of polyethylene, and capable of serving as a pellet magazine.
When a magazine bottle of pellets is affixed to upstanding tubular member 32, the pellets feed by gravity into and fill conduits 30 and 31 with a single line of pellets, as shown in dotted lines in FIGURE 4. And, when plunger 18 is in retracted position, one pellet will have passed down out of conduit 30 into conduit 26 and be ready for ejection, as shown, for example, in FIGURE 7.
In case the operator wishes to determine by visual inspection that a pellet is in place and ready for ejection, a sight hole 33 is provided in generally hemispherical cavity 34. This sight hole is positioned to permit view of a pellet located at the intersection of conduits 30 and 26. The dimensioning of sight hole 33 and cavity 34 are not critical, though it is evident that hole 33 should be small enough so that there will be no sideways displacement of a: pellet thereinto, while large enough to allow a clear view of a pellet in place. Cavity 34, by reducing the thickness of the metal in which sight hole 33 is located, makes it easier to see through sight hole 33 into the chamber of the implanter. For a pellet implanter sized to handle the common 15 mg. pellets of diethylstilbestrol, a sight hole of %e inch diameter has proven satisfactory.
Opposite sight hole 33 (in sinistral half-shell 13) is a horizontal slit 35 in dextral half-shell 14, extending from the side of conduit 26 to a cylindrical cavity 36 in the outer face of dextral half-shell 14. Aligned with slit 35 is a narrower slit 37 in a cap member 38 removably affixed to dextral half-shell 14 by machine screws 39.
A yoke safety catch 40 (which may conveniently be stamped out of sheet metal), of which FIGURE 9 shows an enlarged view, is formed with a rearwardly extending shank 41 sized to fit slidably in the slit 37 in cap 38, and with shoulder portions enough water than shank 41 to prevent yoke 40 from passing through slit 37, but permitting yoke 40 to fit slidably in slit 35. Yoke 40 is furthermore formed with two forwardly extending corners 43 and 45 between which is an inwardly extending curvature as best seen in FIGURE 9. This curvature between points 43 and 45 may be composed of three straight-line segments, as shown, or may be a smooth curve. It is important that point 45 extend somewhat further forward than point 43, as is indicated by the dotted base line in FIGURE 9. Preferably edges 46 and 47 of yoke safety catch 40 intersect at (or near) point 43 at an angle of from about 45 to 60 degrees. The corners of yoke safety catch 40 are preferably rounded to a very small radius, such as Yei" or less, as this results in somewhat smoother operation of the device.
As the pellet implanter is assembled, the yoke safety catch 40 rests in the slits 35 and 37, with a coil spring 48 under compression between shoulders 42 of yoke safety catch 40 and the inner face of cap 38 tending to urge points 43 and 45 of catch 40 inwardly and into pellet conduit 26. It will be seen from FIGURES 6, 7, and 8 that the deepest portion 44 of the concavity between points 43 and 45 is aligned with vertical pellet conduit 30.
Point 43 of safety catch 40 is adapted to serve as a click, and rests against the cylindrical surface of plunger 18 very near the forward end of said plunger when said plunger is in the retracted position, as can be seen in FIGURES 3 and 6. As will also be seen from the figures, the forward end of plunger 18 reaches just to, but not into, the intersection of conduits 26 and 30 when said plunger is in the retracted position.
As can be seen from FIGURES 6, 7, and 8, a notch 49 with a steep and essentially perpendicular wall 65 at its rear is formed in the dextral side of plunger 18 near its forward end; the sloping wall of this notch terminates at the exterior cylindrical surface of the plunger at a point just to the rear of the portion against which click point 43 of safety catch 40 rests when the plunger is in retracted position. Since safety catch 40 is continuously urged against plunger 18 by compressed coil spring 48, it will
be seen that unless safety catch 40 is prevented somehow from engaging within notch 49, plunger 18 cannot be advanced. This is shown in FIGURE 6 which shows plunger and safety catch in solid lines in their position when the
5 plunger is fully retracted, and in dotted lines in their locked position. However, if a generally spherically hormone pellet 50 is in place at the intersection of conduits 26 and 30, as shown in FIGURE 7, then as plunger 18 is advanced, it pushes pellet 50 ahead of it, causing the
10 pellet to cam safety catch 40 back into slits 35 and 37 so that click point 43 does not engage notch 49; under these circumstances, plunger 18 may be advanced freely to push pellet 50 completely through needle 27. As is evident from the drawings, the half-shells of body portion 11
lg are provided with studs 51 in dextral half-shell 14 and matching recesses (not shown) in sinistral half-shell 13 to maintain proper positioning of the parts, and are held together by machine screws 52 threaded into screwholes 53.
2o While a container of hormone pellets is attached in inverted position to plastic tube 32, it will be evident that the pellets will pass by gravity into tube 32 and thence through conduit 30 to its intersection with conduit 26, and each time the trigger 15 is squeezed into grip 12, the
2g plunger 18 will advance, pushing a pellet ahead of it which cams safety catch 40 away from plunger 18 so that the plunger is free to move through conduit 26 and needle 27 ejecting the pellet. When the last pellet has been expelled, safety catch 40 engages and locks in the notch
30 49 of plunger 18 after it has been advanced slightly, locking plunger 18 against further motion, and alerting the operator to the fact that a new supply of hormone pellets needs to be attached to the implanter.
The pellet implanter of this invention is extremely con
35 venient for use in implanting hormone pellets into the necks of poultry or into the ears of cattle or other large meat animals. The operator can be certain that one pellet will be implanted each time the trigger is squeezed, and is notified of the exhaustion of the pellet supply by its
40 being impossible then to squeeze the trigger. Also, by means of the sight-hole 33, it is possible to determine by visual inspection whether or not a pellet is in position for implanting.
Although the foregoing invention has been described
d5 in some detail by way of illustration and example for purposes of clarity of understanding, it is to be understood that certain changes and modifications may be practised within the spirit of the invention and the scope of the appended claims.
50 What is claimed is:
1. A pellet implanter comprising, in combination, a body member, a hollow injection needle mounted on said body member and extending forwardly therefrom, a pellet-conveying conduit in alignment with said hollow
55 needle and extending rearwardly therefrom into said body member, a second pellet-conveying conduit within said body intersecting said first pellet-conveying conduit and extending at an angle thereto, means for introducing pellets into said second conduit from a pellet magazine,
g0 a plunger maintained in alignment with said needle and said first pellet-conveying conduit, said plunger being adapted for reciprocating motion through said first conduit and said needle whereby to eject pellets therethrough, the forward end of said plunger being contained within
65 said first conduit when in its retracted position and reaching to the proximal side of said intersecting second conduit, hand-operable means for moving said plunger forward to advance a pellet completely through said needle, catch means retractably spring-urged into said first con
70 duit and a capable, when in its spring-advanced position, of defining within said conduit a pellet-receiving space immediately forward of the distal end of said plunger when in its retracted position capable of containing a single pellet, said catch means being adapted, when in its
75 advanced position, to obstruct advance of said pellet into