Abstract:
A full floating inverted axle assembly having a removable axle shaft. A hub assembly includes an inner race rigidly connected to a wheel body and rotatably connected to an outer race which is in turn rigidly connected to an axle housing to enable rotation of the wheel body relative to the axle housing. A driving member is disposed within the axle housing for driving the inner race and wheel body. A removable axle shaft forms a detachable connection between the driving shaft and inner race. The removable axle shaft is externally removable from the entire axle assembly when the hub assembly is connected to the axle housing. Such an arrangement facilitates a disconnect between the driving member and inner race thereby allowing the wheel body to freely rotate, such as during towing, without having to remove the hub assembly. A brake torque member may be disposed between the inner race and axle housing to allow customized brake arrangements.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is directed to a driving axle assembly and is more particularly directed to a full floating inverted axle hub assembly with a removable axle shaft. 
     2. Description of the Related Art 
     In conventional rear axle assemblies the wheel hub is secured to the axle by a nut on the end of the axle. All axial forces on the wheel hub are directly transmitted to the axle. Furthermore, the weight of the vehicle is transmitted to the wheel hub and consequently to the axle causing a bending moment on the axle. The axle shaft, which turns on a bearing in the axle tube/housing, must then be strong and heavy to endure all these loads. This arrangement is undesirable particularly in heavy-duty truck applications. 
     In an effort to remove loads applied to the axle shafts, full floating axle assemblies were designed. Full floating axle hub assemblies provide hubs mounted on bearings directly attached to the axle housing independently of the axle shaft that drives the hub. With this arrangement the axle shaft only provides torque to drive the hub and consequently turn the wheels and does not endure vehicle weight or axial loads. However, heretofore, the prior art has failed to provide a full floating inverted axle hub assembly having an independently removable axle shaft or a replaceable brake torque plate. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an improved axle hub assembly that improves upon the related art. 
     The present invention is directed to full floating inverted axle hub assembly. An inverted hub assembly is an arrangement providing an inner race disposed within the outer race. The inverted hub assembly includes an inner race rigidly connected to a wheel body and rotatably connected to an outer race which is in turn rigidly connected to an axle housing to enable rotation of the wheel body relative to the axle housing without substantial relative motion in the other five degrees of freedom. A driving member is disposed within the axle housing for driving the inner race and wheel body. A removable axle shaft forms a detachable connection between the driving member and inner race. The removable axle shaft is externally removable from the entire axle assembly when the hub assembly is connected to the axle housing. Such an arrangement facilitates a disconnect between the driving member and inner race thereby allowing the wheel body to freely rotate, such as during towing, without having to remove the hub assembly. The full floating arrangement alleviates excessive loads placed on the driving member. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 fragmentary sectional view of the full floating inverted axle hub assembly according to the present invention. 
     FIGS. 2A &amp; 2B are schematic representations of the axle hub assembly of FIG. 1 with the removable axle in an assembled and a removed position respectively. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 is a sectional view of the preferred embodiment of the present invention. A hub assembly  1  includes an inner race  2  formed of a hollow substantially cylindrical member rotatably secured to an outer race  3  which is in turn rigidly secured to an axle housing  4 . Two tapered roller bearings  5  are disposed between the inner race  2  and the outer race  3  as may be conventionally found within the art. In the embodiment of FIG. 1, a pair of spaced apart tapered roller bearing assemblies are seated in seats formed in the radially inner surface of the outer race  3  and the outer peripheral surface of the inner race  2 . A washer  7  and threaded lock nut  8  may be employed to axially retain the bearing assemblies. The threaded lock nut  8  is simply threaded onto the end of the inner race  2  opposite the flange portion  6 . The hub assembly  1 , with the assembled inner race  2  outer race  3  and bearings  5  are then bolted to the axle housing  2  to form a rotatable connection between the inner race  2 , and flange portion  6 , with respect to the axle housing  4 . The flange portion  6  is adapted to be connected to a wheel body  19  (schematically represented in FIGS. 2A &amp; 2B) thereby establishing a rotatable connection between the wheel body  19  and the axle housing  2 . The flange portion  6  is adapted to be connected to a wheel body as is conventionally known in the art. The wheel body may include a brake drum or brake rotor. Preferably the inner race  2  and the flange portion  6  are integrally formed of a single piece of metal. However, the flange portion  6  and the inner race  2  may be made of two different steel alloys welded to one another to form an integral body. A seal (generically represented as  9  in FIG. 1) is disposed between the inner race  2  and outer race  3  adjacent an external end to contain lubricating fluid within the axle assembly. 
     In order to accommodate different types of brake arrangements, a brake torque member  10  is disposed between the outer race  3  and the axle housing  2 . The brake torque member may be formed of different sizes and shapes to accommodate different axle/wheel end designs. As can be seen in FIG. 1, the brake torque member  10  is sandwiched between the axle housing  2  and outer race  3  of the hub assembly. The brake torque member  10  is simply placed against and aligned with the corresponding surface of the axle housing  2 . The outer race  3  together with the remaining portions of the hub assembly  1  are then aligned with the axle housing  4  and brake torque member  10  and simply bolted in place via bolts  11  extending through bores formed through the outer race  3 , brake torque member  10  and axle housing  2 . Preferably, the axle housing  4  and the outer race  3  of the hub assembly  1  have a shoulder/notch interface  12  (conventionally known in the art as a pilot or spigot attachment) to facilitate easy alignment and installation. It is noted that the outer race  3  of the hub assembly can be directly secured to the axle housing  4  in embodiments not contemplating a brake torque member  10  as arranged in the presently described embodiment. In either embodiment, a gasket or other seal is disposed between the axle housing  4  and the outer race  3  to seal lubricating fluid within the axle assembly. 
     The axle housing  4  houses a driving member  14  associated with a differential assembly or other gear arrangement as is conventionally found in the art. In the present invention, like in other axle shaft arrangements, the suspension system is directly secured to the axle housing  4  and is not directly connected to the inner race  2  of the hub assembly  1  nor the wheel body  19 . Consequently, the driving member  14  does not bear any of the dead weight or dynamic loads of the vehicle. Furthermore, the driving member  14  (schematically shown in FIGS. 2A &amp; 2B) is not directly connected to the inner race  2  of the hub assembly  1 . Rather, the present invention includes a removable axle shaft  15  that is detachably connected to the driving member  14  and the inner race  2 . In the driving mode, the removable axle  15  is splined into the driving member  14  or otherwise connected thereto to form a connection there between to allow torque transfer from the driving member  14  to the removable axle  15 . The removable axle  15  is in turn removably connected to the inner race  2 . Preferably, the removable axle is splined to the inner race. The removable axle  15  has external splines formed on an end opposite the connection with the driving member  14 . The removable axle  15  is disposed within the hollow substantially cylindrical member forming the inner race  2 . The external splines  16  of the removable axle engage splines  17  formed on an inner surface  18  of the inner race  2 . The removable axle  15  has dimensions to allow the removable axle  15  to translate through the inner race  2  to facilitate removal therefrom. The removable axle  15  simply has an outer diameter less than or equal to a corresponding inner diameter of the inner race  2 . More specifically, the splines formed on the differential end of the axle shaft  15  are capable of sliding through the splines of the inner race  2 . Such an arrangement allows the removable axle  15  to be disconnected from the driving member  14  and removed from the axle hub assembly while the hub assembly is connected to the axle housing  4 . This provides the ability to selectively choose the driving state of the wheel body. When free running of the wheel body  19  is desired, such as during vehicle towing, the removable axle  15  is simply removed from the assembly. When positive driving of the wheel body  19  is desired, the removable axle shaft  15  is simply inserted in the inner race  2  of the hub assembly  1  to engage the driving member  14 . 
     To facilitate installation and removal of the removable axle shaft  15 , a retainer  20  is provided. The retainer  20  is simply a bolt, or other member, extending through the inner race  2  from the wheel body end adjacent the flange portion  6  to the removable axle  15 . The retainer  20  is simply threaded  18  to the removable axle  15 . The retainer  20  has a widened area adjacent the flange portion  6  and is simply secured thereto such as by bolts as shown in FIG.  1 . The retainer  20  is loosely threaded  18  to the driving member  14  to allow some free play rotation of the retainer  20  for alignment with the flange portion  6  of the inner race. However, the retainer  20  may be connected to the flange portion  6  of the inner race  2  in any other suitable fashion. The retainer  20  has a plug portion  28  formed within the inner race  2 . An annular seal  22  is disposed within an annular recess  23  formed in the plug portion  28  to form a seal between the plug portion  28  of the retainer  20  and the inner peripheral surface of the inner race  2 . Such an arrangement is particularly useful in arrangements contemplating a central tire inflation system. However, a more simple arrangement may be employed for the retainer  20  wherein the retainer simply has an extension to engage the removable shaft  15  to prevent axial displacement. The inner race  2  may be sealed from the external environment by placing a gasket or other seal between the retainer  20  and the flange portion  6  of the inner race  2 . 
     The retainer  20  primarily serves to hold the removable axle shaft  15  within the inner race  2  preventing axial translation. However, as previously mentioned, the retainer  20 , also serves to seal the lubricating fluid within the axle hub assembly. 
     Referring now to FIGS. 2A &amp; 2B, the axle hub assembly of the present invention is schematically represented in a driving state and a free rotating state. FIG. 2A depicts removable axle shaft  15  connected to both the driving member  14  and the inner race  2 . The inner race  2  being rigidly connected to a wheel body  19  to form a positive connection between the removable axle  15  and wheel body  19 . Thus, in the driving state, the driving member  14  rotatably drives the wheel body  19 . The removable axle shaft  15  may be splined to the driving member  14 . However, other detachable connections may be employed so long as a positive driving connection is maintained and the removable axle shaft  15  may be detached from the driving member  14  and removed through the inner race  2  of the hub assembly  1 . 
     FIG. 2B schematically depicts the present invention in a free running state. As can be seen in FIG. 2B, the removable shaft  15  is detached from the driving member  14  and removed through the inner race  2  of the hub assembly  1 . Because the removable shaft  15  is splined to the inner surface of the inner race  2  of the hub assembly  1  and has an external diameter that practically is slightly smaller than the corresponding internal diameter of the inner race  2 , the removable shaft  15  may be simply pulled through the inner race  2  and removed from the entire axle hub assembly. To remove the removable axle shaft  15  from the axle hub assembly, the retainer  20  is simply disconnected from the flange portion  6  of the inner race  2  and pulled from outside the axle hub assembly. However, in an embodiment where the retainer merely has an extension to prevent axial displacement of the removable shaft  15 , a special tool may be employed to pull the removable shaft  15  from within the inner race  2 . The retainer  20  may be equipped with a fitting to engage a slide hammer or other tool to facilitate removal of the removable axle shaft  15 . Such an arrangement allows the wheel body  19  to freely rotate such as desired during vehicle towing operations. 
     Off course, it is noted that drawing figures only depict the present invention for a single axle hub assembly leading to one driven wheel body. It is to be understood that the axle hub assembly of the present invention is employed on both sides of a differential or other gear assembly for each output shaft leading to a driven wheel body. 
     While the foregoing invention has been shown and described with reference to a preferred embodiment, it will be understood by those possessing skill in the art that various changes and modifications may be made without departing from the spirit and scope of the invention. 
     For example, the hub assembly  1  may be formed of a unitized assembly where the inner race  2 , outer race  3 , and roller elements are integrated to form a sealed, tamper-proof unitized hub assembly. The unitized hub assembly, in a pre-assembled state, is simply bolted or otherwise rigidly connected to the axle housing  4  in a single step. The removable axle shaft  15  may then be simply inserted through the unitized hub assembly to engage the driving member  14 .