WO2017129852A1

WO2017129852A1 - Arrangement for tensioning a traction member of an elevator and for monitoring the tension of the traction member

Info

Publication number: WO2017129852A1
Application number: PCT/FI2016/050036
Authority: WO
Inventors: Markku Haapaniemi; Matti RÄSÄNEN; Janne Mikkonen; Esko Aulanko; Jorma Mustalahti
Original assignee: Kone Corporation
Priority date: 2016-01-25
Filing date: 2016-01-25
Publication date: 2017-08-03

Abstract

The invention relates to an arrangement for tensioning a traction member of an elevator and for monitoring the traction member. The elevator comprises at least an elevator car (1) arranged to run in an elevator shaft (3), a balance weight (5) connected to the elevator car (1) with a traction member (10) from below and with a suspension element (11) from above, a hoisting machinery (6) equipped with a drive wheel (7), a tensioning device (la) and a slack monitoring assembly (28). The tensioning of the traction member (10) is arranged with a group of means comprising at least the tensioning device (la) and at least a part of the weight of the hoisting machinery ( 6).

Description

ARRANGEMENT FOR TENSIONING A TRACTION MEMBER OF AN ELEVATOR AND FOR MONITORING THE TENSION OF THE TRACTION MEMBER

The present invention relates to an arrangement for tension- ing a traction member of an elevator and for monitoring the tension of the traction member as defined in the preamble of claim 1.

The present invention relates mainly elevators where the suspension and moving of the elevator car are separated from each other. In these solutions the elevator car and counterweight or balance weight are suspended by a suspension ele^¬ ment that can be, for instance, a group of parallel ropes or belts or one strong belt only. Whereas the elevator car is moved up and down by one or more traction members that are fastened between the elevator car and counterweight or bal^¬ ance weight. In that case the traction member can be, for instance, a toothed belt. In the following, when only one traction member is mentioned one or more traction members are meant.

One problem with elevators that are mainly used for light loads is keeping the tension of the traction member in a correct level if the traction member has stretched in the course of time. The tensioning arrangements according to prior art are not able to tighten the traction member into the needed tightness if the traction member is stretched too much. In addition the slackening of the traction member or members must be continuously monitored. One possibility ac- cording to prior art technology is to use pretension to keep the traction member or members sufficiently tight also in high buildings. However, a problem in that case is high tensions in the suspension ropes and/or traction members. One object of the present invention is to eliminate draw^¬ backs of prior art technology and to achieve a tensioning arrangement and slack monitoring of a traction member of an elevator, which arrangement contains an active tensioning system that can be used also in high-rise buildings during the run of the elevator car and during the loading and unloading of the elevator car. Another object of the present invention is to achieve a simple, cost effective and compact actively working tensioning arrangement for an elevator, in which arrangement the part of the own mass of the elevator motor can be utilized for tensioning the system. Yet another object of the invention is to achieve a standardized water^¬ proof machinery unit, which is easy to install and can be used in various kinds of elevators without making modifica- tions. The arrangement according to the invention is charac^¬ terized by what is disclosed in the characterization part of claim 1. Other embodiments of the invention are characterized by what is disclosed in the other claims. Preferably the invention is expressed as an arrangement for tensioning a traction member of an elevator and for monitoring the tension of the traction member. The elevator comprises at least an elevator car arranged to run in an eleva^¬ tor shaft along guide rails, a counterweight or balance weight connected to the elevator car with a traction member from below and with a suspension element from above, a hoisting machinery equipped with a drive wheel in the lower part of the elevator shaft, a tensioning device, and a slack monitoring assembly. According to the invention the tension- ing of the traction member is arranged with a group of means comprising at least the tensioning device and at least a part of the weight of the hoisting machinery or the whole weight of the hoisting machinery. In an advantageous embodi^¬ ment there is in addition to the hoisting machinery also an auxiliary power or force device such as a linear actuator or a gas spring or alike to produce additional force for the tensioning of the elevator system. Advantageously the hoisting machinery is fitted inside a wa^¬ terproof casing already at the factory to form an integrated standardized machinery unit that is transported to the in^¬ stallation site and installed at the bottom part of the ele^¬ vator shaft.

The invention makes it possible to achieve an active ten^¬ sioning and slack monitoring system for an elevator in a simple and cost effective way. In addition the standardized machinery unit is easy to install in many kinds of elevators without making modifications at the installation site. The arrangement according to the invention also protects the hoisting machinery from water and other things, such as dust although the machinery is installed at the bottom of the el^¬ evator shaft.

The inventive content of the application can also be defined differently than in the claims presented below. The in^¬ ventive content may also consist of several separate inven^¬ tions, especially if the invention is considered in the light of expressions or implicit sub-tasks or from the point of view of advantages or categories of advantages achieved. In this case, some of the attributes contained in the claims below may be superfluous from the point of view of separate inventive concepts. Likewise the different details presented in connection with each embodiment can also be applied in other embodiments. In addition it can be stated that at least some of the subordinate claims can, in at least some situations, be deemed to be inventive in their own right. One advantage of the arrangement according to the invention is a simple, cost effective and compact structure of the tensioning and tension monitoring arrangement. Another advantage is that the tensioning of the traction member is re- liable and the tension can reliably be kept in a correct level. Yet another advantage is that the own mass of the el^¬ evator motor can be utilized as part of the tensioning arrangement so that the tensioning is always active and does not cause additional tension to the system. Also one ad- vantage is that the number of monitoring means can be re^¬ duced. Yet a further advantage is that the hoisting machin^¬ ery unit can always be similar in many kinds of elevators without any modifications to be made or requiring only minor modifications. Yet a further advantage is that the hoisting machinery unit is placed inside a protective casing that protects the hoisting machinery from water, for example in case of a flood, and from dust, dirt and other debris, and also from other fluids than water. Above-mentioned ad^¬ vantages lead to yet another advantage that the machinery can be normally located at the bottom of the elevator shaft so that it does not take unnecessary space elsewhere in the elevator shaft. Yet another advantage is that the casing be^¬ longing to the arrangement can be used also as a transport means to bring the machinery to the location of the eleva- tor. Yet another advantage is that the casing reduces the noise level of the machinery. Yet a further advantage is that the arrangement contains a fan, which enhances cooling of the machinery, and also the casing can be pressurized us^¬ ing the fan.

In the following, the invention will be described in detail by the aid of example embodiments by referring to the at^¬ tached drawings, wherein Fig. 1 presents in a simplified and diagrammatic front view an elevator, in which the arrangement according to the invention can be used,

Fig. 2 presents in a simplified and diagrammatic oblique top and side view a hoisting machinery used in the arrangement according to the invention,

Fig. 3 presents in a simplified and diagrammatic oblique side view and partially cross-sectioned a tensioning device used in the arrangement according to the in- vention,

Fig. 4 presents in a simplified and diagrammatic side view and partially cross-sectioned a tensioning device used in the arrangement according to the invention,

Fig. 5 presents in a simplified and diagrammatic oblique side and bottom view a tensioning device used in the arrangement according to the invention,

Fig. 6 presents in a simplified and diagrammatic oblique side and top view and enlarged a part of a slack monitoring assembly according to the arrangement in a situation where both the traction members are in the correct tightness,

Fig. 7 presents in a simplified and diagrammatic oblique side and bottom view the slack monitoring assembly according to the arrangement in a situation where one of the traction members is slackened,

Fig. 8 presents in a simplified and diagrammatic oblique side and top view and enlarged a part of the slack monitoring assembly according to the arrangement in the situation of Fig. 7,

Fig. 9 presents in a simplified and diagrammatic oblique side and bottom view the slack monitoring assembly according to the arrangement in a situation where both the traction members are slackened, and Fig. 10 presents in a simplified and diagrammatic oblique side and top view and enlarged a part of the slack monitoring assembly according to the arrangement in the situation of Fig. 9.

The main idea of the invention is to arrange an active ten^¬ sioning and slack monitoring of the traction member of the elevator using a separate tensioning motor and slack monitoring assembly, and at the same time using as additional tensioning the own mass of the elevator hoisting motor that is supported by a lever mechanism that allows the elevator hoisting motor to move up and down suspended at least par^¬ tially by the traction member of the elevator. Figure 1 presents in a simplified and diagrammatic front view an elevator, in which the arrangement according to the invention can be used. The elevator comprises among other things an elevator car 1 that is fitted, for example, inside a sling 2 and arranged to run up and down in the elevator shaft 3 along guide rails 4, and a counterweight or balance weight 5 that is also arranged to run up and down in the el^¬ evator shaft 3 along its guide rails which are not presented in figure 1 for the sake of clarity. Later in this connec^¬ tion only balance weight 5 is mentioned when either counter- weight or balance weight is meant.

The supporting and moving of the elevator car 1 are separated from each other. The elevator car 1 is driven by a hoisting machinery 6 equipped with a drive wheel 7. The hoisting machinery 6 is fitted inside a casing 9 at the bottom part of the elevator shaft 3, below the elevator car 1 and below the first floor level 8. The hoisting machinery 6 is fas^¬ tened for instance on a wall of the elevator shaft, such as a back wall, near the bottom of the elevator shaft. A traction member 10 is connected between the balance weight 5 and the elevator car 1. The traction member 10 can be a single member or a bunch of similar parallel members, for instance, the traction member 10 can be a toothed belt, chain or other type of member that does not slip on the drive wheel 7. In this embodiment the suspension ratio of the traction member 10 is 1:1. In that case the first end of the traction member 10 is secured at the first fastening point 10a in connection with a tensioning device la that is fastened in connection with the elevator car 1. From the tensioning device la the traction member 10 is led downwards to go under and around a the drive wheel 7 of the hoisting machinery 6 at the bottom part of the elevator shaft 3, from where the traction member 10 continues upwards to the bal^¬ ance weight 5 where the second end of the traction member 10 is secured at the second fastening point 10b in connection with the balance weight 5. The elevator car 1 is suspended by suspension element 11 that is connected between the balance weight 5 and the ele^¬ vator car 1. The suspension element 11 can be a single member or a bunch of similar parallel members, for instance suspension ropes. The first ends of the suspension element 11 are secured to the upper part of the balance weight 5 and from the balance weight 5 the suspension element 11 is led upwards to go over and around a diverting pulley 12 that is fitted with bearings on its shaft, for instance at a support beam 13 which is fastened, for example, to the upper part of the guide rails 4 above the elevator car 1. From the divert^¬ ing pulley 12 the suspension element 11 descends to the ele^¬ vator car 1 where the second end of the suspension element 11 is secured in connection with the upper part of the ele^¬ vator car 1. At the bottom of the elevator shaft 3 there are also buffers 14 to stop the elevator car 1 descending too down .

Figure 2 presents in a simplified and diagrammatic oblique top and side view a hoisting machinery 6 used in the arrangement according to the invention. As shown in figure 2 the hoisting machinery 6 is preferably fitted inside the casing 9. The hoisting machinery 6 and the casing 9 together form an integrated machinery unit, or only a machinery unit 6a. The machinery unit 6a is assembled at a factory and af^¬ ter that transported to its destination and installed to the bottom part of the elevator shaft as one unit. The hoisting machinery 6 and its casing 9 are installed inside a frame structure 9a and secured, for example, to the wall or walls of the elevator shaft 3 with help of securing means, which in this case comprise for example brackets, bolts and nuts. The machinery unit 6a is secured to the wall or walls of the elevator shaft 3 through the frame structure 9a so that the fastening bolts used do not penetrate the casing 9 which would allow a situation for water to enter inside the casing 9.

The casing 9 comprises a detachable cover 16. The cover 16 is arranged to close the casing 9 so that the casing 9 is waterproof. The casing 9 and the cover 16 can be made of the same material or the materials can also be different from each other. For example, the casing 9 can be made of plastic and the cover 16 of some metal, such as steel or aluminum. In such a case, the cover 16 acts also as a cooling element. In this embodiment the cover 16 is arranged to be attached to the casing 9 with help of clips 18.

At the upper part of the casing 9 there is an opening 17 for the traction member 10 to enter the casing 9 and to exit the casing 9 when the traction member makes 10 its turn around the drive wheel 7 inside the casing 9. The arrangement also comprises a cover means in connection with the opening 17 to prevent water from entering the casing 9, for example in case of a flood when water may enter the elevator shaft. The cover means could be for instance a bellows-like cover or a corresponding means, which is arranged to rise along with water if the water surface level rises above the opening 17. Also a ventilation pipe 19 belongs to the casing 9. The ven^¬ tilation pipe 19 can, for instance, be shaped substantially like a downwardly opening semicircle or alike where its first end starts upwards from the upper part of the casing 9 and the second end points freely downwards. Inside the cas- ing 9 there is also an elevator motor 15, drive 15a and a fan 15b that is between the elevator motor 15 and the drive 15a and is arranged to take care of ventilation of the hoisting machinery 6 through the ventilation pipe 19. According to one advantageous embodiment of the invention preferably at least the elevator motor 15 and the drive wheel 7 in the hoisting machinery 6 are suspended floating by the lever mechanism 20 that allows the elevator motor 15 and the drive wheel 7 to move up and down in certain limits caused by the own mass of the elevator motor 15 and the drive wheel 7. This helps in its part the tensioning of the traction member 10 and the whole elevator system. The lever mechanism 20 comprises at least a substantially vertical support element, an upper lever arm 20a, a lower lever arm 20b, an upper frame part 20c and a lower frame part 20d. The upper frame part 20c and lower frame part 20d are advanta^¬ geously joined to each other as one integrated part. The first ends of the lever arms 20a, 20b are connected to the vertical support element with joint pins so that the lever arms 20a, 20b can pivot in relation to the support el^¬ ement. Correspondingly the second end of the upper lever arm 20a is pivoted to the upper frame part 20c with a joint pin and the second end of the lower lever arm 20b is pivoted to the lower frame part 20d with a joint pin. The frame parts 20c, 20d and the lever arms 20a, 20b and their mutual geome^¬ try are arranged to suspend the elevator motor 15 and the drive wheel 7 in a floating way so that the elevator motor 15 and drive wheel 7 can move substantially freely up and down in certain limits, and at the same time keep the trac^¬ tion member 10 and the whole elevator system tensioned suit^¬ ably tight.

As seen in figure 2 the lever mechanism 20 according to the embodiment of the example comprises for instance one upper lever arm 20a and two parallel lower lever arms 20b with a distance from each other. The parallel lower lever arms 20b are connected to each other with the joint pins to form a stiff unit.

The lever mechanism 20 is arranged to support the elevator motor 15 and the drive wheel 7 and other parts of the hoist- ing machinery 6 so that the joint pin at the outer or second end of the lower lever arms 20b is fastened at its second end to the casing of the elevator motor 15 and the combina^¬ tion of the frame parts 20c, 20d is fitted, for example with bearings on the shaft of the elevator motor 15.

The hoisting machinery 6 also comprises an auxiliary power device 7a such as a gas spring to produce additional force for the tensioning of the elevator system. This kind of auxiliary power device 7a is needed particularly in big eleva- tors, for instance in high-rise buildings, if the own mass of the elevator motor 15 or the entire hoisting machinery 6 is not sufficient. Instead of gas springs other auxiliary power devices can also be used, such as linear actuators, gear motors, hydraulic actuators or air-driven actuators. The auxiliary power device 7a is connected to the tension control system and is arranged, for instance, between the frame of the hoisting machinery 6 and the elevator motor 15 to press the elevator motor 15 downwards when needed. A pow- er source of the auxiliary power device 7a is, for example, an electrically controlled solenoid.

Figures 3 and 4 present in a simplified and diagrammatic view and partially cross-sectioned a tensioning device la used in the arrangement according to the invention. Figure 3 is seen from the first side of the tensioning device la and cross-sectioned about the middle line of the frame 21 of the tensioning device la. Whereas figure 4 is seen from the sec^¬ ond side of the tensioning device la and cross-sectioned so that the tensioning motor 22 has been cut away in front of the arrester 24.

The tensioning device la is secured to a mounting element lb, which is fitted for example in connection with the bot- torn part of the elevator car 1. The tensioning device la is secured to the frame 21 of the mounting element lb with help of securing means lc, which in this case comprise for exam^¬ ple bolts and nuts. The frame 21 of the tensioning device la is a downwardly opening, substantially U-shaped metal ele- ment or alike. The tensioning device la comprises the frame 21, a tensioning motor 22, a limiting member 23, an arrester 24 such as a ratchet wheel or a diode bearing, a lever member 25, which is in connection with the arrester 24, a ten- sioning spring 26, a monitoring member 27 and a slack monitoring assembly 28.

In connection with the tensioning device la there are also the first fastening point 10a for the traction member 10, a first tensioning pulley 10c and a second tensioning pulley lOd. The first end of the traction member 10 is secured at the first fastening point 10a with help of securing means lOe and from the first fastening point 10a the traction mem- ber 10 is led to go around under the first tensioning pulley 10c and then around and over the second tensioning pulley lOd, after which the traction member 10 is led downwards to the drive wheel 7 of the hoisting machinery 6 at the bottom part of the elevator shaft 3.

The tensioning pulleys 10c and lOd are fitted with bearings on their shafts inside the frame 21 in such a way that the first tensioning pulley 10c is fitted lower than the second tensioning pulley lOd and nearer the fastening point 10a of the traction member 10. The ends of the shaft of the first tensioning pulley 10c are fitted in obliquely sideways elon^¬ gated holes, which act as guide grooves 29 at the vertical side flanges of the frame 21 so that the shaft can move along these guide grooves 29. This means that also the first tensioning pulley 10c is arranged to move obliquely sideways guided and limited by the guide grooves 29. Thus, the dis^¬ tance of the first tensioning pulley 10c from the second tensioning pulley lOd is arranged to be varied. When the first tensioning pulley 10c moves further from the second tensioning pulley lOd the traction member 10 tightens and vice versa. The tensioning pulleys 10c, lOd act as tension^¬ ing means that take off the excess slackness of the traction member 10. In normal circumstances the tensioning spring 26 is arranged to keep the tension of the traction member 10 in a correct level pushing the lever member 25 upwards. The monitoring member 27 is arranged to monitor the tension of the traction member 10 and start the tensioning motor 22 if the traction member 10 slackens too much. In such a case, the tensioning motor 22 is arranged to pull and tighten the traction member 10 by turning the lever member 25 so that it pushes the ten^¬ sioning spring 26 downwards. When the correct tension level of the traction member 10 is reached the monitoring member 27 is arranged to turn off the tensioning motor 22. The ar- rester 24 is arranged to prevent the lever member 25 turning upwards and the traction member 10 to return to the slackened state. The limiting member 23 is arranged to prevent the system to rotate too much in case if, for example the arrester 24 breaks.

The tensioning device la described above is arranged to mon^¬ itor the tension of the traction member 10 actively and correct the tension right away if the traction member 10 slackens. However, instead of monitoring the tension actively the monitoring and possible correction of the tension can also be done at preset times.

Figures 5-10 present in a more detailed way the slack moni^¬ toring assembly 28 according to the arrangement. Figures 5, 7 and 9 present in a simplified and diagrammatic oblique side and bottom view the tensioning device used in the arrangement according to the invention and figures 6, 8 and 10 presents in a simplified and diagrammatic oblique side and top view and enlarged a part of the slack monitoring assem- bly 28 according to the arrangement.

The tensioning motor 22, the arrester 24 and the tensioning spring 26 are fitted at the outer side of the first side flange of the frame 21. In this embodiment there are two parallel traction members 10, which are for example toothed belts. There are also two parallel first tensioning pulleys 10c and two parallel second tensioning pulleys lOd fitted inside the frame 21. The slack monitoring assembly 28 is fitted at the other side of the tensioning pulleys 10c, lOd compared to the fastening points 10a of the traction members 10. The slack monitoring assembly 28 is arranged to monitor if one or both of the traction members 10 are suddenly slackened significantly or even cut. The slack monitoring assembly 28 does not react to slight slackening. In the sit^¬ uation of the figures 5 and 6 both the traction members 10 are in the correct tightness.

The slack monitoring assembly 28 comprises a body part 29, which is secured to the frame 21 of the tensioning device la, a monitoring member 30, which contains a stud 31 at its bottom part, a flange 32, a first monitoring spring 33, a second monitoring spring 34 and a counterpart 35 of the mon^¬ itoring member 30. The counterpart 35 is an upwards open cup-shaped member with a substantially circular edge 36 and it is fitted under the monitoring member 30 in such a way that the stud 31 is fitted inside the cup. In addition, the monitoring member 30 contains a spring or alike, which is arranged to push the stud 31 down towards the counterpart 35. The slack monitoring assembly 28 also contains means, which are arranged to send information to the control system of the elevator if one or both or the traction members 10 are slackened or cut.

The slack monitoring assembly 28 is in connection with both traction members 10 via connection members 32a connected to the flange 32. This can be seen more clearly in figure 4. The flange 32 is secured to the bottom part of the body part 29 and in the flange 32 there are two openings 37 with two spring holders 38, at which the springs 33 and 34 are fit^¬ ted. The springs 33 and 34 are arranged to push the connec- tion members 32a towards the traction members 10. The ten^¬ sion of the springs 33 and 34 is fitted in such a way that when both traction members 10 are in the correct tightness the tension of the traction members 10 keeps the slack moni^¬ toring assembly 28 in normal state, where the stud 31 is down around in the middle of the cup of the counterpart 35.

Figures 7 and 8 present a situation where one of the trac^¬ tion members 10 is slackened. In this situation the second traction member 10 is slackened and its tension is too low to keep the second spring 34 at its normal state. Hence the second spring 34 has pushed the second edge of the flange 32 and the second connection member 32a towards the second traction member 10 and the flange 32 with the counterpart 35 has rotated sideways. The stud 31 can move only up and down and now the sideways displacement of the counterpart 35 has forced the stud 31 to move upwards from the middle of the counterpart 35 to the edge 36 of the counterpart 35. When the stud 31 moves a predefined amount upwards the slack mon^¬ itoring assembly 28 is activated and it is arranged to send information about the situation to the control system of the elevator for further actions.

Figures 9 and 10 present a situation where both the traction members 10 are slackened. In this situation both the springs 33 and 34 have pushed the flange 32 towards the traction members 10 and the counterpart 35 also has moved towards the traction members 10 in which case the counterpart 35 has forced the stud 31 to move upwards from the middle of the counterpart 35 to the edge 36 of the counterpart 35. Also in this case the slack monitoring assembly 28 is arranged to send information about this situation to the control system of the elevator.

It is obvious to the person skilled in the art that the in^¬ vention is not restricted to the examples described above but that it may be varied within the scope of the claims presented below. Thus, for instance, the elevator can also be different from the elevator described above. For example the suspension ratio of the elevator can be different. Also the hoisting machinery and other parts of the elevator can be different from what is described above.

It is also obvious to the person skilled in the art that the tensioning device can also be fitted elsewhere as in connec^¬ tion with the elevator car. It is further obvious to the person skilled in the art that there can also be different amount of traction members in the elevator instead of two. For example, there can be only one traction member or three or more traction members. And it is yet further obvious to the person skilled in the art that the structure of the tensioning device and the slack monitoring assembly can also differ from the embodiment described above. However, the operational principle can be the same.

Claims

1. Arrangement for tensioning a traction member of an elevator and for monitoring the tension of the traction member, which elevator comprises at least an elevator car (1) arranged to run in an elevator shaft (3) along guide rails (4), a counterweight or balance weight (5) connected to the elevator car (1) with a traction member (10) from below and with a suspension element (11) from above, a hoisting ma- chinery (6) equipped with a drive wheel (7) arranged to drive the traction member (10) in the lower part of the ele^¬ vator shaft (3), a tensioning device (la) and a slack monitoring assembly (28), characterized in that the tensioning of the traction member (10) is arranged with a group of means comprising the tensioning device (la) and at least a part of the weight of the hoisting machinery (6) .

2. Arrangement according to claim 1, characterized in that the tensioning of the traction member (10) is arranged with a group of means comprising the tensioning device (la) and the weight of the hoisting machinery (6) .

3. Arrangement according to claim 1 or 2, characterized in that the arrangement comprises an auxiliary power device (7a) arranged to produce additional force for the tensioning of the traction member (10) and/or to the elevator system.

4. Arrangement according to claim 3, characterized in that the auxiliary power device (7a) is arranged between the frame of the hoisting machinery (6) and the elevator motor (15) .

5. Arrangement according to claim 3 or 4, characterized in that the auxiliary power device (7a) is connected to the tension control system of the elevator.

6. Arrangement according to any of the claims above, characterized in that the tensioning device (la) comprises a ten^¬ sioning spring (26) and an arrester (24) with a lever member (25) , which combination in its own part is arranged to keep the traction member (10) in the correct tension.

7. Arrangement according to any of the claims above, characterized in that the tensioning device (la) comprises a ten^¬ sioning motor (22) with tensioning means, which combination is arranged to correct the tension of the traction member (10) when needed if the tension differs from the correct level, and a monitoring member (27), which is arranged to monitor the tension of the traction member (10) .

8. Arrangement according to claim 7, characterized in that the tensioning means comprises at least a first tensioning pulley (10c) and a second tensioning pulley (lOd), and that the position of the first tensioning pulley (10c) is ar^¬ ranged to be moved in relation to the second tensioning pul^¬ ley (lOd) .

9. Arrangement according to any of the claims above, characterized in that the drive wheel (7) and elevator motor (15) are supported by a lever mechanism (20) which is arranged to allow the drive wheel (7) and elevator motor (15) to move up and down, and thus in its own part tighten the traction member (10) .

10. Arrangement according to claim 9, characterized in that the traction member (10) is arranged to suspend the drive wheel (7) and elevator motor (15), and the own mass of the drive wheel (7) and elevator motor (15) is arranged to form an active tensioning system in order to tension the elevator system in its own part.

11. Arrangement according to any of the claims above, characterized in that the slack monitoring assembly (28) is ar- ranged to monitor if the tension of the traction member (10) is suddenly decreased significantly or if the traction mem^¬ ber (10) is cut.

12. Arrangement according to any of the claims above, char- acterized in that the slack monitoring assembly (28) com^¬ prises a monitoring member (30), which contains an up and down moving stud (31) acting as a switch, a counterpart (35) operating together with the stud (31), and at least one mon^¬ itoring spring (33, 34) interacting to change the position of the counterpart (35) .

13. Arrangement according to any of the claims above, characterized in that the hoisting machinery 6 is fitted inside a waterproof protective casing 9 and the hoisting machinery 6 and the casing 9 together are arranged to form an inte^¬ grated machinery unit 6a.