Patent ID: 12194841

DETAILED DESCRIPTION

In the following description, certain specific details are set forth in order to provide a thorough understanding of various disclosed embodiments. However, one skilled in the relevant art will recognize that embodiments may be practiced without one or more of these specific details, or with other methods, components, materials, etc. In other instances, well-known structures associated with the technology, such as powertrain components, have not been shown or described in detail to avoid unnecessarily obscuring descriptions of the embodiments. For example, the drawings may include simplified schematic representations of components of the disclosed embodiments to avoid unnecessarily obscuring descriptions of the embodiments.

FIG.1illustrates a vehicle20comprising a wheel46, a wheel well42, and a fender44. The fender44surrounds the wheel well42, and the wheel46is positioned within the wheel well42. A tire48is mounted on the wheel46. The tire48has a ground contact surface50that has a tread. The ground contact surface50is configured to, in operation, contact a ground surface that the vehicle20is driven on. For example, the ground surface may be dirt, gravel, asphalt, concrete, or some other material that acts as a road or is driven on. The wheel46is mounted to an axle of the vehicle20by a plurality of fasteners52, which may include threaded bolts or wheel studs. For example, in some embodiments, a wheel hub assembly is rigidly coupled to a terminal end portion of an axle, such that the wheel hub assembly cannot move or rotate with respect to the axle. Such a connection may be made using, for example, splined teeth. Further, the wheel46is bolted or otherwise rigidly coupled to the wheel hub assembly, such as by the fasteners52, such that the wheel46cannot move or rotate with respect to either the wheel hub assembly or the axle. The axle, in this description, may be a drive axle that is driven to rotate with respect to a body of the vehicle20by an engine or motor mounted within the body of the vehicle20.

FIGS.2A and2Billustrate a planetary gear set or planetary gear train100. As illustrated inFIGS.2A and2B, a planetary gear set100may include a hollow and generally cylindrical outer ring gear130. As illustrated inFIGS.2A and2B, the ring gear130has an overall cylindrical shape that extends along a central longitudinal axis102of the planetary gear set100, and has a cylindrical open internal space that extends along the central longitudinal axis102. As also illustrated inFIGS.2A and2B, the ring gear130has a generally cylindrical internal surface132. As illustrated inFIGS.2A and2B, the internal surface132of the ring gear130includes a set of inward-facing inner gear teeth. The set of inner gear teeth of the ring gear130mate with and engage with other gear teeth of other gears of the planetary gear set100.

As illustrated inFIGS.2A and2B, the planetary gear set100further includes, in addition to the outer ring gear130, a sun gear138having, and rotatable about, a central longitudinal axis coincident with the central longitudinal axis102of the planetary gear set100, a set of four planet gears140spaced equidistantly apart from one another about the sun gear138and each having, and rotatable about, a respective central longitudinal axis parallel to and offset from the central longitudinal axis102of the planetary gear set100, and a gear carrier142having, and rotatable about, a central longitudinal axis coincident with the central longitudinal axis102of the planetary gear set100. Each of the planet gears140has external gear teeth meshed with the internal gear teeth of the outer ring gear130, and the sun gear138has external gear teeth meshed with the external gear teeth of each of the planet gears140. Thus, the gears of the planetary gear set100are engaged and meshed with one another such that rotation of the sun gear138about the central longitudinal axis102relative to the outer ring gear130(which is equivalent in this sense to rotation of the outer ring gear130about the central longitudinal axis102relative to the sun gear138) drives each of the planet gears140to rotate about their own central longitudinal axis as well as to orbit the sun gear138.

FIGS.2A and2Billustrate that the gear carrier142includes a generally plate-shaped disc that may have a generally cruciform shape, the cruciform shape formed at least in part by four lobes143of the gear carrier142, where each lobe of the cruciform shape carries a respective peg, pin, or shaft145that extends outward from a major surface of the main body of the gear carrier142along respective axes parallel to and offset from the central longitudinal axis102of the planetary gear set100toward the planet gears140. In use, the planet gears140are rotatably mounted onto the shafts145of the gear carrier142such that, as the planet gears140orbit circumferentially as a unit about the sun gear138and the central longitudinal axis102, the gear carrier142is also driven to rotate about the central longitudinal axis102.FIG.2Aillustrates the planetary gear set100in a first configuration.FIG.2Billustrates the planetary gear set100in a second configuration, in which the gear carrier142is rotated 45° clockwise about the central longitudinal axis102relative to its orientation inFIG.2A, the sun gear138is rotated 90 degrees clockwise about the central longitudinal axis102relative to its orientation inFIG.2A, and the ring gear130is in the same orientation about the central longitudinal axis102as illustrated inFIG.2A. That is, the rotational speed of the sun gear138may generally be higher than (e.g., twice) the rotational speed of the gear carrier142.

In some embodiments, the planetary gear set100may be provided at a mechanical connection between an end of a driven axle of a vehicle and a driven wheel of the vehicle, such as to increase a driving torque and decrease a driving speed of the wheel relative to the axle, or to decrease a driving torque and increase a driving speed of the wheel relative to the axle. For example, a driven axle shaft144may be rigidly coupled to the sun gear138, such as by spline teeth, by being formed integrally therewith, etc. Further, the gear carrier142may be rigidly coupled to a driven wheel, such as by spline teeth, being formed integrally therewith, etc. In some embodiments, the gear carrier142may be a component of a wheel hub assembly to which a wheel (e.g., wheel46) or a rim thereof is bolted or otherwise rigidly coupled, such that the wheel46cannot move or rotate with respect to the wheel hub assembly or with respect to the gear carrier142.

For example,FIG.3illustrates a shiftable wheel end reduction200which includes a planetary gear set201similar to the planetary gear set100that is illustrated inFIGS.2A and2B. In particular,FIG.3illustrates an axle body202, which may comprise a hollow, generally cylindrical tube. The axle body202may be rigidly coupled to a frame or chassis of a vehicle, or may be coupled by a suspension of the vehicle to a frame or chassis thereof. In either case, the axle body202may be coupled to the frame or chassis such that it does not undergo continuous, sustained, gross, and/or major movement (e.g., rotation and/or translation) with respect to the frame or chassis, even if the axle body202may undergo temporary, transient, fine, or minor movement (e.g., rotation and/or translation) with respect to the frame and/or chassis.FIG.3further illustrates that a driven axle shaft204, which may be a solid cylindrical rod, extends through an interior of the hollow, generally cylindrical tube of the axle body202. The driven axle shaft204may be driven by an engine or motor of the vehicle to rotate about its own central longitudinal axis with respect to most of the rest of the vehicle of which it is a part, including a body, frame, and/or chassis thereof, as well as with respect to the engine or motor and the axle body202thereof.

As further illustrated inFIG.3, the shiftable wheel end reduction200includes a gear carrier206, which may function in much the same way as the gear carrier142. In addition, the gear carrier206may also be rigidly coupled to a driven wheel of the vehicle, such as by spline teeth, by bolts or wheel studs, by being formed integrally therewith, etc. In some embodiments, the gear carrier206may be a component of a wheel hub assembly to which a wheel (e.g., wheel46) is bolted or otherwise rigidly coupled, such that the wheel46cannot move (e.g., rotate or translate) with respect to the wheel hub assembly or with respect to the gear carrier206. As further illustrated inFIG.3, the gear carrier206(which may function as a wheel hub assembly or a component thereof) is mounted on the axle body202by one or more roller bearings208. Thus, the gear carrier206(and/or wheel hub assembly) may be mounted on the axle body202such that the gear carrier206can rotate freely with respect to the axle body202about a central longitudinal axis210thereof, but cannot otherwise move (that is, translate or rotate about other axes) with respect to the axle body202.

In some cases, the driven axle shaft204may be rigidly mechanically coupled to the gear carrier206(and/or to the wheel hub assembly), such as by spline teeth or by being formed integrally therewith, such that the gear carrier206cannot move (that is, rotate and/or translate) with respect to the driven axle shaft204. In such cases, the gear carrier206and a wheel rigidly coupled thereto are driven to rotate at the same speed and torque as the driven axle shaft204. In other cases, as illustrated inFIG.3, the driven axle shaft204is mechanically coupled to the gear carrier206(and/or to the wheel hub assembly) by the planetary gear set201. In such cases, the gear carrier206and a wheel rigidly coupled thereto can be driven to rotate at different speeds and torques than the driven axle shaft204.

In particular, the driven axle shaft204is rigidly coupled to a sun gear212, such as by spline teeth or by being formed integrally therewith, etc. Further, the gear carrier206is mechanically coupled to a plurality of (e.g., three, four, or five) planet gears214, such as by shafts216. As described with reference toFIGS.2A and2B, each of the shafts216extends outward from a major surface of the main body of the gear carrier206along respective axes parallel to and offset from the central longitudinal axis210toward the planet gears214. In use, the planet gears214are rotatably mounted onto the shafts216of the gear carrier206such that, as the planet gears214orbit circumferentially as a unit about the sun gear212and the central longitudinal axis210, the gear carrier206also rotates about the central longitudinal axis210.

FIG.3also illustrates that the shiftable wheel end reduction200includes a ring gear218that extends circumferentially around the sun gear212and the planet gears214. As described with reference toFIGS.2A and2B, the ring gear218includes internal gear teeth that extend around an inner surface thereof facing towards the sun gear212and the planet gears214. The planet gears214have external gear teeth that mesh with the internal gear teeth of the ring gear218. The sun gear212in turn has external gear teeth that mesh with the external gear teeth of the planet gears214. Thus, the wheel end reduction200and its sun gear212, planet gears214, gear carrier206, and ring gear218function as a planetary gear set201in a manner similar to that described with respect to the planetary gear set100ofFIGS.2A and2B.

FIG.3illustrates that the outer ring gear218has a first, generally cylindrical portion218athat carries its inner gear teeth that mesh with and engage the outer gear teeth of the planet gears214. The outer ring gear218also has a second, generally disc-shaped portion218bthat extends radially inward from the first, generally cylindrical portion218ato adjacent, near, or proximate the driven axle shaft204. The outer ring gear218also has a third, generally cylindrical portion218cthat extends longitudinally from the second, generally disc-shaped portion218binto the axle body202between an inner surface of the axle body202and an outer surface of the driven axle shaft204. The outer ring gear218further includes, at a terminal end portion of the third, generally cylindrical portion218copposite to the first, generally cylindrical portion218a, an engagement feature or mechanism, which may include a pair of circumferential ridges or teeth218dextending circumferentially about an outer surface of the third, generally cylindrical portion218c, and a circumferential groove located between the ridges218d.

Other components of the vehicle of which the shiftable wheel end reduction200is a part may be mechanically engaged with the ridges218dand the groove between them to allow the outer ring gear218to be moved longitudinally inward relative to the axle body202and longitudinally outward relative to the axle body202in directions parallel to the central longitudinal axis210. For example, there may be an opening in a side wall of the axle body202, through which other mechanical components, such as a lever, switch, actuator219, shift fork, etc., may extend to engage with and actuate the ridges218dto move the outer ring gear either inward or outward along the central longitudinal axis210. The other components of the shiftable wheel end reduction200, including the driven axle shaft204, the gear carrier206, the roller bearings208, the sun gear212, and the planet gears214are generally mechanically fixed to the axle body202such that they cannot translate relative thereto. Thus, moving the outer ring gear218longitudinally inward or outward relative to the axle body202also moves the outer ring gear218longitudinally inward or outward, respectively, relative to the driven axle shaft204, the gear carrier206, the roller bearings208, the sun gear212, and the planet gears214.

FIG.3further illustrates that the shiftable wheel end reduction200includes a first engagement mechanism or clutch220and a second engagement mechanism or clutch222. The first and second engagement mechanisms220and222may include any suitable type of clutch or other device that allows selective engagement and disengagement of rotating components. In the embodiment illustrated inFIG.3, the first and second engagement mechanisms220and222each comprise a “positive clutch” or a “dog clutch,” where a first rotating component includes first teeth or dogs that engage with counterpart second teeth or dogs of a second rotating component. In some cases, the teeth or dogs of one of the rotating components may be arranged to form grooves or recesses between the teeth or dogs, where the grooves or recesses are configured to receive the teeth or dogs of the other, counterpart rotating component.

For example, inFIG.3, the first clutch220is composed of a first set of teeth220aand a first set of counterpart recesses220b. The first teeth220aare formed in a terminal distal end surface of the axle body202that faces outward away from the axle body202and toward a wheel coupled to the gear carrier206. The first recesses220bare formed in proximal end surface of the second, generally disc-shaped portion218bof the ring gear218that faces inward toward the axle body202and away from a wheel coupled to the gear carrier206. Thus, the first clutch220is configured to prevent relative rotation between the axle body202and the ring gear218when the first clutch220is engaged, that is, when the first teeth220aare positioned and seated within the first recesses220b, and to allow relative rotation between the axle body202and the ring gear218when the first clutch220is disengaged, that is, when the first teeth220aare not positioned and seated within the first recesses220b.

Similarly, inFIG.3, the second clutch222is composed of a second set of teeth222aand a second set of counterpart recesses222b. The second teeth222aare formed in a terminal distal end surface of the first, generally cylindrical portion218aof the ring gear218that faces outward away from the axle body202and toward a wheel coupled to the gear carrier206. Thus, the ring gear218includes a single body containing two clutch interfaces220b,222a. The second recesses222bare formed in proximal end surface of the gear carrier206that faces inward toward the axle body202and away from a wheel coupled to the gear carrier206. Thus, the second clutch222is configured to prevent relative rotation between the ring gear218and the gear carrier206when the second clutch222is engaged, that is, when the second teeth222aare positioned and seated within the second recesses222b, and to allow relative rotation between the ring gear218and the gear carrier206when the second clutch222is disengaged, that is, when the second teeth222aare not positioned and seated within the second recesses222b.

When a vehicle incorporating the switchable wheel end reduction200is in use, an operator or a control unit of the vehicle can actuate the ring gear218to translate inward along the central longitudinal axis210toward the axle body202and away from a wheel mounted on the gear carrier206, thereby engaging the first clutch220and disengaging the second clutch222such that the ring gear218is rotationally locked to the axle body202, that is, with respect to a body, frame, and/or chassis of the vehicle. In such a configuration, power is carried from an engine or motor of the vehicle, to the driven axle shaft204, to the sun gear212, which is driven to rotate about the central longitudinal axis210. Because the ring gear218is effectively stationary with respect to the vehicle body, frame, and/or chassis, rotation of the sun gear212about the central longitudinal axis210drives the planet gears214to rotate about their own central longitudinal axes on the shafts216and to orbit about the sun gear212and the central longitudinal axis210.

The orbiting of the planet gears214about the central longitudinal axis210, in turn, drives the gear carrier206to rotate about the central longitudinal axis210, at a slower speed and at a higher torque than the sun gear212and the driven axle shaft204. In particular, the rotational speed of the sun gear212may generally be higher than (e.g., twice) the rotational speed of the gear carrier206, and the torque of the sun gear may generally be lower (e.g., half) the torque of the gear carrier206. Rotation of the gear carrier206about the central longitudinal axis210, in turn, drives rotation of a driven wheel of the vehicle coupled to the gear carrier206(which may also function as a wheel hub assembly or a part thereof). Thus, when the first clutch220is engaged, torque supplied by an engine or motor of the vehicle to the driven axle shaft204is increased and transferred by the switchable wheel end reduction200to the wheel.

When a vehicle incorporating the switchable wheel end reduction200is in use, an operator or a control unit of the vehicle can actuate the ring gear to translate outward along the central longitudinal axis210away from the axle body202and toward a wheel mounted on the gear carrier206, thereby disengaging the first clutch220and engaging the second clutch222such that the ring gear218is rotationally locked to the gear carrier206, that is, such that the ring gear218can rotate freely with respect to a body, frame, and/or chassis of the vehicle but cannot rotate with respect to the gear carrier206. Because the ring gear218cannot rotate about the central longitudinal axis210with respect to the gear carrier206, the planetary gear set201of the switchable wheel end reduction200is locked, such that none of the gears thereof can rotate with respect to one another and such that all of the gears thereof rotate in unison. In such a configuration, power is carried from an engine or motor of the vehicle, to the driven axle shaft204, to the sun gear212, which is driven to rotate about the central longitudinal axis210. Because the planetary gear set is locked, rotation of the sun gear212about the central longitudinal axis210drives the rest of the planetary gear set, including the planet gears214, ring gear218, and gear carrier206to rotate in unison and at the same speed about the central longitudinal axis210.

In particular, the entirety of the planetary gear set201rotates about the central longitudinal axis210at the same speed and at the same torque as the sun gear212and the driven axle shaft204. In particular, the rotational speed of the sun gear212may generally be the same as the rotational speed of the gear carrier206, and the torque of the sun gear212may generally be the same as the torque of the gear carrier206. Rotation of the gear carrier206about the central longitudinal axis210, in turn, drives rotation of a driven wheel of the vehicle coupled to the gear carrier206(which may also function as a wheel hub assembly or a part thereof). Thus, when the first clutch220is disengaged and the second clutch222is engaged, torque supplied by an engine or motor of the vehicle to the driven axle shaft204is maintained and transferred by the switchable wheel end reduction200to the wheel.

Thus, the switchable wheel end reduction200allows an operator of a vehicle, or an electronic control unit thereof, to switch between two operating modes: a first operating mode in which mechanical power is supplied to driven wheels of the vehicle at the same rotational speed and torque as the driven axle shaft204, and a second operating mode in which mechanical power is supplied to driven wheels of the vehicle at a lower rotational speed and a higher torque than the driven axle shaft204. In some alternative embodiments, however, the switchable wheel end reduction200may allow an operator of a vehicle, or an electronic control unit thereof, to switch between two operating modes: a first operating mode in which mechanical power is supplied to driven wheels of the vehicle at the same rotational speed and torque as the driven axle shaft204, and a second operating mode in which mechanical power is supplied to driven wheels of the vehicle at a higher rotational speed and a lower torque than the driven axle shaft204.

The wheel end reduction200may be shiftable between exactly these two settings or operating modes. That is, “shiftable,” in this disclosure, indicates that the wheel end reduction200provides a binary choice between, first, maintaining speed and torque through the system, or, second, increasing torque and decreasing speed through the system. In some embodiments, increasing torque and decreasing speed may be by a factor of greater than 2.0, greater than 2.5, greater than 3.0, greater than 3.5, greater than 4.0, or greater than 4.5, and/or less than 2.5, less than 3.0, less than 3.5, less than 4.0, less than 4.5, or less than 5.0. In some embodiments, increasing torque and decreasing speed may be by a factor of 3.5 or about 3.5. Thus, at any moment, either the first clutch220is engaged and the second clutch222is disengaged, or the first clutch220is disengaged and the second clutch222is engaged. At no time is it the case that both the first clutch220and the second clutch222are engaged. Such a configuration, if possible, would rotationally lock the driven wheels to the body, chassis, and/or frame of the vehicle and prevent the vehicle from driving. Similarly, at no time is it the case that both the first clutch220and the second clutch222are disengaged. Such a configuration, if possible, would rotationally disengage the driven wheels from the rest of the vehicle and prevent the vehicle from being driven.

While the first and second clutches220,222, described herein are positive clutches with teeth that are positioned within recesses to engage the clutches, various alternative clutches, such as friction clutches and/or curvic clutches, could be used instead. Further, while the switchable wheel end reduction200can be mechanically actuated by driving the ring gear218to move either longitudinally inward or longitudinally outward, various alternative embodiments could be used. For example, the switchable wheel end reduction200may include a spring or other biasing element that biases the ring gear218into an inward position, in which the first clutch220is engaged and the second clutch222is disengaged, and the switchable wheel end reduction200can be mechanically actuated by driving the ring gear218to move into a longitudinally outward position, in which the first clutch220is disengaged and the second clutch222is engaged. Similarly, the switchable wheel end reduction200may include a spring or other biasing element that biases the ring gear218into an outward position, in which the first clutch220is disengaged and the second clutch222is engaged, and the switchable wheel end reduction200can be mechanically actuated by driving the ring gear218to move into a longitudinally inward position, in which the first clutch220is engaged and the second clutch222is disengaged.

In some embodiments, the shiftable wheel end reduction200can be switched or actuated manually, that is, purely mechanically. For example, a driver or operator of the vehicle of which it is a part may actuate a lever or other mechanical switch to directly, manually, mechanically actuate the shiftable wheel end reduction200between its two operating modes. In other embodiments, the shiftable wheel end reduction200can be switched or actuated manually, that is, by a driver or operator of the vehicle of which it is a part, such as by the driver or operator pushing a button, flipping a switch, etc., which initiates an electrical signal that is communicated, such as by an electronic control unit, to an actuator coupled to the circumferential ridges218d. When the actuator receives the signal, it can mechanically actuate the shiftable wheel end reduction200between its two operating modes. In other embodiments, the shiftable wheel end reduction200can be switched or actuated electronically or automatically, that is, without input from a driver or operator of the vehicle of which it is a part. For example, the vehicle may include a number of sensors and collect a number of streams of data, and based on the output received from the sensors and the streams of data received, the electronic control unit can determine that the shiftable wheel end reduction200should be shifted between its two operating modes and initiate an electrical signal that is communicated to an actuator coupled to the circumferential ridges218d. When the actuator receives the signal, it can mechanically actuate the shiftable wheel end reduction200between its two operating modes.

In some specific examples, the driver or the electronic control unit may determine that, when an internal combustion engine is operating at below a threshold speed in rpm (revolutions per minute), the shiftable wheel end reduction200should be actuated to engage the first clutch220and disengage the second clutch222, and when the internal combustion engine is operating at above the threshold speed in rpm, the shiftable wheel end reduction200should be actuated to disengage the first clutch220and engage the second clutch222. Such a threshold speed may be greater than 800, 900, 1000, 1100, 1200, 1300, or 1400 rpm, and/or less than 1600, 1700, 1800, 1900, 2000, 2100, or 2200 rpm. In some cases, the threshold speed may be 1500 rpm. In other examples, the driver or the electronic control unit may determine that, when a vehicle is travelling at below a threshold speed across the ground surface in mph (miles per hour), the shiftable wheel end reduction200should be actuated to engage the first clutch220and disengage the second clutch222, and when the vehicle is travelling at above the threshold speed in mph, the shiftable wheel end reduction200should be actuated to disengage the first clutch220and engage the second clutch222. Such a threshold speed may be greater than 5, 10, 15, 20, or 25 mph, and/or less than 10, 15, 20, 25, or 30 mph.

In other examples, the driver or the electronic control unit may determine that, when a vehicle (including all cargo and anything being towed) weighs above a threshold weight, the shiftable wheel end reduction200should be actuated to engage the first clutch220and disengage the second clutch222, and when the vehicle weighs below the threshold weight, the shiftable wheel end reduction200should be actuated to disengage the first clutch220and engage the second clutch222. In other examples, the driver or the electronic control unit may determine that, when a vehicle is traversing a ground surface at an angle above a threshold grade, the shiftable wheel end reduction200should be actuated to engage the first clutch220and disengage the second clutch222, and when the vehicle is traversing a ground surface at an angle below the threshold grade, the shiftable wheel end reduction200should be actuated to disengage the first clutch220and engage the second clutch222.

In other examples, the driver or the electronic control unit may determine that, when the vehicle is underperforming in terms of power, speed, acceleration, etc., relative to performance demanded by the driver, the shiftable wheel end reduction200should be actuated to engage the first clutch220and disengage the second clutch222, and when the vehicle is performing or overperforming relative to performance demanded by the driver, the shiftable wheel end reduction200should be actuated to disengage the first clutch220and engage the second clutch222. In other examples, any number of the aforementioned factors may be used in combination with one another to determine when the shiftable wheel end reduction200should be actuated to engage the first clutch220and disengage the second clutch222, and when the shiftable wheel end reduction200should be actuated to disengage the first clutch220and engage the second clutch222.

The present disclosure has primarily illustrated and discussed one driven axle shaft, one wheel, and one shiftable wheel end reduction connecting the driven axle shaft to the wheel. In practice, many wheeled vehicles such as automobiles have at least two axle shafts, with at least two wheels mounted at opposite ends of each of the axle shafts. Thus, the features described herein for the switchable wheel end reduction200may be provided for two wheels at opposite ends of a driven axle shaft. Further, the features described herein for the switchable wheel end reduction200may be provided for two wheels at opposite ends of each of two driven axle shafts. In general, the features described herein for the switchable wheel end reduction200may be provided for any number of driven wheels mounted on any number of driven axle shafts. In some embodiments where a vehicle has multiple switchable wheel end reductions as described herein, each of the shiftable wheel end reductions may be independently controllable such that they can be actuated between their operating modes independently. In other embodiments where a vehicle has multiple switchable wheel end reductions as described herein, each of the shiftable wheel end reductions may be controllable as a unit rather than independently, such that they can be actuated to switch between their operating modes in unison or simultaneously.

The shiftable wheel end reduction described herein provides various advantages. For example, the shiftable wheel end reduction allows the driven wheels of a vehicle to be operated in two different operating modes: a first relatively high-torque and low-speed operating mode and a second relatively low-torque and high-speed operating mode. By providing these mechanical components adjacent to the driven wheels rather than elsewhere in the power train, most of the components of the power train can be made smaller and more efficiently because they can be designed for relatively high speeds and relatively low torque loads, while still being able to provide a larger torque to the wheels. This can free up valuable space throughout the power train and reduce overall costs. Because torque is increased at the shiftable wheel end reduction primarily at low operating speeds, there is little cost associated with increased speed of components in the power train when the shiftable wheel end reduction is increasing the torque.

Using the switchable wheel end reduction200to increase torque is associated with some energy losses to friction within the planetary gear set, which can also result in generation of waste heat. Thus, the switchable wheel end reduction200may be provided with a lubricant and/or a coolant to reduce friction losses and mitigate heat generation. In some cases, a pump, such as a gerotor pump, may be provided, for example, between the sun gear212and the gear carrier206, which can be automatically actuated to operate and pump the lubricant and/or coolant when the switchable wheel end reduction is increasing torque and which can be automatically actuated to not operate and not pump the lubricant and/or coolant when the switchable wheel end reduction is not increasing torque.

The technologies described herein may be used in any wheeled vehicle, such as passenger vehicles, trucks, heavy-duty trucks, etc., and with any motors or engines, including internal combustion engines, including diesel engines. The technologies described herein may be particularly useful, however, in electric vehicles driven by electric motors or other electric propulsion units, at least because electric powertrains typically have an advantage in reaction speed and can therefore more quickly synchronize the clutches with electric motor(s).

Aspects of the various embodiments described above can be combined to provide further embodiments. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled.