WO2023128776A1 - Retractable bed with mechanical system for adjustable height - Google Patents

Abstract

The invention refers to a retractable bed with a mechanical system for variable height that can be placed anywhere in a room. It consists of a bed frame, A, and a resistance and driving mechanical system made of two identical assembled columns, B, each of which comprise a resistance column, 25, outlaid parallelly at a convenient distance from one another (approximately the width of a bed), on whose upper heads an assembled beam, D, is fastened, on which an electromotor, 1, is mounted, which, through the agency of a belt, 2, simultaneously actuates two threaded assemblies, E, mounted in each resistance column, 25, and on which, exactly symmetrically, a special nut is screwed, 3, which actuates a roller slide, F, that rolls on and inside the resistance column, 25, which, on the one hand, can be fastened on one wall of the room with some known fastening elements, such as dowels with screws and, on the other hand, through a vertical slit, f (fig.7, fig.8) that goes from one end to the other of the column, allowing some bridles, 4.1 and 4.2 (fig. 4) that are fastened on the conventionally upper part of the bed frame, A, to be assembled in two slits, s1 and s2, existing in each roller slide, F, so that, when actuated, the electromotor, 1, operates through the agency of the belt, 2, and the two screwed threaded assemblies, E, simultaneously, thus determining the special nut, 3, to screw up or down and actuate, by pushing when going up and through gravity when going down, the roller slide, F, and, implicitly, the bed frame, A.

Description

RETRACTABLE BED WITH MECHANICAL SYSTEM FOR ADJUSTABLE HEIGHT

The invention refers to a retractable bed equipped with a mechanical system for adjustable height consisting of a bed frame attached to a mechanical system with two slides driven by some threaded vertical spindles actuated simultaneously actuated by an electromotor upon command.

A retractable bed with a driving belt is known, according to patent US2002046423 , which consists bed frame that is adjustable vertically and a pulley system that allows the movement of the bed frame vertically, the respective bed comprising two carriage saddles that are fastened on one of the end sides of the bed frame so that they are displaced horizontally, each of the carriage saddles being mounted so that it may slide on a vertical guide rail with the aid of some rollers, the two carriage saddles being connected through a pull chain or a toothed belt to a counterweight; each pull chain or toothed belt is guided upon a driving sheave at the upper end of that respective guide rail; the driving sheaves are coupled in a rigid manner through the agency of a rod; the rod is connected to a main reel that is interconnected vertically through a driving belt with a counter-reel, the driving belt being used for the revolving actuation of the rod, whereas the counter-reel is driven selectively in one direction or the other through the agency of a motor coupled to a reductor. It has the disadvantage that both the assembly of counterweights and the drum winch-electromotor assembly have a relatively large volume and they extend out of the bed frame, thus occupying some of the work space.

There is knowledge of another vertically retractable bed that requires a bridge or a double ceiling, in which a counterweight pulley tackle is mounted - one that is similar to the system used for garage doors, so that the user may pull the bed up to the ceiling easily and, if needed, he/she may pull it back down to the floor. (www.google.ro/search?q=pat+retractabil+la+tavan&tbm=isch&tbo=u&source=univ& sa=X&ved=2ahUKEwj- l6awqlHgAhUOaFAKHSZwAgQQsAR6BAgFEAE&biw=1366&bih=608#imgrc=B_X4k wZ5-NYAyM:). There are two disadvantages to it: i) the necessity for some space above the ceiling, or a high ceiling where the pulley system may be mounted; ii) the supporting elements are elastic - some bands of special fabric or supporting cables that require the compulsory use of some solid propping legs.

Yet another vertically retractable bed is known, which is seated on a platform that is assembled on a lifting mechanism with a carriage saddle, consisting of a pillar that is fastened on the wall, in which a roller carriage saddle can be lifted or lowered through a pulley tackle that is driven by an electromotor positioned edgewise from the bed and usually hidden in a double wall. The disadvantage consists of the fact that an additional space has to be used which makes the useful space narrower.

The general disadvantage of the mechanically or electrically driven systems used for vertically retractable beds resides in the fact that the mechanism requires a mounting space - sometimes a considerable one - that occupies the entire height of the room, or part of the thickness of the mounting wall, or the width of that wall.

The technical problem that this invention solves is the use of the mounting space required for the driving and lifting mechanism, so that as little space as possible may be used out of the useful space for this purpose.

The advantages of this invention are: i) a small-sized compact driving and lifting mechanism; ii) a reliable mechanism.

Herein below you will find an example of accomplishment of the invention, with reference to the following figures, which represent:

- fig. 1 - an overview of the assembled retractable bed with a mechanical system for variable height

- fig. 2 - an overview of the assembled retractable bed with a mechanical system for variable height

- fig. 3 - an isometric view of the roller slide

- fig. 4 - an isometric view of the bridle

- fig. 5 - a lateral view of the assembled column

- fig. 6 - an assembling detail of the threaded assembly in the resistance column

- fig. 7 - an assembling detail of the roller slide on the threaded spindle

- fig. 8 - an assembling detail of the slide in the assembled column with the highlight of the slit in the resistance column

- fig. 9, fig. 9.1, fig. 9.2, fig. 9.3, fig. 9.6 - images of the special nut - fig. 9.4, fig. 9.5 - images of the half-nuts and the manner in which they are worked from a special nut

- fig. 10, fig. 10.1, fig. 10.2, fig. 10.3 - an isometric view and details of the assembled beam

- fig. 11.1, fig. 11.2, fig. 1.3, fig. 11.4, fig. 11.5, fig. 11.6, fig. 11.7, fig. 11.8 - images of the lifting and lowering mechanism of the propping legs of the bed

- fig. 12, fig. 12.1, fig. 12.2 - an isometric view of the version of bed equipped with the protection frames and assembled writing table; operating mode

- fig. 13, fig. 13.1, fig. 13.2, fig. 13.3, fig. 13.4, fig. 13.5 - view and details of the assembled writing table

According to the invention, the retractable bed with a mechanical system for variable height can be placed anywhere in a building. It consists (fig.1 , fig.2) of a bed frame, A. and a resistance and driving mechanical system made of two identical assembled columns, B, each comprising a resistance column, 25, and both being parallel outlaid at a convenient distance from one another (approximately the width of a bed), on whose upper heads an assembled beam, D, is fastened, on which an electromotor is mounted, 1, which, through the agency of a belt, 2, simultaneously actuates two threaded assemblies, E, mounted in each resistance column, 25, and on which, exactly symmetrically, a special nut is screwed, 3, which actuates a roller slide, F, that rolls on and inside the resistance column, 25, which, on the one hand, can be fastened on one wall of the room with some known fastening elements, such as dowels with screws and, on the other hand, through a vertical slit, f (fig.7, fig.8) that goes from one end to the other of the column, allowing some bridles, 4.1 and 4.2 (fig. 4) that are fastened on the conventionally upper part of the bed frame, A, to be assembled in two slits, s1 and s2, existing in each roller slide, F, so that, when actuated, the electromotor, 1, operates through the agency of the belt, 2, and the two threaded assemblies, E. simultaneously, thus determining the special nut, 3, to screw up or down and actuate, by pushing when going up and through gravity when going down, the roller slide, F, and, implicitly, the bed frame, A. bed frame. A, made of rigidly assembled resistance elements - in our example, these are some resistance and stiffening frames, 5, some stiffening bars, 6, 7 and 8 - of some frames, 9, 10, 11, 12 and some connection angles, 13 and 14, all fastened to one another with known assembling elements that are not mentioned in the figure; on the bed frame, A, the frames 9, 10, 11, 12 can be used to lay a mattress that is not mentioned in the figures, as the bar, 6, allows the rigid fastening of a bridle, 4.1, whereas on the other bar, 8, the other bridle may be fastened, 4.2. The bridles, 4.1 and 4.2, are have some jaws, g1 and g2, that can enter the two slits, s1 and s2, and offer a tight fastening, each of the slits being endowed with a roller slide, E.

On the conventionally lower part of the bed frame, A, some propping legs are assembled, 15 and 16, that can fold through a folding mechanism. M; each of the two assembled columns. B, consists of (fig. 2, fig. 5 and fig. 6): a) A resistance column, 25, initially guided through a bolt fastened on the ceiling, and on which some distance pieces, 26, 27 and 28, are fastened through the agency of some known fasteners, such as screws and nuts and Grower, or spring washer, that are not mentioned in the drawing, through which the entire assembled column, B, is fastened on the wall; b) Some legs, 29, that can travel along the resistance column until they settle on the floor, after which they get fixed on the resistance column, 25, with some known fasteners that are not mentioned on the drawing, to stabilize the entire assembly; c) A threaded assembly, E, consisting of: i. a threaded spindle, 30, whose upper end screws onto a coupling of two slotted half-nuts, 31’ and 31”, at least one of which gets fastened on the threaded spindle, 30, through a threaded fixed stud bolt, 32, which is not mentioned in the drawings, so that the three components together form a common unit; above the halfnut, 31’, a bearing, 33, and a roll, 34, of trapezoidal belt get assembled on the smooth end of the threaded spindle, 30. The roll may be spun around by the trapezoidal belt, 2, when driven by the electromotor, 1 ; the roll, 34, can be fastened at the end of the threaded spindle, 30, with a nut lock and screw bolt, or with a piston pin lock ring that are not mentioned here; this assembly of pieces is laid with the smooth side of the special half-nut, 31”, on a compression thrust bearing, 35; this entire assembly is inserted with the threaded spindle, 30, in the resistance column, 25, to the point where the compression thrust bearing, 35, too gets positioned on the side of the upper end of the resistance column, 25; the whole assembly becomes vertically rigid first by assembling the pillar, 36, and the assembled beam, D, on the bearing, 33, then on the resistance column, 25, with a pair of screw bolt/nut lock/nut pieces, 37, laid diagonally (fig. 6); ii. a roller slide, F (fig. 3, fig. 7, fig. 8) that runs on and inside the resistance column, 25, and that is actuated by a special nut, 31, that is screwed on the threaded spindle, 30, and which it overthrusts so that, during operation, the special nut, 31, does not have a relative motion as opposed to the roller slide, F; the roller slide, F (fig. 3), made of two welded pieces: a rectangular tube, 17, of m x n section, and a U-bar, 18, of m length, p width and r height; inside the tube, 17, lengthwise and diagonally, a roller set, 19, 20, is assembled on an axle, 21, and another roller set, 22, 23, on another axle, 24; a special nut, 31 (fig. 9, fig.9.1, fig.9.2, fig.9.3, fig.9.4, fig.9.5, fig.9,6), with a length of approximately 1.5 Hex, with castellated heads, a, with a depth of 15-20 mm; a special nut, 31, that can be cut in two equal halfnuts, 3T and 31”; when being screwed on the threaded spindle, 30, the half-nuts will form a coupling that, through the agency of the two threaded spindles, 30, and the two compression thrust bearings, 35, will take over the entire weight of the bed frame, A, with the mattresses and of the assembled beam, D; the assembled beam, D, fig.1O, fig.10.1, fig.10.2, fig.10.3) consists of a pillar, 36, for bending strength on the entire length, at both borders, a stiffening, b1 and b2, with a collared throat, c1 and c2, of an identical diameter as the outer diameter of the bearings, 33, with which it gets assembled through a sliding clearance; at both borders there are some holes, d, that allow fastening in the threaded bolt/nut lock, nut, 37, pairs of parts arranged diagonally; in the middle, a flange, 38, is mounted that has an adjustment slot, e, and a driving roller, 39, and two identical idlers, 40’ and 40”; the driving roller can be actuated by an electromotor, 41, that is placed under the pillar, 36; the driving roller, 39, actuates the trapezoidal belt, 2, that, in turn, actuates the rollers, 34, and that is stretched by the idlers, 40’ and 40”, while rotating the flange, 38, and then fastening it with a screw, 42.

Folding mechanism, M, that consists - both on the right side and the left side of the bed - of a thin bar, 43, that has a crank at each end, 44 and 45; one of the cranks, 44, is fastened on the resistance column, 25, with an unmentioned bolt that allows it to fold; the other crank, 45, is fastened on the propping legs, 15, respectively 16, with two bolts, 46 and 47, of which one bolt, 45, is only fastened on the propping leg, whereas the other bolt, 46, is also an axis of rotation for the propping leg, 15, respectively 16, as it is fastened on the frame, 12; actuates the crank continues its movement

When the bed is its lowermost position, owing to gravity, the propping legs, 15 and 16, stand vertically, allowing the bed to lean on them; when the bed is lifted, the propping legs have a vertical position as well, close by the end of the upward stroke, where the crank, 44, fastened on the resistance column, 25, meets a bolt, 48 (fig. 11.6), that is fastened on the column, 25; the bed frame, A, continues its movement, the bolt, 48, actuates the crank, 44, and - through the agency of the thin bar - 43 - actuates the crank, 45, on the propping legs, 15, 16, forcing them to revolve around the bolt, 46, and fold underneath the frame, 12. when moving downwards, there is a reversed phenomenon, the propping legs, 15 and 16, going down in a vertical position as soon as the bed starts going down.

Manner of operation: Supposing that the bed is in elevated position, when the electronic command is triggered, the electromotor, 41, is put into operation and actuates the roller, 39, which actuates the trapezoidal belt, 2, which, in turn, actuates the rollers, 34, and, implicitly, the threaded spindle, 30, which forces the special nut, 31, to screw down the thread of the threaded spindle, 30, allowing the roller slide, F, to slide using the gravitational force, together with the bed frame, A.

If the bed is in its lowermost position, when the electronic command is triggered, the electromotor, 41, has a reverse operation, thus actuating the roller, 39, that actuates the trapezoidal belt, 2, which actuates the rollers, 34, and, implicitly the threaded spindle, 30, which forces the special nut, 31, to screw up the thread of the threaded spindle, 30, thus forcing the roller slide, F, to slide up, together with the bed frame, A

In a second version, the retractable bed with a mechanical system for variable height from the first version receives: an upper protection frame, 49, a lower protection frame, 50, and an assembled writing table, WT (fig. 12), which, when the bed is in horizontal position, lies in the lowermost position as well, in the sense that it lies on the floor; when the bed is being lifted, the writing table, WT, is also lifted to its uppermost position (fig. 12.1); when the bed is in its uppermost position (fig. 12.2), the assembled writing table, WT, can be used in ergonomic conditions;

The assembled writing table, WT (fig. 13), consists of: a table countertop, 51 (fig. 13.1), to which two connection angles, 52 and 53, are assembled laterally, each of them having two guide rollers, 54, 55, respectively 56, 57; a plate, 58, (fig.13.2) that is fastened on each of the resistance columns, 25, on which an upper idler, 59, is fixed on an axle, 60, and a lower idler, 61 (fig.13.3) is fixed on an axle, 62, in this order_± and they are stiffened using a piece of sheet, 63, that is, in turn, fastened on a plate, 58. The idlers allow the tensioning of a belt, 65; a counterweight, 59, that has the aspect of a plate is fastened on the two belts, 25, mounted on the two resistance columns. on each plate, 58, a guide, 64, is mounted in which the guide rollers, 54, 55, respectively 56, 57, that are fastened on the two connection angles, 52, 53, of the two connection angles, 52 and 53, that are fastened on the belt, 65, on its free side; the mounting of the counterweight, 59, of the connection angles, 52 and 53, and of the table countertop, 51, on the belt, 25, is done in such a manner that the downward movement of the counterweight, 59, coincides with the upward movement of the table countertop, 51, and vice versa;

Manner of operation (fig.13.4, fig.13.5): the assembly is built so that the uppermost position of the table countertop, 51, is the ergonomic working position of a table user who is seated; before reaching its uppermost position, the table countertop, 51 - which goes up when the counterweight, 59, goes down using the gravitational force - it is pressured by the frame, 10, which touches the upper edge of the connection angles, 52 and 53 (fig.13.4 and fig.13.5), tangentially; from that point forward, the lifting of the bed no longer influences the position of the table countertop, 51; when the bed is pulled down, from the point where the frame, 10, touches the connection angles, 52 and 53, tangentially and down to the final position of the bed, the pressure on the table countertop, 51, is greater than the mass of the counterweight, 59, which it lifts concomitantly with the lowering of the table countertop, 51.

Bibliography

- US2002046423

- www.Qooale.ro/search?q=pat+retractabil+la+tavan&tbm=isch&tbo=u&sour ce=univ&sa=X&ved=2ahUKEwi- l6awqlHaAhUQaFAKHSZwAgQQsAR6BAaFEAE&biw=1366&bih=608#ima rc=B X4kwZ5-NYAvM:k

Claims

1. Retractable bed with a mechanical system for variable height, characterised by the fact that it is made (fig.1, fig.2) of a bed frame (A) and a resistance and driving mechanical system consisting of two identical assembled columns (B), each of them comprising a resistance column (25), displaced parallelly at a convenient distance (approximately a bed width), on the upper heads of which an assembled beam (D) is fastened on which an electromotor (1) is mounted which, through the agency of a belt (2), simultaneously actuates two threaded assemblies (E) mounted in each of the resistance columns (25), and on which - exactly symmetrically - a special nut (3) is screwed that actuates a roller slide (F) that travels on and inside the resistance column (25), which, on the one hand, can be fastened on one wall of the room with some known fastening elements, such as dowels with screws and, on the other hand, through a vertical slit, f (fig.7, fig.8) that goes from one end to the other of the column, allowing some bridles, 4.1 and 4.2 (fig. 4), that are fastened on the conventionally upper part of the bed frame, , to be assembled in two slits, (s1 and s2), existing in each roller slide (F) so that, when actuated, the electromotor (1) operates through the agency of the belt (2), and the two threaded assemblies (E) simultaneously, thus determining the special nut (3) to screw up or down and actuate - by pushing when going up and through gravity when going down - the roller slide, (F) and, implicitly, the bed frame (A).

2. Retractable bed with a mechanical system for variable height according to Claim 1 , characterised by the fact that the bed frame (A) is made of some rigidly assembled resistance elements - in our example, these are some resistance and stiffening frames (5), some stiffening bars (6, 7 and 8) - of some frames (9, 10, 11, 12) and some connection angles (13 and 14), all fastened to one another with known assembling elements that are not mentioned in the figure; on the bed frame (A), the frames (9, 10, 11, 12) can be used to lay a mattress that is not mentioned in the figures, as the bar (6) allows the rigid fastening of a bridle (4.1), whereas on the other bar (8), the other bridle may be fastened (4.2). The bridles (4.1 and 4.2) have some jaws

9 (g1 and g2) that can enter the two slits (s1 and s2), and offer a tight fastening, each of the slits being endowed with a roller slide (E); on the conventionally lower part of the bed frame (A), some propping legs are assembled (15 and 16) that can fold through a folding mechanism (M); each of the two assembled columns (B) consists (fig.2, fig.5, fig.6): a) of resistance column (25), initially guided through a bolt fastened on the ceiling, and on which some distance pieces (26, 27 and 28) are fastened using some known fasteners, such as screws and nuts and Grower, or spring washer, that are not mentioned in the drawing, through which the entire assembled column (B) is fastened on the wall; b) some legs (29) that can travel along the resistance column until they settle on the floor, after which they get fixed on the resistance column (25) with some known fasteners that are not mentioned on the drawing, to stabilize the entire assembly; c) a threaded assembly (E) consisting of i) a threaded spindle (30) whose upper end screws onto a coupling of two slotted half-nuts (31’ and 31”), at least one of which gets fastened on the threaded spindle (30) through a threaded fixed stud bolt (32), which is not mentioned in the drawings, so that the three components together form a common unit; above the half-nut (31’), a bearing (33) and a roll (34) of trapezoidal belt get assembled on the smooth end of the threaded spindle (30). The roll may be spun around by the trapezoidal belt (2) when driven by the electromotor (1); the roll (34) can be fastened at the end of the threaded spindle (30) with a nut lock and screw bolt, or with a piston pin lock ring that are not mentioned here; this assembly of pieces is laid with the smooth side of the special half-nut (31”) on a pressure thrust bearing (35); this entire assembly is inserted with the threaded spindle (30) in the resistance column (25) to the point where the pressure thrust bearing (35) gets positioned on the side of the upper end of the resistance column (25); the whole assembly becomes rigid first by assembling the pillar (36), the assembled beam (D) on the bearing (33), then on the resistance column (25) with a pair of screw bolt/nut lock/nut pieces (37), laid diagonally (fig. 6); ii) a roller slide, F (fig. 3, fig. 7, fig. 8) that runs on and inside the resistance column (25) and that is actuated by a special nut (31) that is screwed on the threaded spindle (30) and that it overthrusts so that, during operation, the special nut (31) does not have a relative motion as opposed to the roller slide (F); a roller slide (F) (fig. 3), made of two welded pieces: a rectangular tube (17) of m x n section, and a U- bar (18), of m length, p width and r height; inside the tube (17) a roller set (19, 20) is assembled on an axle (21) lengthwise and diagonally, whereas another roller set (22, 23) is assembled on another axle (24); a castellated nut (31) (fig. 9, fig. 9.1, fig. 9.2, fig. 9.3, fig. 9.4, fig. 9.5, fig. 9,6), with a length of approximately 1.5 Hex (and castellated heads (a), with a depth of 15-20 mm; special nut (31) that can be cut in two equal half-nuts (31’ and 31”); when being screwed on the threaded spindle (30), the half-nuts will form a coupling that, through the agency of the two threaded spindles (30), and the two pressure thrust bearings (35) will take over the entire weight of the bed frame (A) with the mattresses and of the assembled beam (D); the assembled beam (D) (fig.1O, fig.10.1, fig.10.2, fig.10.3) consists of a pillar (36) for bending strength on the entire length, at both borders, a stiffening (b1 and b2) with a collared throat (c1 and c2) of an identical diameter as the outer diameter of the bearings (33) with which it gets assembled through a clearance for sliding; at both ends there are some holes (d) that allow fastening in the threaded bolt/nut lock, nut (37) pairs of parts arranged diagonally; in the middle, a flange (38) is mounted that has an adjustment slot (e) and a driving roller (39) and two identical idlers (40’ and 40”); the driving roller can be actuated by an electromotor (41) that is placed under the pillar (36); the driving roller (39) actuates the trapezoidal belt (2) that, in turn, actuates the rollers (34) and that is stretched by the idlers (40’ and 40”), while rotating the flange (38), and then fastening it with a screw (42); a folding mechanism (M) that consists - both on the right side and the left side of the bed - of a thin bar (43) that has a crank at each end (44 and 45); one of the cranks (44) is fastened on the resistance column (25) with an unmentioned bolt that allows it to fold; the other crank (45) is fastened on the propping legs (15) and respectively (16) with two bolts (46 and 47), of which one bolt (45) is only fastened on the propping leg, whereas the other bolt (46) is also an axis of rotation for the propping leg (15) and respectively (16), as it is fastened on the frame (12); when the bed is its lowermost position, owing to gravity, the propping legs (15 and 16) stand vertically, allowing the bed to lean on them; when the bed is lifted, the propping legs have a vertical position as well, close by the end of the upward stroke, where the crank (44) fastened on the resistance column (25) meets a

11 bolt (48) (fig. 11.6) that is fastened on the column (25); the bed frame (A) continues its movement, the bolt (48) actuates the crank (44) and - through the agency of the thin bar - 43 - actuates the crank (45) on the propping legs (15, 16), forcing them to revolve around the bolt (46) and to fold underneath the frame (12); when moving downwards, there is a reversed phenomenon, the propping legs (15 and 16) going down in a vertical position as soon as the bed starts going down;

Manner of operation: Supposing that the bed is in elevated position, when the electronic command is triggered, the electromotor (41) is put into operation and actuates the roller (39) that actuates the trapezoidal belt (2), which, in turn, actuates the rollers (34) and, implicitly, the threaded spindle (30), which forces the special nut (31) to screw down the thread of the threaded spindle (30), allowing the roller slide (F) to slide using the gravitational force, together with the bed frame (A); when the bed is in the lowermost position, when the electronic command is triggered, the electromotor (41) has a reverse operation, thus actuating the roller (39), which actuates the trapezoidal belt (2), which actuates the rollers (34), and, implicitly the threaded spindle (30), which forces the special nut (31) to screw up the thread of the threaded spindle (30), thus forcing the roller slide (F) to slide up, together with the bed frame, A. Retractable bed with a mechanical system for variable height according to Claim 1 , characterised by fact that, in a second version, the retractable bed with mechanical system for variable height receives: an upper protection frame (49), a lower protection frame (50) and an assembled writing table (WT) (fig.

12) which, when the bed is in horizontal position, lies in the lowermost position as well, in the sense that it lies on the floor; when the bed is being lifted, the writing table (WT) is also lifted to its uppermost position (fig. 12.1); when the bed is in its uppermost position (fig. 12.2), the assembled writing table (WT) can be used in ergonomic conditions; the assembled writing table (WT) (fig.

13) consists of: a) a table countertop (51) (fig. 13.1), to which two connection angles (52 and 53) are assembled laterally, each of them having two guide rollers (54, 55, respectively 56, 57); on each resistance column (25), a plate (58) is fastened, (fig.13.2), on which an upper idler (59) is fixed on an axle

12 (60), and a lower idler (61) (fig.13.3) is fixed on an axle (62), in this order, and they are stiffened using a piece of sheet (63) that is, in turn, fastened on a plate (58). The idlers allow the tensioning of a belt (65); a counterweight (59) that has the aspect of a plate is fastened on the two belts (25) mounted on the two resistance columns; on each plate 58, a guide (64) is mounted in which the guide rollers (54, 55, respectively 56, 57) that are fastened on the two connection angles (52, 53) of the countertop of the table (51) can travel; connection angles (52 and 53) that are fastened on the belt (65), on its free side; the mounting of the counterweight (59), the connection angles (52 and 53) and the table countertop (51) on the belt (25) is done in such a manner that the downward movement of the counterweight (59) coincides with the upward movement of the table countertop (51) and vice versa; Manner of operation (fig.13.4, fig.13.5): the assembly is built so that the uppermost position of the table countertop (51) is the ergonomic working position of a table user who is seated; before reaching its uppermost position, the table countertop (51) - which goes up when the counterweight (59) goes down using the gravitational force -is pressured by the frame (10), which touches the upper edge of the connection angles (52 and 53) (fig.13.4 and fig.13.5) tangentially; from that point forward, the lifting of the bed no longer influences the position of the table countertop (51); when the bed is pulled down, from the point where the frame (10) touches the connection angles (52 and 53) tangentially and down to the final position of the bed, the pressure on the table countertop (51) is greater than the mass of the counterweight (59), which it lifts concomitantly with the lowering of the table countertop (51).

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