ELEVATOR TRACTION DEVICE

This application claims the benefit of European Patent Application EP19382162.6 filed March 5, 2019.

The present disclosure relates to methods for determining a malfunction of a centrifugal brake mounted on a traction device of an elevator system. BACKGROUND

Modern wind turbines are commonly used to supply electricity into the electrical grid. Wind turbines generally comprise a rotor mounted on top of a wind turbine tower, the rotor having a rotor hub and a plurality of blades. The rotor is set into rotation under the influence of the wind on the blades. The operation of the generator produces the electricity to be supplied into the electrical grid.

When maintenance is required inside wind turbines, hoists are often used in the form of elevator-like structures where a lift platform or a cabin for the transportation of people and/or equipment is hoisted up and/or down within the wind turbine tower. Wind turbines are often provided with working platforms arranged at various heights along the height of the tower with the purpose of allowing workers to leave the cabin and inspect or repair equipment where intended. Elevator systems (or “service lifts”), in general, include an elevator car being suspended within a hoistway or elevator path by wire ropes. The term wire rope is herein used to denote a relatively thick cable. But in the art, the terms cables and wire ropes are often used interchangeably. In some systems, e.g. for some electric elevators, a counterweight may be provided depending on e.g. the available space. Other systems such as hydraulic elevators normally do not comprise a counterweight.

The service elevators may incorporate some form of traction device mounted on or attached to the elevator. The traction device may comprise a housing including a traction mechanism, e.g. a motor driven traction sheave. The motor typically may be an electrical motor, although in principle other motors could be used.

Service elevators further may incorporate an electromagnetic brake. Additionally, the service elevators may incorporate a centrifugal brake forming part of the traction device. In this respect, when e.g. a speed of the service elevators is above a first speed threshold, the centrifugal brake of the traction device may be operated as an emergency stop device to mechanically slow down the service elevator in case it is falling.

In addition to the above-commented brakes, a“secondary safety device" or“fall arrest device" may be mounted on or attached to the elevator. Such a fall arrest device serves as a back-up for the main electromagnetic brake (and the centrifugal brake of the traction device) and may typically incorporate some form of sensing mechanism sensing the elevator’s speed. The secondary safety device may automatically block the elevator and inhibit any further movement if the elevator moves too fast, i.e. when the elevator might be falling. The speed detection mechanism in this sense acts as an overspeed detector.

A hoisting wire rope of the service elevator or a dedicated safety wire rope may pass through an entry hole in the safety device, through the interior of the safety device and exit the safety device through an exit hole at an opposite end. Some form of clamping/locking mechanism for clamping or otherwise locking or blocking the hoisting wire rope or the safety wire rope when an unsafe condition exists (i.e. when the overspeed detector trips) may be incorporated in the safety device.

Such an overspeed detector may comprise a driven roller coupled with movable parts that are forced outwardly as the roller rotates when it is driven by the wire rope passing along it. A pressure roller ensures the contact between the wire rope and the driven roller of the centrifugal overspeed detector. If the wire rope passes through the safety device too rapidly, the brake trips and the jaws clamp onto the wire, thus blocking the safety device on the wire rope.

With respect to the centrifugal brake of the elevator’s traction device, if this device is not periodically inspected and maintained, contamination and wear can affect the ability of this centrifugal device to mechanically slow down the elevator e.g. in an emergency situation. In this respect, the centrifugal brake of the traction device may typically be mounted inside the housing of such a traction device. Thus, in order to inspect and maintain the centrifugal brake by e.g. maintenance personnel, the elevator’s traction device may be periodically disassembled such that access is provided to the centrifugal brake. In summary, the inspection and maintenance of the centrifugal brake of the elevator’s traction device brake can be time-consuming and it may be a cumbersome task to carry out.

US 2018/237262 discloses a method for inspecting a cable mounted device for an elevator.

US 2015/259174 discloses a method and arrangement for detecting a working condition of a mechanical brake of vertical transport equipment, the vertical transport equipment including a frequency converter, an electrical motor and a mechanical brake.

WO 2018/024694 discloses a fall arrest device comprising a casing with an entry hole for the wire rope, an exit hole for the wire rope, a clamping mechanism and an overspeed detector arranged inside the casing.

Examples of the present disclosure seek to at least partially reduce one or more of the aforementioned problems.

SUMMARY

According to a first aspect, a method for determining a malfunction of a centrifugal brake of a traction device mounted on an elevator cabin is provided. The method comprises: releasing the elevator cabin such that the elevator cabin descends along an elevator path. The method further comprises detecting the speed of the elevator cabin with a wire rope mounted device arranged on the elevator cabin and around a wire rope, comparing the detected speed of the elevator cabin with a first threshold speed, and determining the malfunction of the centrifugal brake if the detected speed of the elevator is above the first threshold speed.

According to this first aspect, a method adapted to check the proper functioning of the centrifugal brake of an elevator system’s traction device by comparing the detected speed of the elevator cabin with the first threshold speed of the centrifugal brake is readily provided to an operator or maintenance personnel.

The elevator cabin may be released such that the elevator cabin descends along an elevator path. As the cabin descends, the descent speed of the cabin is increased. The speed would normally have to be controlled and limited by the centrifugal brake of the traction device of the elevator cabin, if the centrifugal brake functions properly. The descent speed is detected using a device mounted in the elevator cabin and around a wire. Such an operation can be performed without the need of further expensive devices and can be very reliable since it is directly linked with the movement of the elevator cabin along the wire rope.

The detected descent speed of the cabin is compared with the first threshold speed to which the centrifugal brake is configured to brake the elevator cabin. In this respect, if the descent speed of the cabin is above the first threshold speed of the centrifugal brake, a malfunction of the centrifugal brake is determined. Proper functioning of the centrifugal brake mounted on traction device of the elevator system can thus be checked by an operator or maintenance personnel using a simple, reliable and easy-to-use method. There is no need to open the traction device, dismount it or otherwise internally inspect the device. All such inspection devices can by themselves introduce failure modes.

In examples, the cable mounted device is a fall arrest device including an overspeed detector. The overspeed detector comprises a casing with an entry hole for the wire rope, and an exit hole for the wire rope, a clamping mechanism, and a driven roller arranged to be driven by the wire rope and wherein the clamping mechanism is configured to clamp the wire rope if the overspeed detector detects a speed of the driven roller above a second predetermined threshold, and wherein detecting the speed of the elevator cabin comprises obtaining the speed of the driven roller, and deriving the speed of the elevator cabin based on the obtained speed of the driven roller.

The driven roller may be directly driven by the wire rope, i.e. be in direct contact with the wire rope. The driven roller may also be indirectly driven by the wire rope. I.e. a driven roller is operatively coupled to an element (e.g. a roller) that is directly driven by the wire rope.

In some other examples, obtaining the speed of the driven roller comprises detecting selected areas of the driven roller during a period of time using a sensor and obtaining the speed of the driven roller based on the detected areas.

The driven roller has one or more selected areas to be detected by e.g. a sensor inside the casing. As the driven roller rotates, the selected areas are repeatedly sensed by the sensor during a period of time. A signal corresponding to the sensed selected areas may be processed and the speed of the driven roller may be obtained. The speed of the driven roller may thus be easily obtained using a sensor which already forms part of the design of the fall-arrest device.

The (indirectly) driven roller may form part of a centrifugal brake.

In examples, the wire rope mounted device is the traction device, and wherein the traction device comprises a motor for driving the traction, and wherein detecting the speed of the elevator cabin comprises determining electrical currents generated in the motor and determining the speed of the elevator cabin based on the determined currents generated by the motor. Electrical currents may be understood as covering any form of electromotive force (voltages, currents) generated when the motor is forced to rotate.

When the elevator is released, the weight of elevator cabin is sufficient to back-drive electric motor via the sheave. In this case, the electric motor acts as a generator and currents may be caused to flow in the generator. The currents may be processed and a corresponding descent speed of the elevator cabin may be obtained based on the measured currents. It noted that the motor is a device which already forms part of the traction device of the elevator system. The need of further devices to detect the descent speed of the elevator cabin is thus avoided.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting examples of the present disclosure will be described in the following, with reference to the appended drawings, in which:

Figure 1 is a perspective view of an example of a fall-arrest device;

Figures 2a - 2c show longitudinal cross-sectional views and a cross-sectional top view of a fall arrest device which may the same or similar to the fall-arrest device shown in figure 1 ;

Figures 3a - 3c schematically illustrate an example of a fall arrest device including an additional sensing mechanism and a motion indicator; Figure 4 schematically illustrates a cross-sectional view of an example of a traction mechanism of an elevator system; Figure 5 schematically illustrates an example of a centrifugal brake forming part of the traction mechanism which may be the same or similar to the one shown in figure 4;

Figure 6 is a flow diagram of a method for determining a malfunction of a centrifugal brake, which maybe the same or similar to the one shown in figure 5, mounted on a traction device of an elevator system.

DETAILED DESCRIPTION OF EXAMPLES In these figures the same reference signs have been used to designate matching elements.

Figure 1 schematically illustrates a fall arrest device. The fall arrest device 10 of figure 1 is mounted on an elevator (not shown), and the fall arrest device comprises a housing 13 having an upper wire rope entry 12, an unlocking lever 4 and an inspection window 51. The housing further comprises a lower wire rope exit 14. Also indicated in figure 1 is an emergency locking lever 38. The wire rope 5 passes through the fall arrest device 10. Figures 2a - 2c schematically illustrate cross-sectional views of a safety device 10 similar to the one shown in figure 1. In the interior of the housing of the safety device 10, at least one safety mechanism is provided. The safety mechanism acts on the wire rope. Figure 2b illustrates an entry hole 12 for a wire rope. The wire rope passes in between the clamping jaws 8, 9 of upper clamp 6 and lower clamp 7. In normal operation, the clamping jaws are “open”, and there is substantially no contact between the wire rope and the clamping jaws. The jaws are in normal operation prevented from closing by blocking element 59. If in operation, an overspeed of the wire rope is detected (this indicates that the elevator to which the safety device is mounted is falling), the overspeed detector trips which moves the blocking element 59 and allows the jaws 6, 7 to close. The elevator is thus prevented from falling. The overspeed detection and trip mechanism may comprise a first driven roller 48 which is in contact with the wire rope. As the wire rope moves, the roller 48 is driven and rotates. The first driven roller 48 is operatively coupled with the driven roller of the centrifugal overspeed detector 55 shown in figure 2a. Both the driven roller 48 and the driven roller of the overspeed detector 55 may be mounted on the same axle or shaft.

The overspeed detector 55 may comprise a plurality of weights 53, which are configured to move outwards as the detector rotates due to the centrifugal forces acting on them. If the driven roller rotates too fast (i.e. this may indicate an unsafe condition caused by e.g. a traction hoist malfunction and/or electromagnetic brake malfunction), the weights 53 move outwardly to such an extent that the detector trips: the weights contact lever 57, which releases the blocking element 59 from its original position. When the detector trips, as explained before, the clamping jaws close down and the elevator comes to a halt.

In order to ensure that the first driven roller 48 is in fact driven by the movement of the wire rope, a pressure roller 50 may force both of them in contact with each other. Reference sign 49 indicates the space between the first driven roller 48 and the pressure roller 50 through which the wire rope passes. Both the pressure roller 50 and the driven roller 48 are constantly in contact with the tensioned wire rope.

Figures 3a - 3c show schematic views inside the casing of a fall arrest device such as the one described with reference to figure 1 and figures 2a - 2c. Even though in the following, reference will be made to such a fall arrest device, it should be clear that a similar teaching may be applied to different kinds of fall arrest devices: e.g. the clamping mechanism may be different from the one described before, and the overspeed detector may be different. The overspeed detector might be a centrifugal overspeed detector, but does not necessarily need to be of this type. If there is a centrifugal brake, it might have the aforementioned arrangement of pressure rollers and driven rollers, but this is merely one possibility.

The wire rope, either directly or indirectly, drives the driven roller of the centrifugal overspeed detector. In this example, a photocell detector 66 is used. The photocell detector 66 according to this example has a light transmitter, and a light receiver. Selected parts 58 of e.g. the perimeter of the driven roller of the centrifugal overspeed detector 55 or of the centrifugal elements 53 may be made to be reflective using a foil or paint, or other. Alternatively, selected parts of the driven roller of the centrifugal overspeed detector may be made to be non-reflective.

As a result, selected parts 58 of the driven roller of the centrifugal overspeed detector will reflect light received from the transmitter to the receiver, whereas other parts of the driven roller will not reflect the light. As the driven roller rotates, it continuously receives alternating signals of light, and no light, or“ reflective” and“non-reflective".

In some examples, the photocell detector 66 may include a dedicated controller. The controller may receive the above-commented signals of light, and no light, or “ reflective” and“non-reflective". The converter controller may include one or more processor(s) and associated memory device(s) configured to perform a variety of computer-implemented functions (e.g., performing the calculations and the like and storing relevant data as disclosed herein) according to any of the methods herein described. The controller may also include a communications module. Further, the communications module may include a sensor interface (e.g. one or more analog-to- digital converters) to permit signals received from the photocell detector 66 to be converted into signals that can be understood and processed by the processor(s). It should be appreciated that the photocell detector 66 may be communicatively coupled to the communications module using any suitable means as for example a wired connection or a wireless connection. As such, the controller (and thus the processor) may be configured to receive one or more signals from the sensors.

According to this example, the controller may perform various different functions, such as receiving the signals detected by the photocell detector 66 during a period of time and obtaining the (rotational) speed of the driven roller of the overspeed detector based on the signals detected during such period of time. In this respect, the number of rotations of the driven roller of the overspeed detector may be determined for a time period (e.g., rotations per minute) to obtain the speed of the driven roller.

Following the example, when e.g. an elevator cabin starts to descend along an elevator path in case of a“no power” descent, the measurements by the photocell detector 66 may start immediately. The controller may count the number of rotations indicated by the signals from the photocell detector 66. Additionally, the controller may include a clock mechanism so as to determine the cumulative number of rotations within a period of time i.e. the rotation speed of the driven roller of the centrifugal overspeed detector 55. The information of the rotation speed may typically be formatted as rotations per minute (RPM). The controller may further perform the function to derive a (linear) speed of the elevator cabin based on the obtained speed of the overspeed detector.

Thus, if e.g. the elevator cabin is released, the descent speed of the elevator cabin along the elevator path may easily be detected by sensing the rotation of the driven roller 55 of the fall-arrest device using the photocell detector 66 which typically forms part of the design of the fall arrest device. The need of extra devices to detect the speed of the elevator cabin is thus avoided. In this respect, the obtained speed of the elevator cabin may be used to detect a malfunction of the centrifugal brake depicted in figure 5 forming part of a traction device, as will be explained later on. It should be clear that the arrangement with a (photocell) detector could be adapted to different fall-arrest mechanisms.

In examples, the photocell detector 66 is connected to a connector 60 through an electric, data or fiber cable 63. In examples, the connector 60 may be connected to an indicator, such as e.g. a light, in particular a LED. This light may be mounted on the outside of casing 13 of the safety device but may also be installed in a suitable location on the elevator. In a further example, it may also be located remotely in a position in which it is visible to operating personnel. In one example, the indicator may be mounted to an inside wall of a wind turbine tower.

The detector 66 thus selectively turns the indicator on and off repeatedly. As commented above, such a transmission of the alternating signals may be through an electric, data or fiber cable 63 or may be wireless.

Furthermore, in this particular example, reference was made to a photocell detector based on the presence or absence of reflection, but alternative sensors might be used. In another example, sensors suitable for determining the colour of a surface may be used. The centrifugal elements may then be distinguished from other parts of the driven roller based on their colour. One other example of a sensor that may be used is an inductive sensor. Selected portions or areas of the driven roller or centrifugal elements may be made from a different material. The inductive sensor may thus again receive alternating signals, “material A”,“material B”, or simply“positive” and“negative”. Each of these examples of sensors take up little space in a fall arrest device and make retrofitting existing fall arrest devices with the additional described capability possible. Depending on the type of sensor used, existing fall arrest devices may be simply retrofitted by installing the sensor and connecting the indicator with the sensor.

In other cases, specific portions or areas of the driven roller of the overspeed detector (forming part of the fall arrest device) are made detectable, and/or others non- detectable. A suitable sensor inside the casing and a motion indicator giving indications that are visible or hearable from the outside of the casing may be easily incorporated. In other examples, the driven roller that is detected could be a directly driven roller,

In any case, with alternative suitable sensors used to detect portions of the roller 55, the speed of the roller and the derived speed of the elevator cabin based on the detected speed of the roller may be calculated in a substantially similar manner as hereinbefore described. The obtained speed of the elevator cabin will be used to detect a malfunction of the traction mechanism’s centrifugal brake as will be described later on.

Figure 4 schematically illustrates a cross-sectional view of an example of a traction mechanism of an elevator system. Particularly, figure 4 illustrates a cross-sectional view of a traction hoist 80 for an elevator cabin i.e. the traction mechanism may be mounted in the elevator cabin. Reference sign 81 indicates an entry hole for a cable.

The cable in this example passes completely around the traction sheave 70 and then exits the traction hoist at the bottom of the housing. The cable guide 72 and pressure rollers 74 and 76 ensure that the cable maintains contact with the traction sheave along the entire perimeter of the traction sheave 70. Also shown in figure 4 is an overload detector 78.

An electric motor may drive the traction sheave 70 through a gear system involving one or more stages. As the sheave is rotated, it“ climbs” or descends the cable. The elevator cabin (not shown) thus moves upwards or downwards. The traction mechanism may further comprise a centrifugal brake 150 as shown in figure 5. The cable which passes around the traction sheave may drive and rotate the rollers 74 and 76. Particularly, the traction sheave 70 may be operatively coupled with a driven roller 151 of the centrifugal brake 150. Both the traction sheave 70 (see figure 4) and the driven roller 151 of the centrifugal brake 150 (see figure 5) may be mounted on the same axle or shaft.

The driven roller 151 of the centrifugal brake in this example further comprise brake shoes 152a, 152b configured to move outwards as the driven roller 151 rotates due to centrifugal forces acting on them. In some examples, the brake shoes 152a, 152b may carry a pad (not shown) of composite brake liner or other suitable material on its outer surface. Throughout the present description and claims the term “shoe" or “brake shoe is used to describe a moveable element or assembly that presents a braking surface, and may be configured to brake or slow down the driven roller 151 forming part of the centrifugal brake 150.

In a first“armed” position shown in figure 5, the shoes 152a, 152b are connected to each other using springs 153a, 153b. Springs of all different characteristics and sizes are readily available and easily mountable. In this “armed’ position there is substantially no contact between the shoe 152a, 152b and corresponding braking surfaces (not shown). However, as the driven roller 151 is rotated at an increasing speed, the force on the springs 153a, 153b increases, due to the centripetal acceleration of the brake shoe 152a, 152b. At the desired threshold (or “engagement’) speed of the brake shoes 152a, 152b, the shoes 152a, 152b may be forced outwards, into an“engaged’ position (not shown). It is noted that threshold speed at which the centrifugal brake is activated may be below the threshold speed at which the fall-arrest device described in figures 2 and 3a - 3b is activated. In this“engaged position", the shoes 152a, 152b (or shoe pads if present), may contact a corresponding non-rotating part e.g. a housing of the electric motor driving the traction sheave 70 and it may slow down the driven roller 151 (and thus the elevator cabin indirectly coupled to the driven roller 151 via the sheave and the cable) by mechanical friction. The centrifugal brake 150 may remain in the “engaged’ configuration until the rotating roller 151 is rotated at a decreasing speed. As the roller 151 is rotated at a decreasing speed, the force acting on the springs 153a, 153b decreases and the shoes 152a, 152b are forced back into the“armed’ position shown in figure 5 i.e. the position in which there is substantially no contact between the shoes 152a, 152b and the corresponding braking surfaces (not shown).

The desired or selected engagement or deployment speed may be modified in several ways. For example, the shoes 152a, 152b may be more heavily spring loaded by increasing the spring constant of the corresponding springs 153a, 153b to increase the rotational speed of engagement i.e. the threshold speed at which the centrifugal brake will at least partially brake the elevator cabin. The engagement speed may also be increased by reducing the weight of the shoes 152a, 152b. In any event, the force on the corresponding spring 153a, 153b due to the centripetal acceleration should be sufficient to provide adequate force on the shoe 152a, 152b in order to slow down the roller 151 (and thus the elevator cabin indirectly connected to such roller) when shoes 152a, 152b engage the corresponding braking surface.

In any case, the repeated contact between the shoes 152a, 152b and the corresponding braking surface may result in a malfunction e.g. wear of the shoes 152a, 152b and / or the braking surface. As a result of wear, the shoes may not properly contact the braking surface. This situation may be dangerous since it may compromise the correct functioning of the centrifugal brake (and thus the proper brake of the elevator cabin at a speed of the elevator cabin above a first threshold speed e.g. in an emergency situation).

Following the example, in order to detect the above-commented wear of the shoes 152a, 152b and / or the braking surface, the electromagnetic brake of the elevator cabin (not shown) may be released in a so-called“no power” descent such that the elevator cabin descends along the corresponding elevator cabin path. Then, the descent speed of the elevator cabin may be determined. This can be performed in at least two alternative ways:

In an example, the speed of (one of) the roller(s) of the fall-arrest device may be detected and the (descent) speed of the elevator cabin may be derived from the speed of the roller of the fall arrest device as hereinbefore described with reference to figures 3a - 3c.

In a further example, as shown in figure 4, an electric motor may drive the traction sheave 70 through a gear system involving one or more stages. In this example, instead of obtaining the elevator cabin speed by detecting the rotation of a roller forming part of the fall arrest device, the speed of the elevator cabin may be obtained by sensing electrical currents generated in the electric motor (of the traction device) during a“no power” descent. In this case, the motor acts as a generator.

Once the elevator cabin is released, friction between the wire and the sheave causes the electric motor to rotate via the gearbox. As such, the electric motor will act as an electric generator resulting in electrical currents at the motor terminals. In such a descent, a voltage generated in the motor (terminals) may be proportional to the speed of the elevator cabin.

The electrical power generated by the motor may be supplied to a further dedicated processor. The electrical power supplied to the processor may correspond to a suitable signal maintained to suitable levels according to the operating needs of the dedicated controller using e.g. an AC-DC converter.

According to this example, the controller may perform various different functions, such as receiving the signal corresponding to the determined electrical power generated by the motor and obtaining a descent speed of the elevator cabin based on the detected signal.

In any event, once the descent speed of the elevator cabin is obtained, the obtained speed of the cabin is compared with a threshold speed of the centrifugal brake 150 i.e. the speed at which the shoes 152a, 152b are forced outwards, into an“engaged’ position, in order to slow down the roller 151 (and thus the elevator cabin indirectly connected to such roller) as shown in figure 5. This may be performed with any of the controllers described herein or with a further dedicated controller.

If the detected speed of the elevator cabin is above the threshold speed of the centrifugal brake 150 to which the centrifugal brake is expected to brake the descent of the elevator cabin, this means that the centrifugal brake is not functioning properly. The detection of the malfunction of the centrifugal brake is thus performed without the need to dismantle the traction device to physically check whether there is wear or not in the traction device’s centrifugal brake.

Moreover, a warning element may be activated for generating an audible warning or a visual warning when the malfunction of the centrifugal brake is determined. Figure 6 is a flow diagram of an example of a method for determining a malfunction of a centrifugal brake mounted on traction device of an elevator system.

At block 90, an elevator cabin of the elevator system forming part of an elevator system is provided. The elevator cabin is configured to run along an elevator path. Moreover, a centrifugal brake configured to control the descent speed of the elevator cabin to a first threshold speed may also be provided. The centrifugal brake may be the same or similar as the one depicted in figure 5.

At block 91 , the elevator cabin may be released such that elevator cabin descends along the elevator path. Typically, when an electric motor is unpowered, a brake (e.g. an electromagnetic brake) is engaged to prevent rotation of the electric motor thereby preventing motion of elevator cabin. However, in this case, the brake of the traction device may be manually released.

In theory, as the speed of descent increases and it is situated above a threshold speed, the braking effect of the traction device’s centrifugal brake increases resulting in a stable, safe and limited descent speed. However, as previously commented, contamination and wear can affect the ability of the traction device’s centrifugal brake to mechanically stop the elevator cabin e.g. in an emergency situation.

At block 92, the speed of the elevator is detected with a device mounted in the elevator cabin and around a wire of the elevator system while the elevator cabin descends along the elevator path.

In examples, the speed of the elevator cabin is derived from the detected speed of a roller forming part of the fall-arrest device as hereinbefore described with reference to figures 3a - 3c.

However, in some other examples as hereinbefore described, an electric motor of a traction device may be used to measure or estimate the descent speed. The motor acts as a generator and outputs power. A descent speed of the elevator cabin may be derived based on the generated electrical power.

At block 93, the speed of the elevator cabin is being detected using any of the methods as described herein. The (descent) speed of the elevator cabin is compared with the threshold speed of the traction device’s centrifugal brake at which such centrifugal brake must be activated.

At block 94, if it is detected that the (descent) speed of the cabin is above the threshold speed at which the centrifugal brake must be activated, it is determined that the centrifugal brake is not in a proper condition and wear is affecting the ability to brake the elevator’s cabin. Suitable maintenance, inspection for wear or even the change of the centrifugal brake may thus be performed.

Although only a number of examples have been disclosed herein, other alternatives, modifications, uses and/or equivalents thereof are possible. Furthermore, all possible combinations of the described examples are also covered. Thus, the scope of the present disclosure should not be limited by particular examples, but should be determined only by a fair reading of the claims that follow.