Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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"Improvements in or relating
_ to builders scaffolding"
This invention relates generally to builders
scaFfolding for access or propping purposes and of the kind
comprising upright supports or standards, longitudinally
Pxtendin-g bearsrs nr led~ers and transversely ex-tendirlg
bearers or transoms all of which are connected together to
form a rigid structure.
The presenL invention is concerned with a base jaok
device for use with the standards of such scaffolding.
A number of different forms of base jack devices for
scaffolding are known but each of these known device~ has
one or more disadvar,tages. Thus, one such device comprises
a tube having a plurality of spaced pairs oF transver~e
hDles, a support bracket slidably mounted on the tube, and
a locking pin which is passed through a pair of transverse ;
: holes in the bracket, and through one oF said pairs o~
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~ : transverse holes in the tube, in order to selectively
:~ position the bracket on the tube. The tube also has, at
: 20 its lower end, a screw-thread which co-aets with a threaded
spindle fixed to a transverse base plate. In practice~
: the pairs of holes in the tube provide coarse heightwise
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: ~ adjustment of the bracket and the threaded spindle
provides fine heightwise adjustment of the bracket. The
main disadvantage of this device is that it is not
- practical LO limit the extent of the movement of the tube
on the threaded spindle and therefore, in using the device,
the scafrold builder cannot ascertain the extent of overlap ~;
between the tube and the threaded spindle. The r2sult of
.this is that the overlap could be as llttle as ane ar t.wo
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thre~d ~onvolutjc)n-l Ind this coul~ ~e~io~ly ~l~aken ~he
strength o~ the dev.ice, and also the stability of the
scaFFold struoture. F~Jrthel~more, in this device the
length oF the scre~/ thread of the spindle, and the spacing
o~ the tran~ver~e holes in th~ t~be must bD arranged so as
to provide ~ull adjustment throughout the length of the
tube. In determining the hole spacing and ~he thread
length factors, one has the choice a short thread length
and correspondingly closely spaced holesj or of a
relatively long thread length with more widely spaced
holes. The disadvantages of -this are that, in the former
case, the large number of holes dscreases the strength of
the tube and, in the latter case, the cost of ~he device
is increased oecause oF the increased length of thread.
15A further known device comprises a tube having a
transverse base plate and a plurality oF spaces pairs of
transverse holes7 an ex-ternally screw-threaded sleeve ~:
slidably mounted on the tube, a threaded nut in screw
engagement with the sleeve, and a locking pin co-acting
with the sleeve and the tr~nsverse holes in the tube to
seleetively position the sleeve on the tube. In this
device also the disadvantages regarding the hole spacing
and thread length factors arise. Furthermore, in thi~
device, the sleeve does not have holes to receive the
locking pin and merely rests on the locking pln. However,
in order to prevent relative rotation ~etween the sleeve
and the locking pin, semi-circular recesses are cut into
the end of the sleeve which means that the load of the
scaffold structure is supported by a part of the sleeve
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~/hich is conside~ably ~leclkened by the provision of the
scre~l thread. In addition, in this device, no means is
provided to prevent or avoid the threaded nut from being
un~crewed from the threaded sleeve.
It is among the objects o~ the present invention to
overcome, or substantially reduce, the disadvantages of
the known base jack devices.
According to the present invention, there is provided
a base jack device for builders scaffolding which comprises
an upright tube having a transverse base plate and a
plurality o~ spaced pairs of transverse holes, a
supporting sleeve assembly slidably mounted on the tube,
and a locking pin for selectively positioning the sleeve
assembly on the tube relative to the holes in the tube,
wherein the sleeve assembly is formed with a pair oF
oppositely disposed holes and, in the lowermost edg0
thereof, with a pair of oppositely disposed recesses so
that, in use, the locking pin can be used selectively
with the holes in the assembly or with the recesses of
th~ assembly.
More specifically, there is provided a bas~ jack
device for builders scaffolding which comprises an upright
s ,s.
tube having a transverse base plate and a plurality of
spaced pairs of transverse holes, a first sleeve slidably
mounted on thc tube and having, externally thereo~, a plain
portion and a screw-threaded portion, a second ~leeve
having an internally screw-threade`d portion in engagement
with the screw-threaded portion of the First sleeve, and a
locking pin for selectively positioning the first and second
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slePves on tl~e tube re:Lative to tlle holes in the tube,
wherein the plai.n portion oF the first sleeve is formed
with a pair of oppositely ~.isposed holes and, in the
lowermost edge of the sleeve, with a pai.r of oppositely
disposed recesses so that, in use, the locking pin oan be
used selectively with the holes in the sleeve Dr with -the
recesses of the sleeve.
According to another aspect of tile present invention,
tha second sleeve is formed with a longitudinally
extending slot to permit observation oF, and access to, at
least the uppermost end of the threaded portion of the
first sleeve.
The invention is illustrated by way of example in the ~.
accompanying drawings in which,
Figure 1 is an elevation of a base jack device
according to the invention,
: Figure 2 is an elevation in the direction of the arrow "X" of Figure 1,
Figure 3 is an elevation, on an enlarged scale, of
the first sleeve,
~: Figure 4 is an end eleva-tion in the direction of the
arrows C-C of Figure 3,
Figure 5 is an elevation, on an enlarged scale, of
the second ~leeve,
: 25 Figure 6 is a section on the line A-A of Figure 5,
and
Figure 7 is an elevation in the direction of the
arrows B-B of Figure 5.
~eferring to the drawings, there is shown a base jack
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for buil~r~ ~caf~o:Ld:ing which cornprise~ an upright. tube
1 having fixecl thereto, at its lower end, a transverse
base plate 2. The tube 1 is also formed with a plu~ality
of pa.irs of spaced oppositely disposed transverse holes 3.
Slidably mounted on the tube 1 is a support assembly
4 comprising a firs~ sleeve 5 formed, externally thereof,
with a plain portion 6 and a screw-threaded portion 7, the
plain portion 6 being lowermost with respect to the
up~ight tube 1. A second sleeve 8 in the form of a
ferrule having a reduced diameter internally-threaded
collar portion 9 is provided to co-act with the threaded
portion 7 of the First sleeve 5 At its ùppermost ehd~
the sleeve 8 is provided with an annular bearing plate
10 on which, during use, the lower end of a scafFold
standard indicated at 11 is supported.
The first sleeve 5 is also formed, in the plain
portion 6 thereof, wlth a pair o~ oppositely disposed
holes 12 and, in the lowermost edge of the sleeve, with a
~:: pair u~ oppositely disposad recesses 13 which provide two ..
alternative positions for a locking pln 14 and also serve~
:~ in use, to prevent relative ro~ation between the sleeve 5
and the tube 1. ~Tha locking pin 14 is attached, via a
flexible lead 155 to a lug 16 welded to the sleeve 5.
The locking pin 14 is also provided to co-act with
the holes ~ of the tube 1 as can he seen from Figures 1 and
2 of the drawings. Thus, it will be seen that, by
selectively positioning the p.in 14 in any one of the
~ pairs of holes 3 coarse heightwise adjustment of tha
bearing plate 10 is provided and 5 by turning the second
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slec!ve ~, using a tommy bar inserted in an apertured lug
17, relative to the first sleeve 5, Fine heightwise
adjustment of thc oearing plate 10 is provided~ In addition,
by providing the pair of holes 12, and the pair of
recesses 13, in ~he ~il`St sleeve 5, further and
intermediate coarse adjustment is provided.
The vertical spacing between the holes 12 and the
recesses 13 is half of that between the pairs of holes
in the tube 1 and therefore the number of pairs of holes
3, and the length of the threaded portion 7 oF the sleeve
5, can be reduced by half as compared with the prior art
arrangements. This clearly provides a tube 1 of gre-ater
strength and decreases the cost o~ the device in that it
decreases the length of thread required.
In use, in order to construct a scaf~old structure, a
base jack device is provided for each standard and the
haight of the bearing plate 10 is adJusted, by selectively
positioning the locking pin 14 in one of the pairs of holes
3, and in either the pair of holes 12 or the recesses 13,
.
so that all the bea-ring plates are roughly level with
each other. The structure is then partially built and is
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finally levelled by turning the second sleeves 8 of the
base jacks as hereinbefore described. The structure can
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; then be completed on the level base so formed.
In order to observe the position of the threaded
collar portion 9 of the sleeve 8 relative ta the
uppermost end oF the threaded portion 7 of the sleeve 5,
the sleeve 8 has formed therein a longitudinally extending
slot 18. Thus, the scaffold builder is able to ensure,
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before using the jack device that the secor)d sleeve 8 is
properly posi.tioned relat:ive to the First ~leeve 5. I~,
on the other hand, .it is required to make prov.ision to
ensure that th~ second sleeve is not removed from the
S first sleeve, the slot 1~ provides access to the threaded
portion 7 so that the thread can be upset, or so that a
weld spot 19 may be applied to the thread.
Thus, it ~j.ll be appreciated that the bass jack device
of the present invention has the advantages that it has an
increased height adjustabili.ty far~tor over known devices
and, by virtue of the fact that the locking pin 14 is not
directly associated with a screw-threaded part of the
supporting assembly, and the fact that ~he number of pairs
of holes 3 in the tube 1 are at a minimum~ it has
increased load.ing capabilities and is less expensive to
- produce. Furthermore a the present device has the
advantageous facility for ensuring that the -fine
adjustment means are not placed in a dangerous, or
critical, condition.
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