BOGIE FOR A FORESTRY VEHICLE AND VEHICLE WITH AT LEAST ONE BOGIE AXLE

Abstract

A bogie for a forestry vehicle is disclosed that includes a bogie body, which has a first wheel hub for arrangement of a first wheel and a second wheel hub for arrangement of a second wheel. The bogie includes a swing arm pivotably hinged at a first end portion on the bogie body, and at a second end portion has a wheel hub for arrangement of a center wheel between the first wheel and the second wheel. The bogie further includes a spring and/or damper element, which at one end portion is hinged on the bogie body and at the other end portion is hinged on the second end portion of the swing arm and by means of which the swing arm is capable of being applied with force. A vehicle, in particular a forestry vehicle, is also disclosed having at least one bogie axle with such a bogie.

Claims

1. A bogie for a forestry vehicle, comprising: a bogie body, which has a first wheel hub for arrangement of a first wheel and a second wheel hub for arrangement of a second wheel, a swing arm, which is pivotably hinged at a first end portion on the bogie body and at a second end portion comprises a wheel hub for arrangement of a center wheel between the first wheel and the second wheel, and a spring and/or damper element, which at one end portion is hinged on the bogie body and at the other end portion is hinged on the swing arm and by means of which the swing arm is capable of being applied with force.

2. The bogie according to claim 1, wherein the first end portion of the swing arm is mounted on the bogie body by means of a rotary joint, which preferably comprises at least two slide bearing bushings.

3. The bogie according to claim 1, wherein the swing arm and the spring and/or damper element relative to a linkage of the bogie body for hinging the bogie on an axle beam of a bogie axle are mounted on the same side or on opposite sides on the bogie body and/or that the swing arm and the spring and/or damper element are hinged on the same component of the bogie body or on different components of the bogie body.

4. The bogie according to claim 1, wherein the spring and/or damper element at least in portions is arranged within an associated casing of the swing arm.

5. The bogie according to claim 1, wherein a stop is provided, by means of which a movability of the swing arm relative to the bogie body is limited.

6. The bogie according to claim 1, wherein at least one rotation axis of the swing arm and at least one rotation axis of the spring and/or damper element are arranged axially parallel relative to each other and/or that at least one rotation axis of the swing arm is arranged coaxially relative to a rotation axis of the first or second wheel hub.

7. The bogie according to claim 1, wherein the spring and/or damper element comprises a hydraulic cylinder.

8. The bogie according to claim 7, wherein the hydraulic cylinder is associated with a control system, which is configured to control and/or regulate a pressurization of the hydraulic cylinder by means of a hydraulic liquid.

9. The bogie according to claim 8, wherein the control system is configured to apply the hydraulic cylinder at least within a predetermined pivoting range of the swing arm with a predetermined, in particular constant pressure and/or to limit a pressure in the hydraulic cylinder to a predetermined pressure value.

10. The bogie according to claim 1, wherein a lever arm between the spring and/or damper element and a pivoting joint of the swing arm decreases upon pivoting the swing arm in a direction away from the ground and/or that a downward force on the center wheel decreases upon pivoting the swing arm in a direction away from the ground, if a constant force is applied on the spring and/or damper element.

11. The bogie according to claim 1, wherein the wheel hub for arrangement of the center wheel can be pivoted between a bearing position, in which a center of the wheel hub is positioned below a line connecting a center of the first wheel hub and a center of the second wheel hub, and a rest position, in which a center of the wheel hub is positioned above the line connecting the center of the first wheel hub and the center of the second wheel hub.

12. A vehicle in particular forestry vehicle, comprising: at least one bogie axle that comprises a bogie according to claim 1.

13. The vehicle according to claim 12, wherein the first wheel is arranged on the first wheel hub of the bogie body, the second wheel is arranged on the second wheel hub of the bogie body, and the center wheel is arranged on the wheel hub of the swing arm.

14. The vehicle according to claim 13, wherein at least one out of the group of the first wheel, second wheel, and center wheel is a rubber air wheel.

15. The vehicle according to claim 13, wherein the center wheel has a smaller dimension than the first wheel and/or the second wheel.

16. The vehicle according to claim 12, wherein the swing arm preferably by means of the spring and/or damper element is capable of being pivoted between a bearing position, in which the center wheel is in contact with a ground on which the vehicle is positioned, and a rest position, in which the center wheel is lifted off the ground.

Description

[0022] Further features of the invention are apparent from the claims, the figures and the description of figures. The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of figures and/or shown in the figures alone are usable not only in the respectively specified combination, but also in other combinations without departing from the scope of the invention. Thus, implementations are also to be considered as encompassed and disclosed by the invention, which are not explicitly shown in the figures and explained, but arise from and can be generated by separated feature combinations from the explained implementations. Implementations and feature combinations are also to be considered as disclosed, which thus do not have all of the features of an originally formulated independent claim. Moreover, implementations and feature combinations are to be considered as disclosed, in particular by the implementations set out above, which extend beyond or deviate from the feature combinations set out in the relations of the claims. The figures show in:

[0023] FIG. 1 a schematic side view of a bogie according to a first embodiment, wherein a swing arm is pivoted to a bearing position;

[0024] FIG. 2 a schematic side view of the bogie according to the first embodiment, wherein the swing arm is pivoted to a rest position;

[0025] FIG. 3 a schematic side view of the bogie according to a second embodiment, wherein the swing arm is pivoted to the bearing position;

[0026] FIG. 4 a schematic side view of the bogie according to the second embodiment, wherein the swing arm is pivoted to the rest position;

[0027] FIG. 5 a schematic side view of the bogie according to a third embodiment, wherein the swing arm is pivoted to the bearing position; and

[0028] FIG. 6 a schematic side view of the bogie according to a fourth embodiment, wherein the swing arm is pivoted to the bearing position.

[0029] FIG. 1 shows a schematic side view of a bogie 10 for a bogie axle (not shown) for a forestry vehicle according to a first embodiment. The bogie 10 has a bogie body 12, which has a first wheel hub 14a for arrangement of a first wheel 16a and a second wheel hub 14b for arrangement of a second wheel 16b. The wheel hubs 14a, 14b of the present embodiment are arranged on fixed and slightly beveled arms of the bogie body 12. It is noted that different arrangements of the wheel hubs 14a, 14b can generally be provided. The bogie body 12 further comprises a linkage 18 to arrange the bogie 10 on the bogie axle, which in turn can be fitted on the frame of the vehicle, so that the bogie 10 can be pivoted in assembled condition around a horizontal axis A which is perpendicular to the drawing plane and transverse to a vehicle's longitudinal axis (not shown).

[0030] The bogie 10 further comprises a swing arm 20, which is pivotably hinged at a first end portion 20a on the bogie body 12 and at a second end portion 20b comprises a wheel hub 22 for arrangement of a center wheel 24 between the first wheel 16a and the second wheel 16b. For reasons of clarity, all wheels 16a, 16b, and 24 are shown with dashed lines. The first wheel 14a, the second wheel 14b, and center wheel 24 are rubber air wheels.

[0031] Still further, the bogie 10 comprises a spring and/or damper element 26, which at one end portion 26a is hinged on the bogie body 12 and at the other end portion 26b is hinged on the second end portion 20b of the swing arm 20. In the present embodiment, the spring and/or damper element 26 is a hydraulic cylinder that can be pressurized with hydraulic liquid. The spring and/or damper element 26 can further be associated with a control system (not shown), which may be configured to control and/or regulate the pressurization of the hydraulic cylinder by means of said hydraulic liquid. The spring and/or damper element 26 can generally apply a force with a force component in the direction of the soil in order to pivot the swing arm 20 in the shown bearing position to push the center wheel 24 to the ground with a predetermined wheel contact force. The rotation axes of the swing arm and the rotation axes of the spring and/or damper element 26 are arranged axially parallel relative to each other. One recognizes that the swing arm 20 and the spring and/or damper element 26 relative to the linkage 18 of the bogie body 12 are mounted on the same side of the bogie body 12, i.e. the left side. Further, the swing arm 20 and the spring and/or damper element 26 are mounted on the same flange 28 of a component 30 of the bogie body 12. In the present example, the swing arm 20 is mounted by means of a rotary joint, which comprises one slide bearing bushing 32 on either side of the flange 28. However, different arrangements are also conceivable. The swing arm 20 according to the present example generally is U-shaped and forms a casing 34, in which the spring and/or damper element 26 is predominantly arranged within irrespective of the pivoting position of the swing arm 20 relative to the bogie body 12.

[0032] One recognizes that the center wheel 24 in the shown bearing position is positioned at least essentially in the center between the first and second wheel 16a, 16b which leads to a uniform force distribution of the wheels 16a, 16b, and 24 and consequently to a very low soil compaction.

[0033] Since the force of the spring and/or damper element 26 is limited due to a limited pressure in the associated hydraulic system of the hydraulic cylinder, the vertical wheel force of the center wheel 24 is limited, too. As soon as the force of the spring and/or damper element 26 is exceeded, for example because the center wheel 24 is rolling over a rock, tree or another obstacle, the center wheel 24 swings upwards and evades the obstacle so that at least one of the first and second wheels 16a, 16b keeps permanent ground contact. This prevents the vehicle weight from resting on the center wheel 24 alone. The control system can be used to control and/or regulate the hydraulic pressure of the hydraulic cylinder 26 to achieve a desired exertion of force on the center wheel 24 during the pivoting of the swing arm 20. For example, the force of the hydraulic cylinder 26 can be kept at least essentially constant during the swiveling of the swing arm 20. Alternatively, the force can be varied depending on the relative rotational position of the swing arm 20 with respect to the bogie body 12. Alternatively or additionally, the hydraulic cylinder 26 can be connected to a hydraulic circuit or hydraulic system having a pressure control valve to avoid inadmissibly high hydraulic pressures.

[0034] FIG. 2 shows a schematic side view of the bogie 10 according to the first embodiment, wherein the swing arm 20 is pivoted to a rest position. This rest position can be used in situations where the additional vertical wheel force of the center wheel 24 is not needed, for example during empty runs, travel on solid ground and the like. One recognizes that the spring and/or damper element 26 taken is completely inside the casing 34 of the swing arm 20. If the spring and/or damper element 26 comprises an active element such as a hydraulic cylinder, it is possible to actively move the center wheel 24 to the rest position, for example by selecting a respective button, switch, menu point or the like in or at the vehicle. Alternatively or additionally it may be provided that the swing arm 20 is moved manually and/or mechanically in the rest position. Further, a stop can be provided, by means of which the movability of the swing arm 20 relative to the bogie body 12 is limited. In the current example, the stop is realized by the design of the flange 28 and the swing arm 20.

[0035] FIG. 3 shows a schematic side view of the bogie 10 according to a second embodiment, wherein the swing arm 20 is pivoted to the bearing position. The general structure of the bogie 10 is known from the previous example. In contrast to the first example the spring and/or damper element 26 and the swing arm 20 are hinged on different components 30a, 30b of the bogie body 12. However, it may alternatively be provided that the spring and/or damper element 26 and the swing arm 20 are hinged on the same component 30 of the bogie 10. Further, the relative arrangement of the end portion 26a of the spring and/or damper element 26 and of the end portion 20a of the swing arm 20 differs and leads to a different lever arm and thus to a different triangle of forces of the swing arm 20, resulting in a downforce on the wheel hub 22 that depends on the relative position of the center wheel hub 22 with respect to the bogie body 12. Thus, the force exerted by the spring and/or damper element 26 on the swing arm 20 can be varied by choosing different attachment points (26a, 20a) of the spring and/or damper element 26 and the swing arm 20 on the bogie body 12. In this second embodiment, the attachment and hinging points 20a, 26a, 26b are arranged in such a way that the downward force exerted by the spring and/or damper element 26 on the wheel 24 decreases when the swing arm 20 rises, if a constant force on the spring and/or damper element 26 is applied.

[0036] FIG. 4 shows a schematic side view of the bogie 10 according to the second embodiment, wherein the swing arm 20 is pivoted to the rest position. Again, it can be recognized that the spring and/or damper element 26 is taken completely inside the casing 34 of the swing arm 20 and thus protected from environmental influences. In this uppermost position, i.e. in the rest position, almost no downforce is applied to the wheel hub 22 and the center wheel 24 anymore.

[0037] FIG. 5 shows a schematic side view of the bogie 10 according to a third embodiment, wherein the swing arm 20 is pivoted to the bearing position. The general structure of the bogie 10 is also known from the previous examples. In contrast to the first and second example, the swing arm 20 and the spring and/or damper element 26 are mounted in a V-shape on opposite sides on the bogie body 12 with respect to the linkage 18. The first end portion 20a of swing arm 20 in other words is mounted near the first wheel hub 14a, while the one end portion 26a of the spring and/or damper element 26 is mounted near the second wheel hub 14b of the bogie body 12. The swing arm 20 therefore does not form or comprise a casing 34 and can be more compactly designed. The spring and/or damper element 26 has a longer spring and/or damper travel compared to the previous examples. By pulling in the spring and/or damper element 26, the center wheel 24 can again be moved from the shown bearing position to the rest position in which the swing arm 20 and the spring and/or damper element 26 are aligned essentially linearly.

[0038] FIG. 6 shows a schematic side view of the bogie 10 according to a fourth embodiment, wherein the swing arm 20 is pivoted to the bearing position. In contrast to the previous examples it is provided that a rotation axis of the swing arm 20 and a rotation axis of the first wheel hub 14a are arranged coaxially by mounting the first end portion 20a of the swing arm 20 between the bogie body 12 and the first wheel hub 14a. Further, the end portion 26a of the spring and/or damper element 26 is mounted to a different position on the bogie body 12 compared to the third example, which results in differing lever arms.

LIST OF REFERENCE SIGNS

[0039] 10 bogie

[0040] 12 bogie body

[0041] 14a first wheel hub

[0042] 14b second wheel hub

[0043] 16a first wheel

[0044] 16b second wheel

[0045] 18 linkage

[0046] 20 arm

[0047] 20a end portion

[0048] 20b end portion

[0049] 22 wheel hub

[0050] 23 center wheel

[0051] 26 spring and/or damper element

[0052] 26a end portion

[0053] 26b end portion

[0054] 28 flange

[0055] 30 component

[0056] 30a component

[0057] 30b component

[0058] 32 bushing

[0059] 34 casing

[0060] A axis