HAND-OPERATED HYDRAULIC LIFTING DEVICE FOR LIFTING EQUIPMENT

Description

technical field

[0001] This application concerns a manually operated hydraulic lowering device for lifting equipment. State of the art

[0002] A lifting device such as a crane, overhead crane, etc., typically consists of a line equipped with a drum around which suspension cables are wound, to which the load to be lifted is attached. Such a lifting device can be used to lift extremely heavy loads, for example, weighing over 50 tons, and whose weight is sometimes not the only source of danger (the load may, for example, be radioactive material or a bucket filled with molten metal).

[0003] The lifting equipment needs to be equipped with brakes for several functions, including: slowing down and then stopping the load as it approaches a stopping position (service brake); locking the lifting equipment when it is in its stopping position, i.e., when the load is at the desired height (parking brake); stopping and locking the lifting equipment in the event of an electrical failure or, more generally, in any emergency (safety brake, also called emergency brake or " failsafe brake " in English).

[0004] A safety brake is specifically designed to activate when it loses power (in the event of a power outage): this is known as a fail-safe or negative brake. Disc brakes have become the standard since the 1960s for this purpose, in particular because they generate little to no heat.

[0005] A disc safety brake typically includes: a disc attached to the line to be braked, a clamp, comprising two plates suitable for clamping the disc, which plates are generally fitted with friction pads, for each plate or for one of the two plates only, a washer spring configured to impose a pressure force on said plate in the direction of closing the brake, that is to say so as to push and maintain under pressure the plates against the disc and thus clamp the clamp, an actuator, which can be electro-hydraulic or electromagnetic or even electromechanical, and which presses against one end of the washer spring so as to compress it in the direction of opening the brake; when the actuator is under tension, it compresses the washer spring, which opens the clamp and releases the rotating disc (and therefore the line).

[0006] In the event of a power failure, the actuator suddenly becomes inoperative, releasing the spring and washers which close the brake. The load is then stopped and remains suspended in mid-air.

[0007] The load must then be lowered, even though the power may still be out. This operation is carried out using a hydraulic lowering device, which slightly releases the safety brake, allowing the line to rotate and the load to be lowered.

[0008] Electromagnetic and electromechanical safety brakes are thus equipped with a hydraulic release chamber and a "hydraulic release" connection to which an operator can connect a hydraulic lowering unit when a lowering operation is required.

[0009] Being by definition managed by a hydraulic system, already integrated into the brake or not, hydraulic brakes include a main hydraulic chamber for the day-to-day management of the brake, and they are generally equipped with a "drop option" which allows you to take control of the hydraulic management system of the brake.

[0010] In all cases, the brake includes a hydraulic chamber into which a pressurized fluid (for example, oil) can be injected. This hydraulic chamber presses against one end of the brake's spring-loaded washer, compressing the spring in the direction of brake release. Throughout this document, this hydraulic chamber is referred to as the brake release chamber, including in the case of an electro-hydraulic brake, where the chamber serves not only as a release chamber but also as the brake's primary operating chamber.

[0011] In known brakes (whatever the nature of the brake), the lowering must be managed by an operator from the lifting bridge or the top of the crane, in an uncomfortable and dangerous posture because of the height.

[0012] In known brakes (regardless of the brake type), the hydraulic release device, either integrated into the brake or connected to it when a lowering operation is necessary, is equipped with a fluid reservoir, a hand-operated lever pump that delivers a volume of fluid when the lever is activated, and a flow restrictor that maintains a controlled, continuous leak to the reservoir. WO2015 / 110509 discloses such a hydraulic release device with a manually operated pump and crank.

[0013] The combination of the pump flow and the leakage flow generates a back pressure in the hydraulic chamber of the brake, which opposes the force of the washer spring via the hydraulic release device.

[0014] When the counter-pressure produces a force just greater than the pinching force sufficient to retain the load, sliding begins and the load descends.

[0015] Although functional on paper, in practice, adjusting the pressure in the hydraulic chamber is only possible by matching the pumping frequency to the leakage rate.

[0016] In order to balance the volume of fluid injected into the hydraulic chamber for releasing the brake, the operator must adjust the force and speed of pumping throughout the duration of the lowering, both of which vary according to the expected pressure, which causes stress, fatigue and risk.

[0017] Thus, existing lowering devices are very difficult to operate and do not allow for a slow and controlled lowering of the load. Indeed, they do not allow the operator to "feel" the pressure in the hydraulic brake chamber, nor to easily regulate this pressure. In practice, the lowering device can ultimately react in an all-or-nothing manner: while the brake is still engaged, a single additional action on the pump lever can cause a rapid and significant increase in pressure in the hydraulic release chamber, resulting in the brake opening and the subsequent drop of the load.

[0018] Furthermore, not only does the device lack means of controlling the pressure in the hydraulic release chamber, but once the equilibrium pressure is exceeded, the lowering device does not allow the operator to act to reduce in a controlled manner the quantity and / or pressure of fluid in the hydraulic chamber in order to slightly close the brake so as to slow the fall of the load.

[0019] Note that the "equilibrium pressure" of the brake refers to the fluid pressure in the hydraulic release chamber that compresses the spring (in the direction of brake opening) without lifting the brake pads from the disc. In other words, it's the fluid pressure that allows the hydraulic chamber to precisely counteract the force exerted by the spring on the caliper plates to retain the load. When this equilibrium pressure is reached in the hydraulic chamber, the load is no longer held by the brake, even though it is not fully released.

[0020] For the load to be lowered slowly, progressively and in a controlled manner, the pressure in the chamber must be both higher than this equilibrium pressure so that the brake plates do not exert a force that would block the disc, and close enough to it so that the plates press down sufficiently on the disc to slow the descent of the load. Description of the invention

[0021] The invention aims to overcome at least one of the aforementioned drawbacks by proposing a lowering device for lifting equipment, which allows a load to be lowered in a controlled and safe manner, and which is easy to maneuver and safe for the operator.

[0022] To this end, the invention proposes a hydraulic lowering device for a safety brake on a lifting machine, intended for use with a brake equipped with a hydraulic release chamber and a fluid inlet connection, referred to as the release connection. The lowering device comprises a fluid reservoir and a fluid outlet. The lowering device according to the invention is characterized in that it comprises: a pressurized fluid accumulator, connected to the fluid reservoir, a pump connected to the reservoir to inject under pressure into the accumulator the fluid present in the reservoir, a three-way pressure regulator comprising a mechanical control input for setting a setpoint value, a fluid inlet connected to the accumulator, a first fluid outlet connected to the fluid outlet of the lowering device, and a second fluid outlet, called drain, connected to the reservoir, a manual actuation device for the control input of the pressure regulator, an extension for the fluid connection from the fluid outlet to the release connection of the safety brake.

[0023] The lowering device according to the invention is used as follows: When a lowering operation is necessary, an operator connects the lowering device to the release connection of the safety brake, via the extension of the lowering device. Initially, the operator focuses on creating an energy reserve; he operates the pump to pressurize the fluid in the accumulator until a pressure in the accumulator is obtained corresponding, for example, to the maximum pressure allowed in the hydraulic chamber of the brake or preferably corresponding to the maximum permissible pressure in the accumulator. Secondly, the operator focuses on the actual control; he adjusts the pressure in the hydraulic chamber of the brake as desired by manipulating the manual actuation element of the control input of the three-way pressure regulator, in order to control the descent of the load.

[0024] Thus, the invention is based on the combination of two principles: The decoupling between pressurizing the fluid intended to be injected into the hydraulic chamber for releasing the brake, and the injection of this fluid into said chamber, i.e. the decoupling between the physical action of pumping (which requires power) and the action of adjusting the pressure (which requires finesse, precision, and attention), this decoupling being made possible by the provision of an accumulator in the lowering device; the control of the pressure in the hydraulic chamber of the brake, thanks to the provision of a three-way pressure regulator between this accumulator and the fluid outlet of the lowering device; the lowering is therefore carried out by regulating a pressure and not a volume or a flow rate as is the case with known lowering devices.

[0025] Furthermore, the use of a three-way pressure regulator allows control of the pressure in the hydraulic brake release chamber in both directions: If the setpoint value requested at the control input of the regulator is greater than the regulator's output pressure, i.e., the fluid pressure in the hydraulic chamber for brake release, the pressure regulator connects the fluid inlet and the fluid outlet of the regulator, i.e., respectively, the accumulator and the brake release circuit; the fluid flows towards the brake and the pressure in the hydraulic release chamber increases, which allows the brake to be weakened; if the setpoint value is less than the fluid pressure in the hydraulic chamber for brake release, the regulator connects the fluid outlet of the regulator and the drain, i.e., respectively, the brake and the reservoir;The fluid flows towards the reservoir from the hydraulic release chamber, which strengthens the brake. If the setpoint value is equal to the fluid pressure in the hydraulic release chamber of the brake, the pressure regulator closes the three channels. This corresponds to a stable lowering phase where the braking force is slightly less than the force due to the load.

[0026] Furthermore, once the extension is connected to the brake, the lowering device can be used from the ground, allowing the operator to settle into a stable and comfortable posture, which is not insignificant given that a lowering operation can take several hours depending on the load involved.

[0027] Furthermore, the device according to the invention has the advantage of being compatible with the vast majority of known safety brakes, in particular with all hydraulically actuated safety brakes and with all electromagnetic or electromechanical safety brakes equipped with a hydraulic release option.

[0028] According to particular embodiments of the invention, the lowering device also meets the following characteristics, implemented individually or in any technically possible and operational combination.

[0029] In some embodiments, the lowering device includes a safety stop device, known as a dead man's safety device, comprising a safety lever configured to be able to be moved by an operator between a passive locking position which prohibits the injection of fluid into the hydraulic chamber for releasing the brake and an active unlocking position which permits the injection of fluid into the hydraulic chamber for releasing the brake, the safety lever being automatically returned to its passive locking position in the absence of action by the operator.

[0030] The dead man's safety device ensures a completely safe lowering. At any time, the load can be instantly stopped by releasing the safety lever.

[0031] In some embodiments, the lowering device also includes: a first pressure sensor to measure the fluid pressure at the inlet of the three-way pressure regulator and a first display means associated with said first sensor for displaying the measured pressure, a second pressure sensor to measure the fluid pressure at the fluid outlet of the lowering device or at the outlet of the pressure regulator, and a second display means associated with said second sensor for displaying the measured pressure.

[0032] The first pressure sensor and the first associated display means (audit first sensor) are, for example, a first pressure gauge capable of measuring pressures up to 250 bar, and the second pressure sensor and the second display means (associated with audit second sensor) are, for example, a second pressure gauge capable of measuring pressures up to 150 bar.

[0033] These pressure sensors and associated display devices allow for the monitoring and control of, firstly, the pressure available in the accumulator, which corresponds to the inlet pressure of the pressure regulator, and secondly, the pressure in the hydraulic brake release chamber, which corresponds to the fluid pressure at the device's fluid outlet and preferably also to the outlet pressure of the pressure regulator. The usefulness of these pressure sensors and associated display devices will be better understood after reading the detailed description below.

[0034] In some embodiments, the lowering device includes, in parallel with the pressure regulator, a fluid return circuit between the fluid outlet and the reservoir, allowing the brake release chamber to be emptied into the reservoir. As will be understood later, this return circuit also contributes to the safety of the lowering device and the brake, in combination, respectively, with the deadman's switch and with a pressure limiter (described later).

[0035] In some embodiments, the lowering device includes a mobile trolley on which all the components of the device are mounted. This mobile trolley contributes to the ergonomics of the device according to the invention, in that it allows the operator to easily position themselves in the most suitable location to control the lowering.

[0036] In some embodiments, the pump may be: a hand pump, for example, a piston pump activated manually by a lever; or a motorized pump, for example, a rotary gear pump coupled to a screwdriver, the pump comprising a gear having a recess for receiving a screwdriver bit for the purpose of driving the gear in rotation by the screwdriver. The screwdriver is equipped with a battery so that it can be powered under all circumstances (particularly in the event of a power outage).

[0037] The device may include several pumps, each connected to the reservoir, including, for example, a hand pump and a motorized pump.

[0038] In some embodiments, the lowering device includes: a main bored block to which are connected the tank, the pump, and a pressurizing hose connecting the accumulator to said main bored block, and a secondary bored block to which are connected the pressure regulator, a supply hose connected to the accumulator via the main bored block, a return hose connected to the tank via the main bored block, and the fluid outlet of the lowering device, as well as the first and second pressure sensors when present.

[0039] In some embodiments, the lowering device includes a pressure limiter between the accumulator and the tank, configured to limit the pressure of fluid injected into the accumulator.

[0040] In some embodiments, the return circuit (between the fluid outlet and the reservoir) includes another pressure limiter configured to limit the fluid pressure that is injected via the fluid outlet into the hydraulic brake release chamber.

[0041] In some embodiments, which dead man's device comprises: a first solenoid valve on the return circuit, which first solenoid valve is configured to be open when the safety handle is in the passive locking position and to be closed when the safety handle is in the active unlocking position, and a second solenoid valve at the inlet of the pressure regulator, which second solenoid valve is configured to be closed when the safety handle is in the passive locking position and to be open when the safety handle is in the active unlocking position.

[0042] The invention extends to a method for lowering a load onto a lifting device, characterized in that it uses a lowering device as previously defined, and in that it comprises: a pressurization stage of the accumulator during which at least part of the fluid present in the tank is injected into the accumulator by activation of the pump; a piloting stage of the pressure at the outlet of the pressure regulator using the manual actuation device of the control input of the pressure regulator in order to control the lowering of a load carried by the lifting equipment, the pressurization and piloting stages being carried out successively, independently of each other.

[0043] Preferably, the accumulator is pressurized until it reaches its maximum permissible pressure. During lowering, if necessary—that is, if the pressure at the pressure regulator inlet becomes insufficient—the operator can stop the load's descent by setting the regulator to a sufficiently low pressure to engage the brake, then cease piloting the accumulator to repressurize it using the pump, and finally resume piloting once the accumulator is thus repressurized. Preferably, the operator repressurizes the accumulator until the pressure at the regulator inlet reaches its maximum permissible pressure, in order to avoid frequent repressurization. Brief description of the drawings

[0044] The invention, according to an exemplary embodiment, will be better understood and its advantages will become clearer upon reading the following detailed description, given by way of example and in no way limiting, with reference to the attached drawings in which: [ Fig. 1 ] there figure 1 is a perspective view of a first example of the implementation of a hydraulic lowering device according to the invention; [ Fig. 2 ] there figure 2 represents an example of the implementation of the Fig. 1 , seen from an opposite perspective; Fig. 3 ] there figure 3 is a perspective view of part of a second example of an embodiment of a hydraulic lowering device according to the invention; [ Fig. 4 ] there figure 4 is an exploded perspective view of a third embodiment of a device according to the invention; [ Fig. 5 ] there figure 5 is a hydraulic diagram of the example implementation of the Fig. 4 . Detailed description

[0045] Identical elements represented in the aforementioned figures are identified by identical numerical references.

[0046] THE Fig. 1 And 2 represent a first example of the implementation of a lowering device according to the invention. Reference is also made to figures 4 And 5 for the common parts between this first example of implementation and the third example of implementation which is represented on these Fig. 4 And 5 .

[0047] The lowering device according to the invention of Fig. 1 And 2 understand : a reservoir 1 containing a fluid such as oil, an accumulator 2 capable of withstanding a pressure of 200 bar, for example, a piston pump 3 that can be manually operated by a lever 10, a main drilled block 13 and a secondary drilled block 14 which facilitate the hydraulic connection of some of the elements of the lowering device to each other (see below), a three-way pressure regulator (see Fig. 4 And 5 ), more simply also called a pressure regulator - or even regulator - throughout the description, a flywheel 5 for controlling the pressure at the outlet of the pressure regulator, which corresponds to the pressure of the brake's hydraulic chamber, the shaft 6 of said flywheel (see Fig. 4) being fitted into the control inlet of the pressure regulator. A dead man's safety device comprising in particular a safety lever 7, a clamp-on pressure gauge 8 for measuring and displaying the pressure at the inlet of the pressure regulator 4, a clamp-on pressure gauge 9 for measuring and displaying the pressure at the outlet of the regulator 4, a fluid outlet 18 to which the operator connects the end of a hose (not shown), referred to as an extension, the opposite end of said extension being connected to a fluid inlet connection of the safety brake, a fluid return circuit 30 (see Fig. 5 ) which connects the fluid outlet port 18 to the reservoir 1.

[0048] The second example of implementation illustrated on the Fig. 3 differs from the first example in that its pump is a 3' motorized submersible pump (see Fig. 4 ) including a gear driven by a screwdriver 11.

[0049] The third example illustrated on the Fig. 4 differs from the two previous examples in that it includes two pumps, one of which is a submersible pump 3' driven by a screwdriver 11, similar to the pump in the second example, and a hand pump 3 operated by a lever 10, similar to that in the first embodiment example.

[0050] Reference is now being made to the hydraulic diagram of the Fig. 5 which is valid for all three proposed implementation examples, with the exception of the presence of two pumps which only concerns the third example.

[0051] The sets delimited by dotted lines represent respectively reservoir 1, main drilled block 13 and secondary drilled block 14.

[0052] Pumps 3 and 3' are connected on one side to reservoir 1 and on the other side to the main bored block 13; they allow the fluid present in reservoir 1 to be injected into accumulator 2 via the main bored block 13, to which accumulator 2 is connected by a first flexible hose 15, called pressurization hose, and via check valves 20 (for hand pump 3) and 21 (for gear pump 3').

[0053] A pressure limiter 22, also mounted on the main drilled block 13, prevents the accumulator from being inflated beyond its maximum permissible pressure by returning the pumped fluid to the reservoir 1 when this pressure is reached.

[0054] In addition, as is customary, tank 1 is equipped with a level detector 12.

[0055] A second flexible hose 16, called the supply hose, extending between the main drilled block 13 and the secondary drilled block 14 allows the accumulator 2 to be connected to the fluid inlet of the pressure regulator 4.

[0056] The clamp-on pressure gauge 8 measures and displays the pressure P1, which corresponds to both the fluid pressure in the accumulator 2 and the fluid pressure at the inlet of the pressure regulator 4. The clamp-on pressure gauge 9 measures and displays the pressure P2, which corresponds to both the pressure at the outlet of the pressure regulator 4, the pressure at the fluid outlet 18 of the lowering device and the pressure in the hydraulic brake release chamber.

[0057] When the operator increases the setpoint pressure at the control input of the pressure regulator using the handwheel 5, the pressure P2 at the output of the regulator increases accordingly and the fluid is injected into the hydraulic brake release chamber via the extension.

[0058] When the operator actuates the handwheel 5 to decrease the set pressure, the outlet pressure P2 decreases and the fluid flows in the opposite direction, from the brake to the lowering device. The fluid is then returned to the reservoir 1 via the return circuit 30, and in particular via a conduit 26, provided in the secondary drilled block 14, and then via a third hose 17, called the return hose, extending between the secondary drilled block 14 and the main drilled block 13.

[0059] Optionally, but advantageously, a pressure relief valve 27 is provided on the return line 26 to protect the brake. If, through carelessness or error, the operator sets a pressure at the control input of the pressure regulator 4 that exceeds the pressure withstanding the hydraulic chamber for releasing the brake, the pressure relief valve 27 opens and some of the fluid is directed to the reservoir instead of being sent to the brake.

[0060] The presence of this pressure limiter 27 allows the lowering device to be used safely for all types of brakes, not only for brakes whose hydraulic release chamber can withstand up to 180 bar (such as a safety brake for a lifting machine capable of lifting several tens, or even hundreds, of tons), but also for lower-power brakes whose hydraulic release chamber is limited to 20 bar, for example. In the absence of such a pressure limiter 27, one way to reduce the risk of brake damage is to limit the pressure P1 to which the accumulator is initially pressurized, by stopping the accumulator pressurization step when the pressure P1 approaches the maximum pressure that the brake's hydraulic release chamber can withstand (which is a known technical specification of the brake).

[0061] The dead man's device includes a safety solenoid valve 25 on the fluid return circuit 30. The solenoid valve 25 is actuated by a progressive stop 24 (see Fig. 4 ) pressed by the safety lever 7. When the operator presses the safety lever 7, the safety solenoid valve 25 is closed and the pressure at the outlet of the regulator 4 is sent into the brake, or possibly into the return line 26 if the maximum pressure supported by the brake is exceeded.

[0062] Releasing the safety lever 7 causes the progressive stop 24 to return, the solenoid valve 25 to open and the circuit at the outlet of the pressure regulator (including the hydraulic chamber for releasing the brake) to drain into the reservoir 1, which causes the brake to close immediately.

[0063] In addition to the solenoid valve 25, a second solenoid valve 23 may be provided in the secondary drilled block 14 at the inlet of the pressure regulator 4. This second solenoid valve 23 is actuated, in the closing direction, by a second progressive stop 24 which is depressed when the operator presses the safety lever 7.

[0064] Releasing the safety lever 7 in this case therefore causes not only the opening of solenoid valve 25, but also the closing of solenoid valve 23, which consequently isolates the accumulator 2 from the rest of the circuit. Solenoid valve 23 is optional; it complements solenoid valve 25 to ensure very rapid brake closure, avoiding the simultaneous emptying and filling of the brake release hydraulic chamber. Solenoid valve 23 thus reduces the brake's return time.

[0065] The illustrated deadman's safety device (with its lever 7, two solenoid valves, and two progressive stops) is described only as a non-limiting example. A person skilled in the art is generally capable of designing a deadman's safety device using their general knowledge. As an alternative, one could consider a safety device controlled by a customer-supplied detection system such as overspeed, overheating, or a timer. This alternative is less advantageous because it requires the device to be equipped with a battery to power the detection components in the event of a power failure.

[0066] In the example illustrated in the Fig. 5 A flow restrictor 37 is also provided between the accumulator and the reservoir. This restrictor is used in ON / OFF mode like a valve, to allow drainage (in the ON position) from the accumulator 2 to the reservoir 1 for the purpose of disengaging the lowering device.

[0067] In the lowering process according to the invention, the operator first creates an energy reserve by fully inflating the accumulator using pump 3 or pump 3'. This operation can be repeated as many times as necessary during the lowering process, taking care first to block the charge by reducing the setpoint value at the control input of the pressure regulator.

[0068] He then operates the handwheel 5 to increase the pressure in the brake, more or less rapidly, until the load is released. This means that he has exceeded the equilibrium pressure in the brake. This equilibrium pressure depends not only on the brake but also, and especially, on the load (it is not a technical specification of the brake alone); it is therefore unknown to the operator at the start of the lowering process.

[0069] The pressure gauge 9 allows the operator to determine the equilibrium pressure at the moment the load begins to descend abruptly. The operator then sharply turns the handwheel in the opposite direction to close the brake and stop the load. Now that the operator has an approximate idea of ​​the equilibrium pressure, they can more precisely control the handwheel to quickly return to this pressure and then gradually exceed it to slide the load. The operator can then easily control the load's descent speed by precisely adjusting the pressure regulator 4 around the equilibrium pressure.

[0070] However, a lowering device without a pressure gauge 9 conforms to the invention. The operator must then control the regulator blindly, without ever knowing the equilibrium pressure value. While not essential, the pressure gauge 9 helps reduce operator stress.

[0071] The pressure gauge 8 allows the operator to monitor the energy reserve in the accumulator 2. This enables them to anticipate a potential pressure drop and the need to repressurize the accumulator. The pressure gauge 8 is an optional component of the lowering device according to the invention, as it is not essential for operator safety or successful lowering (a pressure drop at the regulator inlet would result in the brake closing and the load stopping). Like the pressure gauge 9, the pressure gauge 8 contributes to the ergonomics of the lowering device and helps reduce operator stress.

[0072] In addition to pressure gauges 8 and 9, the lowering device illustrated on the Fig. 5 includes two other pressure ports, namely: a pressure sensor 28 at the main drilled block 13 configured to measure pressure P1; this sensor 28 theoretically indicates the same measurement as the pressure gauge 8, i.e. the pressure P1 delivered by the accumulator, a pressure sensor 29 on the return circuit between the fluid outlet 18 and the pressure limiter 27; this sensor 29 theoretically indicates the same pressure as the pressure gauge 9, i.e. the pressure delivered by the pressure regulator 4 which also corresponds to the pressure in the hydraulic brake release chamber.

[0073] These additional sensors can be connected to a recording device or a remote control device, for retrospective or remote analysis of the lowering operation.

[0074] The lowering device according to the invention preferably includes a rolling trolley 31 which, in the illustrated examples, includes, among other things, wheels 35, two side plates 32, 33 connected in particular by a lower plate 36 and by an upper plate 34 on which are mounted the collar gauges 8 and 9 and the safety handle 7.

Claims

1. Hydraulic lowering device for a safety brake of a lifting machine, for use with a brake provided with a hydraulic release chamber and a fluid inlet connection, referred to as a release connection, the lowering device comprising: - a fluid reservoir (1), and - a fluid outlet port (18), characterised in that it comprises: - a pressurised fluid accumulator (2), connected to the fluid reservoir (1), - a pump (3, 3') connected to the reservoir for injecting the fluid present in the reservoir under pressure into the accumulator, - a three-way pressure regulator (4) comprising a mechanical control inlet for adjusting a setpoint value, a fluid inlet connected to the accumulator (2), a first fluid outlet connected to the fluid outlet port (18) of the lowering device, and a second, so-called drain, fluid outlet connected to the reservoir (1), - a member (5) for manually actuating the mechanical control inlet of the pressure regulator (4) by an operator, - an extension for the fluid communication of the fluid outlet port (18) with the release connection of the safety brake.

2. Lowering device according to claim 1, comprising a safety stop device, so-called dead man safety device, comprising a safety handle (7) configured to be able to be moved by an operator between a passive locking position that prohibits fluid injection into the brake hydraulic release chamber and an active unlocking position that authorises fluid injection into the brake hydraulic release chamber, the safety handle (7) being automatically returned to its passive locking position in the absence of action by the operator.

3. Lowering device according to any one of claims 1 or 2, comprising: - a first pressure sensor (8) for measuring pressure of the fluid at the inlet of the pressure regulator (4) and a first display means (8) associated with said first sensor for displaying the pressure measured, - a second pressure sensor (9) for measuring pressure of the fluid at the fluid outlet port of the lowering device or at the outlet of the pressure regulator and a second display means (9) associated with said second sensor for displaying the pressure measured.

4. Lowering device according to claim 3, wherein the first pressure sensor and the first display means are a first pressure gauge (8) capable of measuring pressures up to 250bar, and the second pressure sensor and the second display means are a second pressure gauge (9) capable of measuring pressures up to 150bar.

5. Lowering device according to any one of claims 1 to 4, comprising a fluid return circuit (30) between the fluid outlet port (18) and the reservoir (1) in parallel with the pressure regulator (4).

6. Lowering device according to any one of claims 1 to 5, comprising a movable carriage (31) on which all components of the lowering device are mounted.

7. Lowering device according to one of claims 1 to 6, the pump being chosen from: a piston pump (3) manually activated by a lever (10), a rotary gear pump (3') associated with a screwing machine (11).

8. Lowering device according to any one of claims 1 to 7, comprising: - a main bored block (13) to which the reservoir (1), the pump (3), a pressurising hose (15) connecting the accumulator (2) to said primary bored block are connected, and - a secondary bored block (14) to which the pressure regulator (4), a supply hose (16) connected to the accumulator via the main bored block (13), a return hose (17) connected to the reservoir (1) via the main bored block (13), and the fluid outlet port (18) of the lowering device are connected.

9. Lowering device according to any one of claims 1 to 8, comprising a pressure limiter (22) between the accumulator (2) and the reservoir (1), configured to limit the fluid pressure injected into the accumulator.

10. Lowering device according to claim 5, wherein the return circuit (30) comprises another pressure limiter (27) configured to limit the fluid pressure injected into the brake hydraulic release chamber via the fluid outlet port (18).

11. Lowering device according to any one of claims 1 to 10, wherein the dead man device comprises: - a first solenoid valve (25) on the return circuit (30), which first solenoid valve is configured to be open when the safety handle (7) is in the passive locking position and to be closed when the safety handle is in the active unlocking position, and - a second solenoid valve (23) at the inlet of the pressure regulator (4), which second solenoid valve is configured to be closed when the safety handle (7) is in the passive locking position and to be open when the safety handle is in the active unlocking position.

12. Method for lowering a load on a lifting device, characterised in that it uses a lowering device according to one of the preceding claims, and in that it comprises: - a step of pressurising the accumulator (2) during which at least part of the fluid present in the reservoir (1) is injected into the accumulator (2) by activating the pump (3, 3'), - a step of governing the pressure at the outlet of the pressure regulator (4) using the member (5) for manually actuating the control inlet of the pressure regulator so as to control lowering of a load carried by the lifting device, - the pressurisation and governing steps being executed successively, independently of one another.