Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to work platforms
which can be raised along a building structure, so that
workmen can effect work on the latter.
B~GKG~taTI~iD ak° T~~ TRfIY~PTTIaN
U.S. Patent No. 4,809,814 dated March 7, 1989,
entitled: SCAFFOLDING, inventor lean St-Germain, describes a
scaffolding including a pair of towers each made of tower
sections adapted to be secured in send-to-end .relation, a work
platform completely surrounding said towers and hydraulically-
operated hooks extendable and retractable along the towers and
selectively engaging steps of said 'towers to raise the
platform along the towers. Although the work platform
assembly in accordance with the above-noted invention has been
found to be a great improvement over conventional manually-
erected scaffoldings, certain inconveniences have been found
in practice, such as the need to climb down the platform onto
a suspended swing stage for ~tYae installation of cross-braces
interconnecting the towers and of anchors to secure the towers
to the building wall, these operations being effected every
time the platform is raised a certain amount. The removal of
the braces and of the anchors needs also to be effected in the
same manner every time the platform is lowered.
A further disadvantage of the scaffolding of this
prior patent resides in the fact that several work platforms
cannot be suspended at different levels from the main work
platform due to 'the existence of the cross-braces, thereby
restricting concurrently effected work at a single level,
namely the platform level.
80 Another disadvantage of the above-noted system
resides in the fact that the hydraulically-operated platform
raising means i:~ an expensive raising mechanism which also
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entails frequent maintenance due to 'the working environment in
which it is located.
Another disadvantage of the system is that for each
platform, two columns or towers are required, resulting in a
time-consuming and expensive installation for a given platform
length.
O~c'pE'L°T~B OF TIrIF~' I~lk.'IdTIOId
The general object of the present invention is the
provision of a self-raising work platform assembly designed to
overcome the above-noted disadvantages.
Another abject of the invention is to provide a work
platform assembly which is more flexible than the above-noted
system.
Another abject of the invention is to provide a work
platform assembly which is of simple and inexpensive
construction in that a single tower is required.
~ZJ 7l O~° TIE I~1E1~TION
The work platform assembly of the invention
comprises a single tower adapted to be positioned adjacent a
building structure, vertically-spaced anchor means fixed to
said tower and adapted to be fixed to said building structure
to maintain said tower upright, an elongated sleeve--like
member surrounding and movable up and down the tower and
having a longitudinally-extending slit opening at both ends of
said sleeve to clear said anchor means, guiding means guiding
the sleeves for up-and-down movement slang the tower, lifting
means interconnecting the tower and the sleeve to raise the
sleeve and allow the sleeve to be lowered by gravity slang the
tower, a first pair of joist structures, of substantially
equal length weight and weight distribution along their
length, fixed at their inner ends to opposite sides of said
sleeve and hori~antally extending in opposite direction to
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substantial7.y counterbalance each other and flooring supported
by the joist structures.
Preferably, each joist structure is formed of
modular elongated sections releasably secured in end-to-end
relations. Each modular section is preferably made of lattice
work, is box shaped and is of quadrangular cross-section
defining end portions formed with vertical members and top
transverse members, one end of each modular section having
upwardly-directed hooks ~to receive the top transverse member
of an adjacent modular section, with the vertical members of
the two modular sections in abutting relation, so as to
maintain the modular sections in alignment.
Similarly, the sleeve has vertical longitudinal
members carrying upwardly-directed hooks far receiving the
transverse member of a modular section, with the vertical
members of the same in abutment against the longitudinal
members of the sleeve to thus maintain the modular sections in
horizontal position.
Preferably, two levels of pairs of joist structures
are provided with the joist structures of the upper level
being shorter than those of the lower level, and superposed
joist structures being interconnected by guy wires at their
outer end portions.
Preferably, chain blocks are used as lifting means.
An emergency braking system is provided, which
automatically stops descent of the sleeve when the descending
speed is above a predetermined normal descending speed.
Otherwise, -the emergency braking system automatically allows
normal descending movement as well as ascending movement of
the sleeve.
A telescopic bridging frame can be used to
interconnect the outer ends of two joist structures disposed
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at the same level and belonging to two adjacent self-raising
work platform assemblies.
B1~~E~' DBBCRIET~Oai QF T~IB 1~RA~9IFIG~t
Figure 1 is a partial front elevation of the single
tower and of the two level cantilever work platforms carried
by the same;
Figure 2 is an end view, partially in section, taken
along line 2-2 of Figure 1;
Figure 3 is a plan view, partially in section, taken
along line 3-3 of Figure 2;
Figure 4 is a front elevation, taken within circle
4 of Figure 2;
Figure 5 is a partial section, taken along line 5-5
of Figure 4;
Figures 6, 6A, 6B, and (C are partial views showing
one of the emergency brake levers of Figures 4 and 5 shown in
different positions;
Figures 7, 8, 9 and 10 are partial sections, taken
along circles 7, 8, 9, and 10, respectively of Figure 1;
Figure 11 is a perspective view of one modular
section of the joist structures;
Figure 12 is a partial side elevation of two
assemblies of the invention, interconnected by a telescopic
bridging frame;
Frame 13 is a perspective view of the telescopic
frame shown within area of Figure 12;
Figure 1~ is a front elevation of one Mower section;
Figure 15 is a side elevation of the tower section;
and
Figures 16 and 17 are end views, taken along line
16 and 17, respectively, of Figure 14.
I»:'q°~~hED D~~CItI7P°.t'~ON 1.9F °fH~ ~Fi~T'~~I8E~7
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The work platform assembly of the invention
comprises a single tower 2, which, as shown in Figures 2 and
3, is secured adjacent a building structure B by a series of
vertically-spaced anchors ~ which maintain the tower 2 in
upright position. A sleeve 6 surrounds the tower 2 and is
guided along the same for up-and-down movement under 'the
action of a lifting means, namely a chain black 8. Sleeve 6
supports in horizontal position a lower pair of joists 10 and
an upper pair of joists 12. Guy wires 1~ interconnect 'the
outer end portions of the upper joists 12 to the lower joists
10. The lower joists 10 can be made longer than the upper
joists 12, in the particular example shown, 'there are twice as
long. In order to properly counterbalance the assembly of the
two resulting platforms, the joists 10 and 12 must be of
substantially equal length, of equal weight and of equal
weight distribution along their length. In this manner,
lateral tilting of the tower and of the platforms is prevented
and also the platforms can be unequally loaded up to a certain
extent, the resulting tilting force an the tower being
resisted by the anchors 4.
The joists 10 and 12 support a flooring 16 to
complete the work platform.
Referring to Figures 14 to 17, it is seen that the
tower 2 is made of tower sections. l8, adapted to be removably
secured to each other in end-to-end relationship. Each tower
section is of square cross-sectional shape, for instance 12
inches by 12 inches, and includes at the four corners
longitudinal angle bars 20 joined together by equally-spaced
transverse bars 22, 24 and diagonal bars 26 on the same sides
as bars 24. Transverse flat bars 28 and angle bars 30 are
secured at opposite ends of the angle bars 20 and are provided
with holes 32 which register in pairs to receive bolt-and-nut
means to secure the tower sections together. Transverse bars
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22 or 24 farm a series of equally spaced steps to allow a
workman to climb up the tower and attach to a selected step
the hook 34 of the primary chain 36 of the chain block 8, so
that the sleeve 6, together with the sets of platforms can be
raised or lowered along tower 2.
The chain block 8 is of conventional construction.
Its arrangement is described in more detail in applicant's
U.S. Patent No. 5,159,993 entitled: SELF-RAISING WORK
PLATFORM ASSEMBLY, issued November 9, 1993. More
particularly, the chain block housing 38 is mounted at the
tap of the sleeve 6 and the primary chain 36 extends from the
hook 34 around a return pulley 40 carried by the lower end of
the sleeve 6 see Figure l5, and finally in engagement with
the chain intermeshing driving pulley 42 within the chain
block housing 3B. Pulley 42 i.s driven through a speed
reducer, the input of which is actuated by a secondary chain
44 actuated at its lower end by an electric motor driving a
secondary pulley through a speed reducer, the whole unit,
indicated at 46, being mounted on a shelf 4$ fixed to the
sleeve 6.
Referring to Figures 2 and 3, each anchor 4
includes a bracket 50 secured to the tower 2 by a retaining
plate 52 and bolts 54. A pair of tie-rods 56, each made of
two sections interconnected by a buckle 58, are pivotally
connected at 60 to the bracket 50, and at 62 to an angle bar
64 adapted to be removably secured to the building structure
13 at the proper level. The tie-rods 56 are diverging towards
the building structure and the buckles 58 can be
independently adjusted. The proper vertical positioning of
the tower 2 is obtained and also the tie-rods resist lateral
tilting of~ the tower in all directions, including lateral
tilting in the direction of the platforms up to a certain
extent.
6
The sleeve 6 is also of square cross-section, and
includes longitudinal members 66, transverse members 68, and
diagonal members 70, all welded 'together to form a rigid unit.
As shown in Figure 3, the sleeve side facing towards each
building structure B has a longitudinal slit 72 opening at
both ends of the sleeve and serving as a clearance for the
successive brackets 50 of the anchors 4, so that the sleeve 6
cannot interfere with the anchors 4 during its up-and-down
movement along tower 2.
The sleeve 6 is guided along the tower 2 by an upper
and a lower set of guiding wheels 74 carried by ears 76 fixed
to the lower and upper end of the sleeve 6. The guiding
wheels 74 have a V-shape groove for engaging the two right
angle faces of the angle bars 20, the guiding wheels 74 being
set at 45 degrees with respect to the sides of the tower 2.
Referring to Figures 4, 5 and 7, the lower and upper
sections of the sleeve 6 are each provided with two outwardly-
protruding hooks 78 respectively secured to the two
longitudinal members 66 and a pair of brackets 80 are secured
to a transverse member 68 of the sleeve 6, vertically below
hooks 78. The hooks 78 are upwardly opening and serve,
together with the brackets 80, to secure to the sleeve the
lower and upper pairs of joists 10 and 12 respectively.
The sets of hooks and brackets 78 and 80 are
disposed on the parallel sides of the sleeve 6, which are
normal to the side provided with slit 72.
Each joist 10 or 12 is composed of one or more
modular joist sections 82, more particularly shown in Figures
1 and 7 to 11. Each joist section 82 is elongated and box
shaped, of generally rectangular cross-section, made of
lattice work including top and bottom longitudinal stringers
83, and 83a, and at each end a pair of laterally-spaced
vertical members 84 and 84a interconnected by top and bottom
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horizontal transverse members 86, 8&a, 86', 8C'a. One end of
the joist seotion $2 is provided with a pair of upwardly-
extending hooks 88 similar to hooks 78 secured to the sleeve
6. These hooks 88 are fixed to the vertical membexs 84
adjacent the top horizontal transverse member 86. The other
end of section 82 defined by members 84a and 86a, 8Ga has no
hook. All the joist sections 82 are of similar dimensions
and weight, as shown in Figure '1. The top transverse members
86a of one joist section is dizectly inserted into the hooks
78 of sleeve 5, and vertical members 84a abut directly
against the longitudinal members 66 of the sleeve 6, while
the bottom transverse member 86'a of the joist section rests
on the brackets 80, where they can be secured by bo~.t-and~nut
90 extending through registering holes of the bracl~et 80 and
IS of the bottom transverse member 86'a of the joist section 82.
The pair of hooks $$ of the joist 'section 82, which are now
at the outer end of the joist, are adapted to receive the top
transverse member 86a of the next joist section, as shown in
Figure 10, and the vertical members 84, 84a of the two
contiguous joist sections abut each othex and they are
preferably joined together at their lower ends by a clamp 92.
The pair of hooks 8B of the outermost joist section
82 of the upper joist 12 ara used to attach the upper end of
the guy wire 14, as shown in Figure 8. For this purpose, the
upper end of each guy wire 14 is attached to the middle of a
transverse retaining member 94 releasably inserted within
these hooks 88. Similarly, the lowex end of the guy wire 14
is attached to the middle of a transverse retaining member
96, which is removably retained underneath the top
longitudinal-stringers 83 of joist section 82 and against a
pair of vertical members 100 intermediate the ends of the
outermost joist section 82 of the lowez~ joist 10. In this
manner, the guy wixes which protrude from the center plane of
the lower
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joist allow the workman on the lower platform to move on
either side of the guy wire. Each guy wire 14 is made of two
section interconnected by a buckle 102 for adjusting the
effective length of the same.
Figures 2, 7, and 8 show the construction of the
flooring 1&. It is composed of a plurality of channels 104
disposed side by side and longitudinally extending with
respect to the joists 10 ox 12 and supported by transverse
tubular membexs 7.06 resting on the top stringers 83 of the
joist sections 82 and secured thereto by a pair of ears 108,
depending from and fixed to the transverse member 106 and
straddling the top stringer 83 of the joist section 82 and
pressed against the same by a bolt--and-nut 110.
As shown in Figure 2, both the lower and upper
platforms can be made much wider than the sleeve 6 and
provide a passage from one side to the other of the tower 2.
Referring to Figures 12 and 13, it is seen that two
work platform assemblies in accordance with the invention can
be arranged side by side along a building wall, with the
2D lowermost platforms at the same level and interconnected by a
bridging frame 112, also supporting the flooring 16
consisting of the channels 104. Bridging, frame 112 includes
two telescopic sections, namely: outer section 17.4 and inner
section 116. Outer section 114 forms a rectangular frame,
made of tubular members, and its longitudinal members 118 are
open at one end to telescopically xeceive the legs of the U-
shaped inner telescopic section 116_ These legs are provided
with an outwardly-protruding stop pin 120 extending through a
slot 122 of longitudinal members 118, so as to prevent
separation of the two sections 114, 116, the stop pins 120
reaching the ends of the slots 122 during extension of the
bridging frame 112.
9
The ends of the bridging frame 112 are inserted
within the hooks 88 protruding from 'the lower joist 10 of the
two adjacent platform assemblies.
The sleeve 6, together with the lower and upper
cantilever platform assemblies cax-ried thereby, can be raised
along the tower by the chain block 8, a stroke depending on
the location of the chain hook 34 on the tower 2 above tkxe
lower return pulley 40.
The platform assembly is lowered under gravity under
the control of the chain block 8. Therefore, the platform
assembly descends at a generally uniform slow speed which is
called a predetermined descending speed. An emergency braking
system is provided to automatically stop descent of 'the
platform assembly in an emergency wherein the above-noted
predetermined descending speed is exceeded, due, for instance,
to breakage of the primary cable or for any other reason.
The emergency braking system is more particularly
illustrated in Figures 4, 5, and ~, 6A, 6B, and 6C. Each of
two opposite sides of the sleeve 6 carries a series of three
vertically-spaced levers 124 pivoted intermediate its ends for
pivotal movement in a vertical plane about a horizontal pivot
pin 126 carried by ears 128 fixed to a transverse member 130
fixed to upright reinforcing member 131 of the sleeve 6. The
pivot pin 126 is located upwardly and inwardly with respect to
the transverse member 130, so that the latter acts as an
abutment member which limits pivotal movement of said lever
124 between a vertical limit position, as shown in Figure 6,
and a horizontal limit position, as shown in dotted line in
Figure 6 and also in Figure 6C. when lever 124 is horizontal,
its inner bevelled end 132 is in the path of the successive
steps of sleeve 6 formed by its transverse bars 22 and when it
comes to rest on a sleeve step 22, the sleeve 6 cannot descend
any longer. This sleeve-stopping position is shown by the
lower pair of levers 124 in Figure 5.
The outer end of each lever 124 is enlarged to form
a counterweight 134, in the form of a cam which laterally
upwardly protrudes from the top side of the lever when the
la~t~ter is seen in horizontal limit position. This cam-shaped
counterweight 134 defines outwardly-converging outer and inner
cam edges 136 and 138 respectively. Each lever 134 is free to
pivot between its horizontal and vertical limit positions.
The cam-shaped counterweight 134 confers a greater weight to
the part of the lever external to the pivot pin 'than the part
of the lever internal to said pivot pin. When the bevel end
132 is downwardly extending, the lever is in an unstable
equilibrium in that from a predetermined downwardly-inclined
position, approximately shown in Figure 6A, the lever will
automatically return to its vertical limit position under the
action of the counterweight 134, if the lever has not reached
this predetermined inclined position when pivoting from the
vertical limit position to the horizontal limit position.
2p If, during this movement, the lever moves past said
predetermined inclined position, then the counterweight 134
will automatically cause the lever to pivot further until it
reaches its horizontal limit position. Assuming the lever is
in vertical position, as shown in Figure 6 during raising
movement of the sleeve 6 along the tower, the outer cam edge
136 abuts the underside of successive steps 22 of the tower 2
at a slow enough speed so that tine lever cannot pivot beyond
the above--noted predetermined inclined position; past each
step, the lever automatically returns to its vertical
position. The same action occurs when the sleeve descends
along the tower at a slow, normal speed as produced by the
operation of the chain block. As shown in Figures 6A and 6E,
the inner edge 138 successively abuts against the top edge of
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the sleeve step 22 . with insufficient force to cause
anticlockwise movement of the lever past Sts predetermined
inclined position, so that the lever automatically returns to
its vertical limit position, as shown in Figure 68. Thus,
normal descending movement of the sleeve 6 3s not prevented.
However, should the descending movement exceed the
predetermined normal speed, then the inner cam edge 138 will
strike the top edge of the transverse step 22 with sufficient
force to cause counterclockwise pivotal movement of the lever
~0 past its equilibrium~inclined position and the counterweight
134 will automatically cause the lever to further pivot to
its horizontal limit position in which, as seen in Figure 6C,
the bevelled inner end 132 will engage the next lower step 22
and stop the sleeve 6.
In order to prevent the free fall of the platform
assembly through a distance less than the vertical distance
between the successive steps 22 of the tower, there are
provided a set of three levers 124 on each side of the tower
and the vertical distance between the successive levers of
2o each set is less than the vertical distance between the.
successive steps 22.
In the use of the invention, a first series of
tower sections 18 are first assembled on the ground and then
lifted with a tower crane, or the like, to an upright
position, and additional towers sections can be added at
ground level with the lowermost section inserted into upright
sleeve 6. Once the desired height has been achieved, the
whole tower is anchored to the building structure B by means
of the anchors 4. The upper and lower platform assemblies
3D are assembled and fixed to the sleeve 6 at ground level. The
work platform arrangement is very inexpensive and cax~ be
adapted for a variety of applications, since a single tower
is used.
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