Slewing system for a crane comprising an additional hydraulic braking device

Abstract

Slewing system (1) for controlling the slewing of a rotating part (9) of a crane, said slewing system (1) comprising at least: - a slewing gear motor (13) comprising a slewing motor (14) having a drive shaft, and a slewing reduction gear (16) coupled to the drive shaft (15), the drive shaft (15) being able to rotate in two directions of rotation which are a clockwise direction and a counterclockwise direction; - a main slewing brake (18) able to be deactivated in order to allow the rotating part (9) to rotate freely according to the wind; and - an additional braking device (2) able to be activated when the rotating part is allowed to rotate freely in order to exert, on the drive shaft, a braking torque that is the opposite to a slewing torque exerted by the rotating part (9) on the drive shaft (15), wherein the additional braking device is a hydraulic device.

Description

[0001] DESCRIPTION

[0002] TITLE: Slewing system for a crane including an additional hydraulic braking device

[0003] [Technical field]

[0004] The invention relates to a steering system for controlling a steering of a rotating part of a crane, as well as to a crane comprising a rotating part controlled in steering by such a steering system.

[0005] It relates more particularly to an orientation system allowing the rotating part of the crane to be turned into a weather vane, and which is equipped with an additional braking device capable of being activated when the rotating part is turned into a weather vane to exert a braking torque on it, preventing uncontrolled rotation of the rotating part when it is turned into a weather vane.

[0006] The invention finds a preferred, and non-limiting, application in the field of tower cranes and element-mounted cranes.

[0007] [State of the art]

[0008] As is known, 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.

[0009] The rotating part comprises a boom on which the load is suspended by means of a lifting cable, the boom being able to be a distributing boom (on which a distributing trolley is movable in translation) and / or a luffing or tilting boom (movable between a horizontal lowered position and raised positions inclined relative to the horizontal). The rotating part may also comprise a counter-jib, which extends diametrically opposite the boom relative to the axis of orientation, and which is generally equipped with ballast.

[0010] The orientation of the rotating part, in other words its rotation around the orientation axis, is controlled by a slewing system. This slewing system typically includes 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 with a movable ring secured to the rotating part, rings between which balls or cylindrical rollers are mounted.

[0011] The orientation system further comprises, to control 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 comprising at least one orientation motor coupled to a reduction gear and rotating a pinion with a vertical axis which is engaged with a toothed wheel cut in the fixed ring of the orientation crown. 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.

[0012] The slewing gear motor usually has an internal brake, here called a main slewing brake, which is controlled by an electromagnet. When the slewing gear motor is stopped, the coil of the electromagnet is not electrically powered, and a braking torque is exerted to lock the rotating part in rotation. On the other hand, when the electromagnet is electrically powered, no braking torque is exerted by this main slewing brake. In the case of several slewing gear motors, at least one of them is equipped with such a main slewing brake, which intervenes during the crane's working periods.

[0013] Thus, this main slewing brake is designed to be deactivated for wind vaning of the rotating part, that is to say when the crane is "out of service", outside its working periods. This wind vaning means that the slewing gear motor is disengaged to allow the rotating part to orient itself freely according to the wind direction. The counterjib is then placed against the wind, while the boom orients itself in the direction of the wind, because the surface of the boom which is exposed to the wind is greater than that of the counterjib. In situation, to allow the crane to wind vane, the crane operator deactivates the main slewing brake when he leaves his work station.

[0014] 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 deep valley, to the point that the rotating part of the crane can enter unstable states, with uncontrolled rotation of the rotating part.

[0015] For example, the speed and force of the wind hitting the counterjib may be very different from the speed and force of the wind simultaneously hitting the boom. This difference between the rotational torque applied to the boom and the rotational torque applied to the counterjib may then become much greater than the friction torque of the slewing ring, so that the rotating part of the crane, instead of moving in the direction of the wind, will start rotating in a certain direction, without stopping. Thus, the crane is in an unstable state of autorotation (also called self-gyrating state), in which the rotating part cannot weathervane properly, and is driven into an uncontrolled rotation. In such an unstable state, there is a risk of the crane falling, especially if a gust of wind hits the rotating part when this part is oriented perpendicular to the wind direction.

[0016] To prevent uncontrolled rotation of the rotating part of the crane when the latter is installed on such a site, subject to disturbed winds, and therefore to avoid the risk of the crane falling, a solution has already been proposed in document EP2025637, which consists of inserting, in the slewing mechanism, an additional brake which, when the crane is wind-vaned, exerts a permanent braking torque, sufficient to prevent uncontrolled rotation of the rotating part, while still allowing wind-vaning. This solution is, however, impractical to implement.

[0017] It is also known from document EP2123592 to use additional braking means capable of being activated when the crane is put out of service to exert on the rotating part of the crane a braking torque preventing uncontrolled rotation of this rotating part when turning, where such additional braking means are incorporated in the slewing geared motor or in one of the slewing geared motors, in the form of an internal auxiliary brake inserted between the motor and the reducer.As described in this document, this internal auxiliary brake, inserted between the motor and the reducer, is a single disc brake controlled by an electromagnet, this brake being electrically powered so as not to brake the rotation of the rotating part of the crane when the crane is in operation, but exerting a braking torque by means of 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 put into weather vane.

[0018] 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 operation of the crane on site; in fact, the more the disc brake is used, the more the brake disc wears by friction, and therefore its thickness decreases. Thus, with time and wear, the compression spring loses its thrust force, therefore the braking torque decreases, and therefore the maximum possible speed for the rotating part increases in the event of uncontrolled rotation when it is weathervaned. Another disadvantage is that the braking torque exerted by this disc brake is permanent, which can prevent the rotating part from aligning with the wind for low wind speeds.

[0019] [Summary of the invention]

[0020] The present invention aims to resolve all or part of the aforementioned drawbacks by means of an additional braking device which, when the rotating part is placed in a weather vane, 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, even critical, wind speeds likely to cause it to tip into uncontrolled rotation.

[0021] Another aim 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.

[0022] To this end, the invention proposes an orientation system for controlling an orientation of a rotating part of a crane, this orientation system comprising at least:

[0023] - 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;

[0024] - a main orientation brake capable of being deactivated to turn the rotating part into a weather vane; and

[0025] - an additional braking device.

[0026] This orientation system is such that:

[0027] - in a service configuration, the slewing geared motor is engaged to be able to drive the rotation of the rotating part and the additional braking device is inactivated so as not to exert braking torque on the motor shaft; and

[0028] - in an out-of-service configuration, the orientation gear motor is disengaged and the main orientation brake is deactivated to turn the rotating part in order to be able to turn freely according to the wind direction, and the additional braking device is capable of being activated when the rotating part is turned in order to exert on the motor shaft a braking torque opposite to an orientation torque exerted by the rotating part on the motor shaft.

[0029] Also, it is quite clear, within the meaning of the invention, that the orientation system can occupy two distinct configurations, which are:

[0030] - the service configuration, which is such that the crane operator can rotate the rotating part by controlling the slewing gear motor which is engaged, so that the engine torque is transmitted from the motor shaft to the rotating part, and in this service configuration the additional braking device is inactivated so as not to brake the rotating part, only the main slewing brake being able to be activated if the crane operator wishes to stop the rotation of the rotating part; and

[0031] - the out-of-service configuration, which is such that the crane operator has disengaged the slewing gear motor and deactivated the main slewing brake, so that the rotating part is free to rotate and can thus align itself with the wind direction (this is called weathervaning the rotating part), and only the additional braking device can be activated to be able to brake or slow down the rotating part so as to prevent uncontrolled rotation of the rotating part, while still allowing weathervaning.

[0032] Thus, it is clear that this additional braking device is inactivated in the service configuration and therefore does not intervene to brake or slow down the rotating part when the slewing gear motor is engaged.

[0033] This steering system is remarkable in that the additional braking device includes:

[0034] - a bidirectional hydraulic motor mechanically coupled to the motor shaft of the slewing motor in order to be able to apply the braking torque to the motor shaft in both directions of rotation, said bidirectional hydraulic motor comprising a first hydraulic port and a second hydraulic port so that the slewing torque in the clockwise direction, respectively the counterclockwise direction, leads to a control pressure at the outlet of the first hydraulic port, respectively at the outlet of the second hydraulic port; and

[0035] - a hydraulic circuit connected between the first hydraulic port and the second hydraulic port; wherein the hydraulic circuit is configurable between:

[0036] - an inactive configuration in which pressure balancing is established between the first hydraulic port and the second hydraulic port, so that the additional braking device is inactivated and does not exert braking torque on the motor shaft; and

[0037] - 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 motor shaft according to the pressure regulation.

[0038] Thus, it is proposed to use an additional braking device which is hydraulic and which comprises a bidirectional hydraulic motor which can exert a braking torque in both directions of rotation when it is activated (hydraulic circuit in active configuration) to avoid or limit uncontrolled rotation of said rotating part when turning, and which does not exert a braking torque when it is inactivated (hydraulic circuit in inactive configuration).

[0039] 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 motor shaft when this rotating part is in a weather vane) is transmitted to the bidirectional hydraulic motor so as to have a control pressure (which results in an overpressure) at one of the two hydraulic ports and therefore at the inlet of the hydraulic circuit. For a steering torque, the additional braking device exerts a braking torque (which is opposite to the steering torque) by creating a pressure regulator to create a pressure differential which generates the braking torque.

[0040] The braking torque can be exerted when the steering torque (which corresponds to the torque exerted by the rotating part which is 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 higher the steering torque exerted by the rotating part on the motor shaft, and therefore the greater the control pressure.

[0041] The low torque threshold (or associated minimum wind speed) and / or the high torque threshold (or 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 turning torque, and therefore the higher the turning torque transmitted to the bidirectional hydraulic motor, and therefore the greater the control pressure on one of the two hydraulic ports (depending on the direction of rotation). According to one characteristic, the additional braking device is a passive device without a hydraulic pump.

[0042] It is passive in the sense that the hydraulic circuit does not include a hydraulic pump because, as already described, the control pressure corresponds to the pressure at one of the two hydraulic ports and therefore at the inlet of the hydraulic circuit, and it is this pressure which is regulated to create the pressure differential which generates the braking torque, without the need for a hydraulic pump to generate a control pressure and / or a pressure differential.

[0043] In a particular embodiment, the hydraulic circuit comprises:

[0044] - a main loop connecting the first hydraulic port to the second hydraulic port;

[0045] - a secondary loop connecting the first hydraulic port to the second hydraulic port, and on which a pressure regulating assembly is provided; in which said hydraulic circuit comprises a main distributor arranged on the main loop and adjustable between:

[0046] - an open position establishing a main fluid communication on the main loop, so that the hydraulic circuit is in the inactive configuration; and

[0047] - a closed position cutting off the main fluid communication on the main loop and establishing a secondary fluid communication on the secondary loop through the pressure regulation assembly, so that the hydraulic circuit is in the active configuration.

[0048] Thus, the pressure regulation assembly ensures pressure regulation to, if necessary, control the pressure differential between the first hydraulic port and the second hydraulic port and thus generate the braking torque.

[0049] According to one possibility, the pressure regulation assembly comprises, on the secondary loop, a leak regulation device having a predefined low pressure threshold and configurable between:

[0050] - a closed position, when the control pressure is higher than the low pressure threshold, in which the leakage control device is closed; and

[0051] - an open position, when the control pressure is below the low pressure threshold, in which the leakage control device is open and allows leakage at a leakage pressure which is equivalent to the control pressure.

[0052] 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 we want the leakage control device to be open so as not to exert braking torque.

[0053] This leakage control device allows the pressure to escape without blocking the orientation of the motor shaft when the control pressure is lower than the low pressure threshold, and therefore allows the rotation of the rotating part not to be 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, thus ensuring free orientation in the wind of the rotating part as long as the slewing torque is low (or as long as the wind speed is low, below the minimum wind speed), that is to say as long as the control pressure is lower than the low pressure threshold. Adjusting this low pressure threshold therefore makes it possible to adjust the minimum threshold speed below which the crane is free to align itself in the wind.

[0054] Alternatively, the pressure regulation assembly includes, on the secondary loop, a proportional pressure regulation valve set to a high pressure threshold and configurable between:

[0055] - a closed position, when the control pressure is lower than the high pressure threshold, in which the proportional pressure regulating valve is closed; and

[0056] - an open position, when the control pressure is higher than the high pressure threshold, in which the proportional pressure regulating valve is open and leaks at a regulating pressure which is proportional and lower than the control pressure.

[0057] 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 we want the proportional pressure control valve to be open to exert a braking torque proportional to the steering torque (or proportional to the wind speed).

[0058] This proportional pressure regulating valve is advantageous because, when the control pressure is higher than the high pressure threshold (and therefore when the wind speed exceeds the maximum wind speed), then the proportional pressure regulating valve regulates the pressure so that the pressure regulating assembly applies a braking torque which is proportional to the steering torque (and therefore to the pressure generated by the rolling of the oil flow passing through this proportional pressure regulating valve). Thus, this proportional pressure regulating valve allows the rotating part not to gain too much speed and therefore to limit the storage of kinetic energy which, if it were too great, could restart the rotating part on a rotational revolution, leading to the phenomenon of unwanted autorotation.

[0059] Such a proportional pressure regulating valve is therefore advantageous for allowing or not allowing a permanent sliding of the orientation at low speed, in order to permanently allow the placement of the rotating part in the direction of the wind. Indeed, depending on the setting of the proportional pressure regulating valve, the latter allows, despite the engagement of the bidirectional hydraulic motor, to let the pressure escape or not without blocking the orientation of the motor shaft.

[0060] In other words, the proportional pressure regulating valve acts as a regulator to prevent the rotation of the rotating part from accelerating too quickly.

[0061] According to one feature, the leakage control device and the proportional pressure control valve are arranged on parallel branches of the secondary loop.

[0062] According to another characteristic, the low pressure threshold is equal to the high pressure threshold.

[0063] Thus, the proportional pressure regulating valve directly takes over from the leakage regulating device when the control pressure increases and exceeds the low pressure threshold.

[0064] In this way, if the wind rises but is not strong, then the control pressure, regardless of the direction of rotation, does not exceed the low pressure threshold, and therefore the leakage control device fulfills its leakage role so that the rotating part follows the direction of the wind. If the wind force increases, the orientation torque also increases, and therefore the control pressure increases and exceeds the low pressure threshold and therefore exceeds the high pressure threshold of the proportional pressure control valve; and therefore this proportional pressure control valve comes into action by controlling the regulation pressure by flow management proportionally to the control pressure (the more the control pressure increases, the more the braking torque increases and therefore the more the rotating part is braked).

[0065] According to a variant, the low pressure threshold is strictly lower than the high pressure threshold.

[0066] 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. When the control pressure exceeds the low pressure threshold, without reaching the high pressure threshold, the leakage regulating device and the proportional pressure regulating valve are closed, and therefore the rotating part is locked in its position (and therefore does not align in the wind) until the control pressure increases further (in other words until the wind speed increases further). If the wind force increases and causes the steering torque to exceed the high torque threshold and therefore the control pressure to exceed the high pressure threshold, then the proportional pressure regulating valve comes into action and plays its role as a regulator to prevent the rotation of the rotating part from accelerating too quickly.

[0067] Alternatively, the pressure regulation assembly includes, on the secondary loop, a control pressure limiter having a safety pressure threshold and configurable between:

[0068] - a closed position, when the control pressure is lower than the safety pressure threshold, in which the control pressure limiter is closed; and

[0069] - an open position, when the control pressure is higher than the safety pressure threshold, in which the control pressure limiter is open and allows leakage at a control pressure equivalent to the control pressure.

[0070] 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 go into the wind without any other condition, in order to avoid damage and a risk of falling in the event of strong gusts of wind.

[0071] Advantageously, an energy dissipator, such as a heat exchanger, is placed on the secondary loop for dissipation of energy generated by hydraulic throttling at least in the check valves and the control pressure limiter.

[0072] According to one feature, the leakage control device and the control pressure limiter are arranged on parallel branches of the secondary loop.

[0073] Advantageously, the low pressure threshold is strictly lower than the safety pressure threshold.

[0074] According to another feature, the proportional pressure regulating valve and the control pressure limiter are arranged on parallel branches of the secondary loop. Advantageously, the high pressure threshold is strictly lower than the safety pressure threshold.

[0075] Advantageously, the leakage control device, the proportional pressure control valve and the control pressure limiter are arranged on parallel branches of the secondary loop.

[0076] In a particular embodiment, non-return valves are provided on the secondary pipe to direct the control pressure in the pressure regulating assembly regardless of the direction of rotation of the motor shaft.

[0077] These check valves allow the flow of oil to be directed into the pressure regulating assembly, regardless of the direction of rotation of the motor shaft, in other words regardless of the hydraulic port under overpressure; the oil flowing from the hydraulic port under overpressure to the other hydraulic port is directed through the pressure regulating assembly by means of the check valves.

[0078] In a particular embodiment, an energy dissipator, such as for example a heat exchanger, is in communication with the secondary loop for dissipating energy generated by hydraulic throttling at least in the pressure regulation assembly.

[0079] Such an energy dissipater thus allows for dissipation of the energy produced by braking (by a lamination effect of the hydraulic oil).

[0080] In a particular embodiment, the main distributor comprises a first inlet and a second inlet, and a first outlet and a second outlet, where communications are cut off between the first inlet and the first outlet and between the second inlet and the second outlet in the open position, and where communications are established between the first inlet and the first outlet and between the second inlet and the second outlet in the closed position.

[0081] In a particular embodiment, the main loop comprises:

[0082] - a first main inlet line connecting the first hydraulic port to the first inlet of the main distributor,

[0083] - a second main inlet line connecting the second hydraulic port to the second inlet of the main distributor,

[0084] - 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 non-return valves, called the first valve, arranged to block the circulation in the direction of the first outlet of the main distributor, and

[0085] - 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 non-return valves, called the second valve, arranged to block the circulation towards the first outlet of the main distributor.

[0086] According to one possibility, the secondary loop includes:

[0087] - an upstream line and a downstream line between which the pressure regulation assembly is placed;

[0088] - a first secondary inlet line connecting the first hydraulic orifice to the upstream line, and on which is placed one of the non-return valves, called the third valve, arranged to block the circulation towards the first hydraulic orifice;

[0089] - a second secondary inlet line connecting the second hydraulic orifice to the upstream line, and on which is placed one of the non-return valves, called the fourth valve, arranged to block the circulation towards the second hydraulic orifice.

[0090] Alternatively, the leakage control device is placed on a leakage branch which is arranged between the upstream line and the downstream line.

[0091] According to a variant, the proportional pressure regulating valve is placed on a regulating branch between the upstream line and the downstream line.

[0092] According to another variant, the control pressure limiter is placed on a control branch which is arranged between the upstream line and the downstream line.

[0093] According to one characteristic, the secondary loop comprises:

[0094] - 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

[0095] - a second secondary output line connecting the downstream line to the second output of the main distributor.

[0096] According to another characteristic, the energy dissipater is placed on the first secondary output line or on the second secondary output line

[0097] In an advantageous embodiment, the main distributor has dual manual and electrical control.

[0098] Thus, the manual control will allow the action of the bidirectional hydraulic motor to be inhibited in the event that the orientation of the rotating part needs to be released, and the electric control will allow, when the crane is in service, the action of the bidirectional hydraulic motor to be inhibited.

[0099] 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.

[0100] [Brief description of the figures] Other characteristics and advantages of the present invention will appear on reading the detailed description below, of several non-limiting examples of implementation, made with reference to the appended figures in which:

[0101] Figure 1 is a schematic view of a crane equipped with an orientation system according to the invention, with a zoom on this orientation system;

[0102] Figure 2 is a schematic view of an orientation system comprising a hydraulic circuit according to a first embodiment, in an inactive configuration;

[0103] Figure 3 is a schematic view of the orientation system of Figure 2, in an active configuration with a control pressure below the low leakage pressure threshold, this maximum leakage pressure threshold being equal to the high pressure threshold;

[0104] Figure 4 is a schematic view of the orientation system of Figure 2, in an active configuration with a control pressure above the low leakage pressure threshold and the high pressure threshold, but also below the safety pressure threshold;

[0105] Figure 5 is a schematic view of the steering system of Figure 2, in an active configuration with a control pressure above the safety pressure threshold;

[0106] Figure 6 is a schematic view of the orientation system of Figure 2, in an active configuration with a control pressure greater than the low leakage pressure threshold and less than the high pressure threshold, this maximum leakage pressure threshold being strictly less than the high pressure threshold;

[0107] Figure 7 is a schematic view of the steering system of Figure 2, in an active configuration with a control pressure above the high pressure threshold, but also below the safety pressure threshold;

[0108] Figure 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 lower than the safety pressure threshold;

[0109] Figure 9 is a schematic view of an orientation system comprising a hydraulic circuit according to a third embodiment, in an inactive configuration.

[0110] [Detailed description of several embodiments of the invention]

[0111] With reference to Figure 1, a crane 8, here a tower crane, comprises a rotating part 9 which is orientable around a vertical orientation axis 90, as shown diagrammatically by the double arrow “91”. This rotating part 9 is movable in rotation on the top 82 of a mast 80 (also called tower) of vertical extension, where the mast 80 has a base 81 which rests on the ground.

[0112] This rotating part 9 comprises a pivot assembly 92 rotatably mounted on the top 82 of the mast 80 along the orientation axis 90, as well as 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.

[0113] The rotating part 9 may also comprise a counter-jib 95 mounted on the pivot assembly 92, opposite the jib 93, and one or more ballasts 96 may be mounted on the counter-jib 95. The rotating part 9 further comprises a pilot cabin 97, placed on the pivot assembly 92 at the foot of the jib 93. It is conceivable to have a jib holder 98 or punch which is mounted vertically on the pivot assembly 92, to carry the jib 93, and possibly the counter-jib 95, for example by means of shrouds.

[0114] 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 comprises an orientation ring 10 whose function is to pivotally connect the pivot assembly 92 of the rotating part 9 to the top 82 of the mast 80.

[0115] 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 secured to the pivot assembly 92. Bearings or cylindrical rollers are mounted rolling between the two concentric rings 11, 12. The fixed ring 11 is in the form of a toothed crown.

[0116] The orientation system 1 further comprises, 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.

[0117] This orientation geared motor 13 comprises an orientation motor 14 having a motor shaft 15 (shown diagrammatically in Figures 2 to 7), and an orientation reducer 16 coupled to the motor shaft and driving in rotation a pinion 17 with a vertical axis which is engaged with the teeth provided on the fixed ring 11 of the orientation crown 10. The orientation system 1 comprises a variator (not shown) connected to the orientation motor to adjust its speed and its torque.

[0118] Depending on the mechanical power to be transmitted to rotate the rotating part 9, it is possible to provide one or more slewing geared motors on the rotating part 9. In the example illustrated in Figure 1, another slewing geared motor 13' is provided on the rotating part 9. The slewing system 1 comprises a main slewing brake 18 which is formed by an internal brake of the slewing geared motor 13, or by 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 coil of the electromagnet is not electrically powered, and a braking torque is exerted to lock the rotating part 9 in rotation. On the other hand, when the electromagnet is electrically powered, no braking torque is exerted by this main slewing brake 18.

[0119] Thus, this main slewing brake 18 is designed to be deactivated for wind vaning of the rotating part 9, that is to say when the crane 8 is “out of service”, outside its working periods. This wind vaning means that the slewing gear motor 13 is disengaged to allow the rotating part 9 to orient itself freely according to the direction of the wind. In this situation, to allow the crane 8 to wind vane, the crane operator deactivates the main slewing brake 18 when he leaves his work station.

[0120] Crane 8 also includes a control / command unit (not shown) connected:

[0121] - 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;

[0122] - to the main orientation brake 18 in order to actuate this brake to block or release the orientation of the rotating part 9.

[0123] The orientation system 1 of the crane 8 is thus configurable between:

[0124] - a service configuration in which the rotating part 9 can be controlled in rotation on the mast 80 along the orientation axis 90 by controlling the orientation system 1 by means of the control / command unit, and more precisely in which the orientation geared motor 13 is engaged to be able to drive the rotation of the rotating part 9; and

[0125] - an out-of-service configuration in which the rotating part 9 is released in rotation on the mast 80 along the orientation axis 90 to be able to orient itself in the direction of the wind, the main orientation brake 18 being deactivated and the orientation gear motor 13 of the orientation system 1 being disengaged in the out-of-service configuration for weathervaning of the rotating part 9.

[0126] The slewing system 1 comprises an additional braking device 2 capable of being activated when the rotating part 9 is turned to exert a braking torque on the motor shaft 15 of the slewing gear motor 13, with the aim of slowing down or at least braking the rotation of the rotating part 9 when it is turned to prevent uncontrolled rotation thereof. When the slewing system 1 of the crane 8 is in the service configuration, this additional braking device 2 is not activated (in other words it is inactivated), so as not to exert a braking torque.

[0127] 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 undergoes a thrust from the wind which results in a steering torque CO exerted by the rotating part 9 on the motor shaft 13. The braking torque exerted by the additional braking device 2 is therefore opposite 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).

[0128] This additional braking device 2 is a hydraulic device, which comprises a bidirectional hydraulic motor 20 mechanically coupled to the motor shaft 15 of the slewing motor 14 in order to be able to apply the braking torque to the motor shaft 15 in both directions of rotation. Thus, the slewing torque CO is transmitted by the motor shaft 13 to the bidirectional hydraulic motor 20 which in response (as described below) exerts the braking torque opposite to the slewing torque CO.

[0129] This additional hydraulic motor 20 comprises a first hydraulic port 21 and a second hydraulic port 22, such that the orientation torque CO:

[0130] - in a clockwise direction, leads to a control pressure P (in other words an overpressure) at the outlet of the first hydraulic orifice 21; and

[0131] - counterclockwise, leads to a control pressure P (in other words an overpressure) at the outlet of the second hydraulic orifice 22.

[0132] 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:

[0133] - an inactive configuration in which a pressure balance is established 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 inactivated and does not exert any braking torque on the motor shaft 15; and

[0134] - an active configuration in which a pressure regulation is established to control a pressure differential between the first hydraulic orifice 21 and the second hydraulic orifice 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.

[0135] As can be seen, the hydraulic circuit 3 of the additional braking device 2 does not include a hydraulic pump, so that the additional braking device 2 is a passive device without a hydraulic pump. Indeed, and as described in more detail below, the additional braking device 2 is shaped to react to the control pressure P (which depends on the orientation torque CO exerted by the rotating part 9 in a weather vane and therefore free to rotate) and to regulate this control pressure P autonomously, without the need for a hydraulic pump; which has the advantage of having an additional braking device 2 that is particularly responsive, efficient and reliable.

[0136] In the first embodiment of Figures 2 to 7, the second embodiment of Figure 8 and the third embodiment of Figure 9, the hydraulic circuit 3 comprises:

[0137] - a main loop 31 connecting the first hydraulic port 21 to the second hydraulic port 22;

[0138] - 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.

[0139] The hydraulic circuit 3 comprises a main distributor 6 arranged on the main loop 30 and adjustable between:

[0140] - an open position (in Figure 2) establishing a main fluid communication on the main loop 31, so that the hydraulic circuit 3 is in the inactive configuration; and

[0141] - a closed position (in Figures 3 to 9) cutting the main fluid communication on the main loop 31 and establishing a secondary fluid communication on the secondary loop 32 through the pressure regulation assembly 4, so that the hydraulic circuit 3 is in the active configuration.

[0142] The hydraulic circuit 3 comprises non-return 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.

[0143] In the first embodiment of Figures 2 to 7, the pressure regulation assembly 4 comprises, on the secondary loop 32, a leak regulation device 41 having a predefined low pressure threshold PI and configurable between: - a closed position, when the control pressure P is greater than the low pressure threshold PI, in which the leak regulation device 41 is closed; and

[0144] - an open position, when the control pressure P is lower than the low pressure threshold PI, in which the leakage control device 41 is open and allows leakage at a leakage pressure which is equivalent to the control pressure P.

[0145] This low pressure threshold PI is associated with a low torque threshold Cl for the orientation 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 as a function of the minimum wind speed VI below which (or as a function of the low torque threshold Cl below which) we want the leakage control device 41 to be open so as not to exert braking torque.

[0146] In other words, when the control pressure P is lower than the low pressure threshold PI (i.e. when the wind speed V is lower than the minimum wind speed VI or when the steering torque CO is lower than the low torque threshold Cl), the leakage control device 41 is open, and thus the control pressure P leaks through this leakage control device 41, thus balancing the pressures between the first hydraulic port 21 and the second hydraulic port 22, and therefore the braking torque is zero.

[0147] In the first embodiment of Figures 2 to 7, the pressure regulation assembly 4 comprises, on the secondary loop, a proportional pressure regulation valve 42 calibrated to a high pressure threshold P2 and configurable between:

[0148] - a closed position, when the control pressure P is lower than the high pressure threshold P2, in which the proportional pressure regulating valve 42 is closed; and

[0149] - an open position, when the control pressure P is higher than the high pressure threshold P2, in which the proportional pressure regulating valve 42 is open and allows leakage at a regulating pressure which is proportional and lower than the control pressure P.

[0150] 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 as a function of the maximum wind speed V2 above which (or as a function of the high torque threshold C2 above which) we want the proportional pressure regulating valve 42 to be open to exert the braking torque.In other words, when the control pressure P is greater than the high 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 high 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 and lower 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 motor shaft 13 and therefore on the rotating part 9.

[0151] 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:

[0152] - a closed position, when the control pressure P is lower than the safety pressure threshold P3, in which the control pressure limiter 43 is closed; and

[0153] - an open position, when the control pressure P is higher than the safety pressure threshold P3, in which the control pressure limiter 43 is open and allows leakage at a control pressure equivalent to the control pressure P.

[0154] This safety pressure threshold P3 is associated with a safety torque threshold C3 for the steering 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 as a function of the safety wind speed V3 above which (or as a function of the safety torque threshold C3 above which) the control pressure limiter 43 is wanted to be open so as not to exert braking torque and allow the rotating part to spin.

[0155] 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 the control pressure limiter 43, thereby balancing the pressures between the first hydraulic port 21 and the second hydraulic port 22, and thus the braking torque is zero.

[0156] In the first embodiment of Figures 2 to 7, the leakage 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.

[0157] More specifically, the main distributor 6 is a 4 / 2 distributor, for example with dual manual and electrical 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:

[0158] - 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

[0159] - 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.

[0160] In the first embodiment of Figures 2 to 7 and in the second embodiment of Figure 8, the main loop 31 comprises:

[0161] - a first main inlet line 311 connecting the first hydraulic orifice 21 to the first inlet 61 of the main distributor 6,

[0162] - a second main inlet line 312 connecting the second hydraulic port 22 to the second inlet 62 of the main distributor 6,

[0163] - a first main outlet line 313 connecting the first hydraulic orifice 21 to the first outlet 63 of the main distributor 6, and on which is placed one of the non-return valves, called first valve 51, arranged to block the circulation in the direction of the first outlet 63 of the main distributor 6, and

[0164] - a second main outlet line 314 connecting the second hydraulic orifice 22 to the first outlet 63 of the main distributor 6, and on which is placed one of the non-return valves, called second valve 52, arranged to block the circulation in the direction of the first outlet 63 of the main distributor 6.

[0165] In the first embodiment of Figures 2 to 7 and in the second embodiment of Figure 8, the secondary loop 32 comprises:

[0166] - an upstream line 321 and a downstream line 322 between which the pressure regulation assembly 4 is placed;

[0167] - 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 the circulation in the direction of the first hydraulic orifice 21;

[0168] - 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 non-return valves, called fourth valve 54, arranged to block the circulation in the direction of the second hydraulic orifice 22. In the first embodiment of Figures 2 to 7, the leakage regulation device 41 is placed on a leakage branch 325 which is arranged between the upstream line 321 and the downstream line 322, and between the two non-return valves 53, 54.

[0169] The proportional pressure regulating valve 42 is placed on a regulating branch 326 which is arranged between the upstream line 321 and the downstream line 322, and between the two non-return valves 53, 54.

[0170] The control pressure limiter 43 is placed on a control branch 327 which is arranged between the upstream line 321 and the downstream line 322, and between the two non-return valves 53, 54.

[0171] In the first embodiment of Figures 2 to 7 and in the second embodiment of Figure 8, the secondary loop 32 comprises:

[0172] - 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

[0173] - a second secondary output line 329 connecting the downstream line to the second output 64 of the main distributor 6.

[0174] An energy dissipator 71 is placed on the secondary loop 32, and more precisely on the first secondary output line 328 or on the second secondary output line 329. This energy dissipator 71, such as for example a heat exchanger, is therefore in communication with the secondary loop 32 for dissipation of energy generated by hydraulic throttling in the pressure regulation assembly 4.

[0175] A hydraulic accumulator 72 is placed on the secondary loop 32, and more precisely on the upstream line 321.

[0176] In a first use of the hydraulic circuit 3 of the first embodiment, the low pressure threshold PI is equal to the high pressure threshold P2, for example at a value of 10 bars, and the safety pressure threshold P3 is greater than the low pressure threshold PI and the high pressure threshold P2, for example with a value of 300 bars. The values ​​of these thresholds PI, P2, P3 are established as a function of the torque thresholds C1, 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.

[0177] In this first use, the crane 8 being in its out-of-service configuration (therefore the rotating part 9 is put in 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. With reference to Figure 3, when the wind is zero or low (that is to say that the wind speed V is lower than the minimum wind speed VI which is, as a reminder, equal to the maximum wind speed V2) and therefore the orientation torque CO exerted by the rotating part 9 is zero or lower than the low torque threshold Cl which is equal to the high torque threshold C2, then the control pressure P is lower 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.Thus, the control pressure P leaks through the leakage regulating device 41 and therefore the rotating part 9 aligns in the wind without being braked by the additional braking device 2.

[0178] With reference to Figure 4, when the wind force increases and therefore the wind speed V becomes greater than the minimum wind speed VI (which is, as a reminder, 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 low torque threshold Cl which is equal to the high torque threshold C2 without reaching the safety torque threshold C3, then the control pressure P exceeds the low pressure threshold PI (and therefore also the high 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, 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.

[0179] With reference to Figure 5, when the wind force becomes too great and therefore the wind speed V becomes greater than the safety wind speed V3, and therefore 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 in the wind without being braked by the additional braking device 2.

[0180] This scenario is considered when a gust of wind tends to push the rotating part 9 very strongly, with a wind speed higher than the safety wind speed V3 (for example when this rotating part 9 is perpendicular to the wind direction), and it is in this case necessary to let the rotating part 9 align in the wind without braking torque. In this situation of Figure 5, the proportional pressure regulating valve 42 is not able to evacuate the entire hydraulic flow generated by this sudden acceleration, and it is therefore at this moment that the control pressure limiter 43 plays the role of safety valve by bringing the circuit pressure back 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 Figure 4.

[0181] In a second use of the hydraulic circuit 3 of the first embodiment, the low pressure threshold PI is set very low (for example at a value of 1 bar to be closed almost constantly), the high pressure threshold P2 is strictly higher than the low pressure threshold PI, for example at a value of 50 bars, and the safety pressure threshold P3 is strictly higher than the high pressure threshold P2, for example with a value of 55 bars. The values ​​of these thresholds PI, P2, P3 are established as a function of the torque thresholds C1, 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.

[0182] In this second use, the crane 8 being in its out-of-service configuration (therefore the rotating part 9 is put into 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.

[0183] With reference to Figure 6, the wind picks up, it is not powerful but it is sufficient for the wind speed V to exceed the minimum wind speed VI, without reaching the maximum wind speed V2, and therefore the rotating part 9 begins to rotate gently and the orientation torque CO almost immediately exceeds the low torque threshold Cl without reaching the high torque threshold C2, then the control pressure P exceeds the low pressure threshold PI, without yet reaching the high pressure threshold P2 - in summary V1 <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 de fuite 41 est fermé, la valve de régulation de pression proportionnelle 42 est fermée et le limiteur de pression de contrôle 43 est fermé.Therefore the rotating part 9 is strongly braked, to the point of being stopped in its rotation, because the control pressure P cannot circulate freely due to the closure of these three regulation means 41, 42, 42, due to the low calibration of the leakage regulation device 41. If the wind continues to increase, it exerts a force on the rotating part 9 and therefore the pressure increases, but as long as the control pressure P does not reach the high pressure threshold P2 (in other words as long as the wind speed V does not exceed the maximum wind speed V2), then the rotating part 9 will remain fixed in its position, until the control pressure P exceeds this high pressure threshold P2.

[0184] With reference to Figure 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 high torque threshold C2 without reaching the safety torque threshold C3, then the control pressure P exceeds the high 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 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. Ainsi, valve de régulation de pression proportionnelle 42 entre en action pour exercer le couple de freinage (comme décrit précédemment en référence à la Figure 4).

[0185] 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 previously described with reference to Figure 5).

[0186] Thus, in this second use, the position of the rotating part 9 as left by the crane operator when setting the wind vane, 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 block the rotating part 9 for a low wind (below the maximum wind speed V2), and to allow the rotating part 9 to turn in the direction of the wind from a predefined wind level (above the maximum wind speed V2).

[0187] In the second embodiment of Figure 8, the pressure regulating assembly 4 comprises, on the secondary loop 32, a flow regulating valve 44 for reducing the pressure.

[0188] In the second embodiment of Figure 8, the pressure regulating assembly 4 comprises, on the secondary loop 32, a control pressure limiter 43 as described previously.

[0189] In the second embodiment of Figure 8, the flow control valve 44 and the control pressure limiter 43 are arranged on parallel branches of the secondary loop 32.

[0190] The hydraulic circuits 3 of the first embodiment of Figures 2 to 7 and the second embodiment of Figure 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 non-return valves 51, 52, 53, 54, the same energy dissipater 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.

[0191] In the second embodiment of Figure 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.

[0192] In operation, in the out-of-service configuration of the crane 8, as long as the wind speed V is lower than the safety wind speed V3, and therefore the orientation torque CO exerted by the rotating part 9 is lower than the safety torque threshold C3, then the flow control valve 44 makes it possible to brake the rotating part 9, according to its setting.

[0193] 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.

[0194] The first regulation subassembly 411 comprises in parallel a first flow regulation valve 441, a first control pressure limiter 431 and a first non-return valve 55. The second regulation subassembly 412 comprises in parallel a second flow regulation valve 442, a second control pressure limiter 432 and a second non-return valve 56. The first control pressure limiter 431 and the second control pressure limiter 432 each have the same safety pressure threshold P3.

[0195] In the third embodiment of Figure 9, the main loop 31 comprises:

[0196] - a first main inlet line 311 connecting the first hydraulic orifice 21 to the first inlet 61 of the main distributor 6,

[0197] - a second main inlet line 312 connecting the second hydraulic port 22 to the second inlet 62 of the main distributor 6,

[0198] - a first main outlet line 333 connecting the first hydraulic orifice 21 to the first outlet 63 of the main distributor 6, and on which the first regulation subassembly 411 is placed, the first non-return valve 55 being arranged to block the circulation in the direction of the first outlet 63 of the main distributor 6, and

[0199] - a second main outlet line 334 connecting the second hydraulic orifice 22 to the second outlet 64 of the main distributor 6, and on which the second regulation sub-assembly 412 is placed, the second non-return valve 56 being arranged to block the circulation towards the second outlet 64 of the main distributor 6.

[0200] The secondary loop 32 comprises the parallel branches of the regulation sub-assemblies 411, 412, on which are placed the flow regulation valves 441, 442, the control pressure limiters 431, 432 and the non-return valves 55, 56.

[0201] An energy dissipator 71 is placed on the secondary loop 32, and more precisely 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.

[0202] In this third embodiment of Figure 9, the crane 8 being in its out-of-service configuration (therefore the rotating part 9 is put into a weather vane), the operation of the hydraulic circuit 3, and therefore of the additional braking device 2, is described below.

[0203] When the motor shaft 15 rotates clockwise, and as long as the wind speed V is lower than the safety wind speed V3, and therefore the orientation torque CO exerted by the rotating part 9 is lower than the safety torque threshold C3, then the control pressure P is at the outlet of the first hydraulic orifice 21 and this control pressure P passes through the first regulation subassembly 411 so that the first flow regulation valve 441 makes it possible to brake the rotating part 9, according to its setting.

[0204] When the motor shaft 15 rotates counterclockwise, and as long as the wind speed V is lower than the safety wind speed V3, and therefore the orientation torque CO exerted by the rotating part 9 is lower than the safety torque threshold C3, then the control pressure P is at the outlet of the second hydraulic orifice 22 and this control pressure P passes through the second regulation subassembly 412 so that the second flow regulation valve 442 makes it possible to brake the rotating part 9, according to its setting.

[0205] 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 motor shaft 15, to leave the rotating part 9 free to rotate.

[0206] Alternatively, it is conceivable to replace the first flow control valve 441 with a first leak control device and a first proportional pressure control valve in parallel, and to replace the second flow control valve 442 with a second leak 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

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

2. Steering system (1) according to claim 1, wherein the additional braking device (2) is a passive device without a hydraulic pump.

3. Steering system (1) according to claim 1 or 2, 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; in which said hydraulic circuit (3) comprises a main distributor (6) arranged on the main loop (31) and adjustable between: - an open position establishing a main fluid communication on the main loop (31), so that the hydraulic circuit is in the inactive configuration; and - a closed position cutting off the main fluid communication on the main loop (31) and establishing a secondary fluid communication on the secondary loop (32) through the pressure regulation assembly (4), so that the hydraulic circuit is in the active configuration.

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

5. Orientation system (1) according to claim 3 or 4, in which the pressure regulation assembly (4) comprises, on the secondary loop (32), a proportional pressure regulation valve (42) calibrated 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 regulating valve (42) is closed; and - an open position, when the control pressure (P) is higher than the high pressure threshold (P2), in which the proportional pressure regulating valve (42) is open and lets out at a regulating pressure which is proportional and lower than the control pressure (P).

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

7. Orientation system (1) according to claim 6, in which the low pressure threshold (PI) is equal to the high pressure threshold (P2).

8. Orientation system (1) according to claim 6, in which the low pressure threshold (PI) is strictly lower than the high pressure threshold (P2).

9. Orientation system (1) according to any one of claims 3 to 8, in which 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 lower 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 higher than the safety pressure threshold (P3), in which the control pressure limiter (43; 431; 432) is open and allows leakage at a control pressure equivalent to the control pressure (P).

10. Guidance system (1) according to claims 4 and 9, wherein the leakage regulating device (41) and the control pressure limiter (43) are arranged on parallel branches (325, 327) of the secondary loop (32).

11. Guidance system (1) according to claim 10, in which the low pressure threshold (PI) is strictly lower than the safety pressure threshold (P3).

12. Steering system (1) according to claims 5 and 9, 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).

13. Orientation system (1) according to claim 12, in which the high pressure threshold (P2) is strictly lower than the safety pressure threshold (P3).

14. Steering system (1) according to claims 4, 5 and 9, wherein the leakage 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).

15. Orientation system (1) according to any one of claims 3 to 14, in which the pressure regulation assembly (4) comprises, on the secondary loop, a flow regulation valve (44; 441; 442).

16. Steering system (1) according to claims 9 and 15, 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).

17. Steering system (1) according to any one of claims 3 to 16, wherein non-return valves (51, 52, 53, 54; 55, 56) are provided on the secondary loop (32) to steer the control pressure (P) in the pressure regulating assembly (4) regardless of the direction of rotation of the motor shaft (15).

18. Steering system (1) according to any one of claims 3 to 17, wherein an energy dissipator (71), such as for example a heat exchanger, is in communication with the secondary loop (32) for dissipating energy generated by hydraulic rolling at least in the pressure regulating assembly (4).

19. Guidance system (1) according to any one of claims 3 to 18, 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), where 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 where 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.

20. Guidance system (1) according to claims 17 and 19, wherein the main loop (32) comprises: - a first main inlet line (311) connecting the first hydraulic orifice (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 orifice (21) to the first outlet (63) of the main distributor (6), and on which is placed one of the non-return valves, called the first valve (51), arranged to block the circulation in the direction of 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 non-return valves, called second valve (52), arranged to block the circulation in the direction of the first outlet (63) of the main distributor (6).

21. Guidance system (1) according to claim 20, wherein the secondary loop (32) comprises: - an upstream line (321) and a downstream line (322) between which the pressure regulation assembly (4) is placed; - 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 the circulation in the direction of 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 is placed one of the non-return valves, called the fourth valve (54), arranged to block the circulation towards the second hydraulic orifice (22).

22. Guidance system (1) according to claims 4 and 21, wherein the leakage control device (41) is placed on a leakage branch (325) which is arranged between the upstream line (321) and the downstream line (322).

23. Steering system (1) according to claims 5 and 21, wherein the proportional pressure regulating valve (42) is placed on a regulating branch (326) between the upstream line (321) and the downstream line (322).

24. Steering system (1) according to claims 9 and 21, wherein the control pressure limiter (43) is placed on a control branch (327) which is arranged between the upstream line (321) and the downstream line (322).

25. Guidance system (1) according to any one of claims 21 to 24, wherein 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 (322) to the second output (64) of the main distributor (6).

26. Guidance system (1) according to claims 18 and 25, wherein the energy dissipater (71) is placed on the first secondary output line (328) or on the second secondary output line (329).

27. Orientation system (1) according to any one of claims 3 to 26, in which the main distributor (6) has dual manual and electrical control.

28. Crane (8) comprising a rotating part (9) which is orientable around a vertical orientation axis (90), and comprising an orientation system (9) according to any one of the preceding claims, in which the rotation of the rotating part (9) is controlled by said orientation system (9).

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