Wheel end assembly

A wheel mount for a wheel comprises a spindle, a hub for surrounding the spindle and a bearing assembly interposed between the spindle and the hub. The spindle extends from an end of an axle of a vehicle and has a generally decreasing diameter from its proximal end to its distal end. The spindle is provided with a pair of lands near the ends of the spindle for receiving bearings, and has bearing retainers near the respective ends also, the distal retainer being removably attached. These inboard and outboard bearing retainers define an axial bearing space. The hub has a central aperture with an inboard land and an outboard land provided on an internal surface of the central aperture, also for receiving bearings. The bearing assembly comprises an inboard bearing and an outboard bearing in spaced apart relationship within the axial bearing space. The inboard bearing has an internal diameter larger than the internal diameter of the outboard bearing. The bearing assembly further has a conical shim placed in frictional fit between the cone portions of the inboard and outboard bearings and holding the respective bearings in the spaced apart relationship.

The present invention relates to an improved wheel end assembly for a 
vehicle. More particularly, the present invention relates to an improved 
wheel end assembly which provides a reduced-maintenance capability by 
incorporating both the wheel bearing and the lubrication seal within the 
present confines provided for the wheel bearing. More particularly, the 
present invention relates to a wheel end assembly for a vehicle having the 
inboard and outboard wheel bearing assemblies positioned on the spindle 
such that the outboard wheel bearing has a smaller diameter than the 
inboard wheel bearing. 
BACKGROUND OF THE ART 
In the vehicle heavy axle industry, it is necessary to provide wheel ends 
for both non-driven and driven wheels. Because of the need for 
interchanging tires and wheel hubs on these axles, it is necessary that 
certain industry standards be provided with the spindles for both driven 
and non-driven wheels. Current wheel seal technology generally uses oil 
lubrication and warranty problems relating to the wheel seal are 
significant in certain situations, particularly with regard to seal 
lubrication leakage. Some known designs present features which address 
bearing endplay/preload conditions, and these help to improve seal life. 
However, if the seal can be integrated with the bearing structure, the 
seal will be dimensionally more stable and controlled, and provide better 
protection from service and environmental conditions. 
An objective not believed to be achieved by the prior art is the 
integration of the wheel seal and the wheel bearing within the same 
dimensional confines as the existing industrial standard wheel bearing, as 
well as use of grease for lubrication rather than oil. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide a wheel end 
assembly where the wheel seal is integrated with the wheel bearing and 
contained within the same dimensional confines as the existing industrial 
standard wheel bearing. It is a further object to provide such a wheel end 
assembly having grease lubrication rather than oil lubrication. These and 
other objects of the invention are provided by a mount for a wheel of a 
vehicle comprising a spindle, a hub and a bearing assembly. The spindle 
extends from an end of an axle and generally decreases in diameter from a 
proximal end thereof to a distal end thereof. The spindle is provided with 
an inboard land near the proximal end and an outboard land near the distal 
end and has an inboard bearing retainer near the proximal end and an 
outboard bearing retainer near the distal end. These inboard and outboard 
bearing retainers define an axial bearing space. The hub surrounds the 
spindle, and has a central aperture with an inboard land and an outboard 
land provided on an internal surface of the central aperture. The bearing 
assembly is interposed between the spindle and the hub. It has an inboard 
bearing and an outboard bearing in spaced apart relationship within the 
axial bearing space, the inboard bearing having an internal diameter 
larger than an internal diameter of the outboard bearing and with a 
conical spacing shim in an interference fit between the cone portions of 
the inboard and outboard bearings.

DETAILED DESCRIPTIONS OF THE INVENTION 
FIGS. 1 and 2 show wheel mounts as known in the existing art. FIG. 1 shows 
the lower half of the wheel mount 100 for a non-driven axle of a vehicle, 
such as a front steer axle of a trailer. Although the top half of the 
wheel mount is not shown, it will be understood that the top half is a 
mirror image of the lower half, since axis A provides an axis of symmetry 
for the wheel mount and the associated structures. Similarly, FIG. 2 shows 
the lower half of the wheel mount 150 for a driven axle of the same type 
of vehicle. As with FIG. 1, axis B provides an axis of symmetry, so 
features of the upper half will be known to be mirror images of those 
shown in the lower half. 
Wheel mount 100 has substantially solid axle spindle 102 which extends from 
the end of the vehicle axle (not shown), with a proximal end 104 of the 
spindle affixed to the vehicle and a distal end 106 unaffixed. Since wheel 
mount 100 is for a non-driven axle of the vehicle, there is no need to 
transfer drive torque through the axle to the wheel through a hub 108, so 
spindle 102 does not rotate and provides a site for rotation of the hub. 
Several features of the spindle 102 are notable. The spindle 102 is 
generally decreasing in diameter from proximal end 104 to distal end 106, 
but a pair of flat lands for mounting of the hub 108 are provided. The 
first of these is an inboard land 110, positioned towards the proximal end 
104 and the second is an outboard land 112, positioned towards the distal 
end 106. Because of the decreasing diameter from the proximal end to the 
distal end, the diameter of the spindle at the outboard land is notably 
smaller than the diameter at the inboard land. At the end of the inboard 
land 110 towards the proximal end 104 of the spindle, a step increase in 
the spindle diameter occurs, providing a shoulder 114 in the spindle at 
the inboard end of the inboard land. Typically, this step increase will be 
a machined feature of the spindle, and is intended to serve as a means for 
retaining an inboard bearing mounted in the hub, particularly to prevent 
axial movement of the inboard bearing toward the proximal end of the 
spindle. As such, it completes the bearing seat provided by the inboard 
land. The outboard end of the outboard land 112, that is, the end nearer 
or towards the distal end 106, will be adapted to receive a device for 
retaining a bearing pressed into the hub when a wheel assembly is mounted 
on the spindle. Typically, the adaptation to the spindle will be the 
placement of threading at the distal end to allow reception of a nut, a 
washer and nut or a combination of a washer, a nut and a locking means, 
such as a cotter pin. It is this combination which is indeed shown in FIG. 
1 and designated as reference numeral 116. 
When the inboard and outboard bearing retainers 114, 116, respectively, are 
in place and a hub with inboard and out board bearings 118, 120, 
respectively, is mounted on and secured to the spindle, the facing 
surfaces of the respective retainers 114, 116 serve to define an axial 
bearing space within which the bearings 118, 120 are constrained from 
axial movement, although it will be noted that there is no constraint near 
the spindle restricting or constraining axial movement of the bearings 
towards each other. 
Having already been introduced, further features the hub 108 are now 
described. The hub is an annular structure with a central aperture 122 
therethrough, the axis of the hub being coincident with axis A of the 
spindle 102 when the hub is mounted on the spindle, as shown in FIG. 1. 
The major portion of the hub body runs axially along the spindle and 
extends along the spindle approximately the same length as the axial 
bearing space. A radially extending flange 124 is provided with means for 
affixing a wheel. A first end of the central aperture is provided with a 
bore 126 which serves as an inboard land when the hub is mounted on the 
spindle and the opposite second end of the hub is provided with a bore 128 
which serves as an outboard land. These bores 126, 128 are on the internal 
surface of the central aperture and each provides a shoulder 130, 132, 
respectively, at the base of the bore internal to the hub. Each of the 
bores 126, 128 are sized in terms of depth and diameter to permit press 
fitting of the bearings 118, 120 into the bore. The shoulders 130, 132 
provide a constraint to axial movement of the respective bearings being 
held. 
The bearings 118, 120 are interposed between the spindle 102 and the hub 
108 to provide for rotation of the hub upon the spindle. Each of the 
bearings comprises a cylindrical cone having an outer raceway, a 
cylindrical cup with an inner raceway and a plurality of tapered rollers 
circumferentially spaced in a cage mounted in the raceways, as is known in 
the prior art. The cone portion of each bearing is sized to frictionally 
engage the spindle 102 at one of the lands 110,112 provided thereon and 
the cup portion is sized for being press fit into frictional engagement 
with one of the bores 126,128 at the land in the central aperture of the 
hub presented by the bore. As shown in FIG. 1, the hub 108 is further 
provided with an annular lubrication seal 134, which is frictionally 
fitted into bore 126 after the insertion of the bearing 118. The 
particular lubrication seal shown in FIG. 1 is an elastomeric type of lip 
seal which extends axially from the bearing 118 such that its lip bears on 
the spindle axially inboard of the shoulder 114. The outer diameter of the 
seal 134 is frictionally fitted against bore 126 in which the inboard 
bearing is mounted, although inboard of the bearing. Because of the 
decreasing diameter of the spindle 102 as it extends outwardly from its 
proximal end 104, outboard bearing 120 is smaller in both internal 
diameter and external diameter than inboard bearing 118. 
A last feature noted in the prior art wheel mount 100 as shown in FIG. 1 is 
the provision of a distal end cap 136 to the mount. This end cap 136 would 
not normally be in place during the placement of the hub 108 on the 
spindle 102, but once the hub, with its frictionally engaged bearings, is 
seated upon the spindle and the washer, nut and locking device comprising 
the outboard bearing retainer are fastened in place, the end cap may be 
fixed in place. Typically, the cap 136 is held in place by a plurality of 
fasteners 138 passing through circumferentially spaced apertures 140 in 
the cap into corresponding apertures 142 in the hub. Since the end cap 136 
effectively seals off the distal end of the outboard bearing, the 
placement of the end cap effectively forms a lubrication reservoir which 
includes the interior 144 of the end cap and the internal portion 146 of 
the central aperture between the bearings 118,120. 
Attention is now directed to wheel mount 150 as shown in FIG. 2. Instead of 
having a substantially solid axle spindle as in the non-driven axle, the 
driven axle wheel mount 150 provides a hollow spindle 152 which extends 
from the end of the vehicle axle, with a proximal end 154 of the spindle 
affixed to the vehicle and a distal end 156 unaffixed. Internal to the 
spindle 152, a drive axle 153 provides drive torque to the hub 158, as 
will be described below. Spindle 152, however, does not rotate and 
provides a site for rotation of the hub 158. Spindle 152 is generally 
decreasing in diameter from proximal end 154 to distal end 156, but a pair 
of flat lands for mounting of the hub 158 are provided along the length. 
The first of these is an inboard land 160, positioned towards the proximal 
end 154 and the second is an outboard land 162, positioned towards the 
distal end 156. At the end of the inboard land 160 towards the proximal 
end 154 of the spindle, a step increase in the spindle diameter occurs, 
providing a shoulder 164 in the spindle at the inboard end of the inboard 
land. Typically, this step increase will be a machined feature of the 
spindle, and is intended to serve as a means for retaining an inboard 
bearing mounted in the hub, particularly to prevent axial movement of the 
inboard bearing toward the proximal end of the spindle. As such, it 
completes the bearing seat provided by the inboard land. The outboard end 
of the outboard land 112, that is, the end nearer or towards the distal 
end 156, will be adapted to receive a device for retaining a bearing 
pressed into the hub when a wheel assembly is mounted on the spindle. 
Typically, the adaptation to the spindle will be the placement of 
threading at the distal end to allow reception of a nut, a washer and nut 
or a combination of a washer, a nut and a locking means, such as a cotter 
pin. It is this combination which is indeed shown in FIG. 2 and designated 
as reference numeral 166. 
When the inboard and outboard bearing retainers 164, 166, respectively, are 
in place and a hub 158 with inboard and out board bearings 168, 170, 
respectively, is mounted on and secured to the spindle 152, the facing 
surfaces of the respective retainers 164, 166 serve to define an axial 
bearing space within which the bearings 168, 170 are constrained from 
axial movement. As in the non-driven axle case above, there is no 
constraint near the spindle restricting or constraining axial movement of 
the bearings towards each other. 
Hub 158 is an annular structure with a central aperture 172 therethrough, 
the axis of the hub being coincident with axis B of the spindle 152 when 
the hub is mounted on the spindle, as shown in FIG. 2. The major portion 
of the hub body runs axially along the spindle and extends along the 
spindle approximately the same length as the axial bearing space. A 
radially extending flange 174 is provided with means for affixing a wheel. 
A first end of the central aperture 172 is provided with a bore 176 which 
serves as an inboard land when the hub is mounted on the spindle and the 
opposite second end of the hub is provided with a bore 178 which serves as 
an outboard land. These bores 176, 178 are on the internal surface of the 
central aperture and each provides a shoulder 180, 182, respectively, at 
the base of the bore internal to the hub. Each of the bores 176, 178 are 
sized in terms of depth and diameter to permit press fitting of the 
bearings 168, 170 into the bore. The shoulders 180, 182 provide a 
constraint to axial movement of the respective bearings being held. 
The bearings 168, 170 are interposed between the spindle 152 and the hub 
158 to provide for rotation of the hub upon the spindle. Each of the 
bearings 168, 170 comprises a cylindrical cone having an outer raceway, a 
cylindrical cup with an inner raceway and a plurality of tapered rollers 
circumferentially spaced in a cage mounted in the raceways, as is known in 
the prior art. The cone portion of each bearing is sized to frictionally 
engage the spindle 152 at one of the lands 160, 162 provided thereon and 
the cup portion is sized for being press fit into frictional engagement 
with one of the bores 176, 178 at the land in the central aperture of the 
hub presented by the bore. As shown in FIG. 2, the hub 158 is further 
provided with an annular lubrication seal 184, which is frictionally 
fitted into the inboard end of the central aperture 172 after the 
insertion of the bearing 168. The particular lubrication seal 184 shown in 
FIG. 2 is an elastomeric type of lip seal which extends axially from the 
bearing 168 such that its lip bears on the spindle axially inboard of the 
shoulder 164. The outer diameter of the seal 184 is frictionally fitted 
against a bore 185 in hub 158 which is external of and larger than bore 
176 in which the inboard bearing is mounted. Because of the decreasing 
diameter of the spindle 152 as it extends outwardly from its proximal end 
154, outboard bearing 170 is smaller in both internal diameter and 
external diameter than inboard bearing 168. 
Because the wheel mount 150 is on a driven axle, a drive hub 186 is used to 
connect the drive axle 187 internal to the hollow spindle 152 to the wheel 
hub 158. This drive hub 186 would not normally be in place during the 
placement of wheel hub 158 on the spindle 152, but once the wheel hub, 
with its frictionally engaged bearings 168, 170, is seated upon the 
spindle and the washer, nut and locking device comprising the outboard 
bearing retainer 166 are fastened in place, the drive hub 186 may be fixed 
in place. Typically, the drive hub 186 is held in place by a plurality of 
bolts 188 which extend outwardly from wheel hub 158 through 
circumferentially spaced apertures 190 in the drive hub and are secured by 
a corresponding plurality of nuts (not shown). Since the drive hub 186 
effectively seals off the distal end of the outboard bearing 170, the 
placement of the drive hub effectively forms a lubrication reservoir which 
includes the interior 194 of the end cap and the internal portion 196 of 
the central aperture between the bearings 168, 170. 
Attention is now directed to FIGS. 3 and 4, which show wheel mounts of the 
present invention. FIG. 3 shows the lower half of a wheel mount 200 for a 
non-driven axle of a vehicle, such as a trailer. Although the top half of 
the wheel mount is not shown, it will be understood that the top half is a 
mirror image of the lower half, since axis A provides an axis of symmetry 
for the wheel mount and the associated structures. Similarly, FIG. 4 shows 
the lower half of the wheel mount 250 for a driven axle of the same type 
of vehicle. As with FIG. 3, axis B provides an axis of symmetry, so 
features of the upper half will be known to be mirror images of those 
shown in the lower half. 
Wheel mount 200 has substantially solid axle spindle 102 exactly as 
described in association with FIG. 1, since an objective of the present 
invention is to improve the existing wheel mount while modifying as few of 
the existing parts as necessary. Spindle 102 has a proximal end 104 
affixed to the vehicle and a distal end 106 unaffixed. Spindle 102 does 
not rotate and provides a site for rotation of the hub 108. As in the 
prior art, spindle 102 is generally decreasing in diameter from proximal 
end 104 to distal end 106, but a pair of flat lands for mounting of the 
hub 108 are provided. The first of these is an inboard land 110, 
positioned towards the proximal end 104 and the second is an outboard land 
112, positioned towards the distal end 106. Because of the decreasing 
diameter from the proximal end to the distal end, the diameter of the 
spindle at the outboard land is notably smaller than the diameter at the 
inboard land. At the end of the inboard land 110 towards the proximal end 
104 of the spindle, a step increase in the spindle diameter occurs, 
providing a shoulder 114 in the spindle at the inboard end of the inboard 
land, which is intended to serve as a means for retaining an inboard 
bearing mounted in the hub, particularly to prevent axial movement of the 
inboard bearing toward the proximal end of the spindle. As such, it 
completes the bearing seat provided by the inboard land. The outboard end 
of the outboard land 112, that is, the end nearer or towards the distal 
end 106, will be adapted to receive a device for retaining a bearing 
pressed into the hub when a wheel assembly is mounted on the spindle. 
Typically, the adaptation to the spindle will be the placement of 
threading at the distal end to allow reception of a nut, a washer and nut 
or a combination of a washer, a nut and a locking means, such as a cotter 
pin. It is this combination which is indeed shown in FIG. 3 and designated 
as reference numeral 116. 
When the inboard and outboard bearing retainers 114, 116, respectively, are 
in place and a hub 108 with inboard and out board bearings 218, 220, 
respectively, is mounted on and secured to the spindle, the facing 
surfaces of the respective retainers 114, 116 serve to define an axial 
bearing space within which the bearings 218, 220 are constrained from 
axial movement. Additionally, a conical shim 300 is positioned concentric 
to spindle 102 between the bearings 218, 220 such that the conical shim 
and the bearings are effectively in a frictional axial fit within the 
axial bearing space. This addition complements the action of the inboard 
and outboard bearing retainers, which constrain only outward axial 
movement of the bearings by constraining axial movement of the bearings 
towards each other. 
Generally, the outboard bearing 220 will be identical to outboard bearing 
120, but the inboard bearing 218 should be carefully noted. Inboard 
bearing 218 has an annular lubrication seal 302 built into the bearing so 
that the elastomeric lip seal is frictionally fitted into the cup portion 
304 of the bearing and the lip 306 bears on the cone portion 308. Since 
the lip does this, the lubrication seal 302 is constrained within the 
axial bearing space and the spindle 102 is completely free of any contact 
with the hub or any hub components inboard of the shoulder 114, allowing 
alternate use of this region, one example of which would be placement of a 
angular velocity sensor device. As in the prior art shown in FIG. 1, 
outboard bearing 220 is smaller in both internal diameter and external 
diameter than inboard bearing 218. To accommodate the placement of the 
lubrication seal 302 into the bearing, the rollers 310 of bearing 218 will 
have a shorter length than in bearing 118. 
As in the prior art, the wheel mount 200 is provided with a distal end cap 
136, but in this case it is expected that the improved ability to seal the 
inboard end of the lubrication reservoir will permit a grease-based 
lubrication regime to be used instead of an oil-based lubrication. This 
would be expected to result in fewer failures of the wheel mount due to 
lubrication loss. 
Attention is now directed to wheel mount 250 as shown in FIG. 4. Many of 
the structures are identical to those taught in association with FIG. 2, 
and the spindle 152 and hub 158 are identical with those of FIG. 2, 
consistent with the philosophy of using the existing technology as much as 
possible. As in FIG. 3, a conical shim 350 is positioned concentric to 
spindle 152 between the bearings 268, 270 such that the conical shim and 
the bearings are effectively in a frictional axial fit within the axial 
bearing space. This addition complements the action of the inboard and 
outboard bearing retainers 164, 166, which constrain only outward axial 
movement of the bearings by constraining axial movement of the bearings 
towards each other. 
Unlike FIG. 3, FIG. 4 shows an embodiment where not only the inboard 
bearing 268 has been modified from the design of bearing 168, but the 
outboard bearing 270 has also been modified. Inboard bearing 268 has an 
annular lubrication seal 352 built into the bearing so that the 
elastomeric lip seal is frictionally fitted into the cup portion 354 of 
the bearing and the lip 356 bears on the cone portion 358. Since the lip 
does this, the lubrication seal 352 is constrained within the axial 
bearing space and the spindle 152 is completely free of any contact with 
the hub or any hub components inboard of the shoulder 164, allowing 
alternate use of this region, one example of which would be placement of a 
angular velocity sensor device. To accommodate the placement of the 
lubrication seal 352 into the bearing, the rollers 360 of bearing 268 will 
have a shorter length than in bearing 168. 
Similarly, outboard bearing 270 has an annular lubrication seal 362 built 
into the bearing so that the elastomeric lip seal is frictionally fitted 
into the cup portion 364 of the bearing and the lip 366 bears on the cone 
portion 368. Because of this, the lubrication seal 362 is constrained 
within the axial bearing space and there is no interference of the 
lubrication seal 362 with the outboard bearing retainer 156. To accomodate 
the placement of the lubrication seal 362 into the bearing, the rollers 
370 of bearing 270 will have a shorter length than in bearing 170. The use 
of this additional lubrication seal 362 would be expected to improve the 
overall sealing of the lubrication reservoir, particularly in the internal 
portion 196 of the central aperture of the wheel hub, so a grease-based 
lubrication system would be more likely to be successful than in the prior 
art. This would be expected to result in fewer failures of the wheel mount 
due to lubrication loss. 
The method for assembling the wheel mount 200 or 250 as shown in FIG. 3 or 
4 is essentially the same regardless of whether the axle is a driven or 
non-driven axle. First, an inboard bearing such as 218 or 268 is press-fit 
into an inboard bore 126 or 176 in a central aperture 122 or 172 in a hub 
108 or 158. The hub is then seated onto an axle spindle 102 or 152 such 
that the inner circumference of the inboard bearing 218 or 268 rests upon 
an inboard land 110 or 160 formed on the spindle and an inboard end of the 
inboard bearing rests against a shoulder 114 or 164 formed at an inboard 
end of the inboard land. At this point, a careful measurement of the axial 
distance from an outboard end of the inboard bearing 218 or 168 to a fixed 
point on the outboard end of the hub, which is seated upon the spindle at 
this point, is made, so that a conical shim 300 or 350 may be selected 
from a plurality of such conical shims of varying lengths. The selection 
is to be made to provide a slight interference fit in the axial direction 
of the conical shim between the cone portion of the inboard bearing and 
the cone portion of an outboard bearing 220 or 270 when the conical shim 
is placed on the spindle and the outboard bearing is press fit into an 
outboard bore 128 or 178 in the central aperture in the hub. An outboard 
bearing retainer 116 or 166 is then placed onto the distal end 106 or 156 
of the spindle to hold the outboard bearing between it and the outboard 
end of the conical shim. The outboard bearing retainer 116 or 166 should 
be tightened to a specified torque with an appropriate tool such as a 
torque wrench. The retainer should not be tightened beyond the recommended 
or specified torque. 
Although the present invention has been described above in detail, the same 
is by way of illustration and example only and is not to be taken as a 
limitation on the present invention. Accordingly, the scope and content of 
the present invention are to be defined only by the terms of the appended 
claims.