Background of the Invention Typically, work machines, such as mining trucks are equipped with a traction assembly or device. These traction devices operate to automatically increase the traction of the work machine by decreasing the rotation of a wheel that is slipping on a relatively slick surface (e. g. a gravel surface). The slipping is detected by sensor assemblies included in the traction device that measure the rotation rate of each wheel axle.

Specifically, when the traction device detects (via one of the sensor assemblies) that a wheel axle is rotating at an unusually high rate as compared to the rotation rates of the other wheel axles, the traction device sends a signal to a mechanism that decreases the rotation rate of that wheel axle thereby decreasing the rotation rate of the slipping wheel.

Decreasing the rotation rate of the slipping wheel increases the traction of the work machine.

In order to measure the rotation rate of the wheel axle in the above described manner, some traction devices locate the sensor assembly in the spindle of the wheel group of the work machine.

However, locating the sensor assembly in the spindle

makes the sensor assembly difficult to service. For example, a relatively large number of components of the work machine must be removed before a technician can gain access to the sensor assembly. Having a sensor assembly which is difficult to service increases the maintenance cost of the work machine.

What is needed therefore is a traction assembly for a work machine which overcomes the above- mentioned drawback.

Disclosure of the Invention In accordance with a first embodiment of the present invention, there is provided a traction assembly of a work machine having (i) a differential housing having an axle passageway extending therethrough and (ii) an axle positioned within the axle passageway. The traction assembly includes a gear mechanically coupled to the axle. The gear includes (i) an outer peripheral surface having a plurality of sensor teeth defined therein, (ii) a first shoulder extending in a first lateral direction, and (iii) a second shoulder extending in a second direction. The traction assembly also includes a bearing assembly attached to the differential housing, wherein (i) the bearing assembly includes a first bearing member and a second bearing member, (ii) the gear is interposed between the first bearing member and the second bearing member, (iii) the first shoulder of the gear contacts a first journal surface of the first bearing member, and (iv) the second shoulder of the gear contacts a second journal surface of the second bearing member. The traction assembly further includes a sensor for detecting rotation of

the gear relative to the differential housing and generating a sensor signal in response thereto.

In accordance with a second embodiment of the present invention, there is provided a work machine. The work machine includes a differential housing having an axle passageway extending therethrough and an axle positioned within the axle passageway. The work machine also includes a gear mechanically coupled to the axle. The gear includes (i) an outer peripheral surface having a plurality of sensor teeth defined therein, (ii) a first shoulder extending in a first lateral direction, and (iii) a second shoulder extending in a second direction. The traction assembly further includes a bearing assembly attached to the differential housing, wherein (i) the bearing assembly includes a first bearing member and a second bearing member, (ii) the gear is interposed between the first bearing member and the second bearing member, (iii) the first shoulder of the gear contacts a first journal surface of the first bearing member, and (iv) the second shoulder of the gear contacts a second journal surface of the second bearing member. The traction assembly also includes a sensor for detecting rotation of the gear relative to the differential housing and generating a sensor signal in response thereto.

Brief Description of the Drawings FIG. 1 is a partial cross sectional, partial schematic view of a work machine which incorporates the present invention therein ;

FIG. 2 is a perspective view of a bearing member of a traction assembly of the work machine of FIG. 1 ; FIG. 3 is a perspective view of another bearing member of the traction assembly of the work machine of FIG. 1; FIG. 4 is a perspective view of a gear of the traction assembly of the work machine of FIG. 1 ; FIG. 5 is a side elevational view of the gear of FIG. 4 ; and FIG 6. is an enlarged fragmentary cross sectional view of the gear and an axle of the traction assembly of the work machine of FIG. 1.

Best Mode for Carrying Out the Invention While the invention is susceptible to various modifications and alternative forms, a specific embodiment thereof has been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

Referring now to FIG. 1, there is schematically shown a work machine 10 which incorporates the features of the present invention therein. Work machine 10 includes a differential housing 14 having (i) an axle passageway 16 extending therethrough and (ii) a coupling surface 50 which surrounds axle passageway 16. Work machine 10 also includes an axle 18 having a plurality of spline teeth

56 (also see FIG. 6) positioned within axle passageway 16. Work machine 10 further includes a traction assembly 12.

Referring now to FIG. 6, each adjacent pair of spline teeth 56 of axle 18 define a spline gap 62.

Spline gap 62 defines a leading spline gap surface 64 and a trailing spline gap surface 66. Spline gap 62 also defines a valley surface 70 interposed between each adjacent pair of spline teeth 56.

As shown in FIGS. 1-5, traction assembly 12 includes a gear 20, a bearing assembly 34, a sensor 44, an electronic control unit 46, and a brake assembly 48. As shown more clearly in FIGS. 4 and 5, gear 20 includes (i) an outer peripheral surface 22 having a plurality of sensor teeth 24 defined therein, (ii) a shoulder 26 extending in a lateral direction as indicated by arrow 28, and (iii) a shoulder 30 extending in a lateral direction as indicated by arrow 32. Gear 20 further includes an inner peripheral surface 52 having a plurality of spline teeth 54 formed thereon. As shown in FIG. 6, each spline tooth 54 includes a leading spline tooth surface 58 and a trailing spline tooth surface 60. Leading spline tooth surface 58 defines a lowermost edge surface 68.

As shown in FIGS. 2 and 3, bearing assembly 34 includes a bearing member 36 and a bearing member 38. In addition, each bearing member 36 and 38 has a cutout area 74 and a cut out area 76 respectively defined therein. Bearing member 36 includes a sensor bracket 72 secured thereto adjacent to cutout area 74.

Bearing members 36 and 38 also have journal surfaces 40 and 42 respectively defined thereon.

Referring now to FIG. 1, gear 20 is positioned relative to bearing assembly 34 such that gear 20 is interposed between bearing member 36 and bearing member 38. Gear 20 is further positioned relative to bearing assembly 34 such that (i) shoulder 26 of gear 20 contacts journal surface 40 of bearing member 36, and (ii) shoulder 30 of gear 20 contacts journal surface 42 of bearing member 38. Furthermore, each bearing member 36 and 38 is positioned relative to each other such that cutout areas 74 and 76 are adjacent to one another.

Bearing assembly 34 (with gear 20 interposed between bearing member 36 and 38) is secured directly to coupling surface 50 of differential housing 14 with a number of bolts 78 such that axle 18 extends through bearing member 36, gear 20, and bearing member 38 as shown in FIG. 1. In addition, bearing member 36, gear 20, and bearing member 38 are positioned relative to axle 18 such that spline teeth 54 of gear 20 are meshingly engaged with spline teeth 56 of axle 18 as shown in FIG. 6. Specifically, when a spline tooth 54 is positioned in a respective spline gap 62, (i) leading spline tooth surface 58 is respectively positioned in contact with leading spline gap surface 64 at all times during operation of traction assembly 12, and (ii) trailing spline tooth surface 60 is spaced apart from trailing spline gap surface 66 at all times during operation of traction assembly 12.

In addition, it should be understood that lowermost edge surface 68 is spaced apart from valley surface 70 at all times during operation of traction assembly 12.

It should be appreciated that having gear 20 positioned relative to bearing assembly 34, attached

to coupling surface 50, and meshingly engaged with axle 18 in the above described manner allows gear 20 to rotate relative to differential housing 14.

Specifically, having gear 20 meshingly engaged with axle 18 in the above described manner causes gear 20 to rotate relative to differential housing 14 as axle 18 rotates around a central axis 86 in a direction indicated by arrow 88.

Sensor 44 is positioned within sensor bracket 72 such that sensor 44 extends near cutout area 74 and cutout area 76. Sensor 44 is electrically coupled to electronic control unit 46 via electrical line 82 and electronic control unit 46 is electrically coupled to brake mechanism 48 via electrical line 84.

Having sensor 44 located as described above positions an end of sensor 44 at a predetermined distance from sensor teeth 24 of gear 20 such that sensor 44 can detect the rotation of gear 20 (and thus rotation of axle 18) relative to differential housing 14 and generate a sensor signal in response thereto. One sensor 44 that can be used in the present invention is available from The Morey Corporation located in Downers Grove, Illinois, U. S. A. as catalogue number CAT1440178.

Industrial Applicability During use of work machine 10 and traction assembly 12, axle 18 rotates around central axis 86 in the direction indicated by arrow 88. Rotation of axle 18 in the above described manner also causes gear 20 to rotate around central axis 86 in the direction indicated by arrow 88. Rotation of gear 20 causes sensor teeth 24 to pass by sensor 44 at a

predetermined distance which in turn causes sensor 44 to send a sensor signal to electronic control unit 46 via electrical line 82. Electronic control unit 46 then sends a brake signal to brake assembly 48 via electrical line 84 if electronic control unit 46 determines that axle 18 is coupled to a wheel (not shown) that is slipping. Brake assembly 48 applies a stopping force to oppose rotation of axle 18 in response to the brake signal. Opposing the rotation of axle 18 in a slipping situation helps increase the traction of work machine 10. However, it should be understood that electronic control unit 46 only sends a brake signal to brake assembly 48 if electronic control unit 46 determines that axle 18 is coupled to a wheel (not shown) that is slipping (e. g. if the wheel is slipping on a relatively slick surface such as gravel). Moreover, it should be understood that each axle of work machine 10 is equipped with a sensor 44, a bearing assembly 34, and a gear 20 so that electronic control unit 46 can monitor the traction status of all the wheels of work machine 10.

It should be appreciated that axle 18 tends to radially flex and bend relative to gear 20 during the use of traction assembly 12. Therefore, having spline teeth 54 and spline teeth 56 positioned relative to one another as described above in reference to FIG. 6, in particular having lowermost edge surface 68 spaced apart from valley surface 70 at all times during operation of traction assembly 12, is an advantage of the present invention. Specifically, the above described spline teeth arrangement allows the aforementioned radial movement of axle 18 relative to gear 20 (e. g. in the directions indicated by arrows

80 and 90 (see FIGS. 1 and 6)) while substantially preventing any radial loads being imparted to gear 20.

In other words, the spline teeth arrangement is "loose"enough such that it allows axle 18 to radially move or flex relative to gear 20 while preventing axle 18 from contacting gear 20 in such a manner so as to cause gear 20 to move in a radial direction (e. g. in the directions indicated by arrows 80 and 90 (see FIGS. 1 and 6)). Preventing the radial movement of gear 20 is important since sensor teeth 24 must be kept a predetermined distance away from sensor 44 in order for sensor 44 to accurately detect the rotation of gear 20. Thus, it should be understood that without the above described spline teeth arrangement, the radial movement of axle 18 would cause gear 20 to move such that sensor teeth 24 would no longer be located at the predetermined distance from sensor 44.

It should also be appreciated that securing bearing assembly 34 in direct contact with coupling surface 50 of differential housing 14 is another advantage of the present invention. Specifically, securing bearing assembly 34 in the above described manner makes bearing assembly 34, sensor 44, and gear 20 easily accessible for servicing which decreases the maintenance cost of work machine 10.

This is in contrast to other traction assembly designs that locate components of the traction assembly (e. g. the sensor) in the spindle of a wheel group of the work machine. Locating traction assembly components in the spindle makes the traction assembly difficult to service. For example, a relatively large number of components of the work machine must be removed before a technician can gain

access to the traction assembly when components thereof are located in the spindle of the wheel group.

While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description is to be considered as exemplary and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.