Note: Descriptions are shown in the official language in which they were submitted.
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TITLE: REINFORCED LEDGER AND KNEE BRACE SYSTEM
FIELD OF THE INVENTION
The present invention relates to modular
scaffolding systems and in particular relates to a
reinforced ledger for modular scaffold systems. In a
preferred embodiment the reinforced ledger includes
bracing members in engagement with scaffold legs for
forming a reinforced knee brace arrangement.
BACKGROUND OF THE INVENTION
Perhaps the most common scaffolding system used
today includes scaffold frames releasably interconnected
by cross brace members. These prefabricated frames
include various connection points for engaging cross
brace members as well as horizontal members. The frames
are available in different configurations to suit the
specific work that is being undertaken. In applications
where high loads are required, it is common practice to
reduce the spacing between horizontal frames from the
traditional 10 foot spacing to a spacing of 6 feet or 4
feet. Speciality frames are also known that allow for an
archway to define a pedestrian or worker pathway through
the frames. The legs of these archway frames are
strengthened by an integral knee brace arrangement welded
to essentially the full height of each frame leg. These
integral braces essentially twin the leg and avoid the
need for expensive tube and clamp bracing to be secured
to the frame legs. These specialty frames are less
expensive to erect than the tube and clamp equivalent
arrangement.
One disadvantage of using speciality frames to
provide a clear passageway through the base of the
scaffold structure is that the frames are quite wide and
tall, making them unsuitable for general use. Therefore
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these frames typically have a low utilization factor
compared to a conventional frame.
A further issue associated with the use of
speciality frames is associated with multiple bays that
extend in both directions. As frames are typically
linked with cross brace members, trying to provide
pedestrian or worker passageways in both directions is
difficult as the cross brace members obstruct the free
access in the opposite direction.
Tube and clamp scaffolding systems are well
known, and essentially the workers assemble the systems
onsite and the system readily responds to changes in
configuration as the tube and clamp design provides great
flexibility. Unfortunately, with tube and clamp systems,
the cost to erect such a system is more expensive and
requires skilled labour.
Modular scaffolding systems are also known that
are generally a hybrid between the scaffold frame systems
and the tube and clamp systems. With this arrangement,
the verticals include predetermined connection members
spaced along their length, and these can engage
horizontal and diagonal bracing-type members having
connectors at their ends. With this type of arrangement,
the system can be erected more quickly, and there is a
reduced possibility that the system is not erected
properly.
Modular scaffold systems suffer from the same
shortcomings as tube and clamp scaffolds when they are
used to span across openings, or provide unrestricted
access beneath scaffolds. Single modular verticals
typically are not capable of withstanding the entire
load, and must be reinforced by a knee brace type
arrangement, or the verticals must be linked together in
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pairs or clusters in order for them to provide sufficient
stiffness. These approaches to increase load carrying
capability are expensive and require experienced erection
personnel and perhaps the services of an experienced
engineer to ensure that the resulting structure is
capable of supporting the required loads.
It is also known to use reinforced ledgers for
connecting to adjacent scaffold legs where higher loads
are being carried by the ledger. These reinforced
ledgers provide more load carrying capability along the
length thereof, however this load is effectively carried
by the legs at either end of the ledger head, and this is
often the limiting factor.
The present invention seeks to overcome a number
of these disadvantages and provide a cost effective
approach for defining pedestrian access passageways or
areas where obstructions are reduced.
SUMMARY OF THE INVENTION
A scaffolding system of the present invention has
a series of upright scaffold legs with connectors fixedly
secured along the length of each upright scaffold leg for
releasably connecting with horizontal members and/or
diagonal bracing members. These connecting members have
connecting heads at opposite ends thereof for releasable
securement to the scaffold legs. The system includes
reinforced ledgers where each reinforced ledger includes
a top chord with a connecting head at opposite ends
thereof for selective securement with the connectors of
the upright scaffold legs, and a bottom chord positioned
below the top chord and fixedly secured thereto adjacent
opposite ends of the top chord. Each reinforced ledger
includes a pair of socket tubes positioned inwardly of
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and adjacent to the ends of the top chord. The socket
tubes open downwardly and extend above the bottom chord
towards the top chord. These socket tubes are sized to
receive and engage a spigot of a vertical bracing member.
In an aspect of the invention, the socket tubes
are located at opposite ends of the bottom chord and form
a fixed structural connection between the bottom chord
and the top chord.
In yet another aspect of the invention, the
bottom chord is of a length less than the top chord and
centered beneath the top chord with the socket tube
secured at opposite ends of the bottom chord.
In yet a further aspect of the invention, the
scaffolding system includes removable vertical brace
members where each vertical brace member includes at one
end thereof, a spigot sized for receipt in and connection
with any of the socket tubes. The vertical brace member
includes an upright portion beneath the spigot and at
least one short arm extending outwardly from the upright
portion with each short arm having a connecting member.
Each short arm is positioned for engagement with a
connector of an upright to provide further support of the
reinforced ledger in which the spigot has been received.
With this arrangement, the reinforced ledger is provided
with additional support by downwardly extending vertical
support members with these vertical support members
positioned to one side of the scaffold leg, and connected
thereto by one or more releasable connecting members.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the invention are shown
in the drawings, wherein:
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Figure 1 is a perspective view of a four bay
arrangement defined by the scaffold legs, the vertical
brace members and the reinforced ledgers;
Figure 2 is a perspective view of the reinforced
ledger and an associated upright scaffold leg shown in
dotted lines;
Figure 3 is a perspective view showing the
reinforced ledger connected to two spaced scaffold legs
shown in dotted lines;
Figure 4 is a perspective view showing vertical
brace members being secured to the reinforced ledger;
Figure 5 shows the further assembly of the
vertical brace members after being inserted into the
spigot tubes;
Figure 6 shows the vertical brace members secured
to the reinforced ledger and now connected to the
scaffold legs; and
Figure 7 shows a reinforced ledger connected to
two vertical scaffold legs and associated locking pigtail
pins.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The scaffold system 2 shown in Figure 1
illustrates a modular scaffolding system using upright
vertical legs 4 having connectors 6 fixed thereto at
different spacings along the length thereof. The
vertical upright legs 4 are typical of a modular
scaffolding system where a series of rosettes are welded
or otherwise secured to the scaffold leg at fixed
spacings along the length thereof for connecting with
horizontal members as well as diagonal bracing members.
Typically, these diagonal members and horizontal members
have a connecting head at one end thereof with a wedge
member for providing a simple and efficient connection of
the members to the vertical uprights.
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Figure 1 illustrates the reinforced ledgers 16
connecting individual vertical upright legs 4. The
reinforced ledgers can also be used for connecting of
scaffolding frames having connecting rosettes or
appropriate structure. In general, reinforced ledgers
are known, and these ledger members typically include a
top chord and a bottom chord to provide the additional
load carrying capability. These known reinforced ledgers
do not include the socket tubes 22 that mechanically
connect the bottom chord 20 to the upper chord 18 as
shown in the present drawings. These socket tubes
advantageously allow connection of the reinforced ledger
to the vertical brace members 26 as shown in Figures 2
through 7.
In Figure 1, a four bay arrangement has been
illustrated where there are passageways defined in both
directions between all of the scaffold legs. The
scaffold legs have been reinforced by the vertical brace
members 16 and it can be seen that the center vertical
upright leg 4a includes four vertical brace members 26.
Each of these vertical brace members 26 is associated
with one of the reinforced ledgers 16.
Figure 2 shows details of the reinforced ledger
16. This reinforced ledger includes the top chord 18, a
bottom chord 20 generally centered beneath the top chord
and of a length shorter than the top chord. A pair of
socket tubes 22 are positioned at opposite ends of the
bottom chord 20 and form a mechanical connection of the
bottom chord to the top chord 18. The reinforced ledger
16 also includes a fixed center support 23 and triangular
gussets 25. Other bracing of the top and bottom chords
can be used.
The reinforced ledger 16 includes a center
structural member 23 extending between the top and bottom
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chords, and triangular gusset members 25. The reinforced
ledger 16 is further strengthened by the diagonal brace
members 31 and 33 that connect the socket tubes 22 to the
respective ends of the top chord 18.
Modification of the configuration of the
reinforced ledgers can occur, however the illustrated
structure effectively utilizes the socket tubes 22
provided adjacent opposite ends of the bottom chord for
advantageously releasably engaging the vertical brace
members 26 shown in Figure 4.
In Figure 4, the vertical upright legs 4 are
secured by the reinforced ledger 16. The reinforced
ledger 16 is secured to the legs due to the engagement of
the connecting heads 35 and 37 with the rosette connector
6. The vertical brace members 26 are shown aligned below
the socket tubes 22 and the spigot 30 is aligned with the
socket tube 22 for insertion therein. Each of the
vertical brace members 26 include an upright portion 28
shown with three short connecting arms 32, 34 and 36 that
extend outwardly from the upright portion 28 and have a
connecting head 38 at the end of each connecting arm.
The upright portion has been rotated to a position such
that the connecting heads 38 of the arms 32, 34 and 36
are spaced from and do not interfere with the associated
rosettes on the upright legs 4. In the position shown in
Figure 4, the vertical brace members 26 are positioned to
move upwardly such that the respective spigots 32 enter
the aligned socket tube 22. The fixed collar 41 engages
and provides a load transfer surface with the bottom edge
of the respective socket tube.
Figure 5 shows the spigots of the vertical brace
members 26 inserted in the socket tubes 22 and the
vertical brace members are about to be rotated to bring
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the connecting heads 38 into engagement with the
corresponding rosettes 6.
In Figure 6, the connecting heads 38 are now
positioned for mechanical securement with one of the
ports of the rosette connectors 6. This is accomplished
by rotating the wedge 39 of the connecting head 38
upwardly and then once it is aligned with the appropriate
hole in the rosette, the wedge is moved downwardly and
engages and draws the connector into firm engagement with
the rosette. This type of engagement is commonly used in
the system.
In Figure 7, the vertical brace members 26 are
now in engagement with the respective upright scaffold
legs 4. Key lock members 42 and 43 are shown for
engagement with the port 45 to mechanically fasten the
spigots 30 with the socket tubes 22.
In the various figures, the assembly of the
reinforced ledger to the separate uprights for the
scaffolding system, and the subsequent assembly of the
vertical brace members to the legs and reinforced ledger
are shown in a vertical orientation. As can be
appreciated, it may be more time efficient to initially
secure two scaffolding legs, the reinforced ledger and
the associated vertical brace members on the ground and
then use this as a "assembled frame" for securement in
the system. There will always be some need to assemble
the overall system in a vertical orientation; however a
number of "frames" can be pre-assembled to reduce the
overall erection time. These pre-assembled frames need
not be broken down when the job is complete and could be
stored as frames.
The four bay system as shown in Figure 1 is not
the most common or typical arrangement, as often a
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passageway for a sidewalk or walkway is only required in
one direction. For example, one common application of the
system would be the "assembled frames" of Figure 6 in
combination with traditional horizontal bracing members and
diagonal bracing members extending between frames. Such a
system would define a single passageway extending through
the frames.
The vertical brace members 26 have been described
and shown with respect to the three short arms 32, 34 and
36. As illustrated in Figure 1, the upright portions 28 of
the vertical brace members 26 extend over the major length
of the upright scaffold legs. This provides excellent
reinforcing of the scaffold legs and provides a relatively
high load carrying capability. For some applications, the
load carrying capacity may not be as great, and the length
of the vertical brace members can be reduced. For example,
a vertical brace member may only include two short arms,
and this may be sufficient for many applications. For some
applications a single arm may be sufficient. This still
provides good reinforcing of the scaffold legs, and allows
the reinforced ledger to carry the design loads.
Therefore, it can be readily appreciated that the size and
length of the vertical bracing members can change according
to the particular requirements. Furthermore, it is apparent
that within a given system the vertical bracing members can
be of different shapes to provide the required loads.
Although various preferred embodiments of the
present invention have been described herein in detail, it
will be appreciated by those skilled in the art, that
variations may be made thereto without departing from the
invention as defined in the appended claims.
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