Wheel bearing lubrication device and method

Abstract

The invention relates to a wheel bearing lubrication device (1) for lubricating a bearing unit in a wheel head (7) of a vehicle, the wheel bearing lubrication device (1) comprising an axle bridge (2) and a drive unit for the vehicle, which is arranged in the axle bridge (2), as well as a lubrication fluid system with lubricating fluid and a pump, which conveys the lubricating fluid through the drive unit, as well as a shaft (6) arranged axially rotatably in the axle bridge (2), and a wheel hub (8) with the bearing unit, wherein the wheel hub (8) is rotatably mounted on the axle bridge (2) via the bearing unit. where An oil reservoir is provided in the wheel hub (17), which is arranged in the wheel hub (8), wherein the oil reservoir in the wheel hub (17) is connected to the bearing unit for lubrication of the bearing unit and a connecting channel is provided between the oil reservoir in the wheel hub (17) and the lubrication fluid system, so that the pump delivers the lubrication fluid through the drive unit as well as through the connecting channel to the oil reservoir in the wheel hub (17). Furthermore, the invention relates to a method.

Description

[0001] The invention relates to a wheel bearing lubrication device for lubricating a bearing unit in a wheel head of a vehicle, the wheel bearing lubrication device comprising an axle bridge and a drive unit for the vehicle, which is arranged in the axle bridge, as well as a lubrication fluid system with lubrication fluid and a pump, which conveys the lubrication fluid through the drive unit, as well as a shaft arranged axially rotatably in the axle bridge, as well as a wheel hub with a bearing unit, wherein the wheel hub is rotatably mounted on the axle bridge via the bearing unit, and a method.

[0002] It is well known that bearings in a wheel hub need to be lubricated. Grease is primarily used for this purpose.

[0003] EP0562094B1 discloses a lubrication system in a wheel carrier device, comprising an axle journal connected to a wheel suspension component belonging to a vehicle, a wheel hub rotatably arranged on the axle journal with a hub drive in which the lubrication system provides lubrication for the hub drive, and with, in the axial direction, inner and outer bearings by which the wheel hub is mounted on the axle journal, wherein the wheel hub has a hub cap surrounding the bearings, in the interior of which an annular oil reservoir for lubricating oil circulated in the lubrication system is provided. wherein an oil collection device rigidly arranged in relation to the axle journal is arranged in the wheel cap and is designed such that, when the hub rotates, it collects oil and / or oil droplets in the oil reservoir and necessarily directs them to an annular space arranged on the outside of the axle journal, which is connected to at least one arcuate chamber arranged between the bearings in the wheel hub, from which oil can flow out through both the outer and the inner wheel bearing, wherein special oil return channels, separate from the connection with the arcuate chamber, are provided in the hub and are designed to return oil that has passed through the inner bearing to the annular oil reservoir in the axle bridge.

[0004] US20220289022A1 discloses a vehicle wheel assembly comprising a drive shaft and a hub, wherein the wheel assembly further comprises a gear cavity accommodating a gear assembly between the drive shaft and the hub, wherein the wheel assembly comprises a reservoir and wherein a circulation channel extends from the gear cavity to the reservoir, and wherein a supply channel extends from the reservoir to the gear cavity, wherein the wheel assembly further comprises a pump, wherein the pump is arranged along the circulation channel, and wherein the pump is arranged to pump lubricant from the gear cavity to the reservoir.

[0005] One object of the present invention is to provide an improved wheel bearing lubrication device for a wheel head of a vehicle, as well as an improved method.

[0006] The problem is solved by a wheel bearing lubrication device having the features of claim 1 and a method having the features of claim 10.

[0007] The dependent claims list further advantageous measures which can be suitably combined to achieve further advantages.

[0008] The problem is solved by a wheel bearing lubrication device for lubricating a bearing unit in a wheel head of a vehicle, the wheel bearing lubrication device comprising an axle bridge and a drive unit for the vehicle, which is arranged in the axle bridge, as well as a lubrication fluid system with lubrication fluid and a pump, which conveys the lubrication fluid through the drive unit, as well as a shaft arranged axially rotatably in the axle bridge, and a wheel hub with a bearing unit, wherein the wheel hub is rotatably mounted on the axle bridge via the bearing unit. where An oil reservoir is provided, which is located in the wheel hub, and which is connected to the bearing unit for lubrication of the bearing unit, and a connecting channel is provided between the oil reservoir in the wheel hub and the lubrication fluid system, so that the pump delivers the lubrication fluid through the drive unit as well as through the connecting channel to the oil reservoir in the wheel hub.

[0009] A drive unit can, for example, comprise an electric motor, a gearbox, and a differential, which are arranged in the center of the axle beam. In particular, the axle beam has two such wheel hubs, which have an analogous wheel bearing lubrication device, meaning that, for example, oil is pumped by the same pump to a first and second wheel hub to lubricate a first and second bearing.

[0010] Furthermore, the axle bridge is, for example, designed to be hollow, allowing a shaft to pass through it. Likewise, the shaft itself can be partially hollow. The term "axle bridge" can also refer to, for example, the axle housing.

[0011] The shaft is preferably designed as a flanged or side shaft. Oil is primarily used as the lubricating fluid.

[0012] According to the invention, it was recognized that conventionally driven axles, i.e., a drivetrain with an internal combustion engine and transmission, generally do not have an oil pump. In such a drivetrain, the lubrication points requiring lubrication, such as the gears and bearings, are not specifically lubricated. For lubrication, a high oil level is maintained in the axles, for example, up to approximately the center of the (flange) shaft, or a separate oil reservoir is used in the wheel hub. This ensures that the wheel bearings are always immersed in oil and thus lubricated, even during operation.

[0013] According to the invention, it was further recognized that in electrically driven axles, i.e., an axle with an integrated electric motor, i.e., a drive unit or central unit with an electric motor and a gear set, for example, a gearbox with differential, a pump is generally present for targeted oil lubrication of the lubrication points, i.e., the gears, bearings, etc., in the drive unit. Due to the forced lubrication, the overall oil level of the axle is lower than in conventional axles, which means that the wheel bearings no longer splash and are lubricated by the oil during operation.

[0014] According to the invention, it was recognized that, with a suitable design of the wheel bearing lubrication device, the pump can also be used to lubricate the wheel bearings.

[0015] For this purpose, an oil reservoir, specifically an oil basin or oil reservoir, is provided in the wheel hub, which is connected to the bearing unit for lubrication. The oil reservoir in the wheel hub ensures that there is always sufficient oil available to lubricate the wheel bearing, primarily through centrifugal force during operation. A cavity already adjacent to the bearing can be used as the oil basin.

[0016] Furthermore, according to the invention, a connecting channel is provided, which can comprise interconnected longitudinal and transverse bores, between the oil reservoir in the wheel hub and the lubrication fluid system, so that the pump can convey the lubrication fluid through the drive unit as well as through the connecting channel to the oil reservoir in the wheel hub. The connecting channel can be achieved by means of strategically placed bores or pipes from the lubrication system of the drive unit to the wheel head.

[0017] According to the invention, the oil pump of the drive unit / central unit is also used to lubricate the wheel head.

[0018] In a further development, the connecting channel includes an axial longitudinal bore as a lubrication fluid channel, which is inserted axially into the shaft.

[0019] The axial lubrication channel can be formed as an axial bore, for example, a longitudinal bore, in the shaft. Alternatively, the shaft can already be hollow or partially hollow. In particular, the bore, i.e., the lubrication channel, is arranged centrally in the shaft for reasons of rotational symmetry.

[0020] In a further embodiment, the connecting channel comprises at least one lubricating fluid transfer channel, in particular an oil transfer channel, for example an oil bore, wherein the lubricating fluid transfer channel is arranged in the axle bridge for supplying the lubricating fluid from the lubrication system of the drive unit via the pump, and wherein an annular channel, which is arranged radially above the shaft, is further provided, and wherein the lubricating fluid transfer channel opens into the annular channel for pumping the lubricating fluid from the lubricating fluid transfer channel into the annular channel. The annular channel is formed by two sealing rectangular rings, which are arranged axially spaced apart between the axle bridge and the shaft. This means that the annular channel is created by the distance between the axle bridge and the shaft and by two seals. The annular channel facilitates the transfer of oil from the axle bridge to the shaft.

[0021] In a further embodiment, the connecting channel comprises at least one first transverse bore, in particular also four transverse bores arranged at 90 degrees angle, which extend from the annular channel to the axial lubricating fluid channel for conveying lubricating fluid from the lubricating fluid transfer channel into the lubricating fluid channel.

[0022] In a further embodiment, a lubricating fluid accumulator, i.e., oil reservoir, is provided, wherein the lubricating fluid accumulator is arranged in the axle bridge, wherein the lubricating fluid accumulator is connected to the oil reservoir in the wheel hub, here the oil basin, so that lubricating fluid flows into the oil reservoir in the wheel hub via the lubricating fluid accumulator.

[0023] In a further development, the vehicle has a floor facing the roadway, with the lubricating fluid reservoir integrated into the axle beam on the side facing the floor, i.e., at the lowest point in the axle beam. The oil reservoir in the wheel hub and the lubricating fluid reservoir ensure that there is always enough lubricating fluid, in this case oil, to lubricate the bearing unit.

[0024] The oil reservoir in the wheel hub can be an existing cavity within the wheel hub. The oil reservoir in the wheel hub and the lubricating fluid storage tank can be connected by a bore.

[0025] Due to its placement at the lowest point in the axle housing, the oil flows from the shaft to the lubricant reservoir by centrifugal force or gravity. The oil then flows, again driven by centrifugal force / gravity, into the radially lower oil reservoir in the wheel hub, which is directly connected to the bearing unit.

[0026] In a further embodiment, the connecting channel comprises at least a second transverse bore, wherein the at least one second transverse bore is arranged in the shaft for fluidic connection of the axial lubricant channel in the shaft with the lubricant reservoir.

[0027] In particular, four transverse bores are incorporated around the circumference of the shaft, spaced at 90° intervals. This allows sufficient oil to flow from the lubrication channel into the lubrication reservoir.

[0028] Furthermore, such a second transverse bore can also lead directly into the oil reservoir in the wheel hub if no separate lubricating fluid reservoir is present.

[0029] In a further development, the lubricant reservoir is connected to the drive unit's lubricant system via a return channel. This ensures oil overflow / return into the axle's interior. Specifically, the shaft is radially spaced from the axle bridge, so that the overflow channel is formed by this distance.

[0030] Furthermore, the problem is solved by a method for lubricating a bearing unit in a wheel head of a vehicle comprising the following steps: - Providing an axle bridge and a drive unit for a vehicle, which is arranged in the axle bridge, as well as a lubrication fluid system with lubricating fluid and a pump which conveys the lubricating fluid through the drive unit, as well as a shaft axially rotatable in the axle bridge, and a wheel hub with a bearing unit, wherein the wheel hub is rotatably mounted on the axle bridge via the bearing unit, - Providing an oil reservoir in the wheel hub, which is arranged in the wheel hub and which is fluidically connected to the bearing unit for lubrication of the bearing unit, - Providing a connecting channel between the oil reservoir in the wheel hub and the lubrication fluid system, - Pumping the lubricating fluid from the lubricating fluid system through the connecting channel to the oil reservoir in the wheel hub.

[0031] The advantages of the wheel bearing lubrication device can be transferred to the method. In particular, the method can be carried out on the wheel bearing lubrication device according to the invention.

[0032] In particular, a lubricating fluid accumulator is provided, wherein the lubricating fluid accumulator is arranged in the axle bridge, wherein the lubricating fluid accumulator is connected to the oil reservoir in the wheel hub and the lubricating fluid channel for the flow of the lubricating fluid from the lubricating fluid channel via the lubricating fluid accumulator into the oil reservoir in the wheel hub.

[0033] Especially during commissioning, the oil reservoir in the wheel hub and the lubricant accumulator are manually filled with lubricant. This means that before the axle is operated for the first time, the wheel head is also filled initially, for example via an oil filler screw, to ensure that sufficient lubricating oil is present in the wheel head from the start.

[0034] Further features and advantages of the present invention will become apparent from the following description with reference to the accompanying figures. These show: Fig. 1: An exemplary and schematic representation of a wheel bearing lubrication device according to the invention, Fig. 2: a connection between an oil reservoir in the wheel hub and an oil transfer channel, Fig. 3: a lubrication of a wheel head according to the invention.

[0035] Fig. Figure 1 shows, by way of example and schematically, a wheel bearing lubrication device 1 according to the invention for a vehicle.

[0036] The wheel bearing lubrication device 1 has an axle bridge 2, also called an axle housing. Furthermore, the wheel bearing lubrication device 1 includes a drive unit, which here comprises at least an electric motor 3, a gearbox 4 and a differential 5.

[0037] The electric motor 3, the gearbox 4 and the differential 5 are arranged in a common housing, which forms an axially central component of the axle bridge 2.

[0038] Furthermore, the wheel bearing lubrication device 1 comprises a first shaft 6 ( Fig. 2), here a side or flange shaft, with a first wheel head 7 ( Fig. 3).

[0039] The wheel bearing lubrication device 1 can have a second shaft and a second wheel hub (not shown). The electric motor 3 transmits torque and rotational speed to the gearbox 4 via the motor shaft of the electric motor 3 or via an input shaft (not shown) of the gearbox 4, and via the gearbox 4 to the differential 5. The differential 5 distributes the transmitted torque and rotational speed via the first shaft 6 to the first wheel hub 7. Furthermore, the differential 5 can transmit the transmitted torque and rotational speed via the second shaft to the second wheel hub. The electric motor 3, the gearbox 4, and the differential 5 can be arranged coaxially with the first shaft 6 and the second shaft in the axle housing 2.

[0040] The first wheel head 7 has a wheel hub 8 ( Fig. 3) with a bearing unit. The wheel hub 8 is rotatably mounted on the axle bridge 2 or on a part of the axle bridge 2 by the bearing unit.

[0041] The bearing unit here is designed as a wheel bearing 18 in the form of a tapered roller bearing, which supports the wheel hub 8 against the axle bridge 2.

[0042] The shaft 6 has a front flange 9 ( Fig. 3) on. The wheel hub 8 is rotatably connected to the shaft 6 via the end flange 9 of the shaft 6. Furthermore, several wheel bolts 10 are provided, whereby a vehicle wheel of the vehicle can be rotatably attached to the wheel hub 8 or shaft 6.

[0043] Furthermore, the drive unit has at least one lubrication fluid system comprising at least one oil sump (not shown) and at least one pump (not shown) which pumps the oil from the oil sump through part or all of the drive unit for lubricating / cooling the entire drive unit or parts of the drive unit.

[0044] The oil sump and / or the pump can also be located outside the drive unit / axle bridge 2, but must be connected to the drive unit. The pump circulates the oil to lubricate the drive unit or at least to lubricate parts of the drive unit through the drive unit.

[0045] According to the invention, an oil reservoir is located in the wheel hub 17 ( Fig. 3), here an oil basin is present in the wheel hub 8, which is connected to the pump of the drive unit.

[0046] Fig. Figure 2 shows a first part of a connection between the oil reservoir in the wheel hub 17 and an oil transfer channel 11.

[0047] To convey oil from the oil sump or lubrication system in the drive unit to the wheel hub 7, an oil transfer channel 11, for example a radial bore, is provided in the axle bridge 2. This extends to the shaft 6 and terminates there in an annular channel 12. The annular channel 12 is formed by two sealing rectangular rings 13, which are arranged sealingly between the axle bridge 2 and the shaft 6.

[0048] Furthermore, an axial channel is provided as a lubrication fluid channel 15 in the shaft 6, which is designed, for example, as a longitudinal bore in the axial direction A in the shaft 6.

[0049] Furthermore, a first transverse bore 14 extends through the shaft 6 from the annular channel 12 to the lubrication fluid channel 15 in the shaft 6. In particular, four transverse bores are provided, arranged circumferentially at 90° angles to introduce sufficient oil into the lubrication fluid channel 15 of the shaft 6. Through the connection with the pump, oil flows from the drive unit's lubrication fluid system via the oil transfer channel 11, i.e., the radial bore in the axle bridge 2, into the annular channel 12 and then via the four transverse bores 14 into the lubrication fluid channel 15 of the shaft 6 (arrows 16 indicate flow direction).

[0050] Fig. Figure 3 shows the lubrication of wheel head 7.

[0051] Furthermore, the oil reservoir in the wheel hub 17, here an oil basin, is located in the wheel head 7. The oil reservoir in the wheel hub 17 is fluidically connected to the bearing unit, here the wheel bearings 18. A cavity adjacent to the wheel bearings 18 can serve as the oil reservoir in the wheel hub 17, thus facilitating lubrication of the wheel bearing 18 by oil from the oil reservoir in the wheel hub 17.

[0052] Furthermore, the vehicle has a floor that faces a roadway (street).

[0053] Furthermore, an oil reservoir 19 is planned.

[0054] The oil reservoir 19 is arranged in the axle bridge 3, wherein the oil reservoir in the axle bridge 19 is connected to the oil reservoir in the wheel hub 17, so that oil first flows into the oil reservoir in the axle bridge 19 and then into the oil reservoir in the wheel hub 17 (transverse bore for connecting the oil reservoirs 23).

[0055] The oil reservoir in the axle bridge 19 is located on the side of the axle bridge 2 facing the vehicle floor, i.e., at the lowest point, so that the oil flows from the lubrication channel 15 to the oil reservoir in the axle bridge 19 with little or no pressure. Due to centrifugal force / gravity, the oil then flows from the oil reservoir in the axle bridge 19 into the oil reservoir in the wheel hub 17 and from there into the bearing unit or wheel bearing 18.

[0056] This means that, from a fluid dynamics perspective (i.e., from the direction of flow), the oil reservoir in the axle bridge 19 is located in front of the oil reservoir in the wheel hub 17.

[0057] The oil reservoir in the axle bridge 19 and the oil reservoir in the wheel hub 17 ensure that there is always sufficient oil available.

[0058] Furthermore, a second transverse bore 20 is provided as a connecting bore from the lubrication fluid channel 15 to the oil reservoir in the axle bridge 19 in the shaft 6, for example as a radial bore.

[0059] In particular, four second transverse bores 20 are provided circumferentially in the shaft 6 at 90° intervals. This allows sufficient oil to flow from the lubrication channel 15 into the oil reservoir in the axle bridge 19. The lubrication channel 15 extends in axial direction A at least to the beginning of the oil reservoir in the axle bridge 19, but preferably beyond.

[0060] Due to the radial spacing of the shaft 6 from the axle bridge 2, oil also flows as lubrication between the shaft 6 and the axle bridge 2 along the wheel head 7, i.e., up to the end flange 9. Furthermore, this radial spacing allows an oil overflow / oil return channel 21 to be formed for the return of the oil into the axle interior, i.e., to the lubrication fluid system of the drive unit.

[0061] This means that the oil from the drive unit's lubrication system is pumped by the pump to the oil transfer channel 11 and the annular channel 12, as well as the first transverse bore 14, into the lubrication channel 15, and then through this channel and the fluid channels 20 to the oil reservoir in the axle bridge 19. The oil then flows from the oil reservoir in the axle bridge 19 to the oil reservoir in the wheel hub 17 and lubricates the wheel bearings 18 from there. Furthermore, oil can also flow between the axle bridge 2 and the shaft 6 to the end flange 9 in the wheel head 7 and from there also to the wheel bearing 18.

[0062] This shows Fig. 3 the oil chamber filled with lubricating oil 22.

[0063] When the oil reservoir in the wheel hub 17 as well as the oil reservoir in the axle bridge 19 overflows, the oil flows back into the lubrication fluid system of the drive unit between axle bridge 2 and shaft 6.

[0064] Opposite the wheel head 7, a second wheel head may be present, with a second wheel bearing lubrication device, which may be designed analogously.

[0065] This allows both the first wheel head 7 and the second wheel head to be lubricated with oil supplied by the same pump.

[0066] The wheel bearing lubrication device 1 according to the invention allows the oil pump of the central unit, here the drive unit, to also be used for lubricating the wheel head. Reference symbol list 1 Wheel bearing lubrication device 2 axle bridge 3 Electric motor 4 gearboxes 5 Differential 6 wave 7 Wheel head 8 wheel hub 9 Front flange 10 wheel bolts 11 Oil transfer channel 12 Ring channel 13 rectangular rings 14 First cross bore 15 Lubricating fluid channel 16 Flow direction 17 Oil reservoir in the wheel hub 18 wheel bearings 19 Oil reservoir in the axle bridge 20 Second transverse bore 21 Oil return channel 22 Oil room 23 Transverse boreholes for connecting the oil reservoirs QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] EP 0562094B1

[0003] US 20220289022A1

[0004]

Claims

[1] Wheel bearing lubrication device (1) for lubricating a bearing unit in a wheel head (7) of a vehicle, the wheel bearing lubrication device (1) comprising an axle bridge (2) and a drive unit for the vehicle, which is arranged in the axle bridge (2) and a lubrication fluid system with lubrication fluid and a pump, which conveys the lubrication fluid through the drive unit and a shaft (6) arranged axially rotatably in the axle bridge (2), and a wheel hub (8) with the bearing unit, wherein the wheel hub (8) is rotatably mounted on the axle bridge (2) via the bearing unit, characterized by, that an oil reservoir is provided in the wheel hub (17), which is arranged in the wheel hub (8), wherein the oil reservoir in the wheel hub (17) is connected to the bearing unit for lubrication of the bearing unit and a connecting channel is provided between the oil reservoir in the wheel hub (17) and the lubrication fluid system, so that the pump delivers the lubrication fluid through the drive unit as well as through the connecting channel to the oil reservoir in the wheel hub (17). [2] Wheel bearing lubrication device (1) according to claim 1, characterized by , that the connecting channel includes an axial lubricating fluid channel (15) which is inserted axially into the shaft (6). [3] Wheel bearing lubrication device (1) according to claim 2, characterized by , that the axial lubrication fluid channel (15) is provided as a bore in the shaft (6). [4] Wheel bearing lubrication device (1) according to claim 2 or 3, characterized by, that the connecting channel comprises at least one lubricating fluid transfer channel and wherein the lubricating fluid transfer channel is arranged in the axle bridge (2) for supplying the lubricating fluid from the lubrication system of the drive unit by the pump and wherein furthermore an annular channel (12) is provided, which is arranged radially above the shaft (6) and wherein the lubricating fluid transfer channel opens into the annular channel (12) for pumping the lubricating fluid from the lubricating fluid transfer channel into the annular channel (12). [5] Wheel bearing lubrication device (1) according to claim 4, characterized by , that the connecting channel includes at least a first transverse bore (14) which extends from the annular channel (12) to the axial lubricating fluid channel (15) for the passage of lubricating fluid from the lubricating fluid transfer channel into the lubricating fluid channel (15). [6] Wheel bearing lubrication device (1) according to any one of the preceding claims 2 to 5, characterized by, that a lubricating fluid accumulator is provided, wherein the lubricating fluid accumulator is arranged in the axle bridge (2), wherein the lubricating fluid accumulator is connected to the oil reservoir in the wheel hub (17) and the lubricating fluid channel (15), so that lubricating fluid flows into the oil reservoir in the wheel hub (17) via the lubricating fluid accumulator. [7] Wheel bearing lubrication device (1) according to claim 6, characterized by , that the vehicle has a vehicle floor which faces a roadway and wherein the lubricating fluid reservoir is installed in the axle bridge (2) on a side facing the vehicle floor. [8] Wheel bearing lubrication device (1) according to one of the preceding claims 6 or 7, characterized by , that the connecting channel comprises at least a second transverse bore, wherein the at least one second transverse bore (20) is arranged in the shaft (6) for fluidic connection of the axial lubricant channel (15) in the shaft (6) with the lubricant reservoir. [9] Wheel bearing lubrication device (1) according to any one of the preceding claims 6 to 8, characterized by that a return channel is provided which connects the lubricant reservoir to the lubricant system of the drive unit. [10] Method for lubricating a bearing unit in a wheel head (7) of a vehicle comprising the steps: - Providing an axle bridge (2) and a drive unit for a vehicle, which is arranged in the axle bridge (2), as well as a lubrication fluid system with lubricating fluid and a pump which conveys the lubricating fluid through the drive unit, as well as a shaft (6) axially rotatably mounted in the axle bridge (2), and a wheel hub (8) with a bearing unit, wherein the wheel hub (8) is rotatably mounted on the axle bridge (2) via the bearing unit, - Providing an oil reservoir in the wheel hub (17), which is arranged in the wheel hub (8) and which is fluidically connected to the bearing unit for lubrication of the bearing unit, - Providing a connecting channel between the oil reservoir in the wheel hub (17) and the lubrication fluid system, - Pumping by the pump of the lubricating fluid from the lubricating fluid system through the connecting channel to the oil reservoir in the wheel hub (17). [11] Method according to claim 10, characterized by , that a lubricating fluid accumulator is provided, wherein the lubricating fluid accumulator is arranged in the axle bridge (2), wherein the lubricating fluid accumulator is connected to the oil reservoir in the wheel hub (17) and the lubricating fluid channel (15) for the flow of the lubricating fluid via the lubricating fluid accumulator into the oil reservoir in the wheel hub (17). [12] Method according to claim 11, characterized by, that during commissioning a manual filling of the oil reservoir in the wheel hub (17) and the lubricant accumulator with lubricant is carried out.

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