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.

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.

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.