Note: Descriptions are shown in the official language in which they were submitted.
2041990
TITLE OF THE INVENTION:
__________-------------
ADJUSTABLE LEGS FOR DESK AND THE LIKE
BACKGROUND OF THE INVENTION:
_____----------------------- :
Field of the invention:
The present invention relates to school desks and
chairs adjustable in height and in particular to legs for desk
which can vary in length.
Furniture for primary schools requires
considerable storage space because the pupils and students using
them do not have, year after year, the same stature.
Furthermore, the same school may have different repartition of
pupils among the different grades.
It is an object of the invention to change the ~
height of desks and chairs so that a minimal number of such -
pieces of furniture be needed to accommodate a plurality of the -
corresponding numbers of students regardless of their height.
It is another object of this invention to adapt
existing equipment to meet the requirements of adjustablility.
The present invention can be implemented by cutting the legs of
presently available desks and chairs and providing suitable
extentions for them.
Prior art: ~ -
~''-'' -"
The search performed by the applicants has
revealed two Canadian patents directed to means for adjusting the -~
height of school desks. In Canadian patent No. 739,251, a pair
::, .
2041990 :
--2--
o~ telescopic tubes is described with a displacing means
consisting of a combination of a toothed rack and ratched wheel ,
mounted on the tubes to adjust the height of the desk and to lock
the tubes in a fixed position.
In Canadian patent No. 764,304 the school desk is -
vertically adjustable. The legs of the desk consist of two
coaxial tubes which are vertically adjustable by means of a screw
spindle and a pair of bevelled pinions fixed at the upper end of
the screw spindle. ~
The prior art discloses complex mechanical ~ ;
arrangements which are expensive and do not allow the conversion -
of conventional wooden desks into desks having adjustable ~
heights. ,-
SUMMARY OF THE INVENTION~
The adjustable desk according to the present
. . .
invention makes use of a rectangular cross sectional leg having a
relatively short height and a sleeve member having four lateral
walls forming an internal cross-section substantially
corresponding to the cross-section of the leg for allowing the
sleeve member to fittingly slide over the leg. The sleeve member
is provided with a set of vertically spaced holes in
diametrically opposed walls which are selectively aligned with a
perforation extending perpendicularly across the leg at a
location adjacent the lower end thereof. A screw and nut
combination adapted to fittingly slide through both the
`` 2~199~ :
perforation and the holes longitudinally locks the sleeve and the
leg while applying pressure on the walls of the sleeve member ;~
over the leg.
The sleeve member is particularly adapted to
easily slide over the leg by providing at least two longitudinal
ribs on the inner surface of each of the walls for allowing a
better sliding control of the sleeve member over the leg.
The screw and nut combination is preferably
mounted through a central vertical axis of the leg between two
internal ribs to provide a more positive locking action of the
screw and nut combination.
'-
Considering that the sleeve may be long and that
~;~ the legs may be extended up to a relatively important height, the
legs are fixed to the frame of the desk with a bracket adapted to ~;
solidify the leg to the deæk per se.
BRIEF DESCRIPTION OF THE DRAWINGS: ~ -
; Figure 1 is a perspective view of a desk according
to the present invention, ! ` '',' '''~'
Figure 2 is an exploded view of a tubular member
,-:.- ~-:,: :'
adapted to be mounted on a leg and locked by a screw and nut ~ ~
combination, -
Figure 3 illustrates a perspective view of a screw
and nut combination suitable for locking the tubular member over
the leg, ; ;
; '. '...':.' ':
~:`` 2 0 ~
-4-
Figure 4 is a perspective view of a tubular member -
provided with a set of vertically disposed holes and a resting
plate for contacting the ground, and ~ ~
Figure 5 is a bottom view of a corner of the desk ~;
illustrating a particular means for fixing the leg.~ `
' ,,
DETAILED_DESCRIPTION OF_THE_INVENTION ., :~'
Figure 1 illustrates a desk lO having four legs
12, each leg being supported by a tubular member 14. The tubular
member 14 is locked to the leg 12 by a screw and nut combination
16 which maintains the bottom 18 of the leg 12 above the ground.
The height of the top surface 20 of the desk can be adjusted by ;~
selective]y positioning the bottom of the leg 18 at a different
level in the tubular members 14.
: .'' ',' ~;
Figure 2 illustrates a preferred embodiment of the
invention, The leg 12 which is provided with a perforation
across the center of the cross-section of the leg 12 is located
at a distance adjacent its lower end 24 and generally at a
distance of about three inches.
, Although thè internal cross-section of the' tubular
member 14 corresponds to the outer cross-sectional dimension of
the leg 12, for slidingly fitting over the latter, in the
embodiment shown in figure 2, the tubular member 26 which has
four lateral walls 28, 30, 32 and 34 is provided with ribs 28a
and 28b on wall 28, ribs 30a and 30b on wall 30, ribs 32a and 32b
on wall 32 and ribs 34a and 34b on wall 34. The inner surface of
--~ 204i99~
-5-
the ribs forms a contour which corresponds to the outer contour
of the leg 12 to allow a smooth sliding operation of the leg 12
inside the tubular member 26. All the ribs have preferably a
flat surface facing the leg 12 for maintaining a more positive
contact with the leg 12. Ribs having a thickness of about .1 to
.2 inches i9 sufficient for legs of about 2 inches square.
The ribs on each wall are preferably set by pairs
equally spaced on each side of the vertical central line of each
wall. This disposition ;s particularly preferred for their
relation with the holes such as 38 and 40 which are vertically
aligned midway between the two ribs 34a and 34b. This
disposition also applies to the holes such as 44 and 46 located
through the wall 30 diametrically opposed to the wall 34. The
hole 44 is horizontally aligned with the hole 38 as well as hole
46 which is aligned horizontally with holes 40. Each of the
holes on wall 34 has a corresponding hole through the wall 30.
~; ~ When the sleeve 26 is mounted over the leg 12 and
holes 40 and 46 are aligned with the perforation 22 in the leg
12, the screw 46 is introduced in a hole 38 and the perforation
22 ,and the nut 48 is introduced in the hole 44 and the
perforation 22 and are treadedly engaged to each other. The
screw 46 is provided with a head 50 and the nut 48 is provided
with a head 50 so that the tightening of the screw in the nut
will provide a pressure on the walls 34 and 30 towards the leg
12. This pressure is located between the ribs 30a and 30b and
between the ribs 34a and 34b so that a slight concave effect is
' .-, . ..
2 0 ~
produced on the walls 30 and 34 for providing an additional and
more positive locking effect between the tubular member 26 and
the leg 12.
The legs 12 are generally made of wood and the
sleeve members such as 26 are preferably made of plastic such as
polyethylene of high density which is wear-resistant and provides
a low coefficient of friction for its contsct with leg 12. The
type of screw and nut used is illustrated in figure 3. The screw
has a threaded portion 52 which is partly covered by a
plastic sleeve 54 having a diameter corresponding to the internal
diameter of the holes such as 38 and perforation 12. The nut 56
has an internally threaded shaft 58 which also have an outer
contour corresponding the inner contour of the hole 44 and the
perforation 22. The diameter of the plastic sleeve 54 and the
shaft 58 prevents the leg from vibrating inside the tubular
sleeve 26. The screw 50 has a head 60 similar to the head 62
provided for the nut 56 for applying an internally directed
pressure on the walls of the tubular sleeves as explained above.
A slot is additionally provided in the head 60 as well as in the
head 62 (not shown) for facilitating the tightening of the screw
,:, , ~ ,
50 in the nut 56. ~. '
Figure 4 shows an embodiment of the tubular sleeve
14 which is provided with a footing member 66. A portion of the
footing member 66 has a contour so as to be fittingly secured -- :~
inside the leg 14 while the portion 70 exceeds laterally under
the walls of the leg for providing a more widely dispersed
~ ~.
; ~-
20~1990
.
pressure over the ground supporting a desk and in particular leg .
14.
Cons;dering that the legs 12 are provided with
extensions which provides additional leverage action on the legs
relative to the desk, the leg 70 such as shown in figure 5 is :
connected to the lateral skirt members 72 and 74 pending under ~:~
the top surface 20 by a bracket 76 forming a right angle portion ~ .
78 adapted to contact two internally facing ]ateral sides of the .
leg 70 and two flanges 80 and 82 laterally contacting the inner
surface of the skirt members 72 and 74. The bracket 76 is fixed ~
to the leg 70 and the skirt members 72 and 74 with screws 84. -.
The bracket 76 is preferably made of rigid metal.
~", ,"~
,.,~
` ~ .. "''.,,.~,i',.
~ ..; . . . .
~i`l
,, . -,-, .
