Note: Descriptions are shown in the official language in which they were submitted.
APPARATUS AND METHOD FOR LIFTING HEAVY MACHINERY
TECHNICAL FIELD
The application relates generally to raising heavy equipment and, more
particularly, to a
method and apparatus for synchronizing the lifting of heavy machinery.
BACKGROUND OF THE ART
Routine maintenance often requires that heavy equipment such as mechanical
shovels, excavators, and transport trucks be raised in elevation. This allows
maintenance crews to access the lower components of the heavy equipment so as
to
perform maintenance and repairs, and saves time and effort by avoiding having
to
dismantle the heavy equipment.
Consider the example of a large mechanical or electrical shovel having a lower
carbody or tractor which uses continuous track motion to displace the shovel.
In order
to repair or replace the sideframe of the carbody, its treads, or the rollers
which turn the
treads, it would be desirable to access these components without having to
first
separate them from the carbody. This can be done by raising the carbody.
Conventional techniques for raising the carbody for maintenance work use high
capacity jacks positioned under the carbody in select locations. Raising the
entire
carbody (and thus the shovel) in this way is certainly possible, but poses
safety risks.
The carbody is relatively compact in comparison to the shovel itself, and
raising just the
carbody can affect the lateral and longitudinal stability of the shovel. It
may therefore
be necessary to compensate for instability issues.
Furthermore, raising the carbody of such a shovel requires special attention.
At no time
should tension be applied on the center gudgeon or center nut connecting the
carbody
to the upper works of the shovel. If tension were to be applied, there is a
risk of partial
extraction and/or damage being caused to these components, which would result
in
lengthy and/or costly repairs and lead to significant productivity losses due
to shovel
inactivity.
To avoid these potential hazards, some conventional techniques raise only one
part of
the shovel at a time, and perform the maintenance work on only that part. This
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lengthens considerably the time budgeted for maintenance, and causes
significant
productivity losses due to shovel inactivity.
SUMMARY
There is described herein an apparatus and method for lifting heavy machinery
from a
ground surface. Vertically extendable first lifting devices engage an upper
portion of the
machinery and displace the upper portion upward. Vertically extending second
lifting
devices engage a lower portion of the machinery and extend to collectively
apply a
constant force simultaneously with the upward displacement of the upper
portion. A
controller sends lift signals to vertically extend the respective lifting
devices, and also
sends hold signals to maintain the first lifting devices extended and to
continue applying
the constant force with the second lifting devices.
In one aspect, there is provided a method for lifting heavy machinery from a
ground
surface, the heavy machinery having an upper portion and a lower portion. The
method
comprises positioning the upper portion to engage a plurality of vertically
extendable
first lifting devices, and positioning the lower portion to engage a plurality
of vertically
extendable second lifting devices; lifting the upper and lower portions from
the ground
surface by vertically extending the first lifting devices; supporting a weight
of the lower
portion while lifting the upper and lower portions by vertically extending the
second
lifting devices; and holding the first lifting devices in an extended position
and applying
a constant lifting force to the lower portion with the second lifting devices.
In still another aspect, there is provided a method for lifting heavy
machinery from a
ground surface, the heavy machinery having an upper portion and a lower
portion. The
method comprises: positioning the upper portion above a plurality of
vertically extendable
first lifting devices, and positioning the lower portion above a plurality of
vertically
extendable second lifting devices; engaging the plurality of vertically
extendable second
lifting devices with the lower portion; lifting the upper and lower portions
from the ground
surface by vertically extending the first lifting devices while simultaneously
supporting a
weight of the lower portion with the second lifting devices by vertically
extending same;
and holding the first lifting devices in an extended position and
simultaneously supporting
the weight of the lower portion with the second lifting devices. In an
embodiment,
simultaneously supporting the weight of the lower portion with the second
lifting devices
while holding the first lifting devices in the extended position comprises
applying a
constant lifting force to the lower portion with the second lifting devices.
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In another aspect, there is provided an apparatus for lifting heavy machinery
from a
ground surface, the heavy machinery having an upper portion and a lower
portion. The
apparatus comprises first lifting devices engageable with the upper portion
and
vertically extendable to displace the upper portion upward from the ground
surface;
second lifting devices engageable with the lower portion and vertically
extendable to
support the lower portion simultaneously with an upward displacement of the
upper
portion and to collectively apply a constant force to the lower portion when
the first
lifting devices are held in an extended position; and a controller operatively
coupled to
the first lifting devices and the second lifting devices. The controller is
configured for
providing command signals thereto for vertically extending the first lifting
devices to lift
the upper and lower portions from the ground surface; vertically extending the
second
lifting devices to support a weight of the lower portion while lifting the
upper and lower
portions; and holding the first lifting devices in the extended position while
applying the
constant lifting force to the lower portion with the second lifting devices.
In a further aspect, there is provided a computer readable medium having
stored
thereon program code executable by a processor for lifting heavy machinery
from a
ground surface using first lifting devices engageable with an upper portion of
the heavy
machinery and second lifting devices engageable with a lower portion of the
heavy
machinery. The program code comprises instructions for vertically extending
the first
lifting devices to lift the upper portion and lower portion from the ground
surface;
vertically extending the second lifting devices to support a weight of the
lower portion
while lifting the upper portion and the lower portion; and holding the first
lifting devices
in an extended position while applying a constant lifting force to the lower
portion with
the second lifting devices.
DESCRIPTION OF THE DRAWINGS
Reference is now made to the accompanying figures in which:
Fig. la is a rear view of an apparatus for lifting heavy machinery having an
upper
portion and a lower portion, according to an embodiment of the present
disclosure.
Fig. lb is another rear view of the apparatus of Fig. la showing first lifting
devices and
second lifting devices of the apparatus in a vertically extended position.
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Fig. 2a is an exemplary embodiment of the controller of the lifting apparatus,
embodied
on a computer;
Fig. 2b is an exemplary embodiment of the controller of the lifting apparatus,
embodied
in a PLC;
Fig. 3 is a top view of the lifting apparatus without the heavy machinery;
and
Fig. 4 is a flow diagram showing a method for lifting heavy machinery from a
ground
surface, according to another embodiment of the present disclosure.
DETAILED DESCRIPTION
There is described herein an apparatus used to lift or raise heavy machinery.
The
apparatus coordinates the lifting of the heavy machinery so that it can be
raised with
respect to a ground surface. In so doing, the apparatus provides clearance so
that
vehicles and maintenance crews can access the lower ends of the heavy
machinery,
and suspends the heavy machinery at an elevation while the maintenance
operation is
being performed.
The heavy machinery can be any type of heavy equipment such as mechanical or
electrical shovels, excavators, transport trucks, bulldozers, or other similar
devices.
The heavy machinery discussed herein includes both immobile equipment and
vehicles
which can be displaced using their own source of motive power. Irrespective of
the
type of equipment used, the heavy machinery is characterised by an upper
portion and
a lower portion.
Figures la and lb illustrate an exemplary heavy machinery 50, such as a
massive
mechanical or electrical shovel. An upper portion 52 sits on a lower portion
54 on a
ground surface 12. The heavy machinery 50 is provided on a lifting apparatus
10.
Figure la illustrates the apparatus 10 in an initial position, before
extension thereof and
lifting of the heavy machinery 50.
The lower portion 54 or lower works of the shovel may comprise a carbody 55
which
helps to displace the shovel to different digging areas. The carbody 55 may
include a
sideframe 56 on each of its sides. Each sideframe 56 contains rollers 57 which
turn a
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tread 58 allowing the shovel to be moved. The upper portion 52 or upper works
of the
shovel may include a cabin which is detachably mounted onto the carbody 55 and
rotatable relative to the carbody 55. An operator may sit inside the cabin to
control the
operation of the shovel. The upper portion 52 can also include a boom (not
shown)
attached to the cabin and attached to the digger for excavating materials.
The apparatus 10 comprises first lifting devices 20 for lifting the heavy
machinery 50,
second lifting devices 30 for supporting the weight of the lower portion 54 of
the
machinery 50 as it is being lifted, and a controller 40 for coordinating the
lifting
operation and the extension of one or more of the first and second lifting
devices 20,30.
In some embodiments, the apparatus 10 is a combination of first lifting
devices 20 and
a first controller and second lifting devices 30 that are coupled to the first
lifting devices
and have their own corresponding second controller. The second lifting devices
30
may be connected to the first lifting devices 20 in a master-slave
configuration, and the
second controller may be an add-on to the first controller, together forming
controller
15 40. For example, the first controller may comprise control logic to
selectively extend
and contract the first lifting devices. The second controller may be connected
into a
control panel of the first controller to add control logic to synchronize
extension and
contraction of the second lifting devices 30 with the first lifting devices
20, and to apply
a constant force via the second lifting devices 30 while the first lifting
devices are
20 extended. Alternatively, a single controller 40 may be conceived to
control both first
lifting devices 20 and second lifting devices 30.
The plurality of first lifting devices 20 are responsible for applying a
lifting force to
displace both the upper portion 52 and the lower portion 54 attached thereto
vertically
upward. In so doing, the first lifting devices 20 lift the entirety of the
heavy machinery 50
.. from the ground surface 12. Each first lifting device 20 can therefore take
any form or
configuration capable of such functionality, such as hydraulic jacks,
mechanical jacks,
house jacks, farm jacks, pneumatic jacks, and strand jacks. The first lifting
devices 20
may also comprise lifting kits.
Figure lb illustrates the apparatus 10 in an extended position. The first
lifting devices 20
may comprise a housing 22 and a shaft 24. The housing 22 forms the corpus of
the first
lifting device 20 and provides structure thereto. The housing 22 can take many
forms.
For example, the housing 22 can include a base plate which is placed against
the
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ground surface 12 and helps to spread the load supported by the first lifting
device 20
over a greater surface area. The housing 22 may also have a jack stand
projecting from
the base plate to house the vertically displaceable shaft 24. The jack stand
can be
structurally supported by gusset plates mounted to both the jack stand and the
base
plate.
The shaft 24 contained within the housing 22 extends vertically out of the
housing 22.
When it extends, the shaft 24 applies the lifting force to the upper portion
52 and causes
its upward displacement. In the example illustrated, the shaft 24 extends
vertically out of
a bottom of the housing 22, such that the lifting force is applied downward.
It is
therefore the reactive force of the ground surface 12 which causes the upward
displacement of the upper portion 52. It will be appreciated that shafts 24
which extend
out of the top of the housing 22 are also within the scope of the present
disclosure. The
output end of the shaft 24 (i.e. the end which extends out of the housing 22)
can be
provided with an application plate or other similar device to distribute the
lifting force.
In operation, the first lifting devices 20 engage the upper portion 52 in
order to apply the
lifting force to displace the upper portion 52 upward with respect to the
ground surface
12. Each shaft 24 extends away from the housing 22 a predetermined length. The
predetermined length corresponds to the height to which it is desired to lift
the lower
portion 54 and/or the shovel 50. It is generally determined prior to
commencing the
lifting operation, and may be the only input provided to the first lifting
devices 20. For
example, an operator of the apparatus 10 may input a predetermined length of
12
inches into the controller 40 for each of the first lifting devices 20, this
predetermined
length being the distance by which the entire shovel 50 should be lifted. The
shaft 24 of
each of the first lifting devices 20 will therefore have instructions to
vertically extend as
much as is required to raise the heavy machinery 12 inches.
The predetermined length can be monitored using any appropriate sensor, such
as a
distance sensor 26 mounted to one or more of the first lifting devices 20. The
distance
sensors 26 monitor the vertical extension of the shafts 24 with the respect to
the ground
surface 12. This can prove to be useful information because the ground surface
12 may
not be at the same level for all of the first lifting devices 20, or may have
shifted during
the lifting operation. The operator of the apparatus 10 may therefore wish to
know what
is the displacement of each first lifting device 20 relative to the ground
surface 12 at any
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given moment. The shafts 24 of some first lifting devices 20 may consequently
need to
extend more or less in order to achieve the predetermined length.
The distance sensor 26 may measure the distance that it, or the part of the
first lifting
device 20 to which it is attached, has risen with respect to the ground
surface 12. The
distance sensor 26 can employ a laser or radio signals, to name but a few
techniques,
to achieve such functionality. Prior to the lifting operation, the distance
sensors 26 may
each set an initial reference point, or zero point, on the ground surface 12
which
corresponds to the initial height of the distance sensor 26 from the ground
surface 12.
The predetermined length is then measured as the distance that the distance
sensor 26
has moved relative to this initial reference point, which also corresponds to
the vertical
extension of the corresponding shaft 24. The lifting operation ceases when the
first
lifting devices 20 have each achieved the predetermined length. The distance
sensors
26 may communicate with the controller 40 so that it can track the progress of
the first
lifting devices 20.
It will thus be appreciated that the first lifting devices 20 may be
actuators. In some
embodiments, each first lifting device 20 acts generally as one or more
hydraulic
actuator, such as a single-acting hydraulic actuator having a counterbalance
valve. The
counterbalance valves, or holding valves, offer a higher level of hydraulic
safety
protection. The counterbalance valves may automatically shut off in case of a
hydraulic
leak and ensure that oil remains trapped inside the hydraulic actuators, thus
safely
supporting the load while the leak gets fixed. It will be appreciated that the
first lifting
devices 20 can be other types of actuators as well (e.g. mechanical,
electrical, or
pneumatic), or combinations of different types of actuators. For example, each
of the
first lifting devices 20 may include two hydraulic actuators. It will also be
understood that
the first lifting devices 20 can be other types of lifting devices (e.g.
cranes, hoists,
elevators, etc.), depending on various factors such as but not limited to the
loads to be
supported, the space available for the lifting operation, the geometry of the
heavy
machinery, and the desired level of safety.
The apparatus 10 also includes second lifting devices 30, which collectively
apply a
constant force by vertically extending, thereby supporting at least the weight
of the
lower portion 54 while the first lifting devices 20 are displacing the upper
portion 52. In
so doing, the second lifting devices 30 ensure that the heavy machinery 50
does not
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experience tension during the lifting operation, and that the lower portion 54
does not
pull or cause a tension to be applied to the upper portion 52.
The first lifting devices 20 and second lifting devices 30 may thus operate
(or extend)
simultaneously or substantially simultaneously. The term "simultaneously"
refers to the
.. coordination of the movement of the second lifting devices 30 with that of
the first lifting
devices 20. More particularly, the first and second lifting devices 20,30 may
have a
"master-slave" relationship, in that the second lifting devices 30 will only
vertically
extend if the first lifting devices 20 are also vertically extending. Stated
differently, if the
shafts 24 of the first lifting devices 20 stop vertically extending, so too
will the second
lifting devices 30. Even when not vertically extending, the second lifting
devices 30
continue to apply the constant force to ensure that the lower portion 54 is
continually
supported.
Each of the second lifting devices 30 may have a lower housing 32 and a lower
shaft
34. The lower housing 32 and lower shaft 34 of each second lifting device 30
may be
similar to the housing 22 and shaft 24 of each first lifting device 20. The
description
given above for these components of the first lifting device 20 therefore
applies mutatis
mutandis to the lower housing 32 and the lower shaft 34. In some embodiments,
the
stroke of the shaft 24 of the first lifting devices 20 will be greater than
the stroke of the
lower shaft 34 of the second lifting devices 30. This is reflective of the
role of the first
lifting devices 20, which is to displace the shovel 50 upwards. In contrast,
the second
lifting devices 30 are intended in most instances to support at least the
weight of the
lower portion 54 while it is being lifted upward by the first lifting devices
20.
In operation, each second lifting device 30 engages, or is engageable with,
the lower
portion 54, in the same ways as described above for the first lifting devices
20 with
respect to the upper portion 52. The second lifting devices 30 are disposed
within a
perimeter defined by the position of the first lifting devices 20. In Figs. la
and lb, each
of the second lifting devices 30 are shown disposed directly underneath a
lower surface
of the lower portion 54 so that the output ends of the lower shafts 34 can
abut directly
against this lower surface in order to apply the constant force. It will be
appreciated,
however, that the second lifting devices 30 can be arranged differently than
as shown,
provided that they collectively apply the constant force to the lower portion
54.
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When being used to support the lower portion 54, each of the lower shafts 34
extends
away from their lower housings 32 in synchronization with the upward
displacement of
the upper portion 52 by the first lifting devices 20. Stated differently, the
second lifting
devices 30, and thus their lower shafts 34, are not vertically extending if
the shafts 24 of
the first lifting devices 20 are inactive. If desired, shims 31 can be placed
in the space
between the output end of one or more lower shafts 34 and the lower portion 54
to
further reduce the distance that the lower shafts 34 need to vertically
extend. One or
more mechanical locks 36 may be mounted about the vertically extended lower
shafts
34 to help them support the lower portion 54. Once tightened about the
exterior surface
.. of the lower shafts 34, each mechanical lock 36 may hold the lower shaft 34
solidly in
place after the required extension has been reached. The load will therefore
be
supported structurally as well as hydraulically, thus allowing for safe access
under the
lower portion 54 during maintenance work.
The second lifting devices 30 collectively apply the constant force to the
lower portion
.. 54. The constant force may remain constant throughout and after the lifting
operation.
The term "collectively" when used to describe the application of the constant
force
refers to a constant force value which is the sum of forces applied by all of
the second
lifting devices 30. For example, an operator of the apparatus 10 can input a
constant
force value of about 500 tons into the controller 40, which will control the
vertical
extension of the lower shafts 34 such that their combined force output is 500
tons. This
force output will remain constant throughout the lifting operation, and is
also applied
after the lifting operation has ceased in order to support at least the weight
of the lower
portion 54. Such a constant force value is generally determined prior to
commencing
the lifting operation, and may be the only input provided to the second
lifting devices
30. The collective application of the constant force is in contrast with the
operation of
the first lifting devices 20, whose sole input is generally the predetermined
length. Each
of the first lifting devices 20 may apply a varying lifting force in order to
achieve the
predetermined length, and to compensate for any instabilities which may arise
during
the lifting operation.
The number of second lifting devices 30 which apply the collective constant
force, and
their position with respect to the lower portion 54, can vary. For example,
the apparatus
10 can include four second lifting devices 30. Two of the four second lifting
devices 30
may be disposed towards a front of the lower portion 54 and directly
underneath, while
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the other two may be disposed underneath and towards a rear. Such a
disposition of
the second lifting devices 30 provides stability to the lifting operation, and
helps to
distribute the constant force. It will be appreciated that more or fewer
second lifting
devices 30 can also be used. For example, three second lifting devices 30 may
be
positioned underneath the lower portion 54 in a triangular configuration and
spaced
1200 from one another.
The constant force can be distributed to the second lifting devices 30 in
different ways.
For example, an operator may select a constant force value of about 500 tons.
The
controller 40 may divide this constant force value equally amongst the number
of
second lifting devices 30. Therefore, in an embodiment where the apparatus 10
has
four second lifting devices 30, each one may apply a fractioned constant force
value of
125 tons. The controller 40 and/or operator may also divide the constant force
value
unequally. In an embodiment where the apparatus 10 has four second lifting
devices
30, three of them can apply a fractioned constant force value of 150 tons
each, while
the last one can apply 50 tons. This unequal distribution of the constant
force value is
particularly useful when the operator wants to verify if all of the second
lifting devices
30 are operational. In some embodiments, the forces are distributed amongst
the
second lifting devices 30 as a function of a configuration thereof. For
example, in a
square configuration, the forces may be applied equally. Alternatively, the
second lifting
devices 30 may be positioned with a pair of second lifting devices 30 on one
side and
an individual second lifting device 30 on another side. The forces may be
distributed so
that half of the total force is applied to the individual second lifting
device 30 and the
other half is split between the pair of second lifting devices 30. Other
configurations for
the second lifting devices 30 and/or the distribution of forces, will be
readily
understood.
The actual value of the constant force may be calculated in different ways. In
some
embodiments, the constant force value may be set such that it is greater than
the
weight of the lower portion 54 of the heavy machinery, but still less than the
overall
weight of the heavy machinery. For example, if the lower portion 54 weighs
about 470
tons and the heavy machinery as a whole weighs about 1,500 tons, the constant
force
value may be set to 500 tons. This allows the second lifting devices 30 to
support the
weight of the lower portion 54 as it is raised and after the lifting operation
has ceased,
while not necessarily being able to lift the entire heavy machinery. It is
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CA 2980365 2018-11-21
easier to lower the lower shafts 34 when the heavy machinery is brought back
to the
ground surface 12. As a general rule, the constant force value may be
calculated to be
at least the weight of the lower portion 54, multiplied by a safety factor.
Some possible
safety factors range between about 1.10 to about 1.30, but other safety
factors are also
within the scope of the present disclosure.
It will be appreciated that the unit of constant force outputted by each of
the first and
second lifting devices 20,30 can include tons/tonnes, psi/Pa, lbs/N depending
on the
type of lifting device 20,30. Indeed, and as with the first lifting devices
20, each of the
second lifting devices 30 may be an actuator. In some embodiments, each second
lifting device 30 is a hydraulic actuator, such as a double-acting hydraulic
actuator
having a lower counterbalance valve similar to the one described above. It
will be
appreciated that the second lifting devices 30 can be other types of actuators
as well
(e.g. mechanical, electrical, or pneumatic), or combinations of different
types of
actuators, as well as other types of lifting devices as well (e.g. cranes,
hoists,
elevators, etc.).
The apparatus 10 also comprises a controller 40, which communicates commands
to
one or more of the components of the apparatus 10 and may also receive
feedback
therefrom. More particularly, the controller 40 communicates with one or more
of the
first lifting devices 20 and the second lifting devices 30. The controller 40
sends lift
signals 44 to both the first and second lifting devices 20,30 to command them
to
vertically extend the shafts 24 and lower shafts 34, respectively, and effect
the lifting
operation.
The controller 40 also sends hold signals 42 to command the first lifting
devices 20
and/or their shafts 24 to cease displacing the upper portion 52, and thus,
cease lifting
.. the heavy machinery 50 as a whole. The length at which the shafts 24 are
stopped is
their extension length, which may or may not correspond to the predetermined
length.
The hold signals 42 may also be sent to the second lifting devices 30 to
command them
to continue applying the constant lifting force. The controller 40 sends the
hold signals
42 when either one of the two following conditions occur: one of the second
lifting
devices 30 has reached a vertical extension limit, and the first lifting
devices 20 are
vertically extended to the predetermined length. The first condition is an
added safety
measure, and builds redundancy into the apparatus 10. The vertical extension
limit is
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the maximum distance that the lower shafts 34 of the second lifting devices 30
can
extend to before they are no longer able to abut against the lower portion 54
to apply
the constant force. When one of the second lifting devices 30 reaches this
distance, it is
no longer contributing to the collective application of the constant force.
While the other
second lifting devices 30 can generally compensate for the loss of force
output from one
or more of the second lifting devices 30, it may be desired to instead stop
the lifting
operation altogether out of an abundance of caution. Therefore, the first of
the second
lifting devices 30 which is close to and/or risks exceeding its vertical
extension limit may
signal the controller 40, and the first lifting devices 20 will cease applying
the lifting force
to thereby stop the lifting operation. This ensures that all of the second
lifting devices 30
are applying the constant force to support the lower portion 54. The vertical
extension
limit may or may not correspond to the maximum stroke of each of the lower
shafts 34,
and can also vary for each second lifting device 30.
The second condition involves the first lifting devices 20 reaching the
predetermined
length, which as explained above, corresponds to the height to which the heavy
machinery 50 is lifted. Once the shafts 24 have each extended to the
predetermined
length, the lifting operation has been achieved and it is no longer necessary
to continue
lifting. In such a case, the extension length of each shaft corresponds to the
predetermined length. The shafts 24 may therefore signal the controller 40
that the
desired height has been achieved, and the controller 40 may respond with the
hold
signals 42 instructing the shafts 24 to cease vertically extending.
It will be appreciated that the controller 40 can send other signals as well.
For example,
the controller 40 can send a constant force input signal to all of the second
lifting
devices 30 actuating their lower shafts 34 to exert a specific constant force
value.
Similarly, the controller 40 can send a predetermined length input signal to
each of the
first lifting devices 30, actuating their shafts 24 to exert the lifting force
required to
extend to the predetermined length. Other such signals are also within the
scope of the
present disclosure.
The controller 40 can take many different physical forms. Figure 2a is an
exemplary
embodiment of the controller 40, which may comprise, amongst other things, a
plurality
of applications 206a. ..206n running on a processor 204 coupled to a memory
202. One
such application may be configured for lifting the upper portion 52 of the
heavy
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machinery. Another application may be configured for applying the constant
force to the
lower portion 54 of the heavy machinery. In some embodiments, a single
application
may be provided for lifting the upper portion 52 and applying the constant
force to the
lower portion 54. It should be understood that while the applications 206a ...
206n
presented herein are illustrated and described as separate entities, they may
be
combined or separated in a variety of ways.
The memory 202 accessible by the processor 204 may receive and store data,
such as
but not limited to extension lengths of the first lifting devices 20,
extension lengths of the
second lifting devices, forces to be applied, and force distribution among
lifting devices.
The memory 202 may be a main memory, such as a high speed Random Access
Memory (RAM), or an auxiliary storage unit, such as a hard disk, a floppy
disk, or a
magnetic tape drive. The memory 202 may be any other type of memory, such as a
Read-Only Memory (ROM), flash memory, or optical storage media such as a
videodisc
and a compact disc. The processor 204 may access the memory 202 to retrieve
data.
The processor 204 may be any device that can perform operations on data.
Examples
are a central processing unit (CPU), a front-end processor, a microprocessor,
and a
network processor. The applications 206a ... 206n are coupled to the processor
804
and configured to perform various tasks.
In an alternative embodiment, the controller 40 may comprise an industrial
control
system, such as a distributed control system (DCS) or a programmable logic
controller
(PLC). An example is illustrated in figure 2b, where the controller 40
comprises an
operator interface 208, a memory 202, a control unit 210, and an arithmetic-
logic unit
(ALU) 212. PLC programs may be downloaded onto the memory 202 via an input
port
(not shown) such as Ethernet, RS-232, RS-485, or RS-422. In some embodiments,
the
PLC programs may also be provided through a programming board which writes the
program into a memory 202 in the form of a removable chip such as an
Electrically
Erasable Programmable Read-Only Memory (EEPROM) or an Erasable Programmable
Read-Only Memory (EPROM). The control unit 210 selects and calls up
instructions
from the memory 202 in appropriate sequence and relays the proper commands.
Other
embodiments are also feasible for the controller 40, such as Programmable
Logic
Relays (PLR), electronic boards with microcontrollers, and other such devices.
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In some embodiments, the controller 40 comprises one or more control panels,
each
having its own PLC. For example, a first control panel may communicate with,
and
receive feedback from, the first lifting devices 20. A second control panel
may also be in
communication with the first control panel to receive commands based on the
movement of the first lifting devices 20. The second control panel can also
communicate with, and receive feedback from, the second lifting devices 30, so
that
they move in synchronicity with the first lifting devices 20. An operator can
input
variables into one or more of the control panels via the operator interface
208. These
input values can be, for example, the constant force to apply with the second
lifting
devices 30, and/or the predetermined length of the first lifting devices 20.
In some
embodiments, the operator may manually select one of the first lifting devices
20 and/or
one of the second lifting devices 30 and input a predetermined height or a
force,
respectively, to be applied. The inputs may be provided as any integer value
or selected
from a list or a drop-down menu. Appropriate hydraulic and electronic cabling
can
extend to and from the lifters 20,30 and the control panels. Alternatively,
the controller
40 may communicate with the apparatus 10 wirelessly, via any sort of network
such as
the Internet, a cellular network, Wi-Fi, or others known to those skilled in
the art.
In some embodiments, the controller 40 is configured to be accessible from any
one of
a plurality of devices, such as a laptop computer, a personal digital
assistant (PDA), a
smartphone, or the like, adapted to communicate over the network.
Alternatively, the
controller 40 may be provided in part or in its entirety directly on the
devices, as a native
application or a web application. It should be understood that cloud computing
may also
be used such that the controller 40 is provided partially or entirely in the
cloud. In some
embodiments, an application 206a may be downloaded directly onto a device and
application 206n communicates with application 206a via the network.
The apparatus 10 may be operated as follows. Prior to setting up the apparatus
10,
the ground surface 12 can be compacted to further improve its solidity and
provide
adequate bearing pressure. At least some of the first lifting devices 20 and
the second
lifting devices 30 are put into position. Furthermore, one or more layers of
raised
support racks can be laid on the ground surface 12. The support racks provide
an
easy and inexpensive way to raise the heavy machinery 50 an initial amount
(e.g. 12
in., or integer multiples thereof) by simply driving the lower portion 54 over
the support
racks and bringing it to rest thereon. The upper and lower portions 52,54 are
therefore
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positioned over, or near, the first lifting devices 20 and the second lifting
devices 30
that are already in position.
The remaining first lifting devices 20 and/or second lifting devices 30 can
now be put
into place so that they are positioned to effect the lifting operation and
support the
lower portion 54, respectively. The operator can determine the height to lift
the heavy
machinery depending on the maintenance to be performed, and input it into the
controller 40 (e.g. 12 in.). In some embodiments, any integer value may be
input into
the controller 40. Alternatively, the operator may choose from a set of
predetermined
values, such as 10 inches, 20 inches, and 30 inches.
In some embodiments, shims 31 may be placed between the output end of the
lower
shafts 34 and the lower portion 54. If the weight of the lower portion 54 and
the upper
portion 52 are known, the operator can determine the desired constant force to
be
collectively applied by the second lifting devices 30, and input the constant
force value
into the controller 40 (e.g. 500 tons). Alternatively, the weight may be input
into the
controller 40 and the constant force may be determined by the controller 40 as
a
function of the weight and the height to which the heavy machinery is to be
lifted.
The controller 40 may send lift signals 44 to the first lifting devices 20 to
command them
to vertically extend their shafts 24. The controller 40 may simultaneously
send lift
signals 44 to the second lifting devices 30 so that they support the weight of
the lower
portion 54 while the shafts 24 of the first lifting devices 20 are vertically
extending.
Alternatively, the first lifting devices 20 and the second lifting devices 30
are operatively
connected together such that when the first lifting devices 20 receive lift
signals 44 from
the controller 40, they in turn instruct the second lifting devices 30 to
support the weight
of the lower portion 54.
The apparatus 10 therefore allows for a useful division of labour between the
lifting
devices 20,30. More particularly, first lifting devices 20 are allowed to
concentrate on
the lifting operation and to counteract any systemic lateral instabilities
(e.g. wind,
ground shake, proximity mine blasts, sudden ground bearing capacity failure,
etc.), thus
balancing the heavy machinery 50 against perturbations. The second lifting
devices 30
are meanwhile allowed to focus only on supporting the lower portion 54 so as
to
eliminate any tension acting thereon.
CA 2980365 2018-11-21
The shafts 24 and lower shafts 34 continue to vertically extend, and the
second lifting
devices 30 apply the constant force, until the predetermined length of 12 in.
has been
achieved with each of the first lifting devices 20, or until the lower shaft
34 of one of the
second lifting devices 30 has reached its vertical extension limit. Once
either one of
these situations occur, one or more of the lifting devices 20,30 signals the
controller 40.
The controller 40 responds by sending the hold signals 42 to the first lifting
devices 20
to maintain their vertical extension, and to the second lifting devices 30 to
continue
applying the constant force of 500 tons. In some embodiments, the lower shafts
34 of
the second lifting devices 30 can be braced with the mechanical locks 36. The
shovel
50 is now raised with respect to the ground surface 12, as shown in Fig. 1B.
The
apparatus 10 allows work to be performed on both sides of the raised heavy
machinery
50 simultaneously, which ultimately helps to lower the downtime of the
equipment.
Should any of the second lifting devices 30 fail, the collective force can be
distributed
amongst the second lifting device(s) 30 which remain functional and/or the
first lifting
devices 20 can add more capacity because of their ability to collectively
support the full
weight of the heavy machinery 50. Similarly, in the event that one or more of
the first
lifting devices 20 fail, the second lifting devices 30 can apply extra force
to support the
weight of the upper portion 52, or the entire heavy machinery 50.
After maintenance has been performed on the lower portion 54, the heavy
machinery
50 can be lowered back to the ground surface 12. The raised support racks can
be
placed back into position below the heavy machinery 50. The locking nuts 36
can be
removed from the lower shafts 34, and the controller 40 can command the first
lifting
devices 20 to steadily reduce the lifting force so that a controlled descent
of the upper
portion 52 (and thus of the entire heavy machinery 50) can be achieved. During
descent, the second lifting devices 30 continue to collectively apply the
constant force
until the lower portion 54 is supported by the ground surface 12 or raised
support racks.
The heavy machinery 50 can then be driven or towed off the support racks.
Fig. 3 is a top view of an exemplary embodiment of the apparatus 10 without
the heavy
machinery 50 provided thereon. In this exemplary configuration, four first
lifting devices
20 are arranged in spaced apart pairs. The spacing of the first lifting
devices 20 from
one another define a perimeter 23. Four second lifting devices 30 are located
within the
perimeter 23 defined by the first lifting devices 20. The first lifting
devices 20 can be
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positioned around the sides of the upper portion 52 and linked together. For
example,
the first lifting devices 20 can be linked with transverse lifting beams 28,
which can
extend between spaced apart first lifting devices 20 and underneath the upper
portion
52. The transverse lifting beams 28 may therefore be abutted against one or
more of
the lower surfaces of the upper portion 52. Therefore, the vertical extension
of the
shafts of the first lifting devices 20 will cause the upward displacement of
the upper
portion 52. Such a configuration provides stability during lifting. Also
shown, two of the
four second lifting devices 30 are disposed towards a front of the lower
portion 54 and
directly underneath, while the other two are disposed underneath and towards a
rear of
the lower portion 54. Such a disposition of the second lifting devices 30
provides
stability to the lifting operation, and helps to distribute the constant
force.
It will be appreciated that the disposition of first lifting devices 20 is not
limited to the
embodiment shown in Fig. 3. In some embodiments, another technique for
engaging
the upper portion of the heavy machinery includes positioning the unextended
shaft of
one or more first lifting devices 20 at a height from the ground surface
greater than the
height of the lowest part of the upper portion. The output end of each shaft
can be
linked together and to the upper portion such that the vertical extension of
the output
ends causes the upward displacement of the upper portion. Yet another
technique
includes positioning the first lifting devices 20 directly underneath the
upper portion,
such that the shafts vertically extend to abut against a lower surface of the
upper
portion and transmit the lifting force thereto. Many more of these ways are
within the
scope of the present disclosure provided that they allow the vertical
extension of the
shafts, irrespective of where they are applied or where their movement
originates, to
displace the upper portion upward from the ground surface.
Referring now to Fig. 4, there is also provided a method 100 for lifting heavy
machinery
from a ground surface. The method 100 comprises a first step 102 of
positioning the
upper portion to engage a plurality of vertically extendable first lifting
devices and
positioning the lower portion to engage a plurality of vertically extendable
second lifting
devices. The first lifting devices can be positioned directly underneath a
lower surface
of the upper portion, or to the sides thereof. Indeed, the upper portion can
engage two
first lifting devices disposed towards a first end, or front, of the upper
portion, and also
engage two first lifting devices disposed towards a second end, or rear, of
the upper
portion. Positioning the upper portion may also include displacing the heavy
machinery
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over a pair of raised support racks. The second lifting devices can be spaced
apart from
each other underneath the lower portion to provide stability thereto.
As per step 104, the upper and lower portions are lifted from the ground
surface by
vertically extending the first lifting devices a predetermined length. This
can include
providing each of the first lifting devices with a maximum extension height,
where the
maximum extension height is less than the vertical extension limit of the
second lifting
device. This may help to ensure that the first lifting devices never
vertically extend a
length greater than the vertical extension limit of any one of the second
lifting devices.
Lifting in step 104 may also comprise determining a lifting force value and
dividing the
lifting force value evenly or unevenly amongst the first lifting devices. In
order to
measure the length that the first lifting devices have extended, step 104 may
also
include monitoring a vertical extension of each of the first lifting devices
with respect to
the ground surface. An initial reference point (i.e. a zero point) can be set
on the ground
surface, and the vertical extension of each of the first lifting devices can
be monitored
with respect to the initial reference point. The first lifting devices may
then be vertically
extended the predetermined length measured with respect to this initial
reference point.
Vertical extension can be accomplished to maintain the upper portion
substantially level
with the ground surface.
As per step 106, a weight of the lower portion may be held while lifting the
upper and
lower portions by vertically extending the second lifting devices to apply a
constant
force to the lower portion. As explained above, the second lifting devices
collectively
apply the constant force. Therefore, step 106 may include determining a
constant force
value and dividing the constant force value equally, or unequally, amongst the
second
lifting devices. The constant force value may be calculated to be greater than
the weight
of the lower portion and less than an overall weight of the machinery.
Therefore, the
second lifting devices only need to apply a constant force value equal to at
least the
weight of the lower portion. The constant force value can also be calculated
as the
weight of the lower portion multiplied by a safety factor between about 1.10
and about
1.30.
The method 100 may also include holding the first lifting devices at an
extension length
and continuing to apply the constant lifting force with the second lifting
devices when at
least one of the following occurs: one of the second lifting devices has
reached a
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vertical extension limit, and the first lifting devices are vertically
extended to the
predetermined length. The holding of the second lifting devices may include
bracing,
using the mechanical locks, the vertically extended second lifting devices. In
order to
support the large machinery, a lifting force value equal to the weight of the
upper portion
.. may be determined. This helps to maintains the upper portion in a raised
position and
prevent it from descending.
While illustrated in figures 2a and 2b as groups of discrete components
communicating
with each other via distinct data signal connections, it will be understood by
those
skilled in the art that the present embodiments of the controller 40 are
provided by a
combination of hardware and software components, with some components being
implemented by a given function or operation of a hardware or software system,
and
many of the data paths illustrated being implemented by data communication
within a
computer application or operating system. The structure illustrated is thus
provided for
efficiency of teaching the present embodiment.
.. It should be noted that the present invention can be carried out as a
method, can be
embodied in an apparatus, or can be provided on a computer readable medium
having
stored thereon program code executable by a processor. The above description
is
meant to be exemplary only, and one skilled in the art will recognize that
changes may
be made to the embodiments described without departing from the scope of the
invention disclosed. Still other modifications which fall within the scope of
the present
invention will be apparent to those skilled in the art, in light of a review
of this disclosure,
and such modifications are intended to fall within the appended claims.
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