Patent Publication Number: US-11034400-B2

Title: Drive sprocket for a tracked vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 15/381,003 filed Dec. 15, 2016, which is a continuation of Ser. No. 14/484,993 filed Sep. 12, 2014, which claims benefit of U.S. Provisional Patent Application Ser. No. 61/877,584, filed Sep. 13, 2013, and entitled “DRIVE SPROCKET FOR A TRACKED VEHICLE”, which are herein incorporated by reference in their entireties. 
    
    
     FIELD OF THE INVENTION 
     The present invention is directed to a drive sprocket, and more particularly, a drive sprocket for a tracked vehicle having a suspension. 
     BACKGROUND OF THE INVENTION 
     Track drive machines typically include those with metal or composite cleats that are connected together to form continuous loops and those constructed of reinforced polymer/rubber materials that are manufactured in endless loops. 
     Tracked vehicles are typically designed so as to produce ground pressures lower than that of wheeled vehicles. Heavy machines are typically below 15 lb/in 2 , but lightweight machines are ranging as low as 1 to 3 lb/in 2 . The stiffness of the track is selected to minimize flexing between the bogie wheels. The track is therefore kept substantially straight between the bogie wheels, idlers, and the drive sprocket to increase the efficiency associated with transference of power to the tracks and losses due to misalignment. Track tension, especially for non-metallic endless-loop configurations, must be maintained within prescribed parameters in order to prevent buckling in slack sections. 
     Drive sprockets are sometimes positioned above the ground to reduce contamination, reduce complexity in the design while effectively transmitting power to the tracks. Positioning the drive sprockets above ground also helps to prevent derailing of the track. Tracks are generally held in a constant state of tension on the drive sprocket and the roller, and this also helps to prevent derailment. 
     These offerings have limitations in performance in regard to lateral derailment of tracks, drive lug skipping (ratcheting), and backlash impacts from sprocket engagement to drive lug during traction direction load reversals. 
     A need therefore exists for a drive sprocket for a tracked vehicle in which the drive sprocket maintains closer engagement with guide lugs on track. A need also exists for a drive sprocket for a tracked vehicle that reduces the wear and increases the longevity of the guide lugs and adjacent lugs on the track. 
     BRIEF SUMMARY OF THE INVENTION 
     In one aspect of the invention, a drive sprocket for driving a track of a tracked vehicle comprises: a pair of spaced-apart inner rings, wherein the inner rings are oriented in a substantially spaced-apart manner, each of the inner rings having an outer peripheral edge; a plurality of rods attached to the inner rings adjacent to the outer peripheral edge thereof; and a pair of guide rings fixedly attached to the rods, wherein each of the guide rings is attached adjacent to an opposing end of the rods, the guide rings being oriented substantially parallel to each other and the inner rings. 
     In another aspect of the drive sprocket, a spacer is positioned between the inner rings, the spacer being fixedly attached to the inner rings. 
     In another aspect of the drive sprocket, an adapter is attached to an outwardly-directed surface of one of the pair of inner rings. 
     In another aspect of the drive sprocket, a slide ring is attached to an outwardly-directed surface of each of the guide rings. 
     In another aspect of the drive sprocket, an outwardly-directed surface of each of the guide rings is coated with a friction-reducing material. 
     In another aspect of the drive sprocket, each of the plurality of rods is spaced-apart from adjacent rods. 
     In another aspect of the drive sprocket, the plurality of rods form a plurality of clusters, wherein each of the clusters is formed of a pair of the rods and each of the cluster is spaced-apart from adjacent clusters about the peripheral edge of the inner rings. 
     In another aspect of the drive sprocket, the rods are cylindrically shaped having a circumferential surface. 
     In another aspect of the drive sprocket, a portion of the circumferential surface of the rods extend radially outward away from the outer peripheral surface of the inner rings relative to a rotational axis of the drive sprocket. 
     In another aspect of the drive sprocket, a portion of the circumferential surface of the rods extend radially outward away from the outer peripheral surface of the guide rings relative to a rotational axis of the drive sprocket. 
     In another aspect of the drive sprocket, a portion of the circumferential surface of the rods extend radially outward away from the outer peripheral surface of the inner rings relative to a rotational axis of the drive sprocket, and a portion of the circumferential surface of the rods extend radially outward away from the outer peripheral surface of the guide rings relative to a rotational axis of the drive sprocket. 
     In yet another aspect of the invention, a drive sprocket for driving a track of a tracked vehicle comprises: an interior ring, an exterior ring, and an intermediate ring situated between the interior ring and the exterior ring; the interior ring, the exterior ring, and the intermediate ring are oriented in a substantially spaced-apart manner and are parallel with one another, each of the rings having an outer peripheral surface; and a plurality of rods attached to the rings adjacent to the outer peripheral surface thereof. 
     In another aspect of the invention, the interior ring has a substantially “U” or “J” shape. 
     In another aspect of the invention, the an inner guide ring, an outer guide ring, and a base ring of the interior ring form the substantially “U” or “J” shape of the interior ring. The base ring is located between the inner guide ring and the outer guide ring. 
     In another aspect of the invention, the base ring, the inner guide ring, and a first portion of the outer guide ring of interior ring form the substantially “U” shape of the interior ring. 
     In another aspect of the invention, the exterior ring has a substantially “U” or “J” shape. 
     In another aspect of the invention, an inner guide ring, an outer guide ring, and a base ring of the exterior ring form the substantially “U” or “J” shape of the exterior ring. The base ring is located between the inner guide ring and the outer guide ring of the exterior ring. 
     In another aspect of the invention, the base ring, the outer guide ring, and a first portion of the inner guide ring of the exterior ring form the substantially “U” shape of the exterior ring. 
     In another aspect of the invention, the intermediate ring has a substantially “U” or “J” shape. 
     In another aspect of the invention, an inner guide ring, an outer guide ring, and a base ring of the intermediate ring form the substantially “U” or “J” shape of the intermediate ring. The base ring is located between the inner guide ring and the outer guide ring of the intermediate ring. 
     In another aspect of the invention, the base ring, the inner guide ring, and a first portion of the outer guide ring of the intermediate ring form the substantially “U” shape of the intermediate ring. 
     In another aspect of the invention, the “U” or “J” shape of the interior ring is configured to substantially fill the space between an interior guide lug and an interior drive lug arranged in an annular pattern on an inside surface of a track. 
     In another aspect of the invention, the “U” or “J” shape of the intermediate ring is configured to substantially fill the space between an exterior drive lug and an interior drive lug arranged in an annular pattern on an inside surface of a track. 
     In another aspect of the invention, the “U” or “J” shape of the exterior ring is configured to substantially fill the space between an exterior guide lug and an exterior drive lug arranged in an annular pattern on an inside surface of a track. 
     In another aspect of the invention, the base ring of the interior ring is further comprised of a flat outer peripheral surface located between the rods and the inner guide ring and the outer guide ring of the interior ring. 
     In another aspect of the invention, the base ring of the exterior ring is further comprised of a flat outer peripheral surface located between the rods and the inner guide ring and the outer guide ring of the exterior ring. 
     In another aspect of the invention, the base ring of the intermediate ring is further comprised of a flat outer peripheral surface located between the rods and the inner guide ring and the outer guide ring of the intermediate ring. 
     In another aspect of the invention, each of the plurality of rods is spaced-apart from adjacent rods. 
     In another aspect of the invention, the plurality of rods form a plurality of clusters, wherein each of the clusters is formed of a pair of the rods and each of the clusters is spaced apart from adjacent clusters about the peripheral edge of the inner rings. 
     In another aspect of the invention, the rods are cylindrically shaped having a circumferential surface. 
     In another aspect of the invention, a portion of the circumferential surface of the rods extends radially outward away from the outer peripheral surface of the interior ring relative to a rotational axis of the drive sprocket. 
     In another aspect of the invention, a portion of the circumferential surface of the rods extends radially outward away from the outer peripheral surface of the exterior ring relative to a rotational axis of the drive sprocket. 
     In another aspect of the invention, a portion of the circumferential surface of the rods extends radially outward away from the outer peripheral surface of the intermediate ring relative to a rotational axis of the drive sprocket. 
     In another aspect of the invention, an adapter is fixed to an outer guide ring of the interior ring, wherein the adapter is configured to be directed toward a tracked vehicle when the drive sprocket is mounted on the tracked vehicle. 
     In another aspect of the invention, a spoke assembly is fixed to the outer guide ring of the interior ring; the spoke assembly is configured to be directed away from the tracked vehicle when the drive sprocket is mounted on the tracked vehicle; the spoke assembly ring has a plurality of spokes projecting toward the radial periphery of the drive sprocket; the spokes form an acute angle with respect to the outer guide ring. 
     In another aspect of the invention, each of the spokes has a ring end, a distal end, and an intermediate position located between the ring end and the distal end; the exterior ring is fixed to the distal end of the spokes and the intermediate ring is fixed to the spokes at the intermediate position. 
     Advantages of the present invention will become more apparent to those skilled in the art from the following description of the embodiments of the invention which have been shown and described by way of illustration. As will be realized, the invention is capable of other and different embodiments, and its details are capable of modification in various respects. 
    
    
     
       BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
       These and other features of the present invention, and their advantages, are illustrated specifically in embodiments of the invention now to be described, by way of example, with reference to the accompanying diagrammatic drawings, in which: 
         FIG. 1A  is an end view of a first exemplary embodiment of a drive sprocket; 
         FIG. 1B  is a view of a first exemplary embodiment of a drive sprocket taken along line  1 B of  FIG. 1A ; 
         FIG. 1C  is a perspective view of a first exemplary embodiment of a drive sprocket; 
         FIG. 2A  is an end view of a second exemplary embodiment of a drive sprocket; 
         FIG. 2B  is a view a second exemplary embodiment of a drive sprocket taken along line  2 B of  FIG. 2A ; 
         FIG. 2C  is a perspective view of a second exemplary embodiment of a drive sprocket; and 
         FIGS. 3A-B  are perspective views of an embodiment of a drive sprocket on a tracked vehicle. 
         FIG. 4  is a perspective view of the front of a third exemplary embodiment of a drive sprocket. 
         FIG. 5  is a perspective view of the back of a third exemplary embodiment of a drive sprocket. 
         FIG. 6  is an end view of a third exemplary embodiment of a drive sprocket. 
         FIG. 7  is a close up front view of a third exemplary embodiment of a drive sprocket. 
         FIG. 8  is an isometric view of the front of a third exemplary embodiment of a drive sprocket on a tracked vehicle. 
     
    
    
     It should be noted that all the drawings are diagrammatic and not drawn to scale. Relative dimensions and proportions of parts of these figures have been shown exaggerated or reduced in size for the sake of clarity and convenience in the drawings. The same reference numbers are generally used to refer to corresponding or similar features in the different embodiments. Accordingly, the drawing(s) and description are to be regarded as illustrative in nature and not as restrictive. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about”, is not limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Range limitations may be combined and/or interchanged, and such ranges are identified and include all the sub-ranges stated herein unless context or language indicates otherwise. Other than in the operating examples or where otherwise indicated, all numbers or expressions referring to quantities of ingredients, reaction conditions and the like, used in the specification and the claims, are to be understood as modified in all instances by the term “about”. 
     “Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, or that the subsequently identified material may or may not be present, and that the description includes instances where the event or circumstance occurs or where the material is present, and instances where the event or circumstance does not occur or the material is not present. 
     As used herein, the terms “comprises”, “comprising”, “includes”, “including”, “has”, “having”, or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article or apparatus that comprises a list of elements is not necessarily limited to only those elements, but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. 
     The singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. 
     The proposal provides for metallic or composite material sprocket with a central hub with radial extensions (such as discs or spokes) to connect with teeth equally spaced in an annual arrangement. The teeth are spaced to engage the track drive lugs near their tooth roots and to match the track pitch length in a neutral or a slightly under-pitch condition. 
     The drive sprocket is provided with rod-shaped teeth that engage the traction drive lugs of the tracks close to the traction drive lug pitch line so as to reduce bending moments and stress on the drive lugs. The sprocket teeth do not appreciably “scrub” the areas between the drive lugs during traction drive load force reversals such as during machine acceleration and deceleration and turning maneuvers. One embodiment shown includes two (or more) rods to further minimize the backlash. This reduction in backlash also reduces the propensity for track drive lug skipping. In other embodiments, only one rod is present at each drive rod-tooth location. 
     The drive sprocket includes a pair of guide rings that attach to the drive rod-teeth, and they laterally engage guide lugs during turning maneuvers to prevent track derailment. These rings greatly strengthen the drive rod-teeth and help to increase the contact areas of the teeth while also reducing track deformation (flexing of the rods without the ring supports allow a crowning effect of the tracks at the sprockets). In one embodiment, these rings are equipped with low friction materials to reduce scrub friction with the guide lugs. In other embodiments, a low friction material is not present on the guide rings. 
     The following features are incorporated:
         A sprocket incorporating a central drive hub, radial extensions to connect with teeth, single rod-shaped teeth annularly spaced at the pitch-length of the track, and rings attached to the teeth   Same as above but with multiple rods at each tooth location   Same as above, but with low-friction materials coated onto or attached to the rings   Same as above but with the teeth annularly spaced at less than the pitch-length of the track, up to 1% under-pitch       

     In the embodiment illustrated in  FIGS. 1A-C , the drive sprocket  10  includes a pair of substantially circular inner rings  12 . A spacer  14  is positioned between the pair of inner rings  12  to allow the inner rings  12  to be spaced apart. The thickness of the spacer  14  is between about 0.10 inches and about 3.0 inches. The spaced-apart inner rings  12  provide lateral stiffness to the drive sprocket  10 , particularly with respect to the lateral forces experienced during a turn of the vehicle. The spacer  14  is sandwiched between the inner rings  12 . An adapter  16  is positioned adjacent to the outwardmost inner ring  12  relative to the vehicle when the drive sprocket  10  is operatively connected to the vehicle. The adapter  16  is configured to engage a drive shaft or other rotatable shaft that operatively transfers rotation from the engine to the drive sprocket  10 . When the drive sprocket  10  is installed onto the drive shaft, the adapter  16  is directed away from the vehicle. 
     In an embodiment, the inner rings  12  and the spacer  14  can be formed as a single member having an equivalent thickness. The spacer  14  allows the inner rings  12  to provide the structural integrity to the rods  18  while reducing the weight of the drive sprocket  10 . In a similar manner, the adapter  16  can also be formed as having a diameter that is substantially the same as the inner rings  12 . The spacer  14  and adapter  16  are attached to the inner rings  12  to allow the drive sprocket  10  to be attached to the drive shaft from an engine while transferring the rotational force to the inner rings  12 . In another embodiment, the inner rings  12 , spacer  14 , and adapter  16  all include a common aperture shaped to receive the drive shaft (not shown) that provides the rotational power to the drive sprocket  10 . 
     A plurality of rods  18  are positioned about the radial periphery of the spaced-apart inner rings  12 , as shown in  FIGS. 1A-C . The rods  18  are connected to the inner rings  12  such that a portion of each rod  18  extends laterally away from each of the inner rings  12  in a substantially parallel manner relative to the rotational axis of the drive sprocket  10 . In an embodiment, a pair of rods  18  are positioned immediately adjacent to each other to form a cluster, and each cluster is spaced apart about the periphery of the inner rings  12 . In another embodiment, each rod  18  is spaced apart from each adjacent rod about the periphery of the inner rings  12 . In an embodiment, the rods  18  are cylindrical, having a circular cross-sectional shape. It should be understood by one of ordinary skill in the art that the cross-sectional shape of the rods  18  can be any shape such as circular, square, triangular, or the like. The rods  18  are configured to engage the guide lugs positioned on the inner surface of a track. In an embodiment, as is shown in  FIG. 1A , a portion of the circumferential surface of the rods  18  extend radially outward away from the outer peripheral surface  12   a  of the inner rings  12  relative to the rotational axis of the drive sprocket  10 . As such, the rods  18  extend beyond the inner rings  12  to ensure engagement with the base of each guide lug of the track. The rods  18  are oriented substantially perpendicular to the flat inner rings  12  to which they are attached. 
     A pair of guide rings  20  are attached to the rods  18 , wherein each guide ring  20  is attached to adjacent ends of the rods  18  in a spaced-apart manner, as shown in  FIGS. 1A-C . The guide rings  20  are single-piece annular members oriented in a substantially parallel manner on opposing sides of the spacer  14  and adapter  16 . The outwardly-directed surface of the guide rings  20  are positioned outwardly from the rods  18 . Similar to the inner rings  12 , the rods  18  extend radially outward relative to the outer peripheral surface  20   a  of the guide rings  20 . 
     In an embodiment, the outwardly directed surfaces of the guide rings  20  are coated with a reduced-friction material such as Teflon®, silicon, or the like. The reduced-friction material can be a spray-on type, adhesive type, or other manner of coating the guide rings  20 . The reduced-friction material prevents rubbing and wear against adjacent lugs on the track when operated during dry conditions. However, if the vehicle is being used in a wet environment or on grass which may act as a lubricant, the reduced-friction material is optional. In another embodiment, a slide ring  22  which has low friction, wherein the outer peripheral edge of the slide ring  22  is rounded to reduce the impact against the adjacent lugs of the track. The slide ring  22  is formed of nylon 6/6 or other reduced-friction material. The slide ring  22  is formed as a continuous, single-piece annular member having substantially the same size and shape as the guide ring  20  to which it is attached. The slide ring  22  is attached to the guide ring  20  by way of a plurality of screws, but any other fastening mechanism can be used to attach each slide ring  22  to an outwardly-directed surface of a corresponding guide ring  20 . 
     The inner rings  12  and the guide rings  20  can be formed of aluminum, steel, or any other material sufficient to withstand the stresses experienced during driving a tracked vehicle, particularly the lateral stresses experienced during a turn. 
     In the embodiment illustrated in  FIGS. 2A-C , the drive sprocket  10  includes a pair of substantially circular inner rings  12 . A spacer  14  is positioned between the pair of inner rings  12  to allow the inner rings  12  to be spaced apart. The thickness of the spacer  14  is between about 0.10 inches and about 3.0 inches. The spaced-apart inner rings  12  provide lateral stiffness to the drive sprocket  10 , particularly with respect to the lateral forces experienced during a turn of the vehicle. The spacer  14  is sandwiched between the inner rings  12 . An adapter  16  is positioned adjacent to the outwardmost inner ring  12  relative to the vehicle when the drive sprocket  10  is operatively connected to the vehicle. The adapter  16  is configured to engage a drive shaft or other rotatable shaft that operatively transfers rotation from the engine to the drive sprocket  10 . When the drive sprocket  10  is installed onto the drive shaft, the adapter  16  is directed away from the vehicle. 
     In an embodiment, the inner rings  12  and the spacer  14  can be formed as a single member having an equivalent thickness. The spacer  14  allows the inner rings  12  to provide the structural integrity to the rods  18  while reducing the weight of the drive sprocket  10 . In a similar manner, the adapter  16  can also be formed as having a diameter that is substantially the same as the inner rings  12 . The spacer  14  and adapter  16  are attached to the inner rings  12  to allow the drive sprocket  10  to be attached to the drive shaft from an engine while transferring the rotational force to the inner rings  12 . In another embodiment, the inner rings  12 , spacer  14 , and adapter  16  all include a common aperture shaped to receive the drive shaft (not shown) that provides the rotational power to the drive sprocket  10 . 
     A plurality of rods  18  are positioned about the radial periphery of the spaced-apart inner rings  12 , as shown in  FIGS. 2A-C . The rods  18  are connected to the inner rings  12  such that a portion of each rod  18  extends laterally away from each of the inner rings  12  in a substantially parallel manner relative to the rotational axis of the drive sprocket  10 . In an embodiment, each rod  18  is spaced apart from each adjacent rod about the periphery of the inner rings  12 . In an embodiment, the rods  18  are cylindrical, having a circular cross-sectional shape. It should be understood by one of ordinary skill in the art that the cross-sectional shape of the rods  18  can be any shape such as circular, square, triangular, or the like. The rods  18  are configured to engage the guide lugs positioned on the inner surface of a track. In an embodiment, a portion of the circumferential surface of the rods  18  extend radially outward away from the outer peripheral surface  12   a  of the inner rings  12  relative to the rotational axis of the drive sprocket  10 . As such, the rods  18  extend beyond the inner rings  12  to ensure engagement with the base of each guide lug of the track. The rods  18  are oriented substantially perpendicular to the flat inner rings  12  to which they are attached. 
     A pair of guide rings  20  are attached to the rods  18 , wherein each guide ring  20  is attached to adjacent ends of the rods  18  in a spaced-apart manner, as shown in  FIGS. 2A-C . The guide rings  20  are single-piece annular members oriented in a substantially parallel manner on opposing sides of the spacer  14  and adapter  16 . The outwardly-directed surface of the guide rings  20  are positioned outwardly from the rods  18 . Similar to the inner rings  12 , the rods  18  extend radially outward relative to the outer peripheral surface  20   a  of the guide rings  20 . 
     In some embodiments, the outwardly directed surfaces of the guide rings  20  are not coated with a reduced-friction material, nor are guide rings  20  equipped with slide ring  22 . Therefore, the reduced friction material and slide ring  22  are optional for guide rings  20 . 
     The inner rings  12  and the guide rings  20  can be formed of aluminum, steel, or any other material sufficient to withstand the stresses experienced during driving a tracked vehicle, particularly the lateral stresses experienced during a turn. 
       FIGS. 3A-B  show an embodiment of drive sprocket  10  on a tracked vehicle. As was stated above, each track  30  of tracked vehicle has a plurality of drive lugs  32  arranged in an annular pattern on the inside surface  31  of track  30 . Accordingly, in operation, rods  18  of drive sprocket  10  engage a drive lug  32  where drive lug  32  meets inside surface  31  of track  30 , thereby rods  18  engage the traction drive lugs  32  of tracks  30  close to the traction drive lug pitch line, so as to reduce bending moments and stress on the drive lugs  32 . 
     Further, the proposal provides for embodiments of a drive sprocket constructed of metallic or composite material with u-shaped rings to connect with rods equally spaced in an annual arrangement. The rods are spaced to engage the track drive lugs near their tooth roots to match the track pitch length in a neutral or a slightly under pitch condition. 
     The following features are incorporated:
         Address off-center mounting of said drive sprocket to the drive hub   Rings with radius corners (U-shape) to improve reaction to guide &amp; drive lugs
           U-shape with radius corners guides lugs into self-alignment   U-shape adds additional vertical guide rings   U-shape with “flat” areas between the guide rings provide additional support to the track and structural strength to the drive sprocket   
               

     In the embodiment illustrated in  FIGS. 4-5 , the drive sprocket  10  includes an interior ring  40 , exterior ring  50 , and an intermediate ring  60  located between said interior ring  40  and exterior ring  50 . Said interior ring  40 , exterior ring  50 , and intermediate ring  60  are spaced apart and centered about the rotational axis of the drive sprocket  10 . Interior ring  40  is the inner most ring relative to the tracked vehicle when drive sprocket  10  is installed onto the drive shaft of the tracked vehicle. Exterior ring  50  is the outer most ring relative to the tracked vehicle when drive sprocket  10  is installed onto the drive shaft of the tracked vehicle. 
     Interior ring  40  has an inner guide ring  41 , an outer guide ring  43 , and a base ring  47 . Inner guide ring  41  and outer guide ring  43  are vertically oriented rings relative to the rotational axis of the drive sprocket  10 . Further, inner guide ring  41  and outer guide ring  43  are substantially parallel. 
     Inner guide ring  41  is the inner most ring of interior ring  40  and outer guide ring  43  is the outer most ring of interior ring  40  relative to the tracked vehicle when drive sprocket  10  is installed onto the drive shaft (not shown) of the tracked vehicle. Base ring  47  is located between interior ring  40  and outer guide ring  43 . 
     Base ring  47  is a ring having a horizontally oriented width relative to the rotational axis of the drive sprocket  10 . Base ring  47  extends in a substantially parallel manner relative to the rotational axis of sprocket  10 , thereby bridging between inner guide ring  41  and outer guide ring  43 . Further, inner guide ring  41  and outer guide ring  43  are substantially perpendicular to base ring  47 . A base portion  41   c  of inner guide ring  41  is connected to first side  47   a  of base ring  47 . A base portion  43   c  of outer guide ring  43  is connected to second side  47   b  of base ring  47 . The transitions between inner guide ring  41  and base ring  47 , and outer guide ring  43  and base ring  47  are radius corners. 
     An adapter  16  is fixed to the inside face  43   e  of outer guide ring  43  and directed toward the tracked vehicle. Adapter  16  and outer guide ring  43  share a common center hole  44  and lug holes  45 . Adapter  16  and outer guide ring  43  are centered about the rotational axis of the drive sprocket  10 . Adapter  16  and outer guide ring  43  are configured to engage a drive shaft or other rotatable shaft that operatively transfers rotation from the engine to the drive sprocket  10 . 
     In some embodiments, outer guide ring  43  has a plurality of lightening apertures  46 , which reduce the weight of outer guide ring  43 , while providing structural integrity for drive sprocket  10 . In some embodiments, adapter  16  can be formed as having a diameter substantially the same as outer guide ring  43 . In some embodiments, adapter  16  has lightening apertures  46 . 
     As can be seen, inner guide ring  41 , outer guide ring  43 , and base ring  47  of interior ring  40  form substantially a “J” shape, or a “U” shape with an elongated leg on one side of the “U”. Stated alternatively, inner guide ring  41 , outer guide ring  43 , and base ring  47  form the cross-section of interior ring  40 , which in some embodiments is substantially a “J” shape or a “U” shape with an elongated leg on one side of the “U”. 
     Further, outer guide ring  43  has a first portion  43   a  and a second portion  43   b . The first portion  43   a  extends from base portion  43   c  toward the center of outer guide ring  43  for a vertical distance “A”, which is substantially equal to the distance between the base portion  41   c  and interior edge  42  of inner guide ring  41 . Stated alternatively, the height of the first portion  43   a  of outer guide ring  43  is substantially equal to the height of inner guide ring  41 . Second portion  43   b  extends from center hole  44  to first portion  43   a . Accordingly, as can be seen, in some embodiments, first portion  43   a  of outer guide ring  43 , base ring  47 , and inner guide ring  41  of interior ring  40  form substantially a “U” shape. Stated alternatively, in some embodiments, first portion  43   a  of outer guide ring  43 , base ring  47 , and inner guide ring  41  form substantially a “U” shape cross-section of interior ring  40 . 
     In some embodiments, outer guide ring  43  and inner guide ring  41  of interior ring  40  are substantially the same height, thereby outer guide ring  43 , inner guide ring  41 , and base ring  47  form substantially a “U” shape. Stated alternatively, in some embodiments, outer guide ring  43  and inner guide ring  41  of interior ring  40  are substantially the same height, thereby, in such embodiments, outer guide ring  43 , inner guide ring  41 , and base ring  47  form substantially a “U” shape cross-section of interior ring  40 . 
     A spoke assembly  70  is fixed to the outside face  43   d  of outer guide ring  43  and directed away from the tracked vehicle when drive sprocket is installed onto the drive shaft. Spoke assembly  70  has a spoke assembly ring  71  fixed to outer guide ring  43 . Spoke assembly  70  and spoke assembly ring  71  are centered about the rotational axis of the drive sprocket  10 . 
     Spoke assembly ring  71  has a plurality of spokes  72  projecting toward the radial periphery of drive sprocket  10 . Spokes  72  form an acute angle with respect to outer guide ring  43 . Each spoke  72  has a ring end  73  located adjacent to spoke assembly ring  71  and a distal end  75  located opposite ring end  73 . Distal end  75  of spoke  72  has a tab  76 . Slot  74  is located along spoke  72  between distal end  75  and ring end  73 . 
     Turning now to exterior ring  50 , exterior ring  50  has an inner guide ring  51 , an outer guide ring  55 , and a base ring  57 . Inner guide ring  51  and outer guide ring  55  are vertically oriented rings relative to the rotational axis of the drive sprocket  10 . Further, inner guide ring  51  and outer guide ring  55  are substantially parallel. 
     Inner guide ring  51  is the inner most ring of exterior ring  50  and outer guide ring  55  is the outer most ring of exterior ring  50  relative to the tracked vehicle when drive sprocket  10  is installed onto the drive shaft of the tracked vehicle. Base ring  57  is located between inner guide ring  51  and outer guide ring  55 . 
     Base ring  57  is a ring having a horizontally oriented width relative to the rotational axis of the drive sprocket  10 . Base ring  57  extends in a substantially parallel manner relative to the rotational axis of sprocket  10 , thereby bridging between inner guide ring  51  and outer guide ring  55 . Further, inner guide ring  51  and outer guide ring  55  are oriented perpendicular to base ring  57 . A base portion  51   c  of inner guide ring  51  is connected to first side  57   a  base ring  57 . A base portion  55   c  of outer guide ring  55  is connected to second side  57   b  of base ring  57 . The transitions between inner guide ring  51  and base ring  57 , and outer guide ring  55  and base ring  57  are radius corners. 
     Inner guide ring  51  has an interior edge  52 . Inner guide ring  51  has recesses  53  positioned radially about interior edge  52 . The radial positions of recesses  53  correspond to the radial positions of the distal end  75  of spokes  72  with tab  76 , such that each tab  76  is fitted into a corresponding recess  53 . Accordingly, as can be seen, distal end  75  of spokes  72  is attached to inner guide ring  51  at interior edge  52 . 
     As can be seen, inner guide ring  51 , outer guide ring  55 , and base ring  57  of exterior ring  50  form substantially a “J” shape, or a “U” shape with an elongated leg on one side of the “U”. Stated alternatively, inner guide ring  51 , outer guide ring  55 , and base ring  57  form the cross-section of exterior ring  50 , which in some embodiments is substantially a “J” shape, or a “U” shape with an elongated leg on one side of the “U”. 
     Further, inner guide ring  51  has a first portion  51   a  and a second portion  51   b . The first portion  51   a  extends from base portion  51   c  toward the center of inner guide ring  51  for a vertical distance “B”, which is substantially equal to the distance between the base portion  55   c  and interior edge  56  of outer guide ring  55 . Stated alternatively, the height of the first portion  51   a  of inner guide ring  51  is substantially equal to the height of outer guide ring  55 . Second portion  51   b  extends from interior edge  52  to first portion  43   a . Accordingly, as can be seen, in some embodiments, first portion  51   a  of inner guide ring  51 , base ring  57 , and outer guide ring  55  of exterior ring  50  form substantially a “U” shape. Stated alternatively, first portion  51   a  of inner guide ring  51 , base ring  57 , and outer guide ring  55  form substantially a “U” shape cross section of exterior ring  50 . 
     In some embodiments, outer guide ring  55  and inner guide ring  51  of exterior ring  50  are substantially the same height, thereby outer guide ring  55 , inner guide ring  51 , and base ring  57  form substantially a “U” shape. Stated alternatively, in some embodiments, outer guide ring  55  and inner guide ring  51  of exterior ring  50  are substantially the same height, thereby, in such embodiments, outer guide ring  55 , inner guide ring  51 , and base ring  57  form substantially a “U” shape cross-section of exterior ring  50 . 
     Turning now to intermediate ring  60 , intermediate ring  60  has an inner guide ring  61 , an outer guide ring  63 , and a base ring  66 . Inner guide ring  61  and outer guide ring  63  are vertically oriented rings relative to the rotational axis of the drive sprocket  10 . Further, inner guide ring  61  and outer guide ring  63  are substantially parallel. 
     Inner guide ring  61  is the inner most ring of intermediate ring  60  and outer guide ring  63  is the outer most ring of intermediate ring  60  relative to the tracked vehicle when drive sprocket  10  is installed onto the drive shaft of the tracked vehicle. Base ring  66  is located between inner guide ring  61  and outer guide ring  63 . 
     Base ring  66  is a ring having a horizontally oriented width relative to the rotational axis of the drive sprocket  10 . Base ring  66  extends in a substantially parallel manner relative to the rotational axis of sprocket  10 , thereby bridging between inner guide ring  61  and outer guide ring  63 . Further, inner guide ring  61  and outer guide ring  63  are oriented perpendicular to base ring  66 . A base portion  61   c  of inner guide ring  61  is connected to first side  66   a  of base ring  66 . A base portion  63   c  of outer guide ring  63  is connected to second side  66   b  of base ring  66 . The transitions between inner guide ring  61  and base ring  66 , and outer guide ring  63  and base ring  66  are radius corners. 
     Outer guide ring  63  has an interior edge  64 . Outer guide ring  63  has tabs  65  positioned radially about interior edge  64 . The radial positions of tabs  65  correspond to the radial positions of slots  74  of spokes  72 , such that each tab  65  is fitted into a corresponding slot  74  located at an intermediate position  77  on spoke  72  between ring end  73  and distal end  75 . Accordingly, as can be seen, intermediate positions  77  of spokes  72  are attached to outer guide ring  63  at interior edge  64 . 
     As can be seen, inner guide ring  61 , outer guide ring  63 , and base ring  66  of intermediate ring  60  form substantially a “J” shape, or a “U” shape with an elongated leg on one side of the “U”. Stated alternatively, inner guide ring  61 , outer guide ring  63 , and base ring  66  form the cross-section of intermediate ring  60 , which in some embodiments is substantially a “J” shape, or a “U” shape with an elongated leg on one side of the “U”. 
     Further, outer guide ring  63  has a first portion  63   a  and a second portion  63   b . The first portion  63   a  extends from base portion  63   c  toward the center of outer guide ring  63  for a vertical distance of “C”, which is substantially equal to the distance between base portion  61   c  and interior edge  62  of inner guide ring  61 . Stated alternatively, the height of the first portion  63   a  of outer guide ring  63  is substantially equal to the height of inner guide ring  61 . Second portion  63   b  extends from interior edge  64  to first portion  63   a . Accordingly, as can be seen, in some embodiments, first portion  63   a  of outer guide ring  63 , base ring  66 , and inner guide ring  61  of intermediate ring  60  form substantially a “U” shape. Stated alternatively, first portion  63   a  of outer guide ring  63 , base ring  66 , and inner guide ring  61  form substantially a “U” shape cross-section of intermediate ring  60 . 
     In some embodiments, outer guide ring  63  and inner guide ring  61  of intermediate ring  60  are substantially the same height, thereby outer guide ring  63 , inner guide ring  61 , and base ring  66  form substantially a “U” shape. Stated alternatively, in some embodiments, outer guide ring  63  and inner guide ring  61  of intermediate ring  60  are substantially the same height, thereby, in such embodiments, outer guide ring  63 , inner guide ring  61 , and base ring  66  form substantially a “U” shape cross-section of intermediate ring  60 . 
     Turning to  FIG. 8 , a plurality of rods  18  are positioned about the radial periphery of the interior ring  40 , exterior ring  50 , and intermediate ring  60  of drive sprocket  10 . The rods  18  are connected to the interior ring  40 , exterior ring  50  and intermediate ring  60  such that a portion of each rod  18  extends laterally away from each of the interior ring  40 , exterior ring  50 , and intermediate ring  60  in a substantially parallel manner relative to the rotational axis of the drive sprocket  10 . In an embodiment, a pair of rods  18  are positioned immediately adjacent to each other to form a cluster, and each cluster is spaced apart about the periphery of the interior ring  40 , exterior ring  50  and intermediate ring  60 . In an embodiment, the rods  18  are cylindrical, having a circular cross-sectional shape. It should be understood by one of ordinary skill in the art that the cross-sectional shape of the rods  18  can be any shape such as circular, square, triangular, or the like. The rods  18  are configured to engage the guide lugs  32  positioned on the inner surface  31  of track  30 . In an embodiment, rods  18  do not extend beyond inner guide ring  41  of interior ring  40  and outer guide ring  55  of exterior ring  50  relative to the rotational axis of drive sprocket  10 . 
     Turning to  FIGS. 4, 6, and 8 , in an embodiments rods  18  extend beyond the radial periphery of interior ring  40 , exterior ring  50 , and intermediate ring  60 . Stated alternatively, the rods  18  extend beyond the outer peripheral surface  48  of the base ring  47  of interior ring  40 , outer peripheral surface  58  of the base ring  57  of exterior ring  50 , and outer peripheral surface  67  of the base ring  66  of intermediate ring  60 . As such, the rods  18  extending beyond outer peripheral surfaces  48 ,  58 ,  67  ensure engagement with the base of each guide lug  32  of track  30 . Further, outer peripheral surfaces  48 ,  58 ,  67  of base rings  47 ,  57 , and  66  provide flat areas between rods  18  and the inner and outer guide rings  41  and  43  of interior ring  40 , the inner and outer guide rings  51  and  55  of exterior ring  50 , and inner and outer guide rings  61  and  63  of intermediate ring  60  of drive sprocket  10 . The flat areas of outer peripheral surfaces  48 ,  58 ,  67  provide additional support to track  30  and structural strength to drive sprocket  10 . 
     Drive sprocket  10  can be formed of aluminum, steel, or any other material sufficient to withstand the stresses experienced during driving a tracked vehicle, particularly the lateral stresses experienced during a turn. 
     Turning to  FIG. 7 , in some embodiments, the distal end  75  of spokes  72  is fixed to inner guide ring  51  of exterior ring  50  by welding tab  76  to recess  53 . Further, in some embodiments, the remainder of distal end  75  abutting of interior edge  52  is also welded to interior edge  52 . Additionally, in some embodiments, the intermediate position  77  of spokes  72  is fixed to outer guide ring  63  of intermediate ring  60  by welding tab  65  protruding through slot  74  to spoke  72  at intermediate position  77 . 
     As was stated above, turning to  FIG. 8 , each track  30  of tracked utility vehicle has a plurality of drive lugs  32  arranged in an annular pattern on the inside surface  31  of track  30 . Accordingly, in operation, rods  18  of drive sprocket  10  engage a drive lug  32  of tracks  30  close to the traction drive lug pitch line, so as to reduce bending moments and stress on the drive lugs  32 . Further, the “U” and/or “J” shape of the interior ring  40 , exterior ring,  50 , and intermediate ring  60  of drive sprocket  10  substantially fill the empty space between drive lugs  32 , thereby squaring up rods  18  to drive lugs  32 , which further reduces bending moments and stresses on the drive lugs  32  of tracks  30 . 
     Further, as was stated above, the “U” or “J” shape of interior ring  40  substantially fills the space between interior guide lug  33   b  and interior drive lug  32   b . Further, the “U” or “J” shape of intermediate ring  60  substantially fills the space between exterior drive lug  32   a  and interior drive lug  32   b . Additionally, the “U” or “J” shape of exterior ring  50  substantially fills the space between exterior guide lug  33   a  and exterior drive lug  32   a.    
     Additionally, turning to  FIGS. 4 and 8 , in some embodiments, discontinuities  80 , as seen in  FIG. 4 , introduced into interior ring  40 , exterior ring,  50 , and intermediate ring  60  of drive sprocket  10  during the metal shaping process are filled in via welding to increase the rigidity of interior ring  40 , exterior ring,  50 , and intermediate ring  60 , and drive sprocket  10 .  FIG. 8  shows an embodiment of drive sprocket  10  with filled/welded discontinuities  80 .