Lifting device equipped with auxiliary devices to prevent boom tipping in the event of sudden loss of load.

Abstract

A lifting device with a force-absorbing base is described, to which a boom with a lifting cable is tiltably connected for lifting a load in a substantially vertical direction. The lifting device includes an auxiliary device to resist boom tipping in the event of sudden loss of load. The auxiliary device is connected to the base of the lifting device and provides a contact surface that is in permanent contact with, or in the event of tipping, contact with, the contact surface of the boom. The auxiliary device also includes a drive and control system configured to prevent boom movement when a predetermined force between the contact surfaces exceeds the force due to boom tipping. The described auxiliary device can be a separate unit or can be mounted on the lifting device.

Description

Technical Field

[0001] This invention relates to a lifting device having a force-absorbing base to which a boom is obliquely connected, the boom having a lifting cable for lifting a load in a substantially vertical direction, wherein the lifting device also includes an auxiliary device for resisting boom tipping in the event of sudden loss of load, for example, due to the breakage of the lifting cable. The invention also relates to an auxiliary device for resisting boom tipping in the event of sudden loss of load.

[0002] This invention can, in principle, be applied to lifting any object, both on land (onshore) and at sea (offshore). However, the advantages of this invention become most apparent when lifting objects offshore. A typical application, for example, involves the offshore laying of wind turbine foundations. Background Technology

[0003] Lifting devices for raising loads typically include a force-absorbing base, for example, a so-called A-frame forming part of the base, and a tiltable boom about a horizontal axis connected to the base. The base is configured to transfer forces acting on the boom to the ground, such as the deck and hull of a ship. The pivoting connection between the base and the boom allows the boom to tilt in a vertical plane between a maximum inward luffing position and a maximum outward luffing position via a so-called luffing cable. In the maximum inward luffing position, the boom is positioned at its minimum angle to the vertical, and in the maximum outward luffing position, the boom is positioned at its maximum angle to the vertical. Thus, the operating angle of the boom lies between these two positions. Attached to the boom is a lifting cable to which a load can be attached for lifting, wherein the lifting cable extends in a substantially vertical direction.

[0004] When lifting a load, it is possible for the boom to suddenly drop backward and be forced beyond its maximum luffing position. This tipping of the boom can occur, for example, in the event of sudden loss of load, such as due to the breakage of the lifting cable, or in the event of the load suddenly detaching from the lifting cable. When lifting a load, a force opposite to the gravity applied to the load is applied to the lifting system. This force is specifically applied to the lifting cable, boom, and luffing cable. Compared to the two cables, the boom is relatively rigid and does not deform much. However, elastic energy will accumulate in the lifting cable and luffing cable. In the event of a so-called sudden loss of load, the boom tends to “shoot” out of the load due to the sudden release of the elastic energy accumulated in the luffing cable. If the lifting system is located on the ship and the boom protrudes laterally, for example to the starboard side (SB), ballast water can be loaded on the opposite port side (PS) to achieve balance. In this case, in the event of sudden loss of load, the balance is broken, and the ship will begin to roll away from the load, in this case to the PS. As a result, the boom rotates around its base and luffs further. This amplifies the tipping effect, and the boom could even exceed its vertical balance point and self-destruct. This situation is, of course, highly undesirable.

[0005] It should be noted that the term "tipping" is not limited to the aforementioned movement of the boom beyond its vertical balance point. Even if the boom does not "tipping" in this way, and the luffing cable becomes slack due to the sudden backward movement of the boom (away from the load), the luffing cable may subsequently be tightened again by a sudden force. The luffing cable, and the boom in particular, can be overloaded by such a lifting load. This phenomenon also falls under the category of "tipping" and must be avoided.

[0006] One object of the present invention is to provide an auxiliary device for resisting boom tipping in the event of sudden loss of load, and a lifting device equipped with the auxiliary device. This avoids damage associated with tipping, or at least reduces the risk of tipping. Summary of the Invention

[0007] This objective is achieved by providing a lifting device having the features of claim 1. The lifting device of the present invention includes a force-absorbing base to which a boom is obliquely connected, the boom having a lifting cable for lifting a load in a substantially vertical direction, and the lifting device further includes an auxiliary device for resisting boom tipping in the event of sudden loss of load, for example, due to the breakage of the lifting cable. The auxiliary device is connected to the base of the lifting device and provides a contact surface that contacts, or in the event of tipping, the contact surface of the boom. The auxiliary device also includes a drive and control system configured to prevent or block boom movement when a predetermined force between the contact surfaces exceeds the force due to boom tipping.

[0008] In this embodiment, the contact surface of the auxiliary device contacts the contact surface of the boom, and during normal boom movement, the boom applies a force to the auxiliary device less than a predetermined maximum force. The contact surface of the auxiliary device then freely displaces along with the boom as it moves. In the event of a tipping over, the force applied to the auxiliary device will exceed the predetermined maximum force. Subsequently, the drive and control system will ensure that movement of the contact surface is prevented, prohibited, or blocked, for example, by a blocking means suitable for this purpose. This prevents the boom from tipping over.

[0009] In this embodiment, in the event of a tipping, the contact surface of the auxiliary device comes into contact with the contact surface of the boom, while the boom exerts virtually no force on the auxiliary device during normal movement. Because a predetermined force is not exceeded (which in this embodiment may have a different value than described above, or even be zero), the contact surface of the auxiliary device will freely move together with the boom and follow its movement. In the event of a tipping, the boom will come into contact with the contact surface of the auxiliary device. Subsequently, the force applied to the auxiliary device exceeds the predetermined force, thereby the drive and control system will ensure that the movement of the contact surface is prevented, prohibited, or blocked, for example, by a blocking means. This prevents the boom from tipping.

[0010] In an embodiment of the lifting device, an auxiliary device, more specifically a movable part of the auxiliary device, is connected to the boom, preferably at the outer end of the movable part, where the contact surface of the auxiliary device contacts the contact surface of the boom.

[0011] In another embodiment of the lifting device, the drive and control system is configured to keep the contact surfaces of the auxiliary device and the contact surfaces of the boom at a small distance from each other, so that the boom can only accelerate to a limited extent during tipping.

[0012] The auxiliary device of this invention can stop the boom immediately (or within a relatively short time) after a sudden loss of load. This prevents the boom from accelerating or accumulating kinetic energy. The auxiliary device is connected to a base so as to transfer the force caused by the boom's rebound force to the ground connected to the base, such as the hull of a ship.

[0013] This lifting device can be used on shore or on any type of vessel, with the advantages of the invention becoming particularly apparent when used on a monocoque crane vessel. The auxiliary device is further configured to stop the (accelerated) boom in a position between the maximum inward luffing position and the maximum outward luffing position. Providing only a portion of this range is sufficient, for example, a position midway between the maximum inward luffing position and the maximum outward luffing position.

[0014] According to an embodiment of the invention, the contact surfaces of the auxiliary device are maintained at a small distance from the contact surfaces of the boom by a drive and control system, such that the boom can only accelerate to a limited extent during tipping. Therefore, in this embodiment, the auxiliary device is not connected to the boom. This has the advantage that any movement of the boom during normal use—such as twisting or bending—will not be transmitted to the auxiliary device. The auxiliary device can therefore be made in a relatively lightweight form.

[0015] A small mutual distance can be selected within certain limits. Practical embodiments involve lifting devices in which the mutual distance between the two contact surfaces is maintained between a minimum and a maximum distance.

[0016] In suitable embodiments, the lifting device is configured such that the minimum distance is between 1 and 10 mm, and the maximum distance is between 5 and 30 mm. During normal use of the boom (and therefore in the absence of tipping), the contact surface of the auxiliary device is thus kept at a distance between 1 and 30 mm.

[0017] More advantageously, the lifting device is characterized in that the mutual distance between the two contact surfaces is kept constant by a drive and control system. For example, this can be controlled based on vector distance. Further improved embodiments of the lifting device include a drive and control system configured to control the mutual distance in the horizontal direction, preferably keeping it within limits, and more preferably keeping it constant.

[0018] A suitable embodiment of the invention provides a lifting device in which the boom has two legs and an auxiliary device provides two contact surfaces that, in the event of tipping, contact the two contact surfaces with two corresponding contact surfaces of the boom.

[0019] In embodiments of the invention, the lifting device may also be characterized in that the boom is tiltable about a tilting point, and the contact surface of the boom is located at at least 2 / 5 of the length of the boom from the tilting point, and more preferably at least halfway. This makes it possible to limit the force acting on the auxiliary device in the event of tipping.

[0020] In other embodiments, the base of the lifting device includes an A-shaped frame, and an auxiliary device is connected to the A-shaped frame of the lifting device, preferably on the upper side of the A-frame.

[0021] The auxiliary device can take any suitable form, as long as it provides a contact surface for the boom and can stop the boom in the event of a sudden backward movement away from the load.

[0022] The actual embodiment relates to a lifting device, wherein the auxiliary device includes a frame, a support beam is attached to the frame, the support beam is horizontally displaceable between end positions using a drive system, and the end faces of the support beam form a contact surface.

[0023] In embodiments, a particularly suitable drive system includes a rack and pinion system comprising a rack driven by gears. The outer end of the rack provides a contact surface with the boom. The rack and pinion system is designed to absorb forces acting on the auxiliary devices by accelerating the boom in the event of a tilt, thereby resisting movement of the boom.

[0024] In a suitable embodiment, the lifting device is characterized in that when the torque exceeds a predetermined maximum due to boom tipping, the gear prevents boom movement by means of a blocking mechanism (e.g., a brake acting on the gear). The gear may be driven, for example, by an electric drive, such as an electric motor. If the drive torque exceeds a predetermined torque (which comes from a predetermined force) in the event of tipping, a brake on the electric drive is activated, thereby blocking and impeding the drive. A suitable brake may, for example, comprise a plurality of plates held apart by an electromagnet. Activation of the brake deactivates the electromagnet, causing springs to "bump" the plates together. Clearly, multiple options exist, and the invention is not limited to this particular embodiment.

[0025] Rack and pinion systems are known, for example, for use in jack-up platforms, particularly for moving the legs of such platforms up and down. Rack and pinion systems are capable of transmitting relatively large forces.

[0026] To enable automatic adjustment of the distance between the contact surfaces, in this embodiment, the lifting device is equipped with a control system that includes a measuring means for measuring the distance between the two contact surfaces. In principle, any measuring means suitable for this purpose can be used. Optical measuring means are preferably included.

[0027] In one embodiment, the measuring means is positioned at the contact surface of the auxiliary device.

[0028] The auxiliary device provided on the lifting device can be integrated with the lifting device. However, according to another aspect of the invention, an auxiliary device is provided that is independent and can be placed on the lifting device. This auxiliary device for resisting boom tipping in the event of sudden loss of load can be connected to the base of the lifting device and provides a contact surface that contacts the contact surface of the boom in the event of tipping. The auxiliary device further includes a drive and control system configured to maintain a small mutual distance between the contact surface of the auxiliary device and the contact surface of the boom, such that the boom can only accelerate to a limited extent during tipping.

[0029] Possible embodiments of the auxiliary device have been described in detail above, and reference is sufficient to follow that description.

[0030] When auxiliary devices are used in conjunction with lifting devices for lifting offshore loads (such as components of wind turbines), the work is preferably carried out from a (floating) vessel or jack-up platform, which provides greater stability. Attached Figure Description

[0031] Further embodiments, their features, and additional advantages will be further described with reference to the accompanying drawings, wherein:

[0032] Figure 1 This is an isometric side view of the lifting device according to an embodiment of the present invention;

[0033] Figure 2 yes Figure 1 An isometric rear view showing details of the lifting device;

[0034] Figure 3 This is a schematic top view of a ship, on which a lifting device according to an embodiment of the present invention is installed;

[0035] Figures 4A-4C This is a side view of a lifting device with auxiliary equipment according to an embodiment of the present invention at different tilt angles;

[0036] Figures 5A-5C yes Figures 4A-4C Details of the side view; and, finally

[0037] Figure 6 This is a cross-section of the auxiliary device according to an embodiment of the present invention. Detailed Implementation

[0038] Identical or similar parts are referred to using the same reference numerals in the accompanying drawings.

[0039] Figure 1 A lifting device 1 according to the invention is shown. Among other things, this embodiment includes a force-absorbing base, which itself comprises a bottom frame 11 and an A-frame 12. A boom 10 is tiltably mounted on the force-absorbing base. A luffing cable 13 is further configured to start from approximately the height of the bottom frame 11, pass over the upper outer end 14 of the A-frame 12, and extend at least to the upper outer end 14 of the boom 10, for lifting a load in a substantially vertical direction. The luffing cable 13 may also be tensioned along other paths. The lifting device 1 is optionally also rotatable, either because the bottom frame 11 is a rotatable bottom frame, or because the bottom frame 11 is mounted on another rotatable element.

[0040] This type of lifting device is prone to tipping over, which can occur when there is a sudden loss of load. For example, this can happen when the lifting cable breaks, when the hook or other means of connection between the lifting cable and the load is disconnected, or when the load itself partially or completely collapses.

[0041] Tilting includes any unintended movement of the boom 10 due to the release of tension accumulated on it. In the event of a severe tilt, there is a risk that the boom 10 may end up in a fully upright position, and the remaining momentum may cause the boom 10, or a portion thereof, to tilt beyond that point, after which the portion tilted beyond the upright point will fall backward. This is also known as a complete tilt. In a less severe but still serious tilt, there is a risk that the boom 10 may become only partially more upright and the luffing cable 13 may become slack. As the boom 10 then falls forward, tension will return to the luffing cable 13 with a sudden force. This is also known as a snatch load. Like a complete tilt, a snatch load has catastrophic consequences.

[0042] therefore, Figure 1 Further illustration shows that the lifting device 1 is equipped with an auxiliary device 3, which, in this embodiment, is disposed at the upper outer end of the A-shaped frame 12. The auxiliary device 3 can also be mounted on the lower part of the A-shaped frame 12 or on different parts of the force-absorbing base. In particular, among other things, the auxiliary device 3 includes a frame 31 on which a rack and pinion system 32 and a guiding device 34 are disposed. In this embodiment, the rack and pinion system 32 and the guiding device 34 form a drive and control system, and in other embodiments, the drive and control system also includes different components. Support beams 30 are disposed in each rack and pinion system 32. The support beams 30 provide a contact surface 33 toward the outer end of the boom 10. The support beams 30 can be displaced substantially horizontally between end positions by a drive and control system (in this embodiment, by the rack and pinion system 32).

[0043] A corresponding number of contact surfaces 33' can be specified on the boom 10, which are the positions where the contact surfaces 33 contact the boom 10 in the event of a sudden loss of load.

[0044] To prevent the boom 10 from gaining momentum during the tilting process, i.e., to prevent the boom 10 from accelerating too quickly, the distance between the contact surfaces 33 and 33' is kept small. In this embodiment, the drive system is capable of displacing the contact surface 33.

[0045] Once the contact surfaces 33, 33' begin to contact each other, a portion of the boom's momentum is absorbed by the auxiliary device 3. This portion is proportional to the portion of the boom 10 located below the contact surface 33'. The remaining momentum of the boom 10 that is not absorbed by the contact surface 33 compromises the integrity of the boom 10. Despite the auxiliary device 3, the boom 10 may still tip over if the remaining momentum is too large for its integrity. Therefore, it is preferable that the contact surface 33' is located as high as possible on the boom 10. In a particular embodiment, these contact surfaces on the boom 10 are thus located at at least 2 / 5 of the length of the boom 10, and preferably at at least half the height of the boom 10.

[0046] The orientation device 34 controls the orientation angle of the support beam 30 relative to the boom 10 from the frame 31. Orienting the support beam 30 in this way allows the contact surface 33' to be independent of the tilt angle of the boom 10. The advantage is that if reinforcement of the contact surface of the boom 10 is desired, only a small portion of the boom 10 needs to be reinforced. Another advantage of orienting the contact surface 33 relative to the boom 10 in this way is that when the contact surfaces 33, 33' contact each other, the surface is as close to the ground as possible – or in other words, the contact surfaces 33, 33' contact each other in the most forward possible manner. This is desirable because if the support beam 30 contacts the boom 10 at an angle, it will absorb less momentum from the boom 10 and / or cause undesirable damage to the boom 10.

[0047] The illustrated embodiment of the auxiliary device 3 includes two contact surfaces 33. Only one, or three or more contact surfaces may also be provided. The desired number of contact surfaces is determined, for example, based on the number of legs of the boom 10. In the illustrated embodiment, the boom 10 has two legs, although the boom 10 may also include only one leg.

[0048] In the illustrated embodiment, the base is provided with an A-shaped frame 12. Two slightly inclined columns and multiple beams connecting the columns are shown in the figure. The A-shaped frame may also optionally include two rear legs extending further rearward from the top of the A-shaped frame. Other frame forms that fulfill this function may also be provided.

[0049] Figure 2 Details of the lifting device 1 are shown, again illustrating the boom 10, A-frame 12, and luffing cable 13. The figure further illustrates the structure of the frame 31, in which two support beams 30 are positioned on it. For each support beam, the frame 31 has a horizontal leg 31A and a slanted leg 31B, wherein these legs are attached to each other at their projecting outer ends 31D and connected to the A-frame 12 at their opposing outer ends 31C and 31E.

[0050] Figure 1and Figure 2 An embodiment of the lifting device 1 is shown, adapted to lift a load on its first side. In this embodiment, the boom 10 is mounted on a base so that it can tilt toward this first side of the lifting device 1. As seen from the boom 10, the side to which the boom can tilt is also the first side of the boom configured for lifting. When the auxiliary device 3 is not provided, when the load is suddenly released, the boom 10 will accelerate in the opposite direction to the direction in which the boom 10 can tilt.

[0051] Therefore, in this embodiment, the auxiliary device 3 is preferably disposed on the second side of the boom 10, opposite to the first side, and the auxiliary device 3, in particular the contact surface 33, is thus located in the path of the boom 10 in the event of a sudden loss of load.

[0052] Figure 3 A top view of vessel 2 is shown, on which the lifting device 1 according to the invention is disposed. In this embodiment, the lifting device 1 can also rotate. In this embodiment, the boom 10 is therefore configured to lift loads in an area extending from an inner diameter 40 (where the boom 10 is positioned as vertically as possible) and an outer diameter 41 (where the boom 10 is tilted as forward as possible). The auxiliary device 3 makes it possible to avoid the boom 10 tipping over in the event of a sudden loss of load during lifting in the low-risk area 42. As mentioned above, the boom 10 can be configured to tilt beyond the point where the auxiliary device 3 can prevent tipping, leaving area 43 where the risk typically exists.

[0053] Figures 4A-4C The above reference is shown. Figure 1 and Figure 2 A side view of the described lifting device 1. Specifically, Figure 4A -C again shows the boom 10, the A-frame 12, and the auxiliary device 3, wherein the auxiliary device 3 in this embodiment again includes a frame 31, drive and control systems 32, 34, and a support beam 30, which includes a contact surface 33. Figure 5A -C shows details of these side views, where figures with the same letter markings correspond to each other.

[0054] In the side view shown, the boom 10 is... Figure 4A The boom 10 has a maximum outreach. In this case, when the boom 10 tilts beyond the first tilt angle, the auxiliary device 3 is no longer able to maintain a small distance between the contact surfaces. Therefore, the effectiveness of the auxiliary device 3 in preventing the boom 10 from tipping over will decrease proportionally to the degree to which the boom 10 tilts beyond that angle. Therefore, a second tilt angle can be specified, and when the boom 10 tilts beyond this second tilt angle, the auxiliary device 3 will no longer be able to prevent the boom 10 from tipping over in the event of a sudden loss of load.

[0055] Figure 5AAs shown in more detail, in order to keep the distance between the contact surface 33 and the relative contact surface of the boom 10 small, the support beam 30 extends to its limit position. In this case, the orientation system 34 has oriented the support beam 30 downward at the maximum possible angle.

[0056] exist Figure 4B The middle boom 10 has a ratio Figure 4A A smaller outreach distance. In a preferred embodiment, the distance between the two contact surfaces remains constant when the boom 10 is adjusted. For example, when the boom 10 is adjusted from such a position... Figure 4A The tilt angle shown was adjusted to, as Figure 3 When the tilt angle is smaller as shown in B.

[0057] To achieve this, the lifting device 1 is equipped with a measuring means for measuring the mutual distance between the two contact surfaces. For example, such a measuring means may include optical measuring means, specifically, it may be mounted on the frame 31 or on the support beam 30. From the frame 31, the absolute tilt angle of the boom 10 can be measured, and it can be estimated how far the support beam 30 must extend to maintain a small mutual distance between the contact surfaces. From the support beam 30, the relative distance between the boom 10 and the measuring means can be measured. If these measuring means are fixedly mounted on the support beam 30, the distance between the contact surface 33 and the boom 10 can be derived and thus kept constant by shifting the support beam 30 using a drive and control system 32 controlled by the measuring means.

[0058] Figure 5B The diagram shows in more detail that the support beam 30 has been displaced together with the boom 10 to maintain a small distance between the contact surface 33 and the relative contact surface of the boom 10. The orientation angle of the support beam 30 relative to the boom 10 has been reduced by the orientation system 34.

[0059] In the side view shown, the boom 10 is... Figure 4C The minimum overhang distance is maintained in each of these embodiments. The mutual distance between the two contact surfaces is maintained between a minimum and a maximum distance. The minimum distance is, for example, between 1 and 5 mm, and the maximum distance is, for example, between 5 and 10 mm. This mutual distance primarily relates to the mutual distance in the horizontal direction.

[0060] Figure 5C Further details show that the support beam 30 has been moved again in conjunction with the boom 10 via the drive and control systems 32, 34 to maintain a small distance between the contact surface 33 and the relative contact surface of the boom 10. The orientation angle of the support beam 30 relative to the boom 10 has also been reduced, and the support beam 30 is essentially horizontal in this position.

[0061] Figure 6A cross-section of an embodiment of the auxiliary device 3 according to the invention is shown. Again, the lifting device 1 includes a boom 10, an A-shaped frame 12 as part of a force-absorbing base, and the auxiliary device 3. In this embodiment, the rack and pinion system 32 includes a gear 37 and a rack 36 disposed on a support beam 30. When the gear 37 rotates, the support beam 30 is displaced in a desired direction via the rack 36. As previously described, this is done to maintain a small distance between the contact surfaces 33, 33'.

[0062] However, in the event of a rollover, it is desirable that the support beam 30 does not move, or moves very little, relative to the frame 31 connected to the force-absorbing base. Therefore, in a preferred embodiment, the rack and pinion system 32 is provided with a blocking means that resists any movement of the support beam 30 relative to the horizontal leg 31A in the event of a rollover. It should also be understood that in this embodiment, the horizontal leg 31A is made heavier than the inclined leg 31B, so that the risk of collapse of the horizontal leg 31A is minimized when the contact surfaces 33, 33' come into contact.

[0063] Once the support beam 30 stops moving, i.e., when the boom 10 has a constant tilt angle, the blocking means can, for example, prevent the support beam 30 from moving. In this case, the support beam 30 is preventively blocked, and in the event of a tipping, it will be blocked much more frequently. However, the tilt angle of the boom 10 is often not constant; this is also because the boom 10 is tilted for reasons other than the lifting device 1. In the case of a slight tilt or twist of the boom 10, for example due to wind, it is still desirable to keep the distance between the contact surfaces 33, 33' small. Therefore, it is possible for the support beam 30 to adjust frequently, in which case the support beams 30 will therefore find that they do not block at the same frequency. In a preferred embodiment, the rack and pinion system 32 is therefore provided with a force detection means configured to detect whether an external force is applied to the support beam 30 (e.g., from the direction of the boom 10) and control the blocking means to block the support beam 30.

Claims

1. A lifting device having a force-absorbing base, a boom tiltably connected to the force-absorbing base, the boom having a lifting cable for lifting a load in a substantially vertical direction, wherein the lifting device further includes an auxiliary device for resisting the tipping of the boom in the event of sudden loss of load, wherein the auxiliary device is connected to the base of the lifting device and provides a contact surface that contacts the contact surface of the boom or, in the event of tipping, the contact surface of the boom, and the auxiliary device further includes a drive and control system configured to prevent the boom from moving when a predetermined force between the contact surfaces is exceeded due to the tipping of the boom; The drive and control system is configured to cause the contact surface of the auxiliary device to shift together with and follow the normal movement of the boom, so as to keep the contact surface of the auxiliary device and the contact surface of the boom at a small distance from each other, so that the boom can only accelerate to a limited extent during the overturning.

2. The lifting device according to claim 1, wherein by connecting the auxiliary device to the boom, the contact surface of the auxiliary device contacts the contact surface of the boom.

3. The lifting device according to claim 1, wherein the mutual distance between the two contact surfaces is maintained between a minimum and a maximum distance.

4. The lifting device according to claim 3, wherein the minimum distance is between 1 and 10 mm, and the maximum distance is between 5 and 30 mm.

5. The lifting device according to any one of claims 3 to 4, wherein the mutual distance between the two contact surfaces remains constant.

6. The lifting device according to any one of claims 3 to 4, wherein the mutual distance is the mutual distance in the horizontal direction.

7. The lifting device according to any one of claims 1 to 4, wherein the drive and control system is configured to displace the contact surface of the auxiliary device in the vertical direction such that when the boom is tilted, the contact surface of the auxiliary device remains opposite to the contact surface of the boom.

8. The lifting device according to any one of claims 1 to 4, wherein the boom has two legs and the auxiliary device provides two contact surfaces that contact corresponding contact surfaces of the boom, or, in the event of tipping, contact two corresponding contact surfaces of the boom.

9. The lifting device according to any one of claims 1 to 4, wherein the boom is tiltable about the tilt point, and the contact surface of the boom is located at at least 2 / 5 of the length of the boom from the tilt point.

10. The lifting device according to any one of claims 1 to 4, wherein the base includes an A-shaped frame of the lifting device, and the auxiliary device is connected to the A-shaped frame of the lifting device.

11. The lifting device according to claim 10, wherein the auxiliary device is connected to the upper side of the A-shaped frame.

12. The lifting device according to any one of claims 1 to 4, wherein the auxiliary device includes a frame, a support beam attached to the frame, the support beam being horizontally displaceable between end positions by means of a drive system, wherein the end faces of the support beam form a contact surface.

13. The lifting device according to any one of claims 1 to 4, wherein the drive system comprises a rack and pinion system, the rack and pinion system comprising a rack driven by a gear.

14. The lifting device according to claim 13, wherein when the predetermined torque is exceeded due to boom tilting, the gear prevents the boom from moving by the action of a brake on the gear.

15. The lifting device according to any one of claims 1 to 4, wherein the control system includes a measuring means for measuring the mutual distance between the two contact surfaces.

16. The lifting device according to claim 15, wherein the measuring means is located at the contact surface of the auxiliary device.

17. The lifting device according to claim 15, wherein the measuring means includes optical measuring means.

18. An auxiliary device for resisting boom tipping in the event of sudden loss of load, wherein the auxiliary device is connectable to the base of the lifting device and provides a contact surface that contacts the contact surface of the boom or, in the event of tipping, the contact surface of the boom, and the auxiliary device further includes a drive and control system configured to prevent boom movement when a predetermined force between the contact surfaces exceeds the force due to boom tipping. The drive and control system is configured to cause the contact surface of the auxiliary device to shift together with and follow the normal movement of the boom, so as to keep the contact surface of the auxiliary device and the contact surface of the boom at a small distance from each other, so that the boom can only accelerate to a limited extent during the overturning.

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