Technical field

[0001 ] The present disclosure relates generally to a turntable for lifting and rotating a paper bale, wherein the turntable comprises a turning unit, an electrical motor and a gear arrangement configured to convert torque from the electrical motor to a vertical movement and a rotating movement of the turning unit. The present disclosure further relates to a paper bale wrapper folding machine comprising said turntable.

Background art

[0002] In paper manufacturing, once a paper bale is manufactured, the paper bale is usually wrapped in some kind of protecting wrapping such as pulp sheets or roll paper. A common alternative is to utilize a wrapper folding machine that folds paper packaging around the bales. Such a solution is disclosed in, for instance, US 3327452 A.

[0003] Traditionally, the rotating and lifting (vertical) movements of a turntable utilised in a paper bale wrapper folding machine have been driven by hydraulics. In a conventional hydraulically driven turntable at least three pneumatic cylinders are needed to perform the lifting and rotation of the turntable, one cylinder for the lifting movement and two cylinders for the rotating movement.

[0004] However, in recent years, there has been a growing trend towards electrification of industrial machineries as electrically driven machines usually require less maintenance and are more reliable compared to a hydraulically driven machine of the same kind. Furthermore, electrically driven machines vis-a-vis hydraulically driven machines also have the advantage that there are improved possibilities regarding speed, torque and movement control.

[0005] As hydraulically driven machines are usually loud, replacing them with electrical alternatives also improves the working environment for operators in close vicinity. [0006] In a paper bale wrapper folding machine, a paper bale enters a folding section by means of a conveyor and is placed on a turntable. The paper bale is then lifted by the turntable to a height that allows the paper bale to rotate freely above the conveyor. Once in the elevated position, wrapping paper is folded around the paper bale with the help of folding arms by rotating the paper bale using the turntable. When the wrapping paper has been folded around the paper bale, the bale is lowered and transported to a subsequent section by a subsequent conveyor.

[0007] As previously described, traditionally the turntable has been driven by hydraulics which requires high maintenance and has limited process control possibilities. As such, there is therefore a need for an improved turntable arrangement that eliminates the use of hydraulic operation and solving the above stated problems.

Summary of invention

[0008] An object of embodiments of the present disclosure is to provide a turntable for lifting and rotating a paper bale, which replaces hydraulic operation of the turntable with electrical operation.

[0009] A further object of embodiments of the present disclosure is to provide a turntable that utilizes an electrical motor to power a lifting movement and a rotating movement of the turntable.

[0010] A further object of embodiments of the present disclosure is to provide an electrically driven turntable that has similar cycle times and similar dimensions as a hydraulically driven turntable.

[0011 ] Another object of embodiments of the present disclosure is to provide a paper bale wrapper folding machine comprising a turntable according to any of the previous objects.

[0012] In a first aspect, the present disclosure is directed to a turntable for lifting and rotating a paper bale. The turntable comprises a turning unit comprising an upper part, a connecting section and a lower part. The upper part of the turning unit comprises a planar upper surface configured to receive a paper bale. The connecting section of the turning unit extends downwards from the upper part towards the lower part. Further, the turntable comprises an electrical motor comprising a driving shaft. Further, the turntable comprises a gear arrangement in driving engagement with the driving shaft of the electrical motor, the connecting section and/or the lower part of the turning unit. The gear arrangement is configured to convert torque from the electrical motor to a vertical movement and a rotating movement of the turning unit.

[0013] The upper surface may be planar and configured to receive a paper bale from a conveyor of a paper bale wrapper folding machine. The upper surface may further be configured to engage with the conveyor to remove the paper bale from the turning unit once lifting and rotation of the turning unit has been performed and deliver the wrapped paper bale to a subsequent section.

[0014] An exemplary effect of the turntable according to what is disclosed herein, is that the no hydraulic components are needed to lift and rotate the turning unit of the turntable. By this, a turntable requiring less maintenance is achieved. Furthermore, as an electrical motor is only active during a wrapping cycle of a paper bale, i.e. from the start of the first lifting of the turning unit to the final lowering of the turning unit, compared to a hydraulic component that is also active in between lifting cycles, an overall energy reduction is also achieved.

[0015] An exemplary effect of the turntable according to what is disclosed herein, is that since an electrical motor is smaller than a hydraulic operation system, it is possible to replace conventional turntables with the turntable according to embodiments of the present disclosure as the dimensions can be tailored similarly.

[0016] The vertical movement of the turning unit may be less than 100 mm, preferably approximately 70 mm. In one embodiment, the rotating movement of the turning unit is 90°. In one embodiment, the rotating movement of the turning unit is [0017] The turntable may be configured to be operable with a paper bale wrapper folding machine.

[0018] In one exemplary turntable, the turntable further comprises a housing comprising an upper opening, and wherein the connecting section extends through the upper opening of the housing.

[0019] In one exemplary turntable, the turntable comprises one single electrical motor, and wherein the electrical motor provides the force required to perform the vertical movement and the rotating movement of the turning unit.

[0020] By such an exemplary turntable, even less maintenance compared to a conventional hydraulically driven turntable is required as only one electrical motor is required to both lift and rotate the turning unit. As only one electrical motor is required, also only one gear arrangement is needed, which further simplifies the maintenance requirements of the turntable.

[0021 ] In one exemplary turntable, the gear arrangement is selected from a bevel gear system comprising a camshaft, a chain drive system with separate gears for lifting and rotation, a differential gear system, or a planetary gear system.

[0022] In one exemplary turntable the lower part of the turning unit comprises a lower surface arranged at the bottom of the connecting section, wherein the lower surface is opposite to the upper surface. The lower surface may be parallel to the upper surface.

[0023] In one exemplary turntable the gear arrangement is a bevel gear system comprising at least one cam arranged on the driving shaft of the electrical motor and extending in a direction perpendicular to a longitudinal axis of the driving shaft. Further, the at least one cam comprises a bevel gear arranged on a free end thereof. An axis of the bevel gear is parallel to the driving shaft of the electrical motor. The at least one cam is arranged to rotate with the driving shaft of the electrical motor to contact the lower surface and cause a vertical movement of the turning unit. Further, the bevel gear is arranged to engage with a corresponding second circular bevel gear arranged on the lower surface to cause a rotating movement of the turning unit. [0024] By such an exemplary turntable, the electrical motor and the gear arrangement engages with one another to both lift and rotate the turning unit.

[0025] In one exemplary turntable, the bevel gear system comprises two cams, each cam comprising a bevel gear as disclosed herein. By such an exemplary turntable, the cycle times of the turntable can be decreased as the second cam engages with the lower surface of the turning unit when the first cam has completed its lifting and rotating engagement with the lower surface. As such, it is not necessary to wait that a sole cam rotates 180° around the driving shaft of the electrical motor before engaging with the lower surface of the turning unit again.

[0026] The electrical motor may be located inside or outside the housing of the turntable.

[0027] In one exemplary turntable, the gear arrangement is a chain drive system with separate gears for vertical and rotational movement of the turning unit. The gear arrangement comprises a first sprocket gear rotatable by the driving shaft of the electrical motor. The gear arrangement further comprises a drive chain passing over the first sprocket gear. The gear arrangement further comprises a second sprocket gear arranged at a first end of a first shaft, the first shaft further comprising a first bevel gear arranged at a second end of the first shaft. The first bevel gear is configured to engage with a corresponding second bevel gear arranged on the lower part of the turning unit, wherein the engagement of the first bevel gear with the second bevel gear causes a rotating movement of the turning unit. The gear arrangement further comprises a third sprocket gear arranged at a second end of a second shaft, the second shaft further comprising a cylindrical gear arranged at a second end of the second shaft. The cylindrical gear is configured to engage with a corresponding gear rack arranged on the connecting section of the turning unit, the engagement of the cylindrical gear with the gear rack causes a vertical movement of the turning unit. Further, the gear arrangement further comprises means to shift the position of the drive chain to either engage with the second sprocket gear or the third sprocket gear. [0028] The means to shift the position of the drive chain may be selected from any suitable mean able to shift the position from a sprocket gear to another sprocket gear, for instance by a bicycle gear type of shift arrangement. However, other types of arrangements able to shift position from a sprocket gear to another sprocket gear known to the skilled person can be utilised as well.

[0029] In one exemplary turntable, the gear arrangement is a differential gear system. The gear arrangement comprises a differential being in gear engagement with the driving shaft of the electrical motor. The differential comprises a planet carrier rotatable by the driving shaft of the electrical motor, a planet gear arranged on the planet carrier, a first sun gear and a second sun gear in driving engagement with the planet gear. Further, the first sun gear is arranged to drive a first shaft and the second sun gear is arranged to drive a second shaft. The first shaft and the second shaft are each connected to a respective brake system. Further, the first shaft comprises a first cylindrical gear arranged to engage with a corresponding fixed gear rack arranged on a fixed wall. The engagement of the first cylindrical gear with the fixed gear rack causes a vertical movement of the turning unit. Further, the second shaft comprises a first bevel gear arranged to engage with a corresponding second bevel gear arranged on a third shaft. Further, the third shaft further comprises a second cylindrical gear arranged to engage with a corresponding third cylindrical gear arranged on the connection section of the turntable. The engagement of the second cylindrical gear with the third cylindrical gear causes a rotating movement of the turning unit.

[0030] The fixed wall on which the fixed gear rack is arranged on may be a wall of the housing of the turntable.

[0031 ] By such an exemplary turntable, only one electrical motor is needed to both lift and rotate the turning unit. The brake system allows for controlling the rotational speed of the first shaft and second shaft, and hence allows controlling the respective movement that each shaft is responsible for. Furthermore, the use of a differential gear arrangement allows for a system comprising fewer moving parts shifting that alternate positions, thus resulting in a reduced failure risk and a more durable system.

[0032] In one exemplary turntable, the gear arrangement is a planetary gear system. The gear arrangement comprises a sun gear arranged at the end of the driving shaft of the electrical motor. Further, the gear arrangement comprises a planet carrier arranged in fixed engagement with the connecting section of the turning unit, wherein rotation of the planet carrier causes a rotational movement of the turning unit. Further, the gear arrangement further comprises planet gears arranged on the planet carrier and in driving engagement with the sun gear. Further, the gear arrangement further comprises a ring gear enclosing the planet gears, wherein the ring gear comprises gears on both the inside of the ring and outside of the ring. The inside of the ring gear is in driving engagement with the planet gears, and wherein the outside of the ring gear is in driving engagement with two cylindrical gears. Further, the cylindrical gears comprising a shaft having a ballscrew arrangement, wherein the ballscrew arrangement is in driving engagement with a threaded nut that is in fixed engagement with the connecting section of the turning unit. The rotation of the ballscrew arrangement causes vertical movement of the turning unit.

[0033] By such an exemplary turntable, a simpler, more space effective turntable is achieved as components can be closely placed inside the structure of the turntable. As such, it is possible to fit such an exemplary turntable within the same space as conventional turntables driven by hydraulics. Furthermore, such an exemplary turntable allows for easy and safe maintenance work, thus increasing the overall safety of a working environment.

[0034] As a planetary gear system enables to lock either the planet carrier or the ring gear, it is possible to control if the turning unit is to be lifted vertically or be rotated. If the planet carrier is kept locked, i.e. fixed, the ring gear drives the vertical movement and if the ring wheel is kept fixed, the planet carrier drives the rotational movement. [0035] In one exemplary turntable, the locking of the planet carriers and the ring gear is performed using a solenoid.

[0036] In one exemplary turntable, the gear arrangement is a planetary gear system. The gear arrangement comprises a sun gear arranged at the end of the driving shaft of the electrical motor. Further, the gear arrangement comprises a planet carrier arranged in fixed engagement with the connecting section of the turning unit, wherein rotation of the planet carrier causes a rotating movement the turning unit. Further, the gear arrangement comprises planet gears arranged on the planet carrier and in driving engagement with the sun gear. Further, the gear arrangement comprises a ring gear enclosing the planet gears wherein the inside of the ring gear is in driving engagement with the planet gears. The ring gear is arranged in fixed engagement with an outer cylinder surrounding the connecting section, wherein the outer cylinder comprises an outside screw thread in engagement with a nut fixed to a fixed part. The rotation of the outer cylinder causes a vertical movement of the turning unit.

[0037] The fixed part on which the nut is fixed to may be the housing of the turntable.

[0038] By such an exemplary turntable, an even more compact and space effective turntable is achieved as components can be closely placed inside the structure of the turntable. As such, it is possible to fit such an exemplary turntable within the same space as conventional ones driven by hydraulics, or even decrease the overall volume of a turntable. Furthermore, such an exemplary turntable is even more safe when performing maintenance work as fewer rotating parts are present in the turntable.

[0039] In a second aspect, the present disclosure is directed to a paper bale folding machine. The paper bale folding machine comprises means for transporting a paper bale to and from a turntable. Further, the folding machine comprises a turntable according to the first aspect. Further, the folding machine comprises folding means configured to, when the paper bale is rotated by the turntable, fold and close a wrapping paper around the paper bale. Brief description of drawings

[0040] The invention is now described, by way of example, with reference to the accompanying drawings, in which the same reference notations denote similar items in the various figures, and in which:

[0041 ] Fig. 1 schematically shows a turntable in accordance with one embodiment of the present disclosure comprising a gear arrangement in the form of a bevel gear system.

[0042] Fig. 2 schematically shows a turntable in accordance with one embodiment of the present disclosure comprising a gear arrangement in the form of a chain drive system.

[0043] Fig. 3 schematically shows a turntable in accordance with one embodiment of the present disclosure comprising a gear arrangement in the form of a differential gear system.

[0044] Fig. 4 schematically shows a turntable in accordance with one embodiment of the present disclosure comprising a gear arrangement in the form of a planetary gear system.

[0045] Fig. 5 schematically shows a turntable in accordance with one embodiment of the present disclosure comprising a gear arrangement in the form of a planetary gear system.

Description of embodiments

[0046] The detailed description with reference to the disclosed embodiments are to be viewed as examples of combining specific features described above. It is to be understood that additional examples may be achieved by combining other and/or fewer/more features than in the disclosed embodiments. Hence, the figures disclose exemplary embodiments and not exclusive combinations. In this context is should also be noted that, for the sake of simplicity, all figures are schematically disclosed, as long as nothing else is said. [0047] Figure 1 shows a schematic representation of a turntable 1 in accordance with one embodiment of the present disclosure. The turntable 1 illustrated in figure

I comprises a housing 2 with an opening 211 at its top part. A connecting section 5 of a turning unit 3 extends through the opening 211. The turning unit 3 comprises an upper part 4, the connecting section 5 and a lower part 6. As can be seen in figure 1 , the connecting section 5 extends downwards from the upper part 4 towards the lower part 6 of the turning unit 3. Furthermore, the upper part 4 comprises a planar upper surface 7 configured to receive a paper bale to be lifted and rotated.

[0048] Further present in the turntable 1 according to figure 1 is single electrical motor M comprising a driving shaft 8. The electrical motor M may be any electrical motor suitable to lift and rotate the turning unit 3.

[0049] The gear arrangement illustrated in figure 1 is a bevel gear arrangement. As previously described, the gear arrangement is configured to convert torque from the electrical motor M to a vertical movement and a rotating movement of the turning unit 3.

[0050] Arranged on the driving shaft 8 of the electrical motor M in the embodiment illustrated in figure 1 , are two cams 10. The cams 10 each comprises a bevel gear

I I arranged on a free end of the bevel cams 10. As the two cams 10 are arranged on the driving shaft 8, when the driving shaft 8 rotates as a result from a torque output from the electrical motor, also the two cams 10 will rotate along with the driving shaft 8. This results in the bevel gear 11 to contact a lower surface 9 of the lower part 6, When the rotation continues, this results in a vertical, i.e. lifting, movement of the turning unit 3. At a certain point of rotation of the driving shaft 8, one of the bevel gears 11 engages with a corresponding second circular bevel gear 12 arranged on the lower surface 9. As the bevel gear 11 and the corresponding second circular bevel gear 12 engages, this causes a rotating movement of the turning unit 3.

[0051 ] By corresponding, is meant that the pattern of the bevel gear 11 matches the pattern of the second circular bevel gear 12, thus resulting in a driving engagement. [0052] The two cams 10 are arranged in such a manner that when one cam 10 has completed its lifting and rotating movement of the turning unit 3, the other cam of the two cams 10 engages with the lower surface 9, and the movements are repeated.

[0053] In the embodiment illustrated in figure 1 , the electrical motor M is located outside the housing 2. However, the motor can also be located inside the housing 2.

[0054] Turning now to figure 2, illustrating another turntable 1 in accordance with an embodiment of the present disclosure. The turntable 1 illustrated in figure 2 comprises similarly to the embodiment illustrated in figure 1 , a housing 2, a single electrical motor M with a driving shaft 8, a turning unit 3 comprising an upper part 4 with a planer upper surface 7, a connecting section 5 and a lower part 6.

[0055] The turntable illustrated in figure 2 comprises a gear arrangement being a chain drive system with separate gears. As can be seen, the gear arrangement comprises a first sprocket gear 12 arranged to be rotatable by the driving shaft 8 of the electrical motor M. In figure 2, the first sprocket gear is arranged at one of the lateral ends of the driving shaft 8. Passing over the first sprocket gear 12 is a drive chain 13. The drive chain 13 can by means 22 to shift the position of the chain 13 either engage with a second sprocket gear 14 or a third sprocket gear 18.

[0056] The second sprocket gear 14 is arranged at a first end of a first shaft 15. On a second end of the first shaft 15, opposite to the first end, is a first bevel gear 16. The first bevel gear 16 is arranged to engage with a corresponding second bevel gear 17 arranged on the lower part 6 of the turning unit 3. If the chain drive 13 passes over the first sprocket gear 12 and the second sprocket gear 14, the first bevel gear 16 rotates, i.e. engages, with the second bevel gear 17, thus resulting in a rotating movement of the turning unit 3.

[0057] The third sprocket gear 18 is arranged at a first end of a second shaft 19. On a second end of the second shaft 19, opposite to the first end, is a cylindrical gear 20. The cylindrical gear 20 is arranged to engage with a corresponding gear rack 21 arranged on the connecting section 5 of the turning unit 3. If the chain drive 13 passes over the first sprocket gear 12 and the third sprocket gear 18, the cylindrical gear 20 rotates, i.e. engages, with the gear rack 21 , thus resulting in a vertical movement of the turning unit 3.

[0058] The gear rack 21 is in figure 2 illustrated as a vertical stripe. However, it is to be understood that the gear rack 21 can also extend through the whole circumference of the connecting section 5.

[0059] In order to shift the position of the drive chain 13 to either pass over the second sprocket gear 14 or the third sprocket gear 18, means 22 to shift the position of the drive chain are utilized. As previously described, the means to shift the position of the drive chain may be selected from any suitable mean able to shift the position from a sprocket gear to another sprocket gear, for instance by a bicycle gear type of shift arrangement. However, other types of arrangements able to shift position from a sprocket gear to another sprocket gear known to the skilled person can be utilised as well.

[0060] Turning now to figure 3, illustrating another turntable 1 in accordance with an embodiment of the present disclosure. The turntable 1 illustrated in figure 3 comprises similarly to the embodiment illustrated in figure 1 , a housing 2, a single electrical motor M with a driving shaft 8, a turning unit 3 comprising an upper part 4 with a planar upper surface 7 and a connecting section 5 and a lower part (not illustrated in figure 3).

[0061 ] The turntable illustrated in figure 3 comprises a gear arrangement being a differential gear system. As can be seen, the gear arrangement comprises a differential D that is in gear engagement with the driving shaft 8 of the electrical motor M. The differential D comprises a planet carrier 23 that is rotatable by the driving shaft 8, a planet gear 24 arranged on the planet carrier 23, a first sun gear 25 and a second sun gear 26 in driving engagement with the planet gear 24. The first sun gear 25 is arranged to drive a first shaft 27 and the second sun gear 26 is arranged to drive a second shaft 28. [0062] The rotation of the planet carrier 23 by the driving shaft 8 can be performed by any time of suitable arrangement know to the skilled person, such as a gear arrangement for instance.

[0063] In order to control the rotation of the first shaft 27 and the second 28, each of the first shaft 27 and the second shaft 28 are connected to a respective brake system B. As such, it is possible to rotate the two shafts at different speeds.

[0064] The first shaft 27 and its resulting engagements will now be described in more detail. The first shaft 27 comprises a first cylindrical gear 29 arranged to engage with a corresponding fixed gear rack 30 arranged on a housing 2 wall. When the first shaft 27 rotates, thus causing the first cylindrical gear 29 rotate, the cylinder gear 29 engages with the fixed gear rack 30 causing a vertical movement of the turning unit 3.

[0065] The second shaft 28 and its resulting engagements will now be described in more detail. The second shaft 28 comprises a first bevel gear 31 . The first bevel gear 31 is further arranged to engage with a corresponding second bevel gear 32 arranged on a separate third shaft 33. The third shaft 33 further comprises a second cylindrical gear 34 arranged to engage with a corresponding third cylindrical gear 35 arranged on the connection section 5 of the turning unit 3. When the third shaft 33 rotates, thus causing the second cylindrical gear 34 to rotate, the second cylindrical gear 34 engages with the third cylindrical gear 35 causing a rotating movement of the turning unit 3.

[0066] In the embodiment illustrated in figure 3, the gear system comprising the differential and the turning unit 3 are arranged in such a manner that when the vertical movement of the turning unit 3 occurs as previously described, also the differential and the electrical motor M will be vertically displaced.

[0067] Turning now to figure 4, illustrating another turntable 1 in accordance with an embodiment of the present disclosure. The turntable 1 illustrated in figure 4 comprises similarly to the embodiment illustrated in figure 1 , a housing 2, a single electrical motor M with a driving shaft 8, a turning unit 3 comprising an upper part 4 with a planar upper surface 7 and a connecting section 5 and a lower part (not illustrated in figure 4).

[0068] The turntable illustrated in figure 4 comprises a gear arrangement being a planetary gear system. As can be seen, the gear arrangement comprises a sun gear 36 arranged at the end of the driving shaft 8 of the electrical motor M. Thus, when the driving shaft 8 rotates, also the sun gear 36 rotates. The gear arrangement further comprises a planet carrier 37 arranged in fixed engagement with the connecting section 5 of the turning unit. As the planet carrier 37 are in fixed connection with the connecting section 5 of the turning unit, rotation of the planet carrier 37 causes a rotational movement of the turning unit 3.

[0069] The gear arrangement further comprises planet gears 38 arranged on the planet carrier 37. The planet gear 38 are in driving engagement with the sun gear 36. The planet gear 38 are enclosed by a ring gear 39. As can be seen in figure 4, the ring gear 38 comprises gears on both the inside of the ring and outside of the ring. The inside of the ring gear 39 is in driving engagement with the planet gears 38, and wherein the outside of the ring gear 39 is in driving engagement with two cylindrical gears 40.

[0070] Further, the cylindrical gears 40 illustrated in figure 4 comprises a shaft 41 having a ballscrew arrangement 42 at its second end. The ballscrew arrangement 42 is in driving engagement with a threaded nut 43 that is in fixed engagement with the connecting section 5 of the turning unit 3. When the ballscrew arrangement 42 rotates, the rotation causes a vertical movement of the turning unit 3.

[0071 ] In order to control the locking of either the planet carriers 37 or the ring gear 39, a solenoid Z is arranged in the gear arrangement.

[0072] In the embodiment illustrated in figure 4, the gear system comprising the planetary gear system and the turning unit 3 are arranged in such a manner that when the vertical movement of the turning unit 3 occurs as previously described, also the planetary gear system and the electrical motor M will be vertically displaced. [0073] Turning now to figure 5, illustrating another turntable 1 in accordance with an embodiment of the present disclosure. The turntable 1 illustrated in figure 5 comprises similarly to the embodiment illustrated in figure 1 , a housing 2, a single electrical motor M with a driving shaft 8, a turning unit 3 comprising an upper part 4 with a planar upper surface 7 and a connecting section 5 and a lower part (not illustrated in figure 5).

[0074] Similarly to the turntable illustrated in figure 4 , also the turntable illustrated in figure 5 comprises a gear arrangement being a planetary gear system. The gear arrangement comprises a sun gear 44 arranged at the end of the driving shaft 8 of electrical motor M. The gear arrangement further comprises a planet carrier 45 arranged in fixed engagement with the connecting section 5 of the turning unit 3. As the planet carrier 45 are in fixed connection with the connecting section 5 of the turning unit 3, rotation of the planet carrier 45 causes a rotational movement of the turning unit 3.

[0075] The gear arrangement further comprises planet gears 46 arranged on the planet carrier 45 and in driving engagement with the sun gear 4. The planet gear 46 are enclosed by a ringer gear 47. The inside of the ring gear 47 is in driving engagement with the planet gears 46.

[0076] In the embodiment illustrated in figure 5, the ring gear 47 is arranged in fixed engagement with an outer cylinder 48 surrounding the connecting section 5 of the turning unit 3. The outer cylinder 48 comprises an outside screw thread 49 in engagement with a nut 50 fixed to the housing 2 of the turntable 1 . The outer cylinder 48 rotates as a result of the rotation of the ring gear 47, the rotation of the outer cylinder 48 causes a vertical movement of the turning unit 3.

[0077] Similarly to the turntable illustrated in figure 4, also the turntable illustrated in figure 5 may comprise a solenoid (not illustrated) in order to control the locking of either the planet carrier 45 or the ring gear 47.

[0078] In the embodiment illustrated in figure 5, the gear system comprising the planetary gear system and the turning unit 3 are arranged in such a manner that when the vertical movement of the turning unit 3 occurs as previously described, also the planetary gear system and the electrical motor M will be vertically displaced.