Patent Publication Number: US-2022227185-A1

Title: Wheel end assembly having an annular hub chamber

Description:
TECHNICAL FIELD 
     This document relates to a wheel end assembly that may have a wheel hub that may define an annular hub chamber. The annular hub chamber may help fluidly connect a tire inflation system to a wheel. 
     BACKGROUND 
     A tire inflation system having a passage for routing pressurized gas through a hub is disclosed in U.S. Pat. No. 9,315,077. 
     SUMMARY 
     In at least one embodiment a wheel end assembly is provided. The wheel end assembly may include a spindle, a hub, and a rotary seal assembly. The spindle may be disposed along an axis and may define a spindle air passage. The hub may be rotatable about the axis with respect to the spindle. The hub may define an annular hub chamber and at least one hub air passage. The annular hub chamber may extend around the axis. The hub air passage may have first port and a second port. The first port may be is fluidly connected to the annular hub chamber. The second port may be adapted to be fluidly connected to a wheel. The rotary seal assembly may fluidly connect the spindle air passage to a port of the annular hub chamber. 
     In at least one embodiment a wheel end assembly is provided. The wheel end assembly may include a spindle, a hub, and a rotary seal assembly. The spindle may be disposed along an axis and may define a spindle air passage. The hub may be rotatable about the axis with respect to the spindle. The hub may define an inner side, an annular hub chamber, and at least one hub air passage. The inner side may face toward the spindle. The annular hub chamber may extend around the axis and may have a port. The port may be at least partially defined by a first side wall and a second side wall that may be spaced apart from each other and that extend away from the spindle from the inner side. The hub air passage may have a first port and a second port. The first port of the hub air passage may be fluidly connected to the annular hub chamber. The second port of the hub air passage may be adapted to be fluidly connected to a wheel. The rotary seal assembly may fluidly connect the spindle air passage to the inlet of the annular hub chamber. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an example of a wheel end assembly. 
         FIG. 2  is an exploded view of a portion of the wheel end assembly. 
         FIG. 3  is a section view along section line  3 - 3  that adds at least one wheel and tire. 
         FIG. 4  is a magnified view of a portion of  FIG. 3 . 
         FIG. 5  is a section view along section line  5 - 5 . 
         FIG. 6  is an exploded view of a portion of the wheel end assembly showing a bushing that facilitates a fluid connection to a pressurized gas source. 
     
    
    
     DETAILED DESCRIPTION 
     As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention. 
     Referring to  FIG. 1 , an example of a wheel end assembly  10  is shown. The wheel end assembly  10  may be provided with a vehicle like a truck, bus, farm equipment, mining equipment, military transport or weaponry vehicle, or cargo loading equipment for land, air, or marine vessels. The vehicle may include a trailer for transporting cargo in one or more embodiments. 
     As an overview, the wheel end assembly  10  may be associated with a tire inflation system that may help obtain and/or maintain a desired air pressure within one or more tires. The tire inflation system may be disposed on the vehicle and may be configured to provide a pressurized gas or pressurized gas mixture to one or more tires and exhaust the pressurized gas or pressurized gas mixture from one or more tires. For clarity, the term “pressurized gas” may refer to either a purified pressurized gas (e.g., nitrogen) or a pressurized gas mixture (e.g., air). For convenience in reference, the term “air” is used below as a generic designator that is not intended to be limiting to a particular pressurized gas (e.g., an “air passage” may facilitate the flow of a pressurized gas other than air). Tire inflation or deflation may be desired when the tire pressure is not sufficiently close to the tire pressure specified by the vehicle manufacturer and/or is inappropriate for the type of ground over which a vehicle is travelling. For instance, higher tire pressures may be desired when a vehicle is travelling on a paved road as compared to when a vehicle is travelling off-road. 
     The tire inflation system may be fluidly connected to a pressurized gas source  12 , which is best shown in  FIG. 3 . The pressurized gas source  12  may be configured to supply or store a volume of a pressurized gas. For example, the pressurized gas source  12  may be a tank, a pump like a compressor, or combinations thereof. The pressurized gas source  12  may be configured to provide pressurized gas at a pressure that is greater than or equal to a desired inflation pressure of a tire. The pressurized gas source  12  may be disposed on the vehicle and may be fluidly connected to at least one tire via passages in various components. 
     Referring again to  FIG. 1 , the wheel end assembly  10  may be configured to support a vehicle wheel and a brake assembly. The wheel end assembly  10  may be disposed on or may be mounted to a structural component  14  and may be provided in a steerable configuration or a non-steerable configuration. In a steerable configuration, the wheel end assembly  10  may be mounted to a steerable structural component, such as a steering knuckle. In a non-steerable configuration, the wheel end assembly  10  may be mounted to a non-steerable structural component, such as a non-rotatable knuckle or an axle housing of an axle assembly. In at least one configuration and as is best shown with reference to  FIGS. 2 and 3 , the wheel end assembly  10  may include a spindle  20 , a hub  22 , an inboard wheel bearing  24 , an outboard wheel bearing  26 , a hub seal  28 , and a rotary seal assembly  30 . Optionally, the wheel end assembly  10  may be associated with an axle shaft  32  and may include hub housing  34 , a brake drum  36 , and a gear reduction unit  38 , which is best shown in  FIG. 3 . 
     Referring to  FIGS. 2 and 3 , the spindle  20  may extend along or around an axis  40  and may be configured to support components of the wheel end assembly  10 . The spindle  20  may be fixedly mounted to a structural component  14 , such as a steering knuckle or an axle housing as previously described. It is also contemplated that the spindle  20  may be integrally formed with the structural component  14  rather than being a separate part from the structural component  14 . In at least one configuration, the spindle  20  may include a mounting flange  50  and a tubular portion  52 . In addition, the spindle  20  may define a spindle air passage  54  and optionally a spindle hole  56 . 
     The mounting flange  50  may facilitate mounting of the spindle  20  to a structural component  14 . For instance, the structural component  14  may include a mounting ring  60  that may be integrally formed with the structural component  14  or may be provided as a separate part that is fixedly attached to structural component  14 . The mounting ring  60  may extend around the axis  40 , may be received inside a hole in the structural component  14 , and/or may have holes that facilitate mounting of the spindle  20 . As is best shown with in  FIGS. 2 and 6 , the mounting flange  50  may have an air passage hole  62 . 
     Referring to  FIG. 6 , the air passage hole  62  may be a through hole that may extend through the mounting ring  60 . The air passage hole  62  may have a recess  64 . The recess  64  may have any suitable shape. For instance, the recess  64  may be generally D-shaped and may include a straight side  66  and a curved side  68  that extends along an arc or radius from one end of the straight side  66  to an opposite end of the straight side  66 . 
     A hollow tubular bushing  70  may extend through the air passage hole  62  and may facilitate mounting of a fitting  72  that may be fluidly connectable to the pressurized gas source  12 . The bushing  70  may have a shape that is compatible with the air passage hole  62 . For instance, the bushing  70  may have a bushing flange  74  that may be received in the recess  64  to help inhibit rotation of the bushing  70  with respect to the mounting ring  60 . In the configuration shown, the bushing flange  74  may have a D-shaped perimeter that may have a straight bushing flange side  76  and a curved bushing flange side  78  that extends along an arc or radius from one end of the straight bushing flange side  76  to an opposite end of the straight bushing flange side  76 . The straight bushing flange side  76  and a curved bushing flange side  78  may be aligned with the straight side  66  and a curved side  68 , respectively. It is also contemplated that the bushing  70  may be omitted and that the fitting  72  may be directed coupled to the mounting ring  60 . 
     Referring to  FIGS. 2 and 4 , the mounting flange  50  may be disposed at an inboard end of the spindle  20  that may be disposed adjacent to the structural component  14 . In at least one configuration, the mounting flange  50  may extend further away from the axis  40  than the tubular portion  52  and may extend radially outward from the tubular portion  52 . The mounting flange  50  may include a plurality of holes  80  that may receive fasteners  82 , such as bolts, that may couple the spindle  20  to the structural component  14 , such as to the mounting ring  60 . Alternatively, the holes  80  and fasteners  82  may be omitted and the spindle  20  may be coupled to the structural component  14  with a weld, by press fitting, or the like. The mounting flange  50  may be disposed at an end of the tubular portion  52 . 
     Referring primarily to  FIG. 2 , the tubular portion  52  may extend from the mounting flange  50 . For instance, the tubular portion  52  may extend in an axial direction that may extend away from the mounting flange  50  in an outboard direction away from the structural component  14 . In at least one configuration, the tubular portion  52  may have a threaded portion  90 . The tubular portion  52  may include one or more outer surfaces, such as a first outer surface  92 , a second outer surface  94 , a third outer surface  96 , and a fourth outer surface  98 . 
     The threaded portion  90  may be axially positioned or positioned along the axis  40  between the distal end of the spindle  20  and the first outer surface  92 . The threaded portion  90  may face away from the axis  40  and may threadingly engage a preload nut  100 . For instance, the preload nut  100  may be threaded onto the threaded portion  90 , may inhibit axial movement of the outboard wheel bearing  26 , and may exert a preload force on the outboard wheel bearing  26 . 
     The first outer surface  92  may extend around the axis  40  and may face away from the axis  40 . The first outer surface  92  may be an outside circumference of a portion of the tubular portion  52 . The first outer surface  92  may be axially positioned between the threaded portion  90  and the second outer surface  94 . In addition, the first outer surface  92  may be positioned further from the axis  40  than the threaded portion  90 . The outboard wheel bearing  26  may be disposed on the first outer surface  92 . 
     The second outer surface  94  may extend around the axis  40  and may face away from the axis  40 . The second outer surface  94  may be an outside circumference of a portion of the tubular portion  52 . The second outer surface  94  may be axially positioned between the first outer surface  92  and the mounting flange  50 . For instance, the second outer surface  94  may be axially positioned between the first outer surface  92  and the third outer surface  96 . In addition, the second outer surface  94  may be disposed further from the axis  40  than the first outer surface  92  and may have a larger diameter than the first outer surface  92  to help inhibit axial movement of the inner race of the outboard wheel bearing  26  toward the mounting flange  50 . The rotary seal assembly  30  may be disposed on the second outer surface  94 . It is also contemplated that the second outer surface  94  may be omitted and the outboard wheel bearing  26  and the rotary seal assembly  30  may be disposed on a common surface, such as the first outer surface  92 . 
     The third outer surface  96  may extend around the axis  40  and may face away from the axis  40 . The third outer surface  96  may be an outside circumference of a portion of the tubular portion  52 . The third outer surface  96  may be axially positioned between the second outer surface  94  and the mounting flange  50 . For instance, the third outer surface  96  may be axially positioned between the second outer surface  94  and the fourth outer surface  98 . In addition, the third outer surface  96  may be disposed further from the axis  40  than the second outer surface  94  and may have a larger diameter than the second outer surface  94 . It is also contemplated that the third outer surface  96  may be omitted and the rotary seal assembly  30  may be disposed on a common surface, such as the first outer surface  92  or the second outer surface  94 . The inboard wheel bearing  24  may be disposed on the third outer surface  96 . 
     The fourth outer surface  98  may extend around the axis  40  and may face away from the axis  40 . The fourth outer surface  98  may be an outside circumference of a portion of the tubular portion  52 . The fourth outer surface  98  may be axially positioned between the third outer surface  96  and the mounting flange  50 . In at least one configuration, the fourth outer surface  98  may extend from the mounting flange  50 . The fourth outer surface  98  may be disposed further from the axis  40  than the third outer surface  96  and may have a larger diameter than the third outer surface  96  to help inhibit axial movement of the inner race of the inboard wheel bearing  24  toward the mounting flange  50 . The hub seal  28  may be disposed on the fourth outer surface  98 . It is contemplated that the fourth outer surface  98  may be omitted and that the hub seal  28  and the inboard wheel bearing  24  may be disposed on a common surface. 
     Referring to  FIG. 3 , the spindle air passage  54  may help fluidly connect a pressurized gas source  12  to a tire  110  that may be mounted on a wheel  112 . The spindle air passage  54  may be spaced apart from the spindle hole  56 . In at least one configuration, the spindle air passage  54  may extend through the mounting flange  50  and the tubular portion  52  of the spindle  20 . As is best shown in  FIG. 4 , the spindle air passage  54  may have a first port  120  and a second port  122 . 
     The first port  120  may be fluidly connectable to the pressurized gas source  12 . In at least one configuration, the first port  120  may be provided in the mounting flange  50 . 
     The second port  122  may be disposed at an opposite end of the spindle air passage  54  from the first port  120 . The second port  122  may be fluidly connected to an air passage in the hub  22  via the rotary seal assembly  30 . The second port  122  may be provided in the tubular portion  52 . For instance, the second port  122  may extend from an outer surface of the spindle  20 , such as the second outer surface  94 . 
     The mounting flange  50  and the tubular portion  52  may cooperate to define the spindle hole  56 . The spindle hole  56  may be a through hole that may extend along and may be centered about the axis  40 . 
     Referring to  FIGS. 2 and 4 , the hub  22  may be rotatable about the axis  40  with respect to the spindle  20 . In addition, the hub  22  may be configured to facilitate mounting of at least one wheel  112 . In a drive axle configuration, the hub  22  may be operatively connected to an axle shaft  32 . In at least one configuration, the hub  22  may include a hub cavity  130 , a hub mounting flange  132 , an annular hub chamber  134 , and at least one hub air passage  136 . 
     The hub cavity  130  may extend around the axis  40 . The hub cavity  130  may receive at least a portion of various components of the wheel end assembly  10 , such as the spindle  20 , the inboard wheel bearing  24 , the outboard wheel bearing  26 , the hub seal  28 , the rotary seal assembly  30 , and the gear reduction unit  38 . The hub cavity  130  may be at least partially defined by an inner side  140  that may face toward the spindle  20  and that may extend around the axis  40 . 
     The hub mounting flange  132  may facilitate mounting of at least one wheel  112 . For example, the hub mounting flange  132  may extend away from the axis  40  and may include a set of mounting fastener holes that may each receive a mounting lug bolt  150 . A mounting lug bolt  150  may extend through a corresponding hole in a wheel  112 . A lug nut  152  may be threaded onto a mounting lug bolt  150  to secure a wheel  112  to the hub  22 . In the configuration shown in  FIGS. 3 and 4 , two wheels  112  are illustrated that each support a corresponding tire  110 ; however, it is contemplated that a single wheel  112  and tire  110  may be provided. 
     Referring primarily to  FIGS. 4 and 5 , the annular hub chamber  134  may fluidly connect the spindle air passage  54  to at least one hub air passage  136 . The annular hub chamber  134  may extend around the axis  40 . The annular hub chamber  134  may have a port  160  and may be at least partially defined by an arcuate wall  162 . Optionally, the annular hub chamber  134  may be further defined by a first connecting wall  164 , a second connecting wall  166 , or both. 
     Referring to  FIG. 4 , the port  160  may be fluidly connected to the second port  122  of the spindle air passage  54 . For instance, the port  160  may be disposed proximate the rotary seal assembly  30 . The port  160  may extend continuously around the axis  40 . The port  160  may or may not extend from the arcuate wall  162 . In at least one configuration, the port  160  may be at least partially defined by a first side wall  170  and a second side wall  172 . 
     The first side wall  170  and the second side wall  172  may be spaced apart from each other. The first side wall  170  and the second side wall  172  may extend from the inner side  140  of the hub  22  in a direction that extends away from the spindle  20 . In at least one configuration, first side wall  170  and the second side wall  172  may be disposed substantially perpendicular to the axis  40 . Substantially perpendicular may be within ±2° of perpendicular. 
     Referring to  FIG. 4 , the arcuate wall  162  may face toward the axis  40  and may extend along an arc. At least a portion of the arcuate wall  162  may be disposed further from the axis  40  than the inboard wheel bearing  24 , the outboard wheel bearing  26 , or both. 
     Optionally, a first connecting wall  164  and a second connecting wall  166  may help define the annular hub chamber  134 . The first connecting wall  164  may extend from an end of the first side wall  170  to a first end of the arcuate wall  162 . The second connecting wall  166  may extend from an end of the second side wall  172  to a second end of the arcuate wall  162  that may be disposed opposite the first end of the arcuate wall  162 . It is also contemplated that the first connecting wall  164 , the second connecting wall  166 , or both may be omitted. For instance, a first end of the arcuate wall  162  may extend from an end of the first side wall  170  when the first connecting wall  164  is omitted. Similarly the second end of the arcuate wall  162  may extend from an end of the second side wall  172  when the second connecting wall  166  is omitted. 
     At least one hub air passage  136  may be provided with the hub  22 . A hub air passage  136  may fluidly connect the annular hub chamber  134  to a tire  110 . The hub air passage  136  may be defined in the hub  22  and may extend through the hub  22 . In  FIG. 3 , two hub air passages  136  are illustrated. For convenience in reference, the hub air passages  136  may be referred to as a first hub air passage and a second hub air passage. The first hub air passage and the second hub air passage may be disposed on opposite sides of the spindle  20 . The first and second hub air passages may be fluidly connected to a common tire  110  and wheel  112  or may be fluidly connected to different tires  110  and wheels  112  as will be discussed in more detail below. In at least one configuration, the first hub air passage may be disposed directly opposite the second hub air passage such that the first hub air passage and the second hub air passage may be coplanar. As is best shown in  FIG. 4 , the hub air passage  136  may have a first port  180  and a second port  182 . The hub air passage  136  may also have a first segment  184 , a second segment  186 , and a third segment  188 . 
     The first port  180  may be fluidly connected to the annular hub chamber  134 . For instance, the first port  180  may extend from the arcuate wall  162 . The first port  180  may be axially positioned further from the distal end of the spindle  20  than the port  160  of the annular hub chamber  134  is positioned from the distal end of the spindle  20 . 
     The second port  182  may be disposed at an opposite end of the hub air passage  136  from the first port  180 . The second port  182  may be fluidly connectable to a wheel  112 , such as via a conduit as will be discussed in more detail below. 
     The first segment  184  may extend from the annular hub chamber  134 . For instance, the first segment  184  may include the first port  180  and may extend from the annular hub chamber  134  at an oblique angle with respect to the axis  40 . 
     The second segment  186  may fluidly connect the first segment  184  to the third segment  188 . For instance, the second segment  186  may extend from the first segment  184  in a direction that extends away from the axis  40 . In at least one configuration, the second segment  186  may be disposed substantially perpendicular to the axis  40 . Substantially perpendicular may be within ±2° of perpendicular. 
     The third segment  188  may extend from the second segment  186  to the second port  182 . In at least one configuration, the third segment  188  may extend substantially parallel to the axis  40 . Substantially perpendicular may be within ±2° of parallel. 
     Referring to  FIGS. 2 and 4 , the inboard wheel bearing  24  may be disposed on the spindle  20  and may rotatably support the hub  22 . The inboard wheel bearing  24  may have any suitable configuration. For instance, the inboard wheel bearing  24  may include a plurality of rolling elements, such as balls or rollers, that may be disposed between an inner race and an outer race. The inner race may extend around and may be disposed on a surface of the spindle  20 , such as the third outer surface  96 . As such, the inboard wheel bearing  24  may be axially positioned closer to the mounting flange  50  than the outboard wheel bearing  26 . The outer race may engage the hub  22  and may extend around the inner race. 
     The outboard wheel bearing  26  may be disposed on the spindle  20  and may rotatably support the hub  22 . The outboard wheel bearing  26  may have a similar configuration as the inboard wheel bearing  24 . For instance, the outboard wheel bearing  26  may include a plurality of rolling elements, such as balls or rollers, that may be disposed between an inner race and an outer race. The inner race may extend around and may be disposed on a surface of the spindle  20 , such as the first outer surface  92 . The outer race may engage the hub  22  and may extend around the inner race. 
     The hub seal  28  may extend from the spindle  20  to the hub  22 . For example, the hub seal  28  may extend from the fourth outer surface  98  of the spindle  20  in a direction that extends away from the axis  40  to the hub  22 . The hub seal  28  may be disposed near an inboard end of the hub  22  that may be disposed closest to the mounting flange  50  of the spindle  20 . The hub seal  28  may be axially positioned between the inboard wheel bearing  24  and the mounting flange  50 . 
     The rotary seal assembly  30  may fluidly connect the spindle air passage  54  to the hub air passage  136 . More specifically, the rotary seal assembly  30  may fluidly connect the second port  122  of the spindle air passage  54  to the port  160  of the hub air passage  136 . The rotary seal assembly  30  may extend from the spindle  20  to the hub  22 . For example, the rotary seal assembly  30  may extend from the second outer surface  94  of the spindle  20  in a direction that extends away from the axis  40  to the hub  22 . The rotary seal assembly  30  may be axially positioned between the inboard wheel bearing  24  and the outboard wheel bearing  26 . The rotary seal assembly  30  may seal against the spindle  20  and the hub  22  in a manner that permits the hub  22  to rotate with respect to the spindle  20 . As one example, the rotary seal assembly  30  may be fixedly disposed on the spindle  20  such that the rotary seal assembly  30  does not rotate with respect to the spindle  20  and the hub  22  may rotate with respect to the rotary seal assembly  30 . As another example, the rotary seal assembly  30  may be fixedly disposed on the hub  22  such that the hub  22  and the rotary seal assembly  30  may be rotatable with respect to the spindle  20 . 
     The rotary seal assembly  30  may have any suitable configuration. For instance, the rotary seal assembly  30  may extend continuously around the spindle  20  and may have an inboard sealing portion  200  and an outboard sealing portion  202 . The inboard sealing portion  200  may extend from the spindle  20  to the hub  22  and may be axially positioned between the inboard wheel bearing  24  and the second port  122  of the spindle air passage  54 . The outboard sealing portion  202  may extend from the spindle  20  to the hub  22  and may be axially positioned between the outboard wheel bearing  26  and the second port  122  of the spindle air passage  54 . As such, the spindle  20 , the hub  22 , the inboard sealing portion  200 , and the outboard sealing portion  202  may cooperate to define a chamber from which the second port  122  of the spindle air passage  54  and the port  160  of the annular hub chamber  134  may extend. 
     Referring to  FIGS. 1 and 2 , the hub housing  34  may be mounted to the hub  22 . For example, the hub housing  34  may be attached to an end of the hub  22  that faces away from the mounting flange  50  of the spindle  20 . The hub housing  34  may enclose an outboard end of the hub cavity  130 . 
     Referring to  FIGS. 2 and 3 , the axle shaft  32 , if provided, may provide torque to the wheel end assembly  10 . For instance, the axle shaft  32  may be operatively connected at a first end to a vehicle drivetrain component, such as a differential or vehicle power source, and may be coupled to or operatively connected to the wheel end assembly  10  at a second end. In at least one embodiment, the axle shaft  32  or a portion thereof may extend along the axis  40 . For example, the axle shaft  32  or a portion thereof may extend through the spindle hole  56  and may be operatively connected to the hub  22 , such as via the gear reduction unit  38  or without the gear reduction unit  38 . It is also contemplated that the axle shaft  32  may be configured for use with an independent suspension system and may have multiple shaft segments and/or joints that may facilitate relative movement between the first end and the wheel end assembly  10 . 
     The hub housing  34 , if provided, may be fixedly mounted to the hub  22 . As such, the hub housing  34  and the hub  22  may be rotatable together about the axis  40  with respect to the spindle  20 . The hub housing  34  may extend around and may at least partially receive the spindle  20 , the hub  22 , the outboard wheel bearing  26 , the rotary seal assembly  30 , the annular hub chamber  134 , or combinations thereof. The hub housing  34  may also receive the gear reduction unit  38 . In at least one configuration and as is best shown with reference to  FIG. 4 , the hub housing  34  may include a hub housing flange  210  and at least one hub housing passage  212 . 
     The hub housing flange  210  may be disposed at an end of the hub housing  34  that may face toward the hub mounting flange  132 . The hub housing flange  210  may extend away from the axis  40  and may have a first flange side  220  and a second flange side  222 . 
     The first flange side  220  may face toward the hub mounting flange  132 . For example, the first flange side  220  may engage or contact the hub mounting flange  132 . 
     The second flange side  222  may be disposed opposite the first flange side  220 . The second flange side  222  may face toward and may engage or contact the brake drum  36 . 
     The hub housing passage  212  may be configured as a through hole that may extend from the first flange side  220  to the second flange side  222 . A different hub housing passage  212  may be associated with each hub air passage  136 . For instance, a hub housing passage  212  may be aligned with and may be fluidly connected to a corresponding hub air passage  136 . 
     Referring to  FIGS. 1 and 2 , the brake drum  36  may be fixedly mounted to the hub  22 . As such, the brake drum  36  and the hub  22  may be rotatable together about the axis  40  with respect to the spindle  20 . The brake drum  36  may extend around and may at least partially receive the spindle  20 , the hub  22 , the inboard wheel bearing  24 , the rotary seal assembly  30 , the annular hub chamber  134 , or combinations thereof. The brake drum  36  may also receive one or more brake pad assemblies in a manner known by those skilled in the art. In at least one configuration and as is best shown with reference to  FIG. 4 , the brake drum  36  may include a brake drum flange  230  and at least one brake drum passage  232 . 
     The brake drum flange  230  may be disposed at an end of the brake drum  36  that may face toward the hub mounting flange  132 . The brake drum flange  230  may extend toward the axis  40  and may have a first brake drum flange side  240  and a second brake drum flange side  242 . 
     The first brake drum flange side  240  may face toward the hub mounting flange  132 . For example, the first brake drum flange side  240  may engage or contact the hub housing flange  210  or may engage or contact the hub mounting flange  132  if a hub housing  34  is not axially positioned between the hub  22  and the brake drum  36 . 
     The second brake drum flange side  242  may be disposed opposite the first brake drum flange side  240 . The second brake drum flange side  242  may face toward and may engage or contact a wheel  112 . 
     The brake drum passage  232  to may be configured as a through hole that may extend from the first brake drum flange side  240  to the second brake drum flange side  242 . The brake drum passage  232  may be aligned with and may be fluidly connected to a corresponding hub air passage  136 . For instance, a brake drum passage  232  may be disposed adjacent to and may be fluidly connected to a hub housing passage  212  and the hub housing passage  212  may be disposed adjacent to and may be fluidly connected to the hub air passage  136 . It is also contemplated that the axial positioning of the hub housing  34  and the brake drum  36  may be reversed, in which case the brake drum flange  230  may be disposed between the hub housing flange  210  and the hub mounting flange  132 . It is also contemplated that the hub housing  34  may be omitted and that the brake drum  36  may be disposed adjacent to the hub mounting flange  132 . 
     One or more seals may be provided to inhibit leakage of pressurized gas. For instance, a first seal  250  may be disposed between and may contact or engage the hub mounting flange  132  and the hub housing flange  210  while a second seal may be disposed between and may contact or engage the hub housing flange  210  and the brake drum flange  230 . For instance, the first seal  250  may contact or engage the first flange side  220  and may extend around the hub housing passage  212  while the second seal  252  may contact or engage the second flange side  222  and may extend around the hub housing passage  212 . The seal may have any suitable configuration. For instance, a seal may be configured as an O-ring, gasket, or the like. 
     Referring to  FIG. 3 , a conduit  260  may fluidly connect a hub air passage  136  to a wheel  112 . In the configuration shown, two conduits  260  are depicted. Each conduit  260  may be fluidly connected to the same tire  110  and wheel  112  or may be fluidly connected to different tires  110  and wheels  112 . For instance, one conduit  260  may fluidly connect one hub air passage  136  to a first wheel  112  while a second conduit  260  fluidly connects the other hub air passage  136  to a second wheel  112 . As such, multiple tires may be inflated or deflated via the conduits  260 . Alternatively, a single tire  110  and wheel  112  may be mounted on the hub  22  and both conduits  260  may be fluidly connected to the same wheel  112 , such as via two separate fittings or tire valves that may be provided with the wheel  112 . As such, the volume of air that may be provided to a tire  110  or removed from a tire  110  and/or the air flow rate may be increased, which may help reduce tire inflation and/or deflation times. 
     In at least one configuration, each conduit  260  may extend through a different opening in a wheel  112 . A conduit  260  may extend from the brake drum  36  and may be fluidly connected to the brake drum passage  232 ; however it is also contemplated that the conduit  260  may extend from the hub housing  34  and an associated hub housing passage  212  or a conduit  260  may extend from the hub mounting flange  132  and an associated hub air passage  136 . 
     The gear reduction unit  38 , if provided, may operatively connect the axle shaft  32  to the hub  22 . The gear reduction unit  38  may be at least partially disposed in the hub  22  and may transmit torque from the axle shaft  32  to the hub  22 . The gear reduction unit  38  may have any suitable configuration. For instance, the gear reduction unit  38  may be configured as a planetary gear set. The gear reduction unit  38  may be disposed proximate the distal end of the spindle  20  and may be received in the hub housing  34 . 
     A wheel end assembly as described above may allow a tire inflation system to route pressurized gas through a spindle and a hub rather than through external tubing or hoses that may be received inside the spindle hole or that may extend along an exterior surface of a hub, which may help reduce package space and avoid damage to which external tubing is susceptible. Routing pressurized gas through passages in a brake drum and/or hub housing may help further internalize the flow path for pressurized gas. Providing internal flow passages for pressurized gas may also help reduce potential leak paths and connection points. Providing an internal annular hub chamber may permit pressurized gas to be provided to multiple hub passages, which in turn may allow multiple tires to be inflated or may facilitate multiple fluid connections to a single tire, which may allow a greater volume of air to be provided to or exhausted from a tire and/or may decrease tire inflation and deflation times, thereby improving performance. 
     While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.