Note: Descriptions are shown in the official language in which they were submitted.
1~92968
CONTAINER AND TRAIIER DLING C~OMBINATION YOKE DEVICE
WITEI INPROVED l~E~ATED STORAGI~ FOR LII~ING AR~IS
BACKGROUND OF THE INVENTION
The invention relates to a device for swinging the
lifting arms of a container and trailer-handling
combination yoke device upwards, and transfer thereof to
a position inside the perimeter of an imaginary
rectangular figure resulting from drawing imaginary
lines joining the laterally outer ends of respective
long sides of the yoke means of the device, when
containers and trailers are being handled. Such a
location of the lifting arms of the combination yoke
device inside the long sides of the yoke means is of the
greatest importance when using the yoke means for
handling containers, during which the yoke means
supports the container at each of the four corners of the
top of the container by means of so-called twist locks,
especially in the case when a close arrangement of
containers in, for example cargo terminals is desired for
space reasons, which has, of course, great economic
advantages.
A device of this type is already known. In the
known device, the lifting arms are first swung upwards by
means of a conventional hydraulic cylinder, the piston
rod of which is attached to the lifting arm and the
cylinder of which is attached to an intermediate piece in
which the arm is pivotably suspended, to a substantially
horizontal position, after which the intermediate piece,
with the upwardly swung arm and the hydraulic cylinder,
is pulled-in to a position in~ide the long side of the
yoke means, by means of another conventional hydraulic
cylinder arranged on a stationary transverse beam
included in the frame in which a movable beam is arranged
telescopically, said intermediate piece being attached to
said movable beam.
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A disadvantage of this known device is that the
lifting arms in an upwardly swung, pulled-in position
will not remain in this position due to the fact that the
hydraulic cylinders have a tendency to leak hydraulic
liguid, allowing the arms to sink from their horizontal
position.
This sinking which, moreover, is accelerated by the
violent movements of the yoke means in handling and, of
course, may be as great for different arms, may result
in the lifting arms getting in contact with one another
and sometimes, moreover, to hook to and lock each other
and, which is very common, the lifting arms knocking a
hole in the container or the trailer which, for example,
in a following rain may have devastating effects on the
contents of the container or trailer. Such damage to
thecontainer or trailer must be repaired immediately
resulting in a stoppage of the handling work which,
conse~uently, involves losse6 of both time and money.
Another disadvantage is the bad moderation of the
swinging movements of the lifting arms in the
longitudinal direction of the yoke means, for example due
to an unevenly distributed load in the container or in
exact operation of the yoke means caused by the
conventional single piston-type hydraulic cylinders of
the lifting arms in handling which may result in a
displacement of the load, damage to the load in the case
of a fragile load or to the very yoke means, trailer and
container.
SUMMARY OF THE INVENTION
Consequently, it is the object of the present
invention to provide a means for swinging lifting arms of
such a combination yoke device upwards and for
transferring the lifted arms to a position inside the
long sides of the yoke means, when containers or trailers
are being handled, said device eliminating the
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disadvantages in the known devices described above.
This object is achieved by means of the device
according to the invention which is characterized in that
it comprises a first shaft for swinging the lifting arm
upwards from a vertical position to a substantially
horizontal one and back, and a second, substantially
horizontal shaft around which the first shaft is
pivotable, together with the lifting arm, for swinging in
and out, transversely of the longitudinal axis of the
device, the upwardly-swung, substantially horizontal
shaft to a position inside and outside, respectively, the
long side of the yoke means.
The device is characterized, moreover, in that the
first shaft is inclined somewhat downwards relative to
the horizontal plane to the right or to the left, when
the associated lifting arm is in its swung-up, swung-out
position, that the second shaft is inclined somewhat
downwards or upwards relative to the horizontal plane, or
that both the ~irst and second shaft6 are horizontal,
that the first shaft and the second shaft are arranged
substantially perpendicularly to each other, that the
~irst shaft connects the lifting arm with an intermediate
piece and that the second shaft connects the intermediate
piece with the yoke means pivotably
Furthermore, the lifting arms can be arranged at the
ends of a frame included in the yoke means or at the ends
of the transverse beams of the yoke means.
For swinging up the lifting arm and swinging in the
intermediate piece and the lifting arm the device of the
invention preferably comprises a hydraulic double
cylinder, one piston rod of which is connected to the
intermediate piece and the other piston rod with the
lifting arm, and a hydraulic cylinder connecting the
intermediate piece with the yoke means.
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BRIEF DESCRIPTION OF THE DRAWINGS
The invention is described below in greater detail
in the form of an example with reference to the attached
drawings, wherein
FIG. 1 is a schematic perspective view of the device
of the invention when handling a trailer, the carrying
arms being shown in a swung-down, operating position,
FIG. 2 is a schematic perspective view of the device
of the invention when handling a container, the carrying
arms being shown in a swung-up, swung-in stowed (stored)
position,
FIG. 3 is a schematic enlarged scale, fragmentary
end elevational view of the intermediate piece of the
device of the invention and shows how the piston rod of
the hydraulic cylinder and the lifting arm are connected
to this intermediate piece, and
PIG~ 4 is a schematic diagram of the hydraulic
double cylinder with its associated control circuit used
in the device of the invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
As is apparent from the drawings, especially FIGS. 1
and 3, the device of the invention comprises horizontal,
longitudinally-extending frame, in the opposite ends of
respective channels of which respective longitudinal
beams 6 are telescopically received for greater and
lesser extension (as shown in FIG. 1), and retraction (as
shown in FIG. 2). At its outer end, each longitudinal
beam mounts a respective transversely extending beam or
: yoke ~0, having outer ends 22. Each yoke is shown
provided with elements 24 for engaging a trailer or
::~ container for effecting handling. The device further
comprises at each end of each yoke 20, an intermediate
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piece 4 with a first shaft 1 fixedly mounted therein, to
which a lifting arm 2 of the device is mounted and around
which that lifting arm can be swung upwards, from being
generally vertical to being generally horizontal, so as
to become substantially in parallel with the longitudinal
axis of the device. The raising of the lifting arms is
effected by pivotal movement of the lifting arms around
the longitudinal axes of the respective first shafts 1,
at a time when the first shafts are disposed generally
horizontally and transversely of the longitudinal axis of
the device, at the upper ends of the lifting arms, each
position by means of a respective hydraulic double
cylinder 8, i.e., a piston-cylinder unit having a
cylinder from which two independently extensible-
retractable pistons extend in axially opposite
directions. When the lifting arms are arranged
vertically, as shown in FIG. 1, one piston rod of each
unit 8 is an upper one, and the other i8 a lower one. In
each unit, the upper piston rod is articulatedly
connected to a pair of lugs 10 on the respective
intermediate piece and the respective lower piston rod is
articulatedly connected with a pair of lugs 11 on the
respective lifting arm 2. Each intermediate piece 4
comprises further a sleeve 9 in which a second,
substantially horizontal shaft 3, attached to the
respective yoke end Z2 is received, and around which the
respective intermediate piece 4 with the respective
lifting arm in a substantially horizontal position, can
be swung medially, inwards (in relation to the
longitudinal axis of the frame 5) into the position shown
in FIG. 2 by means of a respective conventional hydraulic
cylinder 7, the piston rod end of which is rotatably
connected to a second pair of lugs 12 on the respective
intermediate piece.
As mentioned above, both the first shafts 1 and the
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second shafts 3 are generally horizontal when the lifting
arms are in their respective generally vertical,
operating positions. It should be understood by this
that the first shaft can be somewhat inclined downwards
relative to horizontal to the right or to the left or
that the second shaft can be inclined somewhat upwards or
downwards relative to horizontal. of course, the two
shafts 1 and 3 can also be substantially horizontal, one
lifting arm on each side lying transversely inside the
other lifting arm on the same side of the device, in the
same horizontal plane. In order that the lifting arms 2,
when disposed in an upwardly swung position might be
swung in at each long side of the yoke means, in a spaced
relationship, the second shafts 3 at one end of one yoke
means 20 at both ends 22 thereof at one end of the
device, for example, can thus be mounted so that they are
somewhat inclined downwards from the horizontal plane and
at the other end of the device both ends 22 of the yoke
20 the second shafts 3 may be mounted the yoke means so
that they are inclined somewhat upwards from the
horizontal plane ~see FIG. 2).
If each intermediate piece 4 is swung inwards to
such a position that the respective shaft l is vertical,
there is no turning point around which the respective
lifting arm, upon the occasion of leakage of hydraulic
liquid from the respective double cylinder 8, can turn
and, consequently, by the device of the invention sinking
of the lifting arm and the associated damage described
above in connection with the prior art device are
eliminated by means of the device of the invention.
However, each first shaft 1 is, in the preferred
embodiment, inclined in its final position, as shown in
FIG. 2, somewhat inwards from the vertical plane against
the yoke means and consequently the lifting arms and the
intermediate pieces will exert a torsional movement about
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the second shafts 3 in this position. Howeverl the small
torsional movement concerned here is absorbed by the
hydraulic cylinders 7, the pistons of which are quite
retracted in this position.
The above-mentioned double cylinder 8 shown in FIG.
4 is used with the d~vice of the invention instead of a
conventional hydraulic cylinder primarily to improve
damping of the tensile forces arising in the course of
the upwardly-directed pivotal movements of the arms,
which can bring several problems as mentioned in the
introductory portion of the specification. In principle,
each double cylinder 8 has three positions, viz both
pistons retracted, the upper piston retracted and the
lower piston pushed out and both pistons pushed out. In
the present case only the two first positions are used.
In the first position the respective lifting arm is in an
upwardly-swung, substantially horizontal position and in
the second position, each lifting arm 2 is in its
vertical lifting po~ition (FIGS. 1 and 4). Damping can
be e~fected in the following way: at an inwardly directed
pivotal motion o~ the lifting arm the double cylinder
will be exposed to a compression force that is damped by
the lower piston as in a usual hydraulic cylinder with a
piston, while the double cylinder at an outwardly
directed pivotal motion of the l~fting arm, i.e., in a
direction towards the end section of the yoke means, will
be exposed to a tensile force that is damped by the upper
cylinder. A preferred control circuit, shown used with
the two double cylinders in FIG. 4 comprises the
following components: two adjustable overflow valves 13,
14, a directional valve 15, a safety valve 16, a non-
return valve 17, a pump 18, a tank 19 and conduits for
the hydraulic liquid. The fundamental structure of the
control circuit is, of course, the same independently of
the number of double cyli~ders. Thus, by using a double
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cylinder, damping of the tensile forces at the outward
motion of the lifting arm is also achieved in addition to
the usual damping of the compression forces at the inward
motion of the lifting arms. This is not without
importance, as the motion forces can amount to lOO,OOON
and more.
Thus, by means of the device of the invention, both
a more efficient utilization of the storage surfaces of
the cargo terminals and a safer handling of trailers both
for humans and surroundings can be obtained.
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