AXLE assembly and a shift mechanism

Abstract

A shift mechanism and an axle assembly having a shift mechanism. The shift mechanism comprises an actuator, a detent linkage pin that extends from a detent linkage, a linkage pin and first and second limit pins that extend from a linkage, a shift collar, and a biasing member. The biasing member operatively connects the detent linkage to the linkage and that permits the actuator shaft and the detent linkage to rotate about the actuator axis with respect to the linkage when the shift collar is inhibited from moving along the axis.

Description

[0001]AXLE ASSEMBLY AND A SHIFT MECHANISM CROSS REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. provisional application serial no. 63 / 609,059 filed December 12, 2023, the disclosure of which is hereby incorporated in its entirety by reference herein. TECHNICAL FIELD This relates to an axle assembly comprising a shift mechanism and a shift mechanism. BACKGROUND An axle assembly having a clutch collar is disclosed in U.S. Patent No. 9,719,563. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of an example of an axle assembly. Figure 2 is a section view of the axle assembly along section line 2-2. Figure 3 is an end view of the axle assembly with a cover removed and with an electric motor module and axle housing of the axle assembly omitted for clarity. Figure 4 is a section view of a portion of the axle assembly along section line 4-4 with the electric motor module and drive pinion omitted for clarity. Figure 5 is a perspective view that includes an example of a shift mechanism comprising a shift collar that may be provided with the axle assembly. Figure 6 is an exploded view of a portion of the shift mechanism shown in Figure 5. Figure 7 is a section view of a portion of the axle assembly along section line 7-7 with the electric motor module and drive pinion omitted for clarity and with the shift collar in a first position. Figure 8 is a section view of a portion of the axle assembly in Figure 7 with the shift collar in a first neutral position. Figure 9 is a section view of a portion of the axle assembly in Figure 7 with the shift collar in a second position. Figure 10 is a section view of a portion of the axle assembly in Figure 7 with the shift collar in a second neutral position. Figure 11 is a section view of a portion of the axle assembly in Figure 7 with the shift collar in a third position. Figure 12 is a perspective view of a linkage of the shift mechanism. Figures 13-16 are section views of a portion of the axle assembly illustrating an actuation sequence from the first position to the first neutral position when there is a blocked shift condition with a shift mechanism comprising a biasing member having a first configuration. Figures 17-20 are section views of a portion of the axle assembly illustrating an actuation sequence from the second position to the first neutral position when there is a blocked shift condition with a shift mechanism comprising a biasing member having a first configuration. Figures 21-24 are section views of a portion of the axle assembly illustrating an actuation sequence from the first position to the first neutral position when there is a blocked shift condition with a shift mechanism comprising a biasing member having a second configuration. Figures 25-28 are section views of a portion of the axle assembly illustrating an actuation sequence from the second position to the first neutral position when there is a blocked shift condition with a shift mechanism comprising a biasing member having a second configuration. DETAILED DESCRIPTION As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention. It will also be understood that, although the terms first, second, etc. are, in some instances, used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly a second element could be termed a first element without departing from the scope of the various described embodiments. The first element and the second element are both elements, but they are not the same element. The terminology used in the description of the various described embodiments is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various described embodiments and the appended claims, the singular forms “a” and “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the term “and / or” as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. It will be further understood that the terms “includes,” “including,” “comprises,” and / or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. 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. The axle assembly 10 is configured to provide torque to one or more traction wheel assemblies that may include a tire mounted on a wheel. The wheel may be mounted to a wheel hub that may be rotatable about a wheel axis. One or more axle assemblies may be provided with the vehicle. A single axle assembly is shown in Figures 1 and 2. In some configurations, the axle assembly 10 includes a housing assembly 20, a differential assembly 22, at least one axle shaft 24, an electric motor module 26, and a transmission module 28, a drive pinion 30, a shift mechanism 32, or combinations thereof. Referring to Figure 1, the housing assembly 20 receives various components of the axle assembly 10. In addition, the housing assembly 20 facilitates mounting of the axle assembly 10 to the vehicle. In some configurations, the housing assembly 20 includes an axle housing 40 and a differential carrier 42. The axle housing 40 receives and may support the axle shafts 24. In some configurations, the axle housing 40 includes a center portion 50 and at least one arm portion 52. The center portion 50 may be disposed proximate the center of the axle housing 40. As is best shown in Figure 2, the center portion 50 may define a cavity 54 that may at least partially receive the differential assembly 22. A lower region of the center portion 50 may at least partially define a sump portion 56 that may contain or collect lubricant 58. Lubricant 58 in the sump portion 56 may be splashed by a ring gear 82 of the differential assembly 22 and distributed to lubricate various components that may or may not be received in the housing assembly 20. For instance, some splashed lubricant 58 may lubricate components that are received in the cavity 54 like the differential assembly 22, bearing assemblies that rotatably support the differential assembly 22, a drive pinion 30, and so on, while some splashed lubricant 58 may be routed out of the cavity 54 to lubricate components located outside of the housing assembly 20, such as components associated with the transmission module 28, the shift mechanism 32, or both. Referring to Figure 1, one or more arm portions 52 may extend from the center portion 50. For instance, two arm portions 52 may extend in opposite directions from the center portion 50 and away from the differential assembly 22. The arm portions 52 may comprise similar configurations. For example, the arm portions 52 may each have a hollow tubular configuration that may extend around and may receive a corresponding axle shaft 24 and may help separate or isolate the axle shaft 24 or a portion thereof from the surrounding environment. An arm portion 52 or a portion thereof may or may not be integrally formed with the center portion 50. It is also contemplated that the arm portions 52 may be omitted. Referring primarily to Figure 2, the differential carrier 42 is configured to support the differential assembly 22. For example, the differential carrier 42 may include one or more bearing supports that may support a bearing like a roller bearing assembly that may rotatably support the differential assembly 22. The differential carrier 42 may be mounted to the center portion 50 of the axle housing 40. The differential carrier 42 may also facilitate mounting of the electric motor module 26. In some configurations, the differential carrier 42 includes a mounting flange 60 and / or a bearing support wall 62. The mounting flange 60 facilitates mounting of the electric motor module 26. As an example, the mounting flange 60 may be configured as a ring that may extend around an axis 70. In some configurations, the mounting flange 60 includes a set of fastener holes that may be configured to receive fasteners that may secure the electric motor module 26 to the mounting flange 60. The bearing support wall 62 is configured to support bearings that may rotatably support other components of the axle assembly 10. For example, the bearing support wall 62 may support a bearing that may rotatably support the drive pinion 30, a bearing that may rotatably support a rotor of the electric motor module 26, or both. The bearing support wall 62 may extend in an axial direction away from the axle housing 40 and may extend around the axis 70. The bearing support wall 62 may define a hole that may extend along or around the axis 70 and receive the drive pinion 30 and the bearings that rotatably support the drive pinion 30. The bearing support wall 62 may be integrally formed with the differential carrier 42 or may be a separate component that is fastened to the differential carrier 42. Referring to Figure 2, the differential assembly 22 is about a differential axis 80 and is configured to transmit torque to the axle shafts 24 and wheels. The differential assembly 22 is operatively connected to the axle shafts 24 and may permit the axle shafts 24 to rotate at different rotational speeds in a manner known by those skilled in the art. The differential assembly 22 may be at least partially received in the center portion 50 of the housing assembly 20. The differential assembly 22 may comprise a ring gear 82 that may comprise teeth that mate or mesh with the teeth of a gear portion of the drive pinion 30. Accordingly, the differential assembly 22 may receive torque from the drive pinion 30 via the ring gear 82 and transmit torque to the axle shafts 24. The drive pinion 30 is rotatable about the axis 70. The drive pinion 30 may operatively connect the transmission module 28 to the differential assembly 22. As such, the drive pinion 30 may transmit torque between the differential assembly 22 and the transmission module 28. In some configurations, the drive pinion 30 is rotatably supported inside another component, such as the bearing support wall 62. Referring primarily to Figure 2 and 6, the drive pinion 30 may optionally include or may be coupled to a drive pinion extension 90. The drive pinion extension 90 may effectively increase the axial length of the drive pinion 30. In some configurations, the drive pinion extension 90 is a separate component from the drive pinion 30 and may be coupled to the drive pinion 30 such that the drive pinion extension 90 is rotatable about the axis 70 with the drive pinion 30. In addition, the drive pinion extension 90 may be fixedly positioned with respect to the drive pinion 30 such that the drive pinion extension 90 may not move along the axis 70 with respect to the drive pinion 30. It is also contemplated that the drive pinion extension 90 may be integrally formed with the drive pinion 30. For convenience in reference, the term “drive pinion” is used herein to refer to the drive pinion 30 with or without the drive pinion extension 90. In some configurations, the drive pinion extension 90 extends from a first end 92 to a second end 94 and may include a socket 96 and the spline 98. The socket 96 may extend from the first end 92 and may receive the drive pinion 30. The second end 94 may be received inside and may be rotatably supported by a support bearing 418. The spline 98, if provided, facilitates coupling of the drive pinion extension 90 to a shift collar 310 that may be moveable along the axis 70 as will be discussed in more detail below. Referring to Figure 1, the axle shafts 24 are configured to transmit torque between the differential assembly 22 and corresponding wheel hubs and wheels. Two axle shafts 24 may be provided such that each axle shaft 24 extends through a different arm portion 52 of axle housing 40. The axle shafts 24 may extend along and may be rotatable about an axis, such as the differential axis 80. Each axle shaft 24 may comprise a first end and a second end. The first end may be operatively connected to the differential assembly 22. The second end may be disposed opposite the first end and may be operatively connected to a wheel. Optionally, gear reduction may be provided between an axle shaft 24 and a wheel. Referring to Figure 2, the electric motor module 26, which may also be referred to as an electric motor, is configured to provide torque, such as propulsion torque and regenerative brake torque. In some configurations, the electric motor module 26 is mounted to the differential carrier 42 and is operatively connectable to the differential assembly 22. For instance, the electric motor module 26 may configured to provide torque to the differential assembly 22 via the transmission module 28 and the drive pinion 30 as will be discussed in more detail below. The electric motor module 26 may be primarily or completely disposed outside the differential carrier 42. In addition, the electric motor module 26 may be axially positioned between the axle housing 40 and the transmission module 28. In some configurations, the electric motor module 26 includes a motor housing 100, a coolant jacket 102, a stator 104, a rotor 106, and at least one rotor bearing assembly 108. The electric motor module 26 may also include a motor cover 110. The motor housing 100 may extend between the differential carrier 42 and the motor cover 110. The motor housing 100 may be mounted to the differential carrier 42 and the motor cover 110. For example, the motor housing 100 may extend from the mounting flange 60 of the differential carrier 42 to the motor cover 110. The motor housing 100 may extend around the axis 70 and may define a motor housing cavity 120. The motor housing cavity 120 may be disposed inside the motor housing 100 and may comprise a generally cylindrical configuration. The bearing support wall 62 of the differential carrier 42 may be located inside the motor housing cavity 120. Moreover, the motor housing 100 may extend continuously around and may be spaced apart from the bearing support wall 62. In some configurations, the motor housing 100 comprises an exterior side 122, an interior side 124, a first end surface 126, and a second end surface 128. The exterior side 122 faces away from the axis 70 and may define an exterior or outside surface of the motor housing 100. The interior side 124 is disposed opposite the exterior side 122 and may face toward the axis 70. The interior side 124 may be disposed at a substantially constant radial distance from the axis 70 in one or more configurations. The first end surface 126 is disposed at an end of the motor housing 100 that may face toward the differential carrier 42. For instance, the first end surface 126 may be disposed adjacent to the mounting flange 60 of the differential carrier 42 and may engage or contact the mounting flange 60. The first end surface 126 may extend between the exterior side 122 and the interior side 124. The second end surface 128 may be disposed opposite the first end surface 126. As such, the second end surface 128 may be disposed at an end of the motor housing 100 that may face toward the motor cover 110 and may engage or contact the motor cover 110. The coolant jacket 102 facilitates cooling or heat removal, such cooling of the stator 104. The coolant jacket 102 is received in the motor housing cavity 120 of the motor housing 100 and may engage the interior side 124 of the motor housing 100. The coolant jacket 102 may extend axially (e.g., in a direction along the axis 70) between the differential carrier 42 and the motor cover 110. For example, the coolant jacket 102 may extend axially from the differential carrier 42 to the motor cover 110. In addition, the coolant jacket 102 may extend around the axis 70 and around the stator 104. Accordingly, the stator 104 may be at least partially received in and may be encircled by the coolant jacket 102. The coolant jacket 102 may extend in a radial direction from the stator 104 to the interior side 124 of the motor housing 100. In some configurations, the coolant jacket 102 includes a plurality of channels through which coolant may flow. The stator 104 is received in the motor housing cavity 120. The stator 104 may be fixedly positioned with respect to the coolant jacket 102. For example, the stator 104 may extend around the axis 70 and may include stator windings that may be received inside and may be fixedly positioned with respect to the coolant jacket 102. The rotor 106 extends around and is rotatable about an axis, such as axis 70. In addition, the rotor 106 may extend around and may be supported by the bearing support wall 62. The rotor 106 may be received inside the stator 104, the coolant jacket 102, and the motor housing cavity 120 of the motor housing 100. The rotor 106 may be rotatable about the axis 70 with respect to the differential carrier 42 and the stator 104. In addition, the rotor 106 may be spaced apart from the stator 104 but may be disposed in close proximity to the stator 104. One or more rotor bearing assemblies 108 rotatably support the rotor 106. For example, a rotor bearing assembly 108 may extend around and receive the bearing support wall 62 of the differential carrier 42 and may be received inside of the rotor 106. The rotor 106 may be operatively connected to the drive pinion 30. For instance, a coupling such as a rotor output flange 130 may operatively connect the rotor 106 to the transmission module 28, which in turn may be operatively connectable to the drive pinion 30. The motor cover 110 may be mounted to the motor housing 100 and may be disposed opposite the axle housing 40 and the differential carrier 42. For example, the motor cover 110 may be mounted to the second end surface 128 of the motor housing 100. The motor cover 110 may be spaced apart from and may not engage the differential carrier 42. The motor cover 110 may be provided in various configurations. In some configurations, the motor cover 110 includes a first side 140 and a second side 142. The first side 140 may face toward and may engage the motor housing 100. The second side 142 may be disposed opposite the first side 140. The second side 142 may face away from the motor housing 100. The motor cover 110 may also include a motor cover opening through which the drive pinion 30 may extend. The motor cover 110 may be integrated with the transmission module 28 or may be a separate component. Referring to Figures 2 and 4, the transmission module 28 is configured to transmit torque between the electric motor module 26 and the differential assembly 22. As such, the transmission module 28 may be operatively connectable to the electric motor module 26 and the differential assembly 22. In some configurations, the transmission module 28 includes a transmission housing. The transmission housing may comprise one or more individual housings, such as a first transmission housing 200, a second transmission housing 202. The transmission module 28 comprises a transmission 204. The first transmission housing 200 and the second transmission housing 202 may cooperate to define a transmission housing cavity 206 that may receive the transmission 204. The first transmission housing 200 may be mounted to the electric motor module 26. For instance, the first transmission housing 200 may be mounted to the second side 142 of the motor cover 110. As such, the motor cover 110 may separate the first transmission housing 200 from the motor housing 100. The second transmission housing 202 may be mounted to the first transmission housing 200. For instance, the second transmission housing 202 may be mounted to and may engage or contact a side of the first transmission housing 200 that may face away from the motor cover 110. As such, the first transmission housing 200 may separate the second transmission housing 202 from the motor cover 110. The transmission 204 is operatively connected to the electric motor. In some configurations, the transmission 204 is configured as a countershaft transmission that includes a set of drive pinion gears 210, a first countershaft gear set 212, and optionally a second countershaft gear set 214. The set of drive pinion gears 210 is received in the transmission housing cavity 206 of the transmission housing and may be arranged along the axis 70, such as between the first transmission housing 200 and the second transmission housing 202. The set of drive pinion gears 210 may include a plurality of gears, some or all of which may be selectively coupled to the drive pinion 30. The set of drive pinion gears 210 is spaced apart from the drive pinion 30 and is rotatable about the axis 70. The drive pinion gears may be independently rotatable with respect to each other. In the configuration shown, the set of drive pinion gears 210 includes a first gear 220, a second gear 222, a third gear 224, and a fourth gear 226; however, it is to be understood that a greater or lesser number of gears may be provided. The first gear 220 extends around the axis 70 and may be disposed proximate the first transmission housing 200. In some configurations, the first gear 220 comprises a through hole that may receive the drive pinion 30, an extension of the drive pinion 30 like the drive pinion extension 90, or both. The first gear 220 may comprise a plurality of teeth that may be arranged around and may extend away from the axis 70. The teeth of the first gear 220 may contact and may mate or mesh with teeth of a first countershaft gear that may be provided with the first countershaft gear set 212 and the second countershaft gear set 214 as will be discussed in more detail below. The first gear 220 may be operatively connected to the rotor 106 of the electric motor module 26 such that the rotor 106 and the first gear 220 are rotatable together about the axis 70. For example, the first gear 220 may be fixedly positioned with respect to the rotor 106 or fixedly coupled to the rotor 106 such that the first gear 220 is not rotatable about the axis 70 with respect to the rotor 106. It is contemplated that the first gear 220 may be fixedly mounted to or integrally formed with the rotor output flange 130. As such, the first gear 220 may be continuously connected to the rotor 106 such that the first gear 220 and the rotor 106 may be rotatable together about the axis 70 but may not be rotatable with respect to each other. It is also contemplated that the first gear 220 may be selectively coupled to the drive pinion 30 or drive pinion extension 90, such as with a shift collar. In addition, the first gear 220 may be decoupled from the drive pinion 30 and may be rotatable with respect to the drive pinion 30. As such, a clutch or shift collar 310 may not connect the first gear 220 to the drive pinion 30 or the drive pinion extension 90. The drive pinion extension 90, if provided, may be received inside the first gear 220 and may be spaced apart from the first gear 220. In some configurations, the first gear 220 is axially positioned along the axis 70 between the second gear 222 and the electric motor module 26. The second gear 222 extends around the axis 70. In some configurations, the second gear 222 comprises a through hole that may receive the drive pinion 30, the drive pinion extension 90, or both. The second gear 222 may comprise a plurality of teeth that may be arranged around and may extend away from the axis 70. The teeth of the second gear 222 may contact and may mate or mesh with teeth of a second countershaft gear that may be provided with the first countershaft gear set 212 and the second countershaft gear set 214 as will be discussed in more detail below. As is best shown in Figure 7, the second gear 222 may also comprise inner gear teeth 232 that may extend toward the axis 70 and may be received in the through hole. The second gear 222 may comprise a different diameter than the first gear 220. For example, the second gear 222 may comprise a larger diameter than the first gear 220. In some configurations, the second gear 222 is axially positioned along the axis 70 between the first gear 220 and the third gear 224. The drive pinion 30 or drive pinion extension 90, if provided, may be received inside the second gear 222 and may be spaced apart from the second gear 222 in one or more configurations. The third gear 224 extends around the axis 70. In some configurations, the third gear 224 comprises a through hole that may receive the drive pinion 30, the drive pinion extension 90, or both. The third gear 224 may comprise a plurality of teeth that may be arranged around and may extend away from the axis 70. The teeth of the third gear 224 may contact and may mate or mesh with teeth of a third countershaft gear that may be provided with the first countershaft gear set 212 and the second countershaft gear set 214 as will be discussed in more detail below. As is best shown in Figure 7, the third gear 224 may also comprise inner gear teeth 234 that may extend toward the axis 70 and may be received in the through hole. The third gear 224 may comprise a different diameter than the first gear 220 and the second gear 222. For example, the third gear 224 may comprise a larger diameter than the first gear 220 and the second gear 222. In some configurations, the third gear 224 is axially positioned along the axis 70 between the second gear 222 and the fourth gear 226. The drive pinion 30 or drive pinion extension 90, if provided, may be received inside the third gear 224 and may be spaced apart from the third gear 224 in one or more configurations. The fourth gear 226 extends around the axis 70. In some configurations, the fourth gear 226 may comprise a through hole that may receive the drive pinion 30, the drive pinion extension 90, or both. The fourth gear 226 may comprise a plurality of teeth that may be arranged around and may extend away from the axis 70. The teeth of the fourth gear 226 may contact and may mate or mesh with teeth of a fourth countershaft gear that may be provided with the first countershaft gear set 212 and the second countershaft gear set 214 as will be discussed in more detail below. As is best shown in Figure 7, the fourth gear 226 may also comprise inner gear teeth 236 that may extend toward the axis 70 and may be received in the through hole. The fourth gear 226 may comprise a different diameter than the first gear 220, the second gear 222, and the third gear 224, such as a larger diameter. In some configurations, the fourth gear 226 is axially positioned along the axis 70 farther from the electric motor module 26 than the first gear 220, the second gear 222, and the third gear 224. As such, the fourth gear 226 may be axially positioned proximate or adjacent to a side of the second transmission housing 202 that is disposed opposite the first transmission housing 200. The drive pinion 30 or drive pinion extension 90 may be received inside the fourth gear 226 and may be spaced apart from the fourth gear 226 in one or more configurations. Referring to Figure 4, thrust bearings 240 may optionally be provided between members of the set of drive pinion gears 210, between the first transmission housing 200 and the set of drive pinion gears 210, between the second transmission housing 202 and the set of drive pinion gears 210, or combinations thereof. The first countershaft gear set 212 is received in the transmission housing cavity 206 and may be in meshing engagement with the set of drive pinion gears 210. The first countershaft gear set 212 may be rotatable about a first countershaft axis 250. The first countershaft axis 250 may be disposed parallel or substantially parallel to the axis 70 in one or more embodiments. The term “substantially parallel” as used herein means the same as or very close to parallel and includes features or axes that are within ±3° of being parallel each other. The first countershaft gear set 212 may include a first countershaft 260 and a plurality of gears. In the configuration shown, the plurality of gears of the first countershaft gear set 212 comprise a first countershaft gear 270, a second countershaft gear 272, a third countershaft gear 274, and a fourth countershaft gear 276; however, it is contemplated that a greater number of countershaft gears or a lesser number of countershaft gears may be provided. The first countershaft 260 is rotatable about the first countershaft axis 250. For instance, the first countershaft 260 may be rotatably supported on the first transmission housing 200 and the second transmission housing 202 by corresponding bearing assemblies 280. For example, first and second bearing assemblies 280 may be located near opposing first and second ends the first countershaft 260, respectively. The first countershaft 260 may support and be rotatable with the first countershaft gear 270, the second countershaft gear 272, the third countershaft gear 274, and the fourth countershaft gear 276. The first countershaft gear 270 is fixedly disposed on the first countershaft 260 or fixedly mounted to the first countershaft 260. As such, the first countershaft gear 270 may rotate about the first countershaft axis 250 with the first countershaft 260 and may not be rotatable with respect to the first countershaft 260. For example, the first countershaft gear 270 may comprise a hole that may receive the first countershaft 260 and may be fixedly coupled to the first countershaft 260. The first countershaft gear 270 may extend around the first countershaft axis 250 and may comprise a plurality of teeth that may be arranged around and may extend away from the first countershaft axis 250. The teeth of the first countershaft gear 270 may contact and may mate or mesh with the teeth of the first gear 220. In some configurations, the first countershaft gear 270 is axially positioned along the first countershaft axis 250 between the first transmission housing 200 and the second countershaft gear 272 of the first countershaft gear set 212. The second countershaft gear 272 is fixedly disposed on the first countershaft 260 or fixedly mounted to the first countershaft 260. As such, the second countershaft gear 272 may rotate about the first countershaft axis 250 with the first countershaft 260 and may not be rotatable with respect to the first countershaft 260. For example, the second countershaft gear 272 may comprise a hole that may receive the first countershaft 260 and may be fixedly coupled to the first countershaft 260. The second countershaft gear 272 may extend around the first countershaft axis 250 and may comprise a plurality of teeth that may be arranged around and may extend away from the first countershaft axis 250. The teeth of the second countershaft gear 272 may contact and may mate or mesh with the teeth of the second gear 222. The second countershaft gear 272 may comprise a different diameter than the first countershaft gear 270 and the third countershaft gear 274. In some configurations, the second countershaft gear 272 is axially positioned along the first countershaft axis 250 between the first countershaft gear 270 of the first countershaft gear set 212 and the third countershaft gear 274 of the first countershaft gear set 212. The third countershaft gear 274 is fixedly disposed on the first countershaft 260 or fixedly mounted to the first countershaft 260. As such, the third countershaft gear 274 may rotate about the first countershaft axis 250 with the first countershaft 260 and may not be rotatable with respect to the first countershaft 260. For example, the third countershaft gear 274 may comprise a hole that may receive the first countershaft 260 and may be fixedly coupled to the first countershaft 260. The third countershaft gear 274 may extend around the first countershaft axis 250 and may comprise a plurality of teeth that may be arranged around and may extend away from the first countershaft axis 250. The teeth of the third countershaft gear 274 may contact and may mate or mesh with the teeth of the third gear 224. The third countershaft gear 274 may comprise a different diameter than the first countershaft gear 270 and the second countershaft gear 272. In some configurations, the third countershaft gear 274 is axially positioned along the first countershaft axis 250 between the second countershaft gear 272 of the first countershaft gear set 212 and the fourth countershaft gear 276 of the first countershaft gear set 212. The fourth countershaft gear 276 is fixedly disposed on the first countershaft 260 or fixedly mounted to the first countershaft 260. As such, the fourth countershaft gear 276 may rotate about the first countershaft axis 250 with the first countershaft 260 and may not be rotatable with respect to the first countershaft 260. For example, the fourth countershaft gear 276 may comprise a hole that may receive the first countershaft 260 and may be fixedly coupled to the first countershaft 260 or may be integrally formed with the first countershaft 260. The fourth countershaft gear 276 may extend around the first countershaft axis 250 and may comprise a plurality of teeth that may be arranged around and may extend away from the first countershaft axis 250. The teeth of the fourth countershaft gear 276 may contact and may mate or mesh with the teeth of the fourth gear 226. The fourth countershaft gear 276 may comprise a different diameter than the first countershaft gear 270, the second countershaft gear 272, and the third countershaft gear 274. In some configurations, the fourth countershaft gear 276 is axially positioned along the first countershaft axis 250 farther from the electric motor module 26 than the third countershaft gear 274 of the first countershaft gear set 212. The second countershaft gear set 214, if provided, is received in the transmission housing cavity 206 and may be rotatable about a second countershaft axis 250’. The second countershaft axis 250’ may be disposed parallel or substantially parallel to the axis 70 and the first countershaft axis 250 in one or more embodiments. The second countershaft gear set 214 may generally be disposed on an opposite side of the axis 70 from the first countershaft gear set 212 or may be disposed such that the first countershaft axis 250 and the second countershaft axis 250’ may be disposed at a common radial distance from the axis 70. The first and second countershaft gear sets 212, 214 may be positioned at any suitable rotational angle or position about the axis 70. The second countershaft gear set 214 may comprise the same or substantially the same configuration as the first countershaft gear set 212. For example, the second countershaft gear set 214 may include a second countershaft 260’ that may be analogous to or may comprise the same structure as the first countershaft 260. In addition, the second countershaft gear set 214 may include a plurality of gears that are rotatable with the second countershaft 260’. In the configuration shown, the plurality of gears of the second countershaft gear set 214 include a first countershaft gear 270’, a second countershaft gear 272’, a third countershaft gear 274’, and a fourth countershaft gear 276’; however, it is contemplated that a greater number of gears or a lesser number of gears may be provided. The first countershaft gear 270’, second countershaft gear 272’, third countershaft gear 274’, and the fourth countershaft gear 276’ of the second countershaft gear set 214 may be analogous to or may comprise the same structure as the first countershaft gear 270, second countershaft gear 272, third countershaft gear 274, and the fourth countershaft gear 276, respectively, of the first countershaft gear set 212. The first countershaft gear 270’, the second countershaft gear 272’, the third countershaft gear 274’, and the fourth countershaft gear 276’ may be arranged along and may be rotatable about a second countershaft axis 250’ rather than the first countershaft axis 250 and may be fixed to the second countershaft 260’ rather than the first countershaft 260. The first gear 220 and the first countershaft gears 270, 270’ may provide a different gear ratio than the second gear 222 and the second countershaft gears 272, 272’, the third gear 224 and the third countershaft gears 274, 274’, and the fourth gear 226 and the fourth countershaft gears 276, 276’. Gear ratios may be provided that are greater than 1:1, less than 1:1, equal (i.e., 1:1), or combinations thereof. The teeth of the drive pinion gears and the countershaft gears may be of any suitable type. As a non-limiting example, the meshing teeth of the members of the set of drive pinion gears 210, the gears of the first countershaft gear set 212, and the gears of the second countershaft gear set 214 may comprise a helical configuration. Referring primarily to Figures 2, 5 and 6, the shift mechanism 32 is configured to selectively connect a member of the set of drive pinion gears 210 to the drive pinion 30. For example, the shift mechanism 32 may operatively connect a member of the set of drive pinion gears 210 to the drive pinion 30 to provide torque at a desired gear ratio, and hence may change the torque transmitted between the electric motor module 26 and the differential assembly 22. The shift mechanism 32 may couple one member of the set of drive pinion gears 210 at a time to the drive pinion 30. The member of the set of drive pinion gears 210 that is coupled to the drive pinion 30 may be rotatable about the axis 70 with the drive pinion 30. The shift mechanism 32 may be received in or partially received in a shift mechanism cavity 300, which is best shown in Figures 2 and 3. The shift mechanism cavity 300 may be at least partially defined by the second transmission housing 202 may be disposed proximate an end of the axle assembly 10. Referring to Figures 1 and 2, a cover 302 may enclose an end of the axle assembly 10 and help define the shift mechanism cavity 300. The cover 302 may be mounted on the end of the second transmission housing 202 to help enclose the shift mechanism cavity 300. The cover 302 may be a single component or may be an assembly of multiple parts. A portion of the cover 302 is removed in Figure 3. The shift mechanism 32 may comprise any suitable configuration. In some configurations such as is shown in Figure 5, the shift mechanism 32 includes a shift collar 310, an actuator 312, a detent linkage 314, a linkage 316, and a collar 318. The shift mechanism 32 may also include a biasing member 322, a detent linkage pin 324, and a linkage pin 326. Referring primarily to Figures 5-7, the shift collar 310 is rotatable about the axis 70 with the drive pinion 30. In addition, the shift collar 310 is moveable along the axis 70 with respect to the drive pinion 30. The shift collar 310 may selectively connect a member of the set of drive pinion gears 210 to the drive pinion 30 as will be discussed in more detail below. The shift collar 310 may be at least partially received in the shift mechanism cavity 300 and may be extendable through components of the transmission 204, such as the set of drive pinion gears 210. In some configurations, the shift collar 310 comprises a first end 330, a second end 332, a shift collar hole 334, and a shift collar spline 336. The shift collar 310 may also include a first tubular shift collar portion 340, a second tubular shift collar portion 342, a shift collar gear 344, a threaded portion 348 or combinations thereof. Referring primarily to Figure 6, the first end 330 faces toward the drive pinion 30. In addition, the first end 330 may be disposed adjacent to the drive pinion 30 or the drive pinion extension 90. The second end 332 is disposed opposite the first end 330. As such, the second end 332 may face away from the drive pinion 30. The shift collar hole 334 extends along the axis 70 between the first end 330 and the second end 332. In some configurations, the shift collar hole 334 is configured as a through hole that may extend from the first end 330 to the second end 332. The drive pinion 30 or the drive pinion extension 90 may be received inside the shift collar hole 334. Referring to Figures 5 and 7, the shift collar spline 336 couples the shift collar 310 to the drive pinion 30 or the drive pinion extension 90. The shift collar spline 336 may be disposed in the shift collar hole 334 and may be axially positioned near the first end 330. The shift collar spline 336 may extend toward the axis 70 and may mate with a spline of the drive pinion 30 or the spline 98 of the drive pinion extension 90 that may comprise spline teeth that may extend away from the axis 70. The mating splines may allow the shift collar 310 to move in an axial direction or along the axis 70 while inhibiting rotation of the shift collar 310 about the axis 70 with respect to the drive pinion 30. Thus, the shift collar 310 may be rotatable about the axis 70 with the drive pinion 30 when the shift collar spline 336 mates with the spline of the drive pinion 30 or the drive pinion extension 90. The first tubular shift collar portion 340 may extend from the first end 330 toward the second end 332. The first tubular shift collar portion 340 may comprise a hollow tubular configuration and may be at least partially received inside the set of drive pinion gears 210 of the transmission 204. The first tubular shift collar portion 340 may comprise a larger outside diameter than the second tubular shift collar portion 342. The second tubular shift collar portion 342, if provided, may extend from the second end 332 toward the first tubular shift collar portion 340 or to the first tubular shift collar portion 340. For instance, the second tubular shift collar portion 342 may comprise a hollow tubular configuration and may be at least partially disposed outside of the set of drive pinion gears 210. The shift collar gear 344 may be disposed between the first end 330 and the second end 332 of the shift collar 310. In some configurations, the shift collar gear 344 is disposed opposite the shift collar hole 334 and may extend from the first tubular shift collar portion 340. The shift collar gear 344 may comprise teeth that may be arranged around the axis 70 and that may extend away from the axis 70 and away from the shift collar hole 334. The shift collar spline 336 may be disposed opposite the shift collar gear 344. The shift collar gear 344 is engageable with different members of the set of drive pinion gears 210 as will be discussed in more detail below. The threaded portion 348 may be axially positioned between the first end 330 and the second end 332. For instance, the threaded portion 348 may be provided with the second tubular shift collar portion 342 and may be axially positioned between the first tubular shift collar portion 340 and the second end 332. The threaded portion 348 may be disposed on an exterior side of the second tubular shift collar portion 342 that may face away from the axis 70. It is also contemplated that the threaded portion 348 may be omitted. Referring to Figure 5, the actuator 312 is configured to move the shift collar 310 along the axis 70 to selectively connect a member of the set of drive pinion gears 210 to the drive pinion 30. The actuator 312 may be of any suitable type, such as an electrical, electromechanical, or mechanical actuator. In some configurations, the actuator 312 is mounted to the second transmission housing 202. A portion of the actuator 312 may be rotatable about an actuator axis 350. For instance, the actuator 312 may comprise an actuator shaft 352 that may extend along the actuator axis 350 and may be rotatable about the actuator axis 350. The actuator shaft 352 may be operatively connected to the detent linkage 314. Referring to Figure 5 and 7, the detent linkage 314 is coupled to the actuator 312. For instance, the detent linkage 314 may be fixedly coupled to the actuator shaft 352. As such, the detent linkage 314 may be rotatable about the actuator axis 350 with the actuator shaft 352. The detent linkage 314 may define a plurality of recesses 360. The recesses 360 may be configured to receive a detent feature 362. The detent feature 362 may resist, restrict, or inhibit rotation of the detent linkage 314 about the actuator axis 350 when the detent feature 362 is received in a recess 360. For example, rotation of the detent linkage 314 may be inhibited or resisted when the detent feature 362 is in a recess 360 and a sufficient actuation force is not provided by the actuator 312 to overcome the rotational resistance exerted by the detent feature 362. The detent linkage 314 may be rotatable about the actuator axis 350 with respect to the linkage 316. The linkage 316 may operatively connect the actuator 312 to the shift collar 310. In some configurations, the linkage 316 is positioned along the actuator axis 350 closer to the actuator 312 than the detent linkage 314 is positioned to the actuator 312, although it is contemplated that this positioning may be reversed. The linkage 316 may be rotatable about the actuator axis 350. In some configurations, the linkage 316 is rotatably disposed on the detent linkage 314 and is rotatable about the actuator axis 350. The linkage 316 may rotate with the detent linkage 314 at some times, such as when a blocked shift condition is not present, but may rotate with respect to the detent linkage 314 when a blocked shift condition is present. The linkage 316 comprises a first limit pin 370 and a second limit pin 372. Referring primarily to Figure 12, the first limit pin 370 extends from the linkage 316. For instance, the first limit pin 370 may extend from the linkage 316 toward the detent linkage 314 and may be fixedly positioned with respect to the linkage 316. The first limit pin 370 may be spaced apart from the detent linkage 314, the detent linkage pin 324, the linkage pin 326, the second limit pin 372, or combinations thereof. The first limit pin 370 may have a shorter axial length than the linkage pin 326. As such, the linkage pin 326 may protrude farther from the linkage 316 than the first limit pin 370. The first limit pin 370 may be radially positioned closer to the actuator axis 350 than the linkage pin 326, the second limit pin 372, or both. The second limit pin 372 extends from the linkage 316. For instance, the second limit pin 372 may extend from the linkage 316 toward the detent linkage 314 and may be fixedly positioned with respect to the linkage 316. The second limit pin 372 may be spaced apart from the detent linkage 314, the detent linkage pin 324, the linkage pin 326, or combinations thereof. The second limit pin 372 may have a shorter axial length than the linkage pin 326. As such, the linkage pin 326 may protrude farther from the linkage 316 than the second limit pin 372. The second limit pin 372 may be radially positioned closer to the actuator axis 350 than the linkage pin 326. Referring to Figures 5 and 6, the collar 318 may receive the shift collar 310. The collar 318 may extend at least partially around the axis 70 in the shift collar 310. For instance, the collar 318 may be configured as a ring that may extend around the axis 70. The collar 318 may be coupled to the linkage 316 as will be discussed in more detail below. In some configurations and as is best shown in Figure 6, the collar 318 comprises a first collar side 440, a second collar side 442, and a collar hole 444. The collar 318 may also include a collar arm 446 and a shift block 448. The first collar side 440 may face toward the transmission module 28, the drive pinion 30, or both. The second collar side 442 may be disposed opposite the first collar side 440. As such, the second collar side 442 may face away from the transmission module 28, the drive pinion 30, or both. The collar hole 444 extends between the first collar side 440 and the second collar side 442. The collar hole 444 may be a through hole that may extend through the collar 318. The shift collar 310 is received inside the collar hole 444 and may be rotatable about the axis 70 with respect to the collar 318. For instance, the second tubular shift collar portion 342 may be received inside the collar hole 444 and may extend through the collar hole 444. In some configurations, the collar hole 444 receives a bearing assembly that may be positioned between the shift collar 310 and the collar 318. For example, the bearing assembly may extend from an outside circumference of the second tubular shift collar portion 342 to the inside diameter of the collar 318 that defines the collar hole 444. Referring primarily to Figures 5-7, the collar arm 446, if provided, extends from the collar 318. For instance, the collar arm 446 may extend from the collar 318 in a direction that extends away from the axis 70. In the configuration shown, the collar arm 446 is shown extending at an oblique angle from the collar 318 and is angled away from the transmission 204; however, it is contemplated that the collar arm 446 may be angled toward the transmission 204 or may be disposed substantially perpendicular to the axis 70. 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 ±3° of being perpendicular each other. The collar arm 446 may be integrally formed with the collar 318 or may be a separate component that is fastened to the collar 318. In the configuration shown, the collar arm 446 is illustrated as being integrally formed with the collar 318 and is disposed below the axis 70. The collar arm 446 is moveably disposed on an alignment rod 450. The collar arm 446 and the alignment rod 450 may cooperate to limit or inhibit rotation of the collar 318 about the axis 70. The alignment rod 450 is disposed on the shift mechanism cavity 300. For instance, the alignment rod 450 may be received in the shift mechanism cavity 300 and may be mounted to the second transmission housing 202, the cover 302, or both. In the configuration shown, the alignment rod 450 is shown as being received in a pocket or recess in the cover 302 and in a pocket of the second transmission housing 202. The alignment rod 450 may be fixedly disposed on the cover 302 or the second transmission housing 202 or may be disposed in a manner in which movement of the alignment rod 450 is limited. For example, the alignment rod 450 may slide along the axis 70 and / or rotate about the axis 70 but may remain in its axial orientation. The alignment rod 450 may be disposed substantially parallel to the axis 70. In some configurations, the alignment rod 450 is disposed below the axis 70, below the shift collar 310, or both. In some configurations, the collar arm 446 comprises an opening in which the alignment rod 450 may be received. The opening may be a hole, recess, slot, or the like inside which the alignment rod 450 may be received. It is also contemplated that the alignment rod 450 may define a recess or slot that extends along its axial length and a portion of the alignment rod 450, such as the end of the alignment rod 450, may be received in the recess or slot in the alignment rod 450. Referring to Figure 6, the shift block 448, if provided, may be fixedly positioned with respect to the collar 318. The shift block 448 may be integrally formed with the collar 318 or may be provided as a separate component that is attached to the collar 318. For instance, the shift block 448 may extend from an outside circumference of the collar 318, the second collar side 442, or combinations thereof. The shift block 448, if provided, may facilitate mounting of a fastener 452 that may connect or couple the linkage 316 to the collar 318. The first thrust bearing 410 facilitates rotation of the shift collar 310 about the axis 70 with respect to the collar 318. The first thrust bearing 410 may be axially positioned between the first collar side 440 and the shift collar 310. Optionally, washers may be axially positioned adjacent to one or both sides of the first thrust bearing 410. The second thrust bearing 412 facilitates rotation of the shift collar 310 about the axis 70 with respect to the collar 318. The second thrust bearing 412 may be positioned between the second collar side 442 and the retainer nut 414. Optionally a washer may be axially positioned adjacent to one or both sides of the second thrust bearing 412. For example, a washer may be provided between the second thrust bearing 412 and the retainer nut 414. The retainer nut 414 is configured to be mounted to the shift collar 310. For instance, the retainer nut 414 may comprise a threaded hole that may receive the second tubular shift collar portion 342 and mate with the threaded portion 348 of the shift collar 310. The retainer nut 414 may inhibit axial movement of the shift collar 310 with respect to the collar 318 and may help secure the first thrust bearing 410 and the second thrust bearing 412. It is also contemplated that the retainer nut 414 may be omitted and a different fastener or fastening technique may be used. For instance, a fastener like a pin, snap ring, or a press-fit fastener may replace a threaded connection. An encoder disc 416 may optionally be mounted to the drive pinion 30 or the drive pinion extension 90. In some configurations, the encoder disc 416 is disposed adjacent to the retainer nut 414. For instance, the encoder disc 416 may be axially positioned between the retainer nut 414 and a support bearing 418 that rotatably supports the drive pinion 30 or drive pinion extension 90. For example, the support bearing 418 may be positioned between a shoulder of the drive pinion 30 or drive pinion extension 90 and the support bearing 418, if provided. The encoder disc 416 may comprise detectable features such as protrusions and / or recesses that may be detectable by a sensor to detect rotation or the rotational speed of the drive pinion 30. The support bearing 418 may rotatably support the drive pinion 30 or drive pinion extension 90. For instance, the drive pinion 30 or drive pinion extension 90 may be received inside and may be rotatably supported by the support bearing 418, which in turn may be supported by the second transmission housing 202, the cover 302, or both. Referring to Figure 5, the biasing member 322 operatively connects the detent linkage 314 to the linkage 316. In addition, the biasing member 322 may control relative rotational movement between the detent linkage 314 and the linkage 316 (e.g., rotational movement of the linkage 316 with respect to the detent linkage 314). For example, the biasing member 322 may permit the actuator shaft 352 and the detent linkage 314 to rotate about the actuator axis 350 with respect to the linkage 316 when the shift collar 310 is inhibited from moving along the axis 70, such as during a blocked shift as will be discussed in more detail below. The biasing member 322 may be positioned along the actuator axis 350 between the detent linkage 314 and the linkage 316. The biasing member 322 may comprise any suitable configuration. For instance, the biasing member 322 may be configured as a spring, such as a torsion spring. In some configurations, the biasing member 322 comprises a first leg 380 and a second leg 382. The first leg 380 may be a first free end of the biasing member 322. The second leg 382 may be a second free end of the biasing member 322 that is disposed opposite the first leg 380. The first leg 380 may be spaced apart from the second leg 382. The first leg 380 and the second leg 382 may extend away from the actuator axis 350. The detent linkage pin 324 extends from the detent linkage 314 toward the linkage 316. The detent linkage pin 324 is spaced apart from the linkage 316. The detent linkage pin 324 is fixedly positioned with respect to the detent linkage 314. The detent linkage pin 324 may engage a leg of the biasing member 322. The detent linkage pin 324 may be disposed between or extend between the first leg 380 and the second leg 382. The linkage pin 326 extends from the linkage 316. The linkage pin 326 may be spaced apart from the detent linkage pin 324 and the detent linkage 314. The linkage pin 326 is fixedly positioned with respect to the linkage 316. The linkage pin 326 may engage the same leg and / or a different leg of the biasing member 322. The linkage pin 326 may be disposed between the first leg 380 and the second leg 382. The first limit pin 370 and the second limit pin 372 may not extend between the first leg 380 and the second leg 382. Operation of the shift mechanism 32 will now be discussed. As an overview, various components of the shift mechanism 32 may move together when the shift collar 310 is free to move along the axis 70. For instance, components such as the actuator shaft 352, detent linkage 314, linkage 316, and the biasing member 322 may rotate together about the actuator axis 350 when the actuator shaft 352 is rotated and the shift collar 310 is free to move along the axis 70. However, some of these components may move respect to each other when the shift collar 310 is not free to move along the axis 70. For example, the actuator shaft 352 and the detent linkage 314 may be rotatable with respect to the linkage 316 when the shift collar 310 is not free to move along the axis 70. The shift collar 310 may not be free to move along the axis 70 when the rotational speed of the shift collar 310 about the axis 70 is not sufficiently synchronized with the rotational speed of a member of the set of drive pinion gears 210. For instance, the shift collar 310 may be blocked from shifting or moving along the axis 70 when the teeth of the shift collar gear 344 are inhibited from entering the gaps between the inner gear teeth of a drive pinion gear or exiting the gaps between the inner gear teeth of a drive pinion gear. Similarly, sufficient friction between teeth of the shift collar gear 344 and teeth of a member of the set of drive pinion gears 210 may provide resistance that resists actuation of the shift collar 310 along the axis 70 to disengage a member of the set of drive pinion gears 210. Either case may be referred to as a blocked shift or a blocked shift condition. Referring to Figures 7-11, examples that depict actuation of the shift collar 310 when a blocked shift condition is not present are shown. In these examples, the first leg 380 and the second leg 382 of the biasing member 322 may remain in engagement or contact with the detent linkage pin 324 and the linkage pin 326 during actuation. As such, the detent linkage pin 324 and the linkage pin 326 may not move away from each other to actuate the biasing member 322 and store additional potential energy in the biasing member 322. The actuator 312 may move the shift collar 310 along the axis 70 between a plurality of positions to selectively couple the shift collar 310 to the transmission 204 or to decouple the shift collar 310 from the transmission 204. For instance, the actuator 312 may move the shift collar 310 along the axis 70 between the first, second, and third positions. Examples of these positions are illustrated in Figures 7, 9, and 11. The actuator 312 may also move the shift collar 310 along the axis 70 to first and second neutral positions, which are best shown in Figures 8 and 10. It is noted that in Figures 7-11 only a portion of the transmission 204 is shown to better illustrate movement of the shift collar 310. In the examples below, reference to connecting or disconnecting a member of the set of drive pinion gears 210 to / from the drive pinion 30 includes direct and indirect connections to and disconnections from the drive pinion 30. For instance, a member of the set of drive pinion gears 210 may be directly coupled to the drive pinion 30 or indirectly connected to the drive pinion 30 such as via the drive pinion extension 90. Referring to Figure 7, the shift collar 310 is shown in the first position. In the first position, the shift collar 310 may couple the fourth gear 226 to the drive pinion 30. For example, the teeth of the shift collar gear 344 may mesh with the inner gear teeth 236 of the fourth gear 226. Torque may be transmitted from the rotor 106 to the first gear 220 such as via the rotor output flange 130, from the first gear 220 to the first countershaft gears 270, 270’, from the first countershaft gears 270, 270’ to the fourth countershaft gears 276, 276’ via the first and second countershafts 260, 260’, respectively, from the fourth countershaft gears 276, 276’ to the fourth gear 226, and from the fourth gear 226 to the drive pinion 30 via the shift collar gear 344 of the shift collar 310. The first gear 220, the second gear 222, and the third gear 224 may be rotatable about the axis 70. Torque may be provided at the first gear ratio in the first position, such as a low-speed gear ratio. Referring to Figure 8, the shift collar 310 is shown in the first neutral position. In the first neutral position, the shift collar 310 may not couple any member of the set of drive pinion gears 210 to the drive pinion 30. As such, the teeth of the shift collar gear 344 may be spaced apart from or may not mesh with inner gear teeth of the second gear 222, the third gear 224, and the fourth gear 226. The teeth of the shift collar gear 344 may be axially positioned between the inner gear teeth 234 of the third gear 224 and the inner gear teeth 236 of the fourth gear 226. As such, the first gear 220, the second gear 222, the third gear 224, and the fourth gear 226 may be rotatable about the axis 70 with respect to the drive pinion 30 when the shift collar 310 is in the first neutral position and torque may not be transmitted between the transmission 204 and the drive pinion 30. The first neutral position may be positioned between the first position shown in Figure 7 and the second position shown in Figure 9. Referring to Figure 9, the shift collar 310 is shown in the second position. In the second position, the shift collar 310 may couple the third gear 224 to the drive pinion 30. For example, the teeth of the shift collar gear 344 may mesh with the inner gear teeth 234 of the third gear 224. Torque may be transmitted from the rotor 106 to the first gear 220 such as via the rotor output flange 130, from the first gear 220 to the first countershaft gears 270, 270’, from the first countershaft gears 270, 270’ to the third countershaft gears 274, 274’ via the first and second countershafts 260, 260’, respectively, from the third countershaft gears 274, 274’ to the third gear 224, and from the third gear 224 to the drive pinion 30 via the shift collar gear 344 of the shift collar 310. As such, the first gear 220, the second gear 222, and the fourth gear 226 may be rotatable about the axis 70 with respect to the drive pinion 30 when the second gear ratio is provided. Torque may be provided at the second gear ratio in the second position, such as a mid- speed gear ratio. Referring to Figure 10, the shift collar 310 is shown in the second neutral position. In the second neutral position, the shift collar 310 may not couple any member of the set of drive pinion gears 210 to the drive pinion 30. As such, the teeth of the shift collar gear 344 may be spaced apart from or may not mesh with inner gear teeth of the second gear 222, the third gear 224, and the fourth gear 226. The teeth of the shift collar gear 344 may be axially positioned between the inner gear teeth 234 of the third gear 224 and the inner gear teeth 232 of the second gear 222. As such, the first gear 220, the second gear 222, the third gear 224, and the fourth gear 226 may be rotatable about the axis 70 with respect to the drive pinion 30 when the shift collar 310 is in the second neutral position and torque may not be transmitted between the transmission 204 and the drive pinion 30. The second neutral position may be positioned between the second position shown in Figure 9 and the third position shown in Figure 11. Referring to Figure 11, the shift collar 310 is shown in the third position. In the third position, the shift collar 310 may couple the second gear 222 to the drive pinion 30. For example, the teeth of the shift collar gear 344 may mesh with the inner gear teeth 232 of the second gear 222. Torque may be transmitted from the rotor 106 to the first gear 220 such as via the rotor output flange 130, from the first gear 220 to the first countershaft gears 270, 270’, from the first countershaft gears 270, 270’ to the second countershaft gears 272, 272’ via the first and second countershafts 260, 260’, respectively, from the second countershaft gears 272, 272’ to the second gear 222, and from the second gear 222 to the drive pinion 30 via the shift collar gear 344 of the shift collar 310. The shift collar gear 344 may not engage the inner gear teeth 234 of the third gear 224 or the inner gear teeth 236 of the fourth gear 226. As such, the first gear 220, the third gear 224, and the fourth gear 226 may be rotatable about the axis 70 with respect to the drive pinion 30 when the third gear ratio is provided. Torque may be provided at the third gear ratio in the third position, such as a high-speed gear ratio. Referring to Figures 13-28, examples that depict actuation of the shift collar 310 when a blocked shift condition is present are shown. In these examples, the first leg 380 and the second leg 382 of the biasing member 322 do not remain in engagement or contact with the detent linkage pin 324 and the linkage pin 326 throughout the actuation sequence. As such, there is relative movement of the detent linkage 314 with respect to the linkage 316 at various points in the actuation sequences. Relative rotational movement of the detent linkage 314 with respect to the linkage 316 is accommodated by the biasing member 322 when there is a blocked shift. As an example, the detent linkage pin 324 may remain in engagement with the one leg of the biasing member 322 but may be rotated to disengage or move away from the other leg of the biasing member 322. The linkage pin 326 may remain in engagement with the other leg but may be disengaged from the one arm. This relative rotational movement may store potential energy in the biasing member 322. The potential energy may be released when the blocked shift condition is no longer present, such as when the rotational speed of the shift collar 310 is sufficiently synchronized with the rotational speed of a member of the set of drive pinion gears 210 to permit axial movement of the shift collar 310 or when the biasing force of the biasing member 322 is sufficient to overcome frictional resistance and actuate the shift collar 310 along the axis 70. As a result, the actuator 312 may complete its intended rotation of the actuator shaft 352 as if the shift collar 310 not blocked even when a blocked shift condition is present, thereby avoiding heating / overheating of the actuator 312 and the consumption of energy that would occur if the actuator 312 had to continuously work or exert force to attempt to complete shifting of the shift collar 310. Moreover, sufficient potential energy may be stored in the biasing member 322 that may be released to complete a shift of the shift collar 310 when sufficient synchronization is obtained or frictional resistance is overcome. The examples below are associated with different biasing member configurations and are discussed in four groups. Figures 13-20 are associated with a biasing member 322 that has a first configuration, such as a configuration in which the biasing member 322 is wound in a first rotational direction such as a counterclockwise direction. Figures 21-28 are associated with a biasing member 322 that has a second configuration, such as a configuration in which the biasing member 322 is wound in a second rotational direction that is opposite the first rotational direction, such as a clockwise direction. Figures 13-16 show an actuation sequence that accommodates a blocked shift from the first position to the first neutral position. Figures 17-20 show an actuation sequence that accommodates a blocked shift from the second position to the first neutral position, or in the opposite direction from that shown in Figures 13-16. Figures 21-24 show an actuation sequence that accommodates a blocked shift from the first position to the first neutral position. Figures 25-28 show an actuation sequence that accommodates a blocked shift from the second position to the first neutral position, or in the opposite direction from that shown in Figures 21-24. The examples in Figures 13-28 are applicable to other shift collar positions. For instance, the actuation sequence in Figures 13-16 and 21-24 are applicable to other blocked shifts in the same direction, such as from the first neutral position to the second position, from the second position to the second neutral position, and so on. Similarly, the actuation sequence in Figures 17- 20 and 25-28 are applicable to other blocked shifts in the same direction, such as from the third position to the second neutral position, from the second neutral position to the second position, and so on. Referring to Figures 13-16, a first blocked shift actuation sequence is shown. Referring to Figure 13, the shift collar 310 is shown in the first position and the detent linkage 314 is disposed in a first rotational position. The teeth of the shift collar gear 344 mesh with the inner gear teeth 236 of the fourth gear 226 and thus the shift collar 310 couples the fourth gear 226 to the drive pinion 30. The first leg 380 and the second leg 382 of the biasing member 322 engage or contact the detent linkage pin 324 and the linkage pin 326, noting that the second leg 382 extends over the second limit pin 372 from the perspective shown. The first leg 380 is spaced apart from and does not engage the first limit pin 370 or the second limit pin 372. The second leg 382 is spaced apart from and does not engage the first limit pin 370 or the second limit pin 372. The detent feature 362 is received in a first recess of the detent linkage 314. Referring to Figure 14, the detent linkage 314 is rotated about the actuation axis 350 in a counterclockwise direction from the perspective shown from the first rotational position to a second rotational position. In this example, the detent linkage 314 is rotated counterclockwise about the actuator axis 350 by approximately 7 degrees in response to force exerted by the actuator 312 (i.e., the actuator shaft 352 and the detent linkage 314 are rotated counterclockwise about the actuator axis 350 by approximately 7 degrees from the position in Figure 13). The force exerted by the actuator 312 is sufficient to overcome the force exerted by the detent feature 362 but is not sufficient to actuate the shift collar 310 along the axis 70. The detent feature 362 exits the first recess of the detent linkage 314 but is not yet rotated far enough to align with a second recess that is adjacent to the first recess. The linkage pin 326 remains in engagement with the second leg 382 and may be in substantially the same position as in Figure 13. Rotation of the detent linkage 314 about the actuator axis 350 causes the detent linkage pin 324 to disengage and move away from the second leg 382 and transmit force from the detent linkage 314 to the first leg 380 of the biasing member 322. The first leg 380 moves away from the second leg 382, thereby causing the first leg 380 to disengage and move away from the linkage pin 326 and increases the potential energy stored in the biasing member 322. Thus, potential energy is stored in the biasing member 322 when the detent linkage 314 moves from the first rotational position to the second rotational position. The first leg 380 moves into engagement with the first limit pin 370. Thus, the first leg 380 is sandwiched between the detent linkage pin 324 and the first limit pin 370. Referring to Figure 15, the detent linkage 314 is rotated about the actuation axis 350 in a counterclockwise direction from the perspective shown from the second rotational position to a third rotational position. In this example, the detent linkage 314 is rotated counterclockwise about the actuator axis 350 by approximately 6 additional degrees in response to force exerted by the actuator 312 (i.e., the actuator shaft 352 and the detent linkage 314 are rotated counterclockwise about the actuator axis 350 by approximately 6 degrees from the position in Figure 14). The detent linkage 314, the linkage 316, and the biasing member 322 rotate together about the actuator axis 350. The force exerted by the actuator 312 does not store additional potential energy in the biasing member 322 due to engagement of the first leg 380 and the first limit pin 370 but instead is transmitted to the shift collar 310. The force is sufficient to actuate the shift collar 310 along the axis 70 to the right from the perspective shown such that the shift collar gear 344 begins to disengage the inner gear teeth 236. The detent feature 362 enters the second recess of the detent linkage 314, thereby resisting further rotation of the detent linkage 314 and holding the detent linkage 314 in the third rotational position. Referring to Figure 16, potential energy is released from the biasing member 322 to actuate the shift collar 310 along the axis 70. The detent linkage 314 is held in the third rotational position and does not rotate about the actuator axis 350 with respect to the position shown in Figure 15. The potential energy released from the biasing member 322 rotates the linkage 316 about the actuator axis 350 with respect to the detent linkage 314 in a counterclockwise direction from the perspective shown. The released potential energy is transmitted to the shift collar 310 and actuates the shift collar 310 along the axis 70 to the right from the perspective shown to the first neutral position. The released potential energy and rotation of the linkage 316 causes the second leg 382 to move toward the first leg 380. The linkage pin 326 moves into engagement with the first leg 380. The second leg 382 moves into engagement with the detent linkage pin 324. The first leg 380 may remain in engagement with the first limit pin 370. Referring to Figures 17-20, a second blocked shift actuation sequence is shown. Referring to Figure 17, the shift collar 310 is shown in the second position and the detent linkage 314 is disposed in a fifth rotational position. The teeth of the shift collar gear 344 mesh with the inner gear teeth 234 of the third gear 224 and thus the shift collar 310 couples the third gear 224 to the drive pinion 30. The first leg 380 and the second leg 382 of the biasing member 322 engage or contact the detent linkage pin 324 and the linkage pin 326, noting that the second leg 382 extends over the second limit pin 372 from the perspective shown. The first leg 380 is spaced apart from and does not engage the first limit pin 370 or the second limit pin 372. The second leg 382 is spaced apart from and does not engage the first limit pin 370 or the second limit pin 372. The detent feature 362 is received in a third recess of the detent linkage 314. Referring to Figure 18, the detent linkage 314 is rotated about the actuation axis 350 in a clockwise direction from the perspective shown from the fifth rotational position to a fourth rotational position. In this example, the detent linkage 314 is rotated clockwise about the actuator axis 350 by approximately 7 degrees in response to force exerted by the actuator 312 (i.e., the actuator shaft 352 and the detent linkage 314 are rotated clockwise about the actuator axis 350 by approximately 7 degrees from the position in Figure 17). The force exerted by the actuator 312 is sufficient to overcome the force exerted by the detent feature 362 but is not sufficient to actuate the shift collar 310 along the axis 70. The detent feature 362 exits the third recess of the detent linkage 314 but is not yet rotated far enough to align with a second recess that is adjacent to the third recess. The linkage pin 326 remains in engagement with the first leg 380 and may be in substantially the same position as in Figure 17. Rotation of the detent linkage 314 about the actuator axis 350 causes the detent linkage pin 324 to disengage and move away from the first leg 380 and transmit force from the detent linkage 314 to the second leg 382 of the biasing member 322. The second leg 382 moves away from the first leg 380, thereby causing the second leg 382 to disengage and move away from the linkage pin 326 and increases the potential energy stored in the biasing member 322. Thus, potential energy is stored in the biasing member 322 when the detent linkage 314 moves from the fifth rotational position to the fourth rotational position. The detent linkage pin 324 moves into engagement with the second limit pin 372. Referring to Figure 19, the detent linkage 314 is rotated about the actuation axis 350 in a clockwise direction from the perspective shown from the fourth rotational position to the third rotational position. In this example, the detent linkage 314 is rotated clockwise about the actuator axis 350 by approximately 6 additional degrees in response to force exerted by the actuator 312 (i.e., the actuator shaft 352 and the detent linkage 314 are rotated clockwise about the actuator axis 350 by approximately 6 degrees from the position in Figure 18). The detent linkage 314, the linkage 316, and the biasing member 322 rotate together about the actuator axis 350. The force exerted by the actuator 312 does not store additional potential energy in the biasing member 322 due to engagement of the detent linkage pin 324 and the second limit pin 372 but instead is transmitted to the shift collar 310. The force is sufficient to actuate the shift collar 310 along the axis 70 to the left from the perspective shown such that the shift collar gear 344 begins to disengage the inner gear teeth 234. The detent feature 362 enters the second recess of the detent linkage 314, thereby resisting further rotation of the detent linkage 314 and holding the detent linkage 314 in the third rotational position. Referring to Figure 20, potential energy is released from the biasing member 322 to actuate the shift collar 310 along the axis 70. The detent linkage 314 is held in the third rotational position and does not rotate about the actuator axis 350 with respect to the position shown in Figure 19. The potential energy released from the biasing member 322 rotates the linkage 316 about the actuator axis 350 with respect to the detent linkage 314 in a clockwise direction from the perspective shown. The released potential energy is transmitted to the shift collar 310 and actuates the shift collar 310 along the axis 70 to the left from the perspective shown to the first neutral position. The released potential energy and rotation of the linkage 316 causes the first leg 380 to move toward the second leg 382. The linkage pin 326 moves into engagement with the second leg 382. The first leg 380 moves into engagement with the detent linkage pin 324. The second leg 382 may remain in engagement with the second limit pin 372. Referring to Figures 21-24, a third blocked shift actuation sequence is shown. Referring to Figure 21, the shift collar 310 is shown in the first position and the detent linkage 314 is disposed in a first rotational position. The teeth of the shift collar gear 344 mesh with the inner gear teeth 236 of the fourth gear 226 and thus the shift collar 310 couples the fourth gear 226 to the drive pinion 30. The first leg 380 and the second leg 382 of the biasing member 322 engage or contact the detent linkage pin 324 and the linkage pin 326, noting that the first leg 380 extends over the first limit pin 370 from the perspective shown. The first leg 380 is spaced apart from and does not engage the first limit pin 370 or the second limit pin 372. The second leg 382 is spaced apart from and does not engage the first limit pin 370 or the second limit pin 372. The detent feature 362 is received in a first recess of the detent linkage 314. Referring to Figure 22, the detent linkage 314 is rotated about the actuation axis 350 in a counterclockwise direction from the perspective shown from the first rotational position to a second rotational position. In this example, the detent linkage 314 is rotated counterclockwise about the actuator axis 350 by approximately 7 degrees in response to force exerted by the actuator 312 (i.e., the actuator shaft 352 and the detent linkage 314 are rotated counterclockwise about the actuator axis 350 by approximately 7 degrees from the position in Figure 21). The force exerted by the actuator 312 is sufficient to overcome the force exerted by the detent feature 362 but is not sufficient to actuate the shift collar 310 along the axis 70. The detent feature 362 exits the first recess of the detent linkage 314 but is not yet rotated far enough to align with a second recess that is adjacent to the first recess. The linkage pin 326 remains in engagement with the second leg 382 and may be in substantially the same position as in Figure 21. Rotation of the detent linkage 314 about the actuator axis 350 causes the detent linkage pin 324 to disengage and move away from the second leg 382 and transmit force from the detent linkage 314 to the first leg 380 of the biasing member 322. The first leg 380 moves away from the second leg 382, thereby causing the first leg 380 to disengage and move away from the linkage pin 326 and increases the potential energy stored in the biasing member 322. Thus, potential energy is stored in the biasing member 322 when the detent linkage 314 moves from the first rotational position to the second rotational position. The detent linkage 314 moves into engagement with the first limit pin 370. Referring to Figure 23, the detent linkage 314 is rotated about the actuation axis 350 in a counterclockwise direction from the perspective shown from the second rotational position to the third rotational position. In this example, the detent linkage 314 is rotated counterclockwise about the actuator axis 350 by approximately 6 additional degrees in response to force exerted by the actuator 312 (i.e., the actuator shaft 352 and the detent linkage 314 are rotated counterclockwise about the actuator axis 350 by approximately 6 degrees from the position in Figure 22). The detent linkage 314, the linkage 316, and the biasing member 322 rotate together about the actuator axis 350. The force exerted by the actuator 312 does not store additional potential energy in the biasing member 322 due to engagement of the detent linkage pin 324 and the first limit pin 370 but instead is transmitted to the shift collar 310. The force is sufficient to actuate the shift collar 310 along the axis 70 to the right from the perspective shown such that the shift collar gear 344 begins to disengage the inner gear teeth 236. The detent feature 362 enters the second recess of the detent linkage 314, thereby resisting further rotation of the detent linkage 314 and holding the detent linkage 314 in the third rotational position. Referring to Figure 24, potential energy is released from the biasing member 322 to actuate the shift collar 310 along the axis 70. The detent linkage 314 is held in the third rotational position and does not rotate about the actuator axis 350 with respect to the position shown in Figure 23. The potential energy released from the biasing member 322 rotates the linkage 316 about the actuator axis 350 with respect to the detent linkage 314 in a counterclockwise direction from the perspective shown. The released potential energy is transmitted to the shift collar 310 and actuates the shift collar 310 along the axis 70 to the right from the perspective shown to the first neutral position. The released potential energy and rotation of the linkage 316 causes the second leg 382 to move toward the first leg 380. The linkage pin 326 moves into engagement with the first leg 380. The second leg 382 moves into engagement with the detent linkage pin 324. The detent linkage pin 324 disengages the first limit pin 370. Referring to Figures 25-28, a fourth blocked shift actuation sequence is shown. Referring to Figure 25, the shift collar 310 is shown in the second position and the detent linkage 314 is disposed in a fifth rotational position. The teeth of the shift collar gear 344 mesh with the inner gear teeth 234 of the third gear 224 and thus the shift collar 310 couples the third gear 224 to the drive pinion 30. The first leg 380 and the second leg 382 of the biasing member 322 engage or contact the detent linkage pin 324 and the linkage pin 326, noting that the first leg 380 extends over the first limit pin 370 from the perspective shown. The first leg 380 is spaced apart from and does not engage the first limit pin 370 or the second limit pin 372. The second leg 382 is spaced apart from and does not engage the first limit pin 370 or the second limit pin 372. The detent feature 362 is received in a third recess of the detent linkage 314. Referring to Figure 26, the detent linkage 314 is rotated about the actuation axis 350 in a clockwise direction from the perspective shown from the fifth rotational position to a fourth rotational position. In this example, the detent linkage 314 is rotated clockwise about the actuator axis 350 by approximately 7 degrees in response to force exerted by the actuator 312 (i.e., the actuator shaft 352 and the detent linkage 314 are rotated clockwise about the actuator axis 350 by approximately 7 degrees from the position in Figure 25). The force exerted by the actuator 312 is sufficient to overcome the force exerted by the detent feature 362 but is not sufficient to actuate the shift collar 310 along the axis 70. The detent feature 362 exits the third recess of the detent linkage 314 but is not yet rotated far enough to align with a second recess that is adjacent to the third recess. The linkage pin 326 remains in engagement with the first leg 380 and may be in substantially the same position as in Figure 25. Rotation of the detent linkage 314 about the actuator axis 350 causes the detent linkage pin 324 to disengage and move away from the first leg 380 and transmit force from the detent linkage 314 to the second leg 382 of the biasing member 322. The second leg 382 moves away from the first leg 380, thereby causing the second leg 382 to disengage and move away from the linkage pin 326 and increases the potential energy stored in the biasing member 322. Thus, potential energy is stored in the biasing member 322 when the detent linkage 314 moves from the fifth rotational position to the fourth rotational position. The second leg 382 moves into engagement with the second limit pin 372. Thus, the second leg 382 may be sandwiched between the detent linkage pin 324 and the second limit pin 372. Referring to Figure 27, the detent linkage 314 is rotated about the actuation axis 350 in a clockwise direction from the perspective shown from the fourth rotational position to the third rotational position. In this example, the detent linkage 314 is rotated clockwise about the actuator axis 350 by approximately 6 additional degrees in response to force exerted by the actuator 312 (i.e., the actuator shaft 352 and the detent linkage 314 are rotated clockwise about the actuator axis 350 by approximately 6 degrees from the position in Figure 26). The detent linkage 314, the linkage 316, and the biasing member 322 rotate together about the actuator axis 350. The force exerted by the actuator 312 does not store additional potential energy in the biasing member 322 due to engagement of the second leg 382 and the second limit pin 372 but instead is transmitted to the shift collar 310. The force is sufficient to actuate the shift collar 310 along the axis 70 to the left from the perspective shown such that the shift collar gear 344 begins to disengage the inner gear teeth 234. The detent feature 362 enters the second recess of the detent linkage 314, thereby resisting further rotation of the detent linkage 314 and holding the detent linkage 314 in the third rotational position. Referring to Figure 28, potential energy is released from the biasing member 322 to actuate the shift collar 310 along the axis 70. The detent linkage 314 is held in the third rotational position and does not rotate about the actuator axis 350 with respect to the position shown in Figure 27. The potential energy released from the biasing member 322 rotates the linkage 316 about the actuator axis 350 with respect to the detent linkage 314 in a clockwise direction from the perspective shown. The released potential energy is transmitted to the shift collar 310 and actuates the shift collar 310 along the axis 70 to the left from the perspective shown to the first neutral position. The released potential energy and rotation of the linkage 316 causes the first leg 380 to move toward the second leg 382. The linkage pin 326 moves into engagement with the second leg 382. The first leg 380 moves into engagement with the detent linkage pin 324. The second leg 382 may disengage the second limit pin 372. The present invention may provide a shift mechanism that improves actuation of a shift collar. The present invention may better address blocked shift conditions by addressing situations in which resistance to shift collar movement exceeds the torque available from the biasing member by employing limit pins that allow potential energy to be stored in biasing member over a limited rotational distance and then help transmit torque to the shift collar to facilitate shift collar actuation. Potential energy may then be released from the biasing member to complete movement of the shift collar to a desired position. 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.

Claims

WHAT IS CLAIMED IS:

1. A shift mechanism comprising: an actuator that comprises an actuator shaft that is rotatable about an actuator axis; a detent linkage that is rotatable about the actuator axis with the actuator shaft; a linkage that is rotatable about the actuator axis; a detent linkage pin that extends from the detent linkage; a linkage pin, a first limit pin, and a second limit pin that extend from the linkage; a shift collar that is operatively connected to the linkage and moveable along an axis; and a biasing member that operatively connects the detent linkage to the linkage and that permits the actuator shaft and the detent linkage to rotate about the actuator axis with respect to the linkage when the shift collar is inhibited from moving along the axis.

2. The shift mechanism of claim 1 wherein the biasing member further comprises a first leg and a second leg and the detent linkage pin and the linkage pin are disposed between the first leg and the second leg.

3. The shift mechanism of claim 2 wherein the first limit pin and the second limit pin are not disposed between the first leg and the second leg.

4. The shift mechanism of claim 2 wherein the first leg and the second leg engage the detent linkage pin and the linkage pin and do not engage the first limit pin and the second limit pin when the detent linkage is in a first rotational position.

5. The shift mechanism of claim 4 wherein the first leg engages the detent linkage pin and the first limit pin, and the second leg engages the linkage pin and is disengaged from the detent linkage pin and the second limit pin when the detent linkage is in a second rotational position.

6. The shift mechanism of claim 5 wherein potential energy is stored in the biasing member when the detent linkage moves from the first rotational position to the second rotational position.

7. The shift mechanism of claim 6 wherein the shift collar does not move along the axis when the detent linkage moves from the first rotational position to the second rotational position.

8. The shift mechanism of claim 6 wherein the detent linkage and the linkage rotate together about the actuator axis and the shift collar moves along the axis when the detent linkage moves from the second rotational position toward a third rotational position.

9. The shift mechanism of claim 8 wherein potential energy released from the biasing member rotates the linkage about the actuator axis with respect to the detent linkage and actuates the shift collar along the axis when the detent linkage is in the third rotational position.

10. The shift mechanism of claim 2 wherein the first leg and the second leg engage the detent linkage pin and the linkage pin and do not engage the first limit pin and the second limit pin when the detent linkage is in a fifth rotational position.

11. The shift mechanism of claim 10 wherein the first leg engages the linkage pin and is disengaged from the detent linkage pin, and the second leg engages the detent linkage pin and is disengaged from the second limit pin, and the detent linkage pin engages the second limit pin when the detent linkage is in a fourth rotational position.

12. The shift mechanism of claim 11 wherein the detent linkage and the linkage rotate together about the actuator axis, and the shift collar moves along the axis when the detent linkage moves from the fourth rotational position toward a third rotational position.

13. The shift mechanism of claim 12 wherein potential energy released from the biasing member rotates the linkage about the actuator axis with respect to the detent linkage and actuates the shift collar along the axis when the detent linkage is in the third rotational position.

14. The shift mechanism of claim 2 wherein the first leg and the second leg engage the detent linkage pin and the linkage pin and do not engage the first limit pin and the second limit pin when the detent linkage is in a first rotational position.

15. The shift mechanism of claim 14 wherein the first leg engages the detent linkage pin, the detent linkage pin engages the first limit pin, and the second leg engages the linkage pin and is disengaged from the detent linkage pin and the second limit pin when the detent linkage is in a second rotational position.

16. The shift mechanism of claim 15 wherein potential energy is stored in the biasing member when the detent linkage moves from the first rotational position to the second rotational position.

17. The shift mechanism of claim 16 wherein the shift collar does not move along the axis when the detent linkage moves from the first rotational position to the second rotational position.

18. The shift mechanism of claim 16 wherein the detent linkage and the linkage rotate together about the actuator axis and the shift collar moves along the axis when the detent linkage moves from the second rotational position toward a third rotational position.

19. The shift mechanism of claim 18 wherein potential energy released from the biasing member rotates the linkage about the actuator axis with respect to the detent linkage and actuates the shift collar along the axis when the detent linkage is in the third rotational position.

20. The shift mechanism of claim 2 wherein the first leg and the second leg engage the detent linkage pin and the linkage pin and do not engage the first limit pin and the second limit pin when the detent linkage is in a fifth rotational position.

21. The shift mechanism of claim 20 wherein the first leg engages the linkage pin and is disengaged from the detent linkage pin, and the second leg engages the detent linkage pin and the second limit pin, and the second leg is disengaged from the linkage pin when the detent linkage is in a fourth rotational position.

22. The shift mechanism of claim 21 wherein the detent linkage and the linkage rotate together about the actuator axis, and the shift collar moves along the axis when the detent linkage moves from the fourth rotational position toward a third rotational position.

23. The shift mechanism of claim 22 wherein potential energy released from the biasing member rotates the linkage about the actuator axis with respect to the detent linkage and actuates the shift collar along the axis when the detent linkage is in the third rotational position.

Images