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BACKGROUND OF THE INVENTION 
       [0001]    The invention pertains to a road milling drum wherein the road milling drum, which carries a plurality of road milling bits, is a component of a road milling machine. More specifically, the invention pertains to an improved road milling drum wherein the road milling drum, which carries a plurality of road milling bits (or road planing bits) and is a component of the road milling machine, is capable of modification to adjust (or vary) its lateral cutting width. 
         [0002]    Over time and use, a roadway becomes worn and uneven to necessitate renovation or resurfacing thereof. A typical way to resurface the roadway is by the removal of the top layer or region of roadway material (e.g., asphaltic material or concrete or the like) by the use of a road milling machine. In other words, a road milling machine mills roadway surfaces to remove a top layer or region of material prior to resurfacing. 
         [0003]    A road milling machine comprises many components, but a major component thereof is a road milling drum. Typically, a road milling drum is a cylindrical drum that carries a plurality (e.g., sometimes hundreds) of road milling bits at the surface thereof. In this regard, U.S. Pat. No. 6,877,818 B1 to Gaertner et al. discloses a road milling drum. When in operation, the road milling machine drives the road milling bits carried by the road milling drum into the top region of the roadway to break up the top region into pieces. Many times, and especially in the case of asphaltic roadway material, a conveyor transports the pieces into a truck or the like for transport to a recycling facility. 
         [0004]    The removal of roadway material generally must satisfy pre-determined government specifications. Oftentimes, these specifications require very specific milling widths for the removal of roadway material. Further, the milling widths for a particular job may vary at different locations throughout the job site. While the contractor could use a number of road milling machines wherein each road milling machine would address a specific cutting width, such a strategy would require an inordinately large investment in road milling machines. In addition, such a strategy would tie up a number of road milling machines on one milling job. 
         [0005]    In order to address a situation wherein the milling widths for a particular job may vary at different locations throughout the job, contractors have used road milling drums with adjustable milling widths. In this regard, the following United States patent documents discloses road milling drums that possess the capability to adjust the milling width: U.S. Pat. No. 5,505,598 to Murray, U.S. Pat. No. 5,722,789 to Murray et al. and U.S. Pat. No. 6,213,560 to Lindblom. Even though the above-listed patents disclose adjustable width road milling drums that address a situation wherein the milling widths for a particular job site may vary at different locations throughout the job, these road milling drums have drawbacks. 
         [0006]    In earlier adjustable-width road milling drums, one significant drawback has been that critical regions where the drum attaches to the machine are exposed to the dirt and debris inherent in a road milling operation. These critical regions contain exposed bolt heads, threaded holes, keyways, and the like that collect dirt and debris thereby rendering it more difficult to detach the drum from the machine. Such an increase in the difficulties connected with detaching the drum from the machine increases operating costs and decrease operating efficiencies for the roadway milling operation. 
         [0007]    Earlier adjustable-width road milling drums require many drum segments in order to achieve the desired milling widths. The need to keep many drum segments on hand at the job site increases the overall expense for the roadway milling operation. 
         [0008]    It becomes apparent that there would be an advantage to provide a road milling drum that can accommodate different milling widths. It is also apparent that there would be an advantage to provide a road milling drum that can accommodate different milling widths, and wherein the critical regions where the drum attaches to the machine are protected from exposure to the dirt and debris inherent in a road milling operation. Finally, it becomes apparent that there would be an advantage to provide a road milling drum that can accommodate different milling widths without the need to use many drum segments. 
       SUMMARY OF THE INVENTION 
       [0009]    In one form thereof, the invention is a road milling drum assembly for use with a road milling machine in a roadway milling operation generating debris. The road milling drum comprises a drum core portion that carries a first road planing bit assembly. The drum core portion detachably connects to the road milling machine. The first road planing bit assembly has a first milling width. A protective cover detachably connects to the drum core portion and the road milling machine. 
         [0010]    In yet another form thereof, the invention is a road milling drum assembly for use with a road milling machine in a roadway milling operation generating debris. The road milling drum comprises a drum core portion that carries a first road planing bit assembly. The drum core portion detachably connects to the road milling machine. The first road planing bit assembly has a first milling width. A milling extension segment carries a second road planing bit assembly. The milling extension segment detachably connects to the drum core portion and the road milling machine. The second road planing bit assembly has a second milling width wherein the road milling drum has a milling width equal to the sum of the first milling width and the second milling width. 
         [0011]    In still another form thereof, the invention is a road milling drum assembly for use with a road milling machine in a roadway milling operation generating debris. The road milling drum comprises a core portion that carries a first road planing bit assembly. The core portion detachably connects to the road milling machine. The first road planing bit assembly has a first milling width. The assembly includes one of the following components selected from the group comprising: (1) a protective cover that detachably connects to the core portion and the road milling machine; or (2) a milling extension segment that carries a second road planing bit assembly wherein the milling extension segment detachably connects to the core portion and the road milling machine. The second road planing bit assembly has a second milling width wherein the road milling drum has a milling with equal to the sum of the first milling width and the second milling width. 
         [0012]    In another form thereof, the invention is a road milling drum assembly for use with a road milling machine in a roadway milling operation generating debris. The road milling drum comprises a cylindrical core portion that carries a first road planing bit assembly. The cylindrical core portion detachably connects to the road milling machine. The first road planing bit assembly has a first milling width. The assembly further includes one or more of the following components a protective cover detachably connecting to the cylindrical core portion and the road milling machine wherein the road milling drum has a milling width with equal to the first width; or a first milling extension segment carrying a second road planing bit assembly, the first milling extension segment detachably connecting to the cylindrical core portion and the road milling machine, and the second road planing bit assembly having a second milling width; or a second milling extension segment carrying a third road planing bit assembly, the second milling extension segment detachably connecting to the cylindrical core portion and the road milling machine, and the third road planing bit assembly having a third milling width. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    A brief description of the drawings that form a part of this patent application now follows: 
           [0014]      FIG. 1  is a side view of a road milling machine that uses the road milling drum of the present invention; 
           [0015]      FIG. 2  is a side cross-sectional mechanical schematic view of the upper half of the core portion without the protective cover or the milling extension attached thereto; 
           [0016]      FIG. 3  is a side cross-sectional mechanical schematic view of the upper half of the core portion with the protective cover attached thereto wherein the milling width of the road milling drum is at a minimum milling width; 
           [0017]      FIG. 4  is a side cross-sectional mechanical schematic view of the upper half of the core portion with one embodiment of the milling extension attached thereto wherein the milling width of the road milling drum is at a maximum milling width; 
           [0018]      FIG. 4A  is a cross-sectional view showing the axial connection between the core portion of the drum and the milling extension using dowel pins; and 
           [0019]      FIG. 5  is a side cross-sectional mechanical schematic view of the upper half of the core portion with another embodiment of the milling extension attached thereto wherein the milling width of the road milling drum is at an intermediate milling width. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]      FIG. 1  shows a road milling machine generally designated as  10 . Road milling machine  10  includes a machine body  12  that contains the engine and controls, as well as other components, for the overall machine. The machine body  12  rides on crawler-tracks  14  or in the alternative could ride on wheels. A conveyor  16  is operatively connected to the machine body  12  so that broken-up roadway material enters the conveyor  16  whereby it is typically transported to a dump truck or the like for removal from the job site. The machine body  12  houses the cylindrical road milling drum  18 . 
         [0021]      FIG. 2  illustrates a specific embodiment of a cylindrical road milling drum core portion generally designated as  20  of the present invention. The core portion  20  is a part of the overall road planing drum  18 . The core portion  20  is contained within the housing ( 22 ,  24 ) that is a part of the machine body  12 . 
         [0022]    A planetary gear assembly  26 , which has a radial outward projection  28 , affixes (via, e.g., bolts or the like) to the housing  22  and also affixes to the core portion  20  of the drum radially and laterally as will described in more detail hereinafter. The planetary gear assembly also provides rotational driving force from the engine (or the like) to the drum core portion  20 . 
         [0023]    A stub shaft  30 , which has a channel  32 , affixes (via, e.g., bolts or the like) to a flange  48  inside the core portion of the drum as described in more detail hereinafter. The stub shaft  30  also slides into a carrier bearing  25  in the housing  24 . The stub shaft  30  rotates within the bearing  25 . The stub shaft  30  supports the drum radially and permits the drum to rotate relative to the housing. 
         [0024]    The cylindrical drum core portion  20  also has a torque transmission area generally designated as  34 . It is preferable that the torque transmission area contain a plurality of dowels  77  that project in an axial fashion wherein these dowels engage the milling extension segments or the protective cover as described hereinafter. As described above. The engagement between the cylindrical core portion of the drum and the cylindrical milling extension segment(s) (or cylindrical protective cover) is axial in nature, which means that the projections project along in a direction parallel to the transverse axis of the drum. There should be an appreciation that in place of dowel pins, splines, keys or the like could function to provide a positive mechanical axial connection to transfer the torque from the cylindrical drum core portion  20  to the attached cylindrical component (e.g., milling extension segment). 
         [0025]    The road milling machine  10  provides power (typically via hydraulics) to the planetary gear assembly  26 . The planetary gear assembly  26  then provides torque to the drum core  20 . As described above, the connection between the cylindrical drum core  20  and the attached component such as, for example, a cylindrical milling extension segment, is axial in nature as shown especially in  FIG. 4A . This axial connection also means that the torque is applied to the cylindrical milling extension segments (see  FIGS. 4 and 5 ) in an axial fashion to provide positive transfer of rotational force. Such an axial connection also eliminates axial seams in the drum that function to interrupt or block pedestal welding. 
         [0026]    The cylindrical drum core portion  20  includes a radial outward peripheral member  42  that includes an interior radial inward projection  44  and an exterior radial inward projection  45 . The drum core portion  20  also has an integral radial inward peripheral member  46  that terminates in a flange  48 . A plurality of road planing bit assemblies attach to the surface  50  of the radial outward peripheral member  42  wherein each road planing bit assembly comprises a block (or holder)  54  and a road planing bit  56 , which preferably is rotatable about its central longitudinal axis. The road planing bit  56  is rotatably retained within a bore in the block  54 . 
         [0027]    Cylindrical drum core portion  20  detachably connects (e.g., via a plurality of bolts) at the exterior radial inward projection  45  to the planetary gear assembly  26  in the region of the radial outward projection  28 . It is at this location the planetary gear assembly drives the drum core portion. This connection is secure to provide efficient transfer of rotational force. Drum core portion  20  detachably connects (e.g., via a plurality of bolts) at the flange  48  to the stub shaft  30  in the region of the channel  32 . The connection of the drum core portion  20  to the stub shaft  30  provides stability to the drum core portion  20 . The connection between the drum core portion  20  and the planetary gear assembly  26  and the stub shaft  30  is a fluid-tight connection so that the interior volume of the drum functions as a coolant reservoir  60  for use by the planetary gear assembly  26 . 
         [0028]      FIG. 3  shows the road milling drum  18  with a cylindrical protective cover generally designated as  70  connected to the road milling drum core  20 . The road milling drum  18  is in an operable condition as shown in  FIG. 3 . Cylindrical protective cover  70  includes an elongate body  72  with an interior radial outward protection  74  at the interior end thereof and an exterior radial inward projection  80  adjacent to the exterior end  78  thereof. The protective cover  70  connects at the interior radial outward projection  74  to the drum core portion  20  at the channel  76  of interior radial inward projection  44 . More specifically, the outward projection  74  of the protective cover  70  contains bores that align with and receive dowels pins  77  that project (in an axial direction) from the channel  76  of the inward projection  44 . Further, the protective cover  70  connects (e.g., via a plurality of bolts) at the exterior radial inward projection  80  to the flange  48  of the drum core  20 , as well as to the stub shaft  30  at projection  27 . The exterior end  78  of the protective cover  70  is adjacent to a transverse flange  83  (projecting transversely inward) of housing  24 . 
         [0029]      FIG. 3  shows the road milling drum  18  in a condition in which during operation, it rotates about its transverse axis A-A and it has a milling width “B”. In this specific embodiment, the milling width “B” is the minimum milling width of the road milling drum. There should be an appreciation that the distal ends of the road planing bits  56  lie in the same plane E-E, which is generally parallel to the central axis A-A of the drum. Such an orientation facilitates an even roadway surface (or substrate) from the milling operation. Further, the radius “F” of the generally cylindrical protective cover  70  is less than the radius “G” for the drum core  20 . The existence of a non-cutting component (e.g., the protective cover) with a smaller radius than the cutting component (e.g., the drum core carrying the road planing bits) allows the drum to cut at greater depths when compared to an arrangement in which the non-cutting component has a radius generally the same as the radius of the drum core portion. 
         [0030]    There should be an appreciation that the cylindrical protective cover  70  protects the planetary gear assembly  26 , the torque transmission area  34  (including the dowels pins) and the stub shaft  30  from contamination by dirt and debris from the roadway milling operation. Further, there should be an appreciation that the points of connection between the drum core  20  and the planetary gear assembly  26 , the torque transmission area  34  and the stub shaft  30  that are impacted by a harsh operating environment are protected from contamination by dirt and debris from the roadway milling operation. 
         [0031]    As discussed earlier herein, the removal of roadway material generally must satisfy pre-determined government specifications wherein these specifications oftentimes require very specific milling widths for the removal of roadway material. Further, the milling widths for a particular job may vary at different locations throughout the job site. As described below, if there must be an increase in the milling width, the contractor/operator can easily remove the cylindrical protective cover and replace it with a cylindrical milling extension segment to achieve a greater milling width. In the case where the milling drum carries segments in addition to the drum core  20 , if there must be a decrease in the milling width, the contractor/operator can easily remove the cylindrical milling extension segment and replace it with a cylindrical protective cover or another cylindrical milling extension segment of a different milling width to achieve a smaller milling width. There should be an appreciation that in addition to the cylindrical drum core, the drum can carry a cylindrical protective cover and a cylindrical milling extension. Preferably, the dimensioning of the components should be such so that the components (including the drum core) extend along essentially the entire width of the drum. 
         [0032]    If the roadway milling operation requires a different milling width from width “B”, which in this case means an increase in the milling width from the minimum milling width, to the contractor (or operator) must remove the road milling drum  18  from the bearing to detach the protective cover  70  from the core  20 . In reference to  FIG. 4 , the contractor/operator then detachably connects one specific embodiment of the cylindrical milling extension segment generally designated as  90  to the cylindrical core  20 . The cylindrical milling extension segment  90 , which has an overall generally cylindrical geometry, has a milling extension segment body  92  that has an interior radial inward projection  94  adjacent to the interior end thereof and an exterior radial inward projection  96  adjacent to the exterior end thereof. 
         [0033]    There should be an appreciation that the points of attachment for the cylindrical milling extension segment  90  to the cylindrical core  20  are the same for the attachment of the cylindrical protective cover  70  to the cylindrical core  20 . For example, the milling extension segment  90  connects to the channel  76  of the interior radial inward projection  44 . The milling extension segment  90  connects (e.g., via a plurality of bolts or the like) at the exterior radial inward projection  96  to the flange  48  of the drum core  20  adjacent the channel  32 . The projection  96  of the milling extension segment  90  also attaches to the projection  27  of the stub shaft  30  to secure the segment  90  to the stub shaft  30 . There should be an appreciation that the milling extension segment  90  is securely attached at its opposite ends to provide it with stability. 
         [0034]    Referring to  FIG. 4A , there is shown the connection between the cylindrical milling extension segment  90  and cylindrical drum core portion  20  wherein the connection is at the channel  76  of the interior radial inward projection  44 . The inward projection  94  of segment  90  contains bores  91  that receive the dowels pins  77  that project from the channel  76  of projection  44 . Such a connection is axial in nature and provides a secure and positive driving connection to efficiently transfer the rotational force from the drum core portion  20  to the milling extension segment. 
         [0035]      FIG. 4  shows the road milling drum  18  in a condition in which during operation where it rotates about its transverse axis A-A it has a milling width “C”. In this specific embodiment, milling width “C” is the maximum milling width. The distal ends of the road planing bits  56  lie in the same plane E-E, which is generally parallel to the central axis A-A of the drum. As described above, such an orientation facilitates an even roadway surface (or substrate) from the milling operation. 
         [0036]    There should be an appreciation that the road milling drum protects the planetary gear assembly  26 , the torque transmission area  34  and the stub shaft  30  from contamination by dirt and debris from the roadway milling operation. Further, there should be an appreciation that the points of connection between the drum core  20  and the planetary gear assembly  26 , the torque transmission area  34  and the stub shaft  30  that are impacted by a harsh operating environment are protected from contamination by dirt and debris from the roadway milling operation. There should also be an appreciation that the protective cover  70  ( FIG. 3 ) and the milling extension segment  90  ( FIG. 4 ) can be attached or detached to the core drum portion  20  without draining the coolant from the coolant reservoir  60 . 
         [0037]    As mentioned above, government specifications oftentimes require very specific milling widths for the removal of roadway material so that a required milling width may be different from either minimum milling width “B” or maximum milling width “C”. The present road milling drum  18  can accommodate a situation in which the roadway milling operation requires a different milling width from either a minimum milling width “B” or a maximum milling width “C” to such as, for example, an intermediate milling width “D” (see  FIG. 5 ). 
         [0038]    In the case where the milling width must increase from the minimum milling width B″ to an intermediate milling width “D”, the contractor (or operator) must remove the road milling drum  18  from the bearing to detach the cylindrical protective cover  70  from the cylindrical core  20 . The contractor/operator then detachably connects the second embodiment of a cylindrical milling extension segment  110  to the cylindrical core  20 . The core  20  and the second embodiment of the milling extension segment  110  together have a milling width “D”. 
         [0039]    In the case where the milling width must decrease from the maximum milling width “C” to an intermediate milling width “D”, the contractor (or operator) must remove the road milling drum  18  from the bearing to detach the cylindrical milling extension segment  90  from the cylindrical core  20 . The contractor/operator then detachably connects the second embodiment of a cylindrical milling extension segment  110  to the cylindrical core  20 . The core  20  and the second embodiment of the milling extension segment  110  together have a milling width “D”. 
         [0040]    The cylindrical milling extension segment  110  has a radial outer milling extension segment body portion  112  that has an interior end  114  and an exterior end  116 . The body portion  112  has an interior radial inward projection  118  (which contains bores (not illustrated) like bores  91  in projection  94 ) adjacent to the interior end  114 . The milling extension  110  further has a radial inner body portion  120  that has an interior end  122  and an exterior end  124 . A radial arm  128  depends in a radial inward direction from radial outer body portion  112  to join with the radial inner body portion  120 . An exterior radial inward projection  130  projects in a radial inward direction from the radial inner body portion  120 . 
         [0041]    As one can appreciate, the points of attachment for the second embodiment of the cylindrical milling extensions segment  110  to the cylindrical core  20  are essentially the same as for the protective cover  70  or the milling extension segment  90 . More specifically, the milling extension segment  110  connects via the bores in the interior radial inward projection  118  that receive the dowel pins projecting from the channel  76  of the interior radial inward projection  44 . Further, the milling extension segment  110  connects (e.g., via a plurality of bolts) at the exterior radial inward projection  130  to the flange  48  of the drum core  20  adjacent the channel  32 , as well as to the stub shaft  30  at flange  27 . The exterior end  124  is adjacent to the transverse flange  83  (projecting inwardly) of the housing  24 . 
         [0042]      FIG. 5  shows the road milling drum  18  in a condition in which during operation where it rotates about its transverse axis A-A it has a milling width “D”. The distal ends of the road planing bits  56  lie in the same plane E-E, which is generally parallel to the central axis A-A of the drum. As described above, such an orientation facilitates an even roadway surface (or substrate) from the milling operation. Further, the radius “F” of the radial inner milling extension segment body portion  120  is less than the radius “G” for the drum core  20 . The existence of a non-cutting component (e.g., the body portion  120 ) with a smaller radius than the cutting component allows the drum to cut at greater depths when compared to an arrangement in which the non-cutting component has a radius generally the same as the radius of the drum core portion. 
         [0043]    There should be an appreciation that the planetary gear assembly  26 , the torque transmission area  34  and the stub shaft  30  are protected from contamination by dirt and debris from the roadway milling operation. Further, there should be an appreciation that the points of connection between the drum core  20  and the planetary gear assembly  26 , the torque transmission area  34  and the stub shaft  30  are protected from contamination by dirt and debris from the roadway milling operation. There should also be an appreciation that the protective cover  70 , the milling extension segment  90 , and the second milling extension segment  110  can attach or detach to the core drum portion  20  without draining the coolant from the coolant reservoir  60 . There should also be an appreciation that the cylindrical protective cover or the cylindrical milling extensions segments can slide off the dowels in an axial direction once disconnected from the cylindrical drum core and the stub shaft. This allows for an easier connection and disconnection of the milling extension segments (or protective cover) to the drum core. 
         [0044]    There should be an appreciation that the present invention provides an improved road milling drum that can accommodate different milling widths through the use of multiple segments. These segment are relatively easy to attach or detach from the core of the road milling drum. 
         [0045]    There should also be an appreciation that the present invention provides an improved road milling drum that can accommodate different milling widths wherein the critical regions where the drum attaches to the machine are protected from exposed to the dirt and debris inherent in a road milling operation. The core segment itself and a protective cover provide this protection when only the core segment is used to mill the roadway. The core segment and the milling extension segment provide this protection when the core segment and the milling extension segment are used to mill the roadway. 
         [0046]    Finally, it becomes apparent that there would be an advantage to provide a road milling drum that can accommodate different milling widths without the need to use many drum segments. In one situation, the road milling drum employs a core segment and one milling extension segment. However, there should be an appreciation that in other circumstances, the cylindrical drum core could carry more than one component. In essence, to accommodate certain circumstances, the operator could mix and match the components to achieve the desired milling width and milling result. 
         [0047]    The patents and other documents identified herein are hereby incorporated by reference herein. Other embodiments of the invention will be apparent to those skilled in the art from a consideration of the specification or a practice of the invention disclosed herein. It is intended that the specification and examples are illustrative only and are not intended to be limiting on the scope of the invention. The true scope and spirit of the invention is indicated by the following claims.

Summary:
A road milling drum assembly that is for use with a road milling machine. The road milling drum includes a core portion carrying a first road planing bit assembly wherein the core portion detachably connects to the road milling machine. The first road planing bit assembly has a first milling width. The assembly further including one of the following components selected from the group of: (1) a protective cover that detachably connects to the core portion and the road milling machine; or (2) a milling extension segment carrying a second road planing bit assembly wherein the milling extension segment detachably connects to the core portion and the road milling machine. The second road planing bit assembly has a second milling width wherein the road milling drum has a milling width equal to the sum of the first milling width and the second milling width.