Note: Descriptions are shown in the official language in which they were submitted.
CA 02639106 2008-08-25
LOAD TEST SYSTEM
FIELD OF THE INVENTION
[0001] This invention relates to a system for load testing devices such as for
use with
"below-the-hook lifting devices." More particularly, the invention relates to
such a test system
which provides a standardized methodology with recorded results which can be
used to ensure
compliance with regulations from relevant government agencies.
BACKGROUND OF THE INVENTION
[0002] A "below-the-hook lifting device" is a sling, hook, magnet, or vacuum
device,
beam or fabricated structural device that is suspended from the hook of an
overhead crane or
hoisting device, and used to lift an object. They are also sometimes referred
to as overhead
lifting devices. Under current standards for the design and manufacture of
"below-the-hook
lifting devices," mandatory load testing is not required of the manufacturer.
On the other hand,
regulatory agencies such as OSHA in the United States, often demand testing
and the burden
of such testing often falls on the user to provide certification that the
lifting device has been load
tested prior to use. Failure to comply with testing can result in large fines
being levied on the
user.
[0003] Many manufactures of "below-the-hook lifting devices" (hereinafter
"lifting
device," "test device" or "test lift device") produce such lift devices in
batches of several hundred
in a single production run. In order to provide testing certification for end-
user purchasers, the
manufacturer may choose to load test random numbers of lift devices produced
in a single
production run. This practice does not guarantee that all produced lift
devices satisfy the
regulatory standards, and it is preferable that every lift device produced be
load tested before
delivery to a customer. Unfortunately, such a task has to date been
prohibitably expensive.
[0004] For the above reasons, what is needed is a load test system which can
be used
by a manufacturer to test every lift device produced in a cost effective way,
and with the ability
to provide accurate certification to an end-user purchaser that the lift
device purchased has
been tested and satisfies regulatory standards.
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SUMMARY OF THE INVENTION
[0005] The invention is a load test system for lift devices which includes a
test bed
frame. The test bed frame extends horizontally along a first axis. Two rolling
beams are
movably mounted securely in the test bed frame for being moved to desired
positions along the
first axis within the test bed frame and, in a specific aspect, the rolling
beams can be locked into
position therein. The rolling beams include plural attachment locations for
attaching a test lift
device thereto. A hydraulic power station is spaced from the test bed frame
along a second axis
perpendicular to the first axis. The hydraulic power station includes a
connecting line connected
to a hydraulic cylinder in the power station at one end, and connectable to a
test lift device at
another end for applying a load to the test lift device when the test lift
device is attached to the
test bed frame and to the hydraulic power stations hydraulic cylinder. Beam
members serve to
connect the hydraulic power station and the test bed frame to form a rigid
structure.
[0006] In a specific aspect, the rigid structure is arranged to have the
connecting line
extend horizontally, and includes a winch and slack take up cable associated
with the
connecting line for taking up any slack in the connecting line when connected
to a test lift device
to be tested resulting from gravitational pull toward the floor of the rigid
structure.
[0007] Embodiments include at least one load sensor associated with the
hydraulic
cylinder for measuring a load applied to the test lift device. At least one
camera may be
provided for visually recording a load test conducted on the test lift device.
[0008] A hardened monitoring and control station may also be provided separate
from
the rigid structure, and may be enclosed and hardened to protect a user
conducting the test in
the event of catastrophic failure and debris resulting from failure of a test
lift device during a test.
Recording devices and display devices may also be located in the monitoring
and control station
to record data picked up by the load sensors resulting from the test, as well
as to visually record
the test through use of the camera, and to display the data and images.
[0009] These and other advantages and features that characterize the invention
are set
forth in the claims annexed hereto and forming a further part hereof. However,
for a better
understanding of the invention, and of the advantages and objectives attained
through its use,
reference should be made to the Drawings, and to the accompanying descriptive
matter, in
which there are described exemplary embodiments of the invention.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Fig. 1 shows in perspective view a load test system in accordance with
the
invention with some components removed for the sake of clarity.
[0011 ] Fig. 2 is a partial view of a rolling beam viewed from the front as
mounted on the
test bed frame.
[0012] Fig. 3 is a partial view of a rolling beam viewed from the rear as
mounted on the
test bed frame.
[0013] Fig. 4 is a top plan view of the load test system rigid structure.
[0014] Fig. 5 is a side view of the load test system rigid structure.
[0015] Fig. 6 is a perspective view of the hydraulic power station.
[0016] Fig. 7 is a side view in partial cross section of the hydraulic power
station.
[0017] Fig. 8 is a view in disassembled form of a portion of the hydraulic
power station.
[0018] Fig. 9 is a partial perspective view of the load test system shown
testing a forklift
spreader.
[0019] Fig. 10 is a partial perspective view of the load test system shown
testing a
straight piece of chain.
[0020] Fig. 11 is a partial perspective view of the load test system shown
testing a
telescopic spreader.
[0021 ] Fig. 12 is a partial perspective view of the load test system, shown
with a mesh
wire assembled thereon.
[0022] Fig. 13 is a perspective view of the circled portion of Fig. 12,
showing how the
wire mesh slides open and closed, and is attached to the rigid structure.
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DETAILED DESCRIPTION OF THE INVENTION
[0023] In one respect, embodiments consistent with the invention may
capitalize on a
load test system that can test a wide variety of shapes and sizes, based in
part upon a rolling
beam feature, and the size of the load test system which provides numerous
anchoring
locations so that the test lift device can be properly evaluated and tested
under conditions
substantially approximating actual field conditions.
[0024] Fig. 1 illustrates in perspective view a load test system 11 in
accordance with the
invention, with some of the components thereof not shown for the sake of
clarity. A test bed
frame 13 extends horizontally along a first axis and includes rolling beams 15
which typically
have a number of connection points spaced equally along the vertical axis of
the beams 15 for
attachment of pad eyes 17. The beams 15 can roll back and forth along the test
bed frame 13
as more clearly shown in Figs. 2 and 3 through the means of rollers 101.
Securing tabs 19 on
the rear side of the test bed frame 13 serve to secure the rolling beams 15 on
the test bed
frame 13 when undergoing a load test and resulting in forces applied in the
direction of the
arrow 18 shown in Figs. 2 and 3. Optionally, rolling beams 15 can be locked in
place to prevent
further horizontal movement.
[0025] A hydraulic power station 41 is provided along an axis perpendicular to
the test
bed frame 13 and includes a hydraulic ram or cylinder with a connecting line
as shown and
described hereafter, for applying a load on a test lift device secured to the
test bed frame 13, for
example, at the pad eyes 17.
[0026] The hydraulic power station 41 also includes a winch arrangement, as
described
hereafter, for taking up slack on a horizontally extending connecting line
connected to a test lift
device. The winch arrangement is powered by hydraulic fluid passing through
hydraulic winch
lines 49 and 51. Hydraulic fluid is also passed through hydraulic pull and
push lines 43 and 45
for powering the hydraulic ram/cylinder. The pressurized hydraulic fluid is
provided by hydraulic
pumping unit 47 shown separate from the hydraulic power station 41.
[0027] Optionally, a hydraulic pressure meter (not shown) can be connected to
the
lines 43 and 45 and housed in the monitoring and control station. The reading
of the pressure
from the meter can serve as an indirect indicator of a load placed on a test
lift device.
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[0028] As may be appreciated, the hydraulic power station 41 may also include
a load
cell connected to the hydraulic ram to transmit data through wire 55 to a load
cell read out 57.
One or more cameras 53 may also be positioned for recording a test and may be
connected to
a display device 59 within a monitoring and control station, which is separate
and distinct from
the location where the tests are conducted.
[0029] The hydraulic power station 41 is connected to the test bed frame 13
through
means of upper beam members 21 and lower beam members 31. The lower beam
members 31 are preferably recessed (such as in a floor) to allow test lift
devices to be passed
into the rigid structure, which is made up of the connection of the test bed
frame 13 beam
members 21 and 31 and hydraulic power station 41.
[0030] With respect to the monitoring and control station, although not shown
in an
enclosed area, the monitoring and control station is an optionally separate
room with a harden
enclosure (not shown) to protect the operator against catastrophic failure and
debris resulting
from such failure when a load test is conducted on a test lift device. A
display and load cell read
out may be connected to recording devices as part of operating control box 61
to provide a
permanent visual record and read out of a load applied during a test, and the
operation of the
test lift device in response to such load during the test being conducted.
[0031 ] For ease of further understanding, it is noted that Figs. 4 and 5
illustrate in
top-plan view and side view of the rigid structure of the load test system 11
of the invention.
[0032] The hydraulic ram or cylinder arrangement of the hydraulic power
station 41 is
shown in greater detail in Figs. 6-7. As shown in Figs. 6-7, a pulley 105 with
a winch 107
arrangement can be connected to the connecting line 106 for the test lift
device to pull on the
connecting line 106. The connecting line 106 may be a chain in one exemplary
embodiment.
Slack in the connecting line 106 is optionally taken up by pulling the
connecting line along line X
(shown in Fig. 6) to bring it into a taught horizontally extending state upon
actuation of hydraulic
ram 103. The ram 103 includes a hydraulic cylinder, and no movement is wasted
by taking up
slack along direction X. As will be more readily appreciated, the hydraulic
power station with the
hydraulic ram 103 can also pivot about a pivot point along the arrow Y as
shown in Fig. 6,
depending on the lift device being tested.
[0033] The components making up the hydraulic ram 103 are further shown in
Fig. 8
and include an outside cylinder assembly 201 which fits over an inside
cylinder assembly 211.
CA 02639106 2008-08-25
The outside cylinder assembly includes a cable pulley 205 assembled on a cable
pulley
assembly 203 through pin 207. A load cell 55 is located on the inside cylinder
assembly in
association with hydraulic cylinder 213, which when actuated through hydraulic
fluid pressure,
moves rearwardly along the direction of arrow X of Fig. 6 towards a cylinder
endplate 215 and
backstop block 217.
[0034] Figs. 9-11 illustrate various tests being conducted with the load test
system 11 of
the invention. In the case of Fig. 9, a forklift spreader 301 is attached to
the rolling beams 15 at
the pads 17, and with the rolling beams 15 being placed at selected locations.
The connecting
line 106, preferably a cable, is connected to the forklift spreader 301. A
load is applied along
the direction of the arrow shown in association with the connecting line 106.
[0035] Fig. 10 illustrates a load test system 11 conducting a test on a chain
305 which
replaces connecting line 106. The chain 305 is put under stress by attachment
to a central
support beam at an anchor point 303 having a clevis adaptor. In the case of
Figs. 9 and 10 as
well as Fig. 11, the top structure, i.e., beam members 21, of the test load
system has been
removed for clarity of understanding.
[0036] Fig. 11 illustrates a load test on a telescopic spreader 307. Shackles
connect the
spreader 307 to the rolling beams 15 of the test bed frame 13. Cables 309
connect the
spreader to the connecting line 106.
[0037] Figs. 12 and 13, respectively, illustrate in perspective view a barrier
mesh 401
which can be attached around the load test system 11 to prevent debris
resulting from a test
failure from flying out of the rigid structure. The mesh 401 can be arranged
in two substantially
parallel layers as an inner and outer layer of mesh. The mesh 401 is slideably
mounted in
connection with the beam members 21 and 31 so as to allow an opening 403
resulting from
sliding motion. Once the mesh 401 is closed, it can be secured through
attachment holes 405
to provide a more rigid structure and protection for those around the load
test system 11.
[0038] It will be appreciated that test load capabilities for the system can
be engineered
in a conventional manner. For example, a system capable of applying a load of
750,000 lb may
be engineered for use with loads of up to 600,000 lb. for periods of about 3
to about 5 minutes
on a test lift device. The extra capacity provides a margin of safety.
Further, as will be
appreciated, through the use of appropriate jig arrangements, such test loads
can be effectively
multiplied by factors of 3 to 5 times the design tolerances.
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[0039] While the present invention has been illustrated by a description of
various
embodiments and while these embodiments have been described in considerable
detail, it is not
the intention of the Applicants to restrict, or any way limit the scope of the
appended claims to
such detail. The invention in its broader aspects is therefore not limited to
the specific details,
representative apparatus and method, an illustrative example shown and
described. According,
departures may be made from such details without departing from the spirit or
scope of
Applicants' general inventive concept.
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