Shifting device for a transmission mechanism and a transmission mechanism having such a shifting device

Abstract

The present invention relates to a shifting device for a transmission mechanism and a transmission mechanism having such a shifting device. Specifically, the shifting device is for a transmission mechanism having a first transmission mechanism housing part and a second transmission mechanism housing part. The shifting device includes a shift sleeve, a shift fork engaged with the shift sleeve, an adjustment actuator disposed in the first transmission mechanism housing part, and an adjustment rod connected at one end to the adjustment actuator and at the other end to the shift fork, wherein the adjustment rod is supported in a first guide hole formed in the first transmission mechanism housing part. A second guide hole formed parallel to the first guide hole in the first transmission mechanism housing part is proposed, and a guide rod oriented parallel to the adjustment rod is provided, wherein one end of the guide rod is connected to the shift fork and the other end is supported in the second guide hole. Furthermore, a transmission mechanism having such a shifting device is proposed.

Description

Technical Field

[0001] The present invention relates to a shifting device for a transmission having a first transmission housing part and a second transmission housing part, and a transmission having such a shifting device. The shifting device comprises a shift sleeve, a shift fork engaged in the shift sleeve, an adjustment actuator arranged in the first transmission housing part, and an adjustment rod connected at one end to the adjustment actuator and at the other end to the shift fork, wherein the adjustment rod is supported in a first guide bore formed in the first transmission housing part. Background Art

[0002] Such shifting devices are known and are used, for example, in agricultural vehicles, particularly tractors or harvesting machines such as combine harvesters or forage harvesters. In particular, in such combine harvesters, the transmission is equipped with such a shifting device to enable the transmission's output rotational direction to be switched from a first rotational direction to a second, opposite rotational direction. In principle, the reverse rotational direction (i.e., drive reversal) is only set in exceptional circumstances, such as in the event of a blockage in the harvesting table of the combine harvester and / or in the crop conveyor in the conveyor duct. The shifting device is generally configured such that a shift sleeve is connected to a shift fork, which is displaceable by a hydraulically actuated adjusting cylinder. To this end, the shift fork is fastened to an adjusting rod connected to the adjusting cylinder. The adjusting rod is axially displaceably supported in guide holes arranged in opposing housing halves of the shifting device. The shift fork is arranged between the guide holes to minimize the shifting torque acting on the adjusting rod when the shift sleeve is displaced. This arrangement of the shift fork, adjusting rod, and guide bore in the two housing halves compromises the compactness of the shifting device and requires a relatively large amount of structural space. Furthermore, the shift fork is typically connected to the adjusting rod only at its outer portion. Consequently, when the adjusting force required to shift the shift sleeve is applied, relatively large bending moments act on the shift fork and adjusting rod. Furthermore, due to the only point-like connection, the shift fork can also have a certain amount of rotational play relative to the adjusting rod. Consequently, the fork legs of the shift fork can disadvantageously load the shift sleeve in the radial direction, which in particular leads to friction losses. Summary of the Invention

[0003] The object on which the present invention is based is considered to be to provide a shifting device and a transmission of the type mentioned in the introduction, with which the aforementioned disadvantages can be overcome.

[0004] It is proposed to design a shifting device of the type mentioned at the outset so that a second guide hole is arranged in the first transmission housing part, formed parallel to the first guide hole, and a guide rod is provided, oriented parallel to the adjusting rod, one end of the guide rod being connected to the shift fork and the other end being supported in the second guide hole. This arrangement is particularly suitable for transmissions requiring limited installation space, in which the arrangement of a second guide hole for the adjusting rod in the second transmission housing part (as opposed to the first guide hole in the first transmission housing part) could compromise the compactness of the transmission. The arrangement of the second guide hole for the adjusting rod parallel to the first guide hole and the arrangement of the guide rod supported in the second guide hole avoids the need for a guide hole for the adjusting rod in the second transmission housing part. The first transmission housing part remains virtually unchanged in its overall depth, while the second transmission housing part can be designed with a smaller overall depth, thereby achieving a smaller overall installation space. Furthermore, the shift fork is supported by the adjusting rod and the guide rod in such a way that the shift fork is held concentrically with the shift sleeve, avoiding rotational play of the shift fork relative to the adjusting rod and, therefore, the associated friction losses between the shift fork and the shift sleeve. This reduces wear on the shift fork and the shift sleeve. Furthermore, the additional connection point between the shift fork and the guide rod, which forms a support point for the shift fork relative to the adjusting rod, minimizes the bending moments acting on the shift fork and the adjusting rod during displacement of the shift sleeve, thereby facilitating the shifting process.

[0005] The first guide bore is preferably formed between the adjustment actuator and the shift fork. As a result, the guide bore can be advantageously formed as an integral component of the first transmission housing part in terms of construction technology.

[0006] To ensure a gear position in the preferred direction, at least one first spring element may be provided that pushes the shift fork in the corresponding preferred direction. If the actuating force exerted by the actuating actuator on the actuating rod fails (e.g., due to a malfunction or defect in the actuating actuator), the actuating force exerted by the spring element pushes the shift fork in the preferred direction and maintains the corresponding gear position generated in the given preferred direction. The actuating actuator may, for example, be a hydraulically actuated actuating cylinder having an actuating piston connected to the actuating rod. In the event of a hydraulic system failure, the actuating force exerted by the actuating actuator may fail, so that the force exerted by the spring element serves as the sole actuating force in the preferred direction. Alternatively, the actuating actuator may be electrically driven, so that in the event of an electrical failure, no actuating force is exerted by the actuating actuator on the actuating rod, and the force exerted by the spring element also serves as the sole actuating force in the preferred direction. The preferred direction may, for example, be the shift direction in which the shift sleeve must be moved to drive the harvesting deck for receiving the crop. The shifting direction opposite to the preferred direction can then be, for example, a shifting direction in which the shift sleeve must be moved in order to achieve a drive reversal with a reversed direction of rotation, for example in the event that the harvesting table and / or the crop conveying device in the conveying channel of the combine harvester are blocked or obstructed.

[0007] The spring element is preferably arranged between the first transmission housing part and the shift fork. Alternatively, however, the spring element can also be arranged in the actuating actuator and exert an actuating force, for example, on an actuating piston. In the event of a malfunction in the hydraulic system or the electrical system, the actuating force in the preferred direction can be maintained on the actuating piston due to the spring element.

[0008] The spring element is preferably designed as a compression spring and extends at least partially into a spring guide bore formed in the first transmission housing part parallel to the first and second guide bores. The compression spring exerts an actuating force on the shift fork, which moves or presses the shift fork toward the second transmission housing part. The spring guide bore serves, on the one hand, to prevent the compression spring, which is designed, for example, as a coil spring, from kinking. On the other hand, it also serves as an assembly aid by facilitating the insertion and assembly of the spring element.

[0009] In addition to the single or first spring element, a second or additional spring element may also be provided. The number and size of the spring elements can vary depending on the installation space and the required actuating force. Advantageously, the installation space between the shift fork and the first transmission housing part allows for the placement of multiple spring elements. This has the advantage that the actuating force originating from the spring elements can be designed to be highly variable. The spring elements for generating the actuating force in the preferred direction are typically arranged within the actuating actuator itself, for example, using compression springs arranged in the hydraulic chamber of the actuating piston. However, this arrangement is limited by the design and size of the actuating actuator. An equal number of spring elements are preferably provided on both sides of the guide rod to prevent torque from acting on the guide rod and the actuating rod. In a preferred embodiment, two compression springs, designed as coil springs, are arranged on either side of the guide rod. The spring guide bore in the first transmission housing part extends parallel to the second guide bore. The compression springs and spring guide bore are arranged so that they engage both sides of the shift fork. The compression spring is dimensioned so that, even when the actuating force is absent or disabled, a sufficiently large actuating force is still applied to the hydraulically driven actuating actuator by the compression spring, so that the actuating fork and the shift sleeve move in the preferred direction and the shift sleeve remains in the preferred gear position. This ensures that the drive connection to the harvesting deck remains established and that the user does not have to interrupt their harvesting work or can continue their harvesting work even in the event of a hydraulic system failure.

[0010] A transmission equipped with the above-described shifting device preferably has a second transmission housing portion connected to the first transmission housing portion. An output shaft extends through the first and second transmission housing portions. The first drive element of the transmission can be connected to the output shaft via a planetary gear set. Furthermore, a second drive element can be connected to the output shaft. The transmission also has a gear that is rotationally fixedly connected to the output shaft and engages with a shift sleeve. In first gear, the shift sleeve engages with the planetary gear set and the gear; and in second gear, the shift sleeve engages with the second drive element and the gear.

[0011] Preferably, the first gear, in which the shift sleeve comes into engagement with the planetary gear set, is the gear in the preferred direction or the gear for the normal operating mode of the combine harvester.

[0012] The planetary gearset includes a ring gear disposed on the second transmission housing portion, a set of planets rolling within the ring gear, a planet carrier capable of engaging with the shift sleeve in the first gear position, and a sun gear connected to the first drive element and rolling with the planet gears. Thus, in the first gear position, the drive flow from the first drive element passes through the sun gear and the planets rolling within the ring gear to the planet carrier, and from there via the shift sleeve to the gears of the output shaft. In the second gear position, the drive flow from the second drive element passes through the shift sleeve to the gears of the output shaft. In the first gear position, the direction of rotation of the drive shaft is opposite to that of the drive shaft in the second gear position. In the second gear position, the transmission is driven in reverse mode if, for example, the harvesting deck and / or the crop conveyor in the conveyor duct of the combine harvester are blocked or obstructed.

[0013] The first drive element is used in a normal operating mode of the harvester with a first rotational direction, in which the harvesting table and the crop conveyor are driven to collect the crop. The first drive element can be formed as a belt drive drum connected to the sun gear via a flange connection. The belt drive drum is preferably sized and designed such that the transmission mechanism itself is substantially located within the cavity enclosed by the belt drive disc.

[0014] The second drive element is used for a reverse operating mode of the harvester with a second, opposite direction of rotation. In this second direction of rotation, the harvesting table and the crop conveyor are driven in the opposite direction, for example, to clear any blockages or jams in the harvesting table and / or the crop conveyor. The second drive element is designed as a worm gear and is connected to the worm gear of the transmission. Alternatively, other drive types for the reverse operating mode may be selected, such as spur gears, hypoid gears, bevel gears, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The invention as well as further advantages and advantageous refinements and embodiments of the invention are described and explained in detail below with reference to the accompanying drawings which show exemplary embodiments of the invention.

[0016] In the attached figure:

[0017] Figure 1 A schematic side view of a harvesting machine in the form of a combine harvester with a harvesting deck and a charging device located on a conveyor path is shown.

[0018] Figure 2 Shown from Figure 1 Schematic perspective side view of a conveyor duct with a belt drive, a crop conveyor device, and a transmission for driving a harvesting deck and the crop conveyor device.

[0019] Figure 3 Shown from Figure 1 and Figure 2 An enlarged perspective front view of the transmission mechanism,

[0020] Figure 4 Shown from Figure 1 and Figure 2 An enlarged perspective rear view of the transmission mechanism,

[0021] Figure 5 The first section plane for the first gear shows the Figure 1 and Figure 2 An enlarged cross-sectional view of the transmission mechanism,

[0022] Figure 6 The first section plane for the second gear shows the Figure 1 and Figure 2 An enlarged cross-sectional view of the transmission mechanism,

[0023] Figure 7 The second section plane shows the Figure 1 and Figure 2 Another enlarged cross-sectional view of the transmission mechanism,

[0024] Figure 8 The third section plane for the first gear shows the Figure 1 and Figure 2 A perspective cross-sectional view of the transmission mechanism. DETAILED DESCRIPTION

[0025] Figure 1 A self-propelled agricultural machine 10 is shown, which is designed as a combine harvester by way of example. It is also conceivable that the embodiments described further below can also be designed on other self-propelled agricultural machines (e.g., forage harvesters, harvesters, sugarcane harvesters, or balers).

[0026] The agricultural machine 10 has a machine housing 12 and a processing device in the form of a threshing device 14, which has an axial rotor oriented in the longitudinal direction of the agricultural machine 10. The agricultural machine 10 is also provided with a harvesting table 16, which is connected to a conveying channel 18 (see also Figure 2 ). The agricultural machine 10 is driven by a combustion engine (not shown), from which in particular a belt drive 20 is branched, which is arranged on the conveyor duct 18. The belt drive 20 drives a first drive element 22 in the form of a belt-driven drum, which serves as a drive element of a transmission 24 for driving the harvesting deck 16 in normal operating mode and for driving a crop conveyor device 26 arranged in the conveyor duct.

[0027] exist Figures 3 to 8 The transmission 24 is shown in detail in FIG. 1 and comprises (in addition to the first drive element 22 formed as a belt drive drum) a first transmission housing part 28 and a second transmission housing part 30. A cylindrical rotor 32 (supported by means of a ball bearing 34) is arranged in the second transmission housing part 30. The rotor 32 is screwed to the first drive element 22 (the belt drive drum) at a first end 36 and is connected in a rotationally fixed manner. At the second end 38 of the rotor 32, a sun gear 40 of a planetary gear set 42 is connected in a rotationally fixed manner to the rotor 32. The sun gear 40 engages with a planetary set 44 of the planetary gear set 42. The planetary set rolls in a ring gear 46 embedded in the second transmission housing part 30. The planetary set 44 is supported on a planet carrier 48 that can engage with a shifting device 50.

[0028] The shifting device 50 comprises, in particular, a shift sleeve 52, a shift fork 54 engaged in the shift sleeve 52, an adjusting actuator 56 arranged in the first transmission housing part 28, and an adjusting rod 58 connected at one end to the adjusting actuator 56 and at the other end to the shift fork 54. The adjusting rod is supported in a first guide bore 60 formed in the first transmission housing part 28. Furthermore, a second guide bore 62 is formed in the first transmission housing part 28 parallel to the first guide bore 60. A guide rod 63 is arranged in the second guide bore 62 (arranged parallel to the adjusting rod 58). The guide rod is likewise connected at one end to the shift fork 54 and at the other end supported in the second guide bore 62.

[0029] The above-described arrangement of the shifting device 50 is particularly suitable for a transmission 24 requiring minimal space and having a compact design. In this arrangement, a second guide bore 62 for the adjusting rod 58 is also formed in the first transmission housing part 28. By arranging the second guide bore 62 for the adjusting rod 58 parallel to the first guide bore 60, in conjunction with the guide rod 63 supported in the second guide bore 62, a second guide bore for the adjusting rod 58 in the second transmission housing part 30 is avoided. Nevertheless, the overall depth of the first transmission housing part 28 remains virtually unchanged, while the second transmission housing part 30 can be designed with a relatively small overall depth, thereby achieving an overall smaller overall space. Furthermore, the shift fork 54 is supported by the adjusting rod 58 and the guide rod 63 in such a way that the shift fork 54 is held concentrically with the shift sleeve 52, avoiding rotational play of the shift fork 54 relative to the adjusting rod 58 and, therefore, friction losses associated with rotational play between the shift fork 54 and the shift sleeve 52. This reduces the wear on the shift fork 54 and the shift sleeve 52. Furthermore, the connection of the guide rod 63 to the shift fork 54 provides a support point relative to the adjustment rod 58, which minimizes the bending moments acting on the shift fork 54 and the adjustment rod 58 when the shift sleeve 52 is displaced, thereby facilitating the shifting process.

[0030] The regulating actuator 56 is formed as a double-acting hydraulic cylinder having a first pressure chamber and a second pressure chamber 64, 66 separated from each other by a regulating piston 68. The first pressure chamber 64 is located at Figure 5 and Figure 6 The transmission mechanism shown in FIG is formed on the left side of the regulating piston 68. The second pressure chamber 66 is just Figure 5 and Figure 6 The transmission mechanism shown in FIG is formed on the right side of the regulating piston 68. The regulating piston 68 is connected to the regulating rod 58. According to the filling of the first pressure chamber or the second pressure chamber 64, 66, the regulating piston 68 is moved to the first gear (see FIG. Figure 5 and Figure 8 ) or to the second gear (see Figure 6 )sports.

[0031] As in Figure 8As shown in FIG, first and second spring elements 70, 72, each designed as a compression spring, are arranged in the first transmission housing part 28, laterally of the guide rod 63. To guide and retain the spring elements 70, 72, first and second spring guide holes 74, 76 are arranged in the first transmission housing part 28, into which the respective spring elements 70, 72 partially extend. The spring elements 70, 72 are retained at a first spring end 78 in the respective spring guide holes 74, 76 and at a second spring end 80 in the respective first and second engagement holes 82, 84 arranged on the shift fork 54. The spring elements 70 , 72 therefore extend between them starting from the first transmission housing part 28 in the direction of the shift fork 54 and exert a clamping force in the direction of the second transmission housing part 30 , wherein the spring elements 70 , 72 push the shift fork 54 into the first gear or, when the pressure chambers 64 , 66 of the adjustment actuator 56 are depressurized, hold the shift fork 54 and therefore also the shift sleeve 52 in the first gear.

[0032] The shift sleeve 52 has an internal toothing 86 and is supported with this internal toothing (displaceable axially relative to the output shaft 86 on the gearwheel 90) on a gearwheel 90 which is connected in a rotationally fixed manner to the output shaft 88. Figure 5 and Figure 8 As can be seen in FIG, the shift sleeve 52 is half engaged with the planet carrier 48 and half engaged with the gear 90 in the first gear. Due to the axial displacement of the shift sleeve 52, this shift sleeve can be disengaged from the planet carrier 48 and brought into the second gear, as shown in FIG. Figure 6 In this second gear, the shift sleeve 52 is halfway to the gear in the form of a worm gear arranged on the output shaft 88 (see also Figure 7 and Figure 8 ) is engaged with the second drive element 94 and the other half is engaged with the gear 90. The second drive element 92 in the form of a worm gear is in driving connection with the transmission worm 94 and is supported on the output shaft 88 by means of a ball bearing 96.

[0033] The output shaft 88 is supported on the first transmission housing part 28 by means of a first rolling bearing 98 and on the rotor 32 by means of a second rolling bearing 100. The output shaft 88 extends over its length through the first and second transmission housing parts 28, 30 and has a first driven connection 102 at the output end of the second transmission housing part 30 and a second driven connection 104 at the output end of the first transmission housing part 28, wherein the first driven connection 102 is provided for connection to the harvesting deck 16 and the second driven connection 104 is provided for connection to the crop conveying device 26.

[0034] As can be seen in the figure, the belt drive drum is shaped in a convex manner so that it completely surrounds the second transmission housing part 30 and at least partially surrounds the first transmission housing part. This ensures a compact design of the transmission 24.

[0035] The second drive element 92 is driven by an electric motor 106, which is held by a holder 108 arranged on the first transmission housing part 28. This electric motor is used to drive the second drive element 92 in the reverse operating mode, for example, when the harvesting deck or the crop conveyor is blocked or jammed. In the reverse operating mode, the shift sleeve 52 is engaged in the second gear or brought into engagement with the gear wheel 90 and the second drive element 92, the drive to the first drive element (belt drive drum) being decoupled, and the aforementioned arrangement of the various transmission components results in a direction of rotation of the output shaft 88 opposite to that in the normal operating mode.

[0036] The spring elements 70, 72 described above are used to ensure an actuating force in a preferred direction, which ensures the gear position for the normal operating mode of the agricultural machine 10 if the hydraulic supply to the actuating actuator 56 fails. In addition to the spring elements 70, 72 shown, additional spring elements and corresponding spring guide holes, or larger spring elements and spring guide holes, can be provided to achieve greater actuating forces. The number and size of the spring elements 70, 72 can be varied depending on the installation space and the required actuating force. The spring elements 70, 72 and spring guide holes 74, 76 are arranged so that they engage under stress in the engagement holes 82, 84 on both sides of the shift fork. The spring elements 70, 72 are dimensioned so that, even when there is no actuating force on the hydraulically driven actuating actuator 56 or when the actuating force is disabled, a sufficiently large actuating force is still applied to the shift fork 54 by the spring elements 70, 72, so that the shift fork 54 and the shift sleeve 52 move in the preferred direction and the shift sleeve 52 can be held in the preferred gear position (first gear). This ensures that the drive connection to the harvesting deck 16 remains established and that the user does not have to interrupt his harvesting work or can continue his harvesting work even in the event of a hydraulic system failure.

[0037] In the above embodiment, the first gear position (in which the shift sleeve 52 is engaged with the planetary gear set 42) is the gear position in the preferred direction or the gear position for the normal operating mode of the agricultural machine 10. The second gear position (in which the shift sleeve 52 is engaged with the second drive element 92) forms the reverse operating mode.

[0038] Thus, in the first gear, the drive flow proceeds from the first drive element 22 via the sun gear 40 and via the planetary gear 44 rolling in the ring gear 46 to the planetary carrier 48, and from there via the shift sleeve 52 to the gear 90 of the output shaft 88. In the second gear, the drive flow proceeds from the second drive element 92 via the shift sleeve 52 to the gear 90 of the output shaft 88. In the first gear, the direction of rotation of the drive shaft 88 is opposite to the direction of rotation of the drive shaft 88 in the second gear, in which the transmission is driven in reverse mode if, for example, the harvesting deck and / or the crop conveying device in the conveyor channel of the combine harvester are blocked or obstructed.

[0039] The shifting device 50 is shifted by applying hydraulic pressure to the pressure chambers 64, 66 and relieving pressure, wherein, when the second pressure chamber 66 is relieved of pressure and / or when the first pressure chamber 64 is simultaneously pressurized, the adjusting rod 58 and thus the shift fork 54 and the shift sleeve 52 are moved into the first gear position for the normal operating mode, in which the shift sleeve 52 is in drive connection with the planetary gear set 42 (see Figure 5When pressure is applied to the second pressure chamber 66 and / or pressure is possibly released from the first pressure chamber 64, the adjusting rod 58, and therefore the shift fork 54 and the shift sleeve 52, moves toward the second gear for the reverse operating mode. In this second gear, the shift sleeve 52 is driven and connected to the second drive element 92. The application of pressure to the first pressure chamber 64 can be low or, depending on the design of the spring elements 70 and 72, can be omitted entirely, since the spring elements 70 and 72 already push the adjusting rod 58 toward the first gear. However, the spring elements 70 and 72 are preferably designed so that, in normal operating mode, a hydraulic system failure only prevents the shift sleeve 52 from automatically shifting out of the first gear. However, pressure is applied to the first pressure chamber 64 to shift from the second gear to the first gear. This ensures a certain shifting dynamic. However, to shift into the second gear, the application of pressure to the second pressure chamber 66 must be high, since the adjusting rod 58 must move against the actuating force of the spring elements 70 and 72.

Claims

1. A shifting device (50) for a transmission (24), the transmission having a first transmission housing part and a second transmission housing part (28, 30), wherein the shifting device (50) comprises: A shift sleeve (52), a shift fork (54) engaged in the shift sleeve (52), an adjusting actuator (56) arranged in the first transmission mechanism housing part (28), and an adjusting rod (58) connected to the adjusting actuator (56) at one end and connected to the shift fork (54) at the other end, wherein the adjusting rod (58) is supported in a first guide hole (60) formed in the first transmission mechanism housing part (28), characterized in that a second guide hole (62) formed parallel to the first guide hole (60) is formed in the first transmission mechanism housing part (28) and a guide rod (63) oriented parallel to the adjusting rod (58) is provided, one end of the guide rod is connected to the shift fork (54) and the other end is supported in the second guide hole (62).

2. The shifting device (50) according to claim 1, characterized in that The first guide hole (60) is formed between the adjustment actuator (56) and the shift fork (54).

3. The shifting device (50) according to claim 1, characterized in that At least one spring element (70, 72) is arranged, which urges the shift fork (54) toward a gear position in a preferred direction.

4. The shifting device (50) according to claim 3, characterized in that The spring element (70, 72) is arranged between the first transmission housing part (28) and the shift fork (54).

5. The shifting device (50) according to claim 3 or 4, characterized in that: The spring element (70, 72) is formed as a compression spring and extends at least partially into spring guide holes (74, 76) formed in the first transmission housing part (28) parallel to the first guide hole (60) and the second guide hole (62).

6. The shifting device (50) according to claim 3 or 4, characterized in that: The spring element (70, 72) includes a first spring element and a second spring element.

7. A transmission (24) comprising a shifting device (50) according to claim 1.

8. The transmission (24) according to claim 7, comprising: a first transmission housing part (28) and a second transmission housing part (30) connected to the first transmission housing part (28), an output shaft (88) extending through the first transmission housing part (28) and the second transmission housing part (30), a first drive element (22) that can be connected to the output shaft (88) in terms of driving via a planetary gear set (42), a second drive element (92) that can be connected to the output shaft (88) in terms of driving, and a gear (90) that is connected to the output shaft (88) in a rotationally fixed manner and engages with the shift sleeve (52), wherein in a first gear position, the shift sleeve (52) can engage with the planetary gear set (42) and the gear (90); and in a second gear position, the shift sleeve (52) can engage with the second drive element (92) and the gear (90).

9. The transmission mechanism (24) according to claim 8, characterized in that At least one spring element (70, 72) is arranged, which pushes the shift fork (54) toward a gear position in a preferred direction, the first gear position being a gear position in the preferred direction.

10. The transmission mechanism (24) according to claim 8 or 9, wherein the planetary gear set (42) comprises: A ring gear (46) arranged on the second transmission housing part (30), a planetary set (44) rolling in the ring gear (46), a planetary carrier (48) capable of engaging with the shift sleeve (52) in the first gear, and a sun gear (40) connected to the first drive element (22) and rolling with the planetary set (44).

11. The transmission mechanism (24) according to claim 8 or 9, wherein the first drive element (22) comprises a belt drive drum.

12. The transmission (24) according to claim 8 or 9, wherein the second drive element (92) comprises a worm gear driven by a transmission worm (94).

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