the cam  38 . Also shown is transfer bar cam  40  formed integral with transfer bar  30 . In this hammer down position, the top face of cam  38  is not in contact with a transfer bar cam  40  located at the bottom of transfer bar  30 . Instead, transfer bar cam  40  is supported by a means for positioning the transfer bar into the extended position and the retracted position. In an embodiment illustrated in FIG. 1, the means for positioning the transfer bar is a transfer bar carrier pin  42 . Carrier pin  42  maintains the weight of the transfer bar when the trigger is being actuated. 
     FIG. 1 further illustrates means for facilitating the relocation or re-positioning of transfer bar  30  from an extended position, where the firearm may be discharged through contact of hammer  14  with firing pin  22 , to a retracted position, where the firearm is protected from discharge as firing pin  22  is protected within recess  26 . To ensure proper operation of the safety mechanism of the present invention, transfer bar  30  must be relocated to its retracted position upon the release of trigger  16  subsequent to the discharge of the firearm and when the action, and particularly hammer  14 , is in its hammer down, safe position. Relocation of transfer bar  30  to a retracted position allows firing pin  22  to properly align and be protected within recess  26  as explained above. The specific function of the means for facilitating is to assist the other components of the safety mechanism in relocating transfer bar  30  to its retracted position within recess  26  upon the release of trigger  16  subsequent to discharge of the firearm. As such, the function of means for relocating is dependent upon trigger  16  and its ability to couple or engage and interact with transfer bar  30  to perform the intended function. 
     In the embodiment shown here, means for facilitating comprises an engagement assembly  60  capable of engaging and coupling trigger  16  with transfer bar  30 . Engagement assembly  60  is designed to work in conjunction with other components to ensure correct, efficient operation of the safety mechanism of the firearm. Specifically, engagement assembly  60  itself comprises a receiving member  64 , shown as a protrusion member machined out of and integrally formed with an end of transfer bar  30  proximate trigger  14 ; and an engagement member  68 , shown as an extension member, integrally formed with cam  38  of trigger  16 , and having a hook on the end thereof, wherein engagement member  68  is capable of engaging receiving member  64  as trigger  16  is de-actuated after discharge. Although engagement assembly  60  is shown having the above-described features, one ordinarily skilled in the art will recognize that many possible configurations and assemblies may be used to couple trigger  16  to transfer bar  30  to perform the function of the above-described means for facilitating the relocation of transfer bar  30  from its extended position to a retracted position. For example, receiving member  64  and engagement member  68  may be formed instead on trigger  16  and transfer bar  30 , respectively, or another configuration may be used instead of a hook and protrusion. An advantageous of the safety mechanism of the present invention is that trigger  16  and transfer bar  30  may each have means for engaging and coupling the other in a releasable relationship and at a proper time in the progression and track of the action assembly. However, for the purposes of explanation and discussion herein, engagement assembly  60  is depicted. 
     FIG. 1 shows engagement member  68  and receiving member  64  in a coupled relationship as the action of the firearm is in a hammer down, safe position. However, as the action, and particularly hammer  14 , moves intermittently from the hammer down position to a half-cocked, loading position and further through to a fully cocked and ready to fire position, engagement assembly  60 , and particularly receiving member  64  and engagement member  68  release from one another, while still maintaining an engageable tracking alignment with one another through the various stages of progression and actuation and de-actuation of the action and trigger. This specific movement and tracking of engagement assembly  60  will be discussed in greater detail below. 
     It should be noted that the means for facilitating the relocation of transfer bar  30  may include other assembly configurations other than those specifically described herein. The specific configuration of the means for facilitating is not intended to limit its function. One ordinarily skilled in the art will recognize the several other potential configurations and/or assemblies that may be implemented and utilized to releasably couple trigger  16 , or one of its connected components, to transfer bar  30  for the specific purpose of assisting transfer bar  30  to retract from its extended position. 
     FIG. 2 illustrates the firearm action of FIG. 1, wherein the action is in a half-cock, loading position. In the half-cock position, the hammer  14  has been rotated away from receiver  24  to a point where a trigger sear  44  engages a sear half-cock notch  46  in hammer  14 . When trigger sear  44  is engaged in sear half-cock notch  46 , the trigger may not be actuated and the hammer is prevented from any forward movement. Movement of hammer  14  rotationally clockwise (FIG. 2) achieves engagement of trigger sear  44  in sear half-cock notch  46  resulting in the action being in the half-cock position. Rotation of hammer  14  also rotates plunger  52 , which is partially recessed into hammer  14 . The position of plunger  52  under cylinder lock  20  results in the lifting of an end  54  of cylinder lock  20  when hammer  14  is rotated. The lifting of end  54  pivots lug  34  out of notch  36  to allow cylinder  32  to freely rotate. It is in this position that the embodiment illustrated in FIG. 2 is easiest to load. 
     It should be clear that not all embodiments will have a half-cock or loading position on the hammer into which the trigger sear may be engaged. This position is merely utilized to demonstrate the movement of the transfer bar relative to the trigger. In this position, transfer bar  30  is upheld by carrier pin  42  and is not in contact with trigger  16 . As the hammer  14  is rotated rearwardly between the safe position and the half-cock position, transfer bar cam  40  may momentarily contact trigger cam  38 . It is important to note that although such contact may occur in some embodiments, one aspect of the invention is that such contact does not occur in the full-cock position, and that such contact does not occur until after the trigger has been fully actuated. 
     Although plunger  52  is shown elevating end  54  of cylinder lock  20 , it should be appreciated that other structures may be used to elevate end  54  in conjunction with the rotation of hammer  14 . The only structural limitation imposed on the elevator is that it must be able to be recessed into hammer  14  so that upon activation of the trigger, the forward rotation of the hammer will not be impeded. This can be accomplished by spring-loading the plunger so that the plunger will retract into the hammer upon impact against end  54 . Plunger  52  is biasing outwardly out of hammer  14 , but retracts to pass by rearward portion  48  and end  54  after trigger  16  has been actuated and hammer  14  is rotated in a forward direction. Although not illustrated, it is well known in the art that hammer  14  can be biased using several techniques, the most common of which is a spring located within the grip three. Similarly, a biasing means such as a spring  31  is utilized to bias transfer bar  30  in a downward direction. The bias supplied to transfer bar  30  must be sufficient to assist transfer bar  30  into its retracted position before an inadvertent release of hammer  14  allows contact with firing pin  22 . 
     FIG. 2 also illustrates means for coupling transfer bar  30  to trigger  16  or trigger cam  38 , comprising an engagement assembly  60 . In this position engagement assembly  60  is shown in a decoupled relationship. Particularly, receiving member  64  (shown as a protrusion in an end of transfer bar  30 ) is shown separated and released from engagement member  68  (shown as an extension, from trigger cam  38 , having a hook). In function, engagement assembly  60  releases or decouples as hammer  14  is drawn back. It is only intended that engagement assembly be coupled or engaged when hammer  14  and the action of the firearm is in the hammer down, safe position. As hammer  14  is drawn back, engagement assembly  60  disengages. Specifically, as hammer  14  is drawn back, receiving member  64  and engagement member  68  disengage and are released from one another. This separation allows transfer bar  30  to relocate or slide within recess  26  to its extended position enabling the firearm to discharge. 
     Although engagement assembly  60  disengages as hammer  14  is drawn and continues to be disengaged through the entire track of the action of the firearm, and particularly hammer  14 , its alignment is maintained because of the subsequent interaction of transfer bar cam  40  and trigger cam  38  once the action, and particularly hammer  14 , is moved out of its hammer down, safe position. Thus, as discharge occurs and hammer  14  is thrust to its hammer down, safe position, both receiving member  64  and engagement member  68  remain and are properly aligned, wherein receiving member  64  is ready to receive engagement member  68  upon release of trigger  16 . 
     FIG. 3 depicts the action illustrated in FIGS. 1 and 2 in the “full-cock” or “ready-to-fire” position. In this position, cam  38  of trigger  16  is not in contact with transfer bar  30 . Transfer bar  30  is in its extended position filling recess  26  and is interposed between firing pin  22  and hammer face  28 . Transfer bar  30  is raised to and held in the extended position by the means for positioning. In this embodiment, the means for positioning is carrier pin  42 , which is attached to hand  18 . Rotation of the hammer to the full-cock position results in the movement of hand  18  and concomitant upward movement of carrier pin  42  and transfer bar  30  to the extended position. Inadvertent release of hammer  14  at this point would result in transfer bar  30  being biased out of the extended position at a point in the travel of hammer  14  between the full-cock and the hammer down positions. In other words, no discharge would occur. Instead, hand  18 , which is attached to hammer  14  would be lowered, thereby lowering carrier pin  42 . The lowering of carrier pin  42  into its retracted position would subsequently allow transfer bar  30  to drop as biasing means or spring  31  exerts a downward force upon transfer bar  30 , thereby causing transfer bar  30  to retract and opening the portion of recess  26  allowing contact of hammer  14  with the rear of receiver  24  without transferring kinetic energy to firing pin  22 . 
     During intentional firing of the firearm, however, full actuation of trigger  16  results in the pivoting of cam  38  into contact with transfer bar cam  40  and continued pressure on trigger  16  retains transfer bar  30  in the extended position despite the lowering of hand  18  and carrier pin  42 . By maintaining transfer bar  30  in the extended position, the kinetic energy created by the release of hammer  14  is transferred through transfer bar  30  into firing pin  22  thereby discharging the cartridge. 
     The advantage to this aspect of the invention is that trigger  16  may be actuated without the weight of transfer bar  30  being placed on cam  38 . The weight of transfer bar  30  is not borne by cam  38  until after trigger  16  has actuated the release of hammer  14 . This results in a much lighter and smoother pull and thereby imparts more accuracy to the firearm. 
     Plunger  52  may be seen in phantom at a position above end  54 . Rotation of hammer  14  to the full-cock position concomitantly rotates plunger  52  around end  54 , thereby releasing end  54  and allowing lug  34  to be biased back into notch  36 . 
     Engagement assembly  60  is illustrated in its fully disengaged position, wherein receiving member  64  and engagement member  68  are separated, yet still aligned for subsequent engagement. The relationship of engagement assembly  60  in this position is similar to the one described and shown in FIG. 2, but with further separation of receiving member  64  and engagement member  68 . 
     FIG. 4 depicts the action in FIGS. 1 through 3 after the trigger has been fully actuated, but before the trigger has been released. As previously discussed, if trigger  16  is released before hammer  14  and transfer bar  30  contact firing pin  22 , then transfer bar  30  will be biased into the retracted position and recess  26  will be exposed into which firing pin  22  will enter. Since recess  26  is dimensioned larger than the portion of firing pin  22 , which extends beyond receiver  24 , no contact is made between hammer  14  and firing pin  22  when transfer bar  30  is in a retracted position. When trigger  16  is maintained in the actuated position, however, cam  38  maintains transfer bar  30  in the extended position and the kinetic energy from hammer  14  is transferred through transfer bar  30  into firing pin  22  and the cartridge within the chamber is discharged. 
     Upon release of the trigger, transfer bar  30  will be biased and assisted downward to once again rest on the means for positioning. Firing pin  22  will be biased outward into recess  26  and the action will be ready to be cycled once again. 
     FIG. 4 also illustrates the relative position of engagement assembly  60  upon actuation of trigger  16 , but before trigger  16  is released. In this position, hammer  14  is in its hammer down, safe position, thus properly aligning receiving member  64  with engagement member  68 . However, as trigger  16  is not yet released, engagement member  68  is merely positioned ready to engage receiving member  64 . As shown, engagement member  68  is elevated above receiving member  64  due to the backward position of trigger  16 . To properly facilitate the relocation of transfer bar  30  from its extended position to its retracted position, trigger  16  must be released, thus making engagement assembly  60  dependent upon trigger  16 . As trigger  16  begins its release, engagement member  68  is brought into contact with and engages receiving member  64 . As trigger  16  continues to be released progressing towards its resting position, engagement assembly  60 , and particularly the coupling of engagement member  68  and receiving member  64 , facilitates the sliding of transfer bar  30  along recess  26  into its retracted position. 
     Engagement assembly  60  merely facilitates the relocation of transfer bar  30  as transfer bar  30  also has biasing means  31  coupled thereto that is capable of biasing transfer bar  30  and assisting it into its retracted position. Engagement member  60  and biasing means  31  function together to retract transfer bar  30 . 
     The engagement assembly of the present invention is advantageous in that it enables the safety mechanism of the present invention to operate in a smooth and efficient manner, as well as preventing transfer bar  30  from being intermittently trapped between firing pin  22  and hammer  14  upon discharge of the firearm and release of hammer  14  from its fully cocked position to its fully down, safe position. In addition, by utilizing an engagement assembly biasing means  31  is not required to be the sole means responsible for retracting transfer bar  30  upon discharge of the firearm. This allows biasing means  31  to be manufactured with a smaller spring tension, which helps to reduce the kick potential of trigger  16  that is experienced when trigger cam  38  and transfer bar cam  40  come in contact with one another. Reducing the kick in trigger  16  helps decrease the chance that trigger  16  will catch the half-cock position if used on a firearm equipped with such a position. 
     The present invention may be embodied in other specific forms without departing from its spirit of essential characteristics. The described embodiments are to be considered in all respects only al illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims, rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope