Abstract:
The hammer of a gun has a channel in its front face, making direct contact between the hammer and the gun&#39;s firing pin impossible. The tip of a transfer bar retained within the channel moves to fill the channel and thus permit firing of the gun, only when the trigger is pulled. This construction avoids certain types of accidental discharge.

Description:
BACKGROUND OF THE INVENTION 
   This invention relates to guns, particularly rifles having firing pins. 
   Every gun has a mechanism which fires an ammunition round when the trigger is pulled. Most guns have at least one safety to prevent inadvertent discharge of the round. Typically, a spring-loaded hammer is released when the trigger is pulled; the hammer falls either directly against a round, or against a firing pin which in turn strikes the round. Firing pin safeties are sometimes used in the latter type of gun. Trigger safeties are very common in all types. Neither type of safety, however, prevents certain types of inadvertent firing, for example when a loaded gun is dropped. Then the hammer may strike the round or the firing pin, without the trigger having been moved. 
   SUMMARY OF THE INVENTION 
   An object of the invention is to prevent certain types of inadvertent gun discharge. 
   Another object is to provide a safety mechanism which does not interfere with sliding contact between the gun&#39;s bolt and hammer. 
   These and other objects are attained by a mechanism which includes a hammer having a channel in its forward face, the channel providing clearance around the rear of the firing pin so that the hammer cannot directly strike the firing pin. A transfer bar is mounted in the channel, and the tip of this element moves to a position filling the channel behind the firing pin, so as to impact the firing pin, only when the trigger has been pulled. Thus inadvertent firing, when the trigger has not been pulled, is prevented. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings depict, by way of example, a lever action rifle. It should be understood, however, that the invention is not limited to this type of gun, and in fact may be applied to any gun having a hammer, a trigger and a firing pin. 
       FIG. 1  is a sectional side elevation of a portion of a lever action rifle embodying the invention; 
       FIGS. 2–6  are the same view of the gun, at an enlarged scale, with many parts removed for clarity, showing a normal firing sequence; 
       FIG. 7  is an isometric view of selected parts of the gun; and 
       FIG. 8  is another isometric, with the hammer removed to show underlying detail. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The lever action rifle shown in  FIG. 1  is largely conventional, in that it includes a stationary receiver  10  to which a stock (not shown) is attached at the rear, and a barrel  12  is attached at the front. The receiver has a cavity  14  in which a bolt  16  can slide fore and aft. The bolt is moved by the forward end  18  of the finger lever  20  which pivots on a transverse pin  22  extending through holes at the bottom of a trigger guide plate  23 . The guide plate is attached, front and rear, to the bottom of the receiver by screws (not shown). 
   The rifle illustrated has a two-piece firing pin assembly, lying on an axis aligned with that of the barrel. The front firing pin part  24  has a nose  26  which impacts the detonator of an ammunition round when it is driven forward by the rear part  28  of the firing pin. The rear part has a front surface with a bevel  30  ( FIG. 2 ) at the top; the front part has a rear surface with a complementary bevel  32  at the bottom. When the parts are axially aligned, as shown in  FIG. 1 , the rear part can drive the front part forward; however, when the gun is being cocked, the rear part can pivot downward, and in this configuration the firing pin is discontinuous and will not operate to fire the round. This provides safety in case the gun is dropped, or the hammer is manually released, when the gun is not cocked. A locking bar  34  moves upward when the lever is in the closed position shown in  FIG. 1 ; the bar pushes the rear part  28  of the firing pin upward into alignment with the front part  24 , enabling firing. 
   While the described example has a two-piece firing pin, it should be understood this invention is also applicable to guns having a one-piece firing pin. 
   The hammer  36  of the gun is mounted on a pivot pin  38  ( FIG. 2 ). The hammer is urged forward by a spring  40  ( FIG. 1 ) mounted around a guide rod  42 , which passes through a hole in a guide  44  attached to the receiver. The hammer can be drawn rearward with the thumb, or pushed back by the bolt  16  when the lever  20  is operated, to a cocked position. 
   A sear is a latch which holds the hammer in its cocked position. In this example, the sear  46  is biased forward to its latched position ( FIG. 3 ) by a spring, and it is moved rearward to its unlatched position ( FIG. 4 ) when the trigger is pulled rearward. 
   A trigger lock prevents the trigger from being pulled until the trigger lock is released. The trigger lock in this example is a lever  50  mounted on a pin  52  supported in the trigger guard plate. It has a front portion  54  which can protrude downward through a slot in the guard plate to a position behind the trigger  56 . This blocks trigger movement. The trigger lock is urged toward its locking position by a small coil spring (not shown) pressing upward on it at the rear. This bias is overcome by contact with an upper surface  60  on the finger lever when the finger lever is moved to its ready-to-fire position. The lever is latched in this ready position by a flexible pin (not shown) which engages below a protuberance on the finger lever. 
   To this point, the illustrated gun is conventional. The new features of this invention are described below. 
   As shown in  FIGS. 2 and 7 , the bottom end  62  of the hammer  36  sits in a cradle or rocker  64  which is mounted on the same pivot pin  38  as the hammer and thus has the same pivot axis. There is a lost-motion connection between the hammer and the rocker: when the hammer is drawn rearward, it engages the rocker during only about the rear half of its travel, pivoting the rocker in the same direction. But when the hammer is forward, the rocker can be pivoted rearward with respect to the hammer by holding the trigger back. A compression spring  66  ( FIG. 8 ) seated on a pad  69  extending laterally from the sear and bearing upward against the rear  68  of the rocker resists this rearward pivoting, ensuring that the rocker is always tilted forward to the extent possible as the hammer falls. 
   The front end of the rocker has aligned transverse holes in its parallel sides  70 . An upwardly extending boss  72 , also with a transverse hole in it, is provided on the top surface of the trigger. A U-shaped rigid link  74  is installed with one transverse arm  76  in the rocker holes, and the other transverse arm  78  in the trigger boss hole, so that movement of the trigger and the rocker are related: they must pivot in opposite directions. Other linkages or mechanisms for producing this related movement may be possible. 
   The forward link arm  76  extends not only through the holes in the rocker, but also through a hole  80  at the bottom of a transfer bar  82  whose bottom portion is confined between the sides  70  of the rocker. The transfer bar is designed to avoid interfering with the sliding bolt movement. The bar has a straight upper tip portion  84  received in a channel  86  formed in the front surface of the hammer. A spring pin  88  passing through ears  90  in the hammer on either side of the channel retains the transfer bar in the channel. The channel is wider than the diameter of the rear end of the firing pin assembly, and is deep enough to clear it. The firing pin does not touch the sides, or the bottom, of the channel, even when the hammer is in its fully forward position. In fact, the hammer never directly contacts the firing pin; the two parts make contact only indirectly, through the transfer bar. Unless the tip of the transfer bar is in high in the channel, in a position behind the firing pin, the firing pin will not be struck, regardless of the motion or position of the hammer. This is true whether the hammer falls accidentally or is slowly let down with the thumb. 
   The tip  84  of the transfer bar is normally in a safe position in the channel, below the level of the firing pin. The position of the tip is determined by the angular position of the rocker relative to the hammer, and this relative position is controlled by the trigger; thus, the transfer bar is in a position to contact the firing pin only when the trigger is pulled. 
   The movement of the transfer bar is depicted in the sequence of  FIGS. 2–6 . As mentioned above, the sear  46  is in its latched position in  FIG. 3 . It has been moved rearward to its unlatched position ( FIG. 4 ) by pulling the trigger, which rotates the sear counter-clockwise.  FIG. 5  shows the hammer starting to fall toward the firing pin. In  FIGS. 2–6 , the angle α between the rocker and the hammer is increasing. One can see from those figures that this relative rotation drives the transfer bar upward in its channel. The only time the tip of the bar is high enough in the channel to strike the firing pin is when the trigger is rearward and the hammer is forward ( FIG. 6 ).  FIG. 1  shows what happens when the hammer is released, without pulling the trigger. The tip portion  84  of the transfer bar  82  is below the level of the firing pin, and the hammer does not strike the pin. 
   The transfer bar need not be shaped exactly like the one shown in the drawings. It is possible, for example, to make the channel and the upper portion of the transfer bar curved, or to change the degree of offset between the upper portion and the lower portion. The principles of the invention may even be applied to guns not having firing pins. One might, for example, form a protuberance on the transfer bar tip intended to strike the ammunition detonator only when the bar was raised. Or one might modify the channel, for example by removing one of its sides, without substantially affecting its function. The claims below are intended to cover all such variations. 
   Since the invention is subject to modifications, it is intended that the foregoing description and the accompanying drawings shall be interpreted as only illustrative of the invention defined by the following claims.