Patent Description:
An axle assembly having a drive pinion is disclosed in <CIT> <CIT> discloses a carrier assembly for a forward drive axle that has a pinion gear that has a two-piece design that is operatively coupled to an inter-axle differential.

In at least one embodiment, an axle assembly is provided as set out in claim <NUM>.

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 that may be connected in series with a linkage, such as a prop shaft. As such, torque may be transmitted from a first axle assembly to a second axle assembly that is connected in series with the first axle assembly. As is best shown with reference to <FIG> and <FIG>, the axle assembly <NUM> may include a housing assembly <NUM>, an interaxle differential unit <NUM>, a differential assembly <NUM>, and at least one axle shaft <NUM>.

The housing assembly <NUM> may include an axle housing <NUM> and a differential carrier <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>. The center portion <NUM> may define a cavity that may receive the differential assembly <NUM>. A lower region of the center portion <NUM> may at least partially define a sump portion that may contain lubricant. Splashed lubricant may flow down the sides of the center portion <NUM> and may flow over internal components of the axle assembly <NUM> and gather in the sump portion.

The center portion <NUM> may include a carrier mounting surface. The carrier mounting surface may face toward and may engage the differential carrier <NUM>. The carrier mounting surface may facilitate mounting of the differential carrier <NUM> to the axle housing <NUM>. For example, the carrier mounting surface may have a set of holes that may be aligned with corresponding holes on the differential carrier <NUM>. Each hole may receive a fastener, such as a bolt, that may couple the differential carrier <NUM> to the axle housing <NUM>.

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 substantially similar configurations. For example, the arm portions <NUM> may each have a hollow configuration or tubular configuration that may extend around the 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>.

Referring to <FIG> and <FIG>, the differential carrier <NUM>, which may also be called a carrier housing, may be mounted to the center portion <NUM> of the axle housing <NUM>. The differential carrier <NUM> may receive the interaxle differential unit <NUM> and may support the differential assembly <NUM>. The differential carrier <NUM> may be configured as a single component or as multiple components that are assembled to each other. For instance, the differential carrier may include a first portion that is mounted to the axle housing <NUM> and a second portion that is mounted to the first portion that may receive the interaxle differential unit <NUM>. As is best shown in <FIG>, the differential carrier <NUM> may have a flange portion <NUM> and one or more bearing supports <NUM>.

Referring to <FIG> and <FIG>, the flange portion <NUM> may facilitate mounting of the differential carrier <NUM> to the axle housing <NUM>. For example, the flange portion <NUM> may be disposed on the carrier mounting surface of the axle housing <NUM> and may have a set of holes that may receive fasteners as previously discussed.

Referring to <FIG>, the bearing support <NUM> may receive a roller bearing assembly <NUM> that may rotatably support the differential assembly <NUM>. For example, two bearing supports <NUM> may be received in the center portion <NUM> and may be located proximate opposite sides of the differential assembly <NUM>. The bearing support <NUM> may be provided in various configurations. For example, a bearing support <NUM> may include a pair of legs that extend from the differential carrier <NUM> and a bearing cap. The bearing cap may be mounted to the legs and may arch over a roller bearing assembly <NUM>. In such a configuration, the bearing support <NUM> and bearing cap may cooperate to extend around, receive, and secure the roller bearing assembly <NUM>. As another example, the bearing support <NUM> may be received inside a roller bearing assembly <NUM> which in turn may support the differential assembly <NUM>.

Referring to <FIG>, additional components that may be associated with the differential assembly <NUM> may include an input yoke <NUM>, an input shaft <NUM>, a drive pinion assembly <NUM>, an output shaft <NUM>, and an output yoke <NUM>.

Referring to <FIG>, the input yoke <NUM> may facilitate coupling of the axle assembly <NUM> to a torque source. For example, the input yoke <NUM> may be coupled to the drive shaft. The input yoke <NUM> may be disposed on the input shaft <NUM>, the input shaft <NUM> being best shown in <FIG>. For example, the input yoke <NUM> may have an opening that receives the input shaft <NUM> and may be secured to the input shaft <NUM> with a nut.

Referring to <FIG> and <FIG>, the input shaft <NUM> may extend along and may be configured to rotate about a first axis <NUM>. For example, the input shaft <NUM> may be rotatably supported by one or more roller bearing assemblies <NUM> that may be disposed on the differential carrier <NUM>. The input shaft <NUM> may be part of the interaxle differential unit <NUM> or may be operatively connected to the interaxle differential unit <NUM>. For instance, the input shaft <NUM> may be integrally formed with a case of the interaxle differential unit <NUM> or may be provided as a separate component that is operatively connected or fixedly coupled to the case.

Referring to <FIG>, the drive pinion assembly <NUM> may provide torque to a ring gear <NUM> that may be provided with the differential assembly <NUM>. The drive pinion assembly <NUM> may extend around and may be rotatable about a first axis <NUM>. The ring gear <NUM> may rotate about a second axis <NUM>. The drive pinion assembly <NUM> may be coaxially disposed with the input shaft <NUM> and may be spaced apart from the input shaft <NUM>. The drive pinion assembly <NUM> may be rotatably supported by one or more roller bearing assemblies <NUM> that may be disposed on the differential carrier <NUM>. In <FIG>, two roller bearing assemblies <NUM> are shown that are spaced apart from each other and separated by a spacer ring <NUM> that may extend around the drive pinion assembly <NUM>. As is best shown with reference to <FIG>, the drive pinion assembly <NUM> may include a drive pinion body <NUM>, a pinion gear <NUM>, a side gear <NUM>, and a nut <NUM>.

The drive pinion body <NUM> may along the first axis <NUM>. In at least one configuration, the drive pinion body <NUM> may include a first end portion <NUM>, a second end portion <NUM>, an inner drive pinion surface <NUM>, a drive pinion passage <NUM>, and a drive pinion outer surface <NUM>.

The first end portion <NUM> may be disposed at a first end of the drive pinion body <NUM>. The first end portion <NUM> may support the pinion gear <NUM> and may extend through a pinion gear hole in the pinion gear <NUM>. As such, the drive pinion body <NUM> and the drive pinion passage <NUM> may extend completely through the pinion gear hole in the pinion gear <NUM>. In at least one configuration, the first end portion <NUM> may include a first end surface <NUM>, a threaded portion <NUM>, a first spline <NUM>, a first step surface <NUM>, an intermediate surface <NUM>, and a second step surface <NUM>.

The first end surface <NUM> may be disposed at a first end of the drive pinion body <NUM>. The first end surface <NUM> may extend from the inner drive pinion surface <NUM> to or toward the threaded portion <NUM>.

The threaded portion <NUM> may be disposed opposite the inner drive pinion surface <NUM> and the drive pinion passage <NUM>. The threaded portion <NUM> may protrude out of a pinion gear hole of the pinion gear <NUM>. The nut <NUM> may threadingly engage the threaded portion <NUM> to secure the pinion gear <NUM> to the drive pinion body <NUM> and inhibit axial movement of the pinion gear <NUM> along the first axis <NUM> in a direction that extends toward the first end surface <NUM>.

The first spline <NUM> may be axially positioned between the threaded portion <NUM> and the first step surface <NUM>. The first spline <NUM> may include a plurality of teeth that may extend away from the drive pinion passage <NUM>. The teeth may be disposed substantially parallel to the first axis <NUM> and may mate with a corresponding spline on a pinion gear <NUM> as will be discussed in more detail below.

The first step surface <NUM> may be axially positioned between the first spline <NUM> and the intermediate surface <NUM>. The first step surface <NUM> may extend away from the first axis <NUM> and may generally extend from the first spline <NUM> to the intermediate surface <NUM>.

The intermediate surface <NUM> may be axially positioned between the first step surface <NUM> and the second step surface <NUM>. The intermediate surface <NUM> may have a larger diameter than the first spline <NUM> or may extend further away from the first axis <NUM> than the first spline <NUM>. The intermediate surface <NUM> may be substantially cylindrical and may be at least partially disposed inside the pinion gear hole of the pinion gear <NUM>. The intermediate surface <NUM> may engage and support the pinion gear <NUM>.

The second step surface <NUM> may be axially positioned between the intermediate surface <NUM> and the drive pinion outer surface <NUM>. The second step surface <NUM> may extend away from the first axis <NUM> and may extend from the intermediate surface <NUM> to the drive pinion outer surface <NUM>.

The second end portion <NUM> is disposed opposite the first end portion <NUM>. In addition, the second end portion <NUM> may be disposed at a second end of the drive pinion body <NUM> that may be disposed opposite the first end. The second end portion <NUM> may include or may support the side gear <NUM> as will be discussed in more detail below. In at least one configuration, the second end portion <NUM> may include a second end surface <NUM>.

Referring to <FIG> and <FIG>, the second end surface <NUM> may be disposed opposite the first end surface <NUM>. As such, the second end surface <NUM> may be disposed at a second end of the drive pinion body <NUM>. The second end surface <NUM> may extend from the inner drive pinion surface <NUM> in a direction that extends away from the first axis <NUM>.

The inner drive pinion surface <NUM> may extend from the first end surface <NUM> to the second end surface <NUM>. The inner drive pinion surface <NUM> may be a through hole that may extend completely through the drive pinion body <NUM> and may define the drive pinion passage <NUM>. The inner drive pinion surface <NUM> may be spaced apart from the first axis <NUM> and may be radially disposed with respect to the first axis <NUM>. For example, the inner drive pinion surface <NUM> may be an inside circumference of the drive pinion assembly <NUM>. The inner drive pinion surface <NUM> may be spaced apart from and may not engage the output shaft <NUM>.

The drive pinion passage <NUM> may extend along the first axis <NUM>. The output shaft <NUM> may extend through the drive pinion passage <NUM>.

The drive pinion outer surface <NUM> may be disposed opposite the drive pinion passage <NUM>. For example, the drive pinion outer surface <NUM> may face away from the first axis <NUM> and may be an outside circumference of a portion of the drive pinion body <NUM>. In at least one configuration, the drive pinion outer surface <NUM> may extend in an axial direction from the second step surface <NUM> to the side gear <NUM>. The drive pinion outer surface <NUM> may support one or more roller bearing assemblies <NUM>.

Referring to <FIG> and <FIG>, the pinion gear <NUM> may be a separate component from the drive pinion body <NUM>. The pinion gear <NUM> may be fixedly disposed on the drive pinion body <NUM>. For example, the pinion gear <NUM> is fixedly disposed on the first end portion <NUM> and has a pinion gear hole <NUM>. In at least one configuration, the pinion gear <NUM> may have a first gear portion end surface <NUM>, a second gear portion end surface <NUM>, a plurality of pinion gear teeth <NUM>, a pinion gear spline <NUM>, and a stem <NUM>.

The first gear portion end surface <NUM> may be disposed at an end of the pinion gear <NUM>. The first gear portion end surface <NUM> may face toward the differential assembly <NUM>.

The second gear portion end surface <NUM> may be disposed opposite the first gear portion end surface <NUM>. As such, the second gear portion end surface <NUM> may face toward the interaxle differential unit <NUM>. The second gear portion end surface <NUM> may engage a roller bearing assembly <NUM> that may rotatably support the drive pinion assembly <NUM>.

The plurality of pinion gear teeth <NUM> may extend between the first gear portion end surface <NUM> and the second gear portion end surface <NUM>. The teeth may be arranged around the first axis <NUM> and may mate with teeth on the ring gear <NUM>.

The pinion gear hole <NUM> may extend through the pinion gear <NUM> and receives the drive pinion body <NUM>. In at least one configuration, the pinion gear hole <NUM> may receive the pinion gear spline <NUM> and may include a pinion step surface <NUM> and an inner pinion surface <NUM>.

Referring to <FIG>, the pinion step surface <NUM> may be axially positioned between the pinion gear spline <NUM> and the inner pinion surface <NUM>. In addition, the pinion step surface <NUM> may face toward the first step surface <NUM> of the drive pinion body <NUM>. The pinion step surface <NUM> may extend away from the first axis <NUM> and may extend from the pinion gear spline <NUM> to the inner pinion surface <NUM>.

The inner pinion surface <NUM> may be axially positioned between the pinion step surface <NUM> and an end of the pinion gear <NUM>. In a pinion gear configuration that includes a stem <NUM>, the inner pinion surface <NUM> may extend from the pinion step surface <NUM> to an end surface of the stem <NUM>. In a pinion gear configuration that does not include a stem, such as is shown in <FIG>, the inner pinion surface <NUM> may extend from the pinion step surface <NUM> to the second gear portion end surface <NUM>. The inner pinion surface <NUM> may at least partially define an enlarged bore <NUM>. The enlarged bore <NUM> may extend from the pinion gear spline <NUM> may have a larger diameter than the pinion gear spline <NUM>. The intermediate surface <NUM> may be substantially cylindrical and may extend around and may engage the intermediate surface <NUM> of the drive pinion body <NUM>. It is also contemplated that the pinion gear <NUM> may be press-fit onto the drive pinion body <NUM> such that the inner pinion surface <NUM> is press fit against the intermediate surface <NUM>.

The pinion gear spline <NUM> may be disposed in the pinion gear hole <NUM>. The pinion gear spline <NUM> may be axially positioned between the first gear portion end surface <NUM> and the pinion step surface <NUM>. The pinion gear spline <NUM> may include a plurality of teeth that may extend toward the first axis <NUM>. The teeth may be disposed substantially parallel to the first axis <NUM> and may mate with the first spline <NUM> of the drive pinion body <NUM> to inhibit rotation of the pinion gear <NUM> about the first axis <NUM> with respect to the drive pinion body <NUM>.

Optionally, the pinion gear <NUM> may also include a stem <NUM>. The stem <NUM> may have a smaller outside diameter than the pinion gear teeth <NUM> and may extend from the second gear portion end surface <NUM> toward the side gear <NUM> and to a stem end surface <NUM>. The stem end surface <NUM> may face toward the second step surface <NUM> of the drive pinion body <NUM>. The stem <NUM> may partially define the enlarged bore <NUM> and may engage the drive pinion body <NUM>. A roller bearing assembly <NUM> may receive the stem <NUM>. As such, the roller bearing assembly <NUM> may rotatably support the stem <NUM> and hence the drive pinion body <NUM> and may separate the roller bearing assembly <NUM> from the drive pinion body <NUM> such that the roller bearing assembly <NUM> may be spaced apart from and may not engage the drive pinion body <NUM> in one or more embodiments.

Referring to <FIG>, the side gear <NUM> may be disposed on the drive pinion assembly <NUM>. For example, the side gear <NUM> may be fixedly disposed on the second end portion <NUM> of the drive pinion body <NUM>. In the configurations shown in <FIG>, the side gear <NUM> is integrally formed with the drive pinion body <NUM> such that the drive pinion body <NUM> and the side gear <NUM> have unitary one-piece construction and are a unitary one-piece component. Alternatively, the side gear may be a separate component from the drive pinion body as will be discussed in more detail below. Referring to <FIG> and <FIG>, the side gear <NUM> may include a first set of side gear teeth <NUM>, a second set of side gear teeth <NUM>, a side gear end surface <NUM>, an inner side gear surface <NUM>, and a side gear hole <NUM>.

The first set of side gear teeth <NUM> may be arranged around the first axis <NUM> and may face toward the interaxle differential unit <NUM>. The first set of side gear teeth <NUM> may mesh with one or more pinion gears of the interaxle differential unit <NUM> as will be discussed in more detail below.

The second set of side gear teeth <NUM> may be arranged around the first axis <NUM> and may extend radially away from the first axis <NUM>. The second set of side gear teeth <NUM> may be disposed substantially parallel to the first axis <NUM> and may facilitate axial movement of a clutch collar as will be discussed in more detail below.

The side gear end surface <NUM> may be disposed opposite the first set of side gear teeth <NUM>. As such, the side gear end surface <NUM> may face away from the interaxle differential unit <NUM>. An inner race of a roller bearing assembly <NUM> that rotatably supports the drive pinion assembly <NUM> may engage the side gear end surface <NUM>.

The inner side gear surface <NUM> may be disposed opposite the second set of side gear teeth <NUM>. The inner side gear surface <NUM> may be radially disposed with respect to the first axis <NUM> and may at least partially define the side gear hole <NUM>. The inner side gear surface <NUM> may have a larger diameter than the inner drive pinion surface <NUM> and the drive pinion passage <NUM>. The side gear hole <NUM> may partially receive a spider of the interaxle differential unit <NUM> as will be discussed in more detail below. In addition, the inner side gear surface <NUM> may engage and may rotatably support the spider in one or more embodiments.

Referring to <FIG> and <FIG>, another embodiment of a drive pinion assembly <NUM>' is shown. This embodiment is the same as the embodiment shown in <FIG> and <FIG> except that the pinion gear <NUM>' does not include a stem. As such, the roller bearing assembly <NUM> that is disposed adjacent to the pinion gear <NUM>' may receive the drive pinion body <NUM>' and have an inner race that may be disposed on the drive pinion outer surface <NUM> rather than the stem. In addition, the intermediate surface <NUM> of the drive pinion body <NUM>' has a shorter axial length while the drive pinion outer surface <NUM> has a greater axial length.

Referring to <FIG> and <FIG>, another embodiment of a drive pinion assembly <NUM>" is shown. In this embodiment, drive pinion body <NUM>" and the side gear <NUM>" are separate components.

The drive pinion body <NUM>" may have a first end portion <NUM> that may include a first end surface <NUM>, a threaded portion <NUM>, a first spline <NUM>, a first step surface <NUM>, an intermediate surface <NUM>, and a second step surface <NUM> as previously discussed. The second end portion <NUM> may include a second end surface <NUM>", a second spline <NUM>, and a flange <NUM>.

The second end surface <NUM>" may be disposed opposite the first end surface <NUM> and may be received inside the spider of the interaxle differential unit <NUM>.

The second spline <NUM> may be axially positioned between the second end surface <NUM>" and the flange <NUM>. The second spline <NUM> may include a plurality of teeth that may extend away from the drive pinion passage <NUM>. The teeth may be disposed substantially parallel to the first axis <NUM> and may mate with a corresponding spline on the side gear <NUM>".

The flange <NUM> may be disposed between the first end portion <NUM> and the second end portion <NUM>. For example, the flange <NUM> may be axially positioned between the second spline <NUM> and the drive pinion outer surface <NUM>. The flange <NUM> extends away from the first axis <NUM> and may extend further from the first axis <NUM> than the drive pinion outer surface <NUM>. As such, the flange <NUM> may be disposed behind the side gear <NUM>" to inhibit axial movement of the side gear <NUM>" toward the pinion gear <NUM>'. The flange <NUM> may have a first flange surface <NUM> and a second flange surface <NUM>.

The first flange surface <NUM> may face toward the pinion gear <NUM>'. The first flange surface <NUM> may engage an inner race of a roller bearing assembly <NUM> that may rotatably support the drive pinion assembly <NUM>". As such, the flange <NUM> may facilitate providing or setting a preload force on the roller bearing assembly <NUM> adjusting or setting the axial position of the drive pinion assembly <NUM>".

The second flange surface <NUM> may be disposed opposite the first flange surface <NUM>. The second flange surface <NUM> may engage the side gear <NUM>". For example, the second flange surface <NUM> may engage the side gear end surface <NUM>.

The side gear <NUM>" may include a first set of side gear teeth <NUM>, a second set of side gear teeth <NUM>, and a side gear end surface <NUM> as previously described. In addition, the side gear <NUM>" may include a side gear hole <NUM>, a side gear spline <NUM>, and a rim <NUM>.

The side gear hole <NUM> may be a through hole that may extend through the side gear <NUM>". The side gear hole <NUM> may receive the drive pinion body <NUM>".

The side gear spline <NUM> is disposed in the side gear hole <NUM>. The side gear spline <NUM> may extend between the first set of side gear teeth <NUM> and the side gear end surface <NUM>. The side gear spline <NUM> may include a plurality of teeth that may extend toward the first axis <NUM>. The teeth may be disposed substantially parallel to the first axis <NUM> and may mate with the second spline <NUM> of the drive pinion body <NUM>" to inhibit rotation of the side gear <NUM>" about the first axis <NUM> with respect to the drive pinion body <NUM>".

The rim <NUM>, if provided, may extend from the side gear end surface <NUM> toward the roller bearing assembly <NUM>. The rim <NUM> may be disposed adjacent to the second set of side gear teeth <NUM> and may extend at least partially around the flange <NUM> as is best shown in <FIG>.

Referring to <FIG> and <FIG>, another embodiment of a drive pinion assembly <NUM>‴ is shown. In this embodiment, drive pinion body <NUM>‴ and the side gear <NUM>‴ are separate components.

The drive pinion body <NUM>‴ has a first end portion <NUM> that may include a first end surface <NUM>, a threaded portion <NUM>, a first spline <NUM>, a first step surface <NUM>, an intermediate surface <NUM> and a second step surface <NUM> as previously discussed and may also have a second end surface <NUM>". However, the positioning of the second spline <NUM> and flange <NUM> may be reversed. More specifically, the second spline <NUM> may be axially positioned between a roller bearing assembly <NUM> and the flange <NUM> while the flange <NUM> may be axially positioned between the second spline <NUM> and the second end surface <NUM>". As such, the first flange surface <NUM> may face toward the pinion gear <NUM>' and may engage the side gear <NUM>‴ so that the flange <NUM> inhibits inhibit axial movement of the side gear <NUM>‴ in a direction that extends away from the pinion gear <NUM>'. The drive pinion body <NUM>‴ also has a second end portion <NUM> disposed opposite the first end portion <NUM> and is rotatably supportable by one or more roller bearing assemblies <NUM> as previously discussed. As previously discussed, the pinion gear <NUM>, <NUM>' has a pinion gear hole <NUM> that receives the drive pinion body <NUM>‴ and is fixedly disposed on the first end portion <NUM>.

The side gear <NUM>‴ is fixedly disposed on the second end portion <NUM> and includes a side gear hole <NUM> and a side gear spline <NUM> and may include a first set of side gear teeth <NUM>, a second set of side gear teeth <NUM>, and a side gear end surface <NUM>, as previously described, but may not include a rim. The side gear hole <NUM> receives the drive pinion body <NUM>‴ and receives the second spline <NUM> and the flange <NUM>. The side gear spline <NUM> is disposed in the side gear hole <NUM> and mates with the second spline <NUM> disposed on the drive pinion body <NUM>'".

Referring to <FIG> and <FIG>, the output shaft <NUM> may extend along and may be configured to rotate about the first axis <NUM>. For instance, the output shaft <NUM> may be supported by one or more roller bearings that may be disposed on the housing assembly <NUM>. The output shaft <NUM> may extend through the drive pinion assembly and the drive pinion passage <NUM>. In addition, the output shaft <NUM> may extend through a spider of the interaxle differential unit <NUM> as will be discussed in more detail below. The output shaft <NUM> may be coupled to the interaxle differential unit <NUM> at a first end. For example, the output shaft <NUM> may be fixedly coupled to a second side gear of the interaxle differential unit <NUM>. The output shaft <NUM> may be fixedly coupled to the output yoke <NUM> at a second end that may be disposed opposite the first end.

Referring to <FIG>, the output yoke <NUM> may facilitate coupling of the output shaft <NUM> to a second axle assembly that may be disposed in series with the axle assembly <NUM>. For instance, the output yoke <NUM> may be coupled to a connecting shaft, such as a prop shaft, which in turn may be operatively connected to the second axle assembly.

Referring to <FIG>, the interaxle differential unit <NUM> may operatively connect the input shaft <NUM> to the drive pinion assembly <NUM>, <NUM>', <NUM>", <NUM>‴ and/or the output shaft <NUM>. The interaxle differential unit <NUM> may compensate for speed differences between different drive axle assemblies, such as speed differences between the axle assembly <NUM> and a second axle assembly. As is best shown with reference to <FIG> and <FIG>, the interaxle differential unit <NUM> may include a case <NUM>, a clutch collar <NUM>, a second side gear <NUM>, a spider <NUM>, a plurality of pinion gears <NUM>, a thrust bearing <NUM>, and an optional stabilizer bearing <NUM>.

The case <NUM> may be configured to receive components of the interaxle differential unit <NUM>. In addition, the case <NUM> may be rotatable about the first axis <NUM>. In at least one configuration, the case <NUM> may include a first case portion <NUM> and a second case portion <NUM> that may cooperate to at least partially define a cavity. The cavity may at least partially receive the side gear <NUM>, <NUM>", <NUM>"', second side gear <NUM>, spider <NUM>, pinion gears <NUM>, thrust bearing <NUM>, and the stabilizer bearing <NUM>.

Referring to <FIG> and <FIG>, the first case portion <NUM> may receive at least a portion of the interaxle differential unit <NUM>. In the configuration shown, the first case portion <NUM> is configured as a unitary or one piece component that includes the input shaft <NUM> and a first spider receiving portion <NUM>.

Referring to <FIG>, the first spider receiving portion <NUM> may extend away from the first axis <NUM> and toward the second case portion <NUM>. As is best shown in <FIG>, the first spider receiving portion <NUM> may extend around a portion of the interaxle differential unit <NUM>. The first spider receiving portion <NUM> may include a plurality of fastener holes <NUM> that may be arranged around the first axis <NUM>. Each fastener holes <NUM> may be configured as a through hole that may receive a corresponding fastener <NUM>, such as a bolt, that may fixedly couple the first case portion <NUM> to the second case portion <NUM>. The first spider receiving portion <NUM> may also include a first end surface <NUM> that may face toward and may engage the second case portion <NUM>.

Referring to <FIG> and <FIG>, the second case portion <NUM> may be disposed opposite the first case portion <NUM> and may receive at least a portion of the interaxle differential unit <NUM>. The second case portion <NUM> may be configured as a ring that may extend around the first axis <NUM> and may include plurality of fastener holes <NUM> and a face gear <NUM>.

The fastener holes <NUM> may be aligned with corresponding fastener holes <NUM> on the first case portion <NUM> and may receive a corresponding fastener <NUM>. The fastener holes <NUM> may extend from a second end surface <NUM> that may face toward and may engage the first end surface <NUM>.

The face gear <NUM> may be disposed opposite the second end surface <NUM>. The face gear <NUM> may include a plurality of teeth that may be arranged around the first axis <NUM>. The teeth may extend away from the first case portion <NUM> toward a clutch collar <NUM>.

Referring to <FIG>, the clutch collar <NUM>, which may also be referred to as a lock collar, may be moveably disposed on the side gear <NUM>, <NUM>', <NUM>". The clutch collar <NUM> may move axially or move along the first axis <NUM> between a retracted position and an extended position as will be discussed in more detail below. As is best shown in <FIG>, the clutch collar <NUM> may be generally ring-shaped and may include a clutch collar hole <NUM>, a clutch collar face gear <NUM>, and a clutch collar groove <NUM>.

The clutch collar hole <NUM> may extend through the clutch collar <NUM> and extend around the first axis <NUM>. The clutch collar hole <NUM> may receive the side gear <NUM>, <NUM>', <NUM>". For example, the clutch collar <NUM> may have a spline that may extend into the clutch collar hole <NUM> and toward the first axis <NUM> and may mate with the second set of side gear teeth <NUM> of the side gear <NUM>, <NUM>", <NUM>‴. As such, the mating splines may allow the clutch collar <NUM> to move in an axial direction or along the first axis <NUM> while inhibiting rotation of the clutch collar <NUM> about the first axis <NUM> with respect to the side gear <NUM>, <NUM>", <NUM>‴.

The clutch collar face gear <NUM> may include a set of teeth that may face toward the interaxle differential unit <NUM>. The set of teeth may be arranged around the first axis <NUM> and may selectively engage the teeth of the face gear <NUM> of the second case portion <NUM> depending on the position of the clutch collar <NUM>.

The clutch collar groove <NUM> may face away from the first axis <NUM> and may extend around the first axis <NUM>. The clutch collar groove <NUM> may receive a shift fork <NUM>, which is best shown in <FIG>, that may operatively connect the clutch collar <NUM> to an actuator. The actuator may move the clutch collar <NUM> between an unlocked position and a locked position. The clutch collar face gear <NUM> may not engage the face gear <NUM> when the clutch collar <NUM> is in the unlocked position. As such, the drive pinion assembly <NUM>, <NUM>', <NUM>", <NUM>‴ may be permitted to rotate with respect to the case <NUM>. The clutch collar face gear <NUM> may engage and mesh with the face gear <NUM> when the clutch collar <NUM> is in the locked position, thereby inhibiting the drive pinion assembly <NUM>, <NUM>', <NUM>", <NUM>‴ from rotating with respect to the case <NUM>.

Referring to <FIG>, the first case portion <NUM> may cooperate with the second case portion <NUM> to define one or more spider shaft holes <NUM>. The spider shaft holes <NUM> may be generally disposed extend between the first end surface <NUM> of the first case portion <NUM> and the second end surface <NUM> of the second case portion <NUM>. A spider shaft hole <NUM> may receive a shaft of the spider <NUM> as will be discussed in more detail below. In the configuration shown, three spider shaft holes <NUM> are shown; however, it is contemplated that a greater or lesser number of spider shaft holes <NUM> may be provided. The spider shaft holes <NUM> may be spaced apart from each other and may be arranged around the first axis <NUM>. For example, spider shaft holes <NUM> may be disposed along axes that may be disposed substantially perpendicular to the first axis <NUM>.

The second side gear <NUM> may be disposed on the output shaft <NUM>. For example, the second side gear <NUM> may be disposed around the first axis <NUM> and may have a center bore that may receive the output shaft <NUM>. The center bore may include a spline that may receive and engage a corresponding spline on the output shaft <NUM>. As such, the second side gear <NUM> may not rotate about the first axis <NUM> with respect to the output shaft <NUM>.

Referring to <FIG> and <FIG>, the spider <NUM> may be fixedly positioned with respect to the case <NUM> and may be rotatably disposed on the drive pinion assembly. The spider <NUM> may or may not engage the drive pinion assembly <NUM>, <NUM>', <NUM>", <NUM>‴ as will be discussed in more detail below. The spider <NUM> may be spaced apart from and may not engage the output shaft <NUM>. As such, the spider <NUM> may be rotatable with respect to the output shaft <NUM>. In at least one configuration, spider <NUM> may include an annular spider body <NUM>, an annular spider flange <NUM>, a spider hole <NUM>, and one or more spider shafts <NUM>.

The annular spider body <NUM> may be axially positioned between the input shaft <NUM> and the drive pinion assembly <NUM>, <NUM>', <NUM>", <NUM>"'. The annular spider body <NUM> may at least partially define the spider hole <NUM>.

The annular spider flange <NUM> may extend from the annular spider body <NUM> in a direction that may extend away from the input shaft <NUM>. The annular spider flange <NUM> may at least partially define the spider hole <NUM> and may support the drive pinion assembly or a stabilizer bearing <NUM> that in turn may support a drive pinion assembly as is best shown in <FIG> and <FIG>.

Referring to <FIG>, one or more spider shafts <NUM> may extend from the annular spider body <NUM>. In the configuration shown, three spider shafts <NUM> are provided; however, it is contemplated that a greater or lesser number of spider shafts <NUM> may be provided in one or more embodiments. The spider shafts <NUM> may be integrally formed with the annular spider body <NUM> or may be provided as separate components that are fixed to the annular spider body <NUM>. Each spider shaft <NUM> may extend from the annular spider body <NUM> in a direction that extends away from the first axis <NUM> and away from the spider hole <NUM>. For example, each spider shaft <NUM> may extend along a spider shaft axis that may be disposed substantially perpendicular to the first axis <NUM>. In addition, an end of each spider shaft <NUM> may be received in a corresponding spider shaft hole <NUM> of the case <NUM>. The spider shafts <NUM> may have a generally cylindrical configuration.

Referring to <FIG> and <FIG>, a pinion gear <NUM> may be rotatably disposed on a corresponding spider shaft <NUM>. Each pinion gear <NUM> may have teeth that may mesh with teeth on the side gear <NUM>, <NUM>", <NUM>‴ and the second side gear <NUM>.

Referring to <FIG>, the thrust bearing <NUM> may be disposed between the case <NUM> and the second side gear <NUM>. The thrust bearing <NUM> may rotatably support the second side gear <NUM> with respect to the first case portion <NUM>.

Referring to <FIG> and <FIG>, an optional stabilizer bearing <NUM> may be provided. The stabilizer bearing <NUM> may rotatably support the spider <NUM>. The stabilizer bearing <NUM> may be received in the annular spider flange <NUM> and may receive the drive pinion body <NUM>", <NUM>‴. The stabilizer bearing <NUM> may help limit or inhibit deflection of the output shaft <NUM> with respect to the first axis <NUM>, which may also help maintain alignment, improve stability, and reduce vibration.

Referring to <FIG>, the differential assembly <NUM> may be disposed in the center portion <NUM> of the housing assembly <NUM>. The differential assembly <NUM> may transmit torque to the vehicle traction wheel assemblies and permit the traction wheel assemblies to rotate at different velocities. An abbreviated discussion of the operation of the differential assembly <NUM> follows with reference to <FIG> and <FIG>, beginning with the input yoke <NUM> shown in <FIG>.

The input yoke <NUM> may be coupled to a vehicle drivetrain component, such as a drive shaft, that may be coupled to an output of a vehicle transmission or transfer case, which in turn may receive torque from a vehicle power source, such as an engine or motor. Alternatively, the input yoke <NUM> may be operatively connected to an output of another axle assembly. The input yoke <NUM> may be operatively connected to the input shaft <NUM>, which in turn may be operatively connected to the drive pinion assembly <NUM>, <NUM>', <NUM>", <NUM>'". The drive pinion assembly <NUM>, <NUM>', <NUM>", <NUM>‴ may provide torque to the ring gear <NUM> of the differential assembly <NUM>. The differential assembly <NUM> may be operatively connected to the axle shafts <NUM> and may permit the axle shaft <NUM> to rotate at different rotational speeds in a manner known by those skilled in the art. As such, the differential assembly <NUM> may receive torque via the ring gear <NUM> and provide torque to the axle shafts <NUM>.

Referring to <FIG> and <FIG>, the axle shafts <NUM> may transmit torque from the differential assembly <NUM> to corresponding traction wheel assemblies. For example, two axle shafts <NUM> may be provided such that each axle shaft <NUM> extends through a different arm portion <NUM> of axle housing <NUM>. The axle shafts <NUM> may extend along and may be rotated about the second axis <NUM> by the differential assembly <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 end assembly that may have a wheel hub that may support a wheel. As shown in <FIG>, an axle flange <NUM> may be disposed proximate the second end of the axle shaft <NUM> and may facilitate coupling of the axle shaft <NUM> to the wheel hub.

The drive pinion assembly configurations described above may allow an axle assembly to be configured without a preload nut that is disposed on a drive pinion between the side gear and a roller bearing assembly that rotatably supports the drive pinion. This may allow the length of the drive pinion to be reduced, which in turn may allow the differential carrier standout or axial length of the differential carrier to be reduced, which may reduce cost and weight and provide a smaller package space. In addition, the drive pinion assembly configurations may allow a drive pinion body to be forged to a near-net or near-final shape and allow a forged side gear to be provided to increase strength and reduce fabrication costs. Moreover, such configurations may also help reduce noise, vibration, and harshness characteristics of the axle assembly when the interaxle differential unit and drive pinion are under dynamic loading that result from articulation of the suspension system that couples the axle assembly to a vehicle chassis.

Claim 1:
An axle assembly (<NUM>) comprising:
a drive pinion assembly (<NUM>‴) that includes:
a drive pinion body (<NUM>‴) having a first end portion (<NUM>), a second end portion (<NUM>) disposed opposite the first end portion (<NUM>), and a flange (<NUM>) that extends away from an axis (<NUM>), the drive pinion body (<NUM>‴) being rotatably supportable by a roller bearing assembly (<NUM>);
a pinion gear (<NUM>, <NUM>') that is fixedly disposed on the first end portion (<NUM>), wherein the pinion gear (<NUM>, <NUM>') has a pinion gear hole (<NUM>) that receives the drive pinion body (<NUM>‴); and
a side gear (<NUM>") that is fixedly disposed on the second end portion (<NUM>), wherein the side gear (<NUM>") has a side gear hole (<NUM>) that receives the drive pinion body (<NUM>‴) and a side gear spline (<NUM>) that is disposed in the side gear hole (<NUM>) and that mates with a second spline (<NUM>) that is disposed on the drive pinion body (<NUM>"'), characterized in that the flange (<NUM>) is received in the side gear hole (<NUM>) and inhibits axial movement of the side gear (<NUM>") away from the pinion gear (<NUM>, <NUM>').