Abstract:
A driveline component with a housing, a pinion mounted in the housing for rotation about a first axis, a ring gear and a pair of output members. The ring gear is meshed with the pinion and is rotatable about a second axis. The ring gear is supported for rotation relative to the housing by a pair of tapered roller bearings that are disposed along the second axis on a common lateral side of the ring gear. The output members are drivingly coupled to the ring gear.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 14/239,756 filed Feb. 19, 2014, which is a U.S. National Phase application under 35 U.S.C. §371 of International Application No. PCT/US2013/063219, filed on Oct. 3, 2013, which claims the benefit and priority of U.S. 61/710,007, filed on Oct. 5, 2012. The entire disclosure of each of the above applications is incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present disclosure relates to single speed and two-speed disconnecting axle arrangements. 
       BACKGROUND 
       [0003]    This section provides background information related to the present disclosure which is not necessarily prior art. 
         [0004]    Many modern automotive vehicles, such as crossover vehicles, are available with an all-wheel drive (AWD) drivetrain that is based on a front-wheel drive (FWD) architecture. This optional drivetrain arrangement permits drive torque to be selectively and/or automatically transferred from the powertrain to both the primary (i.e., front) driveline and the secondary (i.e., rear) driveline to provide better traction when the vehicle is operated in inclement weather and on off-highway road conditions. Such AWD vehicles necessarily are equipped with a much more complex drivetrain which, in addition to the primary driveline, must include the additional components associated with the secondary driveline such as a power take-off unit and a propshaft. 
         [0005]    In an effort to minimize driveline losses (i.e., viscous drag, friction, inertia and oil churning) associated with secondary driveline being back-driven when no drive torque is transmitted thereto, it is known to incorporate a disconnect system that is configured to uncouple components of the secondary driveline such as, for example, the rear wheels or the rear differential from the remainder of the secondary driveline. To this end, there remains a need in the art for development of improved disconnectable drivelines for use in AWD vehicles. 
       SUMMARY 
       [0006]    This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
         [0007]    In one form, the present teachings provide a driveline component with a housing, a pinion mounted in the housing for rotation about a first axis, a ring gear and a pair of output members. The ring gear is meshed with the pinion and is rotatable about a second axis. The ring gear is supported for rotation relative to the housing by a pair of tapered roller bearings that are disposed along the second axis on a common lateral side of the ring gear. The output members are drivingly coupled to the ring gear. 
         [0008]    In another form, the present teachings provide a drivetrain for an all-wheel drive motor vehicle. The drivetrain includes a primary driveline, a power switching mechanism and a second driveline. The primary driveline includes a first differential having a first differential case. The primary driveline is configured to drive a pair of first vehicle wheels. The power switching mechanism has an input shaft that is configured to receive rotary power from a powertrain and a disconnect mechanism that can be operated in a connected mode, which permits transmission of rotary power between the input shaft and the output pinion shaft, and a disconnected mode that inhibits transmission of rotary power between the input shaft and the output pinion shaft. The second driveline includes a propshaft and a rear drive module. The rear drive module includes a second differential, an input pinion shaft driving a hypoid gear and a torque transfer device. The second differential has an input member and a pair of output members that are configured to drive a pair of second vehicle wheels. The input pinion shaft is coupled by the propshaft to the output pinion shaft of the power switching mechanism. The torque transfer device is surrounds the planetary gear assembly and includes a clutch input member driven by the hypoid gear, a clutch output member driving the planetary gear assembly, and a clutch pack operably disposed between the input clutch member and the output clutch member. The torque transfer device is operable in a first mode, which permits transmission of rotary power from the clutch input member to the clutch output member, and a second mode that inhibits transmission of rotary power from the clutch input member to the clutch output member. 
         [0009]    Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0010]    The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
           [0011]      FIG. 1  is a schematic of a motor vehicle equipped with a disconnectable all-wheel drive system constructed in accordance with the present teachings; 
           [0012]      FIG. 2  is a schematic illustration of a single-speed power take-off unit associated with the disconnectable all-wheel drive system of  FIG. 1 ; 
           [0013]      FIG. 3  through  FIG. 5  are perspective views of a single-speed power take-off unit based on the schematic shown in  FIG. 2  with its housing structure removed for improved clarity and which is constructed in accordance with the present teachings; 
           [0014]      FIG. 6  is a sectional view of the single-speed power take-off unit taken generally along line  6 - 6  of  FIG. 5 ; 
           [0015]      FIG. 7  is a schematic illustration of a single-speed rear drive module associated with the disconnectable all-wheel drive system of  FIG. 1 ; 
           [0016]      FIG. 8  is a sectional view of a single-speed rear drive module based on the schematic shown in  FIG. 7  and which is constructed in accordance with the present teachings; 
           [0017]      FIG. 9  is a sectional view of another single-speed rear drive module constructed in accordance with the present teachings and which can also be associated with the disconnectable all-wheel drive system of  FIG. 1 ; 
           [0018]      FIG. 10  is a schematic of a motor vehicle equipped with another configuration of a disconnectable all-wheel drive system constructed in accordance with the present teachings; 
           [0019]      FIG. 11  is a schematic illustration of a two-speed power take-off unit associated with the disconnectable all-wheel drive system of  FIG. 10 ; 
           [0020]      FIG. 12  is an exploded perspective view of a two-speed power take-off unit based on the schematic shown in  FIG. 11  and which is constructed in accordance with the present teachings; 
           [0021]      FIG. 13  is a sectional view of the two-speed power take-off unit shown in  FIG. 11 ; 
           [0022]      FIGS. 14A through 14D  are partial sectional views of the two-speed power take-off unit shown in  FIG. 13  with its mode and range shift components positioned to define a two-wheel high-range (2-Hi) mode, a four-wheel high-range (4-Hi) mode, a neutral mode, and a four-wheel low-range (4-Low) mode, respectively; 
           [0023]      FIG. 15  is a schematic illustration of a two-speed rear drive module associated with the disconnectable all-wheel drive system of  FIG. 10 ; 
           [0024]      FIGS. 16A through 16C  are sectional views of a two-speed rear drive module based on the schematic shown in  FIG. 15  with its range shift components positioned to define a high-range (H) mode, a neutral (N) mode, and a low-range (L) mode; and 
           [0025]      FIG. 17  is a schematic of another two-speed rear drive module associated with the disconnectable all-wheel drive system of  FIG. 10 . 
       
    
    
       [0026]    Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
       DETAILED DESCRIPTION 
       [0027]    The following exemplary embodiments are provided so that the present disclosure will be thorough and fully convey the scope to those skilled in the art. Numerous specific details are set forth such as examples of specific components, devices and schematic configurations to provide a thorough understanding of exemplary embodiments of the present disclosure. However, it will be apparent to those skilled in the art that these specific details need not be employed, that the exemplary embodiments may be embodied in many different forms, and that neither should be construed to limit the scope of the present disclosure. 
         [0028]    With reference to  FIG. 1  of the drawings, a motor vehicle constructed in accordance with the teachings of the present disclosure is schematically shown and generally indicated by reference numeral  10 . The vehicle  10  can include a powertrain  12  and a drivetrain  14  that can include a primary driveline  16 , a power switching mechanism  18 , a secondary driveline  20 , and a control system  22 . In the various aspects of the present teachings, the primary driveline  16  can be a front driveline while the secondary driveline  20  can be a rear driveline. 
         [0029]    The powertrain  12  can include a prime mover  24 , such as an internal combustion engine or an electric motor, and a transmission  26  which can be any type of ratio-changing mechanism, such as a manual, automatic, or continuously variable transmission. The prime mover  24  is operable to provide rotary power to the primary driveline  16  and the power transfer mechanism  18 . 
         [0030]    With additional reference to  FIG. 2 , the primary driveline  16  can include a primary or first differential  30  having an input member  32  driven by an output member (not shown) of the transmission  26 . In the particular construction shown, the first differential  30  is configured as part of the transmission  26 , a type commonly referred to as a transaxle and typically used in front-wheel drive vehicles. The primary driveline  16  can further include a pair of first axle shafts  34 L,  34 R that can couple output components of the first differential  30  to a set of first vehicle wheels  36 L,  36 R. The first differential  30  can include a first differential case  38  that is rotatably driven by the input member  32 , at least one pair of first pinion gears  40  rotatably driven by the first differential case  38 , and a pair of first output side gears  42  meshed with the first pinion gears  40  and which are connected to drive the first axle shafts  34 L,  34 R. 
         [0031]    With continued reference to  FIG. 2 , the power switching mechanism  18 , hereinafter referred to as a power take-off unit (PTU), can generally include a housing  46 , an input  48  coupled for common rotation with the first differential case  38  of the first differential  30 , an output  50 , a transfer gear assembly  52 , a disconnect mechanism  54 , and a disconnect actuator  56 . The input  48  can include a tubular input shaft  58  rotatably supported by the housing  46  and which concentrically surrounds a portion of the first axle shaft  34 R. A first end of the input shaft  58  can be coupled for rotation with the first differential case  38 . The output  50  can include an output pinion shaft  60  rotatably supported by the housing  46  and having a pinion gear  62 . The transfer gear assembly  52  can include a hollow transfer shaft  64 , a helical gearset  66 , and a hypoid gear  68  that is meshed with the pinion gear  62 . The transfer shaft  64  concentrically surrounds a portion of the first axle shaft  34 R and is rotatably supported by the housing  46 . The helical gearset  66  can include a first helical gear  70  fixed for rotation with the transfer shaft  64  and a second helical gear  72  which is meshed with the first helical gear  70 . The second helical gear  72  and the hypoid gear  68  are integrally formed on, or fixed for common rotation with, a stub shaft  74  that is rotatably supported in the housing  46 . 
         [0032]    The disconnect mechanism  54  can comprise any type of clutch, disconnect or coupling device that can be employed to selectively transmit rotary power from the powertrain  14  to the secondary driveline  20 . In the particular example provided, the disconnect mechanism  54  is configured as a dog clutch. The dog clutch can include a set of external spline teeth  76  formed on a second end of the input shaft  58 , a set of external clutch teeth  78  formed on the transfer shaft  64 , a mode collar  80  having internal spline teeth  82  constantly meshed with the external spline teeth  76  on the input shaft  58 , and a shift fork  84  operable to axially translate the shift collar  80  between a first mode position and a second mode position. While schematically shown as a non-synchronized dog clutch, it will be understood that the disconnect mechanism  54  can include a synchronized dog clutch if such a configuration is desired. 
         [0033]    The mode collar  80  is shown in its first mode position, identified by a “2WD” leadline, wherein the internal spline teeth  82  on the mode collar  80  are disengaged from the external clutch teeth  78  on the transfer shaft  64 . As such, the input shaft  58  is disconnected from driven engagement with the transfer shaft  64 . Thus, no rotary power is transmitted from the powertrain  12  to the transfer gear assembly  52  and the output pinion shaft  60  of the power take-off unit  18 . With the mode collar  80  in its second mode position, identified by an “AWD” leadline, its internal spline teeth  82  are engaged with both the external spline teeth  76  on the input shaft  58  and the external clutch teeth  78  on the transfer shaft  64 . Accordingly, the mode collar  80  establishes a drive connection between the input shaft  58  and the transfer shaft  64  such that rotary power from the powertrain  12  is transmitted through the power take-off unit  18  to the output pinion shaft  60 . As will be detailed, the output pinion shaft  60  is coupled via a propshaft  86  to the secondary driveline  20 . 
         [0034]    The disconnect actuator  56  can be any type of actuator mechanism that is operable for axially moving the shift fork  84  which, in turn, causes concurrent axial translation of the mode collar  80  between its two distinct mode positions. The disconnect actuator  56  is shown mounted to the housing  46  of the power take-off unit  18 . The disconnect actuator  56  can be a power-operated mechanism that can receive control signals from the control system  22  and can include, for example, hydraulically-actuated, pneumatically-actuated or electromechanically-actuated arrangements. 
         [0035]    As noted,  FIG. 2  schematically illustrates the components that can be associated with the power take-off unit  18 . Reference now to  FIG. 3 through 6  will provide a more definitive structural configuration of such components that are associated with an exemplary embodiment of the power take-off unit  18 . In particular, these drawings illustrate the components in an assembled condition with the housing  46  removed for improved clarity. Each of the input shaft  58 , the transfer shaft  64 , the stub shaft  74 , and the output pinion shaft  60  are shown with suitable bearings assembled thereon for rotatably supporting each within or from the housing  46 . The disconnect actuator  56  is shown as a self-contained power-operated unit  88  from which the shift fork  84  extends. The power-operated unit  88  can include an electric motor and a geared drive unit configured to convert rotation of the motor output into translational movement of the shift fork  84 . External spline teeth  90  are provided on one end of the first axle shaft  34 R for facilitating a splined connection with its respective first side gear  42  in the first differential  30 . Likewise, external spline teeth  92  are provided on the first end of the input shaft  58  for facilitating a splined connection with a mating portion of the first differential case  38 . 
         [0036]    With particular reference now to  FIGS. 1 and 7 , the secondary driveline  20  can include the propshaft  86 , a rear drive module (RDM)  100 , a pair of second axle shafts  102 L,  102 R, and a pair of second vehicle wheels  104 L,  104 R. A first end of the propshaft  86  can be coupled for rotation with the output pinion shaft  60  extending from the power take-off unit  18  while a second end of the propshaft  86  can be coupled for rotation with an input assembly  106  of the rear drive module  100 . The rear drive module  100  can include a housing  108 , a secondary or second differential  110 , a torque transfer device (TTD)  112  that is generally configured and arranged to selectively couple and transmit rotary power from the input assembly  106  to the second differential  110 , and a TTD actuator  114 . The input assembly  106  can include an input pinion shaft  116  having a pinion gear  118 , a hollow spool  120 , and a hypoid gear  122  fixed for rotation with the spool  120  and which is meshed with the pinion gear  118 . The second differential  110  can include an input member such as a second differential case  124 , at least one pair of second pinion gears  126  rotatably driven by the second differential case  124 , and a pair of output members such as second output side gears  128  that are meshed with the second pinion gears  126 . The second output side gears  128  are fixed for rotation with the inboard ends of the second axle shafts  102 L,  102 R. The second differential  110  and the torque transfer device  112  are shown disposed on one side of the input pinion shaft  116  to provide a compact arrangement. 
         [0037]    The torque transfer device  112  can include any type of clutch or coupling device that can be employed to selectively transmit rotary power from the input assembly  106  to the second differential  110 . In the example shown, the torque transfer device  112  is a multi-plate friction clutch that can include an input clutch member  130  driven by the hypoid gear  122 , an output clutch member  132  coupled for rotation with the second differential case  124 , a multi-plate clutch pack  134  having a plurality of interleaved friction plates disposed between the input and output clutch members, and an engagement member  136  that is moveable for selectively applying a clutch engagement force to the clutch pack  134 . The torque transfer device  112  is shown to generally surround a portion of the second differential  110 . The TTD actuator  114  is provided to generate translational movement of the engagement member  136  relative to the clutch pack  134  and can be controlled by control signals from the control system  22 . 
         [0038]    A first or “disconnected” mode can be established for the torque transfer device  112  when the engagement member  136  is positioned such that rotary power is not transmitted from the input clutch member  130  to the output clutch member  132 . In this “disconnected” mode, the second vehicle wheels  104 L,  104 R, the second axle shafts  102 L,  102 R, the second differential  110 , and the output clutch member  132  are disconnected from the input  106  of the rear drive module  100 . As such, rotation of these components as a result of rolling motion of the second vehicle wheels  104 L,  104 R does not “back-drive” input pinion shaft  116 , the propshaft  86  and components of the power take-off unit  18 . 
         [0039]    A second or “connected” mode for the torque transfer device  112  can be established when the clutch engagement force exerted by the engagement member  136  on the clutch pack  134  causes rotary power to be transmitted from the input  106  to the second differential case  124  for delivery to the second vehicle wheels  104 L,  104 R through the second differential  110 . In addition, a “torque biasing” function can also be provided in the connected mode since variable control over the magnitude of the clutch engagement force applied to the clutch pack  134  can vary the distribution ratio of the rotary power transmitted from the powertrain  12  to the primary driveline  16  and the secondary driveline  20 . Thus, the torque transfer device  112  can be configured or controlled to slip or cyclically engage and disengage as appropriate for biasing the available drive torque while establishing the drive connection between the input  106  and the second differential  110 . 
         [0040]    The TTD actuator  114  can be any power-operated device capable of shifting the torque transfer device  112  between its first and second modes as well as adaptively regulating the magnitude of the clutch engagement force exerted by the engagement member  136  on the clutch pack  134 . Thus, the TTD actuator  114  can, for example, include an electromagnetic or motor-driven ballscrew, ballramp or other cam actuation system having a mechanical connection, shown by lead line  140 , with the engagement member  136 . Alternatively, the TTD actuator  114  can include a hydraulic actuation system capable of regulating the position of the engagement member  136  relative to the clutch pack  134  by regulating fluid pressure, also indicated by lead line  140 , that is delivered to a pressure chamber. 
         [0041]    The control system  22  is schematically shown in  FIG. 1  to include a controller  150 , a group of first sensors  152 , and a group of second sensors  154 . The group of first sensors  152  can be arranged within the motor vehicle  10  to sense a vehicle parameter and responsively generate a first sensor signal. The vehicle parameter can be associated with any combination of the following: vehicle speed, yaw rate, steering angle, engine torque, wheel speeds, shaft speeds, lateral acceleration, longitudinal acceleration, throttle position and gear position without limitations thereto. The group of second sensors  154  can be configured to sense a driver-initiated input to one or more on-board devices and/or systems within the vehicle  10  and responsively generate a second sensor signal. For example, the motor vehicle  10  may be equipped with a sensor associated with a mode selection device, such as a switch associated with a push button or a lever, that senses when the vehicle operator has selected between vehicle operation in a two-wheel drive (FWD) mode and an all-wheel drive (AWD) mode. Also, switched actuation of vehicular systems such as the windshield wipers, the defroster, and/or the heating system, for example, may be used by the controller  150  to assess whether the motor vehicle  10  should be shifted automatically between the FWD and AWD modes. 
         [0042]    As noted,  FIG. 7  schematically illustrates the components that can be associated with the rear drive module  100 . Referring now to  FIG. 8 , a more definitive structural configuration of such components associated with an exemplary embodiment of the rear drive module  100  is shown. Specifically, the hypoid gear  122  can be fixed to a radial flange portion  156  of the bell-shaped spool  120  which, in turn, is rotatably supported from the housing  108  by a pair of laterally-spaced bearing assemblies  158 . A threaded nut  160  is installed on a threaded portion of the spool  120  and can be axially adjusted for varying the preload applied to the bearing assemblies  158 . The second differential case  124  has a hub extension  162  that can be rotatably supported within an enlarged bell portion  164  of the spool  120 . The input clutch member  130  can be operably associated with the hypoid gear  122  and can include a cylindrical clutch drum  166  that is fixed to or integrally formed with the hypoid gear  122 . The output clutch member  132  can be associated with the second differential case  124  and can include a clutch hub  168  that is fixed to or integrally formed on an outer surface of the second differential case  124 . A set of inner clutch plates of the clutch pack  134  can be splined to the clutch hub  168  while a set of outer clutch plates can be splined to the clutch drum  166 . As noted, the torque transfer device  112  is configured to surround a portion of the second differential  110  to provide a compact arrangement. The engagement member  136  can include an apply piston  170  assembly operably disposed for sliding movement in a pressure chamber  172  and which can be supplied with pressurized fluid by a hydraulically-operated unit associated with TTD actuator  114 . 
         [0043]    Referring to  FIG. 9 , an alternative exemplary embodiment for the rear drive module  100  is shown and identified by reference numeral  100 A. The rear drive module  100 A is generally similar to rear drive module  100  but is equipped with an epicyclic-type second differential  110 A in place of the bevel-type second differential  110  shown in  FIGS. 7 and 8 . The epicyclic second differential  110 A can include an annulus gear  180 , a sun gear  182 , a set of first planet gears  184 , a set of the second planet gears  186 , and a carrier unit  188  from which the first planet gears  184  and second planet gears  186  are rotatably supported. The first planet gears  184  can be meshed with the annulus gear  180  while the second planet gears  186  can be meshed with the sun gear  182 . The first and second planet gears are circumferentially arranged such that each one of the first planet gears  184  also meshes with at least one of the second planet gears  186 . The annulus gear  180  acts as the input member for the second differential  110 A while the carrier unit  188  and the sun gear  182  act as the pair of output members. The carrier unit  188  can include a tubular boss  190  that is rotatably supported within the bell portion  164  of the spool  120  and which has a set of internal splines  192  configured to mate with a set of external splines (not shown) formed on an inboard end of the second axle shaft  102 R. Likewise, the sun gear  182  can have a set of internal splines  194  configured to mate with a set of external splines (not shown) formed on an inboard end of the second axle shaft  102 L. 
         [0044]    The torque transfer device  112 A associated with the second differential  110 A can include a clutch drum  166 A fixed for rotation with the hypoid gear  122 , a clutch hub  168 A fixed for rotation with the annulus gear  180 , a clutch pack  134 A operably disposed therebetween, and a clutch engagement member  136 A operable to exert a clutch engagement force on the clutch pack  134 A in response to control signals transmitted by the control system  22  to the TTD actuator  114 . Thus, any rotary power transmitted by the input  106  through the clutch pack  134 A will drive the annulus gear  180  and be transmitted to the second axle shafts  102 L,  102 R through the sun gear  182  and the carrier unit  186 , respectively, while the meshed pairs of the first planet gears  184  and the second planet gears  186  facilitate speed differentiation between the second vehicle wheels  104 L,  104 R. 
         [0045]    With reference to  FIGS. 1 ,  2  and  7 , the vehicle  10  can normally be operated in the two-wheel drive (FWD) mode in which the power take-off unit  18  and the rear drive module  100  are both disengaged. Specifically, the mode collar  80  of the disconnect mechanism  54  is positioned by the disconnect actuator  56  in its first mode position such that the input shaft  58  is uncoupled from the transfer shaft  64 . As such, substantially all power provided by the powertrain  12  is transmitted to the primary driveline  16 . Likewise, the torque transfer device  112  can be shifted into and maintained in its first mode such that the input  106 , the propshaft  86 , the output pinion shaft  60  and the transfer gear assembly  52  within the power take-off unit  18  are not back-driven due to rolling movement of the second vehicle wheels  104 . 
         [0046]    When it is desired or necessary to operate the motor vehicle  10  in the all-wheel drive (AWD) mode, the control system  22  can be activated via a suitable input which, as noted, can include a drive requested input (via the mode select device) and/or an input generated by the controller  150  in response to signals from the first sensors  152  and/or the second sensors  154 . The controller  150  initially signals the TTD actuator  114  to shift the torque transfer device  112  into its second mode. Specifically, the controller  150  controls operation of the TTD actuator  114  such that the actuation member  136  is moved and a clutch engagement force is exerted on the clutch pack  134  that is sufficient to synchronize the speed of the secondary driveline  20  with the speed of the primary driveline  16 . Upon speed synchronization, the controller  150  signals the disconnect actuator  56  to cause the mode collar  80  in the power take-off unit  18  to move from its first mode position into its second mode position. With the mode collar  80  in its second mode position, rotary power is transmitted from the powertrain  12  to the primary driveline  16  and the secondary driveline  20 . It will be appreciated that subsequent control of the magnitude of the clutch engagement force generated by the torque transfer device  112  permits torque biasing across the clutch pack  134  for controlling the torque distribution ratio transmitted from the powertrain  12  to the primary driveline  16  and the secondary driveline  20 . 
         [0047]    With reference to  FIG. 10 , another motor vehicle constructed in accordance with the present teachings is generally indicated by reference numeral  10 ′. The vehicle  10 ′ is generally similar to the vehicle  10  of  FIG. 1  except that the primary driveline  16 ′ and the secondary driveline  20 ′ associated with drivetrain  14 ′ have been modified to incorporate a two-speed range unit into both the power take-off unit  18 ′ and the rear drive module  100 ′. As will be detailed, this alternative drivetrain arrangement for the vehicle  10 ′ permits establishment of at least one all-wheel low range drive mode in addition to the two-wheel high-range drive mode and the all-wheel high-range drive mode associated with vehicle  10 . For purposes of clarity, primed reference numeral are used to designate components that are generally similar in structure and/or function to the non-primed components previously described in relation to  FIGS. 1 through 9 . 
         [0048]    With additional reference now to  FIG. 11 , the power take-off unit  18 ′ is generally shown to include a housing  46 ′, an input  48 ′ adapted for connection to an output member of the transmission  26 ′, an output  50 ′, a transfer gear assembly  52 ′, a first differential  30 ′, a disconnect mechanism  54 ′, a two-speed range unit  198 , and a disconnect actuator  56 ′. The input  48 ′ can include a hollow input shaft  204  rotatably supported by the housing  46 ′ and surrounding the first axle shaft  34 L′. The output  50 ′ can include an output pinion shaft  60 ′ having a pinion gear  62 ′. The transfer gear assembly  52 ′ can include a hollow transfer shaft  64 ′, a helical gearset  66 ′, and a hypoid gear  68 ′ meshed with the pinion gear  62 ′. The helical gearset  66 ′ can include a first helical gear  70 ′ fixed for rotation with the transfer shaft  64 ′ and a second helical gear  72 ′ that is meshed with the first helical gear  70 ′. The second helical gear  72 ′ and the hypoid gear  68 ′ are integral with or fixed to a stub shaft  74 ′ that is rotatably supported by the housing  46 ′. 
         [0049]    The two-speed range unit  198  can include a planetary gear set  200  and a range shift device  202 . The planetary gear set  200  can include a ring gear  206  non-rotatably fixed to the housing  46 ′, a sun gear  208 , a plurality of planet gears  210  meshed with both the ring gear  206  and the sun gear  208 , and a planet carrier  212  from which the planet gears  210  are rotatably supported. The planet carrier  212  is fixed to, or integrally formed with, the first differential case  38 ′ of the first differential  30 ′ for common rotation therewith. 
         [0050]    The range shift device  202  can include a sun gear shaft  220  surrounding a portion of the first axle shaft  34 L′ and which is fixed for rotation with the sun gear  208 , a carrier shaft  222  surrounding a portion of the sun gear shaft  220  and which is fixed for rotation with the planet carrier  212 , and a tubular range sleeve  224  surrounding portions of the carrier shaft  222 , the sun gear shaft  220  and the input shaft  204 . The input shaft  204  can have a first end  226  adapted for connection via a splined coupling shaft  227  ( FIG. 12 ) to the output of transmission  26 ′ and a second end having a set of elongated external spline teeth  228  formed thereon. The range sleeve  224  can include a set of internal spline teeth  230  that are in continuous meshed engagement with the external spline teeth  228  on the input shaft  204 . As such, the range sleeve  224  is coupled for common rotation with the input shaft  204  while being capable of bi-directional axial sliding movement thereon between a plurality of predefined range position which will be discussed hereinafter in greater detail. The range sleeve  224  further defines a set of internal clutch teeth  232  that can be moved into and out of engagement with a set of external clutch teeth  234  formed on the carrier shaft  222  or a set of external clutch teeth  236  formed on the sun gear shaft  220 . 
         [0051]    The disconnect mechanism  54 ′ is generally similar in function to the disconnect mechanism  54  in that it is configured to selectively connect the input shaft  204  to the transfer gear assembly  52 ′ for transmitting rotary power from the input shaft  204  to the output pinion shaft  60 ′ when the all-wheel drive mode is desired. However, the disconnect mechanism  54 ′ differs in that the drive connection between the input shaft  204  and the transfer shaft  64 ′ is made indirectly via the range sleeve  224 . In particular, the range sleeve  224  can include first and second sets of external spline teeth  240  and  242 , respectively, which are selectably engageable with internal spline teeth  244  formed on a mode collar  246 . As such, the mode collar  246  is coupled for rotation with the range sleeve  224  and is capable of bi-directional axial translation relative to the range sleeve  224  between a first (2WD) mode position and a second (AWD) mode position. 
         [0052]    With the mode collar  246  in its first mode position, a set of internal clutch teeth  248  formed on the mode collar  246  are released from meshed engagement with the external clutch teeth  78 ′ on the transfer shaft  64 ′, whereby no rotary power is transmitted from the input shaft  204  through the transfer gear assembly  52 ′ to the output pinion shaft  60 ′. In contrast, with the mode collar  246  in its second mode position, its internal spline teeth  244  are engaged with one of the first and second sets of external splines  240  and  242  (depending on the axial position of the range sleeve  224 ) and its internal clutch teeth  248  are engaged with the clutch teeth  78 ′ on the transfer shaft  64 ′, thereby establishing a drive connection between the input shaft  204  and the output pinion shaft  60 ′. 
         [0053]    The two-speed range unit  198  is operable to establish at least two different speed ratio drive connections between the input shaft  204  and the first differential  30 ′. Specifically, the range sleeve  224  can be axially translated between a plurality of predefined range positions. In a first or “high” (Hi) range position, the range sleeve  224  is located such that its internal clutch teeth  232  are engaged with the external clutch teeth  234  on the carrier shaft  222 . Since the internal splines  230  on the range sleeve  224  remain in constant meshed engagement with the external spline teeth  228  on the input shaft  204 , location of the range sleeve  224  in its high-range position results in establishing a first or direct ratio drive connection between the input shaft  204  and the carrier shaft  222  which, in turn, is connected via the carrier  212  to the first differential case  38 ′. As such, a one-to-one or direct drive connection is established between the input shaft  204  and the first differential  30 ′. 
         [0054]    In a second or “neutral” range position, the range sleeve  224  is disconnected from driven connection with both of the carrier shaft  222  and the sun gear shaft  220  such that the input shaft  204  is disconnect from the first differential  30 ′. 
         [0055]    In a third or “low” (Low) range position, the range sleeve  224  is located such that its internal clutch teeth  232  are engaged with the external clutch teeth  236  formed on the sun gear shaft  220 . With the range sleeve  224  located in its low-range position, a second or reduced-ratio drive connection is established between the input shaft  204  and the first differential  30 ′. Specifically, driven rotation of the sun gear shaft  220  causes the planetary gear set  200  to drive the carrier  212  at a reduced speed relative to the input shaft  204  such that the primary driveline  16 ′ is likewise driven at the reduced speed ratio via the first differential  30 ′. 
         [0056]    With continued reference to  FIG. 11 , the disconnect actuator  56 ′ is shown positioned adjacent to the housing  46 ′ and can include a first shift fork  84 ′ engaging the mode collar  246 , a second shift fork  250  engaging the range sleeve  224 , and a power-operated unit  252  configured to receive control signals from the controller  150  and operable to coordinate movement of the shift forks  84 ′ and  250 . The power-operated unit  252  can be any type of unit capable of selectively translating the first shift fork  84 ′ for causing movement of the mode collar  246  between its two mode positions while also selectively translating the second shift fork  250  for causing movement of the range sleeve  224  between its three range positions. 
         [0057]    With reference now to  FIGS. 12 and 13 , a more definitive structural configuration of the components associated with the two-speed power take-off unit  18 ′ is shown. In particular,  FIG. 12  illustrates an exploded perspective view of an exemplary embodiment of the two-speed power take-off unit  18 ′. Housing  46 ′ is shown to include a multi-piece assembly having a main housing  258  to which a differential housing  260  and a PTU housing  262  are secured.  FIG. 13  is a sectional view which illustrates the compact arrangement of the planetary gear set  200 , the range shift device  202 , the transfer gear assembly  52 ′, and the moveable mode collar  246  and range sleeve  224 . 
         [0058]    As will be understood, the bi-directional translational movement of the range sleeve  224  and the mode collar  246  can be coordinated to establish a plurality of range and mode combinations for the two-speed power take-off unit  18 ′ based on control signals from the controller  150 . Referring to  FIGS. 14A through 14D , these various range and mode combinations can be more clearly illustrated. 
         [0059]      FIG. 14A  shows the positions of the range sleeve  224  and the mode collar  246  for establishing a two-wheel high-range (2-Hi) mode for the power take-off unit  18 ′. Specifically, the mode collar  246  is shown located in its first mode position while the range sleeve  224  is shown located in its first range position. As such, the input shaft  204  is coupled via the range sleeve  224  to the carrier shaft  222  for establishing the direct drive connection between the powertrain  12  and the primary driveline  16 ′. Concurrently, the transfer shaft  64 ′ is disconnected from driven connection with the input shaft  204 , thereby disconnecting the secondary driveline  20 ′ from the powertrain  12 . Thus, rotary power is only transmitted by the powertrain  12  to the primary driveline  16 ′ without speed reduction. 
         [0060]      FIG. 14B  shows the positions of the range sleeve  224  and the mode collar  246  for establishing a four-wheel high-range (4-Hi) mode for the power take-off unit  18 ′. Specifically, the high-range connection is maintained by the range sleeve  224  remaining in its first range position while the mode collar  246  is shown moved into its second mode position. Thus, the mode collar  246  establishes a drive connection from the input shaft  204  (through the range sleeve  224 ) to the transfer shaft  64 ′ for also transmitting rotary power from the powertrain  12  to the secondary driveline  20 ′. 
         [0061]      FIG. 14C  shows the positions of the range sleeve  224  and the mode collar  246  for establishing a Neutral non-driven mode for the power take-off unit  18 ′. As seen, the mode collar  246  is maintained in its second mode position while the range sleeve  224  has been axially moved into its second range position such that its internal splines  232  are disengaged from the external clutch teeth  234  on the carrier shaft  220  and the external clutch teeth  236  on the sun gear shaft  220 . Thus, the input shaft  204  is disconnected from both inputs to the primary driveline  16 ′ such that no rotary power is transmitted from the powertrain  12  to the primary driveline  16 ′. It will also be noted that such movement of the range sleeve  224  to its second range position causes the internal spline teeth  244  on the mode collar  246  to disengage the first set of external splines  240  on the range sleeve  224  while the mode collar  246  maintains its connection with the transfer shaft  64 ′. 
         [0062]      FIG. 14D  shows the position of the mode collar  246  and the range sleeve  224  for establishing a four-wheel low-range (4-Low) mode for the power take-off unit  18 ′. Specifically, the mode collar  246  is maintained in its second mode position while the range sleeve  224  is moved axially into its third range position. As such, the low-range drive connection is established by the range sleeve  224  between the input shaft  204  and the sun gear shaft  220  while the AWD connection is established by the mode collar  246 . It will be noted that the internal spline teeth  244  of the mode collar  246  engage the second set of external spline teeth  242  upon movement of the range sleeve  224  from its neutral range position into its low range position. While it is possible to provide the external splines  240  and  242  on the range sleeve  224  in a continuous arrangement, the non-toothed separation space therebetween has been recognized to inhibit potential tooth blocking conditions upon movement of the range sleeve  224  between its high-range and low-range positions. 
         [0063]    With particular reference now to  FIGS. 12 ,  15  and  16 A through  16 C, the secondary driveline  16 ′ can include the propshaft  86 , a two-speed rear drive module  100 ′, a pair of second axle shafts  102 L′ and  102 R′, and a set of second vehicle wheels  104 L and  104 R. A first end of the propshaft  86  is coupled to the output pinion shaft  60 ′ extending from the two-speed power take-off unit  18 ′ while a second end of the propshaft  86  is coupled for rotation with an input assembly  106 ′ of the two-speed rear drive module  100 ′. The rear drive module  100 ′ can include a housing  108 ′, a second differential  110 ′, a torque transfer device  112 ′, a TTD actuator  114 ′ for controlling actuation of the torque transfer device  112 ′, a two-speed range unit  278  having a planetary gear assembly  280  and a range shift mechanism  282 , and a range actuator  284 . 
         [0064]    The input assembly  106 ′ can include an input pinion shaft  116 ′ having a pinion gear  118 ′, a hollow spool  120 ′, and a hypoid gear  122 ′ fixed to a flange portion  156 ′ of the spool  120 ′ and which is meshed with the pinion gear  118 ′. The second differential  110 ′ is an epicyclic arrangement which can include an annulus gear  180 ′, sun gear  182 ′, a set of first planet gears  184 ′ meshed with the annulus gear  180 ′, a set of second planet gears  186 ′ meshed with the sun gear  182 ′, and a carrier unit  188  from which the first planet gears  184 ′ and the second planet gears  186 ′ are rotatably supported. The planet gears are circumferentially arranged such that each one of the first planet gears  184 ′ also meshes with at least one of the second planet gears  186 ′. The carrier unit  188 ′ can include a tubular boss  190 ′ that is configured to be connected via a splined connection  192 ′ to the second axle shaft  102 R′ while the sun gear  182 ′ can be connected via a splined connection  194 ′ to the second axle shaft  102 L′. 
         [0065]    Torque transfer device  112 ′ can include an input clutch member  130 ′ fixed for rotation with the hypoid gear  122 , an output clutch member  132 ′, and a multi-plate clutch pack  134 ′ operably disposed therebetween. A clutch drum  166 ′ can be integrated with the hypoid gear  122 ′ and act as the input clutch member  130 ′ while a clutch hub  168 ′ can act as the output clutch member  132 ′. The clutch pack  134 ′ is operably disposed between the clutch drum  166 ′ and the clutch hub  168 ′. The torque transfer device  112 ′ can also include an engagement mechanism  136 ′ that is moveable under the control of the TTD actuator  114 ′ based on control signals from the controller  150  to selectively apply a clutch engagement force to the clutch pack  134 ′. Thus, rotary power transferred from the input assembly  106 ′ through the torque transfer device  112 ′ is transmitted to the clutch hub  168 ′. The engagement mechanism  136 ′ can include an apply piston  170 ′ disposed for sliding movement in a pressure chamber  172 ′ which can be supplied with pressurized fluid by a hydraulically-operated unit associated with the TTD actuator  114 ′. The engagement mechanism  136 ′ can further include a plurality of circumferentially aligned load pins  266  each having a first end engaging the apply piston  170 ′ and a second end engaging an apply plate  268 . The apply plate  268  is configured to apply the clutch engagement force on the clutch pack  134 ′. 
         [0066]    The TTD actuator  114 ′ can be any power-operated device capable of shifting the torque transfer device  112 ′ between a first or “disconnected” mode and a second or “connected” mode. The first mode can be established when the engagement mechanism  136 ′ is positioned such that rotary power is not transmitted from the input clutch member  130 ′ to the output clutch member  132 ′. The second mode for the torque transfer device  112 ′ can be established when the clutch engagement force exerted by the engagement mechanism  136 ′ causes rotary power to be transmitted through the clutch pack  134 ′ to the output clutch member  132 ′. The TTD actuator  114 ′ can be generally similar to TTD actuator  114  and leadline  140 ′ is used to designate the mechanical or hydraulic connection between the TTD actuator  114 ′ and the engagement mechanism  136 ′. 
         [0067]    The two-speed range unit  278  is operable to establish at least two different speed ratio drive connections between the output clutch member  132 ′ of the torque transfer device  112 ′ and the second differential  110 ′. Specifically, the planetary gear assembly  280  can include a sun gear  290  fixed for rotation via a splined connection  292  with the clutch hub  168 ′, a ring gear  294 , a plurality of planet gears  296  meshed with the sun gear  290  and the ring gear  294 , and a planet carrier  298  from which the planet gears  296  are rotatably supported. The planet carrier  298  can be fixed for common rotation with the annulus gear  180 ′ of the second differential  110 ′. 
         [0068]    The range shift mechanism  282  can include a first or direct clutch ring  300  fixed for rotation with the clutch hub  168 ′, a second or low clutch ring  302  non-rotatably fixed to the housing  108 ′, a range collar  304 , and a range fork  306 . The load pins  266  are shown in  FIG. 16  to extend through a plurality of support bores formed through the second clutch ring  302 . The range collar  304  can include a set of internal spline teeth  308  that is in continuous meshed engagement with a set of external spline teeth  310  formed on the ring gear  294  of the planetary gear assembly  280 . As such, the range collar  304  is coupled for common rotation with the ring gear  294  while being capable of bi-directional axial sliding movement thereon. The range collar  304  can further include a set of first clutch teeth  312  that can be moved into and out of engagement with a set of clutch teeth  314  formed on the first clutch ring  300 , a set of second clutch teeth  316  that can be moved into and out of engagement with a set of clutch teeth  318  formed on the second clutch ring  302 , and a set of third clutch teeth  320  that can be moved into and out of engagement with a set of clutch teeth  322  formed on a third clutch ring  324  that is fixed for rotation with the annulus gear  180 ′. As will be detailed, translational movement of the range collar  304  is operable to establish at least two different speed range drive connections between the clutch hub  168 ′ of the torque transfer device  112 ′ and the annulus gear  180 ′ of the second differential  110 ′. 
         [0069]    The range collar  304  is shown in  FIG. 16A  positioned in a first or high range position such that its first clutch teeth  312  are meshed with the clutch teeth  314  on the first clutch ring  300  and its third clutch teeth  320  are meshed with the clutch teeth  322  on the annulus gear  180 ′. In addition, the second clutch teeth  316  on the range collar  304  are disengaged from engagement with the clutch teeth  318  on the second clutch ring  302 . With the range collar  304  located in its first range position, the range collar  304  directly couples the clutch hub  168 ′ to the annulus gear  180 ′. In addition, the sun gear  290  and the ring gear  294  are coupled together by the range collar  304  in its first range position such that the planetary gear assembly  280  is locked against relative rotation and rotates as a unit. Thus, the range collar  304  establishes a first or direct ratio drive connection between the output component (the output clutch member  132 ′) of the torque transfer device  112 ′ and the input component (the annulus gear  180 ′) of the second differential  110 ′ when located in its first range position. 
         [0070]    The range collar  304  is shown in  FIG. 16B  positioned in a second or neutral range position such that its first clutch teeth  312  are disengaged from the clutch teeth  314  on the first clutch ring  300 , its second clutch teeth  316  are disengaged from the clutch teeth  318  on the second clutch ring  302 , and its third clutch teeth  320  are disengaged from the clutch teeth  322  on the third clutch ring  324 . As such, the output clutch member  132 ′ of the torque transfer device  112 ′ is released from driven engagement with the annulus gear  180 ′ of the second differential  110 ′. 
         [0071]    The range collar  304  is shown in  FIG. 16C  positioned in a third or low range position such that its first clutch teeth  312  are disengaged from the clutch teeth  314  on the first clutch ring  300 , its second clutch teeth  316  are meshed with the clutch teeth  318  on the second clutch ring  302 , and its third clutch teeth  320  are disengaged from the clutch teeth  322  on the third clutch ring  324 . As such, the ring gear  294  is braked against rotation and driven rotation of the sun gear  290  (via the output clutch member  132 ′ of the torque transfer device  112 ′) causes the planet carrier  298  to drive the annulus gear  180 ′ at a reduced speed relative to the sun gear  290 , thereby establishing a second or reduced ratio drive connection between the output clutch member  132 ′ of the torque transfer device  112 ′ and the annulus gear  180 ′ of the second differential  110 ′. 
         [0072]    The range actuator  284  can be any type of power-operated mechanism that is operable to control axial translational movement of the range fork  306  which, in turn, causes movement of the range collar  304  between its three distinct range positions. The range actuator  284  is shown schematically to be mounted to the housing  108 ′ of the two-speed rear drive module  100 ′. The range actuator  284  can be a motor-driven geared device configured to receive control signals from the controller  150  and convert rotation of the motor output into translational movement of the range fork  306 . The range fork  306  is shown in  FIGS. 16A-16C  to extend through an opening in the housing  108 ′ and includes a projection  330  that extends into an annular grove  332  formed in the range collar  304 . 
         [0073]    In operation, the vehicle  10 ′ can normally be operated in a two-wheel high-range drive mode in which the power take-off unit  18 ′ establishes a high-range drive connection between the powertrain  12  and the primary driveline  16 ′ while the rear drive module  100 ′ is disengaged. Specifically, the range sleeve  224  and the mode collar  246  respectively associated with the range shift mechanism  202  and the disconnect mechanism  54 ′ are located as shown in  FIG. 14A  to establish the 2-Hi mode. With the mode collar  246  in its first mode position, the input shaft  204  is disconnected from the transfer shaft  64 ′ such that substantially all rotary power is transferred from the powertrain  12  to the primary driveline  16 ′. The torque transfer device  112 ′ is maintained in its first mode to disconnect the secondary driveline  20 ′. While the torque transfer device  112 ′ is operating in its first mode, the range collar  304  can be located in its high-range position ( FIG. 16A ). 
         [0074]    When it is desired or necessary to operate the motor vehicle  10 ′ in an all-wheel high-range (AWD-H) drive mode, the control system  22  can be activated to initially signal the TTD actuator  114 ′ to shift the torque transfer device  112 ′ into its second mode for synchronizing the speeds of the primary driveline  16 ′ and the secondary driveline  20 ′. Upon synchronization, the controller  150  signals the disconnect actuator  56 ′ to shift the mode collar  246  to its second mode position while maintaining the range sleeve  224  in its first range position ( FIG. 14B ). This establishes a four-wheel high-range drive connection between the powertrain  12 , the primary driveline  16 ′ and the input  106 ′ to the rear drive module  100 ′. In addition, the range actuator  284  can be actuated to maintain or move the range collar  304  into its high-range position ( FIG. 16A ) such that the rotary power delivered through the torque transfer device  112 ′ is transmitted to the second differential  110 ′ at the direct speed ratio. Thereafter, the TTD actuator  114 ′ can be controlled to vary the torque transmitted through the torque transfer device  112 ′ to the second vehicle wheels  104 L, 104 R. 
         [0075]    If during operation of the vehicle  10 ′ in its AWD-H drive mode, it is desired or determined that improved traction requires operation in an all-wheel drive low-range (AWD-L) drive mode, the control system  22  functions to coordinate shifting of the power take-off unit  18 ′ into its four-wheel low-range mode and the rear drive module  100 ′ into its low-range mode. Specifically, the positions of the mode collar  246  and the range sleeve  224  of the power take-off unit  18 ′ to establish this connection are shown in  FIG. 14D  while the position of the range collar  304  of the rear drive module  100 ′ to establish this connection is shown in  FIG. 16C . Thus, the low-range drive connections are established in the power take-off unit  18 ′ and the rear drive module  100 ′. These low-range drive connections can be established sequentially or concurrently based on a suitable control method and can be established with the vehicle  10 ′ in a stationary or non-motive state. 
         [0076]    Finally, a towing mode for the vehicle  10 ′ can be established by shifting the power take-off unit  18 ′ into its neutral mode ( FIG. 14C ) and the rear drive module  100 ′ into its neutral mode ( FIG. 16B ). 
         [0077]    Referring now to  FIG. 17 , a schematic view of an alternative exemplary embodiment of a two-speed rear drive module  100 ″ is shown which can be associated with the vehicle  10 ′ shown in  FIG. 10 . In essence, the two-speed rear drive module  100 ″ is generally similar to the two-speed rear drive module  100 ′ shown in  FIGS. 15 and 16  with the exception that a bevel-type second differential  110 ″ is substituted for the epicyclical second differential  110 ′. Thus, the two-speed range unit  278  is now operable to selectively establish drive connections between the output clutch member  132 ′ of the torque transfer device  112 ′ and the second differential case  124 ′ of the second differential  110 ″. Specifically, movement of the range collar  304  between its three range positions is operable to establish the direct ratio, neutral and reduced-ratio drive connections between the output component of the torque transfer device  112 ′ and the input component to the second differential  110 ″. 
         [0078]    The present disclosure relates generally to single-speed and two-speed disconnectable drivelines for use in all-wheel drive vehicles. To this end, it is desirable to provide power take-off units and rear drive modules that are configured to provide a compact arrangement for modular assembly. The single-speed rear drive modules  100  and  100 A of  FIGS. 8 and 9 , respectively, illustrates these desirable features in that the second differentials  110 ,  110 A are shown installed in a cantilevered manner relative to the bell-shaped spool  120  and the meshed hypoid gear  122  and pinion gear  118 . The concentric location of the torque transfer devices  112 ,  112 A relative to the second differentials  110 ,  110 A provides a compact axial arrangement. In addition, the bevel-type differential  110  can be substituted for the epicyclic differential  110 A with only minor changes made to the housing  108  to permit product modularity. The two-speed rear drive modules  100 ′ and  100 ″ also show these desirable features and provide for a compact arrangement of the two-speed reduction units between the torque transfer devices and the second differentials. 
         [0079]    While specific aspects have been described in the specification and illustrated in the drawings, it will be understood by those skilled in the art that various changes can be made and equivalents can be substituted for elements and components thereof without departing from the scope of the present teachings, as defined in the claims. Furthermore, the mixing and matching of features, elements, components and/or functions between various aspects of the present teachings are expressly contemplated herein so that one skilled in the art will appreciate from the present teachings that features, elements, components and/or functions of one aspect of the present teachings can be incorporated into another aspect, as appropriate, unless described otherwise above. Moreover, many modifications may be made to adapt a particular situation, configuration, or material to the present teachings without departing from the essential scope thereof. Therefore, it is intended that the present teachings not be limited to the particular aspects illustrated by the drawings and described in the specification as the best mode presently contemplated for carrying out the present teachings, but that the scope of the present teachings include many aspects and examples following within the foregoing description and the appended claims.