DIFFERENTIAL ASSEMBLY WITH A MOUNTING FLANGE CAVITY
TECHNICAL FIELD
[1] This disclosure relates to a differential assembly that may have a case that has a
cavity in a mounting flange.
BACKGROUND
[2] A differential assembly is disclosed in U.S. Patent No. 9,410,605.
SUMMARY
[3] In at least one embodiment, a differential assembly is provided. The differential
assembly may include a case, a spider, and a retainer pin. The case may have a first case portion and a second case portion. The first case portion may have a first cavity, an outer surface, a spider shaft hole, and an end surface. The outer surface may be disposed around the first cavity. The spider shaft hole may extend from the outer surface to the first cavity. The end surface may be disposed at an end of the first case portion and may extend from the outer surface to the first cavity. The second case portion may be mounted to the end surface. The spider may have a primary spider shaft and a secondary spider shaft. The primary spider shaft may be mounted to the first case portion. The secondary spider shaft may be received in the spider shaft hole and may extend between the spider shaft hole and the primary spider shaft. The primary spider shaft and the secondary spider shaft may not engage the second case portion. The retainer pin may couple the secondary spider shaft to the first case portion and may not engage the second case portion.
[4] In at least one embodiment, a differential assembly is provided. The differential
, assembly may include a case and a ring gear. The case may be rotatable about an axis and may include a first case portion and a second case portion. The first case portion may have a spider receiving portion and a mounting flange. The spider receiving portion may have a first cavity and an outer surface that may extend around the first cavity. The mounting flange may extend away from the axis and may extend from the spider receiving portion. The mounting flange may have a

mounting flange cavity. The mounting flange cavity may be disposed inside the mounting flange and may extend further away from the axis than the first cavity. The second case portion may be disposed on the first case portion. The ring gear may be mounted on the mounting flange and may extend around the spider receiving portion.
BRIEF DESCRIPTION OF THE DRAWINGS
[S] Figure 1 is a perspective view of an axle assembly having a differential carrier.
[6] Figure 2 is a section view Of a portion of the axle assembly along section line 2-2.
[7] Figure 3 is a perspective view of a differential assembly of the axle assembly.
[8] Figure 4 is an exploded view of the differential assembly.
[9] Figures 5 and 6 are perspective views of a first case portion of the differential
assembly.
[10] Figure 7 is a section view of the first case portion along section line 7-7.
[11] Figure 8 is a section view of the first case portion along section line 8-8.
[12] Figure 9 is a perspective view of the sectioned first case portion of Figure 9.
DETAILED DESCRIPTION
[13] 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.

[14] Referring to Figure 1, an example of an axle assembly 10 is shown. The axle
assembly 10 may be provided with a motor 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 motor vehicle may include a trailer for transporting cargo in one or more embodiments.
[IS] The axle assembly 10 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 10 may be provided with the vehicle. For example, the axle assembly 10 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. Thus, the axle assembly 10 may be provided at any suitable location on a vehicle. As is best shown with reference to Figures 1 and 2, the axle assembly 10 may include a housing assembly 20, a differentia! assembly 22, and at least one axle shaft 24.
[16] Referring to Figure 1, the housing assembly 20 may receive various components of
the axle assembly 10. In addition, the housing assembly 20 may facilitate mounting of the axle assembly 10 to the vehicle. The housing assembly 20 may include an axle housing 30 and a differential carrier 32.
[17] The axle housing 30 may receive and support the axle shafts 24. In at least one
embodiment, the axle housing 30 may include a center portion 40 and at least one arm portion 42.
[18] The center portion 40 may be disposed proximate the center of the axle housing 30.
The center portion 40 may define a cavity that may receive the differential assembly 22. As is best shown in Figure 2, a lower region of the center portion 40 may at least partially define a sump portion 50 that may contain lubricant 52. Splashed lubricant may flow down the sides of the center portion 40 and may flow over internal components of the axle assembly 10 and gather in the sump portion 50.
[19] The lubricant 52, which may be a liquid such as oil, may lubricate components of the
axle assembly 10, such as the differential assembly 22 and various bearings. In Figure 2, the level of

the lubricant 52 in the sump portion 50 is represented by the dashed lines. The lubricant levels are merely exemplary and may be higher or lower than what is depicted.
[20] Referring to Figure 1, center portion 40 may also include a carrier mounting surface
54. The carrier mounting surface 54 may face toward and may engage the differential carrier 32. The carrier mounting surface 54 may facilitate mounting of the differential carrier 32 to the axle housing 30. For example, the carrier mounting surface 54 may have a set of holes that may be aligned with corresponding holes on the differential carrier 32. Each hole may receive a fastener, such as a bolt, that may couple the differential carrier 32 to the axle housing 30.
[21] Referring to Figure 1, one or more arm portions 42 may extend from the center
portion 40. For example, two arm portions 42 may extend in opposite directions from the center portion 40 and away from the differential assembly 22. The arm portions 42 may have substantially similar configurations. For example, the arm portions 42 may each have a hollow configuration or tubular configuration that may extend around the corresponding axle shaft 24 and may help separate or isolate the axle shaft 24 from the surrounding environment. An arm portion 42 or a portion thereof may be integrally formed with the center portion 40. Alternatively, an arm portion 42 may be separate from the center portion 40. In such a configuration, each arm portion 42 may be attached to the center portion 40 in any suitable manner, such as by welding or with one or more fasteners. Each arm portion 42 may define an arm cavity that may receive a corresponding axle shaft 24. The arm portion 42 and arm cavity may be disposed above the sump portion 50 in one or more embodiments.
[22] Referring to Figures 1 and 2, the differential carrier 32, which may also be called a
carrier housing, may be mounted to the center portion 40 of the axle housing 30. The differential carrier 32 may support components of the differential assembly 22. In at least one embodiment, the differential carrier 32 may have a flange portion 60, which is best shown in Figure 1, and one or more bearing supports 62, which are best shown in Figure 2.
[23] Referring to Figure 1, the flange portion 60 may facilitate mounting of the differential
carrier 32 to the axle housing 30. For example, the flange portion 60 may be disposed proximate and

may engage the carrier mounting surface 54 of the axle housing 30 and may have a set of holes that may receive fasteners as previously discussed.
[24] Referring to Figure 2, the bearing support 62 may receive a roller bearing assembly
64 that may rotatably support the differential assembly 22. In Figure 2, two bearing supports 62 are shown that are located inside the center portion 40 proximate opposite sides of the differential assembly 22. A bearing support 62 may include a pair of legs that extend from the differential carrier 32. A bearing cap may be mounted to the legs and may arch over a roller bearing assembly 64. The bearing support 62 and bearing cap may cooperate to extend around, receive, and secure the roller bearing assembly 64.
[25] Referring to Figure 2, the differential assembly 22 may be disposed in the center
portion 40 of the housing assembly 20. The differential assembly 22 may transmit torque to the vehicle traction wheel assemblies and permit the traction wheel assemblies to rotate at different velocities. An input shaft 70 is shown in Figure 1 to facilitate an abbreviated discussion of the operation of the axle assembly 10 and the differential assembly 22.
[26] The input shaft 70 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 shaft 70 may be operatively connected to an output of another axle assembly. The input shaft 70 may be rotatably supported by one or more roller bearings that may be disposed on the differential carrier 32 and may be operatively connected to a drive pinion or integrally formed with the drive pinion. The drive pinion may provide torque to a ring gear 72 that may be provided with the differential assembly 22. The ring gear may rotate about an axis 74 and may splash lubricant 52 that accumulates in the sump portion 50 as it rotates. The ring gear 72 may be operatively connected to the axle shafts 24. As such, the differential assembly 22 may receive torque via the ring gear 72 and provide torque to the axle shafts 24.
[27] Referring to Figures 2-4, an example of a differential assembly 22 is shown in more
detail. In addition to the ring gear 72, the differential assembly 22 may include a case 76, a first gear 78, a second gear 80, a spider 82, at least one pinion gear 84, and one or more retainer pins 86.

[28J The case 76 may be configured to receive components of the differential assembly 22.
In addition, the case 76 may be configured to rotate about the axis 74. In at least one embodiment, the case 76 may include a first case portion 90 and a second case portion 92 that may cooperate to at least partially define a cavity. The cavity may at least partially receive the first gear 78, second gear 80, spider 82, and pinion gear(s) 84.
[29] Referring to Figures 3-9, an example of a first case portion 90 is shown. As is best
shown beginning with Figures 3-5, the first case portion 90 may include a first bearing portion 100, a mounting flange 102, a spider receiving portion 104, a first cavity 106, one or more step surfaces 108, and one or more retainer pin openings 110.
[30] Referring to Figures 4 and 6, the first bearing portion 100 may extend around the axis
74 and may extend around and may at least partially define a first hole 120. As is best shown in Figure 2, the first bearing portion 100 may be disposed proximate and may engage a roller bearing assembly 64 that may rotatably support the first case portion 90.
[31] Referring to Figures 2 and 6, the mounting flange 102 may be disposed between the
first bearing portion 100 and the spider receiving portion 104. The mounting flange 102 may extend away from the axis 74 and may extend further away from the axis 74 than the first bearing portion 100 and the spider receiving portion 104. As is best shown with reference to Figures 5 and 7-9, the mounting flange 102 may include a first mounting flange wall 140, a second mounting flange wall 142, amounting flange cavity 144, an inner hub 146, a set of ring gear, mounting bosses 148,asetof fastener openings 150, and a set of ribs 152.
[32] Referring to Figure 2, the first mounting flange wall 140 may extend from the spider
receiving portion 104 to an outside circumference of the mounting flange 102. The first mounting flange wall 140 may be disposed substantially perpendicular to the axis 74 in one or more embodiments. Referring to Figures 2 and 5, the first mounting flange wall 140 may have a first mounting flange surface 160. The first mounting flange surface 160 may face toward and may engage the ring gear 72. The fastener openings 150 may extend from the first mounting flange surface 160 through the first mounting flange wall 140 as will be discussed in more detail below.

[33] Referring to Figures 2 and 5, the second mounting flange wal! 142 may be disposed
opposite the first mounting flange wall 140. For example, the second mounting flange wall 142 may extend from the first bearing portion 100 in a direction that extends away from the axis 74 and toward the first mounting flange wall 140. The second mounting flange wall 142 may extend to the first mounting flange wall 140. More specifically, an end of the second mounting flange wall 142 may intersect or end at a side of the first mounting flange wall 140 that is disposed opposite the first mounting flange surface 160. As is best shown in Figure 2, the first mounting flange wall 140 may be spaced apart from and may not engage the second mounting flange wal! 142 between this end of the second mounting flange wall 142 and the axis 74, thereby cooperating to define at least a portion of the mounting flange cavity 144. Optionally, one or more lubricant openings may extend through the second mounting flange wall 142 to facilitate the flow of lubricant into the case 76 to lubricate internal differential components.
[34] Referring to Figures 2 and 6, the second mounting flange wall 142 may have a second
mounting flange surface 170. The second mounting flange surface 170 may be an exterior surface of the second mounting flange wall 142 that may be disposed opposite and may face away from the first mounting flange surface 160. The second mounting flange surface 170 may be provided with a smooth arcuate contour and without protrusions such as reinforcement ribs and seams. For instance, the second mounting flange surface 170 may be substantially smooth arcuate surface that may extend along an arc or continuous curve between the first bearing portion 100 and the first mounting flange wall 140. Such a configuration may help reduce aerodynamic drag and lubricant drag on the differential assembly 22 as the differential assembly 22 rotates inside the housing assembly 20 and through lubricant in the sump portion 50. Reduced drag on the differential assembly 22 may help improve operating efficiency of the axle assembly 10 and may help reduce vehicle fuel consumption.
[35] Referring to Figure 2, a coating layer 172 may optionally be provided on at least a
portion of the second mounting flange surface 170. The coating layer 172 may help further reduce friction or frictional drag forces on the differential assembly 22. The coating layer 172 may be of any suitable type. For example, the coating layer 172 may be a "nonstick" coating such as polytetrafluoroethylenc.

[36] Referring to Figure 2, the mounting flange cavity 144 may be disposed inside the
mounting flange 102 between the first mounting flange wall 140 and the second mounting flange wall 142. The mounting flange cavity 144 may allow the mounting flange 102 to be provided with a substantially hollow configuration that may help reduce weight. The mounting flange cavity 144 may extend further away from the axis 74 than the spider receiving portion 104. For example, the mounting flange cavity 144 may generally extend from the axis 74 to the location where the second mounting flange wall 142 intersects the first mounting flange wall 140.
[37] Referring to Figures 2 and 5, the inner hub 146 may be disposed in the mounting
flange cavity 144. The inner hub 146 may be configured as a ring that may extend continuously around the axis 74. In addition, the inner hub 146 may be disposed opposite and may extend away from the first bearing portion 100.
[38] Referring to Figures 7-9, the set of ring gear mounting bosses 148 may be arranged
around the axis 74. The ring gear mounting bosses 148 may be spaced apart from each other and may extend in an axial direction from the first mounting flange wall 140 to the second mounting flange wall 142. In addition, the ring gear mounting bosses 148 may extend in a radial direction from the location where the first mounting flange wall 140 intersects the second mounting flange wall 142 toward the axis 74. The ring gear mounting bosses 148 may be spaced apart from the axis 74 and may not extend to the axis 74 or the inner hub 146. As such, the mounting flange cavity 144 may extend between adjacent ring gear mounting bosses 148 and may be at least partially disposed between an end of each ring gear mounting boss 148 and the axis 74. It is also contemplated that the mounting flange cavity 144 may not extend between one or more adjacent ring gear mounting bosses 148. For instance, the mounting flange cavity 144 may not extend between some or all of the ring gear mounting bosses 148 in one or more embodiments.
[39] The set of fastener openings 150 may extend at least partially through the mounting
flanges 102. For example, each fastener opening 150 may extend from the first mounting flange surface 160 to the second mounting flange surface 170 and may extend through the first mounting flange wall 140, a ring gear mounting boss 148, and the second mounting flange wall 142.

[40] Referring to Figures 2 and 4 each fastener opening 150 may receive a fastener 180
that may couple or attach of the ring gear 72 to the mounting flange 102. The fastener 180 may be of any suitable type. For instance, the fastener 180 may be a threaded fastener, such as a bolt that may have a head 182. Each fastener 180 may extend through a hole in the ring gear 72 and partially through a corresponding fastener opening 150. As is best shown in Figure 2, the fastener 180 may be oriented such that the head 182 of the fastener 180 may be disposed proximate and may engage the ring gear 72 while an end of the fastener 180 that is disposed opposite the head 182 may be disposed inside the fastener opening 150 and may not protrude through the second mounting flange surface 170. As is best shown in Figure 3, the heads 182 of the fasteners 180 may be arranged around an outer surface of the spider receiving portion 104. Such a configuration may help reduce drag forces that may occur when the fastener 180 protrudes out of the second mounting flange wall 142 and into the sump portion 50 as the differential assembly 22 rotates about the axis 74.
[41] Referring to Figures 7-9, the set of ribs 152 may be disposed inside the mounting
flange 102 in the mounting flange cavity 144. The ribs 152 may help the mounting flange 102 withstand load forces that may be incurred during operation. The ribs 152 may extend in an axial direction between the first mounting flange wall 140 and the second mounting flange wall 142. The ribs 152 may also extend in a radial direction from the inner hub 146 to a corresponding ring gear mounting boss 148 or member of the set of ring gear mounting bosses 148.
[42] In at least one embodiment, the ribs 152 may be substantially linear and may extend
along a radius with respect to the axis 74. In addition, each rib 152 may extend from the inner hub 146 to an end of a ring gear mounting boss 148 that may be disposed closest to the axis 74 or closer to the axis 74 than the fastener openings 150. The ribs 152 may be spaced apart from each other and may not engage each other.
[43] The ribs 152 may extend to some of the ring gear mounting bosses 148 or all of the
ring gear mounting bosses 148. For example, the ribs 152 may be provided in an alternating pattern around the axis 74 such that a rib 152 extends to every other ring gear mounting boss 148. In such a configuration, a rib 152 may extend to a ring gear mounting boss 148 but another rib 152 may not extend to a ring gear mounting boss 148 that is disposed adjacent to the ring gear mounting boss 148 from which the rib 152 extends. The number of ribs 152 may be varied to provide a desired

stiffness. For instance, more ribs 152 may be provided to increase the stiffness of the mounting
flange 102.
[44] Referring to Figures 2 and 3, the spider receiving portion 104 may extend from the
mounting flange 102 toward the second case portion 92. As is best shown in Figure 5, the spider receiving portion 104 may extend around and may at least partially define the first cavity 106. In at least one embodiment, the spider receiving portion 104 may have an end surface 200, an outer surface 202, and a set of spider shaft holes 204.
[45] Referring to Figures 2 and 5, the end surface 200 may be disposed at an end of the
first case portion 90 that may be disposed opposite the first bearing portion 100. For example, the end surface 200 may be disposed proximate and may engage the second case portion 92. As is best shown with reference to Figures 4 and 5, the end surface 200 may have a plurality of fastener holes 210 that may receive fasteners 212 that may couple the second case portion 92 to the first case portion 90. The end surface 200 may extend around the axis 74 and may extend from the first cavity 106 to the outer surface 202.
[46] The outer surface 202 may be an exterior surface of the spider receiving portion 104.
The outer surface 202 may extend around the axis 74 and at least a portion of the first cavity 106. The outer surface 202 may face away from the first cavity 106.
[47] Referring to Figure 5, a set of spider shaft holes 204 may be provided in the spider
receiving portion 104. A spider shaft hole 204 may receive a spider shaft of the spider 82 as will be discussed in more detail below. In the configuration shown, four spider shaft holes 204 are provided; however, it is contemplated that a greater or lesser number of spider shaft holes 204 may be provided in various embodiments. The spider shaft holes 204 may be spaced apart from each other and may be arranged around the axis 74. For example, spider shaft holes 204 may be disposed along axes that may be disposed substantially perpendicular to the axis 74. The spider shaft holes 204 may be through holes that may be completely defined in the first case portion 90. For example, spider shaft holes 204 may extend from the first cavity 106 to the outer surface 202.

[48] The first cavity 106 may be disposed in the first case portion 90. The first cavity 106
may receive the first gear 78, spider 82, and at least a portion of a pinion gear 84. In addition, the first cavity 106 may extend from the end surface 200 to the mounting flange cavity 144.
[49] Referring to Figures 2 and 5, one or more step surfaces 108 may be provided with the
spider receiving portion 104. In the configuration shown, four step surfaces 108 are provided; however, it is contemplated that a greater or lesser number of step surfaces 108 may be provided in one or more embodiments. The step surfaces 108 may extend from or may be disposed proximate to the outer surface 202. In addition, the step surfaces 108 may be disposed substantially perpendicular to the axis 74 in one or more embodiments. Each step surface 108 may be aligned with a spider shaft hole 204.
[SO] Referring to Figures 5 and 6, one or more retainer pin openings 110 may extend
through the first case portion 90. In at least one embodiment,, the retainer pin openings 110 may extend through the first case portion 90 from a step surface 108 to the second mounting flange surface 170. As is best shown in Figure 2, a retainer pin opening 110 may be configured to receive a retainer pin 86 to couple the spider 82 to the case 76 as will be discussed in more detail below. The retainer pin openings 110 may extend substantially parallel to the axis 74. As is best shown in Figures 7 and 8, a retainer pin openings 110 may extend through a rib 152 and may be radially positioned between the axis 74 and a ring gear mounting boss 148.
[51] Referring to Figures 2-4, the second case portion 92 may be mounted to and may not
rotate with respect to the first case portion 90. For instance, the second case portion 92 may be assembled to the first case portion 90 and the second case portion 92 in any suitable manner, such as by using one or more fasteners 212 that may extend through holes in the second case portion 92, by press fitting (e.g. an interference fit), a transition fit, or the like. These various assembly techniques may be employed due to the positioning of the interface between the first case portion 90 and the second case portion 92 where lower load forces or bending moments are incurred. In at least one embodiment, the second case portion 92 may include a second bearing portion 220, a second mounting portion 222, and a second cavity 224.

[52] The second bearing portion 220 may extend around the axis 74 and may extend
around the second cavity 224. As is best shown in Figure 2, a roller bearing assembly 64 that rotatably supports the second case portion 92 may be disposed on the second bearing portion 220.
[53] The second mounting portion 222 may extend from the second bearing portion 220
toward the first case portion 90. The second mounting portion 222 may also extend outwardly from the second bearing portion 220 and away from the axis 74. As is best shown in Figure 2, the second mounting portion 222 may extend around and may at least partially define the second cavity 224.
[54] Referring to Figure 2, the second cavity 224 may be disposed inside the second case
portion 92. The second cavity 224 may at least partially receive the second gear 80 and an axle shaft 24... The second cavity 224 may extend from an end of the second mounting portion 222 through the second case portion 92.
[55] Referring to Figures 2 and 4, the first gear 78 may be disposed in the first case portion
90. For example, the first gear 78 may be at least partially disposed in the first hole 120 and the mounting flange cavity 144 and may be configured to rotate about the axis 74. As is best shown in Figure 4, the first gear 78 may include a first gear hole 230 and a gear portion 232.
[56] The first gear hole 230 may be disposed along the axis 74. The first gear hole 230
may be configured to receive the first axle shaft 24. In addition, the first gear 78 may rotate with the first axle shaft 24. For example, the first gear hole 230 may have a spline that may mate with a corresponding spline on the first axle shaft 24 such that the first gear 78 may not rotate with respect to the first axle shaft 24.
[57] The gear portion 232 may face toward and may be spaced apart from the spider 82.
The gear portion 232 may have a set of teeth that may be arranged around the axis 74 and that may mate with teeth on one or more pinion gears 84. A thrust washer 240 or bearing may be disposed between the gear portion 232 and the first case portion 90.
[58] The second gear 80 may be disposed in the first case portion 90 and the second case
portion 92. For example, the second gear 80 may be at least partially disposed in the first cavity 106 and the second cavity 224 and may be configured to rotate about the axis 74. The second gear 80

may be spaced apart from the first gear 78 and may have a similar or identical configuration as the first gear 78. In at least one embodiment, the second gear 80 may include a second gear hole 250 and a gear portion 252.
[59] The second gear hole 250 may be disposed along the axis 74. The second gear hole
250 may be configured to receive the second axle shaft 24. In at least one embodiment, the second gear 80 may rotate with the first axle shaft 24. For example, the second gear hole 250 may have a spline that may mate with a corresponding spline on the second axle shaft 24 such that the second gear 80 may not rotate with respect to the second axle shaft 24.
[60] The gear portion 252 may face toward and may be spaced apart from the spider 82.
The gear portion 252 may have a set of teeth that may be arranged around the axis 74 and that may mate with teeth on one or more pinion gears 84. A thrust washer 240 or bearing may be disposed between the gear portion 252 and the second case portion 92.
[61] Referring to Figures 2 and 4, the spider 82 may rotate about the axis 74 with the case
76. In at least one embodiment, the spider 82 may include a primary spider shaft 260 and at least one secondary spider shaft 262.
[62] The primary spider shaft 260 may be mounted to the first case portion 90. For
example, the primary spider shaft 260 may have opposing ends that may be received in corresponding spider shaft holes 204 of the first case portion 90. As such, the primary spider shaft 260 may extend across the first cavity 106 and may extend through the axis 74. The primary spider shaft 260 may be disposed along a primary spider shaft axis 270. The primary spider shaft axis 270 may intersect and may be disposed substantially perpendicular to the axis 74. As is best shown in Figure 4> the primary spider shaft 260 may have a generally cylindrical configuration and may include one or more notches 272.
[63] One or more notches 272 may be disposed proximate the center of the primary spider
shaft 260. In the configuration shown in Figure 4, two notches 272 are provided that are disposed opposite each other and extend inwardly toward the axis 74. A notch 272 may receive and facilitate positioning of a secondary spider shaft 262 with respect to the primary spider shaft 260.

[64] Referring to Figures 2 and 4, one. or more secondary spider shafts 262 may be
mounted to the first case portion 90. The secondary spider shaft 262 may extend from a spider shaft hole 204 to the primary spider shaft 260. For example, the secondary spider shaft 262 may have a first end that may be received in the notch 272 of the primary spider shaft 260 and a second end that may be disposed opposite the first end and may be received in a corresponding spider shaft hole 204. The secondary spider shaft 262 may be disposed along a secondary spider shaft axis 280. The secondary spider shaft axis 280 may intersect and may be disposed substantially perpendicular to the axis 74 and the primary spider shaft axis 270. In addition, the primary spider shaft axis 270 and secondary spider shaft axis 280 may be substantially coplanar or disposed in a common plane. In the configuration shown in Figure 4, two secondary spider shafts 262 are provided that are disposed on opposite sides of the primary spider shaft 260 and are coaxially disposed along the secondary spider shaft axis 280. The secondary spider shafts 262 may have common or substantially identical configurations that may include a tapered end 282.
[65] The tapered end 282 may be disposed proximate the primary spider shaft 260. For
example the tapered end 282 may be received in a notch 272 of the primary spider shaft 260. The secondary spider shaft 262 and its tapered end 282 may not be fixedly attached to the primary spider shaft 260 in one or more embodiments.
[66] A pinion gear 84 may be rotatably disposed on the primary spider shaft 260 and the
secondary spider shafts 262. For instance, two pinion gears 84 may be disposed on the primary spider shaft 260 while a single pinion gear 84 may be disposed on each secondary spider shaft 262. Each pinion gear 84 may be disposed in the cavity of the case 76 and may be retained on a corresponding spider shaft with one or more fasteners 290, such as a washer and/or a thrust bearing. The fastener 290 may engage an inner wall of the first case portion 90. The pinion gears 84 on the primary spider shaft 260 may rotate about the primary spider shaft axis 270. The pinion gear 84 on the secondary spider shaft 262 may rotate about the secondary spider shaft axis 280. Each pinion gear 84 may include a set of teeth that mate with teeth on the first gear 78 and teeth on the second gear 80.
[67] Referring to Figures 2 and 4, one or more retainer pins 86 may be provided to secure
the primary spider shaft 260 and/or the secondary spider shaft 262 to the first case portion 90. A

retainer pin 86 may be received in a retainer pin opening 110 and may extend through a corresponding hoie in a spider shaft.
[68] Referring to Figure 2, the axle shafts 24 may transmit torque from the differential
assembly 22 to corresponding traction wheel assemblies. In Figure 2, two axle shafts 24 are provided such that each axle shaft 24 extends through a different arm cavity. The axle shafts 24 may extend along and may be rotated about the axis 74 by the differential assembly 22. Each axle shaft 24 may have a first end and a second end. The first end may be coupled to the differential assembly 22. 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 Figure 1, an axle flange 300 may be disposed proximate the second end of the axle shaft 24 and may facilitate coupling of the axle shaft 24 to the wheel hub.
[69] The differential assembly described above may allow an axle assembly and a
differential assembly to be provided with reduced weight due to the hollow mounting flange while providing improved stiffness by way of the mounting flange ribs as compared to a comparable design with a solid mounting flange. In addition, the differential assembly may have improved operating efficiency due to reduced drag forces on the case. In addition, the differential assembly may have improved durability as the spider holes may be completely formed in the first case portion rather than between the first and second case portions, which allows torque to be directly transferred from the first case portion to the spider rather than through a bolted or welded attachment interface between the first and second case portions. In addition, the differential assembly described above relocates the attachment interface between the first case portion and the second case portion away from the spider and closer to a roller bearing assembly disposed opposite the ring gear where lower bending moments are incurred, thereby producing a stiffer case configuration. Such a configuration may allow smaller fasteners to be utilized while withstanding associated load forces. Furthermore, the differential assembly described above may help enable unidirectional assembly of the differential assembly in which the internal components of the differential assembly may be inserted into a portion of the differential case in a common direction, which may allow the orientation of the differential case to be maintained during assembly to improve efficiency and reduce material handling.

[70] 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.

WHAT IS CLAIMED IS:
1. A differential assembly comprising:
a case that includes:
a first case portion that has a first cavity, an outer surface disposed around the first cavity, a spider shaft hole that extends from the outer surface to the first cavity, and an end surface that is disposed at an end of the first case portion and extends from the outer surface to the first cavity; and
a second case portion mounted to the end surface; and a spider that includes:
a primary spider shaft that is mounted to the first case portion and does not engage the second case portion; and
a secondary spider shaft that is received in the spider shaft hole and that extends between the spider shaft hole and the primary spider shaft, wherein the secondary spider shaft does not engage the second case portion; and
a retainer pin that couples the secondary spider shaft to the first case portion and does not engage the second case portion.
2. The differential assembly of claim 1 wherein the first case portion has a retainer pin opening that receives a retainer pin that extends through the secondary spider shaft and does not engage the second case portion.
3. The differential assembly of claim 2 wherein the case is rotatable about an axis and the first case portion has a step surface that extends from the outer surface, wherein the step surface is axially positioned between the end surface and the spider shaft hole and extends radially with respect to the axis, wherein the retainer pin opening extends from the step surface toward the spider shaft hole.
4. The differential assembly of claim 3 wherein the first case portion has a mounting flange that extends away from the axis and from the outer surface, wherein a ring gear is mounted on the mounting flange.

5. The differential assembly of claim 4 wherein the retainer pin opening extends completely through the mounting flange.
6. The differential assembly of claim 5 wherein the mounting flange has fastener openings that are arranged around the axis, wherein each fastener opening receives a fastener that extends through the ring gear to couple the ring gear to the mounting flange, wherein heads of the fasteners are arranged around the outer surface.
7. The differential assembly of claim 6 wherein the retainer pin opening is disposed closer to the axis than the fastener openings.
8. The differential assembly of claim 6 wherein the mounting flange has a first mounting flange surface that faces toward the end surface and upon which the ring gear is disposed and a second mounting flange surface that is disposed opposite the first mounting flange surface, wherein the fastener openings extend from the first mounting flange surface to the second mounting flange surface and the fasteners do not protrude from the second mounting flange surface.
9. The differential assembly of claim 8 wherein the second mounting flange surface is an arcuate surface that is provided without ribs.
10. The differential assembly of claim 8 further comprising a coating layer that is disposed on at least a portion of the second mounting flange surface that reduces frictional drag on the case.
11. A differential assembly comprising:
' a case that is rotatable about an axis and includes:
a first case portion that has:
a spider receiving portion that has a first cavity and an outer surface that extends around the first cavity; and

a mounting flange that extends away from the axis and extends from the spider receiving portion, the mounting flange having a mounting flange cavity disposed inside the mounting flange, the mounting flange cavity extending further away from the axis than the first cavity; and
a second case portion disposed on the first case portion; and a ring gear that is mounted on the mounting flange and extends around the spider receiving portion.
12. The differential assembly of claim 11 wherein the mounting flange has a first mounting flange wall that engages the ring gear and that extends outwardly from the spider receiving portion in a direction that extends away from the axis, a second mounting flange wall that is disposed opposite the first mounting flange wall, a set of ring gear mounting bosses that are disposed in the mounting flange cavity and that extend from the first mounting flange wall to the second mounting flange wall.
13. The differential assembly of claim 12 wherein the ring gear mounting bosses are spaced apart from each other and a fastener opening extends through each ring gear mounting boss, the fastener opening receiving a fastener that couples the ring gear to the mounting flange.
14. The differential assembly of claim 12 wherein the first case portion has an inner hub that is disposed in the mounting flange cavity and is spaced apart from the ring gear mounting bosses.
15. The differential assembly of claim 14 further comprising a rib that extends from the inner hub to a ring gear mounting boss.
16. The differential assembly of claim 15 wherein the mounting flange has a fastener opening and the rib extends in a radial direction from the inner hub toward the fastener opening.

17. The differential assembly of claim 15 wherein the first case portion has a retainer pin opening that receives a retainer pin that extends through a secondary spider shaft.
18. The differential assembly of claim 17 wherein the retainer pin opening extends through the rib.
19. The differential assembly of claim 11 wherein the mounting flange has a first mounting flange wail that is disposed adjacent to the ring gear and that extends outwardly from the spider receiving portion in a direction that extends away from the axis, and a second mounting flange wall that is disposed opposite the first mounting flange wall, wherein the mounting flange cavity is disposed between the first mounting flange wall and the second mounting flange wall.
20. The differential assembly of claim 19 wherein a set of ribs extends from the first mounting flange wall to the second mounting flange wall.