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Title:
MECHANISM FOR BALANCING A BOGIE
Document Type and Number:
WIPO Patent Application WO/2012/123630
Kind Code:
A1
Abstract:
The invention relates to a mechanism for balancing a bogie, particularly a bogie where the bogie comprises a bogie frame (3) fixed in a swivelled manner by a fixing joint (2) to the chassis (1) of a vehicle, the wheels of the bogie being mounted on bearings on the bogie frame (3) and rotated by means of actuators (5a, 5b) on the bogie frame (3). In the mechanism for balancing a bogie according to the invention, the actuator (5a, 5b) is a motor whose frame (6a, 6b) is mounted on bearings on the bogie frame (3) to be rotatable with respect to its drive shaft, and moment transfer means (12) are provided between the frame (6a, 6b) of the actuator (5a, 5b) and the chassis (1) of the vehicle, for connecting the frame (6a) of the actuator (5a) to the chassis (1) of the vehicle, wherein the twisting moment (Mvri) caused by rotation of the wheel on the frame (6a) of the actuator (5a) is transferred from the frame (6a) of the actuator (5a) by the moment transfer means (12) to the chassis (1) of the vehicle. Alternatively, the actuator in the mechanism for balancing a bogie according to the invention may be a hub motor whose mounting shaft is mounted on bearings on the bogie frame (3), the moment transfer means (12) being connected between the mounting shaft of the actuator and the chassis (1) of the vehicle in the above-mentioned way, and the frame of the actuator being connected to the wheel of the vehicle.

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Inventors:
HANKAMÄKI, Olli (Pulkkisentie 4, Valkkinen, 37420, FI)
Application Number:
FI2012/050195
Publication Date:
September 20, 2012
Filing Date:
February 27, 2012
Export Citation:
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Assignee:
JOHN DEERE FORESTRY OY (Lokomonkatu 21, Tampere, FI-33100, FI)
HANKAMÄKI, Olli (Pulkkisentie 4, Valkkinen, 37420, FI)
International Classes:
B60G5/02
Foreign References:
FR2086585A5
US20100012401A1
Attorney, Agent or Firm:
TAMPEREEN PATENTTITOIMISTO OY (Hermiankatu 1 B, Tampere, FI-33720, FI)
Download PDF:
Claims:
Claims:

1. A bogie balancing mechanism, particularly for a bogie in which the bogie comprises a bogie frame (3) mounted in a swivelled manner by a mounting joint (2) to the chassis (1 ) of a vehicle, the wheels of the bogie being mounted on bearings on the bogie frame (3) and rotated by means of actuators (5a, 5b) on the bogie frame (3), characterized in that the actuator (5a, 5b) is a motor whose frame (6a, 6b) is mounted on bearings on the bogie frame (3) to be rotatable with respect to its drive shaft, and that moment transfer means (12) are provided between the frame (6a, 6b) of the actuator (5a, 5b) and the chassis (1 ) of the vehicle, for connecting the frame (6a) of the actuator (5a) to the chassis (1 ) of the vehicle, wherein the twisting moment (Mvri) caused by rotation of the wheel on the frame (6a) of the actuator (5a) is transferred from the frame (6a) of the actuator (6a) by the moment transfer means (12) to the chassis (1 ) of the vehicle.

2. The bogie balancing mechanism according to claim 1 , characterized in that the moment transfer means (12) are provided between the frame (6a) of at least one actuator (5a) in the bogie frame (3) and the bogie mounting shaft (10) connected to the mounting joint (2) of the bogie frame (3) and mounted on the chassis (1 ) of the vehicle.

3. The bogie balancing mechanism according to claim 2, characterized in that the bogie frame (3) comprises two wheels, each comprising an actuator (5a, 5b), and that the moment transfer means (12) are provided between the frame (6a, 6b) of each actuator (5a, 5b) and the bogie mounting shaft (10).

4. The bogie balancing mechanism according to any of the claims 1 to 3, characterized in that the moment transfer means (12) comprise a power transmission shaft (13), a torsion shaft (15) and a balancing shaft (17), which are connected to each other in a swivelled manner, and that the torsion shaft (15) is provided between the frame (6a) of the actuator (5a) and the power transmission shaft (13), and the balancing shaft (17) is provided between the power transmission shaft (13) and the bogie mounting shaft (10) mounted on the chassis (1 ) of the vehicle.

5. The bogie balancing mechanism according to claim 4, characterized in that the torsion shaft (15) is mounted on the frame (6a) of the actuator (5a), and the balancing shaft (17) is mounted on the bogie mounting shaft (10), and that the torsion shaft (15) and the balancing shaft (17) are tilted primarily at equal angles towards each other, the bogie frame (3) and the chassis (1 ) of the vehicle being parallel.

6. The bogie balancing mechanism according to claim 4 or 5, characterized in that the torsion shaft (15) and the balancing shaft (17) are at an angle of about 10° towards each other, the bogie frame (3) and the chassis (1 ) of the vehicle being horizontal and parallel.

7. The bogie balancing mechanism according to any of the claims 4 to 6, characterized in that the length of the torsion shaft (L2) formed by the bal- ancing shaft (17) is adjustable.

8. The bogie balancing mechanism according to claim 7, characterized in that the adjustment is implemented by making the position or length of the balancing shaft (17), or the place of the mounting point (14b) between the power transmission shaft and the balancing shaft adjustable.

9. The bogie balancing mechanism according to any of the claims 4 to 8, characterized in that the length of the torsion shaft (L-i) formed by the torsion shaft (15) is adjustable.

10. The bogie balancing mechanism according to claim 9, characterized in that the adjustment is implemented by making the position or length of the torsion shaft (15), or the place of the mounting point (14a) between the power transmission shaft (13) and the torsion shaft (15) adjustable.

1 1 . A bogie balancing mechanism, particularly for a bogie in which the bogie comprises a bogie frame (3) mounted in a swivelled manner by a mounting joint (2) to the chassis (1 ) of a vehicle, the wheels of the bogie being mounted on bearings on the bogie frame (3) and rotated by means of actua- tors (5a, 5b) on the bogie frame (3), characterized in that the actuator (5a, 5b) is a hub motor whose mounting shaft is mounted on bearings on the bogie frame (3) to be rotatable with respect to it, and that moment transfer means (12) are provided between the mounting shaft of the hub motor and the chassis (1 ) of the vehicle, for connecting the mounting shaft of the actuator to the chassis (1 ) of the vehicle, wherein the twisting moment (Mwi) caused on the mounting shaft of the actuator by rotation of the wheel is transferred from the mounting shaft of the actuator by the moment transfer means (12) to the chassis (1 ) of the vehicle.

12. The bogie balancing mechanism according to claim 1 1 , characterized in that the moment transfer means (12) comprise a torsion shaft (15), a power transmission shaft (13) and a balancing shaft (17), which are connected to each other in a swivelled manner, and that the torsion shaft (15) is provided between the mounting shaft of the actuator and the power transmission shaft (13), and the balancing shaft (17) is provided between the power transmission shaft (13) and the mounting shaft (10) mounted on the chassis (1 ) of the vehicle.

Description:
MECHANISM FOR BALANCING A BOGIE Field of the invention The invention relates to a mechanism for balancing a bogie, particularly a bogie comprising a bogie frame fixed in a swivelled manner by a fixing joint to the chassis of a vehicle, the wheels of the bogie being mounted on bearings on the bogie frame and rotated by means of actuators in the bogie frame. Background of the invention

Particularly forest machines but also many other working machines which are used for moving primarily on uneven terrain, are often equipped with driving gears to improve their off-road performance and to stabilize their steering. The driving gears are mounted on the chassis of the vehicle, on bogies fastened to be turnable in relation to the cross shaft. Such bogies, having drive wheels (normally two or more in succession) installed on their bogie frames, are normally equipped with a balancing mechanism for preventing the harmful effects of the twisting moment caused by the drive of the wheels on the bogie frame. In an unbalanced bogie frame, said twisting moment tends to lift up (i.e. to disengage) the front wheels of the bogie frame and to press the rear wheels of the bogie frame onto the ground more strongly. This, in turn, causes that the weight of that part of the working machine which falls on the wheels of said bogie is not evenly distributed between the wheels of this bogie; as a result, the friction force (holding) between the bogie wheels and the surface of the ground becomes unequal for the different wheels. The unequal distribution of the friction force leads to the fact that the transmission device of that wheel/those wheels of the bogie frame, on which the greater part of the weight falls, is subjected to a greater load than the transmission device on that side, on which the wheel/wheels tend to be disengaged. Naturally, in extreme cases, this may result in overloading and damage of the transmission device of those wheels, on which the greater part of the loads falls. To solve this problem, many such transmission solutions are currently used for example in forest machines, in which the rotating movement and the twisting moment generated by a motor placed in the frame of the forest machine is transmitted to the wheels of the bogie frame by means of a moment distributor formed by a planetary gear and a gear transmission device or a chain transmission in connection with the bogie frame. The moment distributor formed by a planetary gear compensates for the lifting effect caused by the twisting moment of the wheels, wherein the weight of the forest machine and thereby the twisting moment falling on the wheels is distributed more evenly between the wheels in the same bogie.

At present, drive wheels mounted on a bogie are also driven by hydraulic or electric motors installed on bogie shafts, the hub of the wheel being mounted on the motor shaft, or the motors being so-called hub motors whose shaft is mounted on the bogie frame, and the wheel being in connection with the rotary motor frame. Thus, it is naturally not possible to use solutions of the above described kind, based on a planetary gear, because the rotary movement is not transmitted to the drive wheels mechanically through the mounting joint of the bogie frame. In these situations, it has therefore been neces- sary to apply balancing mechanisms driven by separate actuators. In a typical bogie balancing mechanism of this kind, driven by a separate actuator, the balancing of the bogie is implemented by hydraulic cylinders installed between the frame of the working machine and the bogie frame. In solutions of this type, the counterforce caused by the hydraulic cylinder is adjusted, for example, on the basis of the pressure of pressurized medium supplied to hydraulic motors driving the wheels, in such a way that the supporting force between the wheels on the bogie and the surface of the ground remains as even as possible. In the above described way, it is possible to even out the pressure distribution between the wheels of the bogie. In the version equipped with a separate actuator, the pressure distribution can also be adjusted in a way different from this basic aim, if this is desired, for example, because of the terrain conditions. However, the separate systems make the bogie structure complex and, among other things, increase the weight as well as the manufacturing and operating costs of the working machine.

Brief summary of the invention It is the aim of the invention to achieve a novel type of balancing mechanism for a bogie, to eliminate the above mentioned disadvantages involved with current bogie balancing systems, relating to bogies in which the actuators for rotating the wheels are placed on the bogie frame. In particular, the aim of the invention is to introduce a bogie balancing mechanism which can be used in combination with a bogie where the wheel driving mechanism can be a conventional motor or a so-called hub motor at the wheel mounting point, but which does not require separate balancing devices driven by actuators in the working machine or the bogie.

The inventive idea of the bogie balancing mechanism according to the invention is to utilize the counter-moment effected by the rotation of the wheels of the bogie on the actuators of the wheels, for balancing the bogie frame in such a way that this counter-moment is transmitted by a mechanical transmission shaft from the motor that rotates the wheel to the chassis of the vehicle. By changing the lengths of the moment shafts, the bogie can be balanced in a desired way either to distribute the weight between the wheels of the bogie as evenly as possible, or alternatively by over- or underbalancing it in such a way that the balancing moment is either greater or smaller than the twisting moment caused by the bogie wheels on the bogie frame. To put it more precisely, the bogie balancing device according to the invention is characterized i what will be presented in the characterizing parts of inde- pendent claims 1 and 11. Furthermore, the dependent claims will present some preferred embodiments of the balancing mechanism according to the invention.

Thanks to the bogie balancing mechanism according to the invention, it is possible in bogies based on a bogie frame mounted in a swivelling manner on the chassis of the vehicle, to use, as actuators for the wheels, a motor at the wheel, for example an electric or hydraulic motor, without needing to provide the bogie frame with a balancing mechanism operated by separate actuators. Thanks to this, the bogie structure is simpler and the bogie has a lower weight. Furthermore, thanks to the omission of separate actuators, the bogie equipped with a bogie balancing mechanism according to the invention is less expensive in its manufacturing and operating costs than a bogie equipped with a bogie balancing mechanism based on balancing by separate actuators. Furthermore, the bogie balancing mechanism according to the invention makes it possible to adjust the balancing by a simple mechanical control mechanism. Description of the drawings

In the following, the invention will be described in more detail with reference to the appended drawings, in which

Fig. 1 shows a bogie equipped with a bogie balancing mechanism according to the invention, seen in a slanted view from above;

Fig. 2 shows the hub, the actuator, the bogie mounting shaft, and the moment transfer means of the bogie balancing mechanism according to Fig. 1 , seen in a slanted view from above, without other parts of the bogie, in the position in which they are when the chassis of the vehicle and the bogie are in the position shown in Fig. 1 ;

Fig. 3 shows the bogie of Figs. 1 and 2 in a side view; shows the bogie of the preceding figures in a side view so that the bogie frame and the left wheel hub of the bogie are shown by broken lines in the figure; shows the bogie of the preceding figures in a side view where the bogie is in a sharp rise to the left so that the bogie frame and the left wheel hub of the bogie are shown by broken lines in the figure; and shows the bogie of the preceding figures in a side view where the bogie is in a sharp rise to the right so that the bogie frame and the left wheel hub of the bogie are shown by broken lines in the figure.

Detailed description of the invention

Figure 1 shows a bogie formed of a bogie frame 3 mounted with a mounting joint 2 on the chassis 1 of a vehicle. In this embodiment, both ends of the bogie frame are provided with a drive wheel (Figs. 1 to 6 do not show the wheels in whole but only the hubs 4a and 4b). The drive of the drive wheels of the bogie frame 3 is implemented by wheel-specific actuators 5a and 5b which are e.g. electric or hydraulic motors comprising a frame and a drive shaft rotating with respect to the frame. The actuator 5a is mounted on a bearing 8 on a housing 7a at this end in such a way that the frame 6a of the actuator 5a can rotate freely around its central axis (drive shaft) inside the housing 7a. Consequently, in this embodiment, the balancing mechanism is only provided for the left wheel, while the right-hand-side actuator 5b of the bogie frame is fixed in a housing 7b. Inside the hubs 4a and 4b, for example a planetary gear can be provided, by which the rotary movement generated by the actuators 5a and 5b is transmitted to the wheel of the vehicle.

Figure 2 shows that the bogie frame 3 is, in this case, completely hollow, for example a shell configuration with plate structure, mounted at its centre on a bearing 11 to a mounting shaft 10 which is fixed by means of a fixing flange 9 fastened by screws to the chassis 1 of the vehicle and extends laterally from it. Consequently, the mounting shaft 10 and the housing (not shown in the figures) for the bearing 11 in the bogie frame form in this case the mounting joint 2 of the bogie frame. Figure 2 also shows moment transfer means 12 mounted between the left actuator 5a and the mounting shaft 10. The moment transfer means 12 consist, in this embodiment, of a torsion shaft 15, a power transmission shaft 13 and a balancing shaft 17 in such a way that the power transmission shaft 13 is fixed at its first end 14a in a swivelling manner to the torsion shaft 15 fixed to the rear part of the frame 6a of the actuator 5a, and at its second end 14b to the balancing shaft 17 fixed to the mounting shaft 10. Thus, the bogie balancing mechanism can be considered to consist, in the embodiment of Figs. 1 to 6, of the frame 6a of the actuator 5a mounted on bearings on the bogie frame 3, the moment transfer means 12, and the mounting shaft 10 mounted on the chassis 1 of the vehicle. The bearing of the frame 6a of the actuator 5a in the housing 7a is implemented, for example, by groove ball bearings or roller bearings installed in recesses provided for this purpose in the housing 7a in such a way that the frame 6a of the actuator 5a cannot move or turn inside the housing in its depth direction or cross direction.

The torsion shaft 15 is a part shaped as shown in the figures and connected to the frame 6a of the actuator 5a by, for example, screwing. It can also be fastened to the frame 6a of the actuator 5a in a stationary manner, for example by welding, if the frame 6a and the torsion shaft 15 are made of a weld- able material. The length of the torsion shaft 15 is such that the distance between the fixing point of the first end 14a of the power transmission shaft 13 and the centre of the drive shaft of the actuator 5a is equal to the distance between the second end 14b of the power transmission shaft 13 and the centre of the mounting shaft 10. In this case, the end of the torsion shaft 14a is provided, as shown in Fig. 1 , with two lugs adjacent to and spaced from each other, between which lugs the first end 14a of the power transmission shaft 13 is fixed by means of a mounting pin to be fitted through holes in the lugs and a hole at the first end 14a of the power transmission shaft 13. For locking the mounting pin in the holes, the lugs and the pin may be provided with, for example, a threading, a locking ring, or another suitable locking means.

As shown in Figs. 1 to 6, the power transmission shaft 13 is, for example, a rod-like piece cast of metal, its first end 14a and second end 14b being expanded in the way shown in the figures so as to provide them with mounting holes for mounting the power transmission shaft 13 between the ends of the torsion shaft 15 and the balancing shaft 17 in the way shown in the figures. The length of the power transmission shaft 13 is slightly shorter than the distance between the mounting shaft 10 and the drive shaft of the actuator 5a, to enable the mounting of the torsion shaft 15 and the balancing shaft 17 in a position inclined towards each other, as shown in the figures.

The balancing shaft 17 is a rod whose first end is provided with an opening, through which the mounting shaft 10 has been fitted through the first end of the balancing shaft 17. The mounting shaft 10 and the opening at the first end of the balancing shaft 143 are provided with complementary wedge grooves, between which a taper pin is installed to prevent the rotation of the balancing shaft with respect to the mounting shaft (the wedge grooves and the taper pin are not shown in the figures). The second end of the balancing shaft 17 is provided with fastening lugs and holes similar to the fastening at the second end of the torsion shaft 15, between which lugs and holes the second end 14b of the power transmission shaft 13 is mounted in a swivelling manner in the same way as the first end 14a. Due to the structure of the above described moment transfer means 12, the (balancing) forces F caused by the torsion shaft 15 on the power transmission shaft 13 are transferred from the power transmission shaft 13 via the fastening of this second end 14a to the balancing shaft 17 which, in turn, results in a twisting moment Μ ν κι on the mounting shaft, tending to rotate the chassis 1 of the vehicle with respect to the centre of the mounting shaft. Because of this opposite supporting force F t -i = -F r1 on the bogie frame 3 caused by the balancing shaft 15 on the power transmission shaft 13, the supporting moment M M = -M V M tends to rotate the bogie frame 3 in a direction opposite to the twisting moment Myf = Μνη+Μ^ caused by the drive of its wheels (that is, to balance the bogie). Thus, the magnitude of the balancing moment M V M is determined not only by the magnitude of the force effective on the balancing shaft 17 but also by the perpendicular distance between the force and the centre of the mounting shaft 10, that is, in practice, the position of the power transmission shaft 13 with respect to the balancing shaft 17.

In Figs. 3 and 4, the bogie frame 3 is shown in the horizontal position and parallel to the chassis 1 of the vehicle. Thus, the torsion shaft 15 mounted on the frame 6a of the actuator 5a, and the balancing shaft 17 mounted on the mounting shaft 10, are at an angle of about 10° to the horizontal direction towards each other, as shown in Fig. 4. In this situation, the vertical distance between the mounting point of the first end 14a (that is, the end on the side of the actuator 5a) of the power transmission shaft 13 and the rotation shaft of the actuator 5a is equal to the vertical distance between the mounting point of the second end 14b (that is, the end on the side of the mounting joint 1 1 ) and the centre of the mounting shaft. These transverse distances between the centre of the central shaft parallel to the longitudinal direction of the power transmission shaft 13 and the drive shaft of the actuator 5a and the centre of the bogie mounting shaft 10 determine the magnitude of the balancing moment effective on the bogie frame 3 via the mounting shaft 10, which magnitude is thus dependent on the ratio between the lengths of these torsion shafts. Consequently, in this situation, the twisting moment M vr i caused on the frame 6a of the actuator 5a by rotating the hub 4a and the wheel on it causes a twisting moment M vk1 on the mounting shaft 10 mounted on the chassis 1 of the vehicle and thereby a supporting twisting moment Mvt-i on the bogie frame, said moment thus being equal in an absolute value to the twisting moment M vr caused on the frame 6a of the actuator 5a by rotating the hub 4a, but having an opposite sign. In other words, in this situation, the power transmission means 12 balance the bogie frame 3 with a twisting moment that has exactly the same absolute value than the moment effective on the frame 6a of the actuator 5a for the left wheel of the bogie; that is, M v n

In the situation of Fig. 5, that is, when the bogie frame 3 is in a position tilted upwards to the left and the chassis 1 of the vehicle is still in the horizontal position, the balancing moment Mv t i transmitted by the moment transfer means 12 of the actuator 5a to the mounting shaft 10 is at its lowest (that is, Mvn < V K I ), and in the position of Fig. 6, this bogie balancing moment M vr) is at its highest (that is, M vr > Iv -i). This is because due to said positions, in the case of Fig. 5, the transverse distance l_i between the first end 14a of the power transmission shaft 13 (with respect to the direction of the central shaft 13' of the power transmission shaft 13) and the centre of the drive shaft of the actuator 5a is greater than the transverse distance L 2 between the second end 14b and the centre of the mounting shaft 10; in other words, the force F r i caused by the twisting moment M vr i of the frame 6a of the actuator 5a and transmitted via the power transmission shaft 13 to the balancing shaft 17 produces a smaller twisting moment M V on the mounting shaft 10 than the twisting moment M vM caused on the frame 6a of the actuator 4b by the rotation of the wheel. Instead, in the case of Fig. 6, in which the frame 3 of the bogie is tilted upwards to the right, the situation is completely opposite. The transverse distance between the first end 14a of the power transmission shaft 13 and the centre of the driving shaft of the actuator 5a is smaller than the transverse distance L 2 between the second end 14b and the centre of the mounting shaft 10, in which case the force F r caused by the twisting moment of the frame 6a of the actuator 4a and transmitted via the power transmission shaft 13 to the balancing shaft 17 produces a greater twisting moment ν κι on the mounting shaft 10 than the twisting moment M vr caused on the frame 6a of the actuator 5a by the rotation of the wheel.

In the bogie according to Figs. 1 to 6, the mounting joint 2 of the bogie frame and the hubs 4a and 4b of the wheels are at the same height level in the vertical direction. Therefore, the twisting moment caused on the bogie frame by the driving of the hub 4a and the wheel, with respect to the centre of the mounting shaft 10, is equal in its absolute value to the twisting moment M k1 transferred by the balancing mechanism via the torsion shaft 15, the power transmission shaft 13 and the balancing shaft 17 to the centre of the mounting shaft 10, and the resulting supporting moment Mvti to balance the bogie frame (the direction of the moment thus being opposite to the twisting moment M vk i caused by the force F r -i). Consequently, if no twisting moment were caused by the drive F 2 of the hub 4b and the respective wheel, that is, if F 2 = 0 and thereby Mvf2 = 0, then the balancing mechanism in the bogie shown in Figs. 1 to 6 would balance the bogie frame 3 completely in the situation where the bogie frame 3 is parallel to the chassis 1 of the vehicle. If the bogie frame 3 is in the position shown in Fig. 5, it would be under- balanced, and in the position shown in Fig. 6, it would be overbalanced, if F 2 = 0 and Mvt2 = 0 (in other words, the hub 4b would not be driven). Now, in reality, however (because also the hub 4b is driven), only the balancing mechanism in the left wheel shown in Figs. 1 to 6 underbalances the bogie as long as < + Iv Assuming that Ft = F 2 , in other words that the weight caused by the chassis 1 of the vehicle on the bogie were evenly distributed between both wheels of the bogie, the bogie of Figs. 1 to 6 would be completely balanced when the bogie frame would be tilted so much upwards to the right (the chassis of the vehicle being in the horizontal position) that the transverse distance Li between the fastening point of the first end 14a of the power transmission shaft 13 and the centre of the drive shaft of the actuator 5a were half the transverse distance L 2 between the fastening point of the second end 14b of the power transmission shaft 13 and the centre of the mounting shaft 10. Furthermore, it should be noted that in reality, the ground surface shape will affect the directions of the forces F-i and F 2 . It has been assumed above that the ground surface is flat and parallel to a straight line drawn between the centres of the hubs 4a and 4b of the bogie frame 3. Furthermore, it should be taken into account that if the transmission ratio of the hub 4a is≠ 1 , it will also affect the function of the bogie balancing mechanism, because the twisting moment of the motor needed for producing the twisting moment Mvn effective on the wheel will then be ≠Μνπ . In other words, if the transmission ratio of the planetary gear between the actuator 5a and the hub 4a is >1 , the balancing effect diminishes, and if the transmission ratio is <1 , the balancing effect increases. The bogie balancing mechanism according to the invention may naturally also comprise a solution which deviates slightly from the solution of Figs. 1 to 6 and in which a balancing mechanism of the above described type is provided between both the actuators 5a and 5b of the drive wheels of the bogie and the mounting shaft 10. Consequently, the actuator 5b is also mounted in the housing 7b by means of a bearing similar to the bearing 8, wherein the frame 6b of the actuator can rotate freely with respect to the housing 7b, in case no torsion shaft, power transmission shaft or balancing shaft of the balancing mechanism (or mounting on the balancing shaft 17) is installed. When also the second wheel of the bogie frame is equipped with a balancing mechanism, that is, said shafts, this will influence the function of the balancing in such a way that in the position of Figs. 3 and 4, the bogie frame is balanced completely (provided that the wheels of the bogie frame are on a flat ground and the transmission ratio between the hubs 4a and 4b = 1 ).

In the positions of Figs. 5 and 6, the balancing of the bogie of Figs. 1 to 6, where both wheels are balanced, still remains complete, if the ground surface is parallel to the bogie frame 3, because e.g. in the case of Fig. 5, the balancing moment produced by the actuator 5b of the right wheel (not shown in the figures) increases as much as the balancing moment Mvti produced by the left actuator diminishes due to the tilting of the bogie frame. In the case of Fig. 6, the function is similar but here the balancing moment produced by the actuator 5b of the right wheel diminishes and the balancing moment Mvti produced by the actuator 5a of the left wheel increases.

In the application according to Figs. 1 to 6, the actuators 5a and 5b are, for example, conventional electric or hydraulic motors. Instead of them, it is also possible to use so-called hub motors in which the torsion shaft 15 is connected to the motor shaft and the motor frame forms the hub or part of it. Alternatively, the bogie frame can also be implemented in such a way that it is not a box-like structure but, for example, a profile beam structure or a sheet structure. Thus, the torsion shaft, the power transmission shaft and the balancing shaft of the balancing mechanism can be partly or entirely visible, while they are completely inside the bogie structure in the solution shown in Figs. 1 to 6. In an embodiment of the balancing mechanism according to the invention, the position and/or length of the balancing shaft can be adjustable. Alternatively or in addition, the position and/or length of the torsion shaft can also be adjustable. With these adjustments, it is possible to change the lengths of the torsion shafts formed by the torsion shaft and the balancing shaft, that is, the transverse distance between the centre of the mounting shaft of the bogie and the straight line parallel to the power transmission shaft (or its extension), and/or the transverse distance between the centre of the drive shaft of the actuator and the straight line parallel to the central axis of the power transmission shaft (or its extension). In practice, such adjustments can be applied to adjust the strength of the balancing and/or the bogie frame positions in which the balancing is the strongest and the weakest. Alternatively, the moment transfer means of the bogie balancing mechanism can consist of, for example, a gear or chain transmission between the actuator frame in the bogie frame and the chassis of the vehicle, by which transmission the twisting moment caused on the frame of the actuator by the rotation of the wheel is transferred to the chassis of the vehicle in a way cor- responding to that described above. Furthermore, the balancing mechanism according to the invention may also, in many other respects, differ from the above described example embodiments; in other words, it is not limited to the above described example embodiments but may vary within the scope of the inventive idea formed by the claims below.