Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to humane traps for animals.
For the purposes of this specification a humane trap may
be defined as a trap which despatches a trapped animal without
pain or panic. In practice this means that the trap when sprung
by an animal entering it should reliably and substantially
instantaneously kill the animal, or at the lea~t render it
immediately unconscious with death rapidly supervening. In a
practical trap, there are the further requirements that it be
effective as a trap and that, where fur bearing animals are
trapped, the fur or pelt is not damaged.
Various types of humane trap have been developed, none of
which has been wholly satisfactory. In particular, it has been
di~icult to ensure that the trap when sprung can be relied upon
to strike the animal at such a location and with such force as
to meet the definition of a humane trap set out above.
The object of the invention is to provide a trap which is
of robust and compact construction, and is capable of meeting
the requirements of a humane trap.
My invention provides a trap for animals which comprises
a peripheral frame defining an opening, and having a gap therein,
portions of the frame to either side of the gap being spring
urged towards one another. A pair of strike arms, used to deliver
a killing blow to an animal entering the trap, is pivotally
connected to the frame, one arm to each side of the gap, and the
arms are pivotally connected to one another to form a toggle
linkage which the spring loading of the frame urges into a more
or less collapsed condition within the frame opening when the
trap is in a sprung condition. A latch is provided to hold the
assembly of frame and strike arms in an alternative set condition
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with the toggle linkage at least partially straightened and the
frame portions to either side of the gap drawn apart. A trigger
device operated by an animal reaching a predetermined position
with its neck in the opening is provided to release the latch,
whereupon the spring urging of the frame portions causes the
toggle linkage to collapse and the strike arms are forced into
the frame opening to deliver a killing blow to the neck of the
animal.
Preferably, the strike arms overlap in scissors fashion
so as to exert a continued clamping action on the animal's neck
after the initial blow. This effect may be augmented by providing
an anvil on that side of the frame opposite the gap which co-
operates with the strike arms, and ensures that in the event of
the initial blow to the neck not proving immediately fatal, the
clamping force will rapidly terminate life without the animal
regaining consciousness.
The latching means may be provided by a wire loop pivotally
connected to the frame for movement between a position in which
it blocks movement of the strike arms out of their set position,
and an alternative position in which it does not block such
movement, the wire loop being configured with a trigger portion,
lyin~ in the path of an animal passing through the opening in
the frame so that such passage results in movement of the loop
into its alternative position. The configuration of the loop is
readily adjusted so that triggering occurs when an animal to be
trapped has reached a position in which a vital part lies in the
plane of the strike armsO
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The principles of the invention may also be employed with
advantage in ~raps incorporating addi~ional features not forming
part of the present invention and still further improving its
performance as a humane trap,
Illu~trative embodiments of the invention are described
with reference to the accompanying drawings, in which:
Figure 1 is a perspective view of one form of trap in
accordance with the invention, in a sprung condition,
Figure 2 is a front elevation of the same trap, in a set
condition,
Figure 3 is a front elevation of a further embodiment of
the trap, in a set condition, and
Figure 4 is a front elevation of a portion of the trap
of Figure 3, in a sprung condition.
Referring first to Figures 1 and 2, a trap comprises a
peripheral frame member fabricated from spring steel ~trip and
bounding three sides of a quadrilateral opening 130 In oxder
to allow the trap to be located in an appropriate position, a
plate lQ is secured to that side of the frame member opposite its
open side, which plate may be staked, pegged, nailed, tied or
otherwise secured in a desired location~ Additionally or alternative-
ly, one or more wire stays 11 may be provided.
The free ends of the frame member 1 are twisted through
90 so as to lie in a common plane, and are secured by pivots 2
to strike arms 3a and 3b, which in turn are connected together
by a pivot 4 so as to form a toggle linkage lying in the plane
of the opening 13. Aq shown in Figure 1, this takes up a more
or less collapsed condition when the trap i5 in its sprung condition,
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b~t when the trap is in the set condition shown in Fi~ure 2,
the linkage is almost s~raighten~. In order to bring the arms
to their set position, it is necessary to spread further apart
the free ends of the frame 1, involving the storage of potential
energy in the spring steel of the frame, and the trap is both
latched in the set condition and triggered by means of a wire
loop 8, the ends of which are pivoted in the sides of the frame~
and a central portion of which extends perpendicular to the plane
of the frame to form a saddle which latches the toggle linkage
against collapse when the trap is in its set condition. A
stop 12 on the arm 3b prevents over centre movement of the linkage
by engaging the arm 3a. The intermediate portions of the loop
are conigured so that movement of an animal through the frame
opening results in its engaging the loop and dislodging the saddle
from beneath the toggle linkage. Once the saddle is dislodged,
the strike arms 3a and 3b are unlatched, and are accelerated into
the frame opening as the toggle linkage collapses and the potential
energy stored in the frame is converted into kinetic energyO The
accelerated strike arms deliver a killing blow to the animal in
the frame opening: the loop is configured so that it will not be
dislodged until the animal has paqsed its head suf~iciently throug~
~he frame opening for the back of its neck to be situated beneath
the strike arms 3a, 3b, thus maximising the effect of the blow
delivered.
The trap described has the advantages of providing a compact
and simple structure which is capable of delivering a very ef~ective
killing blow to a vital part of an animal being trapped. The
toggle action of the strike arms provides a strike action of
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excellent charac~eristics, the arms being accPlerated to deliver
a sharp chop to the back oE the neck at the base of the skull,
a well known ~ital point, followed by a sq~eezing action on the
neck accomplished by interaction of the overlapping portions
of the strike arms in cooperation with an optional anvil member
7 projecting from the bottom side o~ the frame member 2.
The embodiment of the invention shown in Figures 3 and 4
incorporates further developments which were not invented by me,
but which in conjunction with my invention provide a still
further enhanced perEormance.
The trap comprises a spring frame 20 fabricated from
spring steel and comprising a base spriny portion 22 and two free
end arms 24 joined to the base portion by curved spring portions
21. The spring frame normally assumes the configuration shown
in Figure 4, with the tops of the end arms 24 close together, but
the end arms can be pulled apart so that the frame 20 assumes the
configuration shown in Figure 1. The end arms themselves are
formed with out-turned side flanges 26 flanking a central web 28
having a central aperture (not shown). The purpose of this con-
figuration is to provide arms 24 which are strong and rigid, butat the same time have a shape which can move through water with
a minimum of resistance. This property is significant if the
trap is to be used below water, since under these circumstances
much of the energy stored in the spring frame can be dissipated
in the water if the frame is inappropriately shaped.
It should be borne in mind that a primary Eunction of the
frame is to support the trap in a desired position, and for this
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reason the base spring 22 should be provided with means permitting
the trap to be mounted. These mounting means may take any con-
venient form, for example cross bars secured to the base spring,
or nails or pegs passing through apertures in the base spring.
Such mounting means form no part of the invention, and indeed
will often be provided by the user of the trap as and when
required to position the trap.
The upper end~ of the end arms 24 each support a hinge
bracket 30 comprising a clevis 32, a trigger plate 34 and a pivot
pin 36. The pivot pin 36 passes through the portion 28 of the
end arm 26 and i9 secured in position by a split pin 38 passing
through the pivot. In order to assure free movement of the hinge
bracket, nylon washers 40 are placed between th~ split pin and
the end arm, and the end arm and the trigger plate.
Suspended from the clevises 32 by means of hinges in the
form of clevis pins 42 is a trap mecha~ism indicated generally
by the reference numeral 44.
The trap mechanism comprises two strike bars 46, one
connected at each hinge bracket 30 by the associated pin 42, the
strike bars being interconnected at point~ intermediate their ends
by a further pivot pin 48 orming a ~ulcrum for the action of each
~trike bar and the knuckle joint of a toggle linkage formed by
the two bars 46. Also ~uspended from each clevi~ pin 42 is a
curved link 50, the links 50 ~eing connected by a pivot 52 a~
their lower ends to form a stirrup when the trap is in the condition
shown in Figure 3. The links 50 are ~urther provided with shoulders
54 extending towards one another so that with the trap in its set
condition, the links 50 together form a template defining a collar
:
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surrounding a ~aw 56 forming a desirable opening. I~ order to
match the size of this opening to a species of animal to be
trapped, and in order to improve the action of the trap in a
manner describ~d in more detail hereinafter, two further links
60 are pivotally connected to the members 50 by pivots 62 and to
each other by a pivot 64 to provide a further toggle linkage
which foxms a cradle indicated generally by thP reference numeral
65. The jaw 56 as res~ricted by the links 60, is arranged so
that its dimensions when the trap is set, are such as readily
to pass the head of a species of animal to be trapped, but not
to pass the shoulders of that same species of animal. This jaw
56, which is the only opening of ~ubstantial size in the trap,
presents a desirable opening to an animal seeking to reach bait
placed on the opposite side of the trap to the line ~f an animal's
approach.
The toggle linkage formed by the strike bars 46 is in a
substantially straightened condition when the trap iR in the set
condition shown in Figure 3, with only a small angle be~ween lines
extending from pivots 42 through the pivot 48. The trap is latched
in the set condition by means of a trigger bar 66 which is a
part of a trigger mechanism which will be de~cribed in more detail
below. The trigger bar is attached to one end arm 24 by means
of a pivot 68 and engages a trigger pin 70 on the other end arm
24. When the trigger bar 66 i8 unlatched from the trigger pin 70,
the end arms 24 are urged toward each vther through the a~tion of
the base spring 22. This results in collap~e of the toggle linkage
formed by the strike bars 46, resulti~g in strike edges 72 on the
strike bars being forced downwardly across the opening of the jaw
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56 to deliver a heavy blow to any animal who~e neck extends
through the opening. The strike edges 72 are curved so a~ to
continue to act directly downwards acro~s the opening as the strike
bars 46 turn about the pivots 42. Eventually, the strike bars
reach the position shown in Figure 4, in which the free ends of
the strike bars, which are curved, embrace and exert a clamping
action upon the neck of the animal. Movement of the end arms
24 towards one another also results in the members 50 being moved
towards one another, resulting in turn in the collapse of the
toggle linkage formed by the links 60 and defining the cradle 65,
the free ends of the arms 60 enhan~ing the clamping action on the
neck of the animal, and the portions of the links 6n adjacent to
pivots 64 moving upwardly towards the strike edges 72 so as still
urther to increase the e~fect of the latter.
The trigger mechanism for dislodging the trigger bar 66
from the latch pin 70 comprises a trigger follower 74 secured to
the latch bar 66 and resting on the top surface of the ~rigger
plate 34 on the hinge bracket 3~, the trigger plate being in the
form of a cam configured so that turning movement of the hinge
ao bracket 30 out of the plane of the spring frame 20 results in a
lifting movement being imparted to the follower 74 sufficient to
raisQ the trigger bar 66 clear of the trigger pin 70. The form
of the cam provided by the trigger plate 74 can be very simple,
and a square plate with it~ upper corners ~hamfered i8 entirely
satisfactory,
In use, the trap may be brought to the set condition shown
in Figure 3 by using any suitable device to spread apart the
end arms 24 sufficiently to enable a notch 76 on the under edge
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o~ the trigger bar 66 ~o engage ~he trigger pin 70~ ~ormally
the strength of the ~pring frame 20 will preclude this spreading
apart of the end arms being achieved manually, and a suitable
tool will need to be provided such as some form of ~crew or
hydraulic jack. In order to secure the trap in the set position,
a safety pin 78 may be provided which is passed ~hrough apertUres
in the ~trike bars 46 so as to secure them in the relative position
shown in Figure 4. At this s~age, the base spring 22 may be
mounted by suitable mounting means so as to secure the trap in a
desired position with the trap mechanism 44 suspended and hanging
vertically from the hinge brackets 30 and the trigger bar 66 in
engagement with the trigger pin 70. At this stage, the pin 78
may be removed.
The actual location of the trap will depend on the trapper's
know-how, but it should be noted that the trap of the present
invention gives additional flexibility in positioning in that,
when passing from the set to the sprung position, no part of the
trap mechani~m moves outside the space enclosed within the spring
frame 20, which itself contracts in size as the ~rap is sprung.
This is a con~iderable advantage, since it much r~duces ~e li~e-
lihood of nearby vegetation or object~ obstructing the operation
of the trap, and the overall compact size of khe trap allows it
to be used in locations in which many known traps could not be
used, both because of their overall ~ize and because of the
unobstructed space required around them to enable their free
movement from a set to a ~prung condition.
The trap is baited by placing a suitable bait at some point
beyond the jaw 56 on the oppo~ite side of the trap to the expected
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line of approach of an animal to be trapped. Such an animal, in
seeking to reach the bait, will be attracted by the de~irable
opening provided by the jaw 56 and will paSs its head ~hrough the
opening in an attempt to reach the bait. As previously described,
the jaw is sized so that the shoulders of the animal Cannot pass
through the collar ormed by the links 50 and associated parts,
and therefore the animal in attempting to reach the bait will
press with its shoulders against the collar and in doing so will
swing the entire trap mechanism 44 about the pivots 38 on the
hinge brackets 30.
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