Patent Description:
An axle assembly having an upper lubricant reservoir disposed inside a differential carrier is disclosed in <CIT>. <CIT> discloses an axle assembly that has a lubricant reservoir that is defined by an upper side of a leg that extends from a differential carrier to a bearing cap.

The latter discloses, in the opinion of the Examining Division of the European Patent Office, an axle assembly comprising: a differential assembly that is rotatable about an axis and that has a ring gear; a housing assembly that receives the differential assembly; a lubricant reservoir that is disposed above the differential assembly and that captures lubricant that is splashed by the ring gear.

According to claim <NUM>, an axle assembly is provided comprising: a differential assembly that is rotatable about an axis and that has a ring gear; a housing assembly that receives the differential assembly; a lubricant reservoir that is disposed above the differential assembly and that captures lubricant that is splashed by the ring gear; and a lubricant distribution trough that receives lubricant from the lubricant reservoir. The lubricant distribution trough includes: a first trough that receives lubricant from the lubricant reservoir; a second trough that is disposed below the first trough; and a dam that separates the first trough from the second trough.

The first trough may provide lubricant to an input shaft bearing that rotatably supports an input shaft. The second trough may provide lubricant to an interaxle differential unit. The second trough may provide lubricant to a drop gear set that is operatively connected to the input shaft. The second trough may provide lubricant to a drive pinion that meshes with the ring gear of the differential assembly.

The second trough may receive lubricant that is splashed by the differential assembly.

The second trough may be divided into an upper portion and a lower portion. The upper portion may extend from the dam to the lower portion. The upper portion may be elevated with respect to the lower portion. The upper portion may provide lubricant to an interaxle differential unit. The upper portion may provide lubricant to a drop gear set. The lower portion may receive lubricant that is splashed by the differential assembly.

The axle assembly <NUM> may be provided with a vehicle of any suitable type, such as a truck, bus, farm equipment, mining equipment, military transport or weaponry vehicle, or cargo loading equipment for land, air, or marine vessels.

The axle assembly <NUM> may be part of a vehicle drivetrain that may provide torque to one or more traction wheel assemblies that may include a tire mounted on a wheel. One or more axle assemblies <NUM> may be provided with the vehicle. For example, the axle assembly <NUM> may be a single drive axle assembly or may be configured as part of a tandem axle configuration or multi-axle configuration that may include a plurality of axle assemblies connected in series. The axle assembly <NUM> that is operatively connected to at least one torque source, such as an electric motor or an internal combustion engine, may be referred to as a first axle assembly. The axle assembly that receives propulsion torque from the torque source by way of the first axle assembly may be referred to as a second axle assembly. In <FIG>, the axle assembly <NUM> is depicted as being a first axle assembly.

The axle assembly <NUM> may provide torque to its associated wheel assemblies and may provide torque to the second axle assembly. In at least one embodiment and as is best shown with reference to <FIG> and <FIG>, the axle assembly <NUM> includes a housing assembly <NUM> and a differential assembly <NUM> and may include an input yoke <NUM>, an input shaft <NUM>, a drop gear set <NUM>, a clutch collar <NUM>, a drive pinion <NUM>, at least one axle shaft <NUM>, an interaxle differential unit <NUM>, an output shaft <NUM>, an output yoke <NUM>, or combinations thereof. These components are shown to facilitate an abbreviated discussion of the operation of the axle assembly <NUM>. The axle assembly <NUM> may also include a lubricant reservoir <NUM>, a first conduit <NUM>, and a second conduit <NUM>.

The axle housing <NUM> may receive and support the axle shafts <NUM>. In at least one configuration, the axle housing <NUM> may include a center portion <NUM> and at least one arm portion <NUM>.

The center portion <NUM> may be disposed proximate the center of the axle housing <NUM>. As is best shown in <FIG>, the center portion <NUM> may define an internal cavity that may at least partially receive the differential assembly <NUM>. The internal cavity may also receive the lubricant reservoir <NUM>. A lower region of the center portion <NUM> may at least partially define a sump portion <NUM> that may contain or collect lubricant <NUM>. Lubricant <NUM> in the sump portion <NUM> may be splashed by the differential assembly <NUM> when the differential assembly <NUM> rotates. Some splashed lubricant <NUM> may be captured or collected by the lubricant reservoir <NUM> as will be discussed in more detail below. The center portion <NUM> may also include a bowl cover <NUM> that may be disposed opposite the differential carrier <NUM>. In at least one configuration, the bowl cover <NUM> may be configured as a spherical cap or dome and may enclose a side of the center portion <NUM> that is disposed opposite the differential carrier <NUM>.

The lubricant <NUM>, which may be a liquid such as oil, may lubricate components of the axle assembly <NUM>, such as the differential assembly <NUM> and various bearings. In <FIG>, the level of the lubricant <NUM> in the sump portion <NUM> is represented by the dashed lines. The lubricant level is merely an example and may be higher or lower than what is depicted.

Referring to <FIG>, one or more arm portions <NUM> may extend from the center portion <NUM>. For example, two arm portions <NUM> may extend in opposite directions from the center portion <NUM> and away from the differential assembly <NUM>. The arm portions <NUM> may have similar configurations. For example, the arm portions <NUM> may each have a hollow configuration or tubular configuration that may extend around a corresponding axle shaft <NUM> and may help separate or isolate the axle shaft <NUM> from the surrounding environment. An arm portion <NUM> or a portion thereof may be integrally formed with the center portion <NUM>. Alternatively, an arm portion <NUM> may be separate from the center portion <NUM>. In such a configuration, each arm portion <NUM> may be attached to the center portion <NUM> in any suitable manner, such as by welding or with one or more fasteners. Each arm portion <NUM> may define an arm cavity that may receive a corresponding axle shaft <NUM>. The arm portion <NUM> and arm cavity may be disposed above the sump portion <NUM>.

Referring primarily to <FIG>, the differential carrier <NUM> may be mounted to the center portion <NUM> of the axle housing <NUM>. The differential carrier <NUM> may support the differential assembly <NUM>. In at least one configuration, the differential carrier <NUM> may include a flange portion <NUM>. The differential carrier <NUM> may also include at least one differential bearing support <NUM> as is best shown in <FIG>.

Referring to <FIG>, the flange portion <NUM> may facilitate mounting of the differential carrier <NUM> to another component of the axle assembly <NUM>, such as the axle housing <NUM>. For example, the flange portion <NUM> may be disposed proximate and may engage the center portion <NUM> of the axle housing <NUM> and may have a set of holes that may receive fasteners, such as bolts, that may couple the differential carrier <NUM> to the axle housing <NUM>.

Referring to <FIG>, the differential bearing support <NUM> may receive a bearing <NUM> that may rotatably support the differential assembly <NUM>. In <FIG>, a bearing cap that may arch over the bearing <NUM> is omitted for clarity. The bearing <NUM> may have any suitable configuration. For instance, the bearing <NUM> may be a roller bearing assembly. In the configuration shown, two differential bearing supports <NUM> are provided with the differential carrier <NUM>. The differential bearing supports <NUM> may be received inside the center portion <NUM> of the axle housing <NUM> and may be disposed proximate opposite ends of the differential assembly <NUM>.

Referring to <FIG> and <FIG>, the input yoke <NUM> may facilitate coupling of the axle assembly <NUM> to a torque source. The input yoke <NUM> may be operatively connected to the input shaft <NUM>. As is best shown in <FIG>, an input seal <NUM> may be disposed adjacent to the input yoke <NUM>. The input seal <NUM> may be at least partially received inside a hole in the differential carrier <NUM> and may encircle the input yoke <NUM>. It is contemplated that the input yoke <NUM> and the input seal <NUM> may be omitted, such as when a torque source like an electric motor is integrated with the axle assembly <NUM>.

Referring to <FIG>, an example of an input shaft <NUM> is shown. The input shaft <NUM> may extend along and may be rotatable about a first axis <NUM>. For example, the input shaft <NUM> may be rotatably supported by one or more bearings that may be disposed on the housing assembly <NUM>, such as an input shaft bearing <NUM>. The input shaft bearing <NUM> may be mounted to the differential carrier <NUM> and may encircle the input shaft <NUM>. In addition, the input shaft bearing <NUM> may be disposed proximate the input seal <NUM>. The input shaft <NUM> may be operatively connected to the interaxle differential unit <NUM>.

The drop gear set <NUM> may be operatively connected to the input shaft <NUM> and to the drive pinion <NUM>. The drop gear set <NUM> may include a first gear <NUM> and a second gear <NUM>.

The first gear <NUM>, which may also be referred to as a drive gear, may be rotatably disposed on the input shaft <NUM>. In addition, the first gear <NUM> may be selectively coupled to the input shaft <NUM> with the clutch collar <NUM>. For instance, the first gear <NUM> may be rotatable about the first axis <NUM> with the input shaft <NUM> when the clutch collar <NUM> couples the first gear <NUM> to the input shaft <NUM> and the first gear <NUM> may be rotatable about the first axis <NUM> with respect to the input shaft <NUM> when the clutch collar <NUM> does not couple the first gear <NUM> to the input shaft <NUM>. In at least one configuration, the first gear <NUM> may have a center bore that may receive the input shaft <NUM> and optionally a bearing that may rotatably support the first gear <NUM> on the input shaft <NUM>. In at least one configuration, the first gear <NUM> may include outer gear teeth <NUM>, face gear teeth <NUM>, and side gear teeth <NUM>.

The outer gear teeth <NUM> may engage and may mesh with teeth on the second gear <NUM>. The outer gear teeth <NUM> may extend away from the first axis <NUM> and may be arranged around an outside diameter of the first gear <NUM>.

The face gear teeth <NUM> may include a set of teeth that may be arranged on a side or face of the first gear <NUM> that may face away from the interaxle differential unit <NUM> and toward the clutch collar <NUM>. The face gear teeth <NUM> may selectively engage teeth on the clutch collar <NUM>, such as when the clutch collar <NUM> couples the first gear <NUM> to the input shaft <NUM>.

The side gear teeth <NUM> may be disposed on an opposite side of the first gear <NUM> from the face gear teeth <NUM>. The side gear teeth <NUM> may be arranged around the first axis <NUM> and that may face toward and may mesh with one or more pinion gears <NUM> that may be disposed inside the interaxle differential unit <NUM>.

The second gear <NUM>, which may also be referred to as a driven gear, may be rotatable about a second axis <NUM>. For example, the drive pinion <NUM> may be received in a center bore of the second gear <NUM> and the second gear <NUM> may be fixedly disposed on the drive pinion <NUM> or may be couplable to the drive pinion <NUM> such that the second gear <NUM> and the drive pinion <NUM> may rotate together about the second axis <NUM>. The second gear <NUM> may include a plurality of teeth that may be generally arranged about an outside diameter of the second gear <NUM> and that may mate or mesh with the teeth of the outer gear teeth <NUM> of the first gear <NUM>. The second axis <NUM> may be disposed substantially parallel to the first axis <NUM>. The term "substantially parallel" as used herein means the same as or very close to parallel and includes features or axes that are within ±<NUM>° of being parallel each other.

Referring to <FIG>, the clutch collar <NUM>, if provided, may be moveable along the first axis <NUM> to engage or disengage the first gear <NUM>. For instance, the clutch collar <NUM> may have a spline that may mate with a corresponding spline of the input shaft <NUM> such that the clutch collar <NUM> is rotatable about the first axis <NUM> with the input shaft <NUM> and may be movable along the first axis <NUM> with respect to the input shaft <NUM>. The clutch collar <NUM> may have a clutch collar face gear that may be selectively engageable with the face gear teeth <NUM> of the first gear <NUM>.

The drive pinion <NUM> may operatively connect the torque source to the differential assembly <NUM>. The drive pinion <NUM> may be spaced apart from the input shaft <NUM> and may be configured to rotate about an axis, such as a second axis <NUM>. The drive pinion <NUM> may rotate with the second gear <NUM>. It is also contemplated that the drive pinion <NUM> may rotate about the first axis <NUM> in other configurations, such as when the first gear <NUM> and the second gear <NUM> are omitted or when the output shaft <NUM> extends through the drive pinion <NUM>. A gear portion may be disposed at an end of the drive pinion <NUM>.

Referring to <FIG> and <FIG>, the differential assembly <NUM> is received in the housing assembly <NUM>. For instance, the differential assembly <NUM> may be at least partially received inside the axle housing <NUM>. The differential assembly <NUM> is rotatable about an axis, such as a differential axis <NUM>. In at least one configuration, the differential axis <NUM> may be disposed substantially perpendicular to the second axis <NUM>. The term "substantially perpendicular" is used herein to designate features or axes that are the same as or very close to perpendicular and includes features that are within ±<NUM>° of being perpendicular each other. The differential assembly <NUM> may transmit torque to the axle shafts <NUM> and wheels. For example, the differential assembly <NUM> may be operatively connected to the axle shafts <NUM> and may permit the axle shafts <NUM> to rotate at different rotational speeds in a manner known by those skilled in the art. The differential assembly <NUM> has a ring gear <NUM> that may have teeth that may mate or mesh with the teeth of the gear portion of the drive pinion <NUM>. Accordingly, the differential assembly <NUM> may receive torque from the drive pinion <NUM> via the ring gear <NUM> and transmit torque to the axle shafts <NUM>. For instance, the ring gear <NUM> may be fixedly mounted to a case of the differential assembly <NUM>. The case may receive gears that may be operatively connected to the axle shafts <NUM>. The ring gear <NUM> may be rotatable about that differential axis <NUM> with the case and may splash lubricant <NUM> that has accumulated in the sump portion <NUM> as it rotates.

Referring to <FIG>, the axle shafts <NUM> may transmit torque from the differential assembly <NUM> to corresponding wheel hubs and wheels. The axle shafts <NUM> may extend along and may be rotatable about an axis, which may be the differential axis <NUM>. Each axle shaft <NUM> may have a first end and a second end. The first end may be operatively connected to the differential assembly <NUM>. The second end may be disposed opposite the first end and may be operatively connected to a wheel.

Referring to <FIG>, an example of an interaxle differential unit <NUM> is shown. The interaxle differential unit <NUM> may accommodate or compensate for rotational speed differences between different drive axle assemblies, such as speed differences between the axle assembly <NUM> and a second axle assembly that is connected in series with the axle assembly <NUM>. The interaxle differential unit <NUM> may be provided in various locations. In <FIG>, the interaxle differential unit <NUM> is disposed inside the differential carrier <NUM> on the input shaft <NUM>; however, it is contemplated that the interaxle differential unit <NUM> may be provided in other locations, such as closer to the output yoke <NUM> or with the second axle assembly. It is also contemplated that interaxle differential unit <NUM> may be disposed on a shaft other than the input shaft <NUM>. In at least one configuration, the interaxle differential unit <NUM> may include a case <NUM> that may receive an interaxle differential unit gear nest. The interaxle differential unit gear nest may include a plurality of gears that may operatively connect the input shaft <NUM> to the output shaft <NUM>. In at least one configuration, the interaxle differential unit gear nest may include a side gear <NUM>, the spider <NUM>, and one or more pinion gears <NUM>.

The side gear <NUM> may partially extend into the case <NUM>. The side gear <NUM> may be mounted to the output shaft <NUM>. As such, the side gear <NUM> may be rotatable about the first axis <NUM> with the output shaft <NUM>.

The spider <NUM> may be fixedly disposed on the input shaft <NUM>. For instance, the spider <NUM> may include a center bore that may include splines that may mate with corresponding splines on the input shaft <NUM> to help align and secure the spider <NUM> to the input shaft <NUM>. As such, the spider <NUM> may rotate about the first axis <NUM> with the input shaft <NUM>. The spider <NUM> may also include one or more pins that may extend away from the center bore of the spider <NUM>.

One or more pinion gears <NUM> may be rotatable with respect to the spider <NUM>. For instance, a pinion gear <NUM> may be rotatably disposed on a pin of the spider <NUM>. The pinion gear <NUM> may include teeth that may mesh or mate with the side gear teeth <NUM> of the first gear <NUM> and may mesh or mate with teeth of the side gear <NUM>.

Referring to <FIG>, the output shaft <NUM> may extend along and may be configured to rotate about an axis, such as the first axis <NUM>. For instance, the output shaft <NUM> may be supported by one or more bearings that may be disposed on the axle housing <NUM>, such as an output shaft bearing <NUM>. The output shaft bearing <NUM> may be mounted to the axle housing <NUM> and may encircle the output shaft <NUM>. The output shaft <NUM> may be fixedly coupled to the side gear <NUM>.

Referring to <FIG> and <FIG>, the output yoke <NUM> may facilitate coupling of the axle assembly <NUM> to another axle assembly. For instance, the output yoke <NUM> may be fixedly coupled to the output shaft <NUM> and may be operatively connected to a second axle assembly in any suitable manner, such as via a prop shaft. As is best shown in <FIG>, an output seal <NUM> may be disposed adjacent to the output yoke <NUM>. For instance, the output seal <NUM> may be at least partially received inside a hole in the axle housing <NUM> and may encircle the output yoke <NUM>. It is contemplated that the output yoke <NUM> and the output seal <NUM> may be omitted in various configurations.

Referring to <FIG> and <FIG>, lubricant reservoir <NUM> may be disposed above the differential assembly <NUM>. The lubricant reservoir <NUM> may capture lubricant <NUM> that is splashed by the differential assembly <NUM>. For instance, the lubricant reservoir <NUM> may capture lubricant <NUM> that is splashed by the ring gear <NUM> as the ring gear <NUM> rotates about the differential axis <NUM>. The lubricant reservoir <NUM> may be positioned above the first axis <NUM>. In addition, the lubricant reservoir <NUM> may be received inside the axle housing <NUM> such that the lubricant reservoir <NUM> may be spaced apart from the bowl cover <NUM>. The lubricant reservoir <NUM> may have a unitary configuration or may be configured as a one-piece component. In at least one configuration and as is best shown with reference to <FIG>, the lubricant reservoir <NUM> may have a first tank <NUM>, a second tank <NUM>, a main panel <NUM>, a bridge <NUM>, and a lip <NUM>.

Referring to <FIG>, the first tank <NUM> may be disposed above the output shaft <NUM> and the first axis <NUM>. In at least one configuration, the teeth of the ring gear <NUM> may face toward the first tank <NUM>. As is best shown in <FIG>, the first tank <NUM> may have an upward facing inlet <NUM> that may receive splashed lubricant and at least one outlet <NUM>. The first tank <NUM> may be defined by a plurality of panels. For instance, the first tank <NUM> may be at least partially defined by the main panel <NUM> and may be further defined by an end panel <NUM>, a bottom panel <NUM>, a ramp panel <NUM>, a ledge panel <NUM>, an inboard panel <NUM>, an outboard panel <NUM>, or combinations thereof.

The end panel <NUM> may be disposed opposite the main panel <NUM> and may be spaced apart from the main panel <NUM>. As such, the end panel <NUM> may face away from the axle housing <NUM>, the differential carrier <NUM>, or both. The end panel <NUM> may extend upward from the bottom panel <NUM>. In at least one configuration, the end panel <NUM> may be disposed substantially parallel to the main panel <NUM>.

The bottom panel <NUM> may extend between the main panel <NUM> and the end panel <NUM>. For instance, the bottom panel <NUM> may extend from the main panel <NUM> to the end panel <NUM>. The bottom panel <NUM> may be disposed closer to the differential axis <NUM> than other panels of the first tank <NUM>. As is best shown in <FIG>, the bottom panel <NUM> may slope downward from the end panel <NUM> to the main panel <NUM>.

Referring to <FIG> and <FIG>, the ramp panel <NUM> may extend between the bottom panel <NUM> and the ledge panel <NUM>. In at least one configuration, the ramp panel <NUM> may extend at an angle such that the ramp panel <NUM> may extend further from the differential axis <NUM> or further upward as the distance from the ring gear <NUM> increases.

The ledge panel <NUM> may extend between the ramp panel <NUM> and the outboard panel <NUM>. The ledge panel <NUM> may be positioned further above the differential axis <NUM> than the bottom panel <NUM>. The ledge panel <NUM> may be disposed directly above the output shaft <NUM> and the first axis <NUM>. In at least one configuration, the ledge panel <NUM> may extend substantially parallel to the first axis <NUM>.

Referring primarily to <FIG> and <FIG>, the inboard panel <NUM> may extend from the main panel <NUM> to the end panel <NUM>. In addition, the inboard panel <NUM> may extend from the bottom panel <NUM> to the bridge <NUM>. The inboard panel <NUM> may face toward the ring gear <NUM>.

The outboard panel <NUM> may be disposed opposite the inboard panel <NUM> and may be spaced apart from the inboard panel <NUM>. The outboard panel <NUM> may extend from the main panel <NUM> to the end panel <NUM>. In addition, the outboard panel <NUM> may extend from the ledge panel <NUM> to the upward facing inlet <NUM> and to the lip <NUM>. The outboard panel <NUM> may follow the curvature of the interior side of the center portion <NUM> of the axle housing <NUM>.

Referring primarily to <FIG> and <FIG>, the second tank <NUM> may be spaced apart from the first tank <NUM>. The ring gear <NUM> may be positioned between and may extend between the first tank <NUM> and the second tank <NUM>. The second tank <NUM> may be disposed above a differential bearing support <NUM>. The second tank <NUM> may hold the same volume of lubricant <NUM> or a different volume of lubricant <NUM> as compared to the first tank <NUM>. In the configuration shown, the second tank <NUM> has a greater volume than the first tank <NUM>. The second tank <NUM> may have an upward facing inlet <NUM>' that may receive splashed lubricant and at least one outlet <NUM>'. The second tank <NUM> may be defined by a plurality of panels. For instance, the second tank <NUM> may be at least partially defined by the main panel <NUM> and may be further defined by an end panel <NUM>', a bottom panel <NUM>', a ramp panel <NUM>', an inboard panel <NUM>', an outboard panel <NUM>', or combinations thereof.

The end panel <NUM>' may be disposed opposite the main panel <NUM> and may be spaced apart from the main panel <NUM>. As such, the end panel <NUM>' may face away from the axle housing <NUM>, the differential carrier <NUM>, or both. The end panel <NUM>' may extend upward from the bottom panel <NUM>'. In at least one configuration, the end panel <NUM>' may be disposed substantially parallel to the main panel <NUM> in may be coplanar with the end panel <NUM> of the first tank <NUM>. In the configuration shown, the outlet <NUM>' of the second tank <NUM> is provided with the end panel <NUM>'; however, it is contemplated that the outlet <NUM>' may be provided with other panels of the second tank <NUM>.

The bottom panel <NUM>' may extend between the main panel <NUM> and the end panel <NUM>'. For instance, the bottom panel <NUM>' may extend from the main panel <NUM> to the end panel <NUM>'. The bottom panel <NUM>' may be disposed closer to the differential axis <NUM> than other panels of the second tank <NUM>. In at least one configuration, the bottom panel <NUM>' may be disposed directly above a differential bearing support <NUM>. As is best shown in <FIG>, the bottom panel <NUM>' may slope downward from the main panel <NUM> to the end panel <NUM>'. In addition, the bottom panel <NUM> of the first tank <NUM> may be disposed further above the sump portion <NUM> than the bottom panel <NUM>' of the second tank <NUM> is disposed from the sump portion <NUM>. In one or more configurations, the bottom panel <NUM> may be disposed above the first axis <NUM> while the bottom panel <NUM>' may be disposed below the first axis <NUM>.

Referring to <FIG> and <FIG>, the ramp panel <NUM>' may extend between the bottom panel <NUM>' and the outboard panel <NUM>'. In at least one configuration, the ramp panel <NUM>' may extend at an angle such that the ramp panel <NUM>' may extend further from the differential axis <NUM> or further upward as the distance from the ring gear <NUM> increases.

The inboard panel <NUM>' may extend from the main panel <NUM> to the end panel <NUM>'. In addition, the inboard panel <NUM>' may extend from the bottom panel <NUM>' to the bridge <NUM>. The inboard panel <NUM>' may face toward the ring gear <NUM>. In at least one configuration and as is best shown in <FIG>, the inboard panel <NUM>' may have a nonplanar configuration and may be configured such that at least a portion of the inboard panel <NUM>' extends toward the first tank <NUM> as the distance from the differential axis <NUM> increases.

The outboard panel <NUM>' may be disposed opposite the inboard panel <NUM>' and may be spaced apart from the inboard panel <NUM>'. The outboard panel <NUM>' may extend from the main panel <NUM> to the end panel <NUM>'. In addition, the outboard panel <NUM>' may extend from the ramp panel <NUM>' to the upward facing inlet <NUM>' and to the lip <NUM>. The outboard panel <NUM>' may follow the curvature of the interior side of the center portion <NUM> of the axle housing <NUM>.

Referring primarily to <FIG> and <FIG>, the main panel <NUM> may partially define the first tank <NUM> and the second tank <NUM>. The main panel <NUM> may face toward the differential carrier <NUM> and may engage the center portion <NUM> of the axle housing <NUM>. In addition, the main panel <NUM> may extend in a vertical direction from the bridge <NUM> to the lip <NUM>. In at least one configuration, the main panel <NUM> may be disposed substantially perpendicular to the first axis <NUM> and may include one or more indentations that may receive the ends of fasteners that may couple the differential carrier <NUM> to the axle housing <NUM>. In the configuration shown, the outlet <NUM> of the first tank <NUM> is provided with the main panel <NUM>; however, it is contemplated that the outlet <NUM> may be provided with other panels of the first tank <NUM>.

The bridge <NUM> may interconnect the first tank <NUM> and the second tank <NUM>. The bridge <NUM> may extend above and may extend over the ring gear <NUM>. In addition, the bridge <NUM> may direct lubricant <NUM> that is splashed by the ring gear <NUM> and that lands on top of the bridge <NUM> to the first tank <NUM> and the second tank <NUM>. For instance as is best shown in <FIG>, the bridge <NUM> may be crowned or may protrude upward at a location that is disposed directly above the ring gear <NUM> and thus at least a portion of the bridge <NUM> may be sloped away from the protrusion and toward the first tank <NUM>, the second tank <NUM>, or both.

Referring primarily to <FIG>, the lip <NUM> may be disposed proximate the top of the lubricant reservoir <NUM>. The lip <NUM> may extend from the main panel <NUM> in a direction that extends over the first tank <NUM>, second tank <NUM>, the bridge <NUM>, or combinations thereof. The lip <NUM> may engage the inner side of the center portion <NUM> of the axle housing <NUM> and may extend from the first tank <NUM> to the second tank <NUM>. For instance, the lip <NUM> may extend from the outboard panel <NUM> of the first tank <NUM> over the bridge <NUM> and to the outboard panel <NUM>' of the second tank <NUM>.

Referring to <FIG> and <FIG>, the first conduit <NUM> may be fluidly connected to the outlet <NUM> of the first tank <NUM>. The first conduit <NUM> is hidden behind the output shaft <NUM> from the perspective shown in <FIG>. The first conduit <NUM> may have any suitable configuration. For instance the first conduit <NUM> may be configured as a tube, pipe, conduit, channel, hose, or the like. In at least one configuration, the first conduit <NUM> may route lubricant from the first tank <NUM> to the input seal <NUM>, the input shaft bearing <NUM>, or combinations thereof. For instance, the first conduit <NUM> may extend between the main panel <NUM> and the input shaft bearing <NUM>.

The second conduit <NUM> may be fluidly connected to the outlet <NUM>' of the second tank <NUM>. The second conduit <NUM> is hidden behind the output shaft <NUM> from the perspective shown in <FIG>. The second conduit <NUM> may have any suitable configuration as previously discussed with respect to the first conduit <NUM>. In at least one configuration, the second conduit <NUM> may route lubricant <NUM> from the second tank <NUM> to the output shaft bearing <NUM>, the output seal <NUM>, or combinations thereof. For instance, the second conduit <NUM> may extend between the end panel <NUM>' of the second tank <NUM> and the output shaft bearing <NUM>. The first conduit <NUM>, the second conduit <NUM>, or both may be sloped downward away from the lubricant reservoir <NUM> to further facilitate the flow of lubricant <NUM> in one or more configurations. As such, the first tank <NUM> and the first conduit <NUM> may lubricate different components than the second tank <NUM> and the second conduit <NUM>. This may be accomplished by having a single conduit may extend from each tank <NUM>, <NUM>.

Referring to <FIG>, another configuration for distributing lubricant in an axle assembly is shown. <FIG> is similar to <FIG> but is illustrated as a side view rather than a section view and omits the perimeter of the housing assembly <NUM> for clarity. This configuration includesa lubricant reservoir <NUM>' and a lubricant distribution trough <NUM>.

The lubricant reservoir <NUM>' may have a similar configuration or the same configuration as the lubricant reservoir <NUM> previously discussed. For instance, the lubricant reservoir <NUM>' may have one or more tanks and may receive lubricant <NUM> that is splashed by the differential assembly <NUM>. At least one tank of the lubricant reservoir <NUM>' may provide lubricant <NUM> to the lubricant distribution trough <NUM> via a conduit, such as the first conduit <NUM>'.

The lubricant distribution trough <NUM> receives lubricant <NUM> from the lubricant reservoir <NUM>'. The lubricant distribution trough <NUM> may be positioned at a lower elevation than the lubricant reservoir <NUM>'. In at least one configuration, the lubricant distribution trough <NUM> includes a first trough <NUM>, a second trough <NUM>, and a dam <NUM>. The lubricant levels in the lubricant distribution trough <NUM> are examples and may be higher or lower than what is depicted.

The first trough <NUM> receives lubricant <NUM> from the lubricant reservoir <NUM>'. For instance, lubricant <NUM> that exits the first conduit <NUM>' may flow into the first trough <NUM>. The first trough <NUM> may have an outlet that may provide or direct lubricant <NUM> to the input seal <NUM>, the input shaft bearing <NUM>, or both. Flow of lubricant through the outlet is represented by the arrowed line extending from the left end of the first trough <NUM>.

The second trough <NUM> is disposed below the first trough <NUM>. As such, the bottom of the second trough <NUM> or a portion thereof may be provided at a lower elevation than the bottom of the first trough <NUM>. In the configuration shown, the bottom of the second trough <NUM> is disposed below the first axis <NUM> while the bottom of the first trough <NUM> is disposed above the first axis <NUM>. The second trough <NUM> may provide lubricant <NUM> to components that may be located between the input shaft bearing <NUM> and the differential assembly <NUM>. For instance, the second trough <NUM> may provide lubricant <NUM> to the drop gear set <NUM>, the interaxle differential unit <NUM>, or both. In at least one configuration, the second trough <NUM> may be divided into an upper portion <NUM> and a lower portion <NUM>.

The upper portion <NUM> may extend from the dam <NUM> to the lower portion <NUM>. The upper portion <NUM> may be elevated with respect to the lower portion <NUM>. For instance, the upper portion <NUM> may be positioned at a lower elevation than the first trough <NUM> and at a higher elevation than the lower portion <NUM>. In at least one configuration, the upper portion <NUM> may have outlets that may provide lubricant <NUM> to the drop gear set <NUM>, the interaxle differential unit <NUM>, bearings that support these components, or combinations thereof. The outlets are represented by the arrowed lines extending downward from the bottom of the upper portion <NUM>.

The lower portion <NUM>, if provided, may extend from the upper portion <NUM> toward the differential assembly <NUM>. In at least one configuration, the lower portion <NUM> may receive lubricant <NUM> that is splashed by the differential assembly <NUM> as represented by the curved arrowed line near the right end of the lower portion <NUM>.

The dam <NUM> separates the first trough <NUM> from the second trough <NUM>. The dam <NUM> may protrude upward above the bottom of the first trough <NUM>. As such, lubricant <NUM> that enters the first trough <NUM> may be temporarily stored in the first trough <NUM>. Lubricant <NUM> may exit the first trough <NUM> in two main ways. First, lubricant <NUM> may exit the first trough <NUM> through an outlet to lubricate the input seal <NUM>, input shaft bearing <NUM>, or both as previously discussed. In addition, lubricant <NUM> may flow over the top of the dam <NUM> when the level of lubricant <NUM> exceeds the volume of lubricant <NUM> that can be stored behind the dam <NUM>. The volume of lubricant <NUM> that is provided to the first trough <NUM> when the differential assembly <NUM> is rotating at moderate to high speeds may exceed the storage capacity of the first trough <NUM>, resulting in lubricant <NUM> overflowing the top of the dam <NUM> and spilling into the second trough <NUM>. Excess lubricant <NUM> may exit the second trough <NUM> and spill into the sump portion <NUM>. The lubricant reservoir <NUM>' may empty when the differential assembly <NUM> is stationary and lubricant <NUM> is not being splashed into the lubricant reservoir <NUM>'. As a result, the flow of lubricant <NUM> from the lubricant reservoir <NUM>' to the first trough <NUM> may decrease at lower rotational speeds and may stop once the lubricant reservoir <NUM>' is empty. Lubricant <NUM> that is captured behind the dam <NUM> may not overtop the dam <NUM> but instead may exit through the outlet to lubricate components such as the input shaft bearing <NUM> even though splashed lubrication is not being provided to the first trough <NUM>. In addition or alternatively, lubricant <NUM> provided to the lubricant distribution trough <NUM> may be routed to lubricate various components for a limited period of time such as during low-speed operating conditions during which little splash lubrication is available.

The flow rate through any of the outlets of the lubricant distribution trough <NUM> may be actively or passively controlled to help provide lubricant <NUM> to various components over an extended period of time.

Optionally, the lubricant reservoir <NUM>', the second trough <NUM>, or both, may have a second conduit <NUM>' that may provide lubricant to the output shaft bearing <NUM>, output seal <NUM>, or both. It is also contemplated that the second conduit <NUM>' may be omitted and the second trough <NUM> may be open-ended. It is also contemplated, that the second conduit may be configured as in <FIG> and may receive lubricant from the lubricant reservoir <NUM>' rather than the lubricant distribution trough <NUM>.

An axle assembly as described above may allow a lubricant reservoir to be provided at an elevated location where splashed lubricant may be captured. Capturing lubricant in a lubricant reservoir disposed outside of the sump portion may help reduce drag and churning losses on the differential assembly, which may help improve the operating efficiency of the axle assembly. Captured lubricant may be distributed to components that are remotely located from the differential assembly and that may be positioned in locations where splashed lubricant may not reach in sufficient quantities. Moreover, an axle assembly as described above may store lubricant and help lubricate components when the differential assembly is not rotating. For instance, if torque is not provided to the differential assembly such as by disengaging torque transmission through the drop gear set and by disconnecting the differential assembly from its associated wheels, then the differential assembly may not rotate and splash lubricant. However, components such as the input shaft, output shaft, interaxle differential unit, and associated bearings may still rotate as torque is transmitted from one axle assembly to another. The present invention may store and distribute lubricant to these components and bearings associated with these components to help reduce friction, reduce wear, and reduce operating temperatures, which may help increase component life.

Claim 1:
An axle assembly (<NUM>) comprising:
a differential assembly (<NUM>) that is rotatable about an axis (<NUM>) and that has a ring gear (<NUM>);
a housing assembly (<NUM>) that receives the differential assembly (<NUM>);
a lubricant reservoir (<NUM>') that is disposed above the differential assembly (<NUM>) and that captures lubricant (<NUM>) that is splashed by the ring gear (<NUM>); and
a lubricant distribution trough (<NUM>) that receives lubricant (<NUM>) from the lubricant reservoir (<NUM>'), the lubricant distribution trough (<NUM>) including:
a first trough (<NUM>) that receives lubricant (<NUM>) from the lubricant reservoir (<NUM>');
a second trough (<NUM>) that is disposed below the first trough (<NUM>); and
a dam (<NUM>) that separates the first trough (<NUM>) from the second trough (<NUM>).