Patent Description:
Many vehicles today have an electric drive comprising an electric motor operatively coupled to an axle gearbox in lieu of and/or in addition to an internal combustion engine. An axle gearbox operatively coupled to an electric motor is generically described as an electric axle gearbox and/or an eAxle gearbox. The eAxle gearbox is typically operatively coupled to one or more wheels for propelling the vehicle.

One type of eAxle gearbox is a parallel axis gearbox. The parallel axis gearbox typically includes an input shaft, an intermediate shaft, a differential assembly, and a first and second output side shafts having respective axes of rotation that are parallel to one another. The input shaft is typically operatively coupled to an electric motor output shaft. In addition, the input shaft includes a first driving gear. Similarly, the intermediate shaft includes an intermediate driving gear. A first driven gear is fixedly coupled to the intermediate shaft and meshingly engaged with the driving gear on the input shaft. The first and second output side shafts are rotationally coupled through a differential assembly to an annular driven gear meshingly engaged with the intermediate driving gear.

Typically, the parallel axis gearbox includes a cover fixedly coupled to a housing to contain and support the internal components of the parallel axis gearbox. A plurality of mechanical fasteners are typically spaced around an outer perimeter of the cover to attach the cover to the housing. The cover has increased axial stiffness near the mechanical fasteners. However, the cover is typically less stiff in portions of the cover spaced apart from the mechanical fasteners. Since the cover and the housing contain and support the internal components of the gearbox, a reduction in stiffness of the cover in the axial direction of the intermediate shaft can result in increased deflections of the cover under load. Flexing of the cover under load can result in mesh misalignments between the meshed gears within the parallel axis gearbox. Further, each of the input shaft, the intermediate shaft, and the differential assembly are supported by bearings. The bearings can be misaligned due to deflections in the cover under load. Misalignments between meshed gears within the parallel axis gearbox increases the wear on the gears and reduce the durability of the gears. In addition, bearing misalignments increases bearing wear and further degrade the durability of the bearings.

Certain parallel axis gearboxes include an intermediate shaft having a longitudinal bore extending at least partially through the intermediate shaft. The intermediate shafts having a longitudinal bore are alternatively described as hollow intermediate shafts.

Typically, the intermediate shaft is positioned spaced apart from the outer perimeter of cover for the parallel axis gearbox. <CIT> generally discloses a first known parallel axis gearbox having an input shaft, an intermediate shaft, and a first and second output side shafts having respective axes of rotation that are parallel to one another. The input shaft is operatively coupled to an electric motor output shaft. In addition, the input shaft includes a first driving gear. Similarly, the intermediate shaft includes an intermediate driving gear. A longitudinal bore extends partially through the intermediate shaft. A first driven gear is fixedly coupled to the intermediate shaft and meshingly engaged with the first driving gear on the input shaft. The first and second output side shafts are rotationally coupled through a differential assembly to an annular driven gear meshingly engaged with the intermediate driving gear.

The internal components of the first known parallel axis gearbox are supported by and contained within a cover and a housing. A plurality of mechanical fasteners attach the cover to the housing around an outer perimeter of the cover. However, the cover lacks mechanical fasteners near the intermediate shaft. The cover has reduced axial stiffness under load near the intermediate shaft since the mechanical fasteners are spaced around the outer perimeter of the cover.

The <CIT> generally discloses a second known parallel axis gearbox also having an input shaft, an intermediate shaft, and a first and second output side shafts having respective axes of rotation that are parallel to one another. The input shaft is operatively coupled to an electric motor output shaft. In addition, the input shaft includes a first driving gear. Similarly, the intermediate shaft includes an intermediate driving gear. In addition, a longitudinal bore extends through the intermediate shaft. A first driven gear is fixedly coupled to the intermediate shaft and meshingly engaged with the first driving gear on the input shaft. The first and second output side shafts are rotationally coupled through a differential assembly to an annular driven gear meshingly engaged with the intermediate driving gear.

The housing of the second known parallel axis gearbox includes a first passageway opening for accessing the intermediate shaft and a second passageway opening for accessing the input shaft. Further, each of the first and second passageway openings are sealed by a respective first and second cover. An outer perimeter of each of the first and second covers are fastened to the housing by mechanical fasteners. The mechanical fasteners are spaced closer to the intermediate shaft in the second known parallel axis gearbox compared to the first known parallel axis gearbox. However, in the second known parallel axis gearbox, the first cover for the intermediate shaft can deflect under load. The first cover has reduced axial stiffness near the axis of rotation of the intermediate shaft since the mechanical fasteners are spaced around the outer perimeter of the first cover.

Therefore, it is desirable to reduce the potential for mesh misalignments within a parallel axis gearbox due to a cover over the intermediate shaft deflecting under load. Further, it is desirable to reduce the potential for bearing misalignments by reducing the potential for the cover to deflect under load. In addition, it is desirable to increase the stiffness of the cover in an axial direction of the intermediate shaft. Additionally, it is desirable to add a point of connection between the cover and the housing through the intermediate shaft. Finally, it is desirable to mechanically fasten the cover to the housing through a longitudinal bore passing through the intermediate shaft to increase the axial stiffness of the cover.

Reference is made to patent document <CIT>, which relates to a prior art electromotive drive assembly for a vehicle having a drive unit and a transmission arrangement within a housing arrangement including an intermediate plate between a first housing element and a second housing element.

The present invention relates to a parallel axis gearbox for a vehicle. The parallel axis gearbox includes an input shaft having a first axis of rotation and an intermediate shaft having a second axis of rotation parallel to the first axis of rotation. The intermediate shaft includes an intermediate driving gear, an intermediate driven gear, and a longitudinal bore passing through the intermediate shaft. The intermediate driven gear is meshingly engaged with a first driving gear on the input shaft. The input shaft and the intermediate shaft are contained within and supported by a cover fixedly coupled to a housing. A bolt fixedly couples the cover to the housing and passes through the longitudinal bore of the intermediate shaft. The invention is claimed in independent claims <NUM> and <NUM>.

<FIG>, <FIG>, and <FIG> illustrate a parallel axis gearbox <NUM> having a bolt <NUM> fastening a cover <NUM> to a housing <NUM> through an intermediate shaft <NUM>, according to embodiments described herein. Directional references employed or shown in the description, figures or claims, such as top, bottom, upper, lower, upward, downward, lengthwise, widthwise, left, right, and the like, are relative terms employed for ease of description and are not intended to limit the scope of the invention in any respect. Referring to the Figures, like numerals indicate like or corresponding parts throughout the several views.

<FIG> shows a partially transparent view of the parallel axis gearbox <NUM> having an intermediate shaft <NUM> supported and contained within the cover <NUM> and the housing <NUM>. An aligned cross-sectional view of the parallel axis gearbox <NUM> of <FIG> taken along section line A-A is shown in <FIG>. Referring to <FIG>, the parallel axis gearbox <NUM> includes an input shaft <NUM>, the intermediate shaft <NUM>, and first and second output side shafts <NUM>, <NUM>'. Each of the intermediate shaft <NUM>, the input shaft <NUM>, and the first and second output side shafts <NUM>, <NUM>' have axis of rotations 26A, 30A, 34A that are parallel to one another.

Referring to <FIG>, the input shaft <NUM> has a first shaft end <NUM> configured to operately couple with a motor output shaft of an electric drive motor. In addition, the input shaft <NUM> includes an integrally formed driving gear <NUM> spaced apart from a second shaft end <NUM>. In other embodiments, the driving gear <NUM> is a separate component that is fixedly coupled to the input shaft <NUM>. The first shaft end <NUM> of the input shaft <NUM> is supported and retained by a lower bearing <NUM> located within a lower bearing cavity <NUM> in the housing <NUM>. Similarly, the second shaft end <NUM> of the input shaft <NUM> is supported and retained by an upper bearing <NUM> located within an upper bearing cavity <NUM> formed in the cover <NUM>. The lower and upper bearings <NUM>, <NUM> supporting the input shaft <NUM> are shown as deep groove ball bearings, in <FIG>. However, alternate types of bearings and bearing mounting locations can be used without varying the scope of the invention. For example, both the lower and upper bearings <NUM>, <NUM> can be retained solely within the housing <NUM> if desired.

The intermediate shaft <NUM>, shown in <FIG>, includes a first shaft end <NUM>, a second shaft end <NUM>, an integrally formed intermediate driving gear <NUM> adjacent the first shaft end <NUM>, and an intermediate driven gear <NUM> fixedly coupled to the intermediate shaft <NUM> adjacent the second shaft end <NUM>. The intermediate driven gear <NUM> includes gear teeth <NUM> that are configured to meshingly engage with the driving gear <NUM> of the input shaft <NUM>. Further, the intermediate driven gear <NUM> revolves around the intermediate shaft <NUM> axis of rotation 26A. The first shaft end <NUM> of the intermediate shaft <NUM> is supported and retained by a lower intermediate bearing <NUM> located in a lower bearing cavity <NUM> formed in the housing <NUM>. Similarly, the second shaft end <NUM> of the intermediate shaft <NUM> is supported and retained by an upper intermediate bearing <NUM> located in an upper bearing cavity <NUM> formed in the cover <NUM>. In the embodiment shown in <FIG>, the lower and upper intermediate bearings <NUM>, <NUM> are tapered roller bearings, however, other types of bearings, such as deep groove ball bearings and the like, can be used without altering the scope of the invention. In addition, the lower and upper intermediate bearings <NUM>, <NUM> can be supported and retained within the housing <NUM> without altering the scope of the invention. Also shown in <FIG>, the intermediate shaft <NUM> includes a longitudinal bore <NUM> extending between the first shaft end <NUM> and the second shaft end <NUM> and aligned with the axis of rotation 26A of the intermediate shaft <NUM>. The intermediate shaft <NUM> having a longitudinal bore <NUM> is alternately described as a hollow intermediate shaft <NUM>.

An annular driven gear <NUM> is operatively coupled between the intermediate driving gear <NUM> and a differential assembly <NUM>, as illustrated in <FIG>. The annular driven gear <NUM> revolves around the axis of rotation 34A of the first and second output side shafts <NUM>, <NUM>'. Further, the annular driven gear <NUM> includes gear teeth <NUM> configured to matingly engage with the intermediate driving gear <NUM>. In the embodiment shown in <FIG>, the annular driven gear <NUM> is fixedly coupled to the first output side shaft <NUM> with the second output side shaft <NUM>' operately coupled to the first output side shaft <NUM> through the differential assembly <NUM>.

The differential assembly <NUM> shown in <FIG> includes at least a first side shaft gear <NUM> and a second side shaft gear <NUM> meshingly engaged with a pinion gear <NUM>. Each of the first and second side shaft gears <NUM>, <NUM> are fixedly coupled to the first and second output side shafts <NUM>, <NUM>', respectively. The first and second side shaft gears <NUM>, <NUM> and the pinion gear <NUM> are typically bevel gears. Each of the first and second output side shafts <NUM>, <NUM>' are supported by a first output bearing <NUM> and a second output bearing <NUM>, respectively. It is understood that the number, shape, size, and type of gears <NUM>, <NUM>, <NUM>, <NUM>, bearings <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, shafts <NUM>, <NUM>, <NUM>, <NUM>', and other components within the parallel axis gearbox <NUM>, as well as the components <NUM>, <NUM>, <NUM> of the differential assembly <NUM>, can vary without altering the scope of the invention. Further, it is understood that the parallel axis gearbox <NUM> can include more or less components without varying the scope of the invention.

In the embodiment shown in <FIG>, both the cover <NUM> and the housing <NUM> are formed of cast aluminum. However, it is understood that the cover <NUM> and the housing <NUM> can be formed from other materials and using alternate forming methods without altering the scope of the invention. Preferably, each the cover <NUM> and the housing <NUM> are formed out of metal. Further, it is understood that the size and shape of the cover <NUM> and the housing <NUM> can vary without altering the scope of the invention. Likewise, it is understood that the cover <NUM> can vary in size and shape, including comprising one or more separate covers fixedly coupled to different portions of the housing <NUM>.

As shown in <FIG> and <FIG>, the cover <NUM> is fixedly coupled to the housing <NUM> by a plurality of mechanical fasteners <NUM> spaced around an outer perimeter <NUM> of the cover <NUM>. Referring to <FIG>, each of the plurality of mechanical fasteners <NUM> includes a bolt shaft <NUM> projecting from a bolt head <NUM>. Each bolt shaft <NUM> is sized and shaped to pass into a respective passageway <NUM> in the cover <NUM>. The bolt shaft <NUM> of each mechanical fastener <NUM> extends through the respective passageway <NUM> in the cover <NUM> and into a respective cavity <NUM> in the housing <NUM>. Typically, each bolt head <NUM> is sized and shaped such that each bolt head <NUM> is larger than an inner diameter 146A of the respective passageway <NUM> in the cover <NUM>. Further, each bolt shaft <NUM> includes a threaded portion <NUM> configured to engage with the respective, correspondingly threaded, cavity <NUM> in the housing <NUM>.

<FIG> shows a cross-sectional view of the parallel axis gearbox <NUM> taken along section line B-B in <FIG>, illustration additional details of the bolt <NUM> fastening the cover <NUM> to the housing <NUM> and passing through the longitudinal bore <NUM> in the intermediate shaft <NUM>. Referring to <FIG>, the longitudinal bore <NUM> passing through the intermediate shaft <NUM> has a first inner diameter <NUM> extending between a first bore opening <NUM> adjacent the first shaft end <NUM> and a second bore opening <NUM> adjacent the second shaft end <NUM> of the intermediate shaft <NUM>. In addition, a longitudinal axis 102A of the longitudinal bore <NUM> is aligned with the axis of rotation 26A of the intermediate shaft <NUM>.

A housing boss <NUM> having a general cylindrically-shaped main portion 170A extends from the housing <NUM>, as shown in <FIG>. The housing boss <NUM> is sized and shaped such that a longitudinal axis 170B of the housing boss <NUM> is generally aligned with the axis of rotation 26A of the intermediate shaft <NUM> when the housing <NUM> is assembled with the intermediate shaft <NUM>. In the embodiment shown in <FIG>, the housing boss <NUM> is integrally formed with the housing <NUM> with both the housing <NUM> and the housing boss <NUM> being formed of cast aluminum. It is understood that the housing <NUM> and the housing boss <NUM> can be formed of different types of metals and manufactured using alternate manufacturing methods without varying the scope of the invention. Further, the housing boss <NUM> has an outer diameter <NUM> that is less than the inner diameter <NUM> of the longitudinal bore <NUM> passing through the intermediate shaft <NUM>. The housing boss <NUM> is sized and shaped to pass into the longitudinal bore <NUM> in the intermediate shaft <NUM> when the housing <NUM> is assembled with the intermediate shaft <NUM>. In addition, the housing boss <NUM> includes a housing boss end surface <NUM> that is generally perpendicular to the longitudinal axis 170B of the housing boss <NUM>.

A housing boss cavity <NUM> extends axially from an opening <NUM> in the housing boss <NUM> end surface <NUM> and terminates at a base surface <NUM> of the housing boss cavity <NUM>, as shown in <FIG>. Further, the housing boss cavity <NUM> has a minimum inner diameter 182A extending between the opening <NUM> and the base surface <NUM> of the housing boss cavity <NUM>. In addition, the housing boss cavity <NUM> has a longitudinal axis 182B that is aligned with the longitudinal axis 170B of the housing boss <NUM>.

A cover boss <NUM> having a general cylindrically-shaped main portion 186A extends from the cover <NUM>, as shown in <FIG>. The cover boss <NUM> is sized and shaped such that a longitudinal axis 186B of the cover boss <NUM> is generally aligned with the axis of rotation 26A of the intermediate shaft <NUM> when the cover <NUM> is assembled with the intermediate shaft <NUM>. In the embodiment shown in <FIG>, the cover boss <NUM> is integrally formed with the cover <NUM> with both the cover <NUM> and the cover boss <NUM> being formed of cast aluminum. It is understood that the cover <NUM> and the cover boss <NUM> can be formed of different types of metals and manufactured using alternate manufacturing methods without varying the scope of the invention. Further, the cover boss <NUM> has an outer diameter <NUM> that is less than the inner diameter <NUM> of the longitudinal bore <NUM> passing through the intermediate shaft <NUM>. The cover boss <NUM> is sized and shaped to pass into the longitudinal bore <NUM> in the intermediate shaft <NUM> when the cover <NUM> is assembled with the intermediate shaft <NUM>.

In addition, the cover boss <NUM> includes a cover boss end surface <NUM> that is generally perpendicular to the longitudinal axis 186B of the cover boss <NUM>, as shown in <FIG>. A cover boss bore <NUM> extends axially through the cover boss <NUM>. A longitudinal axis 198B of the cover boss bore <NUM> is generally aligned with the longitudinal axis 186B of the cover boss <NUM>. Further, the cover boss bore <NUM> has an inner diameter <NUM> extending between a first opening <NUM> on an exterior surface 18A of the cover <NUM> and a second opening <NUM> on the cover boss end surface <NUM>.

Referring to <FIG>, the cover boss <NUM> and the housing boss <NUM> are sized such that the cover boss <NUM> end surface <NUM> is generally parallel with the housing boss end surface <NUM> with the longitudinal axis 170B of the housing boss <NUM> generally aligned with the longitudinal axis 186B of the cover boss <NUM> when the cover <NUM> and the housing <NUM> are assembled as part of the parallel axis gearbox <NUM>. Further, after assembly, the cover boss bore <NUM> is generally aligned with the housing boss cavity <NUM>. In addition, the cover boss end surface <NUM> optionally frictionally engages with the housing boss end surface <NUM>.

Alternatively, as shown in <FIG>, the cover boss <NUM> and the housing boss <NUM> are sized and shaped such that the cover boss end surface <NUM> is spaced apart from the housing boss end surface <NUM> after the parallel axis gearbox <NUM> is assembled. In certain embodiments, a shim <NUM> is optionally placed between the cover boss end surface <NUM> and the housing boss end surface <NUM>. The shim <NUM> is generally disc-shaped having opposing upper and lower surfaces <NUM>, <NUM>, a passageway <NUM> extending between the opposing upper and lower surfaces <NUM>, <NUM>, and an outer edge surface <NUM> extending between the opposing upper and lower surfaces <NUM>, <NUM> defining a thickness of the shim <NUM>. The shim <NUM> is formed of a metal, a plastic, a rubber, and/or a combination thereof. Alternative embodiments of the shim <NUM> include a washer, a select fit shim, a spring washer, a select fit washer, a sleeve, a compressible seal, and the like, as well as combinations of one or more shims <NUM>. When the shim <NUM> is assembled with the cover boss <NUM> and the housing boss <NUM> as part of the parallel axis gearbox <NUM>, the passageway <NUM> has a longitudinal axis 218B that is generally aligned with the longitudinal axes 182B, 198B of the housing boss cavity <NUM> and the cover boss bore <NUM>. During assembly, fastening the bolt <NUM> connecting the cover <NUM> and the housing <NUM> compresses the shim <NUM>. Thus, in certain embodiments, the shim <NUM> is oversized to account for compression of the shim <NUM> during assembly when full bolt torque is applied to the bolt <NUM>. A combination of one or more shims <NUM> can be used to obtain the desired preload on the intermediate shaft <NUM> during the assembly process.

Also shown in <FIG>, the bolt <NUM> has a bolt shaft <NUM> extending from a bolt head <NUM> and defining a longitudinal axis 14A of the bolt <NUM>. The bolt shaft <NUM> is generally cylindrical-shaped and terminates at a bolt end surface <NUM>. In addition, the bolt shaft <NUM> and the passageway <NUM> through the shim <NUM> are sized and shaped such that the bolt shaft <NUM> can be inserted through the passageway <NUM> of the shim <NUM>. Further, an outer surface <NUM> of the bolt shaft <NUM> has a maximum outer diameter <NUM> generally less than or equal to the inner diameter <NUM> of the cover boss bore <NUM>. In the embodiment shown in <FIG>, the bolt shaft <NUM> includes a threaded portion <NUM> configured to matingly engage with a threaded portion <NUM> of the housing boss cavity <NUM>. A maximum outer diameter 238A of the threaded portion <NUM> of the bolt shaft <NUM> is equal to or greater than the minimum inner diameter 182A of the threaded portion <NUM> of the housing boss cavity <NUM>. Optionally, the threaded portion <NUM> of the bolt shaft <NUM> is configured to cut mating threads in the housing boss cavity <NUM> during assembly.

Referring to <FIG>, the bolt head <NUM> of the bolt <NUM> is sized and shaped such that the bolt head <NUM> frictionally engages the exterior surface 18A of the cover <NUM>. Further, the bolt head <NUM> has an outer perimeter <NUM> that is sized and shaped such that the bolt head <NUM> will not pass entirely through the cover boss bore <NUM>. In certain embodiments, the cover boss bore <NUM> includes an inlet cavity <NUM> adjacent the opening <NUM> in the cover <NUM> sized and shaped such that the bolt head <NUM> is at least partially recessed within the inlet cavity <NUM> when the bolt <NUM> is assembled as part of the parallel axis gearbox <NUM>. Optionally, one or more of a shim, a washer, and/or a compressible seal can be included between the bolt head <NUM> and the cover <NUM> during assembly.

As illustrated in <FIG>, when the bolt <NUM>, the cover <NUM>, the intermediate shaft <NUM>, and the housing <NUM> are assembled as part of the parallel axis gearbox <NUM>, the bolt <NUM> mechanically fastens the cover <NUM> to the housing <NUM> through the longitudinal bore <NUM> of the intermediate shaft <NUM>. In addition, the longitudinal axes 14A, 26A, 102A, 170B, 182B, 186B, 198B of the bolt <NUM>, the intermediate shaft <NUM>, the longitudinal bore <NUM> through the intermediate shaft <NUM>, the housing boss <NUM>, the housing boss cavity <NUM>, the cover boss <NUM>, and the cover boss bore <NUM> are generally aligned after assembly as part of the parallel axis gearbox <NUM>.

Referring to <FIG>, the bolt <NUM> passing through the longitudinal bore <NUM> of the intermediate shaft <NUM> fixedly couples the cover <NUM> to the housing <NUM>. The stiffness of a cover portion 18C near the intermediate shaft <NUM> in an axial direction 26B of the intermediate shaft <NUM> (illustrated by arrow 26B shown in <FIG>) is increased by adding a point of connection between the cover <NUM> and the housing <NUM> through the intermediate shaft <NUM>. The increased stiffness of the cover portion 18C near the intermediate shaft <NUM> reduces potential deflections of the cover <NUM> under load. Further, the potential for mesh misalignment between the intermediate driven gear <NUM> and the driving gear <NUM> of the input shaft <NUM> is reduced by the increased stiffness of the cover portion 18C. In addition, the potential for mesh misalignment between the intermediate driving gear <NUM> and the annular driven gear <NUM> is also reduced by the increase in stiffness of the cover portion 18C. Additionally, the potential for misalignment of the lower and upper intermediate bearings <NUM>, <NUM> is reduced in comparison to a known parallel axis gearbox 10P lacking a bolt <NUM> through the intermediate shaft <NUM>, such as shown in <FIG> and <FIG>.

Referring to <FIG>, the known parallel axis gearbox 10P includes a cover 18P fixedly coupled to a housing 22P by a plurality of mechanical fasteners 130P spaced around an outer perimeter 134P of the cover 18P. An aligned cross-sectional view of the known parallel axis gearbox 10P of <FIG> taken along section line C-C is shown in <FIG>. Referring to <FIG>, the known parallel axis gearbox 10P includes an input shaft 30P, an intermediate shaft 26P, and first and second output side shafts 34P, 34P'. Each of the intermediate shaft 26P, the input shaft 30P, and the first and second output side shafts 34P, 34P' have axes of rotations 26AP, 30AP, 34AP that are parallel to one another. The input shaft 30P has a first shaft end 38P configured to operately couple with a motor output shaft of an electric drive motor. In addition, the input shaft 30P includes an integrally formed driving gear 42P spaced apart from a second shaft end 46P.

The first shaft end 38P of the input shaft 30P, of the known parallel axis gearbox 10P shown in <FIG>, is supported and retained by a lower bearing 50P located within a lower bearing cavity 54P in the housing 22P. Similarly, the second shaft end 36P of the input shaft 30P is supported and retained by an upper bearing 58P located within an upper bearing cavity 62P formed in the cover 18P of the known parallel axis gearbox 10P.

The intermediate shaft 26P, of the known parallel axis gearbox shown in <FIG>, includes a first shaft end 66P, a second shaft end 70P, an integrally formed intermediate driving gear 74P adjacent the first shaft end 66P, and an intermediate driven gear 78P fixedly coupled to the intermediate shaft 26P adjacent the second shaft end 70P. The intermediate driven gear 78P includes gear teeth 82P that are configured to meshingly engage with the driving gear 42P of the input shaft 30P. Further, the intermediate driven gear 78P revolves around the intermediate shaft 26P axis of rotation 26AP. The first shaft end 66P of the intermediate shaft 26P is supported and retained by a lower intermediate bearing 86P located in a lower bearing cavity 90P formed in the cover 18P. Similarly, the second shaft end 70P of the intermediate shaft 26P is supported and retained by an upper intermediate bearing 94P located in an upper bearing cavity 98P formed in the cover <NUM>.

Also shown in <FIG>, the intermediate shaft 26P of the known parallel axis gearbox 10P includes a longitudinal bore 102P extending between the first shaft end 66P and the second shaft end 70P and aligned with the axis of rotation 26AP of the intermediate shaft 26P. The intermediate shaft 26P having a longitudinal bore 102P, such as shown in <FIG>, is alternately described as a hollow intermediate shaft 26P.

The known parallel axis gearbox 10P shown in <FIG> includes an annular driven gear 106P operatively coupled between the intermediate driving gear 74P and a differential assembly 108P. The annular driven gear 106P revolves around the axis of rotation 34AP of the first and second output side shafts 34P, 34P'. Further, the annular driven gear 106P includes gear teeth 110P configured to matingly engage with the intermediate driving gear 74P. The differential assembly 108P includes at least a first side shaft gear 114P and a second side shaft gear 116P meshingly engaged with a pinion gear 118P. Each of the first and second side shaft gears 114P, 116P are fixedly coupled to the first and second output side shafts 34P, 34P', respectively. Each of the first and second output side shafts 34P, 34P' are supported by a first output bearing 122P and a second output bearing 126P, respectively.

As shown in <FIG>, each of the plurality of mechanical fasteners 130P of the known parallel axis gearbox 10P includes a bolt shaft 138P projecting from a bolt head 142P. The bolt shaft 138P of each mechanical fastener 130P extends through a passageway 146P in the cover 18P and into a cavity 150P in the housing 22P. Typically, the bolt head 142P is sized and shaped such that the bolt head 142P is larger than the passageway 146P in the cover 18P. Further, the bolt shaft 138P includes a threaded portion 154P configured to mechanically engage with the cavity 150P in the housing 22P.

Referring to <FIG> and <FIG>, the cover 18P of the known parallel axis gearbox 10P is fastened to the housing 22P solely around the outer perimeter 134P of the cover 18P. In contrast, the embodiment of the parallel axis gearbox <NUM> shown in <FIG> includes the bolt <NUM> fixedly coupling the cover <NUM> to the housing through the intermediate shaft <NUM>. The only support between the cover 18P and the housing 22P of the known parallel axis gearbox 10P is along the outer perimeter 134P of the cover 18P, resulting in a cover portion 18P' near the intermediate shaft 26P being less stiff in an axial direction 26BP of the intermediate shaft 26P (illustrated by arrow 26BP in <FIG>) than portions 18P" of the cover 18P near the mechanical fasteners 130P. Thus, the cover portion 18P' of the cover 18P has an increased tendency to deflect under load. Deflections under load of the cover portion 18P' near the intermediate shaft <NUM> can increase potential mesh misalignments between the intermediate driven gear 78P and the driving gear 42P of the input shaft 30P, as well as between the intermediate driving gear 74P and the annular driven gear 106P. In addition, deflections of the cover 18P under load can result in increased bearing misalignment between the upper intermediate bearing 94P and the lower intermediate bearing 86P.

In contrast to the known parallel axis gearbox 10P, the embodiment of the parallel axis gearbox <NUM> shown in <FIG> includes a point of connection between the cover <NUM> and the housing <NUM>. Adding the bolt <NUM> passing through the longitudinal bore <NUM> of the intermediate shaft <NUM>, as shown in <FIG>, increases the stiffness of the cover portion 18C near the intermediate shaft <NUM> in an axial direction 26B of the intermediate shaft <NUM>. The increased stiffness in the axial direction 26B due to the inclusion of the point of connection between the cover <NUM> and the housing <NUM> through the intermediate shaft <NUM> improves gear durability and bearing durability by reducing gear mesh misalignments as well as reducing bearing misalignments. Further, the increased stiffness in the cover <NUM> near the intermediate shaft <NUM> reduces sensitivity of preload to thermal expansion since deflections of the cover <NUM> under load are reduced.

In the embodiment shown <FIG>, the cover <NUM> incudes a mounting surface 18B configured to matingly engage with a mounting surface 22B on the housing <NUM>. The end surface <NUM> of the cover boss <NUM> is spaced apart in the axial direction 26B from the mounting surface 18B of the cover <NUM> by a first predetermined distance <NUM>. Likewise, the end surface <NUM> of the housing boss <NUM> is spaced apart in the axial direction 26B from the mounting surface 22B of the housing <NUM> by a second predetermined distance <NUM>. The sum of the first and second predetermined distances <NUM>, <NUM> is selected to accommodate the shim <NUM> positioned between the end surfaces <NUM>, <NUM> of the cover boss <NUM> and the housing boss <NUM>. In certain embodiments, the sum of the first and second predetermined distances <NUM>, <NUM> is less than the uncompressed thickness of the shim <NUM> if the shim <NUM> will be compressed during assembly. In the embodiment shown in <FIG>, the axial distance between the upper and lower surfaces <NUM>, <NUM> of the shim <NUM> is less than the axial distance between the end surface <NUM> of the cover boss <NUM> and the opening <NUM> to the cover boss bore <NUM> adjacent the exterior surface 18A of the cover <NUM>. Further, the axial distance between the upper and lower surfaces <NUM>, <NUM> of the shim <NUM> is less than the axial distance between the end surface <NUM> of the housing boss <NUM> and an exterior surface 22A of the housing <NUM> adj acent the intermediate shaft <NUM>. It is understood that the relative axial distances between the upper and lower surfaces <NUM>, <NUM> of the shim <NUM>, between the end surface <NUM> of the cover boss <NUM> and the opening <NUM> to the cover boss bore <NUM>, and between the end surface <NUM> of the housing boss <NUM> and the exterior surface 22A of the housing <NUM> can vary without altering the scope of the invention.

<FIG> illustrates a second embodiment of a parallel axis gearbox <NUM>' having a cover <NUM>' with a modified cover boss <NUM>', having housing <NUM>' with a modified housing boss <NUM>', and having a spacer <NUM>' positioned between the modified cover boss <NUM>' and the modified housing boss <NUM>'. As with the first embodiment, the second embodiment includes an intermediate shaft <NUM> having a longitudinal bore <NUM> extending between a first intermediate shaft end <NUM> and a second intermediate shaft end <NUM> aligned with the axis of rotation 26A of the intermediate shaft <NUM>. In addition, the longitudinal bore <NUM> has a first inner diameter <NUM> extending between a first bore opening <NUM> adjacent the first shaft end <NUM> and a second bore opening <NUM> adjacent the second shaft end <NUM> of the intermediate shaft <NUM>.

Also shown in <FIG>, each of the first and second intermediate shaft ends <NUM>, <NUM> are supported and retained by respective lower and upper bearings <NUM>, <NUM>. The lower bearing <NUM> is retained within a cavity <NUM> in the housing <NUM>'. Further, the upper bearing <NUM> is retained within a cavity <NUM> in the cover <NUM>'. In addition, an intermediate driven gear <NUM> is fixedly coupled to the intermediate shaft <NUM>. An intermediate driving gear <NUM> is integrally formed with the intermediate shaft <NUM>.

The modified housing boss <NUM>' having a general cylindrical-shaped main portion 170A' extends from the housing <NUM>', as shown in <FIG>. The modified housing boss <NUM>' is sized and shaped such that a longitudinal axis 170B of the modified housing boss <NUM>' is aligned with the axis of rotation 26A of the intermediate shaft <NUM> when the housing <NUM>' is assembled with the intermediate shaft <NUM>. In the second embodiment shown in <FIG>, the modified housing boss <NUM>' is integrally formed with the housing <NUM>' with both the housing <NUM>' and the modified housing boss <NUM>' being formed of cast aluminum. It is understood that the housing <NUM>' and the modified housing boss <NUM>' can be formed of different types of metals and manufactured using alternate manufacturing methods without varying the scope of the invention. Further, the modified housing boss <NUM>' has an outer diameter <NUM>' that is less than an inner diameter <NUM> of the longitudinal bore <NUM> passing through the intermediate shaft <NUM>. The modified housing boss <NUM>' is sized and shaped to such that the modified housing boss <NUM>' can pass into the longitudinal bore <NUM> in the intermediate shaft <NUM> when the housing <NUM>' is assembled with the intermediate shaft <NUM>. In addition, the modified housing boss <NUM>' includes a housing boss end surface <NUM>' that is generally perpendicular to the longitudinal axis 170B of the modified housing boss <NUM>'.

The second embodiment includes a housing boss cavity <NUM>' extending axially from an opening <NUM>' in the housing boss end surface <NUM>' and terminates at a base surface <NUM>' of the housing boss cavity <NUM>', as shown in <FIG>. Further, the housing boss cavity <NUM>' is sized and shaped to matingly engage with a threaded portion <NUM>' of a bolt <NUM>' passing through the intermediate shaft <NUM>. In addition, the housing boss cavity <NUM>' has a longitudinal axis 182B that is generally aligned with the longitudinal axis 170B of the modified housing boss <NUM>'.

The modified cover boss <NUM>', of the second embodiment shown in <FIG>, has a general cylindrical-shaped main portion 186A' extending from the cover <NUM>'. The modified cover boss <NUM>' is sized and shaped such that a longitudinal axis 186B of the modified cover boss <NUM>' is generally aligned with the axis of rotation 26A of the intermediate shaft <NUM> when the cover <NUM>' is assembled with the intermediate shaft <NUM>. In the embodiment shown in <FIG>, the modified cover boss <NUM>' is integrally formed with the cover <NUM>' with both the cover <NUM>' and the modified cover boss <NUM>' being formed of cast aluminum. It is understood that the cover <NUM>' and the modified cover boss <NUM>' can be formed of different types of metals and manufactured using alternate manufacturing methods without varying the scope of the invention. Further, the modified cover boss <NUM>' has an outer diameter <NUM>' that is less than the inner diameter <NUM> of the longitudinal bore <NUM> passing through the intermediate shaft <NUM>. The modified cover boss <NUM>' is sized and shaped to such that the modified cover boss <NUM>' can pass into the longitudinal bore <NUM> in the intermediate shaft <NUM> when the cover <NUM>' is assembled with the intermediate shaft <NUM>.

In addition, the modified cover boss <NUM>' includes a cover boss end surface <NUM>' that is generally perpendicular to the longitudinal axis 186B of the modified cover boss <NUM>', as shown in <FIG>. A cover boss bore <NUM>' extends axially through the modified cover boss <NUM>' between a first opening <NUM>' on an exterior surface 18A' of the cover <NUM>' and a second opening <NUM>' on the cover boss end surface 194A'. The longitudinal axis 198B of the cover boss bore <NUM>' is generally aligned with the longitudinal axis 186B of the modified cover boss <NUM>'.

Referring to <FIG>, the modified cover boss <NUM>' and the modified housing boss <NUM>' are sized such that the cover boss end surface <NUM>' is generally parallel with and spaced apart from the housing boss end surface <NUM>' with the longitudinal axis 170B of the modified housing boss <NUM>' aligned with the longitudinal axis 186B of the modified cover boss <NUM>' when the cover <NUM>' and the housing <NUM>' are assembled as part of the parallel axis gearbox <NUM>'. Further, after assembly, the cover boss bore <NUM>' is generally aligned with the housing boss cavity <NUM>'.

The spacer <NUM>' is assembled between the modified cover boss end surface <NUM>' and the modified housing boss end surface <NUM>', as shown in <FIG>. In the embodiment shown in <FIG>, the spacer <NUM>' is generally a cylindrically-shaped sleeve having opposing upper and lower surfaces <NUM>', <NUM>', a passageway <NUM>' extending longitudinally between the opposing upper and lower surfaces <NUM>', <NUM>', and an outer edge surface <NUM>' extending between the opposing upper and lower surfaces <NUM>', <NUM>' defining a length of the spacer <NUM>'. The spacer <NUM>' is preferably formed of a metal such as steel, aluminum, and the like as non-limiting examples. Optionally, one or more shims <NUM>, such as shown in <FIG>, can be assembled with the spacer <NUM>'. When the spacer <NUM>' is assembled with the modified cover boss <NUM>' and the modified housing boss <NUM>' as part of the parallel axis gearbox <NUM>', the passageway <NUM>' of the spacer <NUM>' has a longitudinal axis 218B that is generally aligned with the longitudinal axes 182B, 198B of the housing boss cavity <NUM>' and the cover boss bore <NUM>'. During assembly, fastening the bolt <NUM>' connecting the cover <NUM>' and the housing <NUM>' compresses the spacer <NUM>'. Thus, in certain embodiments, the spacer <NUM>' is oversized to account for compression of the spacer <NUM>' during assembly when full bolt torque is applied to the bolt <NUM>'. A combination of one or more shims <NUM> in addition to the spacer <NUM>' can be used to obtain the desired preload on the intermediate shaft <NUM> during the assembly process.

Also shown in <FIG>, the bolt <NUM>' has a bolt shaft <NUM>' extending from a bolt head <NUM>' and defining a longitudinal axis 14A of the bolt <NUM>'. The bolt shaft <NUM>' is generally cylindrical-shaped and terminates at a bolt end surface <NUM>'. Further, an outer surface <NUM>' of the bolt shaft <NUM>' has a maximum outer diameter <NUM>' generally less than or equal to the inner diameter <NUM>' of the cover boss bore <NUM>'. In addition, the spacer <NUM>' has a minimum inner diameter 218C that is generally larger than the maximum outer diameter <NUM>' of the bolt shaft <NUM>'. Furthermore, the threaded portion <NUM>' of the bolt shaft <NUM>' is configured to matingly engage with a threaded portion <NUM>' of the housing boss cavity <NUM>'. Optionally, the threaded portion <NUM>' of the bolt shaft <NUM>' is configured to cut mating threads in the housing boss cavity <NUM>' during assembly.

In the second embodiment shown in <FIG>, the bolt head <NUM>' of the bolt <NUM>' is sized and shaped such that the bolt head <NUM>' frictionally engages the exterior surface 18A' of the cover <NUM>'. Further, the bolt head <NUM>' has an outer perimeter <NUM>' that is sized and shaped such that the bolt head <NUM>' will not pass entirely through the cover boss bore <NUM>'. In certain embodiments, the cover boss bore <NUM>' includes an inlet cavity <NUM>' adjacent the opening <NUM>' in the cover <NUM>' sized and shaped such that the bolt head <NUM>' is at least partially recessed within the inlet cavity <NUM>' when the bolt <NUM>' is assembled as part of the parallel axis gearbox <NUM>'. Optionally, one or more of a shim, a washer, and/or a compressible seal can be included between the bolt head <NUM>' and the cover <NUM>' during assembly.

As illustrated in <FIG>, when the bolt <NUM>', the cover <NUM>', the intermediate shaft <NUM>, the spacer <NUM>', and the housing <NUM>' are assembled as part of the parallel axis gearbox <NUM>', the bolt <NUM>' mechanically fastens the cover <NUM>' to the housing <NUM>' through the longitudinal bore <NUM> of the intermediate shaft <NUM>. In addition, the longitudinal axes 14A, 26A, 102A, 170B, 182B, 186B, 198B of the bolt <NUM>', the intermediate shaft <NUM>', the longitudinal bore <NUM> through the intermediate shaft <NUM>, the housing boss <NUM>', the housing boss cavity <NUM>', the cover boss <NUM>', the cover boss bore <NUM>', and the spacer <NUM>' are generally aligned after assembly as part of the parallel axis gearbox <NUM>'.

In the second embodiment shown <FIG>, the cover <NUM>' has a mounting surface 18B' configured to matingly engage with a mounting surface 22B' of the housing <NUM>'. The intermediate shaft <NUM> defines an axial direction 26B of the parallel axis gearbox <NUM>', as illustrated by arrow 26B in <FIG>. The end surface <NUM>' of the modified cover boss <NUM>' is spaced apart in the axial direction 26B from the mounting surface 18B' of the cover <NUM>' by a first predetermined distance <NUM>'. Likewise, the end surface <NUM>' of the housing boss <NUM>' is spaced apart in the axial direction 26B from the mounting surface 22B' of the housing <NUM>' by a second predetermined distance <NUM>'. The sum of the first and second predetermined distances <NUM>', <NUM>' is selected to accommodate the spacer <NUM>' positioned between the end surfaces <NUM>', <NUM>' of the modified cover boss <NUM>' and the modified housing boss <NUM>'. In certain embodiments, the sum of the first and second predetermined distances <NUM>', <NUM>' is less than the uncompressed distance between the upper and lower surfaces <NUM>', <NUM>' of the spacer <NUM>' if the spacer <NUM>' is compressed during assembly. In other embodiments, the overall length of the spacer <NUM>' is selected based in part on the sum of the first and second predetermined distances <NUM>', <NUM>'. In addition, one or more of a supplemental shim, a washer, a compressible shim, a spring washer, and the like, as non-limiting examples, can be selectively assembled with the spacer <NUM>' to compensate for component dimensional variation.

The axial distance between the upper and lower surfaces <NUM>', <NUM>' of the spacer <NUM>' shown in <FIG> is greater than the axial distance between the end surface <NUM>' of the modified cover boss <NUM>' and the opening <NUM>' of the cover boss bore <NUM>' adjacent the exterior surface 18A' of the cover <NUM>'. Further, the axial distance between the upper and lower surfaces <NUM>', <NUM>' of the spacer <NUM>' is greater than the axial distance between the end surface <NUM>' of the housing boss <NUM>' and the exterior surface 22A' of the housing <NUM>'. It is understood that the relative axial distances between the upper and lower surfaces <NUM>', <NUM>' of the spacer <NUM>', between the end surface <NUM>' of the modified cover boss <NUM>' and the opening <NUM>' to the cover boss bore <NUM>', and between the end surface <NUM>' of the modified housing boss <NUM>' and the exterior surface 22A' of the housing <NUM>' can vary without altering the scope of the invention. Further, it is understood that the relative sizes, shapes, and overall lengths of the modified cover boss <NUM>', the modified housing boss <NUM>', and the spacer <NUM>' can vary without altering the scope of the invention.

Referring to <FIG>, the bolt <NUM>' passing through the longitudinal bore <NUM> of the intermediate shaft <NUM> fixedly couples the cover <NUM>' to the housing <NUM>'. The stiffness of a cover portion 18C' near the intermediate shaft <NUM> in the axial direction 26B, illustrated by arrow 26B shown in <FIG>, is increased by adding a point of connection between the cover <NUM>' and the housing <NUM>' through the intermediate shaft <NUM>. The increased stiffness of the cover portion 18C' near the intermediate shaft <NUM> reduces potential deflections of the cover <NUM>' under load. Further, the potential for mesh misalignment between the intermediate driven gear <NUM> and the driving gear <NUM> is reduced by the increased stiffness of the cover portion 18C'. In addition, the potential for mesh misalignment between the intermediate driving gear <NUM> and the annular driven gear <NUM> is also reduced by the increase of stiffness of the cover portion 18C'. Additionally, the potential for misalignment of the lower and upper intermediate bearings <NUM>, <NUM> is reduced in compared to the known parallel axis gearbox 10P lacking a bolt <NUM>' through the intermediate shaft <NUM>.

A third embodiment of a parallel axis gearbox <NUM>" according to claim <NUM> is shown in <FIG>. Both the second and third embodiments of the parallel axis gearbox <NUM>', <NUM>", shown in <FIG> and <FIG>, respectively, include an intermediate shaft subassembly <NUM> comprising at least an intermediate shaft <NUM> with a longitudinal bore <NUM>, lower and upper bearings <NUM>, <NUM>, and the intermediate driven gear <NUM>. Further, both the second and third embodiments of the parallel axis gearbox <NUM>', <NUM>" include a modified housing boss <NUM>' projecting from a housing <NUM>', and a bolt <NUM>" and a spacer <NUM>" inserted into the intermediate shaft <NUM> longitudinal bore <NUM>. In addition, the third embodiment includes a cover <NUM>" having a cover mounting surface 18B" configured to be fixedly coupled to a housing mounting surface 22B' of the housing <NUM>'.

However, the third embodiment shown in <FIG> includes a cap <NUM> inserted into a passageway <NUM> in the cover <NUM>" providing access to a cover bearing cup <NUM> that supports and retains the upper intermediate bearing <NUM>. When assembled, the cap <NUM> seats against the cover bearing cup <NUM>. The cap <NUM> is configured to matingly engage with the passageway <NUM> in the cover <NUM>". A channel <NUM> extends circumferentially around the cap <NUM> and is configured to support and retain a compressible seal <NUM>. The compressible seal <NUM> abuts the passageway <NUM> in the cover <NUM>" when the cap <NUM> is inserted into the passageway <NUM> , forming a tight seal between the cap <NUM> and the cover <NUM>".

In addition, the cap <NUM> shown in <FIG> includes a cap boss <NUM>" having a general cylindrical-shaped main portion 186A" extending from the cap <NUM>. The cap boss <NUM>" is sized and shaped such that a longitudinal axis 186B of the cap boss <NUM>" is aligned with the axis of rotation 26A of the intermediate shaft <NUM> when the cap <NUM> and the cover <NUM>" are assembled with the intermediate shaft <NUM>. In the embodiment shown in <FIG>, the cap boss <NUM>" is integrally formed with the cap <NUM> and is formed of a metal such as cast aluminum, steel, and the like. It is understood that the cap <NUM> and cover <NUM>" can be formed of different types of metals and manufactured using alternate manufacturing methods without varying the scope of the invention. The cap boss <NUM>" includes an end surface <NUM>" that is generally perpendicular to the longitudinal axis 186B of the cap boss <NUM>", as shown in <FIG>. Further, the cap boss <NUM>" is sized and shaped such that the end surface <NUM>" of the cap boss <NUM>" will pass into the second bore opening <NUM> of the longitudinal bore <NUM> when the cap <NUM> and the cover <NUM>" are assembled with the intermediate shaft <NUM>.

Referring to <FIG>, a cap boss bore <NUM>" extends axially through the cap boss <NUM>" between a first opening <NUM>" on an exterior surface 270A of the cap <NUM> and a second opening <NUM>" on the cap boss end surface <NUM>". A longitudinal axis 198B of the cap boss bore <NUM>" is generally aligned with the longitudinal axis 186B of the cap boss <NUM>".

As shown in <FIG>, the cap boss <NUM>" and the modified housing boss <NUM>' are sized and shaped such that the cap boss end surface <NUM>" is generally parallel with and spaced apart from the modified housing boss end surface <NUM>' with the longitudinal axis 170B of the modified housing boss <NUM>' generally aligned with the longitudinal axis 186B of the cap boss <NUM>" when the cap <NUM>, the cover <NUM>", and the housing <NUM>' are assembled as part of the parallel axis gearbox <NUM>". Further, after assembly, the cap boss bore <NUM>" is generally aligned with the housing boss cavity <NUM>'.

The spacer <NUM>" is assembled between the cap boss end surface <NUM>" and the modified housing boss end surface <NUM>', as shown in <FIG>. In the embodiment shown in <FIG>, the spacer <NUM>" is generally a cylindrically-shaped sleeve having opposing upper and lower surfaces <NUM>", <NUM>", a passageway <NUM>" extending longitudinally between the opposing upper and lower surfaces <NUM>", <NUM>", and an outer edge surface <NUM>" extending between the opposing upper and lower surfaces <NUM>", <NUM>" defining a length of the spacer <NUM>". The spacer <NUM>" is preferably formed of a metal such as steel, aluminum, and the like as non-limiting examples. Optionally, one or more shims <NUM>, such as shown in <FIG>, can be assembled with the spacer <NUM>". When the spacer <NUM>" is assembled with the cap boss <NUM>" and the modified housing boss <NUM>' as part of the parallel axis gearbox <NUM>", the passageway <NUM>" of the spacer <NUM>" has a longitudinal axis 218B that is generally aligned with the longitudinal axes 182B, 198B of the housing boss cavity <NUM>' and the cap boss bore <NUM>". During assembly, fastening the bolt <NUM>" between the cap <NUM> and the housing <NUM>' compresses the spacer <NUM>". Thus, in certain embodiments, the spacer <NUM>" is oversized to account for compression of the spacer <NUM>" during assembly when full bolt torque is applied to the bolt <NUM>". A combination of one or more shims <NUM> in addition to the spacer <NUM>" can be used to obtain the desired preload on the intermediate shaft <NUM> during the assembly process.

Also shown in <FIG>, the bolt <NUM>" has a bolt shaft <NUM>" extending from a bolt head <NUM>" defining a longitudinal axis 14A of the bolt <NUM>". The bolt shaft <NUM>" is generally cylindrical-shaped and terminates at a bolt end surface <NUM>". Further, an outer surface <NUM>" of the bolt shaft <NUM>" is sized and shaped such that the bolt shaft <NUM>" can pass through the cap boss bore <NUM>" and through the spacer <NUM>" passageway <NUM>". Furthermore, the bolt shaft <NUM>" includes a threaded portion <NUM>" configured to matingly engage with a threaded portion <NUM>' of the housing boss cavity <NUM>'. Optionally, the threaded portion <NUM>" of the bolt shaft <NUM>" is configured to cut mating threads in the housing boss cavity <NUM>' during assembly.

In the third embodiment shown in <FIG>, the bolt head <NUM>" of the bolt <NUM>" is sized and shaped such that the bolt head <NUM>" frictionally engages the exterior surface 270A of the cap <NUM>. Further, the bolt head <NUM>" has an outer perimeter <NUM>" that is sized and shaped such that the bolt head <NUM>" will not pass entirely through the cap boss bore <NUM>". In certain embodiments, the cap boss bore <NUM>" includes an inlet cavity <NUM>" adjacent the opening <NUM>" in the cap <NUM> sized and shaped such that the bolt head <NUM>" is at least partially recessed within the inlet cavity <NUM>" when the bolt <NUM>" is assembled as part of the parallel axis gearbox <NUM>". Optionally, one or more of a shim, a washer, and/or a compressible seal can be included between the bolt head <NUM>" and the cap <NUM> during assembly.

As illustrated in <FIG>, when the bolt <NUM>", the cover <NUM>", the cap <NUM>, the intermediate shaft <NUM>, the spacer <NUM>", and the housing <NUM>' are assembled as part of the parallel axis gearbox <NUM>", the bolt <NUM>" mechanically fastens the cap <NUM> to the housing <NUM>' through the longitudinal bore <NUM> of the intermediate shaft <NUM>. In addition, the longitudinal axes 14A, 26A, 102A, 170B, 182B, 186B, 198B of the bolt <NUM>", the intermediate shaft <NUM>, the longitudinal bore <NUM> through the intermediate shaft <NUM>, the modified housing boss <NUM>', the housing boss cavity <NUM>', the cap boss <NUM>", the cap boss bore <NUM>", and the spacer <NUM>" are generally aligned after assembly as part of the parallel axis gearbox <NUM>".

In the third embodiment shown <FIG>, the end surface <NUM>" of the cap boss <NUM>" is spaced apart in the axial direction 26B from the mounting surface 18B" of the cover <NUM>" by a first predetermined distance <NUM>" after the cap <NUM> is assembled with the cover <NUM>". Likewise, the end surface <NUM>' of the housing boss <NUM>' is spaced apart in the axial direction 26B from the mounting surface 22B' of the housing <NUM>' by a second predetermined distance <NUM>'. The sum of the first and second predetermined distances <NUM>", <NUM>" is selected to accommodate the spacer <NUM>" positioned between the end surfaces <NUM>", <NUM>" of the cap boss <NUM>" and the modified housing boss <NUM>'. In certain embodiments, the sum of the first and second predetermined distances <NUM>", <NUM>" is less than the uncompressed distance between the upper and lower surfaces <NUM>", <NUM>" of the spacer <NUM>" if the spacer <NUM>" is compressed during assembly. In other embodiments, the overall length of the spacer <NUM>" is selected based in part on the sum of the first and second predetermined distances <NUM>", <NUM>". In addition, one or more of a supplemental shim, a washer, a compressible shim, a spring washer, and the like, as non-limiting examples, can be selectively assembled with the spacer <NUM>" to compensate for component dimensional variation.

The axial distance between the upper and lower surfaces <NUM>", <NUM>" of the spacer <NUM>" in the third embodiment shown in <FIG> is greater than the axial distance between the end surface <NUM>" of the cap boss <NUM>" and the opening <NUM>" to the cap boss bore <NUM>" adjacent the exterior surface 270A' of the cap <NUM>. Further, the axial distance between the upper and lower surfaces <NUM>", <NUM>" of the spacer <NUM>" is greater than the axial distance between the end surface <NUM>' of the housing boss <NUM>' and the exterior surface 22A' of the housing <NUM>'. It is understood that the relative axial distances between the upper and lower surfaces <NUM>", <NUM>" of the spacer <NUM>", between the end surface <NUM>" of the cap boss <NUM>" and the opening <NUM>" to the cap boss bore <NUM>", and between the end surface <NUM>' of the modified housing boss <NUM>' and the exterior surface 22A' of the housing <NUM>' can vary without altering the scope of the invention. Further, it is understood that the relative sizes, shapes, and overall lengths of the cap boss <NUM>", the modified housing boss <NUM>', and the spacer <NUM>" can vary without altering the scope of the invention. In addition, it is understood that the overall lengths of the cap boss <NUM>" and the modified housing boss <NUM>' can be increased and the spacer <NUM>" replaced by a shim <NUM>, such as shown in the first embodiment of <FIG>.

Referring to <FIG>, the bolt <NUM>" passing through the longitudinal bore <NUM> of the intermediate shaft <NUM> fixedly couples the cap <NUM> to the housing <NUM>'. The axial stiffness is increased of a cap portion 270B near the intermediate shaft <NUM> by adding a point of connection between the cap <NUM> and the housing <NUM>' through the intermediate shaft <NUM>. The increased stiffness of the cap portion 270B near the intermediate shaft <NUM> reduces potential deflections of the cap <NUM> under load. Since the cover bearing cup <NUM> is effectively axially freed from the cover <NUM>", the bolt <NUM>" doesn't offer additional stiffness to the cover <NUM>". However, the bolt <NUM>" does offer additional stiffness to the intermediate shaft subassembly <NUM>.

One benefit of the bolt <NUM>, <NUM>', <NUM>" though the intermediate shaft <NUM> of the parallel axis gearbox <NUM>, <NUM>', <NUM>" is an added point of connection between the housing <NUM>, <NUM>' and the cover <NUM>, <NUM>' / cap <NUM> through the intermediate shaft <NUM>. A second benefit is axial stiffness of the cover <NUM>, <NUM>'/ cap <NUM> is increased since the bolt <NUM>, <NUM>', <NUM>" passes through the intermediate shaft <NUM> and is fixedly coupled to the housing <NUM>, <NUM>'. A third benefit is the bolt <NUM>, <NUM>', <NUM>" passing through the intermediate shaft adds stiffness to the intermediate shaft assembly <NUM>. A fourth benefit is the increased stiffness of the intermediate shaft assembly <NUM> and/or increased stiffness in the cover <NUM>, <NUM>' reduces the potential for mesh misalignments within the parallel axis gearbox <NUM>, <NUM>', <NUM>". A fifth benefit is a reduced potential for bearing misalignments since the potential for the cover <NUM>, <NUM>' deflecting under load is reduced by the bolt <NUM>, <NUM>', <NUM>" connecting the cover <NUM>, <NUM>' to the housing <NUM>, <NUM>' through the intermediate shaft <NUM>.

Claim 1:
A parallel axis gearbox (<NUM>) for a vehicle, comprising:
a housing (<NUM>);
a cover (<NUM>) fixedly coupled to said housing (<NUM>);
an input shaft (<NUM>) having a first driving gear (<NUM>) and having a first axis of rotation (30A), said input shaft (<NUM>) rotatably supported between said housing (<NUM>) and said cover (<NUM>);
an intermediate shaft (<NUM>) having an intermediate driving gear (<NUM>), an intermediate driven gear (<NUM>), and a longitudinal bore (<NUM>) extending through said intermediate shaft (<NUM>), said intermediate driven gear (<NUM>) meshingly engaged with said first driving gear (<NUM>) of said input shaft (<NUM>) and having a second axis of rotation (26A), said second axis of rotation (26A) being parallel to said first axis of rotation (30A), said intermediate shaft (<NUM>) rotatably supported between said housing (<NUM>) and said cover (<NUM>); and
a bolt (<NUM>) fixedly coupling said cover (<NUM>) to said housing (<NUM>);
characterized in that:
a cover boss (<NUM>) projects from said cover (<NUM>) and terminates at a cover boss end surface (<NUM>);
a cover boss bore (<NUM>) extends longitudinally through said cover boss (<NUM>) between a first opening (<NUM>) on an exterior surface (18A) of said cover (<NUM>) and a second opening in said cover boss end surface (<NUM>); and
said bolt (<NUM>) passing through said cover boss bore (<NUM>) and said longitudinal bore (<NUM>) of said intermediate shaft (<NUM>).