Piece of furniture for dental clinics comprising a practical system for slidably fixing an instrument-holder tray

Abstract

The present invention relates to a piece of furniture, preferably for dental clinics, comprising a practical system for slidably fixing a concealable instrument-holder tray. In particular, the system for moving the tray is simplified, more robust and it allows an easier hygiene with respect the prior art systems. Such advantages derive from a double support of the arm on two points with less cumbersome and more reliable means.

Description

“PIECE OF FURNITURE FOR DENTAL CLINICS COMPRISING A PRACTICAL SYSTEM FOR SLIDABLY FIXING AN INSTRUMENT-HOLDER TRAY”DESCRIPTIONTECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a piece of furniture, preferably for dental clinics, comprising a practical system for slidably fixing a concealable instrument-holder tray. In particular, the system for moving the tray is simplified, more robust and it allows an easier hygiene with respect the prior art systems.STATE OF THE PRIOR ART

[0002] In the furniture industry, especially for dental clinics, there are known systems in which a piece of furniture provided with an upper surface for working and placing various instruments, comprises a compartment or housing beneath said work surface adapted to allow the housing for an object-holder tray and for the support and movement mechanism thereof. Beneath said compartment, the piece of furniture may be completed by further surfaces defined by brackets and walls, and closed by door leaves or drawers for containing objects or instruments required by the physician or personnel designated to support the physician. Alternatively, the aforementioned compartment may be closed at the lower part by a panel of a bottom for separating the mechanism for moving the tray with respect to an underlying open space which may allow an operator to use the piece of furniture even as a desk and, therefore, be able to position the legs therein.

[0003] In particular, substantially there are two types of mechanisms for moving the tray. The first consists of an articulated arm fixed beneath the work surface and which can be extended so as to keep the tray always at a lower level with respect to the work surface. Generally, the arm therefore consists of a first segment with a first end rotatably fixed under the work surface and a second end which can be extended outside the work surface and provided with a flat articulation which allows the rotation of a first end of a second segment whose second end carries an object-holder tray fixed thereon through a further flat articulation which allows the rotation of the tray around itself.

[0004] This type of structure allows to move the tray along the work surface and allows to extend it at will far from the surface.

[0005] Despite being a good solution, it still reveals some drawbacks. As a matter of fact, the articulation of the arm does not allow the sliding of the tray parallel to the work surface but it allows limited positioning. Furthermore, the structure is complex to obtain, especiallyconsidering that the arm is fixed only at one point under the work surface and when the arm is extended it is required to ensure a sufficient resistance to the loads positioned on the tray. Therefore, the size and materials must be significant.

[0006] The second type of mechanism is represented by an arm which extends orthogonally to the edge of the work surface and it is fixed under the latter in a specific housing at the extraction or retraction opening of the arm, for example through a telescopic extension or a guide orthogonal to the work surface on which said arm slides. Simultaneously, the arm is also slidable along the work surface on a special further longitudinal guide fixed along said extraction and retraction opening. At the distal end of the arm with respect to the work surface there is then rotatably fixed the object-holder tray.

[0007] This structure allows the tray to be moved along the entire work surface. However, it should be observed that such movement is obtained through at least one track which extends along the opening of the compartment under the surface. On said track there is fixed the arm by means of suitable tracks and / or casters. The fixing must be sufficiently strong so as to allow a safe support not only of the arm but also of the instruments or various objects which are placed on the tray, when it is extended cantilevered away from the piece of furniture.

[0008] As a result, the construction of the track must provide for elements that are rather cumbersome or made of expensive materials so as to ensure the required strength. Furthermore, especially in environments like a dental clinic where hygiene is of primary importance, a structure with tracks / rails / casters unquestionably creates areas where dust accumulates and material residues deriving from processes, that are difficult to clean.

[0009] Basically, all of the solutions described above relating to a piece of furniture carrying an object-holder tray such as a peninsula which can be moved with respect to the work surface reveal drawbacks such to make the piece of furniture impractical and unsafe and weak, as well as unhygienic.

[0010] In addition, none of the solutions described above allow to adapt the position of the tray to different heights of the operators and it does not allow to lock the tray in extracted position against inadvertent impacts which could make the tray recede into its compartment under the work surface knocking down the instruments or materials placed thereon.SUMMARY OF THE INVENTION

[0011] Therefore, the technical problem underlying the present invention lies in designing a piece of furniture comprising an object-holder tray which can be moved with respect tothe work surface in a position that is safe and strong by means of a structure that is easy to operate and clean.

[0012] Such problem is overcome by a piece of furniture comprising an object-holder tray which can be moved with respect to the work surface of the piece of furniture by means of a longitudinal sliding mechanism, that is easy to obtain and safe.

[0013] Therefore, a first object of the present invention is to provide a piece of furniture provided with a particularly strong mechanism for moving an object-holder tray along the work surface.

[0014] A second object is a piece of furniture in which the sliding mechanism is supported in multiple points in a practical fashion without the need for complex, cumbersome and expensive supports.

[0015] A third object is a piece of furniture in which the sliding mechanism does not provide for particular hindrances in the proximity of the opening of the compartment for housing the tray.BRIEF DESCRIPTION OF THE FIGURES

[0016] Further characteristics and advantages of the piece of furniture comprising an object-holder tray which can be moved with respect to the work surface of the piece of furniture according to the present invention, are described below according to embodiments provided purely by way of non-limiting example and with reference to the figures below, wherein:- figure 1 shows a top and axonometric schematic view of a portion of the piece of furniture with the object-holder tray extracted from the work surface, according to the invention;- figure 2 shows a schematic bottom and axonometric view of the portion of the piece of furniture of figure 1 , without the bottom;- figure 3A shows a lateral schematic view of the portion of the piece of furniture of figure 1 in partial section;- figure 3B shows a cross-sectional view of a detail of figure 3A relating to a first end of an arm of an object-holder tray of the piece of furniture of the invention;- figure 3C shows a cross-sectional view of a detail of figure 3A relating to a caster for supporting an arm of an object-holder tray of the piece of furniture of the invention;- figure 4 shows an axonometric bottom schematic view of the portion of the piece of furniture of figure 1 , with the object-holder tray lifted;- figure 5A shows a lateral schematic view of the portion of the piece of furniture of figure 1 with an object-holder tray totally lowered and partially extracted from under the work surface of the piece of furniture;- figure 5B shows a partial cross-sectional lateral view of figure 5A with the tray fully extracted;- figure 6A shows a lateral and partial cross-sectional view of the piece of furniture of figure 4B with an object-holder tray in a lifting position;- figure 6B shows a lateral and partial cross-sectional view of the piece of furniture of figure 4B with the tray in a second lifting position;- figure 7A shows a lateral view of the piece of furniture of the invention with the object-holder tray extracted and in a third lifting position;- figure 7B shows a lateral view of the piece of furniture of figure 7A with the lifting mechanism of the tray in cross-section and a relevant enlargement;- figure 8A shows a lateral view of the piece of furniture of the invention with the object-holder tray extracted and in a fourth lifting position;- figure 8B shows a lateral view of the piece of furniture of figure 8A with the lifting mechanism of the tray in cross-section and a relevant enlargement;- figure 9A shows a cross-sectional lateral view of a detail of a mechanism for locking of the extension of the arm of the piece of furniture of the invention in a first condition;- figure 9B shows a lateral view of the detail of figure 9A with the locking mechanism in a second condition;- figure 9C shows a lateral view of the detail of figure 9A with the locking mechanism in a third condition;- figure 10 shows a lateral view of a portion of the piece of furniture with an objectholder tray extracted, in lifted position and provided with a lifting mechanism according to a second embodiment of the invention.DETAILED DESCRIPTION OF THE INVENTION

[0017] The idea underlying the present invention is to design a piece of furniture provided with an object-holder tray that is particularly strong and that is easy to operate and clean especially for use in fields in which hygiene is of crucial importance, like in dental clinics.

[0018] Bearing this idea mind, it was decided to strengthen the support of the arm which carries the object-holder tray and at the same time avoid complicating the structure for supporting and moving the arm.

[0019] Therefore, with reference to figures 1 and 2, the reference numeral 1 generally indicates a portion of the piece of furniture comprising a work surface 2 and an underlying box-like compartment 3. The compartment 3, and also the work surface 2 as a result, generally extends in a longitudinal direction so as to have two first 30 and second 31 larger sides, which are parallel and opposite which connect with two first 32 and second33 smaller sides, which are parallel and opposite. Therefore, preferably, the portion of the piece of furniture 1 is generally rectangular parallelepiped-shaped.

[0020] Furthermore, the compartment 3 comprises a bottom 34 opposite with respect to the work surface 2, an opening 35 on the first larger side 30 so as to allow the protrusion and longitudinal sliding of an object holder tray 4, while the second larger side 31 is preferably closed.

[0021] Advantageously, a longitudinal track 6 (figure 2) is fixed on the bottom 34 (not shown in figure 2) and parallel along and in proximity of the second larger side 31 . Then, on this track there is mounted an arm 5 in a position preferably orthogonal to the track. In particular, the arm 5 is telescopic with a first end 50 mounted on said track so as to allow the sliding of the arm orthogonally along said track 6, and therefore parallel along the opening 35. A second end 51 (figure 2) can instead be extended outside the compartment 3 through said telescopic mechanism.

[0022] Preferably, the first end 50 of the arm 5 comprises a pair of rollers 52 which are rotatably mounted on each of the two longitudinal sides of the arm. The rollers then engage corresponding longitudinal protrusions 61 obtained on the two opposite sides of the track 6 (figures 3A and 3B) so as to allow the sliding of the arm along said track.

[0023] Providing the track 6 far from the opening 35 of the compartment 3, allows to move the hindrances which cause an accumulation of dust and dirt and prevent an easy access to the compartment. This allows to further clear the opening, allowing a facilitated access to the compartment for cleaning.

[0024] In addition, as shown in figures 2, 3A and 3C, the arm 5 advantageously comprises a wheel 7 or caster rotatably fixed on the surface of the arm facing towards the bottom34 of the compartment 3 in proximity of the opening 35 of the compartment so as to allow the facilitated sliding of the arm throughout the opening, as well as a further point for resting on the bottom.

[0025] As a matter of fact, the advantage of this wheel lies in strengthening the arm 5 given that there is created a second point for resting on the bottom 34 besides the one obtained by the engagement with the track 6 fixed in proximity of the second larger side 31 of the compartment 3. Furthermore, the overall dimension of the wheel is significantlyminimal with respect to a track, like it instead happens according to the prior art. A further advantage consists in the possibility of the wheel to slide directly on the surface without the need for a sliding guide. As a result, both the cleaning and the access to the compartment may be advantageously increased, same case applying to the simplification of the structure.

[0026] According to a first variant of the present invention, the second end 51 of the arm 5 is fixed to said object-holder tray 4 by means of a lifting mechanism. According to a first embodiment, the lifting mechanism is an articulated quadrilateral 8 (figure 4). The quadrilateral is preferably a rectangle with four levers rotatably pivoted with a first end thereof on said second end 51 of the arm which protrudes from the compartment 3 under the work surface 2 of the piece of furniture, and with a second end thereof on said tray 4. In particular, the levers are pivoted two by two on two opposite sides of said arm 5 so as to achieve for each side of the arm a first lever 80 and a second lever 81 . The first lever 80 is rotatably constrained to the side of the arm 5 through a first end 80A, at the terminal edge of the second end of the arm 5, while a second end 80B is rotatably constrained to said tray 4 (figure 6A). The second lever 81 is rotatably constrained to the side of the arm 5 through a first end 81 A, far from said edge of the end of the arm, while the second end 81 B is rotatably constrained to said tray. Each second end 80B and 81 B of the first 80 and second 81 levers has a rounded profile which is connected on one side with a straight profile 80C, 81 C and on the other side with an inclined plane profile 80D, 81 D.

[0027] Preferably, the first 80 and second 81 levers are fixed to the tray by interposing a plate 9 which comprises a generally flat bottom 92 (figure 6A) and two side walls 90 (figure 4) which rise from said bottom substantially orthogonally and parallel to the arm 5. The bottom is fixed on the side of the tray opposite to the placing one and on each of the side walls there are pivoted the aforementioned first 80 and second 81 levers through the respective second ends 80B and 81 B (figure 6A). Preferably, the plate 9 also comprises a handle 91 for gripping and extracting the tray 4 from the compartment 3 or for the insertion thereof thereinto. Furthermore, preferably the bottom 92 of the plate may comprise grooves 93.

[0028] According to a second variant, the two first levers 80 and the two second levers 81 are connected by a bridge 10 facing towards the terminal edge of the arm (figure 4). Such bridge confers greater stability to the lifting mechanism. Furthermore, preferably, the surface of the bridge facing towards said terminal edge of the arm 5 is passed through by ribs 10A adapted to engage the aforementioned grooves 93 of the bottom of the plate 9. The advantage of said engagement is to make the coupling between the liftable part andthe fixed part more stable during the translation of the tray when lowered. Preferably, the respective surfaces may alternatively be made of soft material so as to make the endstroke more ergonomic, or combined with the engagement they also increase the stability between the two pieces.

[0029] As shown in figures 5-8, the use of the piece of furniture according to the present invention provides for the possibility of extracting the object-holder tray 4 from the compartment 3 under the work surface 2 by gripping on the handle 91 of the plate 9. Thanks to the aforementioned telescopic or guide structure, the arm 5 may be extended outwards therefore also moving the tray outwards (figure 5A). It should be observed that in this configuration the tray 4 is in the most lowered position and that is in the position in which the tray is almost in contact with the arm 5 and the first 60 and second 61 levers are substantially extended horizontally to the sides of the arm 5, each with the respective first end 80A, 81 A farthest from the work surface 2 with respect to the corresponding second end 80B, 81 B (figure 5B). Furthermore, in this configuration, the side walls 90 and the handle 91 of the plate 9 cover the articulated quadrilateral mechanism (figure 5A). In addition, the bottom 92 of the plate 9 rests against the aforementioned first straight profile 80C, 81 C of the levers (figure 5B). If present, the grooves 93 of the bottom of the plate 9 and the ribs 10A of the bridges 10, are in mutual engagement in this position.

[0030] Once the tray has been totally extracted, it can be lifted with respect to the arm 5 (figure 6A) so as to near the height of the work surface 2 and advantageously exceed its height so that it can freely rotate without colliding with the fixed surface of the piece of furniture, as shown in figure 6B. Such movement is carried out by gripping the tray and lifting it with a roto-translation movement moving away from the work surface 2. By so doing, the first 80 and second 81 levers rotate, pivoted on the arm 5, moving their respective second ends 80B and 81 B farther from the work surface 2. At the same time, the tray 4 is brought to a position that is farther from the surface with respect to the end edge of the arm 5.

[0031] In particular, as shown in figure 6A, when upon lifting the tray 4 exceeds the highest point, the first 80 and second 81 levers rotate bringing the inclined plane profile 80D, 81 D towards the bottom 92 up to obtaining an abutment against the bottom (figure 6B) so as to lock the tray 4 in the operative lifted position.

[0032] In order to position the tray in the lowered position and allow the reinsertion thereof into the houses 3, it will be sufficient to carry out a reverse roto-translation with respect to the one just described above.

[0033] According to a second embodiment, as shown in figures 7 and 8, the articulated quadrilateral lifting mechanism 8 comprises an element 11 for adjusting the height of the object-holder tray 4 (figure 7B). This element advantageously allows to position the tray 4 at at least one height of the arm 5 that is different with respect to the position that it can take from the aforementioned direct engagement with the levers. This allows to obtain maximum adaptability to the needs of the operators and, as a result, this increases the ergonomics of the work station.

[0034] In particular, as shown in figure 7A, one of the two side walls 90 of the plate 9 is provided with a selector 12 which controls the aforementioned adjustment device 1 1 to move it between the bottom 92 of the plate and at least one of the aforementioned first 80 or second 81 levers in at least one lifting operative position. Preferably, the adjustment element 1 1 (figure 7B) is a wedge having a first surface 1 1 A for sliding and engaging on the surface of the tray 4 opposite to the one for placing the objects and a second surface 11 B for engagement with one of the first 80 and second 81 levers, preferably with the first lever 80 as reported in figure 7B. More preferably, the first surface 1 1 A slides on the bottom 92 of the plate 9. In particular, the second surface 1 1 B is inclined with respect to the first surface 1 1 A forming a ramp with a downward development moving away from the arm 5.

[0035] Figures 7A and 7B show a first lifting condition is shown which exploits the locking of the tray 4 in a first position by engaging the above-mentioned inclined profiles 80D and 81 D, respectively of the first 80 and second 81 levers, and the bottom 92 of plate 9.

[0036] In order to obtain a second lifting condition, which is higher than the first, it will suffice to lift the tray by roto-translating it in the reverse direction, that is approaching the work surface 2, returning to a position substantially like the one shown in figure 6A. At this point, the inclined profiles 80D and 81 D are freed from the bottom 92 and, as shown by the arrow in figure 8A, the selector 12 can be moved towards the handle 91 so as to move the wedge 1 1 between said bottom and at least one of the inclined profiles, for example the second surface 80D of the first lever 80 (figure 8B). In this position, the ramp of the second surface 10B of the wedge abuts against the inclined profile 80D, while the first surface 10A remains abutting against the bottom 92 of the plate 9.

[0037] According to a further embodiment of the invention, as shown in figures 9A-9C, the system for moving the object-holder tray 4 also comprises a mechanism 12 for reversibly locking the extracted position of the arm 5. This mechanism advantageously allows to maintain the arm stationary not only when lowering the tray 4, but it also allows to preventinadvertent impacts from pushing the tray towards the work surface 2 knocking down the objects placed thereon.

[0038] In particular, the locking mechanism 13 comprises a tooth 14 protruding from the lower surface 53 of the arm 5, that is the surface facing towards the bottom 34 of the compartment 3 (not shown in figure 9), so as to abut against the opening edge 35 of the compartment when the arm is extracted and the tray 4 is fully outside. Advantageously, the tooth is automatically activated upon removing the arm and it remains in locking position until it is deactivated manually.

[0039] As a matter of fact, as explained above, the arm 5 is slidably mounted on a track 6 fixed on the bottom 34 of the compartment 3 under the work surface 2 (figure 3A). The lower surface 53 of the arm 5 comprises a seat 54 in which the tooth 14 is housed (figure 9A). This tooth at least partly elastically protrudes from said seat and it can be retracted totally when the arm 5 transversely traverses the opening 35 both towards the extraction and towards the retraction in the compartment 3.

[0040] Preferably, the tooth 14 comprise a first end 14A that is pivoted and totally housed in said seat 54 towards the part closest to the opening 35, and a second end 14B free to protrude with respect to the seat 54. Between said first and second end, there is fixed an elastic element 15 which maintains the second end 14B of the tooth 14 protruding from the lower surface 53 of the arm 5. This configuration allows to create an inclined plane of the tooth 14 having the inclination towards the opening 35 of the compartment 3.

[0041] As shown in figure 9A, when the arm 5 is extracted from the compartment 3, the locking tooth 14 protrudes from the lower surface 53 until it abuts against the inner edge 35A of the opening 35, that is the side facing towards the internal of the compartment 3. Given that the first end 14A is inside the seat 54 of the lower surface 53 of the arm 5 and the inclined plane progressively protrudes as it proceeds towards the second end 14B, the aforementioned extraction is facilitated by the guide element created by the development of the inclined plane. Sliding transversely to the track to extract the tray 4, also the second end 14B of the tooth 14 is pushed into the seat 54 (figure 9B) overcoming the thrust force of the elastic element 15.

[0042] Once the outer edge of the opening 35B has been overcome transversely (figure 9C), the second end 14B is once again free to protrude from the seat 54 under the thrust of the elastic element 15. At the same time, the tray 4 is totally outside the compartment 3 of the piece of furniture and far from the perimeter edge of the work surface 2, so that it can be freely lifted and positioned at the desired height as explained above.

[0043] Advantageously, with the position taken in figure 9C, the tray 4 may be moved along the work surface or it may be lowered without the drawback of moving in an unwanted fashion toward the inside of the compartment 3. As a matter of fact, now the second end 14B abuts against the outer edge 35B of the opening 35. This condition blocks the aforementioned unwanted movement toward the inside of the compartment.

[0044] It should be observed that once there no longer arises the need for the objectholder tray 4, the latter can once again be positioned in the compartment 3 under the work surface 2 by simply pressing the tooth 14, preferably near its second end 14B, so as to overcome the force of the elastic element 15 and make it recede into the seat 54. Now, the object-holder tray 4 can be pushed into the compartment.

[0045] According to a further embodiment of the invention, the lifting of the object-holder tray 4 may be obtained with a pantograph mechanism 16, as shown in figure 9. In this different solution, two articulated levers (not shown) for each side of the arm 5 are connected to each other in a cross-like fashion by a rotation pin (not shown) and the respective ends are connected on one side to the second end 51 of the arm and on the other side to said tray 4. A cam system (not shown) also allows to reversibly lock the pantograph lifting levers.

[0046] In the light of the above, it is clear that the drawbacks of the prior art mentioned above have been overcome and significant advantages have been achieved.

[0047] Firstly, the problems relating to hindrances on the opening which allows the extraction of the object-holder tray have been overcome. Furthermore, the possibility of cleaning the compartment for containing the tray was improved.

[0048] It should be observed that by moving the sliding track of the arm carrying the object-holder tray far from the opening, one can increase the space for access into the compartment. In addition, providing a caster for resting on the part proximal to the opening, allows to simplify the support structure while increasing the strength thereof. As a matter of fact, now there are two points for supporting the arm, one at the opposite side with respect to the opening and one at the opening, as explained. This also entails that the track may be small in size specifically due to the fact that it is assisted by the caster, therefore allowing to save material and related costs.

[0049] In addition, now the tray may be lifted in the object holder position or lowered so as to be positioned under the work surface when not being used.

[0050] The safety of the operators also is increased by locking the extracted position of the tray which, therefore, allows the operator to always have objects and tools always within reach even in case of emergencies.

[0051] Furthermore, the lifted position may take various heights so as to meet various needs. As a matter of fact, not only can the tray be positioned above the work surface, but it can also be positioned at different heights so as to adapt to any operator. As a result, the ergonomics of the working position for an operator, such as for example a dentist, a dental technician or a dental hygienist, is optimised and, at the same time it allows for great practicability.

[0052] Numerous variants of the work furniture comprising a movement mechanism for an object-holder tray according to the present invention may be adopted by the person skilled in the art, without departing from the scope of protection as defined by the attached claims.

[0053] For example, the object-holder tray may be connected to the underlying plate through a rotary engagement which allows them to rotate for a fine positioning with respect to the operator. The shapes and sizes of the individual elements which form the piece of furniture may vary depending on the specific needs or preferences.

[0054] The reversible locking mechanism of the extracted position of the arm 5 described for articulated quadrilateral lifting of the tray may also apply to the pantograph variant.

Claims

CLAIMS1. Work furniture comprising a work surface (2), a compartment (3) underneath said work surface and an object-holder tray (4) capable of being alternatively housed in said compartment or extracted therefrom by means of an arm (5) which is extendable and sliding with respect to the work surface (2), wherein said compartment (3) comprises a bottom (34), a first larger side (30) provided with an opening (35) which extends longitudinally under said work surface (2) to allow the extension of said arm (5), and a second larger side (31 ) opposite said first side, characterised in that said first side (30) of the compartment (3) comprises a track (6) arranged parallel to said opening (35) and on which a first end (50) of the arm (5) is slidably fixed, and said arm comprises a wheel (7) or caster which allows it to slide easily resting on the bottom (34) of the compartment (3) in the vicinity of and along said opening (35).

2. Work furniture according to claim 1 , wherein said arm (5) is extendable orthogonally with respect to said track (6) and comprises a second end (51 ) suitable for being alternatively extracted and retracted inside said compartment (3), said second end comprising said object-holder tray (4).

3. Work furniture according to claim 1 or 2, wherein said object-holding tray (4) can be lifted from said arm (5) by means of a lifting mechanism (8, 15) to be positioned outside the compartment (3) at at least one height with respect to said work surface (2) and reversibly locked there.

4. Work furniture according to claim 3, wherein said lifting mechanism (8) is an articulated quadrilateral comprising four levers (80, 81 ) rotatably pivoted with a first end (80A, 81 A) thereof on said second end (51 ) of said arm (5), and with a second end (80B, 81 B) thereof on said tray (4).

5. Work furniture according to claim 4, wherein said first (80) and second (81 ) levers are fixed to the tray (4) by means of the interposition of a plate (9) comprising a generally flat bottom (92) and two side walls (90) which are raised from said bottom substantially orthogonally and parallel to the arm (5), the bottom being fixed on the side of the tray opposite to the support side and said first (80) and second (81 ) levers being hinged on each of the side walls by means of their respective second ends (80B) and (81 B).

6. Work furniture according to claim 5, further comprising an element (1 1 ) for adjusting the height of the object-holder tray (4) consisting of a wedge having a first sliding surface (1 1 A) for engaging with the surface of the tray (4) opposite to that on whichthe objects rest, or on the bottom (92) of the plate (9), and a second surface (1 1 B) for engaging with one of the first (80) and second (81 ) levers, the second surface (1 1 B) being inclined with respect to the first surface (1 1 A) forming a ramp with a downward trend away from the arm (5).

7. Work furniture according to claim 6, further comprising a selector (12) which controls said adjusting element (1 1 ) to move it between the bottom (92) of the plate (9) and at least one of said first (80) and second (81 ) levers.

8. Work furniture according to any one of claims 1 to 7, further comprising a mechanism (13) for reversibly locking the extracted position of the arm (5) comprising a tooth (14) elastically protruding from the lower surface (53) of the arm (5) so as to abut against the external edge (35B) of the opening (35) of the compartment (3), when the arm is extracted from the compartment (3).

9. Work furniture according to claim 8, wherein said tooth (14) comprises a first end (14A) pivoted and totally housed in a seat (54) obtained on the lower surface (53) of the arm (5), the tooth also comprising a second end (14B) free to alternatively protrude or retract into the seat (54), between said first and second ends being then fixed an elastic element (15) which keeps the second end (14B) of the tooth (14) protruding from the lower surface (53) of the arm (5) when the tooth is free.

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