Note: Descriptions are shown in the official language in which they were submitted.
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HYDRAULIC SHOVEL LIFTING JIG
TECHNICAL FIELD
The present application relates to a lifting jig connectable to a
hydraulic shovel to facilitate lifting operations thereof.
BACKGROUND ART
From time to time, hydraulic shovels need to be lifted for servicing
purposes. For instance, the superstructure (upper part) of a shovel may need
to be
separated and lifted from the truck below (lower part) to remove the truck
from
underneath the shovel. For instance, the superstructure may be lifted from the
truck to
provide access to the hydraulic shovel's rolling circle, which needs to be
serviced at
intervals. To do so, the superstructure (upper part) is separated from the
truck. This
operation requires a lot of time and effort and in doing so; there is a great
advantage
to the owner if the lifting method utilized does not involve dismantling of
the shovel's
front attachments.
SUMMARY
It is a feature of the present invention to provide a lifting jig which
permits the front attachments of a hydraulic shovel to remain attached to the
superstructure while the superstructure is lifted from its truck thereunder.
Another feature of the present invention is to provide a method of
safely lifting a superstructure of a hydraulic shovel above a truck thereof
with the
front attachments of the shovel secured to the superstructure.
According to the above features, from a broad aspect, there is provided
a lifting jig to safely maintain front attachments of a hydraulic shovel
engaged to a
superstructure while lifting the superstructure above a truck. The lifting jig
has a
body member having a jig fixation hole in a lower section thereof for
securement to a
pivot attachment of a boom cylinder lower end disconnected from the pivot
attachment. A lug is formed in the body member spaced above the boom cylinder
attachment hole for securement of the boom cylinder lower end. The body member
further has a horizontal surface disposed to receive a lifting force and a
thrust surface
to transfer the load from the front attachments to the superstructure.
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According to a further broad aspect, the lifting jig may also be secured
to the superstructure with the front attachments removed to lift the
superstructure
from the truck for servicing.
According to a further general aspect, there is provided a hydraulic
shovel comprising a superstructure mounted to a truck, a lifting jig having a
body
member mounted at a lower end section thereof to an existing pivot attachment
of the
superstructure, and front attachments mounted to the superstructure, the front
attachments including a boom cylinder having a lower end pivotally connected
to an
upper end section of the body member of the lifting jig, the lifting jig
further having a
front nose defining a downward-facing surface disposed to receive a lifting
force, and
a thrust surface at a back end portion of the body member of the lifting jig
in bearing
contact with a corresponding bearing surface of the superstructure, wherein
the boom
cylinder has an axis, and wherein the axis of the boom cylinder extends
rearwardly of
the existing pivot attachment for a full range of motion of the boom cylinder,
thereby
preventing the lifting jig to pivot away from the corresponding bearing
surface of the
superstructure.
According to a further general aspect, there is provided a lifting jig for
securement to a boom attachment of an hydraulic shovel having a superstructure
mounted to a truck, the lifting jig comprising: a body member having a jig
fixation
hole in a lower section thereof for securement to an existing pivot attachment
of a
boom cylinder lower end in a forward section of the superstructure, a lug
formed in
said body member spaced above said jig fixation hole for pivotal connection
with the
boom cylinder lower end, said body member further having a front nose defining
a
downward-facing surface disposed to receive a lifting force, and a thrust
surface
provided at a back end portion of the body member rearwardly from the jig
fixation
hole for bearing engagement with a corresponding bearing surface of the
superstructure, the body member being configured so that when the boom
cylinder is
retracted, the downward-facing surface projecting generally horizontally in
front of
the superstructure when the thrust surface is engaged with the corresponding
bearing
surface of the superstructure.
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According to a another further general aspect, there is provided a
method of lifting a hydraulic shovel having a superstructure mounted to a
truck and
front attachments mounted to the superstructure, the front attachments
including a
boom operated by a boom cylinder; the method comprising: disconnecting a lower
end of the boom cylinder from a pivot attachment secured to said
superstructure;
mounting a lifting jig to said pivot attachment; pivotally mounting said lower
end of
the boom cylinder to a lug of said lifting jig, the lug being spaced above the
pivot
attachment; transferring a load of said front attachments to said
superstructure
through a thrust surface of said lifting jig; and applying a lifting thrust to
a front
horizontal surface of said lifting jig with said boom cylinder of said front
attachments
fully retracted, said lifting thrust being synchronized with other lifting
thrust applied
to said superstructure.
According to a still further broad aspect of this invention, there is
provided a method of safely lifting a superstructure of a hydraulic shovel
above a
truck thereof with front attachments secured to the superstructure. The method
comprising the steps of:
i) disconnecting a lower end of one or two boom cylinders of the
front attachments from a respective pivot attachment secured to the
superstructure,
ii) securing a lifting jig to the pivot attachments,
iii) securing the lower end to a lug of the lifting jig spaced above
the pivot attachments,
iv) transferring a load of the front attachments to the superstructure
through a thrust surface of the lifting jig, and
v) applying a lifting thrust to a horizontal surface of the lifting jig
with the one or two boom cylinders and arm cylinders of the front attachments
fully
retracted, the lifting thrust being synchronized with other lifting thrust
applied to the
superstructure.
According to a still further broad aspect the method comprises
securing the lifting jig to the superstructure with the front attachments
removed to lift
the superstructure above the truck for servicing.
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BRIEF DESCRIPTION OF THE DRAWINGS
The preferred embodiment of the present invention will now be
described with reference to the accompanying drawings in which:
Figure 1 is a side view of a hydraulic shovel of a type well known in
the art;
Figure 2 is a side view of the shovel of Figure 1 but showing a lifting
jig secured to the shovel superstructure and attached to a boom cylinder of
the front
attachments.
Figure 3 is a side view similar to Figure 2 and illustrating the
superstructure in a lifted position by the lifting jig with the front
attachments having
been removed whereby to service the shovel;
Figure 4 is a side view similar to Figure 2 illustrating the
superstructure and the front attachments lifted from the truck and the
position of jacks
to apply a synchronized lifting force to the superstructure and the lifting
jig;
Figure 5 is a side view illustrating the construction of the lifting jig;
Figure 6 is a front view of the hydraulic shovel illustrated in Figure 1
with a lifting jig secured in position and connected to the lower end of a
pair of boom
cylinders; and
Figure 7 is a front view similar to Figure 6 showing the superstructure
and its front attachments lifted from the truck and illustrating where the
lifting forces
apply.
DETAILED DESCRIPTION
Referring now to the drawings and more particularly to Figure 1, there
is shown generally at 10 a hydraulic shovel of a type well known in the art.
It
comprises a superstructure 11 secured to a truck 12 having an endless track 13
to
displace the shovel on a ground surface. A rolling circle 14 is secured
between the
truck and the superstructure 11 to permit the superstructure to revolve 3600
around
the central axis 40 of the shovel in either direction left or right. In the
front of the
superstructure is mounted the front attachments 15 which may consist of a boom
16,
an arm 17 and a connector flange 18 secured to a bucket 19. The boom 16 is
articulated on a pivot 20 by a boom cylinder 21, which is herein shown fully
extended
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and secured at a lower end 22 to a pivot attachment 23. The arm 17 is
pivotally
connected at one end 24 to a top end of the boom 16 and at an opposed end 25
to an
end of the connector flange 18. A bucket control cylinder 26 is connected to
the
connector flange 18 to displace the bucket 19. A hydraulic cylinder 27
displaces the
arm 17.
With reference now to Figure 5, there is shown generally at 30 a
hydraulic shovel lifting jig. The jig 30 is comprised of a body member 31
normally
casted in steel having a jig fixation hole 32 in a lower section thereof
herein in a
depending arm 33 for securement to the existing pivot attachment 23 where the
lower
end 22 of the boom cylinder 21 is connected. In order to do so, it is
necessary to
disconnect the boom cylinder lower end 22 from the pivot attachment 23. As
shown
in Figure 3, the lifting jig 30 is secured to the hydraulic shovel 10 with the
front
attachments 15 having been removed. As will be seen hereinafter, the lifting
jig 30
provides a means to lift the shovel or the front end of the superstructure 11
from the
truck 12 for servicing.
The hydraulic shovel lifting jig 30 also has a lug 34 secured at an
upper end thereof and provided with a hole 35 whereby to receive and connect
therein
the lower end 22 of the boom cylinder 21 which has been disconnected from its
pivot
attachment 23. The lower end 22 of the boom cylinder is mounted for pivotal
movement in hole 35. The body member 31 is further provided with a lifting
force
application surface, which may take the form of a horizontal downward-facing
surface
formation 36 projecting forwardly of the jig fixation hole 32 and under the
lug 34 at a
predetermined distance from the jig fixation hole 32 and the hole 35 of the
lug 34 for
receiving thereunder an upward lifting force from suitable lifting devices,
such as
hydraulic jacks, etc. The body member 31 further has a thrust surface 37
formed at a
specific angle in relation to an associated abutment surface 38 of the
superstructure
frame 39 whereby to transfer the load from the horizontal surface formation 36
to the
superstructure 11 during lifting. As can be appreciated from Fig. 5, the
thrust surface
37 may include a replaceable wear pad.
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With additional reference to Figures 2 to 4, there is shown the lifting
jig 30 secured in position at the front end of the superstructure 11 and
engaged with
the boom cylinder 21, which has been fully retracted. The arm cylinder 27 is
also
shown in a fully retracted position. Accordingly, the boom 16 and the arm 17
are in
the fully retracted position with the retracted cylinders acting as rigid
supports and
preventing further displacements of the boom 16 and the arm 17 in the unlikely
event
of a loss in hydraulic pressure. Accordingly, the front attachments 15 are
safely
secured. The thrust surface 37 is maintained in uniform bearing contact with
the
associated bearing surface of the superstructure 11 for the full range of
motion of the
boom 16 and the arm 17. It can be appreciated from Fig. 2 that the axis of the
boom
cylinder 21 extends to the right of the bottom pivot attachment 23, thereby
providing
a lever arm to bias the pivotable lifting jig 30 in a clockwise direction with
the thrust
surface 37 thereof in uniform bearing contact with the corresponding arresting
surface
of the superstructure 11. The position of the hole 35 relative to the jig
fixation hole 32
is selected to ensure that the axis of the boom cylinder 21 is such that the
thrust
surface 37 is urged in uniform bearing contact against the superstructure 11
at all
time, thereby preventing the lifting jig from pivoting forwardly in a counter
clockwise
direction, which pivotal movement would cause the boom and the arm to abruptly
fall
on the ground. The distance between the jig fixation hole 32 and the hole 35
in the lug
34 is selected so that when the boom cylinder 21 and the arm cylinder 27 are
fully
retracted (Fig. 2), the bucket is held at an appropriate distance above the
ground with
the arm 17 depending vertically from the boom 16. If the distance between the
holes
32, 35 is not sufficient, the boom and arm cylinders 21, 27 would have to be
at least
partly extended to hold the bucket above the ground. It is obviously not
suitable to
rely on hydraulic pressure to maintain the boom and arm in position when the
shovel
is not being used. It may also pose major safety concerns during lifting for
instance in
the event of a malfunction of the hydraulic system of the shovel. Also it is
desirable
for the arm 17 to be vertical during the lifting operation in order not to
create any
unbalance. The geometry of the lifting jig must thus be designed in accordance
with
the geometry of the boom and the arm of the hydraulic shovel.
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It is pointed out that when the lifting jig 30 is secured to the hydraulic
shovel 10, as above described, it fulfills three main functions. Firstly, it
creates a
horizontal plane, the surface 36 in front of the superstructure 11 of the
shovel, to
allow a lifting device, such as a jack (not shown), to exert the required
upward force,
as indicated by arrow 28 in Figure 4 that will actually lift the front of the
shovel once
transmitted to the superstructure through the lifting jig 30. Other jacks are
secured
under the superstructure, such as indicated by arrow 29 in Figure 4 to lift
the
superstructure from the truck 12 to permit the truck from being removed from
under
the superstructure to provide maintenance to the rolling circle mechanism 14
or other
otherwise none accessible parts of the shovel.
A second main function of the lifting jig 30 is that it provides
attachments for the boom cylinder lower end in a predetermined location that
fulfills
two necessary goals. One goal is never to rely on the hydraulics secured to
the
cylinders for safety reasons by allowing boom and arm cylinders to be fully
retracted
while front attachments are kept in the desired position for the lift, and
secondly to
prevent the bucket 19 from ever touching the ground and result in dangerous
shifting
of the shovel load while the shovel is supported by the lifting device.
The third main function of the lifting jig 30 is that it permits the use of
the hydraulics to actuate the front attachments 15 when needed prior to or
after the
lift.
Summarizing, one embodiment of the lifting jig has four main
characteristics:
1. One hole at its bottom that will allow pivotally mounting the jig
to the shovel where the boom cylinders are normally pinned (i.e. the jig is
pinned to
an existing point of attachment, no need for welding or the like).
2. Lugs at its top to allow attaching a boom cylinder's lower end.
3. A nose with a downwardly facing horizontal surface where the
lifting device will apply its upward force.
4. A thrusting surface at its back that will transfer the lifting
device's force to the shovel.
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The lifting jig geometry can be designed to fit any hydraulic shovel
make or model. The capacity of the jig is designed to withstand, with adequate
safety
factors, all forces involved in preparation, during or after a lift and this
for any lifting
scenario such as but not limited to:
1. The jig is supporting only the load of the front attachments
(before or after the actual lift).
2. The shovel is lifted through the use of the jig while the jig is
supporting the load of the front attachments (i.e. Boom-On Lift).
3. The shovel is lifted through the use of the jig while front
attachments have been removed (i.e. Boom-Off Lift).
The design considers also uneven loading conditions such as but not
limited to when all the weight of the shovel is supported by only one lifting
jig.
In the drawings only one of the hydraulic shovel lifting jigs 30 is
illustrated but it is understood that most of these hydraulic shovels have
boom
cylinders and arm cylinders disposed on the opposed sides of the boom and arm
and
therefore a lifting jig is provided on an opposed side of the boom and
connected to
respective one of the boom hydraulic cylinders 21.
The method of safely lifting a superstructure of a hydraulic shovel
above a truck thereof while the front attachments are secured to the
superstructure
will now be described. The method comprises the steps of disconnecting a lower
end
of one or two boom cylinders of the front attachments from a respective pivot
attachment secured to the superstructure. The lifting jig 30 of the present
invention
has a jig fixation hole for securement to the pivot attachments by the boom
cylinders.
The lower end of the boom cylinders are then secured to a lug of the lifting
jig spaced
above the pivot attachments. The lifting jig also has a transfer surface to
transfer the
load from the front attachment to the superstructure through a thrust surface
of the
lifting jig. A lifting thrust is applied to the front horizontal surface of
the lifting jig
with the one or two boom cylinders and arm cylinders of the front attachments
fully
retracted. The lifting thrust applied to the lifting jig is synchronized with
other lifting
thrusts applied to the superstructure. Accordingly, the superstructure with
its front
attachments secured thereto can be lifted above the truck to provide servicing
or
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repair of otherwise none accessible parts while maintaining the front
attachments
engaged and providing the advantages as herein mentioned. The method also
comprises using the lifting jig 30 with the front attachments 15 removed to
provide a
support for thrust devices, such as jacks to lift the superstructure from the
truck or
both lift the superstructure and the truck as a unit for servicing.
It is within the ambient of the present invention to cover any obvious
modifications provided such modifications fall within the scope of the
appended
claims.
