Retractable bed with variable lifting system

Abstract

The invention relates to a retractable bed with a mechanical system for variable height. The bed, according to the invention, consists of a system made up of two assembled, quasi-identical columns (A and A'), inside which, by means of an electric motor (5), a threaded rod (9) is driven by means of each of them, each rod (9) driving an assembled cardan sledge (B) which can run inside the assembled columns (A and A'), the assembled cardan sledges (B) being able to raise and lower both a bed frame (C) provided with two folding mechanisms (D) and a device (E) for positioning a work table.

Description

[0001] RETRACTABLE BED WITH VARIABLE LIFTING SYSTEM

[0002] The invention relates to a retractable bed with a variable-height system consisting of a bed frame attached to a mechanical system with two cardan sliding sleds operated by vertical threaded spindles driven simultaneously by an electric motor each.

[0003] Is known a retractable bed with drive belt, according to invention US2002046423, comprising a vertically adjustable bed frame and a pulling device for moving said bed frame in the vertical direction, said bed comprising two carriages which are fixed to an end face of the bed frame such that they are horizontally spaced apart from each other, each of said carriages being supported so that it can be moved on a vertical guide rail by means of rollers, said two carriages being each connected by means of a toothed towing chain or toothed belt to a counterweight each traction chain or toothed belt is guided on a drive wheel at the upper end of the respective guide rail; the drive wheels are rigidly coupled by means of a coupling rod the coupling rod is connected to a main drum vertically interconnected by a drive belt with a counter-drum; the said drive belt being used for the rotary actuation of the coupling rod; and the counter-drum is driven selectively in one direction or the other by means of a motor coupled to a reduction gear. It has the disadvantage that both the counter-drive assembly and the winch-drum-electric motor assembly are relatively large in volume and protrude from the bed frame, taking up useful space.

[0004] We also know of a vertically retractable bed that requires a loft, or a double ceiling, in which a pulley system with counterweights is mounted - similar to the system used in garage doors, so that the user can easily raise the bed to the ceiling, and, if necessary, pull it to floor level.

[0005] (www.google.ro / search?q=pat+retractable+to+the+ceiling&tbm=isch&tbo=u&source= univ&sa=X&ved=2ahUKEwj- l6awqlHgAhAhllOaFAKHSZwAgQQsAR6BAgFEAE&biw=1366&bih=608#imgrc=B_X 4kwZ5-NYAyM:). Its disadvantages are: i) the need for a space beyond the ceiling, or a high ceiling in which the traction device can be mounted; ii) the supportingelements are elastic - strips of special cloth or supporting cables, which forces the use of solid supporting legs.

[0006] Also known is a vertically retractable bed, where the bed is placed on a platform assembled to a trolley lifting mechanism, consisting of a post fixed to the wall, in which a roller trolley can be raised or lowered by a pulley system driven by an electric motor positioned to the side of the bed and usually hidden in a double wall. The disadvantage is the use of extra space which reduces the usable space.

[0007] The general disadvantage of mechanically or electrically operated mechanical systems used for vertically retractable beds is that the mechanism requires a - sometimes considerable - mounting space, which is taken either from the height of the room, the thickness of the mounting wall or the width of the mounting wall.

[0008] It is also known a retractable bed with a mechanical system for variable height, subject of patent RO 134297 A2, which can be placed in any place of an enclosure, consisting of a bed frame and a mechanical resistance and actuation system, consisting of two identical assembled columns, each of which has a resistance column, spaced parallel at a distance approximately the width of a bed, to the upper ends of which is fixed an assembled cross-member on which is mounted an electric motor which, by means of a belt, simultaneously drives two threaded assemblies mounted in each resistance column and on which - exactly symmetrically - is screwed a special nut, each of which drives a sledge with rollers running on and inside the resistance column which, on the one hand, can be fixed - by means of known fasteners, e.g. bolted dowels

[0009] - to a wall of the enclosure and, on the other hand, by means of a slot running along its entire vertical axis, enables flanges - fixed to the upper conventional part of said bed frame - to be assembled in two slots provided in each roller sledge, so that, on command, the electric motor simultaneously actuates, by means of the belt, the two threaded assemblies which force the special nut to move upwards, or downwards by threading, thus actuating - by thrust, when going upwards, and by gravity, when going downwards - the roller sledge and, consequently, the bed frame.

[0010] The major disadvantages of this invention are:

[0011] - during operation, the use of the belt with the rollers causes vibrations and makes noise,

[0012] - during operation, the locking of the translation nuts on the bolts cannot be controlled, due to the impossibility of correlating the execution tolerances of the translation sledge assembly with the execution tolerances of the bolts / translation nuts assembly, so that at least one of the translation nuts may lock, leaving the bed suspended, while the electric motor is forced, because it fails to close on the command given by one of the travel sensors. The technical issues that this invention solves are: a) vibration and noise canceling in the small useful mounting space of the actuating and lifting mechanism, and b) canceling random locking of the translation nuts on the actuating screws.

[0013] The advantage of this invention lies in the realization of a compact and small volumetric, reliable, silent and safe actuating and lifting mechanism.

[0014] An embodiment of the invention is given below with reference also to the following figures which represent:

[0015] - fig.1.1 , 1.2, 1.3, 1.4 - General view of the assembled retractable bed with variable height system

[0016] - fig.2 - Detail U in fig.1 .1

[0017] - fig.3 - Detail T in fig.1 .1

[0018] - fig.4 - side view of the lower part of the retractable bed with variable height system, assembled

[0019] - fig .5, fig.6 - top view of the column area of the assembled retractable bed with variable height system

[0020] - fig.7 - side view of the retractable bed with variable height system, assembled

[0021] - fig.8 - side view of the lower part of the retractable bed with variable height system, assembled, showing the assembled sledge, B

[0022] - fig.9 - Z-Z section through assembled column, A.

[0023] - fig.10.1, fig.10.2 - views of the assembled sledge, B

[0024] - fig.11.1 , fig.11.2, - top view and isometric view of the frame assembly - translation nut

[0025] - fig.12.1 , fig.12.2, fig.12.3, fig.12.4 - isometric overall view, partial and details of the folding mechanism, D, lowered

[0026] - fig.13.1 , fig.13.2, fig.13.3, fig.13.4 - isometric overview, partial and details of the folding mechanism, D, raised

[0027] - fig.14.1, fig.14.2 - front and side view of the positioning device of a work table, E

[0028] - fig.15.1 ... fig.15.7, - isometric overall, partial and detail view of the positioning device of a work table, E, lowered and raised, together with the folding mechanism, D, lowered and raised;

[0029] - fig.16 - explanation of how the indexing of the work table positioning device, E.

[0030] The retractable bed with mechanical system for variable height, according to the invention, consists (f ig .1.1 , f ig .1.2, f ig .1.3, f ig .1.4, fig .2) of a system consisting of two assembled columns, A and A', quasi-identical, inside which, by means of an electric motor, 5, a threaded rod, 9, each driving an assembled cardan sledge, B, which run inside the assembled columns, A and A', assembled cardan sledges, B, which can raise and lower both a bed frame, C, provided with two folding mechanisms, D, and a device for positioning a work table, E:

[0031] - the assembled columns, A and A' (fig.1.1, fig.1.2, fig.1.3, fig.1.4) consist of a wallmounting plate, 1 and 1' respectively, spaced parallel to each other at a suitable distance (approximately the width of a bed) - the plates are fixed to the wall by means of fasteners not shown on the drawing - a resistance column, 2 and 2' respectively, is removably mounted on each of them; a resistance column is assembled on each resistance column (fig.2, fig.2, fig.3, fig.4, fig.5, fig.8), in order, starting from the lower part, a lower cover, 3, detachably fixed to the resistance column, 2, respectively 2', a radial bearing, 4, not shown on the drawing, being assembled in the lower cover, 3; an electric motor, 5, is fixed to the lower cover, 3, by means of double threaded left / right threaded studs, 6; the electric motor, 5, drives a special axle, 7 (fig.4, fig.8), to which, by means of an elastic coupling, 8, a threaded rod, 9, is axially assembled, which, at the other end, is fixed in a pressure bearing, 10 - not shown on the drawing - fixed in an upper cover, 11 , removably fixed to the upper end of the resistance column, 2; in section (fig-9), each resistance column, 2 or 2', has longitudinally a resistance structure, a , two lower running tracks, b , and two upper running tracks, b , for the assembled sledge rollers, B, a running track, c, arranged longitudinally and symmetrically to the running tracks, b' , towards the wall mounting plate, 1 and 1' respectively, two rolling grooves, d , arranged longitudinally and symmetrically, towards the bed frame, C, several threaded holes, e, arranged at the ends, in which the lower cover, 3, and the upper cover, 11, are fixed; at the upper end, both assembled columns, A and A', having assembled towards the inside of the assembly, mirror-image; each a sill, 37 and 38 (figs.14,1, Fig. 14.2), fixed at the same height. in each assembled column, A and A', one assembled cardan sledge, B (fig.9, fig.10.1, fg.10.2, fig.11.1, fig.11.2); consisting of a resistance body, 12, at the lower end of which a pair of rollers, 14' can be assembled on a lower axle, 13, fixed in two lower arms, f_ , of the body, 12; and at the upper end a pair of rollers, 14' can be assembled on an upper axle, 13', fixed in two upper arms, g , of the body, 12; a bolt, 15' is removably fixed under the upper axle; on the resistance body, 12, above the rollers, 14, by means of two bolts, 16, a cardan assembly consisting of two hinges, 17 and 18, is attached, with free rotational movement, which, at the other end, is attached, with free rotational movement - by means of two identical bolts, 19, arranged axially - to a frame, 20, which in the example given is rectangular, inside which a translation nut, 21 , which meshes with the threaded rod, 9, is inserted with play; arranged at 90 degrees on the frame, 20, are assembled axially on either side of the frame, two identical guide rollers, 22 and 23, whose axles, 24 and 25 respectively, are fixedly assembled both in the frame, 20, and in the translation nut, 21 ; in the hinge mountings, 17 and 18, the assembly of frame, 20, and translating nut, 21 , being able to move smoothly in a cut-out, k, in the resistance body, 12, in such a way that the guide roller, 22, fits with small clearance between the upper arms, g , of the resistance body, 12; the other guide roller, 23, being guided in the raceway, c, in the resistance column, 2 or 2' (fig.9). by the bolt, 15, and the axle, 13, and assembled between the arms, f and g, on each assembled sled, B, is hooked / fixed one plate, 24 (fig.2, fig.4,fig.5, fig.6, fig.7, fig.8) in the shape of an "L"; to the two plates, 24, on the two assembled sled sleds, B, is fixed the bed frame, C (fig.1.1 , fig.1.3, fig.7), consisting of rigidly assembled resistance elements - in our example being "L" section contour frames, conventionally called: upper frame, 25, right frame, 26, lower frame, 27, left frame, 28, and a "T" section middle profile, 29, all fixed to each other with collars and by means of known assembling members not mentioned in the figure, all assembled in such a way that one or two mattresses, not mentioned in the figures, can be placed between them; in the upper part of each plate, 24, a U-shaped locus, n, is machined (fig.15.3.) to the underside of the bed frame, C, with support legs, 30 and 31 (Fig. 1.3), which can be folded, in mirror image, towards the inside of the bed frame, by means of a folding mechanism, D, consisting, on the right side of the bed, of a thin bar, 32, having at the upper end - situated outside the bed frame, C, a lug, 33, having a hole, h, oriented to the right-top; and at the lower end - situated inside the bed frame, C, the support foot, 30, assembled to the bar, 32, by means of a special screw, 36; to the right-hand frame, 26, the bar, 32, is assembled by means of at least two cylindrical sliding- adjusting couplings, 35, fixed to the right-hand frame, 26; a folding mechanism, D, consisting, on the left side of the bed, of a slender bar, 32, having at the upper end - situated outside the bed frame, C, a lug, 34, having a needle, m, pointing to the left- upward and at the lower end - situated inside the bed frame, C, the support foot, 31 , assembled to the bar, 32, by means of a special screw, 36; to the left frame, 28, the bar, 32, is assembled by means of at least two cylindrical sliding-fit couplings, 35, fixed to the right frame, 28;

[0032] On each resistance column, 2 and 2' respectively, a threshold, 38 and 37 respectively, is fixed at the top inwards at the same height (fig.13.2, fig.13.4, fig.14.1 , fig.14.2); the device for positioning a work table, E (fig.14.1 , fig.14.2, fig.15.1, fig.15.2, fig.15.3, fig.15.4, fig.15.5, fig.15.6, fig.15.7) is made up of two identical L- shaped supports, 39, slidingly inserted and fixed by means of bolts, 50, positioned equidistantly between two identical strips, 40, whose external dimension is so calculated that they can be assembled, in order, from bottom to top, on a lower axle, 41 , with rollers, 42, on an intermediate axle, 43, with rollers, 42, and on two coaxial upper half-axles, 44 respectively 45, with rollers, 42 ; the half-axes, 44 and 45, being so fixed that, when assembled, between the bands, 40, the plates, 24, can slide freely ; the supports, 39, being assembled between the lower axle, 41, and the intermediate axle, 43 ; the rollers, 42, assembled on the axles and half-axes, being able to slide in the rolling seats, d (fig- 9), arranged longitudinally and symmetrically in each of the resistance columns, 2, respectively 2' ; the supports, 39, having several recesses, s (fig. 16), on the side facing the upper bed frame, 25, which are cut on the upper side of the bed frame, 25, to adjust the height of the work table according to the operator's height; in the 'lowered' position of the bed frame, C (fig.14.1), the lower roller axle, 41 , with rollers, 42, is not in the roll recesses, d , the intermediate roller axle, 43, with rollers, 42, and the two coaxial upper half-axles, 44 and 45, respectively, with rollers, 42, are in the roll recesses, d ; on the outside of the belts, 40, there is mounted an assembly consisting of two identical blades, 46, fixed at the bottom to a spacer, 47, into which an indexing screw, 48, can be inserted, and at the top, fixed by a spindle, 49, with rollers, 42, which can be seated in the rolling seats, d , by the use of the indexing screw, 48, on the spacer, 47, the assembly of belts, 40, with rollers, 42, can be raised or lowered easily, by sliding, in the resistance columns, 2 respectively 2'. on the two identical supports, 39, in the shape of an a horizontal plate can be assembled as a work table, not shown on the drawing.

[0033] How it works:

[0034] With the simultaneous operation of the two motors, 5, the two threaded rods, 9, begin to rotate, driving the translation nuts, 21 , which, by means of the cams, 17 and 18, drive the two assembled cardan sledges, B, which begin to slide upwards in the two resistance columns, 2, respectively 2', driving, by means of the bolt, 15 and the axle, 13, the plates, 24, on which the bed frames, C, are assembled; at a given moment, in the upward movement, the plates, 24, hook the axle, 49, with rollers, 42, in the recesses, n , forcing the rollers to slide upwards in the rolling recesses, d , arranged longitudinally and symmetrically in the resistance columns, 2, respectively 2' ; at the moment the indexing screw, 48, reaches the first bolt, 50, above it, it will start to drive the work table positioning device, E, upwards.

[0035] The upward motion will continue until one of the assembled cardan shafts, B, touches a connector, not shown in the drawings, for simultaneously stopping both electric motors, 5.

[0036] When lowering, the phenomenon is exactly the reverse: the threaded rods, 9, rotate in the opposite direction, forcing the assembled cardan joint, B, to lower, also driving the bed frame, C, and the work table positioning device, E.

[0037] In the assembled cardan sledge, B, the subassembly - consisting of the resistance body, 12, hinges, 17 and 18, frame, 20, translation nut, 21 , which meshes with the threaded rod, 9 , with the guide roller, 22, sliding between the upper arms, fl , of the resistance body, 12 ; the other guide roller, 23, guiding in the rolling path, c, of the resistance column, 2 or 2' (fig. 9) - functions as a universal joint, eliminating the possibility of the translation nuts, 21 , locking on the threaded rod, 9, during the screwing movement.

[0038] In the "lowered" position of the bed, due to gravity, the legs, 30 and 31 , stand upright with the bed resting on them;

[0039] When simultaneously operating the two electric motors, 5, the feet, 30 and 31 , remain in the vertical position until near the end of the vertical stroke, when the claws, g and h, of the two levers, 33 and 34, respectively, meet the thresholds, 38 and 37, respectively (fig.13.2, fig.13.4, fig.14.1, fig.14.2), fixed on the resistance columns, 2, respectively 2'; the bed frame, C, continuing its displacement, the thresholds, 38, respectively 37, act on the levers, 33, respectively 34, and - through the thin bars, 32, force the legs, 30, 31 , to rotate and to fold under the frame, 27;

[0040] On the way down, the phenomenon is exactly the opposite, the legs, 30, 31 , lowering into an upright position as soon as the bed starts to descend;

[0041] To the extent that conditions require horizontal control, both the bed frame, C, and the work-table device, E, may be provided at the bottom with symmetrical screw-bolt angle adjustment mechanisms. Bibliography

[0042] - US2002046423

[0043] - EN 134297 A2

Claims

RETRACTABLE BED WITH VARIABLE LIFTING SYSTEMCLAIMS1. Retractable bed with variable height system, characterized in that it consists (fig.1.1, fig.1.2, fig.1.3, fig.1.4, fig.2) of a system consisting of two assembled columns (A and A') quasi-identical, inside which, by means of an electric motor (5), a threaded rod (9) is driven by means of each of them, each rod driving an assembled cardan sledge (B) which runs inside the assembled columns (A and A'), the assembled cardan sledges (B) being able to raise and lower both a bed frame (C) provided with two folding mechanisms (D) and a device for positioning a work table (E); the assembled columns (A and A') (fig.1.1, fig.1.2, fig.1.3, fig.1.4) consist of a wall-fixing plate (1 and T respectively) spaced parallel to each other at a suitable distance (approximately the width of a bed) - the plates are fixed to the wall by means of known assembling devices - a resistance column (2 and 2' respectively) is removably mounted on each of them; a resistance column (2 and 2' respectively) is assembled on each resistance column (fig.2, fig.3, fig.4, fig.5, fig.8), in sequence, starting from the lower part, a lower cover (3) removably fixed to the resistance column (2, 2' respectively), in which lower cover (3) a radial bearing (4) is assembled; an electric motor (5) is fixed to the lower cover (3) by means of double threaded left / right threaded left / right threaded studs (6); the electric motor (5) drives a special shaft (7) (fig.4, fig.8), to which, by means of an elastic coupling (8), a threaded rod (9) is axially assembled by means of a threaded coupling (8), which, at the other end, is fixed in a pressure bearing (10) fixed in a top cover (11), removably fixed to the upper end of the resistance column (2); in cross-section (fig.9), each resistance column (2 or 2') has longitudinally a resistance structure (a), two lower conventional raceways (b) and two upper conventional raceways (b ), for the assembled sledge rollers (B), a raceway (c) arranged longitudinally and symmetrically to the raceways (bl), conventionally towards the wall mounting plate (1, respectively T), two rolling recesses (d), arranged longitudinally and symmetrically towards the bed frame (C), several threaded holes (e), arranged at the ends, in which the lower cover (3) and the upper cover (11) are fixed; at the upper end, both assembled columns (A and A') having assembled towards the inside of the assembly, mirror-image; each a sill (37 and 38) (fig.14,1, fig.14.2), fixed at the same height;in each assembled column (A and A'), one assembled cardan sledge (B) can be transposed (fig.9, fig.10.1, fg.10.2, fig.11.1 , fig.11.2); consisting of a resistance body (12), at the ends of which a pair of rollers (14) can be assembled on a lower axle (13) fixed in two lower arms (f ) of the body (12) and a pair of rollers (14') on an upper axle (13') fixed in two upper arms (q) of the body (12); a bolt (15) is removably fixed under the upper axle; on the resistance body (12), above the rollers (14), by means of two bolts (16), two hinges (17 and 18) are attached at one end, with free rotational movement, which, at the other end, are attached, with free rotational movement, to two axially arranged bolts (19) fixed in a frame (20), which may be rectangular, inside which a translation nut (21) engages with the threaded rod (9); two identical guide rollers (22 and 23) are mounted axially on either side of the frame (20) at 90 degrees to the frame (20), the axles (24 and 25 respectively) of which are fixedly mounted both in the frame (20) and in the translation nut (21); in assembly, on hinges (17 and 18), the resistance frame (20) and translating nut (21) assembly being able to move with play in a cutout (k) in the resistance body (12) in such a way that the guide roller (22) enters with small play between the upper arms (g) of the resistance body (12); the other guide roller (23) being guided in the raceway (c) of the resistance column (2 or 2') (fig.9); in the assembled cardan sledge (B), the subassembly - consisting of the resistance body (12), hinges (17 and 18), frame (20), translation nut (21) meshing with the threaded rod (9), with the guide roller (22) sliding between the upper arms (g) of the resistance body (12); the other guide roller (23) being guided in the rolling path (c) of the resistance column (2 or 2') (fig.9) - functions as a cardan, eliminating the possibility of the translation nuts (21) jamming on the threaded rod (9) during the screwing movement; from bolt (15) and axle (13), and assembled between the arms (f_and g), on each assembled sled (B), one plate (24) (fig.2, fig.4, fig.5, fig.6, fig.7, fig.8) in the shape of "L" is hooked / fixed; a bed frame (C) (fig.1.1, fig.1.3, fig.7), made of rigidly assembled resistance elements - in our example being "L" section contour frames, called: top frame (25), right frame (26), bottom frame (27), left frame (28) and a "T" section middle profile (29), all fixed to each other with collars and by means of known self-assembly members, all so assembled that between them one or two mattresses can be placed ; in the upper part of each plate (24), a "U" shaped place (n) is machined (fig15.3.); to the lower part of the bed frame (C) being assembled some support feet (30 and 31) (fig.1.3), which canbe folded, mirror-image, towards the inside of the bed frame, by means of a folding mechanism (D) consisting, on the right side of the bed, of a thin bar (32) having at the upper end - located outside the bed frame (C), a lug (33) having a needle (h) oriented to the right-top; and at the lower end - located inside the bed frame (C), the support foot (30), assembled to the bar (32) by means of a special screw (36); to the right-hand frame (26), the bar (32) is assembled by means of at least two cylindrical sliding- adjusting couplings (35), fixed to the right-hand frame (26); a folding mechanism (D) consisting, on the left side of the bed, of a slender bar (32), having at the upper end - located outside the bed frame (C), a guide (34) with a needle (m) oriented upwards to the left; and at the lower end - located inside the bed frame (C), a support foot (31) assembled to the bar (32) by means of a special screw (36); to the left frame (28), the bar (32) is assembled by means of at least two cylindrical sliding-fit couplings (35), fixed to the right frame (28) ; on each resistance column (2, 2' respectively), at the top, inwards, at the same height, a threshold (38, 37 respectively) is fixed (fig.13.2, fig.13.4, fig.14.1 , fig.14.2) ; with the simultaneous actuation of the two motors (5), the two threaded rods (9) begin to rotate, driving the translation nuts (21) which, by means of the bearings (17 and 18), drive the two assembled cardan shafts (B), which begin to slide upwards in the two resistance columns (2 and 2' respectively), driving, by means of the bolt (15) and the shaft (13), the plates (24) on which the bed frames (C) are assembled; the upward movement will continue until one of the assembled cardan shafts (B) touches a connector, not shown in the drawings, to stop both electric motors (5) simultaneously. When lowering, the phenomenon is exactly the reverse: the threaded rods (9) turn in the opposite direction, forcing the assembled cardan shafts (B) to lower, also driving the bed frame (C).In the "lowered" position of the bed, due to gravity, the legs (30 and 31) stand upright, with the bed resting on them;When simultaneously operating the two electric motors (5), the feet (30 and 31) remain in the vertical position until near the end of the vertical stroke, when the claws (g and h) of the two levers (33 and 34, respectively) meet the thresholds (38 and 37, respectively) (fig.13.2, fig.13.4, fig.14.1 , fig.14.2), fixed on the resistance columns (2 and 2' respectively); the bed frame (C) continuing to move, the thresholds (38 and 37 respectively) act on the levers (33 and 34 respectively) and, by means of the thin bars (32), force the legs (30 and 31) to rotate and fold under the frame (27);On the way down, the phenomenon is exactly the opposite, the legs (30, 31) lowering into an upright position as soon as the bed starts to descend;2. Retractable bed with variable height system, according to claim 1 , characterized in that it can be provided with a device for positioning a work table (E) (fig.14.1, fig.14.2, fig.15.1, fig.15.2, fig.15.3, fig.15.4, fig.15.5, fig.15.6, fig.15.7) consisting of two identical L-shaped supports (39) slidingly inserted and fixed by means of equidistantly positioned bolts (50) (in the example of fig.4 and fig.8 only three bolts are shown, but they can be more, in order to be able to position the supports (39) symmetrically at different heights), between two identical strips (40), whose external dimension is so calculated that they can be assembled, in order, from bottom to top, on a lower axle(41) with rollers (42), on an intermediate axle (43) with rollers (42) and on two coaxial upper half-axles (44 and 45 respectively) with rollers (42); the half-axles (44 and 45) being so fixed that, when assembled, between the strips (40), the plates (24) can slide freely ; the supports (39) being assembled between the lower axle (41) and the intermediate axle (43) ; the rollers (42) assembled on the axles and half-axles being able to slide in the rolling recesses (d) (fig .9), arranged longitudinally and symmetrically in each of the resistance columns (2, respectively 2'); the supports (39) having several recesses (s) (fig.16) on the side facing the upper frame of the bed (25), with the function of adjusting the height of the work table according to the operator's height; in the 'lowered' position of the bed frame (C) (fig.14).1 ), the lower axle (41) with rollers(42) is not in the rolling recesses (d), the intermediate axle (43) with rollers (42) and the two coaxial upper half-axles (44 and 45 respectively) with rollers (42) being in the rolling recesses (d); to the outside of the belts (40) is mounted an assembly consisting of two identical blades (46), fixed at the bottom to a spacer (47) in which an indexing screw (48) can be inserted, and at the top, fixed by a pin (49) with rollers (42), which can be seated in the rolling seats (d) ; by using the indexing screw (48) on the spacer (47), the assembly of belts (40) with rollers (42) can be raised or lowered easily by sliding in the resistance columns (2 respectively 2'); on the two identical L-shaped supports (39), a horizontal plate, not shown on the drawing, can be mounted as a work table; with the simultaneous operation of the two motors (5), the two threaded rods (9) begin to rotate, driving the translation nuts (21) which, by means of the bearings (17 and 18), drive the two assembled cardan shafts(B), which begin to slide upwards in the two resistance columns (2 and 2' respectively), driving, by means of the bolt (15) and the shaft (13), the plates (24) on which the bed frames (C) are assembled; at a given moment, in the upward movement, the plates (24) engage in the recesses (n) of the axle (49) with rollers (42), forcing the rollers to slide upwards in the rolling recesses (d) arranged longitudinally and symmetrically in the resistance columns (2, respectively 2'); at the moment the indexing screw (48) reaches the first bolt (50) above it, it will start to drive the work table positioning device (E) upwards.The upward motion will continue until one of the assembled sled sleds (B) touches a connector, not shown in the drawings, for simultaneously stopping both electric motors (5).When lowering, the phenomenon is exactly the reverse: the threaded rods (9) rotate in the opposite direction, forcing the assembled cardan joint (B) to lower, also driving the bed frame (C) and the work table positioning device (E).

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