Planetary gearbox having single-tooth sun gear having evoloid toothing

Abstract

Abstract The invention relates to a planetary gearbox, comprising a sun gear having one tooth, a ring gear, planet gears and a planet carrier, on which the planet gears are rotatably arranged, wherein the sun gear, the planet gears and the ring gear have evoloid toothing. The invention further relates to a multi-stage planetary gearbox assembly. The aim of the invention is to create a planetary gearbox of the type in question which enables high load capacity even at high transmission ratios. This aim is achieved, according to the invention, in that three circulating planet gears are provided in a frame- fixed ring gear, the planet gears not hitting each other even at high transmission ratios of i=24:1 because of defined addendum modification coefficients and addendum coefficients of the individual gears of the gearbox. Fig 4 Abstract The invention relates to a planetary gearbox, comprising a sun gear having one tooth, a ring gear, planet gears and a planet carrier, on which the planet gears are rotatably arranged, wherein the sun gear, the planet gears and the ring gear have evoloid toothing. The invention further relates to a multi-stage planetary gearbox assembly. The aim of the invention is to create a planetary gearbox of the type in question which enables high load capacity even at high transmission ratios. This aim is achieved, according to the invention, in that three circulating planet gears are provided in a frame- fixed ring gear, the planet gears not hitting each other even at high transmission ratios of i=24:1 because of defined addendum modification coefficients and addendum coefficients of the individual gears of the gearbox. Fig 4 20 25 20 25 00 09 A pr 2 02 5 A b s t r a c t 2 0 2 5 2 0 2 5 0 0 0 9 A p r 2 0 2 5 d e f i n e d a d d e n d u m m o d i f i c a t i o n c o e f f i c i e n t s a n d a d d e n d u m 4 / 8 4 / 8 Figure 4 15d 5d 9d 1d 2d 6d 14d 20 25 20 25 00 09 A pr 2 02 5 1 5 d 9 d 1 d 2 d 6 d 1 4 d 2 0 2 5 2 0 2 5 0 0 0 9 A p r 2 0 2 5

Description

Related Applications 5 This application is a divisional application of Australian patent application number 2019237104 which is the Australian National Phase of PCT / EP2019 / 056389 filed on 14 March 2019 which in turns claims priority from DE Patent Application No. 10 2018 107 021.7 dated 23 March 10  2018, whose specifications as originally filed are hereby incorporated by reference in their entirety. Field of the Invention The invention relates to a planetary gearbox comprising 15 a sun gear, a ring gear, planet gears and a planet carrier on which the planet gears are rotatably arranged, wherein the sun gear, the planet gears and the ring gear have evoloid toothing. Moreover, the invention relates to a multi-stage planetary gearbox arrangement. 20 Background to the Invention Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms 25 part of common general knowledge in the field. Planetary gearboxes have numerous advantages compared with other types of gearboxes, in particular: 30  -    a compact, heavy-duty design, -    supporting many teeth simultaneously, -    a relatively high transmission ratio in one stage and -    a multi-stage arrangement through the series 35        connection of multiple planetary gearboxes. A generic planetary gearbox with a high transmission ratio is known from WO 2008 / 079011 A1, said gearbox having two planet gears and a sun gear having one tooth 2025202500   25 Aug 2026 or two teeth, wherein the sun gear, the planet gears and the ring gear have evoloid toothing. The planet gears in this gearbox are frame-fixed and the output takes place via the ring gear. The transmission ratio is i=20:1. 5 The disadvantage of the planetary gearbox with a high transmission ratio known from WO 2008 / 079011 A1 is its lower load-bearing capacity compared with the widely used and preferred embodiment of planetary gearboxes with 10 three planet gears. Planetary gearboxes with three planetary gears have further advantages, in particular -    an improved distribution of load over a greater 15        number of planet gears, -    a uniform transmission of force in the planet carrier via the axes of the planet gears lying at the corner points of an equilateral triangle, and -    a centering of the sun gear relative to the ring 20        gear through the forces exerted by the planet gears. Fitting the planetary gearbox known from WO 2008 / 079011 A1 with three planet gears fails at anything above a transmission ratio of roughly i=12:1 because the planet 25 gears would strike and another and collide. It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior 30 art, or to provide a useful alternative. Summary of the Invention In a first aspect, the invention provides a planetary gearbox comprising 35        -    a sun gear, -    a ring gear, -    planet gears and -    a planet carrier on which the planet gears are rotatably arranged, 2025202500   25 Aug 2026 -    wherein the sun gear, the planet gears and the ring gear have evoloid toothing, wherein -    the planetary gearbox has three planet gears, 5        -    the ring gear is frame-fixed, -    the number of teeth of the sun gear is z=1, -    the positive addendum modification coefficient x of the sun gear falls within the range of 1.4 to 1.6, 10        -    the negative addendum modification coefficient x of each planet gear falls within the range of -0.2 to -0.4, -    the negative addendum modification coefficient x of the ring gear falls within the range 15 of -0.8 to -1.0, -    the addendum coefficient haPsg of the sun gear falls within the range of 0.1 to 0.2, -    the addendum height coefficient haPpg of the planet gear falls within the range of 0.5 to 0.7 and 20        -    the addendum factor haPrg of the ring gear falls within the range of 1.3 to 1.5. Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, 25 “comprising”, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”. 30 Advantageously, embodiments of the invention may provide a generic planetary gearbox with evoloid toothing which facilitates a high load-bearing capacity, even at high transmission ratios including i=24:1 in particular. 35 Embodiments of the invention are based on the principle of equipping a planetary gearbox with evoloid toothing with three rotating planet gears which do not strike one another, even at high transmission ratios. Specifically, 2025202500   25 Aug 2026 the problem is solved by a planetary gearbox having the features of claim 1. Advantageously, in embodiments of the invention the sun 5 gear comprising only one tooth contributes to the high possible transmission ratios. In order to reduce the planet gear diameter, a sharp addendum reduction and, in addition, a negative addendum 10 modification of the planet gears is proposed according to the invention. The negative addendum modification coefficient x of each planet gear falls within the range of -0.2 to -0.4. The addendum height coefficient haPpg of the planet gear falls within the range of 0.5 to 0.7. 15 At the same time, the sun gear receives a large positive addendum modification and addendum reduction, so that the diameter of the sun gear is greater. The positive addendum modification coefficient x of the sun gear falls within the range of 1.4 to 1.6. The addendum coefficient 20  haPsg of the sun gear falls within the range of 0.1 to 0.2. The number of teeth on the planet gears can be increased to up to 11  on account of  the addendum modification and addendum reduction of the sun gear. 25 The internally toothed, frame-fixed ring gear is subject to a negative addendum modification, as a result of which the used part of the toothing is displaced outwardly. The negative addendum modification coefficient x of the ring gear falls within the range of -0.8 to -1.0. The addendum 30 factor haPrg of the ring gear falls within the range of 1.3 to 1.5. The reference profile of customary gears is standardized in DIN 867. 35 A planetary gearbox according to embodiments the invention can transmit very high output torques with a very small installation space. A planetary gearbox 2025202500   25 Aug 2026 according to the invention has a diameter of roughly 65 mm and a modulus of 1.75 mm, for example. Advantageously, with a transmission ratio of i=24:1 and 5 an efficiency factor of 94%, the torque in the planetary gearbox is increased by a factor of 22.56. This factor cannot be achieved with planetary gearboxes known in the art. 10 In embodiments of the invention, each planetary gear mates with the ring gear via a first path of contact and with the sun gear via a second path of contact. If the operating angle of contact of the first path of contact coincides with the operating angle of contact of the 15 second path of contact, the efficiency factor of the planetary gearbox coincides, irrespective of whether the drive takes place via the sun or the planet carrier (web). In embodiments of the invention, the coinciding operating 20 angles of pressure are achieved through symmetrical configuration of the totals of the addendum modifications, i.e. the total addendum modifications for the sun gear and a planet gear corresponds in value terms to the total addendum modifications of a planet gear and 25 the ring gear. This choice of toothing parameters of the planetary gearbox means that the engagement of the mating teeth of the ring gear and the planet gears after the pitch point 30 and the engagement of the mating teeth of the sun gear and the planet gears before the pitch point, as can be seen for one of the planet gears in Figure 9. In embodiments of the invention, when the planetary 35 gearbox is driven by the sun gear, the fact that engagement takes place before the pitch point benefits the rotation of the planet gears through progressive (impacting) friction and the fact that the pitch point lies on the ring gear after engagement benefits the 2025202500   25 Aug 2026 running of the planet gears on the ring gear through degressive (dragging) friction. In embodiments of the invention, when the drive is on the 5 planet carrier (web), the fact that engagement takes place before the pitch point benefits the rotation of the sun gear on account of the progressive (impacting) friction and the fact that the pitch point lies on the ring gear after engagement benefits the running of the 10 planet gears on the ring gear through degressive (dragging) friction. The drive of the planetary gearbox according to embodiments of the invention customarily takes place via 15 the sun gear and the output via the planet carrier. A reversal of the output is entirely possible, however, and this may be relevant particularly to applications in the automobile industry, for example to body hatches and doors driven via a planetary gearbox. 20 Due to the small space requirement in a radial direction, the planet gears are rotatably mounted on the planet carrier, preferably by means of needle bearings. The sun gear has a low-friction toe bearing known from precision 25 engineering, which allows a reverse rotation of the planetary gearbox from the output side itself, even with very high transmission ratios in multi-stage planetary gearbox arrangements. 30 The angle of inclination of the evoloid toothing of the sun gear, of the planet gears, and of the ring gear preferably falls within a range of 30° to 40°. This angle of inclination produces a high transverse contact ratio of roughly 2 which produces good gearbox running 35 properties. The transmission ratio of the planetary gearbox according to the invention is obtained from 2025202500   25 Aug 2026 (zring gear / zsun gear)  + 1 where 5 i = transmission ratio z = number of teeth. For a standard transmission ratio of the planetary gearbox i = 24:1, the number of teeth on the planet gears 10 is z=11 and the number of teeth on the ring gear is z=23. With good lubrication and the use of suitable materials, a planetary gearbox of this kind has an efficiency factor of over 94%. 15 A two-stage gearbox arrangement comprising two planetary gearboxes where i=24:1 still has an efficiency factor of over 88% with a total transmission ratio of 576:1. A three-stage gearbox arrangement comprising three planetary gearboxes where i=24:1 still has an efficiency 20 factor of over 83% with a total transmission ratio of 13824:1. For a planetary gearbox transmission ratio of i = 6:1, the number of teeth on the planet gears is z=2 and the 25 number of teeth on the ring gear is z=5. The planetary gearbox where i=6:1 has the lowest transmission ratio that can be achieved with a sun gear where z=1 and a uniform arrangement of three planet gears. 30 The planetary gearbox where i=6:1 may be enlarged to a module of up to 5.5 mm. This increases the load-bearing capacity of the gearbox. Between this lowest transmission ratio i=6:1 and the 35 standard ratio i=24:1, planetary gearboxes with the transmission ratio i = 12:1 can be realized, wherein the number of teeth of the planetary gears is z=5 and the number of teeth of the ring gear is z=11, or with the transmission ratio i = 18:1, wherein the number of teeth 2025202500   25 Aug 2026 of the planetary gears is z=8 and the number of teeth of the ring gear is z=17. The dimensions, in particular the connection dimensions 5 of the planetary gearboxes, preferably coincide irrespective of the selected transmission ratio. This allows a multi-stage planetary gearbox arrangement made up of planetary gearboxes with the same and / or different transmission ratios to be of modular composition. 10 Insofar as the planet gears of the first stage, at least, are not made of steel but of plastic, this reduces the noise generated by the gearbox. The remaining gears are made of steel. 15 The drive of the sun gear in each planetary gearbox takes place via a drive shaft, wherein all drive shafts in the different stages of the planetary gearbox arrangement are aligned with one another. The torque transmission between 20 the individual stages takes place via an Oldham coupling, wherein a spring is arranged on a first coupling part and a spring is arranged on a second coupling part, which springs engage with intersecting grooves in a coupling disc. One of the two springs is preferably arranged on 25 the front side of the drive shaft of the sun gear and one spring is arranged on the planet carrier of the preceding stage. The Oldham coupling, also referred to as a Kreuzschlitzkupplung (cross-recess coupling) in the German-speaking area, is a non-switchable, torsionally 30 rigid coupling which can compensate a radial offset of two parallel shafts. With a planetary gearbox or a multi-stage planetary gear arrangement comprising up to three planetary gearboxes 35 according to the invention which preferably have one of the aforementioned transmission ratios i=6:1, 12:1, 18:1, 24:1, virtually all total transmission ratios from i=6:1 to i=13848:1 can be realized with a step range of 6 according to the arithmetical number sequence. 2025202500   25 Aug 2026 Tests with planetary gearbox arrangements having two stages with a transmission ratio of i=24:1 in each case, in other words a total transmission ratio of i=576:1, 5 could be turned back relatively easily with the nonenergized drive motor on the drive side from the output side. Brief Description of the Drawings 10 The invention is explained in greater detail below with the help of the figures. In the figures 15 Figure 1 shows an exploded view of a planetary gearbox according to the invention with a transmission ratio of i=24:1, Figure 2 shows a longitudinal section through a two-stage planetary gearbox arrangement, 20 Figure 3 shows  a  longitudinal  section  through  a planetary gearbox according to Figure 1, 25 Figure 4 shows an exploded view of a further exemplary embodiment of a planetary gearbox according to the invention with a transmission ratio of i=6:1, 30 Figure 5 shows a ring gear, a planet gear and a sun gear of a planetary gearbox according to Figure 4, Figure 6 shows a ring gear of a planetary gearbox according to Figure 1, 35 Figure 7 shows a planet gear made of plastic for a planetary gearbox according to Figure 1, Figure 8 shows a sun gear for a gearbox according to the invention with a drive shaft, and 2025202500   25 Aug 2026 Figure 9    shows a representation intended to illustrate the operating angle of contact between the planet gears and the ring gear, on the one 5               hand, and the planet gears and the sun gear, on the other, of a planetary gearbox according to the invention. Preferred Embodiments of the Invention 10 The planetary gearbox according to Figure 1 comprises a sun gear (2a), a frame-fixed ring gear (1a), three planet gears (8a), and a planet gear (4a). The ring gear (1a) is depicted in detail in Figure 6, the planet gear (8a) in detail in Figure 7, and the sun gear (2a) in detail 15 in Figure 8. The sun gear (2a) comprising only one tooth is arranged on the drive shaft in a non-rotatable manner and mates with the three planet gears (8a) which each have eleven teeth. In the exemplary embodiment shown, the planet gears (8a) are produced from plastic in order to 20 reduce noise. Each planet gear (8a) is mounted rotatably via a bearing (9a) about a cylindrical pin (11a). The cylindrical pins extend between two planet carrier discs (5a, 6a) of the 25 planet carrier (4a) arranged in parallel spaced apart from one another. The cylindrical pins (11a) projecting beyond the planet gears (8a) on both sides engage with receiving openings aligned with one another in the planet carrier discs (5a, 6a). 30 The two planet carrier discs (5a,  6a) of the planet carrier (4a) are, moreover, held spaced apart by hollow support parts (3a). The hollow support parts (3a) are hollow-cylindrical and have internal threads on both 35 sides for receiving screws (12a). Through corresponding bores in the planet carrier discs (5a, 6a) of the planet carrier, the screws (12a) engage through the planet carrier disc into the internal thread of the hollow support parts (3a). 2025202500   25 Aug 2026 The planet carrier disc (6a) on the drive side has a central bore for receiving a bearing sleeve (13a) which supports the drive shaft of the sun gear (2a) rotatably 5 in the lower planet carrier disc (6a). The drive of the planetary gearbox takes place via an Oldham coupling comprising a coupling disc (7a) with two intersecting grooves on opposite sides of the coupling 10 disc. A spring which engages with the groove introduced on the upper side of the coupling disc (7a) is formed on the front side of the drive shaft of the sun gear (2a). A drive shaft of a motor (1b) not shown in Figure 1 exhibiting a spring likewise formed on the front side 15 engages with the opposite groove of the coupling disc (7a) (cf. Figure 2). The planet carrier (4a) is rotatably mounted in the frame-fixed ring gear (1a). On the outer casing of the 20 ring gear (1a), three holders are arranged over the circumference offset by 120 degrees in respect of one another, said holders each having passages for receiving screws, in order to mechanically connect to one another multiple planetary gearboxes with corresponding 25 dimensions and connection measurements in a multi-stage planetary gearbox arrangement. The passages in the holders extend in the longitudinal direction of the planetary gearbox and also parallel to the rotational axes of the gears of each planetary gearbox lying in a 30 plane. Figure 2 shows a two-stage planetary gearbox arrangement which is made up of two planetary gearboxes according to Figure 1, as follows: 35 The electric motor (1b) is connected to the first planetary stage (5b) on the front side via a motor adapter (3b). The motor adapter (3b) likewise has holders which are each offset in respect of one another by 120 degrees 2025202500   25 Aug 2026 and which each have a passage for a screw. The passages in the three holders of the motor adapter (3b) are aligned with the passages in the holders of the ring gear (1a). 5 Behind the first planetary gear stage (5b) is located an adapter (4b) which is arranged between the first planetary gear stage (5b) and the second planetary gear stage (5b). By means of the adapter (4b), the necessary space is created between the stages, in order to couple 10 the output of the planetary gearbox of the first stage with the drive of the planetary gearbox in the second stage. The coupling takes place via an Oldham coupling which comprises a coupling disc (7a). The coupling disc (7a) coincides with the coupling disc (7a) which couples 15 the motor (1b) with the drive shaft of the sun gear (2a) of the first stage. The planet carrier disc (5a) on the output side (cf. Figure 1) of the planetary gearbox in the first stage has 20 a spring on its outwardly facing surface which engages with one of the two grooves in the coupling disc (7a). The spring of the drive shaft of the sun gear (2a) of the second stage formed on the front side of the drive shaft engages with the groove formed on the opposite side of 25 the coupling disc (7a). The spring of the drive shaft of the second stage formed on the front side corresponds geometrically with the spring of the drive shaft of the first stage formed on 30 the front side. The planet carrier disc of the planetary gearbox on the output side in the second stage has on its outwardly facing surface a spring corresponding geometrically to the spring of the first gear stage. On account of the preferably geometrically completely 35 corresponding drives and outputs of all planetary stages and the geometrically corresponding frame-fixed housing (sun gear) including the holders, multiple planetary gearboxes with the same and / or different transmission ratios according to the invention can be connected in 2025202500   25 Aug 2026 series in a multi-stage planetary gearbox arrangement according to Figure 2. An end cover, whereof holders (6b) arranged on the 5 circumference correspond to the holders on the ring gears of the two planetary stages (5b), to holders on the motor adapter (3b) and to holders on adapters (4b) arranged between the two planetary stages (5b) is located at the output of the second planetary stage (5b). The passages 10 in each of the three corresponding holders are aligned with one another, in order to receive screws (9b). The end cover has a passage in the center, through which an output carrier (7b) extends which is fastened to the 15 planet carrier of the second stage on the output side by means of screws (11b). The output torques of the planetary gearbox arrangement are transmitted to the output carriers (7b), in that the spring on the output side of the planet carrier disc (5a) engages with a groove 20 in the output carrier (7b). The motor, the two planetary stages and the adapters arranged therebetween and the end cover of the planetary gear arrangement are connected to three screws (9b). The 25 three screws (9b) pass through the passages aligned with one another in the holders (6b) starting from the end cover and are secured at the opposite motor adapter by nuts (10b). 30 Figure 3 shows a section through a planetary gearbox corresponding to Figure 1. The same components are provided with the same numbers but with different letters. 35 In particular, the arrangement of the drive shaft of the sun gear (2c) can be identified from the sectional representation. On the drive side, the drive shaft is mounted by means of a bearing sleeve (13c) in the planet carrier disc (6c) of the planet carrier (4c). On the 2025202500   25 Aug 2026 output side, the drive shaft is mounted in a toe bearing (10c) in the planet carrier disc (5c) on the output side. Figure 4 shows in conjunction with Figure 5 an exploded 5 view of a planetary gearbox according to the invention having a transmission ratio of i=1:6. Corresponding components, as in the exemplary embodiment according to Figure 1, are identified using corresponding numbers but different letters. The sun gear (2d) sits on a drive 10 shaft, the drive-side portion whereof extends through the drive-side planet carrier disc (6d) and is connected in a non-rotatable manner to a motor which is not shown, for example. The shaft portion projecting beyond the sun gear (2d) on the output side is mounted in a rotatable manner 15 in a central bore of the planet carrier disc (5d) on the output side. The planet gears likewise each have shaft stubs on both sides of the planet gear which are received in 20 corresponding bearings in the planet carrier disc (6d) on the drive side and the planet carrier disc (5d) on the output side. The ring gear (1d) has a circumferential web on both front sides of the inner toothing, on which web the planet carrier disc (5d, 6d) on the drive side or the 25 output side is rotatably mounted. In an axial direction of the planetary gearbox, the planet carrier discs (5d, 6d) are each secured between one of the two circumferential webs and a cover (14d,  15d). The fastening of the two covers (14d, 15d) to the frame-fixed 30 ring gear (1d) takes place via the holders fastened to the outer casing of the ring gear, the passages of which are aligned with corresponding passages on holders of the two covers (14d,  15d). The passages serve to receive screws which are not shown in Figure 4 and which connect 35 the two covers to the ring gear. The output may take place, for example, through a pin inserted in a non-rotatable manner into the central bore in the planet carrier disc (5d). 2025202500   25 Aug 2026 An optimally toothed planetary gearbox according to the present invention exhibits a positive addendum modification coefficient of +1.52 for the sun gear, a negative addendum modification coefficient of -0.32 for 5 the planet gears, a negative addendum modification coefficient of -0.88 for the ring gear, and an addendum coefficient for the sun gear of 0.165 haPsg, an addendum coefficient of 0.672 haPpg for the planet gear, and an addendum coefficient of 1.391 haPrg for the ring gear. The 10 angle of inclination of the evoloid toothing of all gears is roughly 36 degrees. 2025202500   25 Aug 2026 List of reference numbers Figure 1 Figure 3 1a Ring gear 1c Ring gear 2a Sun gear 2c Sun gear 3a Hollow support part 3c Hollow support part 4a Planet carrier 4c Planet carrier 5a Planet carrier disc 5c Planet carrier disc 6a Planet carrier disc 6c Planet carrier disc 7a Coupling disc 7c Coupling disc 8a Planet gear 8c Planet gear 9a Planet gear bearing 9c Planet gear bearing 10a Bearing 10c Sun gear toe bearing 11a Cylindrical pin 11c Cylindrical pin 12a Screw 12c Screw 13a Bearing sleeve 13c Bearing sleeve Figure 2 Figure 4 1b Motor 1d Ring gear 2b Oldham coupling 2d Sun gear 3b Motor adapter 5d Planet carrier disc 4b Adapter 6d Planet carrier disc 5b Planetary stage 9d Planet gear 6b Adapter holder 14d Cover 7b Output carrier 15d Cover 9b Screw 10b Nut 11b Screw

Claims

1. A planetary gearbox comprising -    a sun gear,5        -    a ring gear,-    planet gears and-    a planet carrier on which the planet gearsare rotatably arranged,-    wherein the sun gear, the planet gears and10 the ring gear have evoloid toothing, wherein-    the planetary gearbox has three planet gears,-    the ring gear is frame-fixed,-    the number of teeth of the sun gear is z=1,15        -    the positive addendum modificationcoefficient x of the sun gear falls within the range of1.4 to 1.6,-    the negative addendum modificationcoefficient x of each planet gear falls within the20 range of -0.2 to -0.4,-    the negative addendum modificationcoefficient x of the ring gear falls within the rangeof -0.8 to -1.0,-    the addendum coefficient haPsg of the sun gear25 falls within the range of 0.1 to 0.2,-    the addendum height coefficient haPpg of theplanet gear falls within the range of 0.5 to 0.7 and-    the addendum factor haPrg of the ring gearfalls within the range of 1.3 to 1.5.30  2. The planetary gearbox as claimed in claim 1,wherein-    the planetary gears mate with the ring gearvia a first path of contact and with the sun gear via a second path of contact and35        -    the operating angle of contact of the firstpath of contact coincides with the operating angle ofcontact of the second path of contact.2025202500   25 Aug 20263. The planetary gearbox as claimed in claim 1, wherein the planet gears are rotatably mounted on the planet carrier by means of needle bearings.

4. The planetary gearbox as claimed in one of claims 5   1 to 3, wherein the angle of inclination of the evoloidtoothing of the sun gear, of the planet gears, and of the ring gear coincides and falls within a range of 30°to 40°.

5. The planetary gearbox as claimed in one of claims10   1 to 4, wherein the transmission ratio of the planetarygearbox is i = 6:1, wherein the number of teeth on theplanet gears is z=2 and the number of teeth on the ringgear is z=5.

6. The planetary gearbox as claimed in one of claims 15   1 to 4, wherein the transmission ratio of the planetarygearbox is i = 12:1, wherein the number of teeth of theplanetary gears is z=5 and the number of teeth of the ring gear is z=11,7. The planetary gearbox as claimed in one of claims 20   1 to 4, characterized in that the transmission ratio ofthe planetary gearbox is i = 18:1, wherein the numberof teeth of the planetary gears is z=8 and the numberof teeth of the ring gear is z=17.

8. The planetary gearbox as claimed in one of claims 25   1 to 4, wherein the transmission ratio of the planetarygearbox is i = 24:1, wherein the number of teeth on theplanet gears is z=11 and the number of teeth on thering gear is z-23.

9. A multi-stage planetary gearbox arrangement30 comprising at least two planetary gearboxes as claimed in one of claims 1 to 8.

10. The multi-stage planetary gearbox arrangement as claimed in claim 9, wherein the drive of each planetary2025202500   25 Aug 2026gearbox takes place via the sun gear and the output via the planet carrier.

11. The multi-stage planetary gearbox arrangement asclaimed in claim 10, wherein the drive of the sun gear5 in each planetary gearbox takes place via a drive shaft and all drive shafts are aligned with one another.

12. The multi-stage planetary gearbox arrangement asclaimed in claim 11, wherein the planetary gearboxesare connected to one another via an Oldham coupling.10  13. The multi-stage planetary gearbox arrangement asclaimed in claim 11, wherein-    with each planetary gearbox, a spring isarranged in a non-rotatable manner on the drive shaftof the sun gear on the front side and a spring is15 arranged in a non-rotatable manner on an output side of the planet carrier,-    the Oldham coupling comprises a coupling discwith two intersecting grooves on opposite sides of the coupling disc,20        -    wherein the spring of a drive shaft and thespring of a planet carrier of planetary gearboxes to be coupled to one another engage with the intersecting grooves.

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