Wheel bearing arrangement for a dual wheel assembly

BACKGROUND OF THE INVENTION

The invention relates to an axle assembly having multiple wheels at each end of an axle housing, and more specifically, the invention relates to a bearing arrangement for dual wheel assemblies in which one wheel is permitted to rotate relative to the other wheel.

Axle assemblies having dual wheels on either end of the axle have been used to increase the load bearing capability of heavy duty vehicles. Typically the pair of wheels on each end of the axle assembly are secured together so that they rotate together about an axis. Some heavy duty vehicles, such as lift trucks, undergo numerous turning maneuvers which wear the tires significantly. The tire wear is caused when the tires scrub, or drag, since the wheels that are secured together must travel different distances at the inside and outside of the turning radius. Tire wear and maintenance on heavy duty lift trucks due to scrub cost thousands of dollars annually per vehicle.

Dual wheel assembly designs have been proposed that permit the wheels to rotate relative to one another. Many designs have been developed which utilize a gear set between the wheels. As a result, very complex wheel bearing arrangements have been used which makes installation and removal of the wheels difficult. If only the outer wheel needs to be removed for repair, for example, both wheels and their associated bearing assemblies may need to be removed. That is, the wheel bearing arrangement for one wheel is not independent from the wheel bearing arrangement for the other wheel. Therefore, what is needed is a wheel bearing arrangement for a dual wheel assembly that is more modular which allows easy installation and removal of each wheel.

SUMMARY OF THE INVENTION AND ADVANTAGES

The present invention provides a dual wheel assembly for a vehicle that includes an axle assembly having an axle shaft disposed therein which defines an axis. The axle assembly has an inboard portion and an outboard portion adjacent to the inboard portion proximate to a terminal end of the axle assembly. First and second wheel hubs are supported on the outboard and the inboard portions, respectively. The first wheel hub is coupled to the axle shaft so that the first wheel hub may be driven about the axis. The second wheel hub is rotatable about the axis relative to the first wheel hub. In this manner, tire scrub is reduced since the wheel hubs may rotate at different speeds, and different directions if necessary.

A first bearing assembly is interposed between the first wheel hub and the outboard portion for supporting the first wheel hub on the outboard portion. The outboard portion has a first shoulder with the first bearing assembly abutting the first shoulder. Similarly, a second bearing assembly is interposed between the second wheel hub and the inboard portion for supporting the second wheel hub on the inboard portion, and the inboard portion has a second shoulder with the second bearing assembly abutting the second shoulder. First and second securing members are attached to the axle assembly and are adjacent to the first and the second bearing assemblies, respectively, opposite the first and the second shoulders, respectively. The first and second securing members retain the bearing assemblies against the shoulders and retain the first and the second wheel hubs on the outboard and the inboard portions, respectively. In this manner, the wheel hubs may be more easily installed and removed as units.

Accordingly, the above invention provides a wheel bearing arrangement for a dual wheel assembly that is more modular which allows easy installation and removal of each wheel.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages of the present invention can be understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1

is a cross-sectional view of a dual wheel assembly of the present invention with the wheel bearings shown schematically;

FIG. 2

is an enlarged view of one wheel bearing arrangement of the present invention;

FIG. 3

is an enlarged view of another wheel bearing arrangement of the present invention;

FIG. 4

is an enlarged view of the wheel bearing arrangement of

FIG. 2

arranged in the other hub; and

FIG. 5

is an enlarged view of the wheel bearing arrangement of

FIG. 4

arranged in the other hub.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A dual wheel assembly

10

for a vehicle is shown in FIG.

1

. The dual wheel assembly

10

includes an axle assembly

12

having an axle shaft

14

disposed therein, which defines a rotational axis A. The axle assembly

12

has an inboard portion

20

and an outboard portion

22

adjacent to the inboard portion

20

and proximate to a terminal end

24

of the axle assembly

12

. The axle assembly

12

includes an axle housing

26

that defines the inboard portion

20

. The outboard portion

22

may be defined by the axle housing

26

or by an support member, which is discussed in more detail below. The inboard portion

20

has inboard diameter that is larger than the diameter of the terminal end

24

, which facilitates ease of assembly which will be appreciated from the discussion below.

First

30

and second

32

wheel hubs are supported on the outboard

22

and the inboard

20

portions, respectively. The first wheel hub

30

is coupled to the axle shaft

14

for being driven by a drive mechanism about the axis A. The second wheel hub

32

is rotatable about the axis A relative to the first wheel hub

30

, preferably without a mechanical coupling, such as a gear set, between them. That is, the second wheel

32

is undriven and free to rotate independently of the first hub

30

. Since lift trucks have high torque requirements at the wheels, the dual wheel assembly

10

further includes a planetary gear set

36

mechanically interconnecting the axle shaft

14

and the first wheel hub

30

, in a manner known in the art, for providing torque multiplication to the first wheel hub

30

.

The planetary gear set

36

includes a removable ring gear support

38

splined to a portion

40

of the axle housing

36

to prevent rotation about the axis A. A brass bushing

41

is arranged between the terminal end

24

and the ring gear support

38

. An outer cylindrical surface of the ring gear support

38

forms the outboard portion

22

. If a planetary gear set

36

is not used, the portion

40

of the axle housing

26

may form the outboard portion

22

. A ring gear

42

is arranged on the ring gear support

38

, and a sun gear

44

is splined to the axle shaft

14

. Planetary gears

46

are supported by a cover

48

and are arranged between the sun gear

44

and the ring gear

44

. In this manner, the axle shaft

14

drives the first hub

30

through the planetary gear set

36

to achieve a multiplication of torque at the first hub

30

.

A first bearing assembly

50

, shown schematically in

FIG. 1

, is interposed between the first wheel hub

30

and the outboard portion

22

for rotationally supporting the first wheel hub

30

thereon. The outboard portion

22

has a first shoulder

52

that the first bearing assembly

50

abuts to axially locate the first bearing assembly

50

. A first securing member

54

, preferably a nut, is secured to the ring gear support

38

adjacent to the first bearing assembly

50

and opposite the first shoulder

52

to securely retain the first bearing assembly

50

in an axial position. Another nut

56

fastened to the terminal end

24

secures the ring gear support

38

and first wheel hub

30

to the axle housing

26

. A keeper

58

coacts with the nut

56

to prevent the nut

56

from loosening from the terminal end

24

. If a planetary gear set

36

is not used, the first bearing assembly

50

may be interposed between the portion

40

and the first wheel hub

30

so that the first wheel hub

30

is supported directly on the axle housing

26

. In this arrangement, the diameter of the portion

40

is smaller than the diameter of the inboard portion

20

so that the second wheel hub

32

may be easily installed and removed, as discussed below.

A second bearing assembly

60

, shown schematically in

FIG. 1

, is interposed between the second wheel hub

32

and the inboard portion

20

for rotationally supporting the second wheel hub

32

thereon. The inboard portion

20

has a second shoulder

62

with the second bearing assembly

60

abutting the second shoulder

62

to axially locate the second bearing assembly

60

. A second securing member

64

, preferably a nut, is secured to the inboard portion

20

adjacent to the second bearing assembly

60

and opposite the second shoulder

62

to securely retain the second bearing assembly

60

in an axial position along the axle housing

26

. Unlike prior art wheel bearing arrangements, the wheel bearing assembly for the innermost wheel is secured independently of the outermost wheel. That is, the pre-load of the outer bearing assembly does not affect the inner bearing assembly. In this manner, the first wheel hub

30

may be installed and removed as a unit without affecting the second wheel hub

32

.

Seals

66

,

67

are arranged between the first

30

and second

32

wheel hubs and the second wheel hub

32

and axle housing

26

, respectively, to seal the bearing area and prevent contaminants from penetrating the bearing assemblies

50

,

60

.

Detailed embodiments of the first

50

and second

60

bearing assemblies are shown in

FIGS. 2 through 5

, although bearing assemblies other than the type shown may be used. For example, a suitable ball bearing assembly may be used. The first

30

and second

32

wheel hubs each include a third shoulder

68

with each of the bearing assemblies

50

,

60

abutting the respective third shoulder

68

to axially locate the bearing assemblies

50

,

60

relative to the wheel hubs

30

,

32

. The bearing assemblies

50

,

60

typically must be axially located wheel hubs

30

,

32

in addition to axially locating the bearing assemblies

50

,

60

relative to the outboard

22

and inboard

20

portions to ensure that the wheel hubs

30

,

32

do not shift relative to the axle housing

26

.

In one embodiment shown in FIG.

2

and

FIG. 4

, the first

50

and second

60

bearing assemblies each comprise a pair of spaced apart roller bearing assemblies

70

, as well known in the art, with the third shoulder

68

interposed between the roller bearing assemblies

70

. In this manner, the outer races

71

of the bearing assemblies

70

abut the third shoulder to axially locate the bearing assemblies

70

relative to the second wheel hub. In another embodiment shown in FIG.

3

and

FIG. 5

, the first

50

and second

60

bearing assemblies each comprise a unitized bearing assembly

72

with the outer race

74

abutting the third shoulder

68

and the inner race

76

abutting the second shoulder

62

and the nut

64

. Typically, a retainer

78

is used to abut each of the unitized bearing assemblies

72

opposite the respective third shoulder

68

for locating the bearing assemblies

72

relative to its respective wheel hub.

The invention has been described in an illustrative manner, and it is to be understood that the terminology that has been used is intended to be in the nature of words of description rather than of limitation. Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.