Note: Descriptions are shown in the official language in which they were submitted.
jo/ks
1;~37~5
A lifting hook.
The present invention concerns a lifting hook for auto-
matic release of a load held by the lifting hook, compri-
sing a hook member with a hooking portion and a suspension
portion as well as an intermediate portion between said
portions, a suspension means which at least when the
hooking portion is loaded is pivoted in the suspension
portion and suspended by a traction element, e.g. a chain
or the like, and a latch, which is pivoted in a bearing
arranged in the suspension portion and which obstructs
the opening of the hook, said intermediate portion compri-
sing, preferably all along its length, a slot receiving
the bearing of the suspension means, so that this is
displaceable in said slot and so that the hook member,
when the traction element is unloaded followed by a lifting
of the hook member, is turned from an ordinary load-
carrying position to a load-releasing position by dis-
placement of the centre of gravity of the lifting hook.
A lifting hook of the type mentioned above is described
in the English patent 1 284 851. However, this lifting
hook comprises some disadvantages. The greatest disad-
vantage of this lifting hook consists in the fact that
the hooking of a load is comparatively complicated, since
the whole hook member has to be pivoted upwardly/back-
wardly a~ the same time as the means closing the hook
opening has to be held aside when the load lug is inserted.
Another disadvantage of this known lifting hook consists
in the fact that the location of the centre of gravity
is unfavourable, through which it is necessary to pro-
vide the hook with an assisting turning means, which
is arranged in the lower portion of the hook and consists
of a rope or the like for causing the turning to take
place, in order to obtain a lifting hook fairly safe
in operation. However, this unfavourable weight distri-
bution of the hook cannot simply be modified, since this
would imply a still more unstable position of the lifting
hook when this is hanging freely.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a lif-
ting hook of the kind mentioned above, which overcomes
the drawbacks and the disadvantages of the known lifting
hook mentioned above.
This object is obtained according to the invention by
the fact that the latch is affected by a spring in the
closing direction, that the bearing of the latch is dis-
placeable in a slot in the suspension portion of the
hook member and affected by the spring in a direction
towards an end position in the slot, so that the latch,
in the non-load-releasing position, resiliently bears
against the suspension means, and so that the latch is
hanging freely in the load-releasing position.
A lifting hook according to the invention does in this
way give the advantage to enable a very easy hooking
of the load on the hook. Another advantage consists in
the fact that the lifting hook is very stable in a position
before the lifting hook is loaded.
Further objects and advantages will appear from the appen-
ded dependent claims.
BRIEF DESCRIPTION OF THE DRAWINGS
With reference to the drawings the invention will herein-
after be described more in detail by way of embodiment
examples.
In the drawings:
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Fig 1 is a perspective view obliquely from above of the
lifting hook according to the invention, in a state without
load and with the latch in closing position.
Fig 2 is a side-elevation of the lifting hook according
to fig 1, but with the latch in a position opened for
hooking of the load.
Fig 3 is a side-elevation of the lifting hook according
to fig 2, but with load and with the latch in the closing
position.
Fig 4 is a side-elevation of the lifting hook without
load and with the hook member in the beginning of its
turning.
Fig 5 is a perspective view obliquely from above of the
lifting hook according to the invention, in a state without
load and with the latch in the releasing position and
with the hook member completely turned.
Fig 6 is a perspective view obliquely from above of a
second embodiment of the lifting hook according to the
invention, in a state without load and with the latch
in a closing position.
Fig 7 is a lateral cross section view of the lifting
hook according to fig 6 along one lateral surface of
the hook member, with the lifting hook in a state without
load and with the latch in the closing position.
Fig 8 is a cross section view of the lifting hook accor-
ding to fig 7, but with the latch in the position ope-
ned for hooking of a load.
Fig 9 is a cross section view of the lifting hook accor-
ding to fig 7, but loaded and with the latch in the clo-
sing position.
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Fig 10 is a cross section view of the lifting hook without
load and with the hook member in the beginning of its
turning.
Fig 11 is a cross section view of the lifting hook with
the latch in the releasing position and with the hook
member completely turned.
DET~ILED DESCRIPTION OF PREFERRED EMBODIMENTS
A half-automatic lifting hook for automatic release of
objects held by the lifting hook is shown in figs 1-5.
The lifting hook comprises a hook member 1 with a hooking
portion 2 and a suspension portion 3 as well as an inter-
mediate portion 4 between said portions 2, 3, a suspen-
sion means 5, which when the hooking portion 2 is loaded
~see fig 3) is pivoted in the suspension portion 3 and
suspended by a traction element in the form of e.g. a
chain engaging the hole 6.
The inwardly turned face 24 of the hooking portion 2
has a flat section 25 which is located substantially
horisontally when the lifting hook is lifted. Thanks
to this no unsuitable uneven load on the band will occur
in the present lifting hook during the lifting of flexible
wide bands, but the band will be loaded uniformly over
its whole width.
The lifting hook is provided with chamferings 27 and
smoothed guiding faces 26 in order to avoid undesireable
hookings.
The intermediate portion 4 of the hook member l is along
its substantially entire length provided with a slot
7. The slot 7 extends right to a bearing 8 of the sus-
pension means 5 and receives this bearing so that it
is displaceable in said slot 7. The hook member l is
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then arranged to, when the traction element is unloaded,
followed by a lifting of the hook member 1, be turned
from an ordinary load-carrying position (fig 3) to a
load-releasing position (fig 5) by displacement of the
centre of gravity of the lifting hook.
In the embodiment of the present invention shown in fig
1-5 the lifting hook comprises a latch 9, which obstructs
the opening 10 of the hook and which is pivoted in the
suspension portion and affected by a spring 11 in the
closing direction (see fig 1 and 3). The bearing 12 of
the latch 9 is arranged generally in parallel with the
bearing 8 of the suspension means and displaceable in
a slot 13 in the suspension portion 3 of the hook member
1 and affected by the spring 11 towards an end position
14 in the slot 13, since the spring 11, which has the
shape of a helical compression spring, is received within
a hole 15 arranged in the suspension portion 3 and in
alignment with the extension direction of the slot 13.
Through this the spring 11 acts between the bearing 12
and a stop member 16 screwed into the hole 15, the spring
force generated by the spring being adjustable by means
of said stop member through modification of the screwing
depth in the suspension portion 3.
The suspension means 5 comprises a pin 17 which is paral-
lel to the bearings 8 and 12 and is arranged to go into
engagement with a recess 18 in the suspension portion
3 of the hook member 1. When the pin 17 is in engagement
with the recess 18 the suspension means 5 is without
pivotability with respect to the suspension portion 3
and the spring 11 holds the pin 17 in the recess 18 owing
to the fact that the latch 9 resiliently bears against
the suspension means 5. Thus, the spring 11 holds the
three essential parts (the hook member 1, the latch 9
and the suspension means 5) together and prevents them
from moving with respect to each other when the pin 17
is in engagement with the recess 18.
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The latch 9 comprises a first edge side 19 which resi-
liently bears against a first edge surface 20 of the
suspension means 5 when the latch is in the closing posi-
tion, and a second edge surface 21, which, when the latch
9 is in the position opened for hooking of a load, resi-
liently bears against the first edge surface 20 of the
suspension means 5, when the pin 17 is in engagement
with the recess 18. The latch 9 is operated by hand bet-
ween the closing position and the position opened for
hooking of a load. The edge surfaces 19, 21 of the latch
9 and the transition portion 22 between these are so
designed that the spring is most compressed when the
transition portion bears against the first edge surface
20 of the suspension means 5 and that the latch 9 is
self-holding in a position open for hooking of a load
(see fig 2).
The suspension means 5 is pivotable with respect to the
suspension portion 3, when the pin 17 is in engagement
with the recess 18, and the first edge surface 19 of
the latch 9 is then (see fig 3) bearing against a second
edge surface 23 of the suspension means 5 as long as
the traction element is not unloaded and stretched again.
The lifting hook described in fig 1-5 operates in the
following way. In a state shown in fig 1 the lifting
hook is prepared to be employed for a lift. The latch
9 of the lifting hook is then moved by hand to the posi-
tion shown in fig 2. Through this it is now possible,
without holding the latch 9, to introduce a leash, a
band or the like through the hook opening 10 for recei-
ving it on the hooking portion 2. After this the latch
9 is moved down to the closing position and the lifting
hook is lifted through the traction element, through
which (see fig 3) the pin 17 goes out of engagement with
the recess 18. The latch 9 is in spite of this in the
closing position, since the spring 11 is pressing the first
edge surface 19 of the latch against the second edge
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surface 23 of the suspension means 5. After the load
has been moved to a determined place the lifting hook
is lowered so that the traction element is unloaded be-
cause the hooking portion of the hook member 1 is laid
against the load. Thanks to the location of the centre
of gravity of the lifting hook this implies a displacement
of the hook member 1 along its slot 7 and a turning of
the hook member 1 of substantially 180 from the posi-
tion in fig 3 through the position in fig 4 and to the
position in fig 5, where the hook opening 10 is turned
substantially straight downwardly, so that the leash
or the chain easily can slide out of the hook opening
10, since the latch is hanging free right downwardly
without influence by the spring in any direction abGut
the bearing 12. The bearing 12 is at this moment in its
end position 14.
In order to bring the parts 1, 5 and 9 together to the
position for receiving a load (see fig 2), one has to
grasp the hook member 1 by hand and turn it back from
the position in fig 5 through the position in fig 4 to
the position in fig 3, and insert the pin 17 in the recess
18, as appears from fig 2, by compressing the spring
11 and subsequently pivoting the latch 9 up to the position
in fig 2.
In fig 6-11 another embodiment of the hook according
to the invention is shown, where the latch is not only
spring-loaded in the closing direction, but also positively
locked in the closing position when the lifting hook
is lifting a load. This embodiment of the hook according
to the invention will only be described as far as it
differs from the embodiment of the lifting hook according
to the invention already described, and parts in this
embodiment which have the same or a similar function
as corresponding parts in the embodiment already described
will here be numbered in the same way.
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The lifting hook according to this embodiment differs
from the embodiment previously described by the fact
that the slot 13 in one end position 14, towards which
the spring 11 tends to press the bearing 12, is widened,
so that the bearing 12 gets a play substantially trans-
versely to the extent of the slot. Closer to the other
(the second) end position in the slot, i.e. closer to
the member 16, there is also a corresponding widened
space 29. However, the slot 13 extends beyond this widened
space 29 and closer to the member 16. The widened spaces
28, 29 are provided in the upper portion of the slot
as it is orientated in the figures 7-9. The slot 7 in
the intermediate portion 4 of the hook member 1 has also
a widened space 30 in which the bearing 8 of the suspension
means is located in the ordinary load-carrying position.
The lifting hook according to this embodiment differs
from the embodiment previously described also by the
fact that the latch comprises a shoulder portion 31 ar-
ranged on the free end of the latch 9. This portion can-
not always simply pass the point 32 of the hook member.
A further difference between the two embodiments consists
in the fact that in the embodiment according to figs
6-11 the latch 9 has the edge surface 19 bearing against
the edge surface 20 as well as the edge surface 23 on
the suspension means 5, when the lifting hook is in the
ordinary load-carrying position (see fig 9). In the state
of the lifting hook in accordance with fig 7 there is
besides the bearing of the edge surface 20 against the
edge surface 19 of the latch, also a portion 36 of the
latch 9 bearing against the intermediate part 4 of the
lifting hook, so that the closing moment on the latch
9 about the contact surface between the edge surface 19
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of the latch 9 and the edge surface 20 of the suspension
means 5 on the latch 9 and caused by the spring 11 is
counteracted.
The lifting hook described in fig 6-11 functions in the
following way. In a state shown in fig 7 the lifting
hook is prepared to be employed for a lifting operation.
The latch 9 of the lifting hook is then moved by hand
to the position shown in fig 8. The latch 9 is arranged
to be self-holding in this open position owing to the
fact that the edge surface 21 of the latch 9 resiliently
bears against the edge surface 20 of the suspension means.
The bearing 12 of the latch has during the opening move-
ment of the latch 9 moved in the direction from the end
position 14 towards the member 16. More exactly the bearing
12 has moved from the position shown in fig 7 substan-
tially straightly below the widened space 29 in the slot
13 to the space 33 in the slot 13. Thanks to the fact
that the edge surfaces 19, 21 of the latch 9 and the
transition portion 22 between these are so designed that
the spring 11 is mostly compressed when the transition
portion 22 bears against the first edge surface of the
suspension means 5, so that the latch 9 is self-holding
in the position opened for hooking of a load, also a
certain end movement of the bearing 12 in the direction
towards the end position 14 is taking place after the
transition portion 22 has passed the first edge surface
20 of the suspension means 5. It is now possible to intro-
duce a leash, a band or the like through the hook ope-
ning 10 for reception on the hooking portion 2 without
holding the latch 9. Subsequently the latch is moved
down to the closing position and the latch is then allowed
to, beside the pivoting, carry out a lifting movement,
since the bearing moves upwardly into the widened space
29, so that the shoulder portion 31 on the latch can
pass the hook point 32. After this the lifting hook is
lifted through a traction element, through which (see
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1 o
fig 9) the pin 17 goes out of engagement with the recess
18, and through which the bearing 8 of the suspension
means 5 is lifted upwardly into the widened space 30
in the slot 7 of the hook member 5. During this relative
movement between the hook member and the suspension means
also a displacement of the bearing 12 from the position
of fig 7, where it is substantially straight below the
widened space 29, to a position between the two widened
spaces 28, 29 is taking place. In this position there
is no possibility to lift the latch, so that the shoulder
portion 31 can pass the point 32 of the hook member,
since the slot in the portion 34 between the two widened
spaces 28 and 29 receives the bearing 12 without any
clearance. In this load-carrying position of the lifting
hook as well as in all other positions with exception
for the load-releasing position of the lifting hook,
the spring 11 presses the latch towards the suspension
means 5. In the positions shown by fig 7 and 8 the co-
operation of the pin 17 with the recess 18 generates
the force opposed to the spring 11, while in the position
according to fig 9 the cooperation of the bearing 8 with
the widened space 30 in the slot 7 generates the force
acting against the spring 11 and preventing the suspension
means and latch from being separated from each other.
After the load has been moved to a determined place,
the lifting hook is lowered, so that the traction element
is unloaded by laying the hooking portion of the hook
member 1 on the load or on an underlayer. In doing so
the bearing 8 of the suspension means goes out of engage-
ment with the widened space 30 in the slot 7, so that the
suspension means and the latch are separated from each
other at the same time as the bearing of the suspension
means starts to move along the slot 7 and at the same time
as the bearing 12 of the latch 9 is pressed in the direc-
tion of the end position 14. In this end position 14
the widened space 28 is so arranged that the bearing
12 goes away from the hook point 32 to such an extent, that
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the shoulder portion 31 of the latch can pass the hook
point by the fact that the latch is turned about the
bearing 12 and the hook member 1 is turned substantially
180 from the position in fig 9 through the position
in fig 10 and to the position in fig 11, where the hook
opening 10 is turned substantially right downwardly,
so that the leash or the chain can slide out of the hook
opening owing to the fact that the latch is hanging
freely right downwardly without any essential spring
influence in any direction about the bearing 12. The
~earing 12 goes away from the hook point 32 and goes
up in the widened space 28 owing to the fact that the
shoulder portion 31 is provided with an appropriately
inclined surface 35 which slides over the hook point
32 through the weight influence of the latch 9. Some
assistance can also be obtained through the spring 11
which can be allowed to affect the bearing 12 upwardly
in the widened space 28 thanks to the fact that the slot
13 more or less is provided with a guiding part towards
the widened space 28. At this automatic turning the latch
9 causes a very favourable displacement of the centre
of gravity of the lifting hook, which results in the
elimination of the risk of a non-appearance of turning
of the hook member.
