Hinging device for security enclosure door

Abstract

 @ The water-tight door 10 of a safe or strongroom is hung on two double-articulated hinges 12,13 (Figure 1). Each hinge includes an intermediate element 18,18A connected by a pivot pin 19,19A to a mounting block 16,16A on the door frame 11, and also connected by a pivot pin 20,20A to a second block 17,17A on the door itself. This articulated connection permits, firstly, swinging of the door about the axis of the pins 19,19A when it is opened and closed. Secondly when closed the door is clenched inwards against a sealing strip 52 by throwing a series of tapered bolts 54 (Figure 3), in so doing the intermediate hinge elements 18,18A turning slightly relative to the door about the pins 20,20A. In the upper hinge 12 a compensation spring 40 (Figure 5) acts between the intermediate element 18 and the door block 17 so as to keep these parts rotated relative to one another in the direction opposite to the relative rotation performed during clenching. By this means the tendency of the door to twist under its own weight on the double hinges is resisted.

Description

[0001] The subject of the present invention is a hinging device for hinging the watertight door of a safe, strong-room or the like security enclosure.

[0002] Known doors of this kind are hinged with the fixed frame normally by means of two hinges, an upper hinge and a lower hinge, and provision is made for a system of bolts which can be operated by an external hand-wheel so as to clench the door, in its closed position, against a circumferential shoulder provided with a seal in the seating of the fixed frame.

[0003] Where normal hinges with a single hinging axis are used, the drawback exists that, during the last part of the rotational movement of the door, during closing, when the latter enters the seating of the frame and moves towards the sealing strip, and also during the first part of the rotational movement of the door, during opening, when the latter moves away from the sealing strip and leaves its seating, relative frictional movements occur between the seal and door on the hinging side and these lead to deformation and irregular compression of the seal and consequent rapid wear of the same.

[0004] In order to overcome this drawback, the use of special double hinges to connect the door to the frame has already been proposed. These double hinges each consist of three elements which are articulated with each other by means of two pins, one being fixed to the door, another being fixed to the frame and the third connecting the first two. As a result of these double hinges, the door is able to perform its normal rotational movement, during opening and closing, about the axis of the first pin articulating the element fixed to the frame with the middle element and, moreover, the door is able to move towards or move away from the sealing strip in the seating of the frame, during which latter movement the door remains parallel to itself and performs a slight rotation about the axis of the second pin articulating the element fixed to the door with the middle element. In this way, starting from the open position of the door, the Latter, with its rotational movement about the axis of the first articulation pin, can be made to ente- the seating of the frame, without however being pressed against the sealing strip yet, whereas, with the approaching a movement caused by closing of the system of bolts, the door is simply displaced, parallel to itself, so as to be pressed frontally against the seal, without relative rubbing occurring between the door and seal. The same applies, obviously with the movements occurring in the reverse order, when the doer is opened. Any harmful rubbing and hence premature wear of the sealing strip is thus prevented.

[0005] However, owing to the excessive weight of coors of this kind and the fact that their centre, of gravity is far removed from the hinging axis of the middle elements of the double hinges, in the case of such a hinging device the problem arises of having to counteract the tendency of the door to assume an inclined position, relative to the vertical, when it is not pressed inside the seating of the fixed frame, leaning backwards at the top and forwards at the bottom, relative to the plane in which the hinging axes lie.

[0006] In order to solve this problem, it was proposed that a rigid strut connecting the middle elements of the two three-element double hinges should be provided, in order to counteract the said tendency of the door to lean. This connecting strut must be strong and hence heavy enough to absorb the stresses to which it is subjected and, as a result, increases considerably the overall weight of the door, in addition to constituting an unattractive bulky element visible on the front of the door itself.

[0007] The object of the present invention is mainly to provide a hinging device for the sealed door of a safe, strong-room or similar object, of the type comprising two double hinges, an upper hinge and a Lower hinge, which elimi- _nates the need for a strut connecting the middle elements of the two double hinges in order to counterbalance the weight cf the door. Another object of the present invention is to provide such a hinging device which has a simple and economical structure and which is, in particular, less heavy than the known devices and aesthetically more acceptable. Another object of the invention is to provide a hinging device of this type, in which only tne upper couble hinge is designed to carry the entire weight of the door and in which. this weight is borne mainly by the pin of this hinge articu- l_ating the element fixed to the frame with the middle element, which pin is provided with means for adjusting the height of the door.

[0008] The hinging device according to the invention, in its most general form, is characterised in that its upper double hinge incorporates an equaliser spring acting between the element fixed to the door and the middle element of the hinge itself, the said spring being arranged at a distance from the pin articulating these two elements so as to keep them mutually rotated in a position where bearing surfaces with which the elements themselves are provided are in mutual contact. Owing to the presence of this equaliser spring in the upper double hinge, the tendency of the door to lean backwards at the top, relative to the vertical plane, under the effect of its weight applied eccentrically, is counteracted. Obviously, there is no need to provide a similar spring in the lower double hinge, since the actual weight of the door keeps the bearing surfaces of the element fixed to the door and of the middle element of the Lower double hinge, in mutual contact, at the bottom.

[0009] The equaliser spring incorporated in the upper double hinge is preferably lccateà inside a seating which is provided in the middle element and is accessible from the outside and can be covered with a cap; a threaded pin, which is screwed into the hinge element fixed to the ooor, penetrates with play into the said seating, the spring being arranged coaxially, relative to the said pin, between the head of the latter and a shoulder of the said seating.

[0010] Advantageously, the preloading of the equaliser spring can be adjusted in accordance with the weight of the door, by screwing or unscrewing the said pin in the hinge element fixed to the door.

[0011] The equaliser spring incorporated inside the upper double hinge does not prevent the slight rotation about the axis of the second pin articulating the element fixed to the door with the middle element of the hinge when the door moves towards or away from the sealing strip provided in the fixed frame.

[0012] Since the entire weight of the door bears on the upper double hinge and since it is desirable to shift this weight mainly onto the pin of this hinge articulating the element fixed to the frame with the middle element, so as to be-able to Lighten the second articulation pin, the invention provides for the insertion, between the facing horizontal bearing surfaces of the element fixed to the door and of the middle element, of sliding blocks with rollers arranged on the arcs of circles, the centres of which lie on the axis of the said second articulation pin. In this way, during the said slight rotation of the element fixed to the door and the middle element of the upper double hinge relative to each otner, the weight of the door is transferred mainly onto the middle element and hence onto the articulation pin which connects the latter to the element fixed to the fixed frame.

[0013] Conversely, ordinary sliding blocks made of anti-friction material can be inserted in the Lower double hinge which does not bear the weight of the door, between the horizontal facing surfaces of the element fixed to the door and of the middle element.

[0014] These and other characteristic features of the hinging device according to the invention and the associated advantages will emerge more clearly from the following detailed description of an example of embodiment, with reference to the attached drawings in which:

Figure 1 is a schematic view, in elevation, of the exterior of a door connected to a fixed frame by means of the hinging device, the door being in a closed position,

Figure 2 is a cross-section along the broken line II-II shown in Figure 1, with the door already inserted in the seating of the frame, but not yet pressed against the sealing strip.

Figure 3 is a view similar to that of Figure 2, but with the door pressed against the sealing strip in the seating of the frame,

Figure 4 shows the upper double hinge only, in vertical section along the broken line IV-IV shown in Figure 5,

Figure 5 is a cross-section of the upper double hinge only, along the line V-V shown in Figure 4,

Figure 6 is a partial cross-section along the line VI-VI shown in Figure 4,

Figure 7 shows the lower double hinge only, in vertical section along the broken line VII-VII shown in Figure 8,

Figure 8 is a cross-section along the line VILI-VIII shown in Figure 7, and

Figure 9 is a partial cross-section along the line IX-IX shown in Figure 7.

[0015] Figure 1 shows, in schematic form, a sealed door 10, of a safe for example, connected to the fixed frame 11 by means of a hinging device which comprises an upper double hinge and a lower double hinge generally indicated by 12 and 13, respectively. A system consisting of four latches, which is indicated generally by 14 and can be operated in a manner known per se by means of a hand wheel 15, presses and locks the door 10 in a closed position in its seating in the fixed frame 11 so that, in this position, the external surface of the door 10 is flush with the front surface of the frame 11.

[0016] With reference now to Figures 4 to 6 in particular, the upper double hinge 12 of the hinging device will be described in detail. This hinge comprises an element 16 fixed to the frame 11, an element 17 fixed to the door 10, as well as a middle element 18 connecting the two elements 16 and 17. The middle element 18 is connected to the element 16 fixed to the frame 11, by means of an articulation pin 19, whereas the element 17 fixed to the door 1D is connecteo to the middle element 18 by means of a pin 20, the axes of the pin 19 and of the pin 20 being vertical and parallel.

[0017] It should be noted that the middle element 18 has a cavity 21 which is open towards the door 10 and towards that end of the element which is opposite that used for connection to the element 16 fixed to the frame 11, the said cavity 21 being designed to receive the element 17 fixec to the door 10. The bottom wall 22 of the cavity 21 of the middle element 18 constitutes a shoulder which, together with the front surface 23 of the element 17, which surface is opposite the surface of the said element in contact with the door 10, limits in one direction mutual rotation of the elements 17 and 18 of the hinge, about the axis of the pin 20.

[0018] The upper and lower horizontal surfaces 24 and 25, respectively, of the cavity 21 are preferably covered with tempered-steel foil and, when the element 17 fixed to the door 10 is inserted in the cavity 21 (see Figure 4), face upper and lower horizontal surfaces 26 and 27, respectively, of the element 17 which are also covered with tempered-steel foil. SLiding blocks 28 and 29, respectively, are inserted between the respective facing surfaces 24, 26 and 25, 27 (see in particular Figure 6 which shows the lower sliding block 29) and are provided with elongated apertures located on radii passing through the axis of the pin .20 and arranged on the arcs of circles, the centres of which lie on the axis of the said pin, as can be clearly seen in Figure 6, each aperture being designed to receive a sliding roller 30 made of tempered steel. Those apertures for the rollers 30 which are arranged on the arcs of circles with a greater radius are closer to each other. Retaining strips 31, 32 fixed to the middle element 18 of the hinge keep the said sliding blocks with rollers in position. The pin 20 articulating the element 17 and the middle element 18 of the hinge is located inside aligned holes in the two elements and this pin is fixed relative to the middle element 18, whereas it can be rotated, relative to the element 17 fixed to the door 10, in a bushing 33 arranged inside the relevant through- hole. Moreover, provision is made for an upper thrust bearing 34 and lower thrust bearing 35 through which the pin 20 passes and which are arranged between the surfaces 24 and 25 of the cavity 21 of the element 18 and the seating 26a, 27a provided in the element 17.

[0019] The pin 19 articulating the element 16 and the middle element 18 of the hinge is arranged inside aligned holes in these two elements and this pin is Locked in position by means of a grub screw 36 in the hole of the middle element 18, whereas it is mounted rotatably by means of a taper roller bearing 37 in the hole of the element 16 fixed to the frame 11. An adjusting screw 38, which is accessible from the exterior and can be locked in position by means of a grub screw 39, is screwed into the middle element 18 coaxially relative to the articulation pin 19 and is used to adjust the height of the middle element 18 and hence of the entire door 10 in relation to the element 16 and hence in relation to the fixed frame 11, the said screw 38 in fact applying pressure against the upper end of the pin 19.

[0020] It must be noted that the upper hinge 12 is intended to bear the entire weight of the door, its element 16 fixed to the frame 11 being arranged lower than the mobile middle element 18, whereas, in the case of the Lower hinge 13, the element fixed to the frame 11 is arranged above the mobile middle element. On account of the design described above and precisely on account of the sliding blocks 28 and 29 with rollers provided between the middle element 18 and the element 17, fixed to the door 10, of the upper hinge, the weight of the door 1D is transferred mainly onto the pin -19 articulating the middle element 18 with the element 16 fixed to the frame 11, which pin 19 is obviously of a suitable size, whereas the pin 20 articulating the middle element 18 of the upper hinge with the element 17 fixed to the door 10, since it is not substantially stressed by the weight of the door, can be made suitably lighter, as is clearly visible in Figure 4.

[0021] With reference now to Figure 5, the means for compensating the weight of the door will be described; these means are arranged so as to counteract the tendency for the said door to assume a position which, relative to the vertical, is inclined backwards at the top and forwards at the bottom, on account of the eccentricity of its centre of gravity. These means consist substantially of a helical equaliser spring, which is indicated by 40 and which operates between the elements 17 fixed to the door 10 and the middle element 18 of the upper double hinge 12.

[0022] In particular, a screw pin 42 with an enlarged head 43 is screwed into a threaded hole 41 in the element 17. When the elements 17 and 18 of the hinge are assembled, this pin 42 penetrates through a hole 44 into a seating 45 provided in the middle element 18. It must be remembered that the hole 44 has a Larger diameter than the external diameter of the pin 42 thus creating sufficient play to allow the element 17, from which the pin 42 protrudes, and the middle element 18 into the seating 45 of which the pin 42 penetrates, to rotate relative to each other within the limits laid down for operation. The bottom part of the seating 45 forms a support shoulder for the helical spring 40 which is arranged coaxially around the pin 42 and which rests with its other end, via a washer 46, against the head 43 of the pin 42. The seating 45 can be covered with a cap 47. By removing this cap and acting on the head 43 of the pin 42, the latter can be screwed or unscrewed in the threaded hole 41 of the element 17 so as to adjust preloading of the spring 40 in accordance with the weight of the door 10.

[0023] It is obvious how, owing to the action of the equaliser spring 40, the hinge element 17 fixed to the door 10 is kept rotated, relative to the middle element 18, about the axis of the pin 20 in a position in which the front surface 23 of the element 17 bears against the bottom wall 22 of the cavity 21 provided in the middle element 18 of the hinge, as is visible in Figure 5. In this manner, the door 10 is kept in a vertical position, thus counteracting its tendency to lean backwards at the top.

[0024] Obviously, the spring 40 does not prevent the two hinge elements 17 and 18 being rotated in an opposite direction relative to each other by applying a suitable force, as will be described below.

[0025] with reference to Figures 7 to 9, the lower double hinge 13 of the hinging device will now be described.

[0026] In this respect it must be remembered that the Lower double hinge 13 is substantially identical to the upper double hinge 12 and can be made using the same component parts. Therefore, the elements in the lower hinge 13 which correspond to similar elements in the upper hinge 12 are indicated by the same reference numbers, followed by the Letter A.

[0027] The Lower double hinge 13 also consists of an element 16A fixed to the frame 11, an element 17A fixed to the door 10 and a middle element 18A with a cavity 21A into which the element 17A enters. A pin 19A connects the elements 16A and 18A and a pin 20A connects the elements 17A and 18A. As already mentioned, the element 16A of the Lower hinge 13, which is fixed to the frame 11, is located above the middle element 18A, and hence the Lower hinge is not designed to bear the weight of the door 10. For this reason, the Lower hinge is provided, in place of sliding blocks with rollers, with ordinary sliding blocks, 28A and 29A, which are made of anti-friction material and are Located between the horizontal surfaces 24A and 25A, respectively, of the cavity-21A provided in the middle element 18A, and the surfaces 26A and 27A , respectively, of the element 17A. The thrust bearings are also not required between the elements 17A and 18A, and the pin 19A, as well, is mounted in ordinary bearings Located inside the element 16A. Moreover, the adjusting screw 38 provided in the upper hinge 12 is not present.

[0028] In addition, the equaliser spring is not required in the Lower hinge 13, since the front surface 23A of the element 17A is kept pressed against the bottom wall 22A of the cavity 21A provided in the middle element 18A by tne tendency of the door 10 to assume a position which is inclined forwards, at the bottom, relative to the vertical. In any case, as regards economy of the hinging device, it is of interest that the two hinges can be made using the same component parts.

[0029] with particular reference to Figures 2 and 3, operation of the hinging device for a sealed door will now be described.

[0030] It can be seen that the fixed frame 11 has an opening 50 which forms a seating suitable for receiving the door 10. This opening 50 is provided with a circumferential shoulder 51 carrying a circumferential front seal 52, towards which the door 10 is intended to move and against which it is intended to be pressed with one of its rear shoulders 53:

[0031] Figure 2 shows the door 10 in a position where it has already entered the opening 50 of the fixed frame 11 and is located next to the seal 52, without however being pressed against the latter. Rotation of the door 10 from the open position into the position shown in Figure 2 is performed about the aligned vertical axis of the articulation pins 19 and 19A of the upper double hinge 12 and lower double hinge 13. In all the intermediate positions between these two extreme positions (and including the Latter), the door 1D is kept vertically erect by the action of the equaliser spring 40, and the elements 17 and 18 of the upper hinge 12 along with the elements 17A and 18A of the Lower hinge 13 are kept rotated relative to each other, in a position where their surfaces 22 and 23 and 22A and 23A, respectively, rest against each other.

[0032] From the position shown in Figure 2, the door 10 is moved into the position shown in Figure 3 by operating in a known manner, by means of the hand wheel 15, the system of latches 14. During this movement, the door remains parallel, relative to itself, and this movement is enabled by a slight rotation of the hinge element 17, 17A fixed to the door, relative to the middle elements 18, 18A of the two hinges 12, 13. In the upper double hinge 12, this rotation is performed against the action of the equaliser spring 40.

[0033] During the compressive movement of the door 10, the sealing strip 52 is compressed by means of the rear shoulder 53 of the door itself, without rubbing occurring between the door and the seal.

[0034] The system of latches which causes the compressive movement of the door 10 comprises four latches, two on the hinging side and two on the free side of the door. The four latches are identical to each other and one of them is shown in cross section and in. two different positions in Figures 2 and 3.

[0035] The latch shown is indicated generally by 54 and consists of a plate 55 fixed to the end of a rod 56 providing a connection to the central operating mechanism, the said plate being guided in a block 57, fixed to the door 10, so as to perform rectilinear movements in a plane parallel to the external surface of the door. The plate 55 has an end-piece 58 with opposite working faces inclined towards the door relative to the plane in which the plate 55 moves inside the guide block 57. The inner face of the end-piece 58, which faces the door 10, has a step formed by a depressed part. Another block 59 is fixed to the frame 11, opposite the block 57, and this block 59 has a cavity 60 intended to receive the end-piece 58 of the plate 55. This cavity 60 has a first inclined wall designed to cooperate with the outer face of the end-piece 58 and a second inclined wall which is located opposite and forms a step with a projecting part designed to cooperate with the inner stepped face of the said end-piece, the said first wall of the cavity 60 ending at a point located further forward than the second wall, relative to the direction in which the end-piece 58 is introduced into the cavity 60. With the movement of the latch 54 from its retracted position in which the door 10 is unlocked, a movement which occurs in a rectilinear direction inside the guideblock 57 and which is controlled by the central operating mechanism via the rod 56, initially the first more projecting part of the inner stepped face of the end-piece 58 comes into contact with the projecting part of the second stepped wall of the cavity 60 inside the block 59 (see Figure 2) and, owing to the inclined nature of the surfaces in contact with each other, a first compressive movement of the door 10 occurs. ImmediateLy afterwards, the outer face of the end-piece 58 also comes into contact with the first inclined wall of the cavity 60 inside the block 59 and hence the door 10 is further moved, compressing the sealing strip 52 (see Figure 3). When the latch 54 is in the fully engaged position shown in Figure 3, the outer face of its end-piece remains in contact with the corresponding inclined wall of the cavity 60 inside the block 59, while a small gap is created between the inner stepped face of the end-piece 58 and the corresponding stepped wall of the cavity 60 inside the block 59. It is thus the first inclined wall of the cavity 60 inside the block 59 which, by acting on the outer face of the end-piece 58 of the latch 54, keeps the door 10 pressed inside the opening 50 of the frame 11. However, if the door 10 were to be subjected to an unexpected external compressive force resulting, for example, from the impact of a mass of water, shock wave or similar, the door 10 is able to yield slightly and hence further compress the seal 52, on account of the play exist- i_ng between the inner stepped face of the end-piece 58 and the corresponding stepped wall of the cavity 60 inside the block 59, thus further increasing the sealing effect of the door 10. This advantageous feature could not be achieved if, when the latch is in the fully engaged position, both the faces of its end-piece were in contact with the relevant walls of the cavity inside the block fixed to the frame.

[0036] In place of the block 59 fixed to the frame 11, another element could be used, which is still fixed to the frame 11, but which has two rollers which are located opposite each other and at a suitable distance from each other and which are designed to receive between them the end-piece 58 of the latch. In this case, the said rollers perform the function of the opposing walls of the cavity 60 inside the block 59 and cooperate with the opposite faces of the end-piece 58 of the latch 54, thereby creating a rolling friction, instead of a sliding friction, between the cooperating surfaces.

[0037] The hinging device according to the invention has been described and illustrated with regard to hinges arranged on the right-hand side, but it is obvious that the hinges using the same component parts could also be arranged on the left-hand side.

[0038] As is clear from the above description, the hinges forming the hinging device are simple in structure, relatively small in size and, since the strut connecting the middle elements is dispensed with, the overall weight is .considerably reduced and the aesthetic appearance substantially improved.

Claims

₁. Hinging device for the sealed door of a safe, strong- room or similar object, in which the door, in its closed position, is -inserted into the opening of a fixed frame and is pressed frontally, by means of a system of latches, against a circumferential seal Located on a shoulder inside the said opening, comprising an upper hinge and a lower hinge, both of these hinges being double hinges with three elements connected to each other by means of articulation pins, one element being fixed to the frame, the second element being fixed to the door and the third middle element connecting the two first elements, characterised in that the upper double hinge incorporates an equaliser spring acting between the element fixed to the door and the middle element, the said spring being arranged at a distance from the pin articulating these two elements, so as to keep them rotated relative to each other in a position in which the bearing surfaces with which the elements themselves are provided are in contact with each other.

2. Device according to Claim 1, characterised in that the said equaliser spring is located in a seating provided inside the middle element of the upper double hinge, in that a pin which is fixed to the hinge element integral with the door and has an enlarged head penetrates with play into the said seating, and in that the spring is arranged coaxially about the said pin, between the head of the Latter and a shoulder of the said seating.

3. Device according to Claim 2, characterised in that the said seating is accessible from the outside and can be covered with a cap and in that the said pin is screwed, in an adjustable position, into a threaded hole in the element fixed to the door.

4. Device according to Claim 1, characterised in that, in the case of the upper double hinge, the element fixed to the frame is arranged below the associated middle element and in that, in the case of the Lower double hinge, the element fixed to the frame is arranged above the associated middle element.

5. Device according to Claim 4, characterised in that the middle element of each hinge has a cavity designed to receive the element fixed to the door, the said cavity being open towards the door and towards that end of the middle element which is opposite that used for connection to the element fixed to the frame, the bottom wall of the said cavity and that wall of the element fixed to the door which is opposite that in contact with the door constituting the said bearing surfaces.

6. Device according to Claim 5, characterised in that sliding blocks are arranged between the upper and Lower surfaces of the said cavity provided in that middle element of each hinge and the associated facing surfaces of the element fixed to the door and engaged in the said cavity.

7. Device according to Claim 6, characterised in that the sliding blocks of the upper double hinge consist of sliding blocks with rollers, the rollers being located in apertures which are arranged radially in relation to the axis about which the element fixed to the door and the middle element rotate relative to each other.

₈. Device according to Claim 7, characterised in that the said rollers are located in radial apertures of the sliding blocks arranged on the arcs of circles, the centres of which lie on the said axis of rotation.

9. Device according to Claim 8, characterised in that the apertures arranged on the circle arcs furthest from the axis of rotation are closer to each other than the aper- _tures arranged on the circle arcs closest to the.axis of rotation.

10. Device according to Claim 6, characterised in that the sliding blocks of the lower double hinge are made of anti-friction material.

11. Sea Led door which is hinged with the frame of a safe, strong-room or similar object by means of the hinging device according to the preceding claims and which can be locked in position in the opening of the frame by means of a system of latches which can be -operated by a central hand-wheel, characterised in that each Latch consists of a plate which is guided in a block fixed to the door, so as to perform movements in a plane parallel to the external surface of the door, in that the said plate is extended at its free end by means of an end-piece inclined towards the door reLative to the plane of movement, the said end-piece having two opposite working faces designed to cooperate with the opposite surfaces of an element fixed to the frame, and in that the face of the said end-piece facing the door has a depressed part, as a result of which this face is separated from the associated surface of the element fixed to the frame when the latch is in the fully engaged position in the direction of the frame.

12. Door according to CLaim 11, characterised in that the said element fixed to the frame consists of a block with an internal cavity which has the said opposite surfaces designed to cooperate with the opposite working faces of the end-piece of the said plate, the said surfaces-being inclined at the same angle as the corresponding faces of the - said end-piece, and the surface cooperating with the face provided with the depressed part being provided with a corresponding projecting part, the distance between the said opposite surfaces of the cavity inside the block fixed to the frame being greater than the distance between the opposite working faces of the end-piece, as a result of which, when the end-piece is completely inside the said cavity, its outer working face is in contact with the associated surface of the cavity, whereas its opposite face with the depressed part is Located at a distance from the associated surface of the cavity and of its projecting part.

13. Door according to Claim 11, characterised in that the element fixed to the frame comprises two rollers which are located opposite each other and constitute the surfaces intended to cooperate with the opposite working faces of the end-piece of the said plate.

Drawing