Spring air gun with pivoting barrel
BACKGROUND AND SUMMARY 
     This invention relates to a spring air gun with a pivoting barrel. More particularly, the invention relates to such a gun with an improved fork member for pivotably mounting the barrel and for retaining the barrel in a firing position and a safety mechanism for preventing the gun to be fired when the barrel is not in the firing position. 
     A spring air gun generally includes a barrel for holding a projectile, a compression tube, and a spring-biased piston reciprocably mounted in the compression tube. The gun is cocked for firing by moving the piston to compress the spring. When the gun is fired, the spring drives the piston to compress the air within the compression tube, which propels the projectile from the barrel. 
     Spring air guns commonly include a pivoting barrel which is connected to a cocking lever for cocking the piston when the barrel is pivoted away from its firing position. As described in U.S. Pat. No. 5,205,271, the barrel is advantageously pivotably mounted in a fork member which is inserted into the compression tube. 
     The invention provides an improvement over the gun which is described in the patent. A single dowel pin attaches the fork member to the compression tube. The compression tube is also forked, and the fork of the compression tube engages and reinforces the outside of the fork member. The barrel is pivotally connected to both of the forks by a single dowel pin. A spring clip on the barrel releasably engages a stud on the fork member to retain the barrel in the firing position. The butt stock of the gun is attached to the fork member by screws which threadedly engage internally threaded inserts in the fork member. A trigger blocking mechanism engages the cocking lever when the barrel is not in the firing position and prevents the trigger from being pulled. 
    
    
     DESCRIPTION OF THE DRAWING 
     The invention will be explained in conjunction with an illustrative embodiment shown in the accompanying drawing, in which 
     FIG. 1 is a side elevational view, partially broken away, of a gun formed in accordance with the invention; 
     FIG. 2 is a top view, partially broken away, of the compression tube; 
     FIG. 3 is a side elevational view, partially broken away, of the compression tube; 
     FIG. 4 is a sectional view taken along the line 4--4 of FIG. 3; 
     FIG. 5 is a right end view of the compression tube; 
     FIG. 6 is a bottom view of the compression tube; 
     FIG. 7 is a top view of the fork member; 
     FIG. 8 is a side view of the fork member; 
     FIG. 9 is a sectional view taken along the line 9--9 of FIG. 8; 
     FIG. 10 is a right end view of the fork member; 
     FIG. 11 is a sectional view taken along the line 11--11 of FIG. 10; 
     FIG. 12 is a bottom view of the fork member; 
     FIG. 13 is a sectional view of the barrel assembly; 
     FIG. 14 is a top view of the barrel assembly; 
     FIG. 15 is a side view of the barrel assembly taken along the line 15--15 of FIG. 14; 
     FIG. 16 is a bottom view of the barrel assembly; 
     FIG. 17 is a left end view of the barrel assembly; 
     FIG. 18 is right end view of the barrel assembly; 
     FIG. 19 is an enlarged sectional view of the barrel insert; 
     FIG. 20 is an enlarged fragmentary sectional view of the breech end of the barrel insert; 
     FIG. 21 is a sectional view of the detent clip for the barrel assembly; 
     FIG. 22 is a top view of the detent clip; 
     FIG. 23 is a right end view of the detent clip; 
     FIG. 24 is a top view of the cocking lever; 
     FIG. 25 is a side view of the cocking lever; 
     FIG. 26 is a right end view of the cocking lever; 
     FIG. 27 is a top view of the trigger; 
     FIG. 28 is a side view of the trigger; 
     FIG. 29 is a bottom view of the trigger; 
     FIG. 30 is a right end view of the trigger; 
     FIG. 31 is a fragmentary left side view of the trigger; 
     FIG. 32 is a sectional view taken along the line 32--32 of FIG. 31; 
     FIG. 33 is a top view of the stock; 
     FIG. 34 is a side view of the stock; 
     FIG. 35 is a bottom view of the stock; 
     FIG. 36 is a sectional view of the stock; 
     FIG. 37 is a right side view of the left hand receiver; 
     FIG. 38 is a left side view of the right hand receiver; 
     FIG. 39 is a sectional view taken along the line 39--39 of FIG. 37; and 
     FIG. 40 is a sectional view taken along the line 40--40 of FIG. 38. 
    
    
     DESCRIPTION OF SPECIFIC EMBODIMENT 
     Referring first to FIGS. 1 and 33-40, a gun 20 includes a frame comprising a stock 21 and a receiver formed from right and left hand receivers 22 and 23. The right and left hand receivers are bolted together in the conventional manner, and the left hand receiver is secured to the stock by screws 24 and 25. 
     A compression tube 31 is mounted on the receiver, and a piston 32 is reciprocable within the compression tube. The piston includes a piston rod 33 and a radially enlarged piston head 34. A compression spring 35 engages the piston head and resiliently biases the piston to the right. The left end of the compression spring engages a washer 36 which is anchored within the rear end of the compression tube. 
     A fork member 38 is secured within the forward end of the compression tube and will be described more fully hereinafter. 
     A barrel assembly 40 is pivotably mounted on the fork member and is pivotable between a firing position which is illustrated in FIG. 1 and a cocking position. 
     A cocking lever 42 is slidably supported by the stock 21 and is connected to the barrel by a link 43. The link is pivotably connected to the lever and the barrel by pins 44 and 45. 
     Referring to FIGS. 24-26, the cocking lever 42 is generally channel-shaped and includes a bottom wall 46 and a pair of side walls 47. The rear ends of the side wall include upwardly extending pusher arms 48. 
     The gun is cocked by pivoting the barrel clockwise from the firing position of FIG. 1. The cocking lever moves rearwardly, i.e. toward the person cocking the weapon or to the left (in FIG. 1), and the pusher arms 48 engage an annular flange 49 on the piston rod 33 and slide the piston rearwardly against the force of compression spring 35. The piston is latched in the cocked position shown in FIG. 1 by a sear 50 which engages an annular shoulder 51 on the piston rod. The cocking lever is slidably supported by ribs 26 on the stock 21. 
     The shoulder 51 is in front of a flared camming surface 52 which engages the sear and rotates the sear counterclockwise into the latching position as the piston moves rearwardly. A sear spring 53 biases the sear to rotate clockwise, and the sear is retained in the latching position by a cam 54 on trigger 55. 
     The gun is fired by pulling the trigger, which rotates the cam 54 clockwise out of engagement with the sear 50. The sear spring rotates the sear out of engagement with the shoulder 51, and the compression spring 35 forces the piston forwardly at high speed. The rapidly moving piston compresses the air in the compression tube and forces the compressed air through an opening in the fork member 38. A projectile within the barrel is propelled out of the barrel by high velocity air which flows through the opening in the fork member. 
     Referring to FIGS. 2-6, the compression tube 31 includes a cylindrical central portion 58, a forked front portion 59, and a rear portion 60 which is provided with a recess 61 in the bottom. The forked front portion includes a pair of arms 63. Each of the arms has an arcuate cross section and a concave inside surface 64. An opening 65 is provided through each of the arms, and openings 66 are provided at the junction of the arms and the cylindrical portion 58. 
     The compression tube is advantageously formed from carbon steel tubing. 
     Referring now to FIGS. 7-12, the fork member 38 includes a cylindrical body or plug 68 and a pair of arms 69. The cylindrical body is sized to fit snugly within the front end of the cylindrical portion of the compression tube. An O-ring fits into an annular groove 70 in the body and provides an airtight seal between the body and the compression tube. The fork member is secured to the compression tube by a single dowel pin 71 (FIG. 1) which extends through an opening 72 in the body of the fork member and the openings 66 in the compression tube. A stop shoulder 73 on top of the body engages the front edge of the cylindrical portion of the compression tube. 
     An orifice 74 is provided in the body of the fork member to allow compressed air to flow out of the compression tube. Each end of the orifice is flared. 
     Each of the arms 69 of the fork member includes an arcuate or convex outer surface 75 (FIG. 10) which mates with and engages a concave inner surface 64 of one of the arms 63 of the compression tube. The metal arms 63 reinforce the arms of the fork member and provide a stiffer and more secure mounting for the barrel than previous fork members. 
     The barrel assembly 40 is pivotably mounted between the arms 69 of the fork member by a dowel pin 76 (FIG. 1) which extends through openings 77 in the arms 69 and the openings 65 in the arms 63. 
     A lug 79 extends downwardly from each of the arms 69. An internally threaded insert or bushing 80 (FIG. 11) is inserted into an opening 81 in the lug and is ultrasonically welded in place. The stock 28 is secured to the inserts by screws 82 (FIG. 1). 
     A generally cylindrical stud 84 extends forwardly from the body of the fork member between the arms 69. As will be explained hereinafter, the stud maintains the barrel in the firing position. 
     The fork member is advantageously molded integrally from glass filled nylon plastic. 
     The barrel 40 includes a molded plastic barrel housing 86 (FIGS. 1 and 15-18) and a steel tubular barrel insert 87 which is insert molded within the housing. The barrel housing includes an elongated tubular central portion 88, a front end portion 89 which includes a sight 90, and a rear end portion 91 which includes a pair of spaced-apart mounting flanges 92. The mounting block is provided with openings 93 for the dowel pin 76 which pivotably mounts the barrel assembly within the fork member and openings 94 for the pin 45 which attaches the link 43. The dowel pin 76 which pivotally mounts the barrel assembly extends through an annular groove 96 (FIG. 19) in the barrel insert and through a concave groove 97 (FIG. 13) in the bore of the barrel housing. 
     The rear end or breech end 98 of the barrel insert extends beyond the barrel housing, and a detent clip 99 (FIGS. 21-23) is mounted on the exposed end of the barrel insert. The detent clip includes a cylindrical collar 100 which fits snugly over the breech end of the barrel and a pair of curved arms or clips 101 which are separated by an open mouth 102. 
     The detent clip is molded integrally from plastic such as Delrin. The molded plastic arms 101 are flexible and resilient and provide a spring retaining clip for maintaining the barrel in the firing position in which the bore of the metal barrel insert 87 is aligned with the orifice 74 of the fork member. 
     The open mouth 101 of the detent clip is narrower than the diameter of the stud 84 of the fork member. As the barrel is rotated counterclockwise toward the firing position, the arms of the detent clip are cammed open by the cylindrical stud and then snap back around the stud to retain the barrel in the firing position. The curvature of the arms 101 is substantially the same as the curvature of the stud, and the spring clip holds the barrel in alignment with the orifice 74 of the fork member. Referring to FIG. 20, the breech end of the barrel insert includes an outwardly flared or frusto-conical extension 103 which retains an O-ring for sealing against the fork member. When the barrel is rotated clockwise to move the cocking lever 42, the arms of the spring clip spread apart and pass over the stud 84. 
     Referring to FIGS. 27-32, the trigger 55 includes a curved finger portion 105 and a pivot opening 106 for a pin which pivotally mounts the trigger in the receiver. A trigger spring 107 and the cam 54 (FIG. 1) are also mounted on the trigger pin. A safety extension 108 extends forwardly from the finger portion for engaging a safety lock 109 (FIG. 1) which prevents rotation of the trigger when the safety lock is on. 
     A trigger extension rod 111 extends forwardly beyond the finger portion toward the cocking lever 42, (FIG. 1). The extension rod terminates in an upwardly angled end 112. 
     When the barrel is in the firing position of FIG. 1, the rear end of the cocking lever 42 is spaced forwardly of the end of the trigger extension rod 111, and the trigger and extension rod can rotate clockwise to fire the gun. However, if the barrel is not in the firing position, the cocking lever will be moved to the left of its FIG. 1 position and will be engageable with the trigger extension rod to prevent the trigger from being pulled. 
     The gun which is described herein has fewer components than comparable prior art guns and is therefore cheaper and easier to assemble. Fewer components also means improved reliability. 
     While in the foregoing specification a detailed description of specific embodiments of the invention was set forth for the purpose of illustration, it will be understood that many of the details herein given can be varied considerably by those skilled in the art without departing from the spirit and scope of the invention.