Crane steering system including an additional hydraulic braking device

Abstract

A slewing system (1) for controlling the orientation of a rotating part (9) of a crane, said slewing system (1) comprising at least: - a slewing geared motor (13) comprising a slewing motor (14) having a drive shaft, and a slewing gearbox (16) coupled to the drive shaft (15), the drive shaft (15) being able to rotate in two directions, namely clockwise and counterclockwise; - a main slewing brake (18) capable of being deactivated for weathervaning of the rotating part (9); and - an additional braking device (2) capable of being activated when weathervaning of the rotating part to exert on the drive shaft a braking torque opposing a slewing torque exerted by the rotating part (9) on the drive shaft (15), wherein the additional braking device is a hydraulic device. Figure 1

Description

Title of the invention: Orientation system for a crane comprising an additional hydraulic braking device. Technical field

[0001] The invention relates to a slewing system for controlling the orientation of a rotating part of a crane, and to a crane comprising a rotating part controlled in orientation by such a slewing system.

[0002] It relates more particularly to an orientation system allowing the rotating part of the crane to be put into weathervane mode, and which is equipped with an additional braking device capable of being activated when the rotating part is put into weathervane mode in order to exert a braking torque on it preventing an uncontrolled rotation of the rotating part when it is put into weathervane mode.

[0003] The invention finds a favorite, but not limiting, application in the field of tower cranes and modular cranes. Previous technique

[0004] In a known manner, a crane, and in particular a tower crane, comprises a mast (also called a tower or pylon) extending vertically, and a rotating part mounted rotatably on the top of the mast around a vertical orientation axis; this rotation of the rotating part around the orientation axis is called orientation in the field of cranes.

[0005] The rotating part comprises a boom from which the load is suspended by means of a lifting cable. The boom may be a distributing boom (on which a distribution trolley can be moved in translation) and / or a lifting or tilting boom (movable between a lowered horizontal position and raised positions inclined relative to the horizontal). The rotating part may also include a counter-jib, which extends diametrically opposite the boom with respect to the axis of rotation, and which is generally equipped with a ballast.

[0006] The orientation of the rotating part, in other words its rotation around the orientation axis, is controlled by a slewing system. This slewing system conventionally comprises a slewing ring whose function is to pivotally connect the rotating part to the top of the crane mast. This slewing ring consists of two concentric rings, with a fixed ring connected to the top of the mast and a movable ring attached to the rotating part, between which cylindrical balls or rollers are mounted.

[0007] The orientation system further comprises, for controlling the rotation of the rotating part thus kinematically connected to the mast, at least one orientation geared motor mounted on this rotating part. This orientation geared motor comprises at least one orientation motor coupled to a reduction gear and driving in rotation a vertical axis pinion which meshes with a toothed wheel machined into the fixed ring of the orientation slewing ring. Depending on the mechanical power to be transmitted to rotate the rotating part, it is possible to provide one or more geared motors on the rotating part.

[0008] The slewing geared motor usually has an internal brake, here called the main slewing brake, which is controlled by an electromagnet. When the slewing geared motor is stopped, the electromagnet's coil is not electrically energized, and a braking torque is applied to prevent the rotating part from rotating. Conversely, when the electromagnet is electrically energized, no braking torque is applied by this main slewing brake. If there are multiple slewing geared motors, at least one of them is equipped with such a main slewing brake, which is applied during the crane's operating periods.

[0009] Thus, this main slewing brake is designed to be deactivated when the rotating section is in weathervane mode, that is, when the crane is "out of service," outside of its working periods. This weathervane mode means that the slewing gear motor is disengaged to allow the rotating section to orient itself freely according to the wind direction. The counterweight jib then positions itself against the wind, while the boom orients itself in the direction of the wind, because the surface area of ​​the boom exposed to the wind is greater than that of the counterweight jib. In operation, to allow the crane to weathervane, the crane operator deactivates the main slewing brake when leaving their workstation.

[0010] However, the crane is sometimes installed in a disturbed environment in which wind conditions are particular or even extreme, generally due to the environment of the site such as the presence of nearby buildings or the proximity of a cliff or in a narrow valley, to the point that the rotating part of the crane can enter into unstable states, with uncontrolled rotation of the rotating part.

[0011] For example, the speed and force of the wind striking the counter-jib may be very different from the speed and force of the wind simultaneously striking the jib. This difference between the rotational torque applied to the jib and the rotational torque applied to the counter-jib can then become much greater than the frictional torque of the slewing ring, so that the rotating part of the crane, instead of aligning itself with the wind, will begin to rotate in a certain direction, without stopping. Thus, the crane is in an unstable state of autorotation (also called a state of autogyration), in which the rotating part fails to weathervane. correctly, and is set into an uncontrolled rotation. In such an unstable state, there is a risk of the crane falling, especially if a gust of wind strikes the rotating part when that part is oriented perpendicular to the wind direction.

[0012] To prevent uncontrolled rotation of the rotating part of the crane when it is installed on such a site, which is subject to turbulent winds, and thus to avoid the risk of the crane falling, a solution has already been proposed in document EP2025637. This solution consists of inserting an additional brake into the slewing mechanism. When the crane is put into weathervane mode, this brake exerts a permanent braking torque sufficient to prevent uncontrolled rotation of the rotating part, while still allowing the weathervane to be activated. However, this solution is impractical to implement.

[0013] It is also known from document EP2123592 to employ additional braking means suitable for being activated when the crane is taken out of service to exert a braking torque on the rotating part of the crane preventing uncontrolled rotation of this rotating part when turning, where such additional braking means are incorporated in the slewing gearmotor or in one of the slewing gearmotors, in the form of an internal auxiliary brake interposed between the motor and the gearbox.As described in this document, this internal auxiliary brake, interposed between the motor and the reducer, is a single disc brake controlled by an electromagnet. This brake is electrically powered so as not to impede the rotation of the rotating part of the crane when the crane is in operation, but exerts a braking torque via a compression spring when it is not electrically powered, so as to prevent uncontrolled rotation of the rotating part of the crane when it is in weathervane mode.

[0014] This solution, described in document EP2123592, thus provides a braking torque that directly corresponds to the pressure force of the compression spring. For the proper functioning of this disc brake, the compression stroke of the compression spring must be checked at regular intervals throughout the crane's operation on site; indeed, the more the disc brake is used, the more the brake disc wears down due to friction, and therefore its thickness decreases. Thus, over time and with wear, the compression spring loses its thrust force, therefore the braking torque decreases, and consequently the maximum possible speed for the rotating part increases in the event of uncontrolled rotation when it is set to weathervane mode. Another drawback is that the braking torque exerted by this disc brake is constant, which can prevent the rotating part from aligning itself with the wind at low wind speeds. Summary of the invention

[0015] The present aims to resolve in whole or in part the aforementioned disadvantages, by means of an additional braking device which, when the rotating part is set in weathervane mode, allows alignment of the rotating part in the direction of the wind for low, non-critical wind speeds, and braking of the rotation of the rotating part for higher, or even critical, wind speeds, which could cause it to tip into an uncontrolled rotation.

[0016] Another object of the invention is to propose an additional braking device which is not subject to mechanical wear, compared to the solution with the disc brake and the compression spring, and which is therefore easier to maintain and more robust.

[0017] To this end, the invention proposes a guidance system for controlling the orientation of a rotating part of a crane, this guidance system comprising at least: - a slewing geared motor comprising a slewing motor having a motor shaft, and a slewing reducer coupled to the motor shaft, the motor shaft being able to rotate in two directions of rotation which are a clockwise direction and a counterclockwise direction; - a main steering brake that can be deactivated to allow the rotating part to be set in weathervane mode; and - an additional braking device capable of being activated when the rotating part is put into weathervane mode to exert on the drive shaft a braking torque opposite to a steering torque exerted by the rotating part on the drive shaft.

[0018] This steering system is remarkable in that the additional braking device comprises: - a bidirectional hydraulic motor mechanically coupled to the drive shaft of the slewing motor to be able to apply the braking torque to the drive shaft in both directions of rotation, said bidirectional hydraulic motor comprising a first hydraulic orifice and a second hydraulic orifice such that the slewing torque in the clockwise direction, respectively in the counterclockwise direction, leads to a control pressure at the outlet of the first hydraulic orifice, respectively at the outlet of the second hydraulic orifice; and - a hydraulic circuit connected between the first hydraulic port and the second hydraulic port; in which the hydraulic circuit is configurable between: - an inactive configuration in which pressure is balanced between the first and second hydraulic ports, so that the additional braking device is deactivated and does not exert braking torque on the drive shaft; and - an active configuration in which a pressure regulation is established to control a pressure differential between the first hydraulic port and the second hydraulic port which generates the braking torque, so that the additional braking device is activated and exerts said braking torque on the drive shaft according to the pressure regulation.

[0019] Thus, it is proposed to use an additional braking device which is hydraulic and which includes a bidirectional hydraulic motor which can exert a braking torque in both directions of rotation when activated (hydraulic circuit in active configuration) to avoid or limit an uncontrolled rotation of said rotating part when turning into a weather vane, and which does not exert a braking torque when deactivated (hydraulic circuit in inactive configuration).

[0020] When the additional braking device is activated and the rotating part is pushed by the wind, the steering torque (which corresponds to the torque exerted by the rotating part on the drive shaft when this rotating part is in weathervane mode) is transmitted to the bidirectional hydraulic motor so as to have a control pressure (which results in overpressure) at one of the two hydraulic ports and therefore at the inlet of the hydraulic circuit. For a given steering torque, the additional braking device exerts a braking torque (which is opposite to the steering torque) by regulating the pressure to create a pressure differential that generates the braking torque.

[0021] The braking torque can be exerted when the steering torque (which corresponds to the torque exerted by the rotating part being pushed by the wind) exceeds a high torque threshold and / or remains below a low torque threshold; the steering torque itself being a function of the wind speed. Indeed, the higher the wind speed, the greater the thrust exerted by the wind on the rotating part, and therefore the greater the steering torque exerted by the rotating part on the drive shaft, and thus the greater the control pressure.

[0022] The lower torque threshold (or the associated minimum wind speed) and / or the upper torque threshold (or the associated maximum wind speed) is / are defined or adjusted by means of pressure regulation in the active configuration of the hydraulic circuit. Indeed, the stronger the wind, the greater the steering torque, and therefore the greater the steering torque transmitted to the bidirectional hydraulic motor, and thus the greater the control pressure on one of the two hydraulic ports (depending on the direction of rotation).

[0023] In a particular embodiment, the hydraulic circuit comprises: - a main loop connecting the first hydraulic port to the second hydraulic port; - a secondary loop connecting the first hydraulic port to the second hydraulic port, and on which a pressure regulation assembly is provided; in which said hydraulic circuit includes a main distributor disposed on the main loop and adjustable between: - an open position establishing a primary fluidic communication on the main loop, so that the hydraulic circuit is in an inactive configuration; and - a closed position cutting off the primary fluidic communication on the main loop and establishing a secondary fluidic communication on the secondary loop through the pressure regulation assembly, so that the hydraulic circuit is in an active configuration.

[0024] Thus, the pressure regulation assembly ensures pressure regulation to, where appropriate, control the pressure differential between the first hydraulic orifice and the second hydraulic orifice and thus generate the braking torque.

[0025] According to one possibility, the pressure regulation assembly includes, on the secondary loop, a leakage control device having a predefined and configurable low pressure threshold between: - a closed position, when the control pressure is above the low pressure threshold, in which the leak control device is closed; and - an open position, when the control pressure is below the low pressure threshold, in which the leak control device is open and allows leakage at a leak pressure that is equivalent to the control pressure.

[0026] The low pressure threshold is associated with a low torque threshold for the steering torque, and therefore with a minimum wind speed. In other words, the low pressure threshold is set according to the minimum wind speed below which the leak control device is required to be open in order to avoid exerting a braking torque.

[0027] This leakage control device allows pressure to escape without blocking the orientation of the drive shaft when the control pressure is below the low pressure threshold. Therefore, it prevents the rotation of the rotating part from being blocked below the low torque threshold of the slewing torque (or below a minimum wind speed), which is a function of this low pressure threshold. This ensures free orientation of the rotating part in the wind as long as the slewing torque is low (or as long as the wind speed is low, below the minimum wind speed), i.e., as long as the control pressure is below the low pressure threshold. Adjusting this low pressure threshold thus allows the minimum threshold speed below which the crane is free to align itself with the wind to be set.

[0028] According to another possibility, the pressure regulation assembly includes, on the secondary loop, a proportional pressure regulating valve set to a high pressure threshold and configurable between: - a closed position, when the control pressure is below the high pressure threshold, in which the proportional pressure regulating valve is closed; and - an open position, when the control pressure is above the high pressure threshold, in which the proportional pressure regulating valve is open and leaks at a regulating pressure that is proportional to and lower than the control pressure.

[0029] The high pressure threshold is associated with a high torque threshold for the steering torque, and therefore with a maximum wind speed. In other words, the high pressure threshold is set according to the maximum wind speed above which the proportional pressure regulating valve is to be opened to exert a braking torque proportional to the steering torque (or proportional to the wind speed).

[0030] This proportional pressure regulating valve is advantageous because, when the control pressure exceeds the upper pressure threshold (and therefore when the wind speed exceeds the maximum wind speed), the proportional pressure regulating valve regulates the pressure so that the pressure regulation assembly applies a braking torque that is proportional to the steering torque (and therefore to the pressure generated by the shunting of the oil flow passing through this proportional pressure regulating valve). Thus, this proportional pressure regulating valve prevents the rotating part from gaining too much speed and therefore limits the accumulation of kinetic energy which, if excessive, could cause the rotating part to spin again, leading to the phenomenon of unwanted autorotation.

[0031] Such a proportional pressure regulating valve is therefore advantageous for allowing or preventing a permanent slippage of the orientation at low speed, in order to permanently allow the rotating part to be positioned in the direction of the wind. Indeed, depending on the setting of the proportional pressure regulating valve, it allows, even with the bidirectional hydraulic motor engaged, for pressure to be released or not without blocking the orientation of the drive shaft.

[0032] In other words, the proportional pressure regulating valve plays a regulatory role to prevent the rotation of the rotating part from accelerating too quickly.

[0033] According to one feature, the leak control device and the proportional pressure control valve are arranged on parallel branches of the secondary loop.

[0034] According to another characteristic, the lower pressure threshold is equal to the upper pressure threshold.

[0035] Thus, the proportional pressure regulating valve takes over directly from the leakage regulating device when the control pressure increases and exceeds the low pressure threshold.

[0036] In this way, if the wind picks up but is not strong, then the control pressure, regardless of the direction of rotation, does not exceed the lower pressure threshold, and therefore the leakage control device fulfills its leakage role so that the rotating part follows the wind direction. If the wind force increases, the steering torque also increases, and therefore the control pressure increases and exceeds the lower pressure threshold and thus exceeds the upper pressure threshold of the proportional pressure control valve; and therefore this proportional pressure control valve comes into action by controlling the control pressure by managing the flow proportionally to the control pressure (the higher the control pressure, the higher the braking torque and therefore the more the rotating part is braked).

[0037] According to one variant, the lower pressure threshold is strictly lower than the upper pressure threshold.

[0038] In this variant, the proportional pressure regulating valve does not directly take over from the leakage regulating device when the control pressure increases and exceeds the low pressure threshold.

[0039] When the control pressure exceeds the lower pressure threshold but does not reach the upper pressure threshold, the leakage control device and the proportional pressure control valve are closed, and therefore the rotating part is locked in its position (and thus does not align itself with the wind) as long as the control pressure does not increase further (in other words, as long as the wind speed does not increase further). If the wind force increases and causes the steering torque to exceed the upper torque threshold, and therefore the control pressure to exceed the upper pressure threshold, then the proportional pressure control valve activates and acts as a regulator to prevent the rotation of the rotating part from accelerating too rapidly.

[0040] According to another possibility, the pressure regulation assembly includes, on the secondary loop, a control pressure limiter having a safety pressure threshold and configurable between: - a closed position, when the control pressure is below the safety pressure threshold, in which the control pressure limiter is closed; and - an open position, when the control pressure is above the safety pressure threshold, in which the control pressure limiter is open and leaks at a control pressure equivalent to the control pressure.

[0041] This control pressure limiter allows that, when the control pressure is too high (because the wind is too strong), then the control pressure limiter opens to release the rotating part and allow the boom to move in the direction of the wind without any other condition, in order to avoid damage and the risk of falling in the event of strong gusts of wind.

[0042] Advantageously, an energy dissipator, such as a heat exchanger, is placed on the secondary loop for the dissipation of energy generated by hydraulic shunting at least in the check valves and the control pressure limiter.

[0043] According to one feature, the leak control device and the control pressure limiter are arranged on parallel branches of the secondary loop.

[0044] Advantageously, the lower pressure threshold is strictly lower than the safety pressure threshold.

[0045] According to another feature, the proportional pressure regulating valve and the control pressure limiter are arranged on parallel branches of the secondary loop.

[0046] Advantageously, the upper pressure threshold is strictly lower than the safety pressure threshold.

[0047] Advantageously, the leak control device, the proportional pressure control valve and the control pressure limiter are arranged on parallel branches of the secondary loop.

[0048] In a particular embodiment, check valves are provided on the secondary pipeline to direct the control pressure in the pressure regulation assembly regardless of the direction of rotation of the motor shaft.

[0049] These check valves allow the oil flow to be directed in the pressure regulation assembly, regardless of the direction of rotation of the drive shaft, in other words regardless of the hydraulic port under pressure; the oil flowing from the hydraulic port under pressure to the other hydraulic port being directed through the pressure regulation assembly by means of the check valves.

[0050] In a particular embodiment, an energy sink, such as a heat exchanger, is in communication with the secondary loop for the dissipation of energy generated by hydraulic throttling, at least in the pressure regulation assembly.

[0051] Such an energy dissipator thus allows for the dissipation of the energy produced by braking (by a lamination effect of the hydraulic oil).

[0052] In a particular embodiment, the main distributor comprises a first input and a second input, and a first output and a second output, where communications are cut off between the first input and the first output and between the second input and second output in the open position, and where communications are established between the first input and the first output and between the second input and the second output in the closed position.

[0053] In a particular embodiment, the main loop comprises: - a first main inlet line connecting the first hydraulic port to the first inlet of the main distributor, - a second main inlet line connecting the second hydraulic port to the second inlet of the main distributor, - a first main outlet line connecting the first hydraulic port to the first outlet of the main distributor, and on which is placed one of the check valves, called the first valve, arranged to block circulation towards the first outlet of the main distributor, and - a second main outlet line connecting the second hydraulic port to the first outlet of the main distributor, and on which is placed one of the check valves, called the second valve, arranged to block the flow towards the first outlet of the main distributor.

[0054] According to one possibility, the secondary loop comprises: - an upstream line and a downstream line between which the pressure regulation assembly is placed; - a first secondary inlet line connecting the first hydraulic orifice to the upstream line, and on which is placed one of the check valves, called the third valve, arranged to block the flow towards the first hydraulic orifice; - a second secondary inlet line connecting the second hydraulic orifice to the upstream line, and on which is placed one of the check valves, called the fourth valve, arranged to block the flow towards the second hydraulic orifice.

[0055] According to another possibility, the leak control device is placed on a leak branch which is disposed between the upstream line and the downstream line.

[0056] According to one variant, the proportional pressure regulating valve is placed on a regulating branch between the upstream line and the downstream line.

[0057] According to another variant, the control pressure limiter is placed on a control branch which is disposed between the upstream line and the downstream line.

[0058] According to one characteristic, the secondary loop comprises: - a first secondary outlet line connecting the downstream line to the first outlet of the main distributor, between the first valve and the second valve; and - a second secondary output line connecting the downstream line to the second output of the main distributor.

[0059] According to another feature, the energy sink is placed on the first secondary output line or on the second secondary output line

[0060] In an advantageous embodiment, the main distributor has dual manual and electric control.

[0061] Thus, the manual control will make it possible to inhibit the action of the bidirectional hydraulic motor in the event that it is necessary to release the orientation of the rotating part, and the electric control will make it possible, when the crane is in service, to inhibit the action of the bidirectional hydraulic motor.

[0062] The invention also relates to a crane comprising a rotating part which is orientable around a vertical orientation axis, the rotation of the rotating part being controlled by an orientation system as described above. Brief description of the drawings

[0063] Other features and advantages of the present invention will become apparent from the following detailed description, along with several non-limiting examples of implementation, made with reference to the accompanying figures in which:

[0064] [Fig-1] is a schematic view of a crane equipped with a slewing system according to the invention, with a zoom on this orientation system;

[0065] [Fig.2] is a schematic view of a guidance system comprising a circuit hydraulic according to a first embodiment, in an inactive configuration;

[0066] [Fig.3] is a schematic view of the orientation system of [Fig.2], in a active configuration with a control pressure lower than the low leakage pressure threshold, this maximum leakage pressure threshold being equal to the high pressure threshold;

[0067] [Fig.4] is a schematic view of the orientation system of [Fig.2], in a active configuration with a control pressure higher than the low leak pressure threshold and the high pressure threshold, but also lower than the safety pressure threshold;

[0068] [Fig.5] is a schematic view of the orientation system of [Fig.2], in a active configuration with a control pressure higher than the safety pressure threshold;

[0069] [Fig.6] is a schematic view of the orientation system of [Fig.2], in a active configuration with a control pressure higher than the low leakage pressure threshold and lower than the high pressure threshold, this maximum leakage pressure threshold being strictly lower than the high pressure threshold;

[0070] [Fig.7] is a schematic view of the orientation system of [Fig.2], in a active configuration with a control pressure higher than the high pressure threshold, but also lower than the safety pressure threshold;

[0071] [Fig.8] is a schematic view of a steering system comprising a hydraulic circuit according to a second embodiment in an active configuration, with a control pressure below the safety pressure threshold;

[0072] [Fig.9] is a schematic view of a guidance system comprising a circuit hydraulic according to a third embodiment, in an inactive configuration.

[0073] [Detailed description of several embodiments of the invention]

[0074] With reference to [Fig. 1], a crane 8, here a tower crane, comprises a rotating part 9 which is orientable about a vertical orientation axis 90, as schematically represented by the double boom "91". This rotating part 9 is movable in rotation on the top 82 of a mast 80 (also called a tower) of vertical extension, where the mast 80 has a base 81 which rests on the ground.

[0075] This rotating part 9 comprises a pivot assembly 92 rotatably mounted on the top 82 of the mast 80 about the orientation axis 90, and a boom 93 mounted on the pivot assembly 92. A load distribution and lifting system 94 is mounted on the boom 93 to distribute and lift / lower a load along the boom 93.

[0076] The rotating part 9 may also include a counter boom 95 mounted on the pivot assembly 92, opposite the boom 93, and one or more ballasts 96 may be mounted on the counter boom 95. The rotating part 9 further includes a pilot's cabin 97, located on the pivot assembly 92 at the base of the boom 93. It is conceivable to have a boom support 98 or punch which is mounted vertically on the pivot assembly 92, to support the boom 93, and possibly the counter boom 95, for example by means of stays.

[0077] The rotating part 9 is pivotally mounted by means of an orientation system 1 provided on the pivot assembly 92, where this orientation system 1 includes an orientation ring 10 whose function is to pivotally link the pivot assembly 92 of the rotating part 9 to the top 82 of the mast 80.

[0078] This slewing ring 10 comprises two concentric rings 11, 12, with a fixed ring 11 connected to the top 82 of the mast 80 and with a movable ring 12 integral with the pivot assembly 92. Cylindrical bearings or rollers are mounted to roll between the two concentric rings 11, 12. The fixed ring 11 is in the form of a toothed ring.

[0079] The orientation system 1 further includes, to ensure the rotation of the rotating part 9 thus kinematically connected to the mast 80, at least one orientation geared motor 13 mounted on this rotating part 9.

[0080] This slewing geared motor 13 comprises a slewing motor 14 having a motor shaft 15 (schematically shown in Figures 2 to 7), and a slewing reducer 16 coupled to the motor shaft and driving in rotation a vertical axis pinion 17 which is engaging with the teeth provided on the fixed ring 11 of the slewing ring 10. The slewing system 1 includes a variator (not shown) connected to the slewing motor to adjust its speed and torque.

[0081] Depending on the mechanical power to be transmitted to rotate the rotating part 9, it is possible to provide one or more orientation geared motors on the rotating part 9. In the example illustrated in [Fig.1], another orientation geared motor 13' is provided on the rotating part 9.

[0082] The slewing system 1 includes a main slewing brake 18, which is formed by an internal brake of the slewing geared motor 13, or of one of the slewing geared motors 13, 13'. This main slewing brake 18 is controlled by an electromagnet. When the slewing geared motor 13 is stopped, the electromagnet's coil is not electrically energized, and a braking torque is exerted to prevent the rotating part 9 from rotating. Conversely, when the electromagnet is electrically energized, no braking torque is exerted by this main slewing brake 18.

[0083] Thus, this main slewing brake 18 is designed to be deactivated when the rotating part 9 is in weathervane mode, that is, when the crane 8 is "out of service," outside of its working periods. This weathervane mode means that the slewing geared motor 18 is disengaged to allow the rotating part 9 to orient itself freely according to the wind direction. In operation, to allow the crane 8 to weathervane, the crane operator deactivates the main slewing brake 18 when leaving their workstation.

[0084] Crane 8 also includes a connected control / command unit (not shown): - to the orientation system 1, and more specifically to the variator of the or each orientation geared motor 13, 13', in order to control the orientation of the rotating part 9; - to the main steering brake 18 in order to actuate this brake to block or release the steering of the rotating part 9.

[0085] Crane 8 is thus configurable between: - a service configuration in which the rotating part 9 can be steered in rotation on the mast 80 around the orientation axis 90 by piloting the orientation system 1 using the control / command unit; and - an out-of-service configuration in which the rotating part 9 is released to rotate on the mast 80 along the orientation axis 90 in order to be able to orient itself in the direction of the wind, the main orientation brake 18 being deactivated and the orientation system 1 being disengaged in the out-of-service configuration.

[0086] The slewing system 1 includes an additional braking device 2 that can be activated when the rotating part 9 is put into weathervane mode to exert a braking torque on the drive shaft 15 of the slewing geared motor 13, in order to slow down or at least brake the rotation of the rotating part 9 during weathervane mode, so as to prevent its uncontrolled rotation. When the crane 8 is in the service configuration, this additional braking device 2 is not activated, so as not to exert any braking torque.

[0087] When the crane 8 is in the out-of-service configuration, the rotating part 9 is free to rotate under the effect of the wind, and it therefore experiences a wind thrust which results in a steering torque CO exerted by the rotating part 9 on the drive shaft 13. The braking torque exerted by the additional braking device 2 is therefore opposed to the steering torque CO, regardless of the direction of the steering torque CO (in other words the direction of rotation of the rotating part 9).

[0088] This additional braking device 2 is a hydraulic device, which includes a bidirectional hydraulic motor 20 mechanically coupled to the drive shaft 15 of the slewing motor 14 so as to be able to apply the braking torque to the drive shaft 15 in both directions of rotation. Thus, the slewing torque CO is transmitted by the drive shaft 13 to the bidirectional hydraulic motor 20 which, in response (as described below), exerts the braking torque opposite to the slewing torque CO.

[0089] This additional hydraulic motor 20 comprises a first hydraulic port 21 and a second hydraulic port 22, such that the clockwise steering torque CO leads to a control pressure P (in other words, an overpressure) at the outlet of the first hydraulic port 21; and - in the counterclockwise direction, leads to a control pressure P (in other words an overpressure) at the outlet of the second hydraulic orifice 22.

[0090] This additional braking device 2 comprises a hydraulic circuit 3 connected between the first hydraulic port 21 and the second hydraulic port 22, which is configurable between: - an inactive configuration in which pressure is balanced between the first hydraulic port 21 and the second hydraulic port 22, so that the bidirectional hydraulic motor 20 of the additional braking device 2 is inactive and does not exert braking torque on the drive shaft 15; and - an active configuration in which a pressure regulation is established to control a pressure differential between the first hydraulic port 21 and the second hydraulic port 22 which generates the braking torque, so that the bidirectional hydraulic motor 20 of the additional braking device 2 is activated and exerts the braking torque on the motor shaft 15, this braking torque being able to be modulated through the pressure regulation.

[0091] In the first embodiment of Figures 2 to 7, the second embodiment of [Fig. 8] and the third embodiment of [Fig. 9], the hydraulic circuit 3 comprises: - a main loop 31 connecting the first hydraulic orifice 21 to the second hydraulic orifice 22; - a secondary loop 32 connecting the first hydraulic port 21 to the second hydraulic port 22, and on which a pressure regulation assembly 4 is provided.

[0092] The hydraulic circuit 3 includes a main distributor 6 arranged on the main loop 30 and adjustable between: - an open position (on [Fig.2]) establishing a main fluidic communication on the main loop 31, so that the hydraulic circuit 3 is in an inactive configuration; and - a closed position (on Figures 3 to 9) cutting off the main fluidic communication on the main loop 31 and establishing a secondary fluidic communication on the secondary loop 32 through the pressure regulation assembly 4, so that the hydraulic circuit 3 is in active configuration.

[0093] The hydraulic circuit 3 includes check valves 51, 52, 53, 54, 55, 56 on the secondary loop 32 to direct the control pressure P in the pressure regulating assembly 4 regardless of the direction of rotation of the motor shaft 15.

[0094] In the first embodiment of Figures 2 to 7, the pressure control assembly 4 includes, on the secondary loop 32, a leak control device 41 having a predefined and configurable low pressure threshold PI between: - a closed position, when the control pressure P is greater than the low pressure threshold PI, in which the leak control device 41 is closed; and - an open position, when the control pressure P is less than the low pressure threshold PI, in which the leak control device 41 is open and allows leakage at a leak pressure that is equivalent to the control pressure P.

[0095] This low pressure threshold PI is associated with a low torque threshold Cl for the steering torque CO, and therefore with a minimum wind speed VI for the wind speed V. In other words, the low pressure threshold PI is set according to the minimum wind speed V1 below which (or according to the low torque threshold Cl below which) the leak control device 41 is to be open so as not to exert braking torque.

[0096] In other words, when the control pressure P is less than the low pressure threshold PI (i.e., when the wind speed V is less than the minimum wind speed VI or when the steering torque CO is less than the low torque threshold Cl), the leakage control device 41 is open, and thus the control pressure P leaks through this leak control device 41, thus balancing the pressures between the first hydraulic orifice 21 and the second hydraulic orifice 22, and therefore the braking torque is zero.

[0097] In the first embodiment of Figures 2 to 7, the pressure control assembly 4 comprises, on the secondary loop, a proportional pressure control valve 42 set at a high pressure threshold P2 and configurable between: - a closed position, when the control pressure P is lower than the high pressure threshold P2, in which the proportional pressure control valve 42 is closed; and - an open position, when the control pressure P is greater than the high pressure threshold P2, in which the proportional pressure regulating valve 42 is open and leaks at a regulating pressure that is proportional to and less than the control pressure P.

[0098] This high pressure threshold P2 is associated with a high torque threshold C2 for the steering torque CO, and therefore with a maximum wind speed V2 for the wind speed V. In other words, the high pressure threshold P2 is set according to the maximum wind speed V2 above which (or according to the high torque threshold C2 above which) the proportional pressure regulating valve 42 is to be opened to exert the braking torque.

[0099] In other words, when the control pressure P is greater than the upper pressure threshold P2 (i.e. when the wind speed V is greater than the maximum wind speed V2 or when the steering torque CO is greater than the upper torque threshold C2), the proportional pressure regulating valve 42 is open, and thus the control pressure P leaks through this proportional pressure regulating valve 42, being regulated to a regulating pressure which is proportional to and less than the control pressure P, thus establishing a pressure differential between the first hydraulic port 21 and the second hydraulic port 22, and therefore the braking torque is exerted on the drive shaft 13 and thus on the rotating part 9.

[0100] In the first embodiment of Figures 2 to 7, the pressure regulation assembly 4 comprises, on the secondary loop 32, a control pressure limiter 43 having a safety pressure threshold P3 and configurable between: - a closed position, when the control pressure P is below the safety pressure threshold P3, in which the control pressure limiter 43 is closed; and - an open position, when the control pressure P is greater than the safety pressure threshold P3, in which the control pressure limiter 43 is open and leaks at a control pressure equivalent to the control pressure P.

[0101] This safety pressure threshold P3 is associated with a safety torque threshold C3 for the orientation torque CO, and therefore with a safety wind speed V3 for the wind speed V. In other words, the safety pressure threshold P3 is set according to the safety wind speed V3 above which (or according to the safety torque threshold C3 above which) the control pressure limiter 43 is to be opened so as not to exert braking torque and to allow the rotating part to run.

[0102] In other words, when the control pressure P is greater than the safety pressure threshold P3 (i.e. when the wind speed V is greater than the safety wind speed V3 or when the steering torque CO is greater than the safety torque threshold C3), the control pressure limiter 43 is open, and thus the control pressure P leaks through this control pressure limiter 43, thus balancing the pressures between the first hydraulic port 21 and the second hydraulic port 22, and therefore the braking torque is zero.

[0103] In the first embodiment of Figures 2 to 7, the leak control device 41, the proportional pressure control valve 42 and the control pressure limiter 43 are arranged on parallel branches of the secondary loop 32.

[0104] More specifically, the main distributor 6 is a 4 / 2 distributor, for example with dual manual and electric control. This main distributor 6 comprises a first inlet 61 and a second inlet 62, and a first outlet 63 and a second outlet 64, and where: - communications are cut between the first input 61 and the first output 63 and between the second input 62 and the second output 64 in the open position, and - communications are established between the first input 61 and the first output 63 and between the second input 62 and the second output 64 in the closed position.

[0105] In the first embodiment of Figures 2 to 7 and in the second embodiment of [Fig. 8], the main loop 31 comprises: - a first main inlet line 311 connecting the first hydraulic port 21 to the first inlet 61 of the main distributor 6, - a second main inlet line 312 connecting the second hydraulic port 22 to the second inlet 62 of the main distributor 6, - a first main outlet line 313 connecting the first hydraulic port 21 to the first outlet 63 of the main distributor 6, and on which is placed one of the check valves, called the first check valve 51, arranged to block circulation towards the first outlet 63 of the main distributor 6, and - a second main outlet line 314 connecting the second hydraulic port 22 to the first outlet 63 of the main distributor 6, and on which one of the non-return valves, called second valve 52, arranged to block the flow towards the first outlet 63 of the main distributor 6.

[0106] In the first embodiment of Figures 2 to 7 and in the second embodiment of [Fig. 8], the secondary loop 32 comprises: - an upstream line 321 and a downstream line 322 between which is placed the pressure regulation assembly 4; - a first secondary inlet line 323 connecting the first hydraulic orifice 21 to the upstream line 321, and on which is placed one of the non-return valves, called third valve 53, arranged to block circulation towards the first hydraulic orifice 21; - a second secondary inlet line 324 connecting the second hydraulic orifice 22 to the upstream line 22, and on which is placed one of the check valves, called the fourth valve 54, arranged to block circulation towards the second hydraulic orifice 22.

[0107] In the first embodiment of Figures 2 to 7, the leak control device 41 is placed on a leak branch 325 which is disposed between the upstream line 321 and the downstream line 322, and between the two check valves 53, 54.

[0108] The proportional pressure regulating valve 42 is placed on a regulating branch 326 which is disposed between the upstream line 321 and the downstream line 322, and between the two check valves 53, 54.

[0109] The control pressure limiter 43 is placed on a control branch 327 which is disposed between the upstream line 321 and the downstream line 322, and between the two check valves 53, 54.

[0110] In the first embodiment of Figures 2 to 7 and in the second embodiment of [Fig. 8], the secondary loop 32 comprises: - a first secondary outlet line 328 connecting the downstream line 322 to the first outlet 63 of the main distributor 6, between the first valve 51 and the second valve 52; and - a second secondary output line 329 connecting the downstream line to the second output 64 of the main distributor 6.

[0111] An energy sink 71 is placed on the secondary loop 32, and more specifically on the first secondary output line 328 or on the second secondary output line 329. This energy sink 71, such as a heat exchanger, is therefore in communication with the secondary loop 32 for the dissipation of energy generated by hydraulic shunting in the pressure regulation assembly 4.

[0112] A hydraulic accumulator 72 is placed on the secondary loop 32, and more precisely on the upstream line 321.

[0113] In a first use of the hydraulic circuit 3 of the first embodiment, the lower pressure threshold PI is equal to the upper pressure threshold P2, for example, a value of 10 bar, and the safety pressure threshold P3 is greater than both the lower pressure threshold PI and the upper pressure threshold P2, for example, a value of 300 bar. The values ​​of these thresholds PI, P2, P3 are established as a function of the torque thresholds Cl, C2, C3 for the orientation torque CO, and therefore of the thresholds VI, V2, V3 for the wind speed V. Thus, in this first use, we have P1=P2 <P3, C1=C2<C3 et donc V1=V2<V3.

[0114] In this first use, the crane 8 being in its out-of-service configuration (therefore the rotating part 9 is set to weather vane), the operation of the hydraulic circuit 3, and therefore of the additional braking device 2, is described below with reference to Figures 3 to 5.

[0115] With reference to [Fig. 3], when the wind is calm or weak (i.e., the wind speed V is less than the minimum wind speed V1, which, as a reminder, is equal to the maximum wind speed V2) and therefore the steering torque CO exerted by the rotating part 9 is zero or less than the low torque threshold Cl, which is equal to the high torque threshold C2, then the control pressure P is less than the low pressure threshold PI (and therefore also the high pressure threshold P2) - in summary V <V1=V2, CO<C1=C2 et P<P1=P2 -, alors le dispositif de régulation de fuite 41 est ouvert, la valve de régulation de pression proportionnelle 42 est fermée et le limiteur de pression de contrôle 43 est fermé. Ainsi, la pression de commande P fuit au travers du dispositif de régulation de fuite 41 et donc la partie tournante 9 s’aligne dans le vent sans être freiné par le dispositif de freinage additionnel 2.

[0116] With reference to [Fig. 4], when the wind force increases and therefore the wind speed V becomes greater than the minimum wind speed V1 (which, as a reminder, is equal to the maximum wind speed V2) without reaching the safety wind speed V3, and therefore the steering torque CO exerted by the rotating part 9 exceeds the lower torque threshold Cl, which is equal to the upper torque threshold C2 without reaching the safety torque threshold C3, then the control pressure P exceeds the lower pressure threshold PI (and therefore also the upper pressure threshold P2) - in summary V1=V2 <V<V3, C1=C2<CO<C3 et P1=P2<P<P3 -, alors le dispositif de régulation de fuite 41 est fermé, la valve de régulation de pression proportionnelle 42 est ouverte et le limiteur de pression de contrôle 43 est fermé.Thus, the proportional pressure regulating valve 42 comes into action by controlling the leakage pressure by managing the flow proportionally to the control pressure P, so that the more the control pressure P increases (and therefore the more the wind speed V increases) the more the braking torque exerted by the additional braking device 2 increases.

[0117] With reference to [Fig. 5], when the wind force becomes too great and therefore the wind speed V exceeds the safety wind speed V3, and thus the steering torque CO exceeds the safety torque threshold C3, then the control pressure P exceeds the safety pressure threshold P3 – in summary, V>V3, CO>C3 and P>P3 – then the control pressure limiter 43 opens. Thus, the control pressure P leaks through the control pressure limiter 43 and therefore the rotating part 9 aligns itself with the wind without being slowed by the additional braking device 2.

[0118] This scenario is considered when a gust of wind tends to push the rotating part 9 very strongly, with a wind speed exceeding the safety wind speed V3 (for example, when this rotating part 9 is perpendicular to the wind direction), and in this case, it is necessary to allow the rotating part 9 to align itself with the wind without braking torque. In this situation of [Fig. 5], the proportional pressure regulating valve 42 is not able to evacuate all of the hydraulic flow generated by this sudden acceleration, and it is therefore at this moment that the control pressure limiter 43 acts as a safety valve by reducing the circuit pressure to a level manageable by the proportional pressure regulating valve 42. In other words, once the gust has passed, the control pressure P drops back down and falls below the safety pressure threshold P3, returning to the situation of [Fig. 4].

[0119] In a second use of the hydraulic circuit 3 of the first embodiment, the low pressure threshold PI is set very low (for example, to a value of 1 bar so that it is almost constantly closed), the high pressure threshold P2 is strictly higher than the low pressure threshold PI, for example, to a value of 50 bar, and the safety pressure threshold P3 is strictly higher than the high pressure threshold P2, for example, to a value of 55 bar. The values ​​of these thresholds PI, P2, P3 are established as a function of the torque thresholds Cl, C2, C3 for the orientation torque CO, and therefore of the thresholds VI, V2, V3 for the wind speed V. Thus, in this second use, we have P1 <p2<p3, c1<c2<c3 et donc v1<v2<v3.

[0120] In this second use, the crane 8 being in its out-of-service configuration (therefore the rotating part 9 is set to weather vane), the operation of the hydraulic circuit 3, and therefore of the additional braking device 2, is described below with reference to Figures 6 and 7.

[0121] With reference to [Fig. 6], the wind rises; it is not strong, but it is sufficient that the wind speed V exceeds the minimum wind speed VI, without, however, reaching the maximum wind speed V2. Therefore, the rotating part 9 begins to rotate gently, and the steering torque CO almost immediately exceeds the lower torque threshold Cl without reaching the upper torque threshold C2. Then the control pressure P exceeds the lower pressure threshold PI, without yet reaching the upper pressure threshold P2 - in summary V 1 <v<v2<v3, c1<co<c2<c3 et p1<p<p2<p3 ainsi, dès que la partie tournante 9 commence à tourner, le dispositif de régulation fuite 41 est fermé, valve pression proportionnelle 42 fermée limiteur contrôle 43 fermé. donc fortement freinée, au point d’être arrêtée dans sa rotation, car commande p ne peut pas circuler librement cause fermeture ces trois moyens 41, 42, du fait tarage bas 41. si vent continue d’augmenter, il exerce un effort sur donc augmente, mais tant n’atteint seuil haut p2 (autrement dit vitesse v dépasse maximale v2), alors restera figée position, jusqu’à ce p2.

[0122] With reference to [Fig. 7], when the wind force increases and therefore the wind speed V becomes greater than the maximum wind speed V2, without reaching the safety wind speed V3, and therefore the steering torque CO exceeds the upper torque threshold C2 without reaching the safety torque threshold C3, then the control pressure P exceeds the upper pressure threshold P2 without reaching the safety pressure threshold P3 - in summary V1 <v2<v<v3, c1<c2<co<c3 et p1<p2<p<p3 -, alors le dispositif de régulation fuite 41 est fermé, la valve pression proportionnelle 42 ouverte limiteur contrôle 43 fermé. ainsi, entre en action pour exercer couple freinage (comme décrit précédemment référence à [fig.4]).

[0123] If the wind force becomes too great and therefore the wind speed V becomes greater than the safety wind speed V3, then the control pressure limiter 43 opens (as described previously with reference to [Fig.5]).

[0124] Thus, in this second use, the position of the rotating part 9, as left by the crane operator when setting it to weathervane mode, will remain the same until a certain wind speed is reached, in other words, until the wind speed V exceeds the maximum wind speed V2. The additional braking device 2 thus makes it possible to lock the rotating part 9 for a light wind (below the maximum wind speed V2), and to allow the rotating part 9 to turn into the wind from a predefined wind level (above the maximum wind speed V2).

[0125] In the second embodiment of [Fig.8], the pressure regulation assembly 4 includes, on the secondary loop 32, a flow control valve 44 to reduce the pressure.

[0126] In the second embodiment of [Fig.8], the pressure regulation assembly 4 includes, on the secondary loop 32, a control pressure limiter 43 as described previously.

[0127] In the second embodiment of [Fig.8], the flow control valve 44 and the control pressure limiter 43 are arranged on parallel branches of the secondary loop 32.

[0128] The hydraulic circuits 3 of the first embodiment of Figures 2 to 7 and of the second embodiment of [Fig. 8] are identical, with the same main and secondary loops 31, 32, the same lines 311, 312, 313, 314, 321, 322, 323, 324, the same check valves 51, 52, 53, 54, the same energy sink 71 and the same hydraulic accumulator 72. The difference between the two circuits 3 lies in the fact that the leakage control device 41 and the proportional pressure control valve 42 are replaced by the flow control valve 44.

[0129] In the second embodiment of [Fig.8], the flow control valve 44 is placed on a flow control branch 330 which is arranged between the upstream line 321 and the downstream line 322, in parallel with the control branch 327 on which the control pressure limiter 43 is arranged.

[0130] In operation, in the out-of-service configuration of the crane 8, as long as the wind speed V is less than the safety wind speed V3, and therefore the slewing torque CO exerted by the rotating part 9 is less than the safety torque threshold C3, then the flow control valve 44 allows the rotating part 9 to be braked, according to its setting.

[0131] In the hydraulic circuit 3 of the third embodiment, the pressure regulation assembly 4 comprises, on the secondary loop 32, a first regulation sub-assembly 411 and a second regulation sub-assembly 412.

[0132] The first control sub-assembly 411 comprises in parallel a first flow control valve 441, a first control pressure limiter 431 and a first check valve 55. The second control sub-assembly 412 comprises in parallel a second flow control valve 442, a second control pressure limiter 432 and a second check valve 56. The first control pressure limiter 431 and the second control pressure limiter 432 each have the same safety pressure threshold P3.

[0133] In the third embodiment of [Fig.9], the main loop 31 comprises: - a first main inlet line 311 connecting the first hydraulic port 21 to the first inlet 61 of the main distributor 6, - a second main inlet line 312 connecting the second hydraulic port 22 to the second inlet 62 of the main distributor 6, - a first main outlet line 333 connecting the first hydraulic port 21 to the first outlet 63 of the main distributor 6, and on which is placed the first regulating sub-assembly 411, the first check valve 55 being arranged to block circulation towards the first outlet 63 of the main distributor 6, and - a second main outlet line 334 connecting the second hydraulic port 22 to the second outlet 64 of the main distributor 6, and on which is placed the second regulating sub-assembly 412, the second check valve 56 being arranged to block circulation towards the second outlet 64 of the main distributor 6.

[0134] The secondary loop 32 includes the parallel branches of the control sub-assemblies 411, 412, on which are placed the flow control valves 441, 442, the control pressure limiters 431, 432 and the check valves 55, 56.

[0135] A power sink 71 is placed on the secondary loop 32, and more specifically on a dissipation line 381 which connects the first output 63 of the main distributor 6 to the second output 64 of the main distributor 6.

[0136] In this third embodiment of [Fig.9], with the crane 8 in its out-of-service configuration (so the rotating part 9 is set to weathervane), the operation of the hydraulic circuit 3, and therefore of the additional braking device 2, is described below.

[0137] When the drive shaft 15 rotates clockwise, and as long as the wind speed V is less than the safety wind speed V3, and therefore the steering torque CO exerted by the rotating part 9 is less than the safety torque threshold C3, then the control pressure P is at the outlet of the first hydraulic port 21 and this control pressure P passes through the first control sub-assembly 411 so that the first flow control valve 441 allows the rotating part 9 to be braked, according to its setting.

[0138] When the drive shaft 15 rotates in the counterclockwise direction, and as long as the wind speed V is less than the safety wind speed V3, and therefore the steering torque CO exerted by the rotating part 9 is less than the safety torque threshold C3, then the control pressure P is at the outlet of the second hydraulic port 22 and this control pressure P passes through the second control sub-assembly 412 so that the second flow control valve 442 allows the rotating part 9 to be braked, according to its setting.

[0139] If the wind speed V exceeds the safety wind speed V3, then the first control pressure limiter 431 or the second control pressure limiter 432 opens, depending on the direction of rotation of the drive shaft 15, to allow the rotating part 9 to rotate freely.

[0140] Alternatively, the first flow control valve 441 can be replaced by a first leakage control device and a first proportional pressure control valve in parallel, and the second flow control valve 442 can be replaced by a second leakage control device and a second proportional pressure control valve in parallel. The operation will then be similar to that described for the first embodiment.

Claims

Demands

1. A slewing system (1) for controlling the orientation of a rotating part (9) of a crane, said slewing system (1) comprising at least: - a slewing geared motor (13) comprising a slewing motor (14) having a drive shaft (15), and a slewing gearbox (16) coupled to the drive shaft (15), the drive shaft (15) being able to rotate in two directions of rotation, which are clockwise and counterclockwise; - a main slewing brake (18) capable of being deactivated for weathervaning of the rotating part (9); and - an additional braking device (2); wherein: - in a service configuration, the slewing geared motor (13) is configured to control the rotation of the rotating part (9) and the additional braking device (2) is deactivated so as not to exert braking torque on the drive shaft;and - in an out-of-service configuration, the slewing gear motor (13) is disengaged and the main slewing brake (18) is deactivated for a weathervane of the rotating part (9) in order to orient itself freely according to the direction of the wind, and the additional braking device (2) is able to be activated during said weathervane of the rotating part (9) to exert on the motor shaft a braking torque opposite to a slewing torque (CO) exerted by the rotating part (9) on the motor shaft (15);said steering system (1) being characterized in that the additional braking device comprises: - a bidirectional hydraulic motor (20) mechanically coupled to the drive shaft (15) of the steering motor (14) in order to apply the braking torque to the drive shaft (15) in both directions of rotation, said bidirectional hydraulic motor (20) comprising a first hydraulic orifice (21) and a second hydraulic orifice (22) such that the steering torque (CO) in the clockwise direction, respectively in the counterclockwise direction, leads to a control pressure (P) at the outlet of the first hydraulic orifice (21), respectively at the outlet of the second hydraulic orifice (22); and; - a hydraulic circuit (3) connected between the first hydraulic port (21) and the second hydraulic port (22); in which the hydraulic circuit (3) is configurable between: - an inactive configuration in which pressure balancing is established between the first hydraulic port (21) and the second hydraulic port (22), so that the additional braking device (2) is inactivated and does not exert braking torque on the drive shaft (15); and - an active configuration in which pressure regulation is established to control a pressure differential between the first hydraulic port (21) and the second hydraulic port (22) which generates the braking torque, so that the additional braking device (2) is activated and exerts said braking torque on the drive shaft (15) according to the pressure regulation.

2. A steering system (1) according to claim 1, wherein the hydraulic circuit (3) comprises: - a main loop (31) connecting the first hydraulic port (21) to the second hydraulic port (22); - a secondary loop (32) connecting the first hydraulic port (21) to the second hydraulic port (22), and on which a pressure regulating assembly (4) is provided; wherein said hydraulic circuit (3) comprises a main distributor (6) disposed on the main loop (31) and adjustable between: - an open position establishing a main fluidic communication on the main loop (31), so that the hydraulic circuit is in an inactive configuration;and - a closed position cutting off the main fluidic communication on the main loop (31) and establishing a secondary fluidic communication on the secondary loop (32) through the pressure regulation assembly (4), so that the hydraulic circuit is in active configuration.;

3. A guidance system (1) according to claim 2, wherein the pressure control assembly (4) comprises, on the secondary loop, a leak control device (41) having a predefined and configurable low pressure threshold (PI) between: - a closed position, when the control pressure (P) is greater than the low pressure threshold (PI), in which the leak control device (41) is closed; and - an open position, when the control pressure (P) is below the low pressure threshold (PI), in which the leak control device (41) is open and allows leakage at a leak pressure that is equivalent to the control pressure (P).

4. A guidance system (1) according to claim 2 or 3, wherein the pressure control assembly (4) comprises, on the secondary loop (32), a proportional pressure control valve (42) set at a high pressure threshold (P2) and configurable between: - a closed position, when the control pressure (P) is less than the high pressure threshold (P2), in which the proportional pressure control valve (42) is closed; and - an open position, when the control pressure (P) is greater than the high pressure threshold (P2), in which the proportional pressure control valve (42) is open and leaks at a control pressure that is proportional to and less than the control pressure (P).

5. Guidance system (1) according to claims 3 and 4, wherein the leak control device (41) and the proportional pressure control valve (42) are arranged on parallel branches (325, 326) of the secondary loop (32).

6. Guidance system (1) according to claim 5, wherein the low pressure threshold (PI) is equal to the high pressure threshold (P2).

7. Guidance system (1) according to claim 5, wherein the lower pressure threshold (PI) is strictly less than the upper pressure threshold (P2).

8. A guidance system (1) according to any one of claims 2 to 7, wherein the pressure regulation assembly (4) comprises, on the secondary loop (32), a control pressure limiter (43; 431; 432) having a safety pressure threshold (P3) and configurable between: - a closed position, when the control pressure (P) is less than the safety pressure threshold (P3), in which the control pressure limiter (43; 431; 432) is closed; and - an open position, when the control pressure (P) is greater than the safety pressure threshold (P3), in which the control pressure limiter (43; 431; 432) is open and leaks at a control pressure equivalent to the control pressure (P).

9. Guidance system (1) according to claims 3 and 8, wherein the leak control device (41) and the control pressure limiter (43) are arranged on parallel branches (325, 327) of the secondary loop (32).

10. Guidance system (1) according to claim 9, wherein the low pressure threshold (PI) is strictly less than the safety pressure threshold (P3).

11. Guidance system (1) according to claims 4 and 8, wherein the proportional pressure regulating valve (42) and the control pressure limiter (43) are arranged on parallel branches (326, 327) of the secondary loop (32).

12. Guidance system (1) according to claim 11, wherein the high pressure threshold (P2) is strictly lower than the safety pressure threshold (P3).

13. Guidance system (1) according to claims 3, 4 and 8, wherein the leak control device (41), the proportional pressure control valve (42) and the control pressure limiter (43) are arranged on parallel branches (325, 326, 327) of the secondary loop (32).

14. Guidance system (1) according to any one of claims 2 to 13, wherein the pressure control assembly (4) includes, on the secondary loop, a flow control valve (44; 441; 442).

15. Guidance system (1) according to claims 8 and 14, wherein the flow control valve (44; 441; 442) and the control pressure limiter (43; 431; 432) are arranged on parallel branches of the secondary loop (32).

16. Guidance system (1) according to any one of claims 2 to 15, wherein check valves (51, 52, 53, 54; 55, 56) are provided on the secondary loop (32) to orient the control pressure (P) in the pressure regulating assembly (4) regardless of the direction of rotation of the drive shaft (15).

17. Guidance system (1) according to any one of claims 2 to 16, wherein an energy dissipator (71), such as a heat exchanger, is in communication with the secondary loop (32) for the dissipation of energy generated by hydraulic rolling at least in the pressure regulation assembly (4).

18. A guidance system (1) according to any one of claims 2 to 17, wherein the main distributor (6) comprises a first inlet (61) and a second inlet (62), and a first outlet (63) and a second outlet (64), wherein communications are cut off between the first inlet (61) and the first outlet (63) and between the second inlet (62) and the second outlet (64) in the open position, and wherein communications are established between the first inlet (61) and the first outlet (63) and between the second inlet (62) and the second outlet (64) in the closed position.

19. A guidance system (1) according to claims 16 and 18, wherein the main loop (32) comprises: - a first main inlet line (311) connecting the first hydraulic port (21) to the first inlet (61) of the main distributor (6), - a second main inlet line (312) connecting the second hydraulic port (22) to the second inlet (62) of the main distributor (6), - a first main outlet line (313) connecting the first hydraulic port (21) to the first outlet (63) of the main distributor (6), and on which is placed one of the check valves, called the first valve (51), arranged to block circulation towards the first outlet (63) of the main distributor (6), and - a second main outlet line (314;334) connecting the second hydraulic orifice (22) to the first outlet (63) of the main distributor (6), and on which is placed one of the check valves, called the second valve (52), arranged to block the flow towards the first outlet (63) of the main distributor (6).;

20. A guidance system (1) according to claim 19, wherein the secondary loop (32) comprises: - an upstream line (321) and a downstream line (322) between which the pressure regulating assembly (4) is placed; - a first secondary inlet line (323) connecting the first hydraulic orifice (21) to the upstream line (321), and on which one of the check valves, called the third valve (53), is placed, arranged to block circulation towards the first hydraulic orifice (21); - a second secondary inlet line (324) connecting the second hydraulic orifice (22) to the upstream line (321), and on which one of the check valves, called the third valve (53), is placed non-return valves, called the fourth valve (54), arranged to block circulation towards the second hydraulic orifice (22).

21. Guidance system (1) according to claims 3 and 20, wherein the leak control device (41) is placed on a leak branch (325) which is disposed between the upstream line (321) and the downstream line (322).

22. Guidance system (1) according to claims 4 and 20, wherein the proportional pressure regulating valve (42) is placed on a regulating branch (326) between the upstream line (321) and the downstream line (322).

23. Guidance system (1) according to claims 8 and 20, wherein the control pressure limiter (43) is placed on a control branch (327) which is disposed between the upstream line (321) and the downstream line (322).

24. Guidance system (1) according to any one of claims 20 to 23, wherein the secondary loop (32) comprises: - a first secondary output line (328) connecting the downstream line (322) to the first outlet (63) of the main distributor (6), between the first valve (51) and the second valve (52); and - a second secondary output line (329) connecting the downstream line (322) to the second outlet (64) of the main distributor (6).

25. Orientation system (1) according to claims 17 and 24, wherein the energy dissipator (71) is placed on the first secondary output line (328) or on the second secondary output line (329).

26. Guidance system (1) according to any one of claims 2 to 25, wherein the main distributor (6) is dual manual and electric control.

27. ​​Crane (8) comprising a rotating part (9) which is orientable about a vertical orientation axis (90), and comprising a slewing system (9) according to any one of the preceding claims, wherein the rotation of the rotating part (9) is controlled by said slewing system (9).