U.S. patent number 3,745,935 [Application Number 05/244,648] was granted by the patent office on 1973-07-17 for foldable table.
Invention is credited to James Bruce Douglas.
United States Patent |
3,745,935 |
Douglas |
July 17, 1973 |
FOLDABLE TABLE
Abstract
A foldable drafting table having front and rear legs pivotally
connected together and a drawing board pivotally connected to the
legs, and also including adjustable spacing means interconnecting
the legs and the board for holding the board in a variety of
sloping positions, and in which the adjustable spacing means is
demountable to allow folding of the board flat against the legs.
The leg assemblies at opposite sides of the board are preferably
pivotally mounted with respect to each other, to allow the table to
stand steadily on an eneven floor, and the leg assemblies are
preferably interconnected by a shaft which allows such pivotal
movement but which resists side sway of the legs. The adjustable
spacing means is preferably a telescopic arrangement of inner and
outer tubes having clutch means such as are described in Canadian
Pat. application No. 109,344 filed April 1, 1971.
Inventors: |
Douglas; James Bruce (Montreal
252, Quebec, CA) |
Family
ID: |
4092168 |
Appl.
No.: |
05/244,648 |
Filed: |
April 17, 1972 |
Foreign Application Priority Data
Current U.S.
Class: |
108/1; 108/5;
108/9; 108/145 |
Current CPC
Class: |
A47B
27/02 (20130101); A47B 2003/008 (20130101) |
Current International
Class: |
A47B
27/00 (20060101); A47B 27/02 (20060101); A47f
005/12 () |
Field of
Search: |
;108/1-10,137-145 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Zugel; Francis K.
Assistant Examiner: Finch; Glenn O.
Claims
I claim:
1. A foldable table comprising:
a. two spaced apart leg assemblies, one for each side of the table,
each assembly including a front and a rear leg, the legs being
pivotally connected together for relative movement between a
splayed apart operative condition and a substantially flat folded
condition,
b. board means pivotally connected to said leg assemblies for
move-means between a variety of sloping operative positions and a
folded condition in which the board means is flat against the leg
means when in their folded condition,
c. shaft means extending perpendicularly to said leg assemblies, at
least one of said assemblies being mounted on the shaft means by
means allowing angular movement of the leg assemblies about the
axis of the shaft means while restraining angular movement of the
leg assemblies about axes perpendicular to the shaft means whereby
the relative angular positions of the leg assemblies about the axis
of the shaft means may be adjusted to allow the table to remain
steady on an uneven floor while side sway is restrained,
d. individual adjustable spacing means each interconnecting one
side of the board means with the adjacent leg assembly, said
adjustable spacing means being steplessly adjustable in length and
also being demountable to allow the board means to be folded
against the leg assemblies, and
e. a common operating means for simultaneously releasing the two
adjustable spacing means to allow adjustment of the board means or
relative angular movement between the two leg assemblies.
2. A table according to claim 1, wherein said adjustable spacing
means each include an inner member movable within an outer member,
said spacing means being demountable by removal of the inner member
from the outer member.
3. A table according to claim 1, wherein said adjustable spacing
means each include an inner member movable within an outer member,
and a resilient compressible element of rubber-like material having
side walls contactable with the inner walls of said outer member
and having opposite ends held by two pressure members movable with
the inner member, said pressure members being also movable relative
to each other to apply pressure to said element in such manner as
to deform the element and to press the sidewalls thereof against
the inner walls of the outer member, and wherein said operating
means is linked to one of said pressure members of each spacing
means for controlling the deformation of said element, said
operating means being movable from a position in which the
compressible element is relatively undeformed and allows relatively
free sliding of the members to a position in which free sliding is
prevented so that the adjustable means supports the board means,
said adjustable means being demountable by removal of said inner
member from said outer member.
4. A table according to claim 1, wherein each of said leg
assemblies has a transverse bore which receives an end of said
shaft means, and wherein a slit is provided in each leg assembly
parallel to and communicating with said bore, said slit being
provided with clamping means effective to cause partial closure of
said slit and thereby to cause frictional engagement between the
leg assembly and the shaft means to prevent slackness of the leg
assembly on the shaft.
5. A table according to claim 1, wherein said adjustable spacing
means includes, for each side of the table, a first spacing means
interconnecting one of said leg assemblies and a member pivotal at
one end about the upper end of said one leg assembly, the other end
of said pivotal member carrying the board means pivotally mounted
thereon, said adjustable spacing means further including a second
spacing means interconnecting the said pivotal member and the board
means, whereby adjustment of said first and second adjustable
spacing means gives adjustment of both the height and the angle of
slope of the board means.
6. A foldable table according to claim 3, wherein said operating
means comprises a rod extending across the board means and passing
through said inner members of both said spacing means, and said rod
being rotatable by handle means, and said rod carrying cam means
linked to one of said pressure members of each said spacing means
whereby rotation of said rod by said handle controls the
deformation of the compressible elements of both the spacing
means.
7. A foldable table according to claim 1, wherein said board means
includes angle members extending fore-and-aft of the board means
and each having a depending flange pivoted to one of said leg
assemblies, and wherein said depending flanges are rigidly
connected by a bar which resists warping of the board means.
Description
The present invention relates to tables having a tilting top, for
example drafting tables, and in particular to an inexpensive
folding drafting table having board means adjustable to a variety
of sloping positions. The drafting table is preferably
foldable.
A table in accordance with one aspect of the invention comprises
leg means including front and rear legs pivotally connected
together for relative movement between a splayed apart operative
position and a substantially flat folded condition, and board means
pivotally connected to the leg means for movement between a variety
of sloping operative positions and a folded condition in which the
board means is flat against the leg means when in their folded
condition. Adjustable spacing means, which are preferably
telescopic, are also provided interconnecting the leg means and the
board means for holding the board means in its sloping positions,
and the adjustable spacing means are demountable to allow folding
of the board means flat adjacent to the leg means.
The table preferably has two spaced apart leg assemblies, one for
each side of the table, each assembly comprising a front and a rear
leg pivotally connected at their upper ends for relative movement
between a splayed apart operative position and a substantially flat
folded condition. Two adjustable spacing means are provided each
interconnecting a leg of one of said leg assemblies to the adjacent
side of the board means.
The preferred form of the table in accordance with the invention
has a special self-levelling leg arrangement which allows the table
to remain steady even when placed on an uneven floor. In accordance
with this aspect of the invention, in a table including two spaced
apart leg assemblies one for each side of the table, the upper ends
of each of the leg assemblies are interconnected by a shaft
extending perpendicularly to the leg assemblies, at least one of
the assemblies being mounted on the shaft by means allowing angular
movement about the axis of the shaft while restraining angular
movement of the leg assemblies about axes perpendicular to the
shaft, whereby the relative angular positions of the leg assemblies
may be adjusted to suit the legs to an uneven floor, while side
sway of the leg assemblies is restrained.
The telescopic spacing means are connected between pivots on the
board means and the leg means, clutch means being provided to hold
the telescopic parts of the spacing means in different relative
positions. Telescopic spacing means of this type may be demountable
by sliding an inner telescopic member out of the end of an outer
member.
Where the table in accordance with the invention has the
self-levelling leg assemblies, and also has, as is preferred, an
adjustable spacing means at each side of the board means associated
with each of the leg assemblies, the adjustable spacing means must
allow infinite adjustment of the spacing between the board means
and the part of the leg assembly to which the spacing means is
connected, so that slight rotation of one leg assembly relative to
the other does not cause warping of the board means. Any such
warping is minimized by the special board construction to be
described. A particularly suitable and convenient form of
adjustable spacing means of the telescopic type which is both
demountable and which allows for infinite adjustment of its length
within a certain range is telescopic means including a telescopic
arrangement of an inner and an outer member, and a clutch mechanism
allowing the members to be held in different relative positions,
the clutch mechanism including a resilient compressible element of
rubber-like material having side walls contactable with the inner
walls of the outer member and having opposite ends held by two
pressure members movable with the inner member. The pressure
members are also movable relative to each other to apply pressure
to the compressible element in such manner as to deform the element
and to press its side walls against the inner walls of the outer
member, and operating means is linked to one of the pressure
members for controlling the pressure applied to the element. The
operating means is movable from a position in which the
compressible element is relatively undeformed and allows relatively
free sliding of the telescopic members, to a position in which free
sliding is prevented so that the adjustable telescopic spacing
means can support an article such as the board means. This type of
telescopic adjustable means is demountable by removal of the inner
member from the outer member.
The invention will now be described by way of example with
reference to the accompanying drawings, in which:
FIG. 1 shows a perspective view of a first embodiment of drafting
table,
FIG. 2 shows a front elevation of the same drafting table,
FIG. 3 shows a detail side view of the upper parts of the legs at
the right hand side of the table and their connection to the board
means, and a part of the board means,
FIG. 4 shows a detail frontal view of similar parts,
FIG. 5 shows an enlarged cross-sectional view of the adjustable
spacing means, taken on line 5--5 of FIG. 2,
FIG. 6 shows a perspective view of the drafting table when folded,
and
FIG. 7 shows a side view of a second embodiment of drafting
table.
Referring to FIG. 1 of the drawings, the folding drafting table 10
includes, as its main components, leg means including two laterally
spaced apart leg assemblies 11 and 12, one for each side of the
table, board means 14 having brackets 15 pivotally connected to the
upper ends of the leg assemblies, and adjustable telescopic spacing
means 16 connected between pivots carried by the leg means and the
board means and adjustable to hold the board means in a variety of
sloping positions.
The leg assembly at each side of the table includes a short front
leg 20, carrying at its upper end a bracket 21, to which is
pivotally connected by bolt 22 a rear leg 23. The rear leg 23 is
longer than the front leg 20 and extends up beyond the bracket 21,
and the upper end of each rear leg 23 is pivotally connected by
bolt means 25 to vertical flange 27 of one of the brackets 15. The
bolts 22 connecting the brackets 21 to the legs 23, and the bolt
means 25 connecting the legs 23 to the brackets 15, have horizontal
axes parallel to the front of the table, such as to allow folding
of the leg means between the splayed apart position of FIG. 1 and
the folding position of FIG. 6. The bolts 25 also allow folding of
the board means between various sloping positions, such as are
useful in drafting, and a position in which the board means is flat
and adjacent to the legs as in FIG. 6. The front and rear legs may
be formed of one inch square 18 gauge steel tubing, and the lower
ends of the legs having anti-slip glides.
Each of the rear legs 23 is provided with a transverse bore near
its upper end just below the pivot bolt 25, and these bores receive
the ends of a shaft 30 which is in the form of a circular section
tube extending across the width of the table, perpendicular to the
leg assemblies, so as to interconnect these assemblies. The upper
ends of the rear legs are each provided with a slit 32 which is
parallel to the axis of the bore and which connects the bore with
the upper end of the leg, and nut and bolt means 33 are provided
transverse to the slit 32 and effective to cause partial closure of
the slit on tightening. The nut and bolt means 33 is tightened
sufficiently to cause frictional engagement between the transverse
bore of the leg means and the tube 30, so that there is no undue
slackness between tube 30 and the rear leg, although at the same
time the leg assemblies are able to pivot about the axis of tube 30
so that the legs can be adjusted to stand steadily on an uneven
surface. The inner-engagement of the transverse bore of each leg 23
with the tube 30 thus restrains side sway of the leg
assemblies.
The drawing board means 14 comprises a flat board 35 of Macrolite
(Trade Mark) fixed to the upper horizontal flanges of the brackets
15, which brackets are in the form of angle members extending fore
and aft of the board and which also act as stiffening means for the
board. An anti-warp torsion bar 36 extends across the width of the
board and has its ends securely welded to the central area of the
flanges 27 of the brackets 15. The torsion ba 36 is a one inch
square steel tube which is sufficiently resistent to torsional
deflection to prevent any substantial warping of the board 35. The
front edge of the board is provided with a ledge 38 for
pencils.
The adjustable telescopic spacing means 16 includes an inner upper
tube 40 slidable within a lower outer tube 41. The inner tube 40 is
mounted on a rod 43 which extends across the width of the board
means and which is rotatable in bores in the flanges 27, the rod 43
also passing through horizontal bores in the upper ends of the
inner tubes 40. Each of the outer tubes 41 is pivotally connected
to one of the rear legs 23 by means of a horizontal bolt 44, the
bolt passing through a horizontal bore in the end of tube 41 and
being provided with a nut to hold the tube in place.
The tubes 40 and 41 are holdable in a variety of relative positions
by clutch means particularly shown in FIG. 5. These clutch means,
include a resilient compressible element 46 of rubber-like material
of cylindrical form, and having side walls contactable with the
inner walls of the outer tube 41, and readily slidable therein when
uncompressed. The element 46 is about seven-eighths inch in
diameter. The upper and lower ends of the element 46 are held
between two pressure members consisting of a plate 48 which closes
the lower end of the inner tube 40, being welded thereto, and a
washer 49 held by lock nuts 50 on a screwed lower end of a rod 51.
The rod 51 passes up through a central bore in the element 46,
through an aperture in the plate 48 and upwardly inside the inner
tube 40 the upper end of the rod 51 being provided with a flat
plate 53 welded across its end. The rod 51 is urged upwardly by a
compression spring 54 acting between the plate 53 and a further
plate 55 welded across the inner tube 40. The spring 54 is strong
enough to compress the element 46 axially in such manner as to
force its side walls against the inner walls of tube 41 with
sufficient force that the element 46 becomes virtually locked
within the outer tube, holding the telescoping tubes in a
particular relative position.
The upper surface of plate 53 rests, in the position shown in FIG.
5, against the side of the rotatable rod 43. As shown, the rod 43
constitutes a part of operating means for the clutch means, and for
this purpose the portion of the rod 43 within the upper ends of the
tubes 40 at each side of the table is provided with a drilling
which carries a short lug 56. This lug projects a short distance
from the surface of the rod 43 and has a squared end. The rod 43 is
also provided with handle means in the form of a bent-over end
portion 58 on an extension of the rod 43 beyond the flange 27 of
the right hand side bracket 15, this bent-over end portion having
at its end a knob 59. In the position shown in FIG. 5, with the lug
56 horizontal, the end portion 58 of rod 43 is also horizontal,
i.e. the lug 56 and portion 58 are aligned. In this position, the
spring 54 is compressing the element 46 to its maximum extent so
that the sides of this element bind inside the tube 41 and
virtually prevent relative movement of tubes 40 and 41. The
bent-over end portion 58, which constitutes handle means, can be
moved downwardly to a vertical position below the board means, in
which it is aligned with the tube 40, and in this position the lug
56 will act in the manner of cam means against the plate 53 urging
this downwardly, and thus moving the washer 49 downwardly relative
to plate 48 and releasing the axial compression on the element 46,
allowing tube 40 to slide within the tube 41. The flat end of lug
56 tends to hold the handle means in this position until the handle
is positively moved away towards the position of FIG. 5. Since each
of the clutch means for the two telescopic adjustable spacing means
is identical, both of these are operated simultaneously by movement
of the single handle means 58.
It will be understood that references to the handle means as being
horizontal or vertical only strictly apply when the board means is
horizontal as shown in FIG. 5, and that the handle means operates
in accordance with its relative position to the axis of the tube
40.
With the front and rear legs of the leg assemblies in their splayed
apart condition, as shown in FIG. 1, and with the telescopic
spacing means mounted as shown in FIG. 1, the table is operative
for use as a drafting table. The angle of tilt of the board means
can be adjusted by moving the handle means 58 downwardly to cause
the lugs 56 of rod 43 to depress the plate 53, releasing the axial
compression on the elements 46 and thus allowing these to slide
within the tubes 41 while the board means is adjusted to a desired
sloping position. Release of the handle means to the position of
FIG. 5 allows the spring 54 to compress the elements 46, thus
effectively locking the clutch mechanism and holding the board
means in the particular position. If the table is being used on an
uneven floor, the leg assemblies can readily be slightly rotated
about the tube 30 to allow the four legs to contact the floor
properly and to hold the table steady. In fact, the bolt means 33
which adjust the frictional engagement of the rear legs 23 on the
tube 30 are adjusted so that the required amount of relative
rotation will occur when the table is simply set down firmly on the
floor.
It may be noted that the clutch means used for the telescoping
spacing means allows stepless adjustment of length within a
predetermined range. Thus, there is no problem caused by slight
rotation of one leg assembly relative to the other, and (provided
the clutch means are temporarily released), this does not cause
warping of the board means.
When it is required to store or transport the drafting table, the
table is folded by firstly demounting the telescopic spacing means,
and then folding the legs. To demount the spacing means, the handle
means 58 is placed in a position parallel to the axis of the tubes
40, in which condition the flat end of the lugs 56 are against the
respective plates 53 so that the handle means 58 tends to remain in
this position. The board means is then raised about its front
pivot, extending the telescoping tubes 40 and 41 to such an extent
that tube 40 comes out of the end of the tube 41. The tube 40 is
then folded in under the board means, and the tube 41 is folded to
the side of the rear legs, after which the board means is folded
flat adjacent to the rear legs, and the front legs are also folded
flat against the rear legs. The table is then in the flat folded
condition as shown in FIG. 6.
FIG. 7 shows a second embodiment which is similar in principle to
that of FIGS. 1 to 6, but which has additional means allowing the
board means not only to be tilted to any desired position, but also
raised to any desired height. As shown, the drafting table includes
leg assemblies identical to the first embodiment, except in that
the shorter leg 120 is now the rear leg, and the longer leg 123 is
now the front leg. The leg assemblies on each side of the table are
joined by a shaft 130 which performs a function similar to that of
shaft 30 in the first embodiment. The upper ends of the legs 123
instead of carrying the board means directly, carry two side
members 100 each pivotal at one end about the upper end of the
adjacent leg assembly, and the board means 114 are pivotally
mounted at 125 at the other end of the pivotal members 100. Two
sets of adjustable spacing means are provided, including a first
set 116a which interconnects the front legs 123 and the pivotal
members 100 to allow these pivotal members to be adjusted to a
variety of angular positions, and a second set of adjustable
spacing means 116b which interconnects the pitoval members 100 and
the board means 114 to allow the board means to be adjusted to a
variety of angular positions relative to the members 100. Each set
of adjustable spacing means is provided with operating means
including handles 158a and 158b accessible from one side of the
board means, the nature of the adjustable spacing means and the
operating means being the same as that described with reference to
FIGS. 1 to 6. By using the first set of adjusting means 116a, the
inclination of the members 100 is adjusted, and thereby the height
of the board means pivot 125 is also adjusted. The combined use of
both the adjustable spacing means 116a and 116b thus provides means
for both adjusting the height, and the angle of tilt of the board
means 114. The table shown in FIG. 7 may be folded flat by
demounting of the adjustable spacing means in the same manner as
for the adjustable spacing means of the first embodiment, and the
folding flat of the board means, the pivotal members 100, and the
legs.
* * * * *