UNIT FOR THE INSPECTION/MAINTENANCE OF THE UNDER-BRIDGE ZONE OF A BRIDGE OR VIADUCT

Abstract

 There is described a unit (1) for the inspection/maintenance of the under-bridge zone (2) of a bridge (3), the unit (1) comprising: a base (4) configured to be arranged on the road surface (5) of the bridge (3) to be inspected; and an articulated structure (7) movably coupled to the base (4) at its initial end (7a) and configured to carry an inspection device (8) at its free end (7b) opposite to the initial end (7a); the articulated structure (7) is movable between a compact configuration at the base (4) to allow transport of the unit (1), and an extended configuration extending from the base (4) to allow the inspection operation; the articulated structure (7) is divided into a plurality of sections (A, B, C, D) articulated relative to one another, at least some of which comprise at least one pair of profiled beams (11), wherein the profiled beams (11) of each pair are slidable onto one another between a closed position and an open position to allow the movement of the articulated structure (7) between the compact configuration and the extended configuration.

Description

CROSS REFERENCE TO ELATED APPLICATIONS

[0001] This patent application claims priority from Italian patent application No. 102021000026105 filed on October 12, 2021.

TECHNICAL FIELD

[0002] The present invention relates to a unit for the inspection and/or the maintenance of the under-bridge zone of a bridge or viaduct or overpass, in particular of the lower portion of the deck of a bridge or viaduct or overpass.

BACKGROUND ART

[0003] Units are known for the inspection/maintenance of the under-bridge zone of bridges or viaducts or overpasses, these units generally comprising:

• a base, fixable on a suitable transport system, such as a truck, usually rotatable about a vertical axis; and
• an articulated structure movably fixed to the base and which can typically be articulated between a configuration in which it is compact, closed on itself at the base for transport, and an extended configuration in which it is extended to reach the zone to be inspected.

[0004] Usually, the inspection units of the type described above also comprise a basket fixed at the free end of the articulated structure which is configured to accommodate one or more operators for performing visual inspection of the under-bridge zone or carrying out maintenance operations/work in this zone.

[0005] The articulated structure is generally defined by a "crane" type structure and typically comprises a plurality of beams or struts divided into sections articulated relative to one another to allow movement and to reach the zone to be inspected starting from the point of the road surface (i.e., of the carriageway) on which the base is placed.

[0006] In more detail, a typical articulated structure comprises a first section coupled to the base, a second section coupled to the first section and configured for moving the basket horizontally away from the road surface, a third section coupled to the second section and configured for lowering the basket vertically below the level of the road surface, and a fourth section coupled to the third section, carrying the basket at its free end and configured for bringing said basket horizontally closer to the road surface, i.e., to the deck of the bridge, to reach the under-bridge zone.

[0007] The beams or struts can be lattice structures or defined by box-like elements made of strong sheet metal.

[0008] An example of inspection unit of the type described above is illustrated in US-A-4696371.

[0009] In order to produce increasingly compact units, the use of telescopic structures is known in the field.

[0010] These telescopic structures comprise, for each section, at least one pair of tubular elements inserted one inside the other and in this way slidable onto one another to determine the extension of the related section.

[0011] The Applicant has observed that the inspection units of the aforesaid type are susceptible to further improvements.

[0012] In fact, the presence of telescopic elements in the articulated structure makes the use of oversized hydraulic actuators, which are costly and cumbersome, necessary.

[0013] Moreover, with the increase in the telescopic elements present in each section, the size of the outermost tubular element, which must support the weight of all the internal elements in extended configuration, will necessarily increase, leading to an increase in the overall dimensions and in the total weight of each section, which translates into a further oversizing of the aforesaid actuators.

[0014] Additionally, with the increase in the weight and in the overall dimensions of the articulated structure an adequate base and, above all, heavy goods vehicles configured for transporting the structure will be necessary, thus resulting in a further increase in the total costs.

[0015] Finally, the Applicant has observed how prior art inspection units are somewhat inflexible from the point of view of adaptability to different operating conditions. In fact, there are bridges with decks of various depths, with narrower or wider carriageways, and so forth. When these conditions vary, different inspection units are necessary to satisfy these varying conditions.

SUBJECT MATTER AND SUMMARY OF THE INVENTION

[0016] The object of the present invention is to provide a unit for the inspection of the under-bridge zone of a bridge or viaduct which is highly reliable and has a limited cost, and allows at least some of the drawbacks specified above and related to prior art inspection systems to be overcome.

[0017] According to the invention, this object is achieved by a unit for the inspection of an under-bridge zone as claimed in claim 1.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] For a better understanding of the present invention, a preferred, but non-limiting, embodiment thereof is described below purely by way of example and with the aid of the accompanying drawings, wherein

• Fig. 1 is a side view, partially sectional and with parts removed for clarity, of an inspection unit produced according to the present invention in an extended configuration;
• Fig. 2 is a side view, in enlarged scale and with parts removed for clarity, of the inspection unit of Fig. 1 in a compact configuration;
• Fig. 3 is a perspective view, in enlarged scale and with parts removed for clarity, of part of the inspection unit of Fig. 1;
• Fig. 4 is a perspective view, in enlarged scale and with parts removed for clarity, of another part of the inspection unit of Fig. 1;
• Fig. 5 is a side view, in enlarged scale and with parts removed for clarity of a detail of the part of the unit shown in Fig. 4; and
• Fig. 6 is a perspective view, in enlarged scale and with parts removed for clarity, of a further part of the inspection unit of Fig. 1.

DETAILED DESCRIPTION

[0019] With reference to Figs. 1 and 2, a unit for the inspection/maintenance of the under-bridge zone 2 of a bridge or viaduct or overpass or walkway 3 is indicated as a whole with 1.

[0020] It is specified that in the present description although specific reference will be made to a bridge 3, this term is also to be considered equally interchangeable with viaduct, overpass, walkway or the like.

[0021] It is also specified that the term "under-bridge zone" is meant as the lower exposed portion of the deck of a bridge.

[0022] The inspection unit 1 comprises, essentially:

• a base 4 configured to be arranged on the road surface 5 of the bridge 3 to be inspected, in particular configured to be arranged in a fixed position corresponding to a precise point of the road surface 5 of the bridge 3 to be inspected; and
• an articulated structure 7 movably coupled to the base 4 (according to a method described below) at its initial end 7a and configured to carry, in particular bringing into use, an inspection and/or maintenance device 8 at its free end 7b operatively opposite to the initial end 7a.

[0023] According to the preferred embodiment, the device 8 is defined by a video camera or camera or any other optical sensor capable of acquiring static or dynamic images in the visible or infrared range or other wavelengths appropriate for a structural inspection.

[0024] Alternatively, the device 8 is defined by 3D-scanning device, for example a digital point cloud scanner or a LiDAR scanner.

[0025] Alternatively, the device 8 is defined by a robotic arm articulated on the free end 7b of the articulated structure 7 and configured to automatically carry out maintenance/inspection operations.

[0026] Preferably, as illustrated in Fig 1, the device 8 includes a video camera or camera or any other optical sensor and the robotic arm.

[0027] According to a first embodiment, the base 4 can rest directly on the road surface 5 of the bridge 3 to be inspected, the road surface 5 thus defining a support surface for the base 4 itself.

[0028] Alternatively, the base 4 can be fixed on a transport system (not illustrated), for example a van, a truck or a vehicle on rails. In this case, the support surface is defined by the platform of the transport system on which the base 4 is fixed.

[0029] Conveniently, the base 4 is rotatably arranged on the support surface, whether this is the road surface 5 or the platform of the transport system.

[0030] In particular, the base 4 is rotatable about a rotation axis orthogonal to the support surface.

[0031] In this regard, the base 4 advantageously comprises a plurality of wheels 10 to allow a rotation of the base 4 itself with respect to the support surface, for example with respect to the road surface 5 or with respect to the transport system carrying the base 4 itself.

[0032] This solution allows a stable rotation of the base 4 about the rotation axis to be obtained.

[0033] The articulated structure 7 is movable between:

• a compact configuration (closed on itself) at the base 4 (Fig. 2), or closed configuration, to allow transport of the unit 1; and
• an extended configuration extending from the base 4 (Fig. 1), or open configuration, to allow the inspection and/or maintenance operation.

[0034] In this regard, the articulated structure 7 is divided into, i.e., comprises, a plurality of sections articulated relative to one another.

[0035] In more detail, the articulated structure 7 comprises:

• a first section A coupled to the base 4 in an articulated manner, in particular hinged, to allow the free end 7b, i.e., the device 8, to move away from the road surface 5, in particular an upward movement;
• a second section B coupled to the first section A in an articulated manner, in particular hinged, cantilevered therefrom and configured for moving the free end 7b, i.e., the device, away from the road surface 5, in particular in a horizontal direction;

• a third section C coupled to the second section B in an articulated manner, in particular hinged, cantilevered therefrom and configured for lowering the free end 7b, i.e., the device, below the road surface 5 along a direction transversal to the road surface 5, in particular along a direction perpendicular to the road surface 5, more in particular along a vertical direction parallel to the direction of gravity; and
• a fourth section D coupled to the third section C in an articulated manner, in particular hinged, cantilevered therefrom and configured for bringing the free end 7b, i.e., the device 8, closer to the road surface 5 in order to reach the under-bridge zone 2 to be inspected, in particular to bring it closer along a horizontal direction.

[0036] According to an alternative embodiment, not illustrated, the articulated structure 7 only includes three sections, for example: the first section A arranged inclined and sufficiently long to allow the side barrier of the bridge 3 to be passed over in horizontal direction; the third section C hinged directly to the first section A; and the fourth section D.

[0037] In practice, in this case, the articulated structure 7 does not include the second section B, thereby simplifying the architecture of the unit 1.

[0038] However, the presence of the second section B is particularly advantageous as it allows the size of the first section A to be reduced.

[0039] Preferably, in the case in which the device 8 is defined by a robotic arm, the articulated structure 7 comprises a further section E which is defined by this robotic arm and is articulated, in particular hinged, to the fourth section D, more in particular cantilevered therefrom.

[0040] According to an important aspect of the present invention, at least some of the sections A, B, C, D comprise at least one pair of profiled beams 11 slidable onto one another, i.e., externally to one another, between a closed position and an open position to allow the movement of the articulated structure 7 between the compact configuration and the extended configuration.

[0041] In particular, each profiled beam 11 has a central longitudinal axis (not illustrated) and extends longitudinally along this axis.

[0042] More in particular, each profiled beam 11 is defined by an elongated box element, preferably having a rectangular section.

[0043] Alternatively, each profiled beam 11 is defined by an extrusion, solid or hollow with internal lattice structure.

[0044] In other words, each profiled beam 11 is defined by a longitudinal beam element, preferably having a rectangular section.

[0045] According to the invention, the profiled beams 11 of each section A, B, C, D are slidable onto one another at their respective external longitudinal surfaces 11a, 11b.

[0046] In detail, for each pair of profiled beams 11 slidable onto one another, a first profiled beam 11 has a first external surface 11a and a second profiled beam 11 has a second external surface 11b, the first external surface 11a being slidingly coupled to the second external surface 11b.

[0047] In more detail, the first external surface 11a carries a first slide-guide element 12, for example a sliding block or a longitudinal groove defining a slide, and the second external surface 11b carries a second slide-guide element 13, for example one or more longitudinal protrusions or ribs defining a guide or rail, complementary in sliding to the first slide-guide element 12.

[0048] As a result of this solution, it is possible to obtain a linear and controlled movement of the profiled beams 11 between the open position and the closed position.

[0049] Advantageously, at least the third section C and the fourth section D comprise at least one respective pair of profiled beams 11 slidable (externally) onto one another.

[0050] Conveniently, also the first section A comprises at least one respective pair of profiled beams 11 slidable (externally) onto one another.

[0051] Preferably, also the second section B comprises at least one respective pair of profiled beams 11 slidable (externally) onto one another.

[0052] According to this preferred and non-limiting embodiment, all the sections A, B, C and D of the articulated structure comprise at least one pair of profiled beams 11 according to the invention.

[0053] In particular, as can be seen in Fig. 1, which illustrates the whole articulated structure 7 in the extended configuration:

• the first section A comprises three profiled beams 11, a first of which is hinged to the base 4, a second of which is slidable onto the first and a third of which is slidable onto the second;
• the second section B comprises a pair of profiled beams 11, a first of which is hinged to the third of the profiled beams 11 of the first section and a second of which is slidable onto the first;

• the third section C comprises four profiled beams 11, a first of which is hinged to the second of the profiled beams 11 of the second section B, a second of which is slidable onto the first, and so forth up to the fourth profiled beam 11; and
• the fourth section D comprises five profiled beams 11, a first of which is hinged to the fourth of the profiled beams 11 of the third section C, a second of which is slidable onto the first and so forth up to the fifth profiled beam 11, which defines the free end 7b and carries, at this free end 7b, the device 8.

[0054] It is clear how each section A, B, C, D can comprise any number of profiled beams 11, based on the inspection needs and on the type of bridge 3 to be inspected. In this regard, the articulated structure 7 is of modular type.

[0055] As specified above, each section A, B, C, D is articulated relative to the others.

[0056] In order to control the pivoted movement of the sections relative to one another, the unit 1 comprises:

• a first actuator 14 operatively interposed between the first section A and the second section B to control an articulated motion therebetween; and
• a second actuator 15 operatively interposed between the second section B and the third section C to control an articulated motion therebetween; and
• a third actuator 16 operatively interposed between the third section C and the fourth section D to control an articulated motion therebetween.

[0057] Advantageously, the unit 1 further comprises a fourth actuator 17 operatively interposed between the base 4 and the first section A to control an articulated motion of the first section A with respect to the base 4.

[0058] Advantageously, the first actuator 14, the second actuator 15 and the third actuator 16 are of the pneumatic type and include a cylinder fixed to one of the sections to be coupled and a rod slidable in the cylinder and fixed to the other of the sections to be coupled.

[0059] Advantageously, also the fourth actuator 17 is of the pneumatic type.

[0060] In practice, the actuators 14, 15, 16, 17 are configured for controlling the relative pivoted rotation between the sections A, B, C, D and, in the case of the fourth actuator 17, the pivoted rotation of the first section A with respect to the base.

[0061] The use of pneumatic actuators 14, 15, 16, 17 is made possible by the fact that the profiled beams 11 are slidable externally onto one another and are not of the telescopic type. This makes the articulated structure 17 sufficiently light to avoid the use of more costly and cumbersome hydraulic cylinders.

[0062] More precisely, the presence of telescopic elements makes it necessary to use actuators between the sections of the articulated structure having an arm of lower strength, due to the construction and geometric constraints of the telescopic elements. This results in the use of oversized hydraulic actuators.

[0063] The Applicant has observed that through the implementation of profiled beams 11 slidable externally onto one another it is possible to implement actuators having arms with higher strengths and, consequently, a lower cost and a smaller size. This also allows pneumatic actuators to be used.

[0064] Alternatively, one or more of the actuators 14, 15, 16, 17 could be of hydraulic or electric type, for example could comprise a linear motor.

[0065] For the sake of brevity, reference will be made hereinafter to a single pair of profiled beams 11 slidable externally onto one another.

[0066] Nonetheless, the structural and functional features described in correlation with the profiled beams 11 are also applicable to each pair of profiled beams 11 slidable onto on another in a given section A, B, C, D of the articulated structure 7.

[0067] Advantageously, the unit 1 comprises an actuator 18, 19 operatively coupled to the pair of profiled beams 11 to control the relative sliding of the profiled beams 11 between the closed position and the open position.

[0068] In the example described the type of this actuator 18, 19 depends on the section A, B, C, D in which the pair of profiled beams 11 is present.

[0069] In a first case, the actuator comprises a pneumatic actuator 18 and includes a cylinder 18a carried by one of the profiled beams 11 of the pair and a rod 18b slidable in the cylinder and fixed to the other of the profiled beams 11 of the pair.

[0070] According to the non-limiting example described and illustrated here, this pneumatic actuator 18 is present, for example, to control the relative sliding of the profiled beams of the sections A, B and D, as can be seen in Figs. 3 and 6. Advantageously, these sections comprise the same number of pneumatic actuators 18 as the pairs of profiled beams 11 slidable onto one another (as shown in Fig. 6 for the fourth section D).

[0071] In a second case, the actuator is defined by a rope-winch system 19 comprising a winch 19a fixed to one of the profiled beams 11 of the pair and a rope 19b windable on the winch 19a and operatively coupled to the other of the profiled beams 11 of the pair.

[0072] According to the non-limiting example described and illustrated here, only the third section C comprises the rope-winch system 19.

[0073] In particular, each profiled beam 11 of the third section C has at least one pulley 20 for the operative coupling with the rope 19b, and only one winch 19a is present, carried by the first of the profiled beams 11 of the section C.

[0074] In use, the rope 19b is unwindable off the winch 19a to determine a gravity-caused displacement of the profiled beams 11 from the closed position to the open position, and is windable on the winch 19a to determine the displacement of the profiled beams 11 from the open position to the closed position.

[0075] This configuration is advantageously implementable in the articulated structure 7 due to the presence of the profiled beams 11 according to the present invention. In fact, as the profiled beams 11 are slidable externally onto one another, they allow a simpler implementation of the rope-winch system 19, with respect to the case of telescopic elements, which require an internal rope-element coupling.

[0076] The rope-winch system 19 allows the movement of the profiled beams 11 in a simple and economical manner.

[0077] The rope-winch system 19 is particularly advantageous when implemented in the third section C, as it allows the force of gravity to be exploited for the extension of the third section C itself.

[0078] Advantageously, the winch 19a is provided with a braking and blocking system to selectively control the unwinding of the rope 19b.

[0079] Alternatively, one or more of the sections A, B and D can comprise the rope-winch system 19 in place of the pneumatic actuators 18.

[0080] Alternatively, one or more sections A, B, C and D comprise one or more pneumatic actuators 18 between some pairs of profiled beams 11 and the rope-winch system 19 between the remaining pairs of the same section.

[0081] By examining the features of the inspection unit 1 produced according to the present invention the advantages that can be obtained therewith are clear.

[0082] In particular, due to the configuration described above, it is possible to reduce the overall dimensions of the articulated structure 7 and consequently of the unit 1.

[0083] In fact, the presence of the profiled beams 11 slidable externally onto one another makes it possible to avoid the use of telescopic elements, which are undoubtedly more difficult to manage: for example, with the increase in the telescopic elements present in each section, the size of the outermost tubular element will necessary increase, leading to an increase in the overall dimensions and in the total weight of each section, which translates into a further oversizing of the actuators necessary for their movement. This is avoided due to the fact that the profiled beams 11 according to the invention are slidable externally onto one another.

[0084] Moreover, the profiled beams 11 increase the compactness of the articulated structure 7, and consequently of the unit 1, in compact configuration, relative to the use of telescopic elements (see Fig. 2).

[0085] In addition, due to the lighter weight and greater compactness, the configuration described above allows the use of a lighter base 4 and, above all, a conventional transport system and not a heavy goods vehicle. In fact, the unit 1 according to the invention can be loaded onto a vehicle of less than 3.5 tonnes.

[0086] Moreover, the particular configuration of the profiled beams 11 means that the articulated structure 7 is of modular type, where each module is defined by a single profiled beam 11. This is not possible in the case of telescopic elements, as tubular elements cannot be eliminated or added according to needs. Instead, this is possible in the case of the unit 1 according to the present invention: in fact, it is sufficient to decouple or couple the slide-guide elements 12, 13 and the respective actuators 14, 15, 16 to modify the number of the profiled beams 11 of each section A, B, C, D, thereby making the articulated structure 7 flexible and adaptable to the different inspection needs.

[0087] In other words, modularity is guaranteed, unlike the case of telescopic elements, which are not normally modular.

[0088] Moreover, as already specified above, the presence of profiled beams 11 slidable externally onto one another allows the implementation of actuators 14, 15, 16 between the sections A, B, C, D having arms with higher strengths with respect to the case of telescopic elements, which allows the cost and size of these actuators to be reduced.

[0089] Additionally, the lightness, compactness and modularity of the unit 1 allow the safety of the inspection and/or maintenance operation to be increased in general as, according to the severity of the damage estimated and according to how unsafe the bridge 3 to be inspected is, it is possible to adapt the unit 1, also using a light transport system.

[0090] In this regard, the unit 1 is preferably loadable on an autonomously driven means of transport, so that no operators are required to drive the transport system, thereby reducing the risk of collapses and injuries.

[0091] Moreover, due to the presence of the profiled beams 11 it is possible to provide each pair of profiled beams 11 slidable onto one another with a dedicated actuator 18, unlike the case of telescopic elements, which require a single actuator. This allows the stroke of these actuators to be reduced, with benefits from the point of view of stability.

[0092] Finally, the innovative configuration of the unit 1 allows the arrangement and the management of the cable carrier elements or "cable drag chains" along the sections A, B, C, D to be improved with respect to the case in which telescopic elements are used. In fact, it is sufficient to arrange the "cable drag chains" on the free external surfaces of the profiled beams 11, i.e., the external surfaces that are not slidingly coupled to one another. This gives rise to an undeniable architectural simplification with respect to the case in which telescopic elements are used. In fact, in this case the cable drag chains must necessarily remain on the outside when the telescopic elements are in compact configuration, thereby determining a greater overall dimension of the unit.

[0093] It is clear that modifications and variants can be made to the inspection unit 1 described and illustrated here without departing from the scope of protection defined by the claims.

[0094] In particular, the free end 7b could carry a tool for the cleaning or maintenance of the under-bridge zone 2, for example a tool for checking the tightening of bolts or a member for depositing detergents or anti-corrosion paints.

[0095] More in particular, the device 8 could be defined by:

• a video camera or camera or any other optical sensor capable of acquiring static or dynamic images in the visible or infrared range or other wavelengths appropriate for a structural inspection; and/or
• a 3D-scanning device, for example a digital point cloud scanner or a LiDAR scanner; and/or
• a tool for the cleaning or maintenance of the under-bridge zone (2), for example a tool for checking the tightening of bolts or a member for depositing detergents or anti-corrosion paints; and/or
• a robotic arm articulated on said free end (7b), carrying on its head a tool for the cleaning or maintenance of the under-bridge zone (2) and/or a video camera or camera or any other optical sensor, and controllable to move the tool and carry out maintenance and/or cleaning and/or inspection operations.

Claims

1. Unit (1) for the inspection/maintenance of the under-bridge zone (2) of a bridge (3), the unit (1) comprising:

- a base (4) configured to be arranged on the road surface (5) of the bridge (3) to be inspected; and

- an articulated structure (7) movably coupled to the base (4) at its initial end (7a) and configured to carry an inspection/maintenance device (8) at its free end (7b) opposite to the initial end (7a);

the articulated structure (7) being movable between a compact configuration at the base (4) to allow transport of the unit (1), and an extended configuration extending from the base (4) to allow the inspection/maintenance operation;

the articulated structure (7) being divided into a plurality of sections (A, B, C, D) articulated relative to one another, at least some of which comprise at least one pair of profiled beams (11), wherein each profiled beam (11) has a longitudinal axis and extends longitudinally along this longitudinal axis; wherein the articulated structure (7) comprises:

- a first section (A, B) coupled to the base (4) in an articulated manner to allow said free end (7b) to move away from the road surface (5);

- a second section (C) coupled to the first section (A, B) in an articulated manner and configured for lowering said free end (7b) below the road surface (5) along a direction transversal to the road surface (5); and

- a third section (D) coupled to the second section (C) in an articulated manner, carrying said free end (7b) and configured for bringing the free end (7b) closer to the road surface in order to reach the under-bridge zone (2) to be inspected/maintained;

wherein the profiled beams (11) of each pair are slidable onto one another at respective external longitudinal surfaces (11a, 11b) thereof between a closed position and an open position to allow the movement of the articulated structure (7) between the compact configuration and the extended configuration;

and wherein at least the second section (C) and the third section (D) comprise at least a respective said pair of profiled beams (1) slidable onto one another.

2. Unit as claimed in claim 1, wherein a first profiled beam (11) of said pair of profiled beams has a first external surface (11a), and a second profiled beam (11) of said pair of profiled beams has a second external surface (11b), the first external surface (11a) being slidingly coupled to the second external surface (11b);
and wherein the first external surface (11a) carries a first slide-guide element (12) and the second external surface (11b) carries a second slide-guide element (13) complementary in sliding to said first element (12).

3. Unit as claimed in claim 1 or 2, wherein also the first section (A, B) includes at least one respective said pair of profiled beams (11) slidable onto one other.

4. Unit as claimed in any one of the preceding claims, and comprising an actuator (18) operatively coupled to the pair of profiled beams (11) to control the relative sliding of the profiled beams (11) between the closed position and the open position;
wherein said actuator (18) is of the pneumatic type and includes a cylinder (18a) carried by one of the profiled beams (11) of the pair and a rod (18b) slidable in the cylinder and fixed to the other of the profiled beams of the pair.

5. Unit as claimed in any one of claims 1 to 3, and comprising an actuator (19) operatively coupled to the pair of profiled beams (11) to control the relative sliding of the profiled beams (11) between the closed position and the open position;
wherein said actuator is defined by a rope-winch system (19) comprising a winch (19a) fixed to one of the profiled beams (11) of the pair and a rope (19b) windable on the winch (19a) and operatively coupled to the other of the profiled beams (11) of the pair.

6. Unit as claimed in claim 5, wherein at least said second section (C) comprises said rope-winch system (19),

wherein each profiled beam (11) of the second section (C) has at least one pulley (20) for the operative coupling with the rope (19b),

wherein the rope (19b) is unwindable off the winch (19a) to determine a gravity-caused displacement of the pair of profiled beams (11) from the closed position to the open position,

and wherein the rope (19b) is windable on the winch (19a) to determine the displacement of the pair of profiled beams (11) from the open position to the closed position.

7. Unit as claimed in claim 1 or 3, and comprising:

- a first actuator (14, 15) operatively interposed between the first section (A, B) and the second section (C) to control an articulated motion therebetween;

- a second actuator (16) operatively interposed between the second section (C) and the third section (D) to control an articulated motion therebetween;

wherein the first actuator (14, 15) and the second actuator (16) are of the pneumatic type and include a cylinder fixed to one of the sections to be coupled and a rod slidable in the cylinder and fixed to the other of the sections to be coupled.

8. Unit as claimed in any one of the preceding claims, wherein the base (4) comprises a plurality of wheels (10) to allow a rotation of the base (4) itself with respect to a support surface or with respect to the road surface (5).

9. Unit as claimed in any one of the preceding claims, wherein the inspection/maintenance device (8) comprises:

- a video camera or camera or any other optical sensor capable of acquiring static or dynamic images in the visible or infrared range or other wavelengths appropriate for a structural inspection; and/or

- a 3D-scanning device, for example a digital point cloud scanner or a LiDAR scanner; and/or

- a tool for the cleaning or maintenance of the under-bridge zone (2), for example a tool for checking the tightening of bolts or a member for depositing detergents or anti-corrosion paints; and/or

- a robotic arm articulated on said free end (7b), carrying on its head a tool for the cleaning or maintenance of the under-bridge zone (2) and/or a video camera or camera or any other optical sensor, and controllable to move the tool and carry out maintenance and/or cleaning and/or inspection operations.

Drawing