Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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FIELD OF THE INVENTION
The present invention relates to self raising
' S platform assemblies, and more particularly to the means for
raising such platforms.
BACKGROUND OF THE INVENTION
U.S. patent n°4,809,814 issued in 1989 to JEAN ST
GERMAIN shows a scaffolding with a platform raising system
(figure 7) comprising an arm 84 and a ram member 106 that
work together to raise (or lower) the platform 42. The
platform 42 is vertically movable along an upstanding post
30 and is symmetrically positioned thereon. To raise
platform 42, ram member 106 upwardly extends its piston rod
112 which slidably and pivotably engages, with its upper
end, successive transverse bars or steps 38 of post 30. A
guide bar 120 is provided to slidably engage each
successive step 38 and prevent piston rod 112 from abutting
against the lower portion of said steps. When its stroke
is complete, piston rod 112 is retracted by its cylinder
108 and downwardly abuts with a hook member 118 against a
step 38; therefore, when its stroke is reversed, ram member
106 raises platform 42. Arm 84 engages with a hook member
90 steps 38 on the opposite side of post 30, while ram
member 106 is in its upward stroke, to uphold platform 42.
Arm 84 is pivotable and is also equipped with a guide bar
98 to clear each successive step 38 as platform 42 is
raised by ram member 106. Piston rod 112 has an upward
stroke allowing it to move two steps at a time, to
accelerate the raising of the platform. To lower the
platform, however, an operator must manually pivot arm 84
(and a second security arm 84') to allow them to clear each
successive step 38.
U.S. patent n°5,368,125 issued in 1994 to the
present applicant shows another platform raising system for
raising a work platform 24 along a tower 2. Figures 9 to
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20 show different embodiments of the raising system, though
the idea is essentially the same in each embodiment.
Figure 9 shows that the platform raising system comprises
two power actuated hydraulic rams 36 each having a hook
member 50 pivotably installed at the upper end of their
piston rod. Biasing means 54, 56, 60, 62 link the hook
members 50 of the two rams 36 in an opposite simultaneous
pivoting movement, so that hooks 50 may pivotably engage or
clear the bars or rungs of the tower frame structure (as in
the JEAN ST-GERMAIN patent). To raise the work platform to
which the lower part of rams 36 are attached, the latter
extend their piston rod upwardly. The inclined surfaces 70
of hooks 50 slidably engage each successive rungs 10 of the
tower frame structure to pivot hooks 50 and allow them to
clear each of said rungs 10. A spring 62 pivots hooks 50
inwardly so that they may engage a corresponding step 10
once a rung 10 is cleared. When the downward stroke of
rams 36 is initiated, hooks 50 therefore downwardly abut
against, in a hooking engagement, steps 10 and the
retraction of the rams' piston rods results in the raising
of the work platform. During the upward stroke of rams 36,
latching levers 72 abut against steps 10 to sustain the
work platform (figure 9a). Levers 72 can pivot to clear
each successive step 10 while they are raised with the work
platform during the upward stroke of rams 36. During the
lowering of the platform, an operator must manually pivot
latching levers 72 to their rung unlatching position in
which the platform may be lowered without hindrance to the
platform lowering operation.
Both of the previously mentioned patents thus
include a work platform which can be raised (or lowered)
along a single tower through the instrumentality of powered
rams that pull the work platform by hooking themselves on
successive rungs of the tower. These patents are
functional, though the raising or lowering of the platform
is a relatively slow operation. Also, an operator is
needed to manually pivot the arm 84 (in the JEAN ST-GERMAIN
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3
patent) or the latching levers 72 and hook releasing handle
66 (in the ANDRE ST-GERMAIN patent) to allow the lowering
of the work platform.
It is an object of this invention to provide a
self raising system for a work platform.
It is another object of this invention that_the
raising system be faster that the existing systems.
It is yet another object of this. invention that
the platform lowering operation be accomplished without the
constant implication of an operator.
Another object of the invention is that the
system of the character described be fail-safe.
SUMMARY OF THE INVENTION
The present invention relates to a platform
raising system in a scaffolding for raising a work platform
along a tower, said platform being sustained by a sleeve
member positioned around said tower, almost encircling it
completely, said sleeve member being movable along said
tower, said tower having a plurality of approximately
parallel and equally spaced rungs, said raising system
being installed on said sleeve member, said raising system
comprising two rams pivotably attached to said sleeve
member and having piston rods movable from a retracted
position to an extracted position and at the end of which
are pivotably installed corresponding hook members, said
rams being connected to power means and control means that
simultaneously activate each ram in up and down movement
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but in alternate directions, first pivoting means for
pivoting said hook members from a hooking position to an
unhooking position under the action of said rams, said
raising system further comprising synchronizing means for
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one of said hook members abutting against one of said rungs
in said hooking position at any given time to sustain said
Preferably, said sleeve member is raised or
lowered of a distance approximately equal_to the distance
between two successive rungs under the action of each ram,
the strokes of said rams being at least equal to slightly
more than the distance between two successive rungs.
Advantageously, said first pivoting means are
inclined surfaces on said hook members, said inclined
surfaces being slidably engageable with each successive
rung to pivot said hook members in said unhooking position.
Preferably, said hook members have biasing means
for pivoting them from said unhooking position to said
hooking position when said inclined surface is not in
contact with one of said rungs.
Advantageously, said platform raising system
comprises second pivoting means for pivoting said hook
members from said hooking position to said unhooking
position, said second pivoting means comprising a latch
lever member pivotable between a latched position and an
unlatched position, said second pivoting means being
gradually activated during the extension stroke of said
rams from an inactive position when said piston rods are in
said retracted position, said second pivoting means
pivoting one of said hook members only if: a) said hook
member is not bearing on any one of said rungs in a hooking
engagement; and b) said latch lever member is in said
unlatched position.
Preferably, a latch handle is provided to
manually force said latch lever member into said latched
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position or into said unlatched position.
Advantageously, said second pivoting means
further comprise at least one spring for each of said rams,
said spring being attached to a corresponding one of said
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sleeve member at its second extremity, said spring being at
its equilibrium state when said corresponding piston rod is
Preferably, said hook members have biasing means
for pivoting them from said unhooki-ng -position to said
hooking position when said second pivoting means are not
pivoting them into said unhooking position.
Advantageously, said synchronizing means are a
pair of parallel toothed racks engaging peripherally a
complementary gear wheel on opposite sides of the latter,
each one of said racks being rigidly linked to a
corresponding one of said hook members and said gear wheel
being rotatably carried by said sleeve member.
Preferably, said platform raising system further
comprises a security braking system, said braking system to
be activated only if said sleeve member moves generally
downwardly along said tower at a specific speed or faster,
said specific speed being considerably faster than the
speed at which the sleeve member moves along said tower
during its use.
Advantageously, said braking system comprises a
rocking member pivotable between a rung engaging and a rung
clearing position, a retainer arm pivotable between a first
and a second limit position, said retainer arm retaining
said rocking member in said rung clearing position when it
is in said first limit position, biasing means for pivoting
said rocking member in said rung engaging position when
said retainer arm is in said second limit position and a
finger member for pivotable abutment against each of said
successive rungs, said finger member pivoting on itself
when the speed of said sleeve member is lower than said
specific speed and pivoting said retainer arm from said
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first limit position to said second limit position when the
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speed of said sleeve member is greater than said specific
speed.
DES $IPTION OF THE DRAWINGS
In the annexed drawings: '
Figure 1 is a partial elevation of a tower and
work platform assembly together with a platform raising
system according to the invention;
Figure 2 is a partially fragmented elevation, at
an enlarged scale, of the platform raising system of figure
1, partially showing the tower and work platform;
Figures 3 to 5 are sequential partial elevations
of the tower showing the work platform and raising system
at three different heights on said tower;
Figures 6 to 8 are cross-sectional views, at an
enlarged scale, taken along lines 6-6, 7-7 and 8-8 of
figures 3, 4 and 5, respectively;
Figure 9, on the fourth sheet of drawings, is
similar to figures 6 to 8, but showing the hook member at
a different position;
Figure 10 is an elevation, at an enlarged scale,
taken in the area circumscribed in line 10 of figure 1;
Figure 11 is similar to figure 10, but showing
the latching lever member in its unlatched position;
Figure 12 is a partial cross-sectional view, at
an enlarged scale, taken along line 12-12 of figure 8;
Figure 13 is similar to figure 12, but showing
the latching lever member in its unlatched position;
Figure 14 is a partial cross-sectional view taken
along line 14-14 of figure 12;
Figure 15 is a partial fragmented elevation, at
an enlarged scale, of the raising system of figures 1 and
2, showing more particularly the toothed racks and the gear
wheel of the invention;
Figure 16 is a partial cross-sectional view, at
an enlarged scale, taken along line 16-16 of figure 15;
Figure 17 is a partial cross-sectional view, at
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an enlarged scale, taken along line 17-17 of figure 2,
showing the security braking system;
Figures 18 and 19 are similar to figure 17, but
the security braking system is in different sequential
positions;
Figure 20 is a cross-sectional view taken along
line 20-20 of figure 17;
Figure 21 is a schematic view of the hydraulic
circuit of the platform raising system of the invention;
Figure 22 is a side view of the control handle
and the corresponding hydraulic connections therewith;
Figure 23 is a perspective view of the sleeve
member that is destined to move along the tower, the
position of the latter being suggested in dotted lines;
Figure 24 is a perpective view, at an enlarged
scale, of the attachment means for the modular work
platform;
Figure 25 is a top plan view of modular
attachment means;
Figure 26 is a cross-sectional view taken along
line 26-26 of figure 25;
Figure 27 is a cross-sectional view, at an
enlarged scale, taken along line 27-27 of figure 1;
Figure 28 is a view, at an enlarged scale, of the
area circumscribed in circle 28 of figure 27;
Figure 29 is a cross-sectional view taken along
line 29-29 of figure 28;
Figure 30 is a partial edge view of a tower post,
at an enlarged scale, showing the modular attachment means
of the tower; and
Figure 31 is an exploded perspective view of the
modular attachment means of figure 30.
DETAIT_,ED DEBC_R_T_pTTON OF THE EMBODIMENTS
Figure 1 shows a scaffolding 38 comprising a
tower 40 which rests on - and is attached to - a base 42
securingly anchored to the ground G, e.g. with bolts 44.
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Tower 40 is of the type described in the above-mentioned
patent 3,368,125, except for a few improvements which will
be described later, and comprises inter alia a plurality of
generally horizontal and vertically equally spaced rungs
45. Tower 40 is secured to the wall (not shown) of the
structure on which work is done and is spaced therefrom
through the instrumentality of a plurality of wall anchors
no -- shown, suc as ~~ i~~ -
Patent No. 3,368,125. A sleeve member 46 is movable along
tower 40, sleeve member 46 having a-rectangular cross-
section (figure 23) and being positioned around tower 40,
almost encircling it completely. Sleeve member 46 has a
vertical opening 47 allowing it to move along tower 40
without hindrance from the wall anchors. A work platform
(figure 1) 48 is removably attached to sleeve member 46 in
a manner which will also be described later.
Figure 2 shows a platform raising (and lowering)
system 50 according to the invention. Raising system 50
comprises two powered rams 52, 52 that are hingedly
attached, at the lower end of their cylinder, to sleeve
member 46 through the instrumentality of ears 54 and bolts
56.
Each ram 52 has a hook member 58 (figures 2 and
6 to 9) pivotably attached at the free end of its piston
rod 52a by a hook bolt 59. Hook member 58 has an inclined
upper surface 60.
In use, to raise work platform 48, hydraulic
power means 62, shown in figure 1 (which can be, for
example, an internal combustion engine coupled to an oil
pump), simultaneously activate each ram 52 in up and down
movement but in alternate directions. The piston rod 52a
of the first ram is extracted from the cylinder and the
corresponding hook member 58 is moved upwardly from its
initial resting position on a rung 45. Hook member 58,
originally in its generally vertical hooking position,
slidably engages with its inclined surface 60 each
successive sliding member 64 fixed to rungs 45 (figure 7),
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CA 02288162 1999-10-29
9
being forced into its unhooking position. After sliding
along sliding member 64, hook member 58 is biased to its
hooking position through the instrumentality of a pair of
hook springs 66, once it vertically clears the
corresponding rung 45 (figure 8). Its extension stroke
finished, the first ram 52 proceeds to its retraction
stroke, which will engage its hook member 58 on the rung 45
(figure 9). Since work platform 48 is hingedly fixed to
rams 52, the retraction stroke of one or the other rams 52,
52 results in the raising of platform 48.
Since both rams 52 work simultaneously but in
alternate directions, while the first ram 52 is in its
extension stroke, the second ram 52 is in its retraction
stroke, its hook member 58 therefore bearing on a rung 45.
The extension stroke of one piston rod 52a is equal to at
least slightly more than the distance between two
consecutive rungs 45. Consequently, since both the
extension stroke of one ram 52 and the retraction stroke of
the other ram 52 are simultaneous, the work platform 48
moves upwards of a distance approximately equal to the
distance between two consecutive rungs during one ram
stroke. Also, since there always is at least one hook
member 58 resting on a rung 45, work platform 48 is always
prevented from falling freely along tower 40. When a hook
member 58 bears on a rung 45 (figure 9) and that the
corresponding ram 52 begins its retraction stroke, hook
member 58 may pivot slightly around rung 45 due to the load
sustained by ram 52. This is especially true if the rung
45 has been worn and that its corners are rounded. Figure
9 shows that sliding member 64 will then provide a support
for the bearing surface 67 of hook member 58 and that the
latter will therefore abut against sliding member 64 due to
the torque induced in ram 52. This torque results from the
fact that ram 52 is slightly inclined, because its lower
portion is pivotally attached at 59 to sleeve member 46 and
its upper portion (hook member 58) rests on tower 40.
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Figure 2 shows a control handle 68, linked to
hydraulic power means 62, which can be positioned in three
different modes of operation: a) platform raising mode;
__ _._b)platform lowering mode; and c) inactive -mode. --The -
5 modes are explicit, and control handle 68 therefore allows
an operator to control the platform raising system 50 in
any of those three modes.
Figure 2 suggests with arrows a, that
hydraulic power means 62 are linked to rams 52. Hydraulic
10 flow input arrow 70a shows where the fluid is inserted in
the ram 52 that is on the verge of starting its extraction
stroke, while hydraulic flow output arrow 70b shows the
fluid output of the ram 52 that is about to begin its
retraction stroke.
Figures 3 to 5 show three different consecutive
positions of the sleeve member 46, work platform 48 and
platform raising system 50 along a same section of tower
40. It can be seen that the rams 52, as previously stated,
have an extension stroke equal to slightly more than the
distance between two rungs 45. The upward movement of work
platform 48 during this operation is substantially
continuous since each step is done almost immediately after
the previous step is finished. Also, since the platform
may be raised in a continuous manner, the platform raising
system 50 is relatively faster than the conventional "stop
and go" systems.
Figures 10 to 13 show that, to lower work
platform 48, there is provided a latch handle 72 pivoted
around a pivot screw 74 at the first end of a slider arm
76, which is secured to the block fastened to piston rod
52a and carrying pivot bolt 59 of hook member 58 (see
Figure 8 and 12). Slider arm 76 is slidably guided,at its
second end in a rail 78 (figure 2) which is fixedly
anchored to sleeve member 46. Slider arm 76 can therefore
freely slide vertically along rail 78 to follow
corresponding hook
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CA 02288162 1999-10-29
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member 58 during each stroke of ram 52.
When latch handle 72 is pivoted downwardly by an
operator, as suggested in figures 11 and 13, a U-shaped
link 80 pivots a latch lever member 82 generally downwardly
around a pivot pin 84 from its latched position to its
unlatched position. Indeed, figure 14 shows that the first
and second legs 80a and 80b of U-shaped link 80 are
rotata~ly a ac a o a c an -~h--ice-
member 82, respectively. First leg 80a is attached non-
coaxialy relative to pivot screw 74 on latch handle 72 so
as to provoke the generally downward movement of its second
leg 80b around pivot pin 84, therefore forcing latch lever
member 82 into its unlatched position
If there is no pressure applied on latch handle
72 by an operator, the position of latch lever member 82
will depend on the state of a pair of springs 86, 86.
Figures 2 and 6 show that springs 86 are attached at their
upper end to a spring plate 88 (fig. 6) and at their lower
end to a respective piston 90 which is slidably and
vertically movable inside a bored piston guide 92 fixedly
but adjustably attached to a vertical beam 94 of sleeve
member 46 structure (Figure 2).
If latch handle 72 is not pivoted downwardly,
link 80 will keep latch lever member 82 in its latched
position (figures 10 and 12).
Figures 10 to 13 show a wire 96 adjustably
attached, e.g. by means of a set screw 98, at its first
extremity to hook member 58 and passing through bores in
slider arm 76 and in latch lever member 82. A retainer cap
100 is fixed at the second extremity of wire 96, under
latch lever member 82. Since hook springs 66 tend to keep
hook member 58 in its hooking position, wire 96 will pull
on retainer cap 100 and contribute to keep latch lever
member 82 in its latched position. When hook member 58
pivots into its unhooking position (figure 7), since link
80 keeps latch lever member 82 in its latched position,
wire 96 will be free to move downwardly under the (less
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than considerable) weight of retainer cap 100.
- However, if latch handle 72 is pivoted
downwardly, latch lever member 82 will be free to move from
its latched position to its unlatched position. When the
piston rod 52a of corresponding ram 52 is retracte (as ~.~e
right hand ram 52 of figure 2), there is no tension in
spring 86 and hook member 58 will be kept in its hooking
pose ion , ~ ~1 e-~?-6 ___ .. . __
latch lever member 82 into its latched position. When
piston rod 52a is gradually extracted,-hookwmember 58 moves
upwardly and piston 90 will slide correspondingly upwards
in piston guide 92, until its lower end equipped with a
radial flange 90a abuts against piston guide 92, near the
one third of the course of piston rod 52a. For the rest of
the piston rod extraction, spring 86 will be gradually
stretched and it will apply a downward force on latch lever
member 82, thus applying a pressure to pivot hook member 58
into its unhooking position through the instrumentality of
wire 96.
Therefore, when latch handle 72 is kept in its
upwardly oriented position, springs 86 have no effect
whatsoever. But when latch handle 72 is pivoted
downwardly, hook member 58 will be pivoted into its
unhooking position unless it already engages a rung 45
which would prevent this. Indeed, figure 9 shows that the
retaining surface 101 (by abutting on rung 45) of hook
member 58 prevents the latter from pivoting to its
unhooking position. Thus, when the operator desires work
platform 48 to move downwardly, he pivots both latch
handles 72, 72 downwardly and he positions control handle
68 to its platform lowering mode. When a ram 52 engages
with its hook member 58 a rung 45, the hook member 58 of
the other ram 52 still engages the next upper rung 45 and,
an instant later, as this second ram 52 extracts its piston
rod 52a even more, hook member 58 vertically clears this
rung 45 and is free to pivot to its unhooking position
under the action of corresponding springs 86, 86. Ram 52
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is then free to proceed to the retraction of its piston
rod, since hook member 58 will then not hinder its downward
movement because hook member 58 is in its unhooking
position which clears rungs 45. When spring 86 ceases to
apply tension because it is unextended (near the one third
of its course and after clearing two consecutive rungs 45),
hook member 58 regains its hooking position under the bias
o springs we ~.... _._~e___..__..__._.
downward movement of work platform 48 is therefore
accomplished without the constant -intervention of the
operator.
To move work platform 48 upwards, the operator
must pivot both latch handles 72 into their upwardly
oriented position (figure 10) and position control handle
68 in its platform raising mode.
Figure 2 shows that vertical beams 94 hold a gear
housing 102. Figure 15 shows that gear housing 102 houses
two slidable toothed racks 104, 104, which are fixedly
attached (e.g. welded) by means of a rack plate 106 to a
corresponding hook bolt 59, and a complementary gear wheel
108. Rack plates 106 have a generally triangular shape and
have flanges 106a extending along racks 104 to allow
bolting of one to the other. Housing 102 has openings on
its sides to allow rack plates 106 to extend outwardly
therefrom (figure 16).
The racks 104 and gear wheel 108 assembly
synchronizes the relative movement of hook members 58, 58
to prevent them from being unattuned with one another,
which would of course mean that the platform raising system
50 would be inoperable. Both hook members 58 therefore
always stay in registration with one another.
Figures 17 to 20 show a security braking system
110 installed between the two vertical beams 94 of sleeve
member 46 (figure 2). Braking system 110 comprises a
rocking member 112 which can pivot around a holding pin 114
between a rung clearing position (figure 17) and a rung
engaging position (figure 19). Rocking member 112 has a
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13a
sectorial edge 115 and a blocking arm 116 having a T-shaped
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cross-section at its free extremity 116a (figure 20) and
extending opposite sectorial edge 115 on rocking member
112, T-shaped extremity 116a being a counterweight for the
rest of rocking member 112. A concentric arcuate slot 118
is provided near sectorial edge 115 through which a
blocking pin 120 is slidable. The rung engaging and rung
clearing positions are defined by the corresponding limit
positions of rocking member 112 sliding around blocking pin
120 between the two positions in which the extremities of
arcuate slot 118 abuts against blocking pin 120.
Braking system 110 further comprises a retainer
arm 122 positioned over rocking arm 112 and pivotable
around an arm pin 124. Retainer arm 122 has a wheel 126
near arm pin 124 which engages a complementary widthwise
groove 128 in rocking member 112 when it is in the rung
clearing position. A finger 130 is pivotably installed on
retainer arm 122 generally opposite wheel 126 relative to
arm pin 124, a finger spring 132 also linking it to
retainer arm 122.
A tension spring 134 is hooked to a hook 135
protruding from sectorial edge 115 of rocking member 112 at
its first extremity and to a spring pin 136 fixed to
vertical beams 94, 94 at its second extremity. Tension
spring 134 is stretched when rocking member 112 is in its
rung clearing position, and lengthwisely paritally bears on
sectorial edge 115 of rocking member 112.
In use, finger spring 132 is in its equilibrium
state when finger 130 is between two rungs 45 (ffigure 17 in
full lines), the free extremity of finger 130 then
extending beyond the vertical plane of rungs 45 shown in
figures 17 to 19 by axis 138: finger 130 is then in its
rung engaging position. When sleeve member 46 is lowered
at a normal (relatively slow) rate, finger 130 will hit
smoothly each successive rung 45 and pivot upwardly until
rung 45 is cleared (figure 17 in dotted lines). Finger
spring 132 will pivot finger 130 back into its rung
engaging position afterwards. When sleeve member 46 is
CA 02288162 1999-10-29
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raised, finger 130 will hit smoothly each successive rung
45 and pivot downwardly until rung 45 is cleared (figure 17
in dottes lines). Again, finger spring 132 will pivot
finger 130 back in its rung engaging position afterwards.
5 If sleeve member 46 was to descend a~riormalTy
fast (i.e. falling) as suggested in figures 18 and 19,
finger 130 would hit the next rung 45 at high speed,
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backwards suddenly. The force of this sudden backward
10 movement would be transmitted to retaineY arm 130 which
would in turn pivot counterclockwisely as suggested in
figures 18 and 19 causing wheel 126 to escape from groove
128 and allow rotation of rocking arm 112 around holding
pin 114. Tension spring 136 would then pivot rocking arm .
15 112, as suggested with an arrow in figure 18, from its rung
clearing position until the latter reaches its rung
engaging position (figure 19). Once wheel 126 disengages
groove 128, the inertia of counterweight free extremity
116a of blocking arm 116 will also contribute to pivot
rocking arm 112.
When the next rung 45 is encountered, bloc:{ing
arm 116, now in the rung engaging position and therefore
extending beyond plane 138, will abut against this rung 45
(figuer 19) and stop the fall of sleeve member 46.
Figure 21 shows the hydraulic circuit 140 of
platform raising system 50. There is provided a motor 142
(internal combustion or otherwise) linked to a pump 144
which feeds circuit 140 with the proper fluid (e.g. oil)
from a supply reservoir 146. The fluid will be fed
simultaneously to each ram 52, but the hydraulic flow input
will be fed alternately to the upper and lower circuit
connections 52b and 52c, respectively, of rams 52, which
will result, as is known in the art, in the alternate
movement of the piston rods 52a of rams 52. A flow
controler 148 will determine, through the instrumentality
of control handle 68 (figure 22), the direction of the
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flow, which in turn will determine wether the sleeve member
is raised or lowered.
A basic form of sleeve member 46 is shown in '
figure 23. This sleeve member has a central sleeve 150 and
one generally cubic side structure 152 on each side of
central sleeve 150. Each side structure 152 has a
plurality of joists and cross bars, as is detailed in the
previously cited patents. Under each side structure 152
are fixedly attached rectangular tubes 153 for slidably
inserting complementary rectangular support rods (not
shown). On these support rods a platform can be removably
installed for supporting workmen. A second and a third
platform (not shown) can also be installed on sleeve member
46, on the top bars 154 of side structures 152, for
supporting equipment used by the workmen at a height that
would be easily reachable without having to bend down.
To the basic sleeve member 46 can be added a
plurality of strucural module members 156 (figures 24 to
26) that are similar to the cubic side structures 152, 152.
Figures 23 to 26 show that these module members can be
removably installed on the outer end of side structures
152, 152 by means of hooking members 158 slidably
engageable into complementary hook casings 160. Any number
of these module members 156 can be added to the basic
sleeve member 46 (up to the structural capacity limit of
the material being used, of course) since every module
member 156 is equipped with hooking members 158 on one side
and with hook casings 160 on the other.
It is understood that sleeve member 46 and all
module members 156 attached thereto must be of
approximately equally distributed weight and approximately
symmetrically installed relative to tower 40, so as to be
generally balanced and not induce important stresses in
tower 40 due to lateral tilting of the latter.
Figure 27 shows the tower 40 and sleeve member 46
engagement. It can be seen in figures 27 to 29 that idle
rollers 162 are installed on the inner side of sleeve
CA 02288162 1999-10-29
WO 98/50301 PCT/CA97/00307
- 17 -
member 46 to rotatably abut against the outer side of tower
40 on its corner tower posts 163 to prevent sleeve member
46 from moving in any direction except along tower 40.
Figures 29 to 31 show that tower 40 is modular.
Indeed, attachment means 164 are provided to fixedly attach
two tower modules 166 to one another. With this modular
tower 40, the height of the tower can be easily adjusted by
the workmen. Attachment means 164 can be, for example, of
the type shown in f figures 3 0 and 31, comprising a s 1 ider
plate 168 slidably engaging a pair of parallel receiving
plates 170, 170 and fixed thereto by means of a bolt 172.
