Note: Descriptions are shown in the official language in which they were submitted.
~lC617S
This invention relates to humane traps for animals.
For the purposes oE this specification a humane trap is
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 instantaneou-
sly kill the animal, or at the least render it immediately un-
conscious 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~
- In co-pending patent application Mo. 792,533, filed ~lay
2, 1977, in the name of Armand Jacob, there is described a trap
comprising a trap frame defining an opening, the frame having a
gap therein with portions of the frame to either side of the gap
being spring urged toward one another. A pair of strike arms are
pivotally connected to the frame, one on each side of the gap, and
to each other to form a toggle linkage which, with the trap in
a first released condition, is collapsed within the opening.
Latching means can be located so as to secure the assembly of
frame and strike arms in an alternative condition with the toggle
linkage partially straightened and the frame portions to either
side of the gap drawn apart, a trigger device, actuable by an
animal reaching a pre-determined position in the frame opening,
being provided to release the latch.
One of the most different problems in devising a humane
trap is to guide the animal into the trap and trigger the latter
in such a manner that an animal which triggers the trap is
reliably despatched by a blow which strikes the animal at a pre-
determined vital point, by preference the back of the nec~ at
the base of the skull. Whilst the trap referred to above re-
presents an improvement upon most other known traps in this re-
spect, a still further improvement in performance in this re-
- spect is desirable in a truly humane trap. The present
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~lC617~
invention is therefore directed to improvements in means for
guiding an animal into a trap and triggering the latter which are
particularly, although not exclusively, applicable to the type OL
trap to which the patent application referred to above is directed.
In its broadest aspect, the present invention is directed
to a trap for animals comprising a frame with a mechanism mounted
in the frame and movable between set and sprung conditions.- The
mechanism defines in its set condition a collar presenting a
desirable opening to a species of animal to be trapped and .g~.uged
to resist the passage of the shoulders of an animal of that species.
The mechanism further comprises trigger means operatively associat-
ed with the collar to spring the trap mechanism in respo~se to
engagement of an animal's shoulders with the collar, and strike
means operative on springing of the trap to strike across the
plane of the collar opening with a force lethal to the species
f~ of animal to be trapped.
It is found that when a suitable bait is placed beyond ;
a small enclosed aperture of sufficient size readily to-admit
an animal's head, although not necessarily large enough to pass
its shoulders, the animal is attracted to the aperture and will
: pass its head through it and press for~Jard in an attempt to
reach the bait. Such an opening is referred to above and in this
specification as a "desirable opening", and its size will depend
upon the species of animals to be trapped. The response of
animals to such "desirable openings" has been used as the basis
of the trap of the present invention. A desirable opening is
provided by that portion of the trap mechanism configured so as
to define in its set condition a collar which presents the opening
to the animal, and the collar is associated ~.7ith the trigger so
that ~Jhen the collar is pressed upon by the animal. attempting
. to reach the bait the trigger will release some suitable form
of ~rike means ~7hich acts across the plane of the collar
opening with a force predetermlned as lethal to the
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species to ~ trappecl. The atte~pt of the animal to reach the
bait through the desirable opening causes it to lay the back
of its neck at the base of its s}~ull, which will lie approximately
in the plane of the collar, open to the strike means. It is thus
assured that the strike means will deliver a blow to the appro-
priate portion of the animal's anatomy.
Preferably the collar is mounted within the frame for
movement in the direction in which the animal enters the trap and
out of a plane which it occupies when the trap is in its set
condition, into a trigger release position. Thus the animal in
attempting to reach the bait moves the collar and provides the
motion necessary to trigger the strike means. The most ad-
vantageous form of collar movement is obtained when the collar is
suspended for s~inging movement relative to the frame.
In a preferred form of the trap, the trap mechanism is
suspended for swinging movement by pivotal connections to opposed
parts of the frame, and spring means are provided urging said
frame parts toward one another from a first relationship cor-
responding to a set condition of the trap to a second relation-
ship corresponding to a sprung condition of the trap. The trap
mechanism comprises a system of pivotally connected parts lying
closely parallel and forming the collar which presents the de-
sirable opening to an animal when the trap is in a set condition.
~he pivotally connected parts include co-operating strike means
having paths of movement related to the path of movement of the
frame parts during transition of the trap rom its set to its
sprung state which paths are such that the strike means move
across the plane of the collar opening.
Preferably the strike means comprise two strike bars
pivotally interconnected intermediate their length, the one ends
of the strike bars being pivotally connected to hinge brackets
which form the pivotal connections between the trap mechanism
and the trap frame. The strike bars form a toggle linkage
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proportioned so that it is in a relatively collapsed state
when the trap is in its sprung state and a relatively straiyhten-
ed state when the trap is in its set state. Also connected to
the hinge brackets so as to swing with and in substantially the
same plane as the strike arms is a template forming the collar
and defining the desirable opening. .he template may be formed
in various ways. In one arrangement, the template is formed by
a pair of links suspended one from each hinge bracket and pivotal-
ly secured one to the other at their lower ends to form a stirrup.
The links are formed intermediate their ends with shoulders pro-
jecting towards one another so as substantially to close the open
end of the stirrup and form a collar. In order to complement
the action of the strike bars when the trap is sprung, a further
pair of auxiliary bars forming a second toggle linkage may be con-
nected between points towards the lower end of the stirrup arms,
this toggle linkage being arranged to form an upwardly collap-
sing cradle into which the strike arms press the neck of an
animal being trapped.
In an alternative arrangement, the collar is formed by a
rigid template suspended by links from the hinge brackets so as
- to permit unobstructed movement of the strike bars across the
opening defined b~ the collar. The li~ks supporting the template
may be stirrup arms as previously described.
The invention is described further with a reference to
the accompanying drawings, in which:
Figure 1 is a front elevation of one embodiment of trap
in accordance with the invention, in a set condition,
Figure 2 shows the same trap in a sprung condition,
. Figure 3 is a side elevation of a spring frame used in
the trap of Figures 1 and 2,
Figures 4a and 4b show front and side elevations re-
spectively of an alternative form of spring frame,
Figures 5a and 5b are details in front elevation of an
_ ~ _
11~ 617~
alternative form of trap mechanis~, showing it in set and sprung
conditions respectively,
Fi~ures 6a and 6b are details in front elevation showing
I a further alternative form of trap mechanism in set and sprung
conditions respectively,
Figures 7a and 7b are details showing in front elevation
yet a further alternative form of trap mechanism in set and sprung
conditions respectively,
Figure ~ is a diagrammatic cross section of a trap
showing an animal about to trigger the trap, and
Figures 9a and 9b are front and side elevations of part
of a trap incorporating the mechanism of Figures 5a and 5b,
showing a further alternative form of trigger mechanism.
Referring first to Figures 1 and 2, a trap comprises a
spring frame 20 fabricated from spring steel and comprising a
base spring 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 2, 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 sh~wn
in Figure 1. The end arms themselves (see Figure 3) are formed
- with out-turned side flanges 26 flanking a central ~t7eb 28 having
a central aperture 30. The purpose of this configuration is to
provide arms 24 which are strong and rigid, but at the same time
have a shape which can move through water with a minimum of re-
sistance. 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.
The form of spring shown in Figures 1 to 3 is only one
: of several which could be adopted. One alternative form of spring
is illustrated in Figures 4a and 4b, in which a spring frame 20a
is shown in which the end arms 24a are formed separately from the
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1(~61~S
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base s~ring 22a and curved spring portions 21a, the end arms
extending in the plane of the frame and perpendicular to the
connecting portions of the base spring, to which they are
welded.
A nu~ber of further alternative designs of spring frame
are possible, and several have been tested, although the two
designs described above were found to provide the best com-
bination of performance and ease of fabrication. It would also
be possible to substitute the spring frame by a frame having a
base and end arms hinged thereto, with a separate coil spring
extending between the free ends of the arms so as to urge them
towards one another. Indeed, almost any frame construction
could be used in which two oppositely situated portions of the ~ -
frame which are spring urged towards one another provide support
and motive power for the trap mechanism, provided that the re-
~ mainder of the frame does not obstruct the operation of the trap
- mechanism to be described or an animal's access to the mechanism.
It should be borne in mind that a primary function of the frame is ~.
to support the trap in a desired position,and for this reason
the base spring 22 or 22a, or any equivalent part of the frame
which does not take part in the movement of the end arms, should
be provided with means permitting the trap to be mounted. These
mounting means may take any convenient 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 ~7ill often be provided by the user
of the trap as and when required to position the trap.
Returning to Figures l and 2, the upper ends of the end
arms 24 each support a hinge bracket 30 comprising a clevis 32, a
trigger plate 34 and a pivot pin 36. ~he pivot pin 36 passes -
through the portion 28 of the end arm 26 and is secured in
position by a split pin 3~ passing through the pivot. In order
to assure free movement of the hinge bracket, nylon washers 40
11~6~S
are placed between the split pin and the end arm, and the end arm
and the tri~er plate.
Suspended ~rom the clevises 32 by means of hinges in
the form of clevis pins 42 is a trap m~chanism indicated general-,
ly by the reference numeral ~4.
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 points intermediate their
ends by a further pivot pin 48 forming a fulcrum for the action
of each strike bar and the knuckle joint of a toggle linkage
formed by the two bars 46. Also suspended from each clevis
pin 42 is a curved link 50, the links 50 being connected by a
pivot 52 at their lower ends to form a stirrup when the trap is
in the condition shown in Figure 1. The links 50 are furthe'r'
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 surrounding a jaw 56 forming a de-
sirable opening. In 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 described in more detail herein-
after, two further linke 60 are pivotally connected to the mem-
bers 50 by pivots 62 and to each other by a pivot 64 to provide
a further toggle linkage which forms a cradle indicated general-
ly by the reference numeral 64. The jaw 56 as res'tricted 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 shoulder's of that same'species
of animal. This jaw 56, which is the only opening of substantial
size in the trap, presents a desirable openin~ to an animal
seeking to reach bait placed on the oppo,site side of the trap
to the line of an animal's approach.
The toggle llnkage formed by the strike bars 46 is in
a substantially straightened condition when the trap is in the
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;17X
.
set condition shown in Figure 1~ ith only a small angle between
lines extending from pivots 42 through the pivot 48. The trap is
latched in the set condition by means of a trigger bar 66 t~7hich
is a part of a trigger mechanism which will be described 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 is unlatched from the trigger pin
70, the end arms 24 are urged toward each other through the action ',
of the base spring 22. This results in collapse of the'toggle
linkage formed by the strike bars 46, resulting in strike edges 72
on the strike bars being forced downwardly across the opening of
- the ja~J 56 to deliver a heavy blow to any animal whose'neck ex-
tends through the opening. The strike edges' 72 are curved so as
to continue to act directly downwards across the opening as the
strike bars 46 turn about the pivots 42. Eventually, the strike
bars reach the position sho~n in Figure 2, in which'the free ends
of the strike bars, which are curved, embrace and exert a clamping
action upon the neck of the animal. ~lovement of the'end arms 24
towards one another also results in the members 50 being moved
towards one another, resulting in turn in the co'llapse of the
toggle linkage formed by the links 60 and defining the cradle 62,
the free ends of the arms 60 enhancing the clamping action on the
neck of the animal, and the portions of the links 60 adjacent
to pivots 64 moving upwardly towards the strike edges 72 so as
still further to increase the effect 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 trigger
plate 34 on the hinge bracket 32, the trigger plate being in the
form of a cam configured so that turning movement of the hinge
bracket 30 out'of the plane of the spring frame 20 results in a
lifting movement being imparted to the follo~Jer 74 sufficient
to raise the trigger bar 66 clear of the trigger pin 70. The
form of the cam provided by the trigger plate 74 can be very
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lilV~
simple, and a square plate with its upper corners chamfered is
entirely sa~isfactory.
In use, the trap may be broughtto the set condition shown
in Figure 1 by using any suitable device to spread apart the end
arms 24 sufficiently to enable'a notch 75 on the under edge of the
trigger bar 66 to engage the trigger pin 70. Normally the strength
of the spring 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 screw or hydraulic jack. In
1~ order to secure'the trap in the set position, a safety pin'78 ma~
be provided which is passed through apertures in the strike bars
46 so as to secure them in the relative position shown in Figure
1. At this stage, 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. -'
'I 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 mechanism moves outside the space enclosed within the
spring frame 20, which itself contracts in size as the trap is
sprung. This is a considerable 'advantage, since it much reduces
the likelihood of nearby vegetation or objects obstructing the
operation o~ the' trap, and the overall compact size of the trap
allows it to be used in locations in which many known traps could
not be used, both because'of their overall size and because of
the unobstructed space required around them to enable their free
movement from a set to a sprung condition.
mhe trap is baited by placing a suitabIe bait at some
point beyond the jaw 56 on the opposite side of the trap to the
' expected line of approach of an animal to be trapped. Such an
6~5
animal, in seeking to reach the bait~ will be attracted by the
desirable opening provided ~y the jaw 56 and will pass its head - -
through the opening in an attempt to reach the bait. As pre-
viously described, the jaw is sized so that the shoulders of the
animal cannot pass through the collar formed 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. This will also
result in the trigger plates 38 being turned, and as previously
described, this will result in the trigger bar 66 being lifted
clear of the trigger pin ?, thus springing the trap. The end
arms 24 will then be urged toward one another by the base spring
22 causing the toggle linkage formed by the strike bars 46 to
collapse and the strike edges 72 to be accelerated rapidly
downwards across the jaw 56, thus delivering a violent blow to
the back of the animal's neck at the base of the skull. The
energy storage properties of the spring frame 22 are calcualted
to ensure that, for the species of animal being trapped, the
strength of the blow delivered will be more than adequate to
despatch the animal instantaneously~ However, as a further
assurance the combined action of the free ends 80 of the strike
bars 46 and the links 60 will ensure a squeezing action on the
neck of the animal in itself sufficient rapidly to cause death.
Considerable variation is possible in the form of the
trap mechanism 44. A somewhat less sophi5ticated mechanism is
shown in Figures 5a and 5b, the same reference numerals being
used to identify similar parts. As in the previous embodiment,
strike bars 46 are pivoted to each other and to the pivot 42, but
3~ they are formed as straight bars. The links 50 are also formed
as straight bars and are connected at their lower ends by a chin
plate 80. Although simple to construct, this form of mechanism
has certain disadvantages. Thus the strlke bars have a scissor `
-- 10 --
action as they pclSS from the set to the sprung condition which
is liable to damage the skin of the animal. Thus this form of
mechanism is reall~ only suitable for use in traps for vermin
whose skins are of no value. Moreover the opening 56 is of
rather irregular shape and may be less attractive to animals.
Referring now to Figures 6a and 6b, these show a further
embodiment of trap mechanism in this case similar to that de-
scribed with references to Figures 1 and 2 except for the
omission of the links 60 forming the cradle 62. The remaining
components are identical in function to those described t~ith re-
ference 1 and 2 and are indicated by the same reference numerals.
However the configuration of the strike bars 46 the shoulders
54, and the members S0 has been altered so as to avoid the neces-
sity for providing the links 60 in order to provide a jaw opening
of appropriate dimensions. As compared with the arrangement shown
in Figures 1 and 2, it has the advantage of greater simplicity
but it is less easy to adapt the structure for animals of dif-
ferent species, and the clamping action on the neck of the animal
when the trap is in the sprung condition is less satisfactory.
A further form of trap mechanism is shown in Figures 7a
and 7b in which parts which are common to the mechanism shown in
Figures 1 and 2 are again referred to by the same reference numer-
als. In this embodiment the strike arms are configured and arrang-
ed as in the embodiment of Figures 1 and 2, but the collapsible
template formed by the members 50 is replaced by a rigid template
82 suspended from the pivots 42 by links 84. The template has
an external outline such that it does not foul the spring rame
20 when the trap is in its sprung condition and a central aperture
86 which presents a desirable opening to a species of animal to
be trapped. At least the lower edge of the aperture 86 is pro-
vided with a smoothly finished lip 88 in order to avoid the
possibilitv of damage to an animal's pelt when the trap is sprung.
As 1n the previous embodiments, the template forms a collar
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1~617S
.
against which the animal presses its shoulders in attempting to
reach the bait, the resulting pressure on the template being trans-
mitted through the links 84 to the hinge brackets 30 to trigger
thetrap as previously described. In order to adapt the trap for
animals of different species it is only necessary to exchange
the template 82 for one having an aperture 86 of the appropriate
di~ensions.
Referring now to Figure 8, there is shown in a highIy
diagrammatic manner an animal 90 with its head 92 inserted through
the aperture 56 of the mechanism of a trap, which for the sake
of illustration only is taken to be that of Figures 1 and 2. The
animal shown in Figure 8 has just sprung the trap and the strike
bars 46 are shown descending onto the back of its neck. If the
strike bars 46 and members 50 are spaced somewhat apart as shown
in the Figure, by installing spacers between them on the clevis
pins 42, the trap can be caused to operate so that the squeezing
action on the animals neck as the trap reaches its fully sprung
condition is replaced by a neck breaking action. It is however
important that the strike bars and stirrup shbuld not be too far
apart, or that during springing of the trap they should not be
permitted to spread too far apart due to play at the various
pivots. If this occurs, the animal, particularly if it is of a
very sinuous species such as mink, may be able to pass between
the components of the trap mechanism to a greater or lesser extent,
with the possibility of the animal being injured or severely
frightened instead of being killed. In order to avoid this, those
embodiments of trap mechanism incorporating the links 50 may be
provided with an additional member or members 50 which extend be-
tween the pivots 42 and 52 adjacent one or both the original pair
of members 5~, but on the opposite side of the strike bars 46.
This arrangement avoids the possibility of parts of the trap
mechanism moving appreciably out of the plane of operation of the
mechanism. In the case of the embodiment of Figure 7, twin
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~mplates,connect~d at their bottom edges may be employed.
Variations of the tric~ger mechanism employed in the embodi-
ment of Figures 1 and 2 are possible. Referring to Figures 9a and
9b there is shown a simplified form of trigger mechanism applied
to a trap incorporating the mechanism of Figures 5a and 5b (al-
though it would be equally applicable to the other mechanisms de-
scribed). The trigger components previously described are all
omitted, and instead a latch stop 94 is formed on one of the end
arms 24. The end of the strike bar 46 is extended so that when
the end arms of the spring frame are drawn apart, it can be rested
on the latch stop 94. When an animal causes the trap mechanism
to turn about the pivots 3~ of the hinge brackets 30, the end of
the strike bar is shifted off the latch stop 94 and the trap is
sprung. The advantage of this arrangement is its extreme sim-
plicity, but it is less sensitive than the arrangement previously
described since the pressure from the spring frame is transmitted
through the strike bars 46 to the stop 94, resulting in the various
pivots in the trap mechanism being placed under load. This in-
creases the friction in the mechanism and makes the triggering
action less sensitive and less predictable.
All the trap mechanis~sdescribed have employed the toggle
action strike mechanism which is disclosed in co-pending United `
States patent application no. 792,533 filed May 2, 1977 in
the name of Armand Jacob. However the invention can be applied
to traps incorporating other types of trap mechanism in which
the means for striking across the jaw or opening formed in the
mechanism is of a different construction. For example, if it is
of no importance to preserve the pelt of the animal, strike means ;
in the form of a guillotine can be utilized
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