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(11) | EP 3 216 741 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | CRANE COMPRISING AN EXTENDING BOOM AND A DEVICE FOR MEASURING THE EXTENSION OF SAID EXTENDING BOOM |
| (57) There is proposed a crane (1) comprising: - an extending boom (6) comprising at least one pair of boom sections (9', 9"), wherein said at least one pair of boom sections comprises: - a first boom section (9') and a second boom section (9") translatingly movable with respect to the first boom section (9') between an extended position and a retracted position, wherein said first (9') and second boom sections (9") have each a proximal end (19) and a distal end (20); - a flexible conduit (17) integrally translatingly connected to the distal end (20') of the first boom section (9') and to the proximal end (19") of the second boom section (9"), so that during the passages from the extended and retracted positions of the second boom section (9"), the portion of the flexible conduit (17) comprised between the distal end (20') of the first boom section (9') and the proximal end (19") of the second boom section (9") gradually flips over; - a device (23) for measuring the extension of the extending boom (6), whereby said device (23) for measuring the extension of the extending boom (6) comprises at least one flexible portion (24) integral with the flexible conduit (17) of the at least one pair of boom sections (9', 9"), and at least one sensor (25) adapted to detect the flipping-over of said at least one flexible portion (24). |
Technical field of the invention
[0001] The present invention refers to a crane, particularly to a loading crane, provided with an extending boom and a device for measuring the extension of such extending boom.
Prior art
[0002] Modern cranes generally feature a plurality of degrees of freedom, among them the movements executable by the extending boom thereof. Generally, the extending boom comprises a plurality of coaxial boom sections, sliding with respect to each other. As the boom sections gradually project, the axial extension of the extending boom increases, which must be monitored for a correct and safe operation of the crane. Actually, as the axial extension of the extending boom increases, the risk of flipping over the crane increases both for the same hoisted load and for the same hoisting torque, for example. Moreover, as a function of the extension of the extending boom, it could be necessary to limit the performance of the crane due to safety reasons.
[0003] For this reason, the cranes can be provided with dedicated sensors measuring the axial extension of the projecting boom sections.
[0004] The types of sensors commonly used for measuring the axial extension of the extending boom are different.
[0005] A type of used sensor measures, by angular encoders, the unwound length of a metal wire connected to the last boom section of the extending boom. The greater the extension of the boom, the greater the unwound length of such wire measured by the encoder will be. However, such known solution has the following disadvantages:
- wear of the components, so that it is required a frequent maintenance;
- great dimensions when the wire is completely wound;
- the measurement of the extension can be affected when the extending boom is bent by a heavy load;
- the system is not capable of distinguishing the sequence by which the individual boom sections project, but it can only determine the overall extension.
[0006] Therefore, systems alternative to the conventional wire systems have been proposed. For example, systems which associate electric resistances to the individual boom sections and which measure the potential difference caused by the projection of each boom section have been proposed. Other known systems comprise measuring the relative positions among the boom sections by means of electric contacts, laser measurers, GPS probes, electromagnetic waves, or by radio waves.
[0007] However, these systems, although overcome some disadvantages caused by the conventional measurement by unwinding a wire, are technologically complicated and expensive.
Summary of the invention
[0008] Therefore, an object of the present invention consists of providing a crane equipped with a device for measuring the extension of the extending boom, which is sufficiently simple, compact, requiring a limited maintenance, which is sufficiently cost effective, and enables to determine the sequence by which the boom sections of the extending boom project, and which is not substantially affected by a possible bending of the extending boom.
Brief description of the drawings
[0011] For better understanding the invention and the advantages thereof, some exemplifying non-limiting embodiments thereof will be described herein below by referring to the attached drawings, wherein:
Figure 1 is a side view of a crane according to a possible embodiment of the invention;
Figure 2 is a schematic illustration of an extending boom of a crane according to the invention in different configurations;
Figures 3a and 3b are perspective views of a portion of an extending boom of a crane according to the invention in two different configurations;
Figure 4 is a schematic view of an extending boom of a crane according to the invention provided with a device for measuring the extension of the extending boom itself;
Figure 5 is a perspective schematic illustration of a device for measuring the extension of the extending boom of a crane according to a possible embodiment of the invention;
Figure 6 is a perspective schematic view of a portion of a device for measuring the extension of the extending boom of a crane according to a possible embodiment of the invention;
Figure 7 is a schematic illustration of an extending boom of a crane according to a possible embodiment of the invention;
Figure 8 is a schematic illustration of an extending boom of a crane according to a possible embodiment of the invention.
Detailed description of the invention
[0012] With reference to the accompanying Figure 1, a crane, particularly a hydraulic loading crane (commonly known as "loader crane") according to a possible embodiment, is generally indicated by reference 1.
[0013] The crane 1, according to the illustrated embodiment, comprises a column 2 rotating about an axis A1, a first boom 3 connected to the column 2 and ascendingly and descendingly rotating, with respect to the column 2, about an axis A2 normal to the axis A1. A first operating cylinder 4, preferably a hydraulic one, by a first articulated system 5, moves the first boom 3 with respect to the column 2. Moreover, the crane 1 comprises a second boom 6 connected to the first boom 3 and ascendingly or descendingly rotating with respect to the first boom 3 about an axis A3 parallel to the axis A2. A second operating cylinder 7, preferably a hydraulic one, by a second articulated system 8, moves the second boom 6 with respect to the first boom 4.
[0014] The second boom 6 is configured for being extendable and to this purpose comprises a plurality of boom sections 9 translatingly movable with respect to each other, in order to be capable of modifying the axial extension of the second boom 6 itself. The boom sections 9 are moved by corresponding further, preferably hydraulic, operating cylinders 10. Further details about the extending boom 6 will be given in the following.
[0015] To the second boom 6, particularly to the end of its last boom section, that is the one which can reach the greatest axial extension, is associated a third boom 11, which acts as an extension of the crane. The third boom 11 is connected to the second boom 6 and is ascendingly or descendingly rotating with respect to it about an axis A4 parallel to the axis A3. A third operating cylinder 12, preferably a hydraulic one, by a third articulated system 13, moves the third boom 11 with respect to the second boom 6. Preferably, also the third boom 11 is extendable, and to this purpose comprises a plurality of boom sections 14 translatingly movable with respect to each other in order to be capable of modifying the axial extension of the third boom 11 itself. The boom sections 14 of the third boom 11 are moved by corresponding further, preferably hydraulic, operating cylinders 15. Operating devices of different type, for example a winch, not shown in Figure 1, can be provided at an end 16 of the third boom 11.
[0016] The second boom 6 comprises one or more flexible conduits 17 associated to the boom sections 9, adapted to receive inside for example hydraulic tubes and/or electric cables of the crane, particularly for actuating the third boom 11 and/or operating devices associated thereto. Moreover, as it will be described particularly in the following, a device for measuring the extension of the boom sections 9 of the extending boom is associated to the flexible conduits 17.
[0017] Referring now to Figures 3a and 3b, they are partial illustrations of three boom section 9', 9" and 9"' of the second boom 6. Of course, the number of the boom sections can be different from three. It is observed that the first boom section 9' can be movable with respect to other not illustrated boom sections, or, as an alternative, can be translatingly fixed with respect to the second boom 6 as a whole. The three boom sections 9', 9" and 9"' form two subsequent pairs of boom sections. Particularly, a first pair of boom sections 18' comprises the first 9' and second boom sections, while a second pair of boom sections 18" comprises the second 9" and third 9"' boom sections. A boom section of each pair of boom sections is translatingly movable with respect to the previous boom section. Particularly, with reference to Figures 3a and 3b, the second boom section 9" is translatingly movable with respect to the first boom section, while the third boom section 9"' is translatingly movable with respect to the second boom section 9". A boom section of each pair of boom sections is movable with respect to the previous boom section between a retracted position and an extended one. For example, with reference to the second pair of boom sections 18", in Figure 3a the third boom section 9"' is in a position completely retracted with respect to the second boom section 9", while in Figure 3b the third boom section 9"' is translated with respect to the second boom section 9", so to take a partially extended configuration. Compared to the configuration in Figure 3b, the third boom section 9"' can further translate towards the outside (to the right in the figure) with respect to the second boom section 9", until it reaches a completely extended position (not illustrated). Of course, the second boom section 9" can analogously translate between a retracted position and an extended position with respect to the first boom section 9'.
[0018] Each pair of boom sections comprises one of the above cited flexible conduits 17, connecting a distal end 20 of the first boom section of the pair of boom sections to a proximal end 19 of the second boom section of the pair. In the present description and in the accompanying claims, it is noted that the term "proximal end" must be understood as an end proximate (not necessarily the most proximate) to the origin of the boom sections, defined by the axis A3 for example, while the term "distal end" must be understood as the end at the greater distance (not necessarily at the greatest distance) from such origin of the boom sections from the proximal end.
[0019] Particularly, with reference to the example in Figures 3a and 3b, the first pair of boom sections 18' comprises a first flexible conduit 17' connected to the distal end 20' of the first boom section 9' and to the proximal end 19" of the second boom section 17". Similarly, the second pair of boom sections 18" comprises a second flexible conduit 17" connected to the distal end 20" of the second boom section 9" and to the proximal end 19"' of the third boom section 9"'. It is to be observed that the flexible conduits, at the connecting points to the boom sections, are translatingly integral with the boom sections themselves, while in the intermediate lengths between the connecting points to the boom sections, the flexible conduits are disengaged from the boom sections themselves, and therefore are free of taking a spatial orientation different from these.
[0020] Preferably, the flexible conduits 17 comprise chains, whose links define an inner space where the above cited tubes and electrical cables (in addition to the device for measuring the extension of the boom sections, as it will be explained in the following) can be received. Preferably, each boom section comprises a channel 21 where the flexible conduit 17 can be received when the second boom section of the pair is in the retracted position. With reference to Figure 3a, the first conduit 17' is received in the channel 21' of the first boom section 9', while the second conduit 17" is received in the channel 21" of the second boom section 9". In the example in Figure 3a, it is illustratively assumed that the third boom section 9"' is the last boom section of the second boom 6 and therefore is devoid of a third conduit. The cables and tubes at the third boom section can be fixed to the third channel 21"' between the distal 19"' and proximal ends 20"' thereof. Moreover, it is to be observed that in the embodiment of Figures 3a and 3b, the proximal and distal ends are conventionally referred to the channels.
[0021] Since the channels of subsequent boom sections are preferably overlapped on each other, in each pair of boom sections the flexible conduit preferably forms a curvilinear length 22 in proximity of the proximal end 19 of the boom section to which the flexible conduit 17 itself is connected. Therefore, for example, the first flexible conduit 17' forms a curvilinear length 22' in proximity of the proximal end 19" of the second boom section 9", and the second flexible conduit 17" forms a curvilinear length 22" in proximity of the proximal end 19"' of the third boom section 9"'.
[0022] Referring, for example, to the second conduit 17" itself, when the third boom section 9"' is in the retracted position (Figure 3a), the second conduit 17" is completely received in the second channel 21", with the exception of the curvilinear length 22". When the third boom section 9"' translates towards the extended position thereof (Figure 3b), the second conduit 17" gradually leaves the second channel 21", by flipping over. As the third boom section 9"' gradually approaches the extended position, the portion of the second conduit 17" which is flipped over, with respect to the completely retracted position of the third boom section, will get longer. The tubes and/or cables fixed inside the second conduit 17" will be similarly flipped over.
[0023] Figure 2 schematically illustrates the behavior of the flexible conduit 17 connected to the pair of boom sections 9' and 9" when the second boom section 9" switches from the retracted configuration to the extended configuration. The flexible conduit 17 (and also the tubes and/or wires contained in it) is illustrated by a broken line and is connected, on one side, to the distal end 20' of the first distal section and, on the other side, to the proximal end 19" of the second boom section 9", wherein the curvilinear length 22 is formed. Each boom section 9' and 9" comprises respective channels 21' and 21", to which the tubes and/or cables received in the flexible conduit in the portions wherein such flexible conduit is not provided (solid line) are fixed. Figure 2 illustrates the second boom section 9" when passes from the retracted position (a) to the extended position (b) with respect to the first boom section. In the intermediate positions (b, c, d), the portion of the conduit 17 received in the first channel 21' gets gradually shorter and flips over until it gradually leaves the first channel 21'. In the retracted position (a), the conduit 17 is received in the first channel 21' between the first 9' and second 9" boom sections, while, in the extended position, the flexible conduit 17 is substantially aligned with the second boom section 9". The curvilinear length 22 of the flexible conduit 17, when switching between the two configurations, of course is also displaced. Particularly, it is placed in proximity to the proximal end 19" of the second boom section 9", spaced from the distal end 20' of the first boom section, in the retracted position, while is placed in proximity to the distal end 20' of the first boom section 9", spaced from the proximal end 19" of the second boom section 9", in the extended position.
[0024] The crane according to the invention exploits the geometrical/kinematic behavior of the above described flexible conduits for measuring the extension of each boom section.
[0025] To this purpose, the crane 1 comprises a device 23 for measuring the extension of the extending boom 6, in turn comprising a plurality of flexible portions 24 integrally connectable to each flexible conduit 17 of each pair of boom sections. For example, the flexible portions 24 can be fixed inside the space defined by the links of the chains forming each flexible conduit 17. In this manner, the flexible portions 24 substantially follow the spatial trend of the flexible conduits when switching between the extended configuration and the retracted one of the pair of boom sections. One or more sensors 25 adapted to detect the flipping-over of the respective flexible portion are associated to each flexible portion 24. For example, such sensor 25 can comprise angular sensors or inertial platforms (adapted to determine the flipping-over by measuring the direction of the gravitational acceleration). In this manner, due to the flipping over of the flexible conduit 17, dependent, as said hereinbefore, on the relative position of the second boom section with respect to the first boom section in a pair of boom sections, also the flexible portions 24 flip over and such flipping-overs are detected by flipping-over sensors 25. By knowing the position of the sensor 25 in the respective flexible conduit 17 and the orientation thereof in the space, it is possible to determine how much the second boom section of each pair projects out. Of course, determining how long the boom sections project by a discrete number of flipping-over sensor 25 cannot be continuous, but will be also discrete. The higher the number of sensors 25 associated to each flexible portion 24 is, the more accurate the estimate of the axial extension will be. In other words, as the number of sensors 25 increases, the resolution of the measurement will also increase.
[0026] The principle underlying the measurement is schematically illustrated in Figure 4. Four flipping-over sensors 25', 25", 25"' and 25"" are associated to the flexible portion 24 of the measuring device 23, integral with the flexible conduit 17. In the shown retracted configuration, the first sensor 25' has a first orientation (↓), while the second 25", the third 25"' and fourth 25"" sensors have a second orientation (↑) opposite the first one. As the second boom section 9" gradually projects by moving towards the extended position:
- the second sensor 25" flips over, by taking the first orientation (↓), while the first sensor 25' keeps the first orientation (↓): the extension of the boom due to this pair of boom sections is determined as equal to the distance along the flexible portion 24 between the first 25' and second 25" sensors;
- the third sensor 25"' flips over, by taking the first orientation (↓), while the first 25' and second 25" sensors keep the first orientation (↓): the extension of the boom due to this pair of boom sections is determined as equal to the distance along the flexible portion 24 between the first 25' and third 25"' sensors;
- the fourth sensor 25"" flips over, by taking the first orientation (↓), while the first 25', second 25" and third 25"' sensors stay in the first orientation (↓): the extension of the boom due to this pair of boom sections is determined as equal to the distance along the flexible portion 24 between the first 25' and fourth sensors 25"". Such condition can correspond to the completely extended position of the second boom section 9".
[0027] Advantageously, the flexible portions 24 of the measuring device 23 are portions of a flexible cable extending from the first boom section, to the latter boom section of the extending boom 6. In addition to the flexible portions 24, moving with the flexible conduits 17, such cable comprises fixed portions 26 which can be also flexible (or also stiff) and which are integrally connected to the first boom section of each pair of following boom sections. For example, such fixed portions 26 can integrally be fixed to the channels 21. Therefore, the flexible portions 24 provided with the flipping-over sensors 25 are alternately positioned with respect to the fixed portions 26, according to what is schematically shown in Figure 4.
[0028] Since, as said, the extending boom 6 can be inclined with respect to the horizontal, the orientation of the flipping-over sensors 25 is evaluated with respect to the actual inclination of the extending boom (corresponding to the angle formed by the direction of the axial boom section of the boom sections with respect to the horizontal). Otherwise, the inclination of the extending boom 6 could be confused with a flipping-over of the flexible portion 24. Advantageously, to this purpose, the measuring device 23 comprises a main unit 27 connected to the first boom section of the extending boom, provided with a sensor 28 for measuring the absolute inclination of the extending boom 6. Such absolute inclination measured by the sensor 28, represents the angular reference of the flipping-over measured by the flipping-over sensors 25. For example, if the sensor 28 measures an absolute angle equal to 20°, a measurement of 20° of one of the sensors 25 corresponds to a first orientation, while a measurement of 200° (or of -160°) of one of the sensors 25 corresponds to the second orientation, in other words this orientation is flipped over with respect to the first orientation.
[0029] With reference to Figure 5, the measuring device 23 according to a possible embodiment is shown. It comprises the cable 29, with associated flipping-over sensors 25 (in this case there are three sensors) and the main unit 27 comprising the absolute inclination sensor 28. According to this embodiment, the device 23 is formed in a single piece, in other words the cable 29 is single and cannot be divided. According to a further possible embodiment, the cable 29 can comprise a plurality of separated and connectable parts, each of them comprising one or more flipping-over sensors 25. Figure 6 schematically illustrates one of said cable 29 portions, provided with connectors 30 for the connection to adjacent portions. In this manner, the measuring device 23 makes a system of flipping-over sensors 25 formed as a modular series. For example, if one of the sensors 25 fails, it is sufficient to substitute the modular portion where such failed sensor is inserted.
[0030] Advantageously, the measuring device 23 comprises a control unit 31 for commanding the device itself and configured for communicating with a main control unit (not shown in the figures) of the crane 1.
[0031] Particularly, the control unit 31 is configured for:
- associating to each of the flipping-over sensors 25 a progressive sequential value corresponding to the position of the flipping-over sensor with respect to the other flipping-over sensors of the measuring device 23. In this manner, each sensor 25 is uniquely identified based on the position thereof, also in case of a replacement thereof;
- associating to each identified sensor in the above way, a state corresponding to the orientation thereof. A first state corresponding to a first orientation (for example ↓. in Figure 4), or a second state corresponding to a second orientation flipped over with respect to the first one (for example ↑ in Figure 4) is associated to each sensor 25;
- preferably, associating to each of the flipping-over sensors 25 a fail state or a proper operation state.
[0032] Based on such information, knowing the position of each flipping-over sensor enables to determine, for each pair of boom sections of the extending boom 6, the length of the projected portion and therefore also of the overall projecting portion of the whole extending boom 6. Preferably, such operation is conducted by the main control unit of the crane, based on data received from the control unit 31 of the measuring device 23. As an alternative, such operation can be directly performed by the control unit 31.
[0033] Each of the flipping-over sensors 25 preferably comprises a luminous indicator 32 showing an operative state.
[0034] It is to be observed that, in the described embodiments, it is assumed that each boom section of the pair of boom sections is associated to a respective channel. Such situation is schematically shown in Figure 7, wherein in the shown pair of boom sections 18 the first boom section 9' is associated to the first channel 21' and the second boom 9" is associated to the second channel 21", wherein the flexible conduit 17 is integrally translatingly connected to the distal end 20' of the first boom section 9' - in this case corresponding to the distal end of the first channel 21' - and to the proximal end 19" of the second boom section 9" - in this case corresponding to the proximal end of the second channel 21". The broken lines 33' and 33" schematically represent mechanical connections between the first boom section 9' and first channel 21', and between the second boom section 9" and second channel 21", respectively. According to this variant, preferably the channels 21' and 21" have a longitudinal extension less than the one of the respective boom section 9' and 9".
[0035] According to an alternative embodiment of the invention, the pair of boom sections 18 further comprise an auxiliary boom section 34 interposed between the first boom section 9' and second boom section 9". Such variant is schematically illustrated in Figure 8. The auxiliary boom section 34 is translatingly movable with respect to the first boom section 9' between a retracted position and an extended position, and the second boom section 9" is translatingly movable with respect to the auxiliary boom section 34 between a retracted position and an extended position. When the auxiliary boom section 34 is placed in the retracted position with respect to the first boom section 9', and the second boom section 9" is placed in the retracted position with respect to the auxiliary boom section 34, the second boom section 9" is placed in the retracted position with respect to the first boom section 9'. When the auxiliary boom section 34 is placed in the extended position with respect to the first boom section 9' and the second boom section 9" is placed in the extended position with respect to the auxiliary boom section 34, the second boom section 9" is placed in the extended position with respect to the first boom section 9'. The auxiliary boom section 34 is devoid of channels and therefore the flexible conduit 17 is devoid of parts integrally translating with it, while the structure of the first 9' and second 9" boom sections substantially corresponds to the one described with reference to the embodiment in Figure 7. Particularly, the first boom section 9' is associated to the first channel 21' and the second boom 9" is associated to the second channel 21", wherein the flexible conduit 17 is translatingly integrally connected to the distal end 20' of the first boom section 21' - in this case corresponding to the distal end of the first channel 21'- and to the proximal end 19" of the second boom section 9" - in this case corresponding to the proximal end of the second channel 21". The broken lines 33' and 33" schematically illustrate mechanical connections between the first boom section 9' and first channel 21', and between the second boom section 9" and second channel 21", respectively. According to this variant, the channels 21' and 21" have preferably a longitudinal extension about equal to or slightly less than the one of the respective boom section 9' and 9". According to this variant, the measuring device is uncapable of distinguishing the respective projection of the auxiliary boom section 34 with respect to the first boom section 9', and of the second boom section 9" with respect to the auxiliary boom section 34, but it is capable of measuring the projection of the auxiliary boom section 34-second boom section 9" assembly with respect to the first boom section 9'.
[0036] From the above given description, a person skilled in the art can appreciate how a crane provided with the measuring device according to the invention enables to obtain the following advantages:
- a limited wear, with respect for example to a wireless system, consequently the maintenance is reduced since the parts of the measuring device are not substantially subjected to shocks;
- compactness, since the presence of the measuring device does not substantially alter the overall size;
- low cost, since the measuring device is based on a simple instrumentation;
- measuring is substantially independent from the extending boom bending, since the latter does not substantially alter the spatial orientation of the flipping-over sensors 25;
- possibility of determining the extension sequence of the extending boom by taking measurements on each pair of subsequent boom sections.
[0037] To the described embodiments of the crane according to the invention, a person skilled in the art, in order to meet specific contingent needs, can introduce plural additions, modifications, or substitutions of elements with other operatively equivalent, without falling out of the scope of the attached claims.
1. Crane (1) comprising:
- an extending boom (6) comprising at least one pair of boom sections (9', 9"), wherein said at least one pair of boom sections comprises:
- a first boom section (9') and a second boom section (9") translatingly movable with respect to the first boom section (9') between an extended position and a retracted position, wherein said first (9') and second sections (9") have each a proximal end (19) and a distal end (20);
- a flexible conduit (17) integrally translatingly connected to the distal end (20') of the first boom section (9') and to the proximal end (19") of the second boom section (9"), such that during the passages from the extended and retracted positions of the second boom section (9"), the portion of the flexible conduit (17) comprised between the distal end (20') of the first boom section (9') and the proximal end (19") of the second boom section (9") gradually flips over;
- a device (23) for measuring the extension of the extending boom (6);
characterized in that said device (23) for measuring the extension of the extending boom (6) comprises at least one flexible portion (24) integral with the flexible conduit (17) of the at least one pair of boom sections (9', 9"), and at least one sensor (25) adapted to detect the flipping-over of said at least one flexible portion (24).2. Crane (1) according to claim 1, wherein said at least one flipping-over sensor (25)
comprises an angular sensor and/or an inertial platform.
3. Crane (1) according to claim 1 or 2, wherein said device (23) for measuring the extension
of the extending boom (6) comprises a cable (29) extending from the first to the last
extension booms of the extending boom (6), wherein said cable (29) comprises at least
one stationary portion (26) integrally connected to the first boom section (9') of
said at least one pair of boom sections.
4. Crane (1) according to claim 3, wherein said cable (29) comprises a plurality of parts
separated from each other, connectable by connectors (30), each of said separated
parts comprising one or more of said flipping-over sensors (25).
5. Crane (1) according to any of the preceding claims, wherein said device (23) for measuring
the extension of the extending boom (6) comprises a sensor (28) for measuring the
absolute inclination of the extending boom (6), the flipping-over measured by said
flipping-over sensors (25) being referred to said absolute inclination of the extending
boom (6), measured by said absolute inclination sensor (28).
6. Crane (1) according to any of the preceding claims, wherein each of said flipping-over
sensors (25) is associated to a first state, corresponding to a first orientation,
and a second state corresponding to a second orientation flipped over with respect
to the first orientation.
7. Crane (1) according to any of the preceding claims, wherein to each of said flipping-over
sensors (25) is associated a progressive sequential value corresponding to the position
of the flipping-over sensor with respect to the other flipping-over sensors of the
measuring device (23).
8. Crane (1) according to claims 6 and 7, wherein said measuring device (23) comprises
a control unit (31) configured for gathering, for each flipping-sensor over (25) identified
by said progressive sequential value, the respective state corresponding to the orientation.
9. Crane (1) according to claim 8, further comprising a main control unit of the crane
communicating with said control unit (31) of the measuring device (23), said main
control unit of the crane being configured for calculating the overall extension of
the extending boom (6), and the partial extension of the extending boom due to the
extension of the at least one pair of boom sections from the state corresponding to
the orientation of each sensor identified by said progressive sequential value supplied
by the control unit (31) of the measuring device (23).
10. Crane (1) according to any of the preceding claims, wherein said pair of boom sections
(18) further comprises an auxiliary boom section (34) interposed between the first
(9') and the second (9") boom sections, wherein said auxiliary boom section (34) is
translatingly movable with respect to the first boom section (9') between a retracted
position and an extended position, and the second boom section (9") is translatingly
movable with respect to the auxiliary boom section (34) between a retracted position
and an extended position, such that:
- when the auxiliary boom section (34) is in the retracted position with respect to the first boom section (9'), and the second boom section (9") is in the retracted position with respect to the auxiliary boom section (34), the second boom section (9") is in the retracted position with respect to the first boom section (9');
- when the auxiliary boom section (34) is in the extended position with respect to the first boom section (9'), and the second boom section (9") is in the extended position with respect to the auxiliary boom section (34), the second boom section (9") is in the extended position with respect to the first boom extension (9').