Abstract:
A cutting machine and a method of using the cutting machine includes a cutting apparatus having a cutting device, a jackshaft sheave, an endless belt and an engine sheave. The cutting machine may have a jackshaft sheave, which is rotatably connected to the cutting instrument with the endless belt disposed about the jackshaft and engine sheaves. An engine includes a flywheel with an interface, which are configured for powering the cutting apparatus. A shaft assembly transfers energy from the flywheel of the engine to the engine sheave. The shaft assembly includes a shaft plate, a stub shaft and a coupling plate. The shaft plate is connected to the coupling plate and defines a shaft aperture with the stub shaft disposed in the shaft aperture. The stub shaft depends from the shaft aperture and is rotatably connected to the engine sheave. The coupling plate includes a coupling rotatably connected to the interface. The coupling defines a coupling chamber in which another end of the stub shaft depends and is connected in the coupling chamber such that a rotation of the coupling rotates the stub shaft to rotate the endless belt about the jackshaft and engine sheaves to operate the cutting apparatus.

Description:
FIELD OF THE INVENTION 
   This invention relates to cutting machines, particularly stump grinders and wood chippers. 
   BACKGROUND OF THE INVENTION 
   Stump grinding machines are used widely for removing tree stumps using a grinding wheel, a cutting chain or other cutting instrument. The grinding wheel, for instance, is swept back and forth across a tree stump. With each sweep, the grinding wheel is lowered incrementally until the stump is removed. The final sweeps of the grinding wheel may be below ground level to ensure that the entire stump has been eliminated. 
   Power to drive the grinding wheel is derived from an engine, usually a gasoline or diesel engine, installed on the grinding machine. The conventional grinding machine uses a power train that directly connects the engine to the grinding wheel to transfer the engine power to the grinding wheel. If the grinding wheel becomes jammed below ground level, for instance, while removing the tree stump, an overtorque situation can occur. Such a situation can transfer shear and overload forces to the engine, particularly its crankshaft, which can result in an engine failure that is costly to repair or may require replacement of the engine. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention is directed in general to a cutting machine, which includes a drive assembly that connects an engine to a cutting apparatus. The drive assembly acts an operational interface or flexible coupling between the engine and the cutting apparatus to prevent damage to the engine if the cutting apparatus becomes overloaded. The component parts of the invention are simple and economical to manufacture, assemble and use, and other advantages of the invention will be apparent from the following description and the attached drawings, or can be learned through practice of the invention. 
   According to an aspect of the invention, a cutting machine includes a cutting apparatus for cutting a workpiece and an engine for powering the cutting apparatus. The workpiece can be a material such as wood, leaves, grasses and combinations of these materials. The cutting apparatus can chip, shred, grind or mulch the material. 
   In this aspect of the invention, a shaft assembly is provided to transfer energy from the engine to the cutting apparatus. The shaft assembly includes a shaft plate, a stub shaft and a coupling plate. The shaft plate is connected to the engine, and the coupling plate is positioned between the engine and the shaft plate. The shaft plate defines a shaft aperture through which the stub shaft extends. The stub shaft has a first end and an opposing second end defining a longitudinal axis. The first end extends from the shaft aperture and is connected to the cutting apparatus. Also in this aspect, the first end of the stub shaft defines at least one channel disposed parallel to the longitudinal axis. The coupling plate includes a coupling connected to the engine. The coupling plate includes a coupling chamber in which the second end of the stub shaft is connected such that a rotation of the coupling rotates the stub shaft to operate the cutting apparatus. 
   The cutting machine in this aspect of the invention further includes an engine sheave and a bushing. The engine sheave defines at least one annular race thereon for respective engagement with the endless belt. Additionally, the engine sheave defines a bushing aperture in which the bushing is located. A key extends from the bushing into the channel of the stub shaft to couple the engine sheave and the stub shaft together. 
   The cutting machine can include a jackshaft sheave defining at least one complementary annular race thereon for respective engagement with the endless belt, which is engaged with the annular race of the engine sheave noted above. The jackshaft sheave is rotatably connected to the cutting apparatus such that the rotation of the coupling rotates the stub shaft to rotate the engine and jackshaft sheaves to operate the cutting apparatus. 
   Also in this aspect of the invention, the second end of the stub shaft defines an outer surface having a plurality of splines depending radially therefrom. The splines are disposed parallel to the longitudinal axis of the stub shaft. The coupling chamber of the coupling defines an inner surface having a plurality of complementary splines depending inwardly therefrom and disposed parallel to the longitudinal axis, each of the complementary splines further disposed adjacent respective ones of the plurality of splines when the second end of the stub shaft is inserted in the coupling chamber of the coupling. 
   Further in this aspect of the invention, the flywheel is rotatably engaged with the coupling, and the splines and the complementary splines, which are engaged in the coupling chamber, are formed to fail prior to failure of an engine crankshaft of the engine. Additionally, the cutting machine in this aspect also includes a plurality of grommets, which are located about the coupling. The grommets are also formed to fail with or before the splines prior to failure of the engine crankshaft of the engine. 
   The cutting machine in this aspect of the invention can also include means for maneuvering the cutting machine, such as a locomotion apparatus selected from a wheel, an endless track and combinations of such devices. The means for maneuvering can further include a control system. 
   The cutting machine can include at least one lubrication or grease fitting in liquid communication with the shaft assembly. A first grease fitting, for instance, can be in liquid communication with the stub shaft to communicate a quantity of grease between the splines of the stub shaft and the coupling chamber to relieve friction when the stub shaft rotates. A second grease fitting, for instance, can be in liquid communication with the stub shaft to communicate a quantity of grease to a plurality of bearings located around the stub shaft in a housing chamber through which the stub shaft at least partially extends. 
   In another aspect of the invention, a shaft assembly for transferring energy from a power plant of a cutting machine to a cutting apparatus of the cutting machine is provided. In this aspect, the shaft assembly includes a shaft housing with a chamber therein, a stub shaft rotatably disposed in the chamber; and a coupling plate connected to the shaft housing. The coupling plate has a coupling with a coupling chamber therein. The stub shaft has a first end and an opposing second end defining a longitudinal axis. The first end extends from the chamber and is rotatably connected to the cutting apparatus. The second end extends from the chamber and is connected in the coupling chamber such that a rotation of the coupling rotates the stub shaft to operate the cutting apparatus. In this aspect, the flywheel is rotatably engaged with the coupling, and the stub shaft will fail before failure of a crankshaft in the engine. 
   This aspect of the invention also includes a plurality of bearings. Moreover, the shaft housing defines an inner race therein, and the bearings are rotationally disposed in the inner race and about an exterior surface of the stub shaft. The bearings rotate about the exterior surface of the stub shaft relative to the chamber. The shaft assembly in this aspect also includes at least one lubrication fitting in liquid communication with the shaft assembly to lubricate components in the chambers discussed above. 
   In yet another aspect of the invention, a cutting machine includes a cutting apparatus with a cutting device, an endless belt and an engine sheave. If the cutting machine is a stump grinder, it can also include a jackshaft sheave. The jackshaft sheave is rotatably connected to the cutting instrument with the endless belt disposed about the jackshaft and engine sheaves. Also included in this aspect is an engine with a flywheel having an interface for powering the cutting apparatus. 
   Additionally in this aspect of the invention, a shaft assembly is provided for transferring energy from the flywheel of the engine to the engine sheave. The shaft assembly includes a shaft plate, a stub shaft and a coupling plate. The shaft plate is connected to the coupling plate and defines a shaft aperture therethrough. The stub shaft in this aspect is located in the shaft aperture and has a first end with an opposing second end defining a longitudinal axis. The first end extends from the shaft aperture and is rotatably connected to the engine sheave. The coupling plate includes a coupling rotatably connected to the interface. The coupling has a coupling chamber therein, and the second end of the stub shaft extends from the shaft aperture and is connected in the coupling chamber such that a rotation of the coupling rotates the stub shaft to rotate the endless belt about the jackshaft and engine sheaves to operate the cutting apparatus. 
   The second end of the stub shaft in this aspect of the invention defines an outer surface having a plurality of splines depending radially therefrom. The splines are disposed parallel to the longitudinal axis. The coupling chamber of the coupling has an inner surface with a plurality of complementary splines depending inwardly therefrom. The complementary splines are disposed parallel to the longitudinal axis, each of the complementary splines further disposed adjacent respective ones of the plurality of splines when the second end of the stub shaft is inserted in the coupling chamber of the coupling. In this aspect, the stub shaft, when engaged in the coupling chamber, is designed to fail prior to failure of a crankshaft of the engine. Similarly, the coupling engaged with the stub shaft will fail if necessary prior to failure of crankshaft of the engine. Moreover, a plurality of bushings disposed about the coupling engaged with the stub shaft will fail prior to failure of the stub shaft and the crankshaft, flywheel or other engine components. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further aspects and advantages of the invention will be apparent from the following description, or can be learned through practice of the invention, in combination with the drawings, which serve to explain the principles of the invention but by no means are intended to be exhaustive of all of possible manifestations of the invention. At least one embodiment of the invention is shown in the drawings in which: 
       FIG. 1  is a perspective side view of an embodiment of the present invention installed in an environment in which the invention is intended to be employed; 
       FIG. 2  is a front elevational view of a portion of a drive assembly taken along lines  2 — 2  in  FIG. 1 ; 
       FIG. 3  is a detailed view of a portion of the drive assembly as in  FIG. 2  with various components removed for clarity; 
       FIG. 4A  is a front elevational view a detailed view of the portion of the drive assembly as in  FIG. 3  with an engine sheave removed for further clarity; 
       FIG. 4B  is a partial cross section of a shaft assembly taken along lines  4 B— 4 B in  FIG. 4A ; and 
       FIG. 5  is an exploded perspective view of the shaft assembly as in  FIG. 4B  in relation to other components of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Detailed reference will now be made to the drawings in which examples embodying the present invention are shown. The detailed description uses numerical and letter designations to refer to features of the drawings. Like or similar designations of the drawings and description have been used to refer to like or similar parts of the invention. 
   The drawings and detailed description provide a full and written description of the invention, and of the manner and process of making and using it, so as to enable one skilled in the pertinent art to make and use it, as well as the best mode of carrying out the invention. However, the examples set forth in the drawings and detailed description are provided by way of explanation only and are not meant as limitations of the invention. The present invention thus includes any modifications and variations of the following examples as come within the scope of the appended claims and their equivalents. 
   The figures broadly embody a cutting machine, designated in general by the element number  10 . The cutting machine  10  generally includes a locomotion apparatus  12  for moving and maneuvering the cutting machine  10 , a power plant such as a gas or diesel engine  14 , and a cutting apparatus  16  such as a stump grinder or brush cutter to clear stumps, brush, and the like from an area of land. These and other components and characteristics of the cutting machine  10  are described in greater detail and by way of exemplary operation below. 
   With particular reference to  FIG. 1 , the engine  14  of the cutting machine  10  provides power to the locomotion apparatus  12  to drive the cutting machine  10 . As shown in this example, the locomotion apparatus  12  is a tracked system, which includes a plurality of wheels  12   a  and an endless tread or track  12   b  for rotation about the wheels  12   a  to maneuver the cutting machine  10  in various directions. Also shown, a control system  18  is provided to govern power transfer from the engine  14  to the cutting apparatus  16  such as by increasing rotation speed of components within a drive assembly  20 , as described below. 
   According to the embodiment shown in  FIG. 1 , the cutting apparatus  16  is a stump grinder system, which includes a cutting device  19  for grinding and removing stumps. It will be appreciated that the cutting apparatus  16  is not limited to this exemplary stump removal arrangement. The skilled artisan will instantly appreciate that the cutting apparatus  16  can also be a brush cutter or a chipper. Therefore, as used herein, the phrase “cutting apparatus” is used to mean brush cutter, brush chipper, stump grinder and the like. It will be further appreciated that the cutting device  19  can utilize a cutting or grinding wheel, a chainsaw, a plurality of cutting teeth or similar cutting arrangements. 
     FIG. 1  further introduces a stub shaft assembly  22 , which is shown in phantom under a protective belt guard or cover  24   a . A portion of the stub shaft assembly  22  projects through an inner guard or wall  24   b  of the drive assembly  20  from the engine  14  that, as will be described in further detail below, operably connects the engine  14  and the cutting apparatus  16 . In general, the stub shaft assembly  22  provides a failsafe mechanism to prevent damage to the engine  14 , more particularly, to an engine crankshaft  61  (see  FIG. 5 ), should the cutting device  19  become wedged on a workpiece such as a tree stump. In other words, the stub shaft assembly  22  and its components as described in detail below are designed to fail at a predetermined shear modulus before an overtorque situation leads to failure of components of the engine  14 . 
   With reference to  FIGS. 1 and 2 , the inner wall  24   b , one or more endless belts  26  such as V-belts, a jackshaft sheave assembly  28 , and an engine sheave assembly  30  are shown clearly with the belt guard  24   a  removed. As shown, the jackshaft sheave assembly  28  is connected to the cutting device  19 . The skilled artisan will instantly appreciate that a jackshaft may not be necessary in some direct drive cutting machines such as a chipper and is provided here only by way of example. 
   The jackshaft sheave assembly  28  includes a jackshaft sheave  28   a  with a plurality of annular races  28   b  (alternatively, run or groove) formed about the jackshaft sheave  28   a . The belts  26  rotate about the annular races  28   b  of the jackshaft sheave  28   a  in concert with an engine sheave  32  of an engine sheave assembly  30 . 
   More particularly, with reference now to  FIG. 3 , the engine sheave  32  includes a plurality of outer complementary annular races  32   a  formed about the engine sheave  32 . The engine sheave assembly  30  is connected to the engine  14  to receive power from the engine  14  as noted above. As the engine  14  powers the engine sheave  32 , the belts  26  rotate about the complementary annular races  32   a  of the engine sheave  32 , which also rotate about the annular races  28   b  of the jackshaft sheave  28   a  to power the cutting device  19 , also noted above. One skilled in the art will instantly recognize that a variety of endless belts, lines or chains made of metal, rubber or hardened plastic materials can be used for the belts  26  and further details are not necessary to appreciate and practice this aspect of the invention. 
     FIG. 3  further shows a bushing  34  in the engine sheave assembly  30 . As shown, the bushing  34  is located in a bushing aperture  32   b  of the engine sheave  32 . The bushing  34  includes a plurality of first holes  34   a  and a plurality of complementary bolts  34   b  to mount the engine sheave  32  and the bushing  34  together. A plurality of second holes  34   c  (alternatively, “push-off” or removal holes) is also provided in the bushing  34  to store respective bolts  34   b  temporarily when the engine sheave assembly  30  is being disassembled for maintenance. 
     FIG. 3  also shows an inner shaft aperture  34   d  in the bushing  34  for receipt of a stub shaft  42 . A key  34   e  projects from the bushing  34  into a channel  44   b  of the stub shaft  42  in this example to mate the bushing  34  and the stub shaft  42  together. The skilled artisan will instantly recognize that the key  34   e  and the channel  44   b  can be reversed on the bushing  34  and the stub shaft  42 , or additional keys and channels can be utilized to mate the bushing  34  and the stub shaft  42  together. Moreover, various combinations of keys and channels on each of the bushing  34  and the stub shaft  42  can be employed to ensure that the bushing  34  and the stub shaft  42  are aligned and secured together. 
   As further shown in  FIG. 3 , a first grease fitting  46  and a second grease fitting  54  are provided to lubricate various components of the stub shaft assembly  22 . As shown, the first grease fitting  46  extends from a first end  44  of the stub shaft  42  for insertion of grease or other suitable lubricant to lubricate a plurality of splines  50  within the stub shaft assembly  22  (see  FIG. 4B ). Similarly, the second grease fitting  54  is for insertion of grease or other suitable lubricant to lubricate a plurality of bearings  57  in the stub shaft assembly  22  (see  FIG. 4B ). Moreover, the second grease fitting  54  includes a grease fitting extension  56  for convenient access to the grease fitting  54  when the drive assembly  20  is assembled with the belt guard  24   a  in place as shown in  FIG. 1 . Those skilled in the art will appreciate and understand operation of the grease fittings  46 , 54  without requiring additional details of this aspect of the invention. 
   Turning now to  FIGS. 4A and 4B , the stub shaft plate assembly  22  is most clearly shown with the engine sheave assembly  30  and the grease fitting extension  56  removed. As shown, the stub shaft assembly  22  includes a shaft plate  36  with an external face  38  defining a number of attachment holes  38   a  and a complementary number of attachment bolts  38   b . The shaft plate  36  is attached to the engine  14  via the attachment holes  38   a  and the attachment bolts  38   b  (see also  FIG. 5 ). A plurality of service (“push-off” or removal holes) holes  38   c  are also shown defined about the shaft plate  36  for use with one or more of the attachment bolts  38   b  when the shaft plate  36  is being disassembled for service or repair. In use, some of the attachment bolts  38   b  are removed from their attachment holes  38   a  and inserted in the service holes  38   c  to temporarily hold a weight of the shaft plate  36  as the shaft assembly  22  is being disassembled. The skilled artisan will instantly appreciate that any attachment device or mechanism other than bolts can be used to attach the shaft plate  36  to the engine  14 . For instance, screws, cotter keys and the like may be used in lieu of or in addition to the bolts  38   b.    
   As further shown in  FIGS. 4A and 4B , the stub shaft  42  has a first distal end  44  defining a circumferential exterior surface  44   a  in which the channel  44   b  introduced above is formed. As shown, the stub shaft  42  extends from a shaft aperture  38   d  of a shaft housing  52 . The housing  52  defines an outer annular surface  52   a  and a shoulder  52   d . The second grease fitting  54  is located on the outer annular surface  52   a  of the shaft housing  52  to lubricate the bearings  57  as noted above. 
   With more particular reference to  FIG. 4B , the stub shaft  42  defines a longitudinal axis Z extending through the shaft plate  36  and from the shaft housing  52 . The shoulder  52   d  of the shaft housing  52  is spaced apart from the external face  38  of the shaft plate  36 , which defines a predetermined depth D 1  of the shoulder  52   d  relative to the shaft plate  36 . The depth D 1  of the shoulder  52   d  and a predetermined length L of the stub shaft  42  position the engine sheave  32  at a desired distance from the external face  38  of the shaft plate  36  in order to accommodate components such as the grease fitting  54  and the grease fitting extension  56 . 
   Also shown in  FIG. 4B , the exemplary shaft housing  52  includes a fixed run  52   a , an inner chamber  52   b , and a race  52   c . The bearings  57  rotate between the fixed run  52   a  and the race  52   c  within the inner chamber  52   b  as a middle exterior surface  44   b  of the stub shaft  42  rotates. As noted above, the second grease fitting  54  provides grease (not shown) to lubricate the bearings  57  as they rotate in the fixed run  52   a  and the race  52   c . Those skilled in the art will understand that this arrangement of the fixed run  52   a , the race  52   c  and the ball-shaped bearings  57  are provided by way of example only and any suitable race-bearing arrangement including tapered roller bearings can be used in lieu of or in addition to those shown and described. 
     FIG. 4B  further shows a second end  48  of the stub shaft  42 , which defines a circumferential outer surface  48   a  having a plurality of splines  50  radially extending from the outer surface  48   a . As shown, the splines  50  extend parallel to the longitudinal axis Z of the stub shaft  42  and are inserted into a coupling  60  positioned within the coupling plate  58 . 
   More particularly, with reference to  FIGS. 4B and 5 , the stub shaft assembly  22 , the coupling plate  58 , the coupling  60 , and an engine flywheel  62  are shown respectively assembled and in a comparative exploded relationship. As shown, the shaft plate  36  of the stub shaft assembly  22  has an internal face  40  opposing its external face  38 . In this example, the internal face  40  is depressed or cupped inward such that the shaft plate  36  exhibits a concave shape for receiving the coupling  60 . 
   Also shown in  FIGS. 4B and 5 , the coupling plate  58  includes a first cutter side  58   a  and an opposing second flywheel side  58   b . The coupling plate  58  further includes a plurality of coupling holes  58   c  with respective coupling bolts  58   d  to attach the coupling plate  58  to the engine flywheel  62 . As noted above, any suitable attachment device or mechanism in lieu of or in addition to bolts can be used by the skilled artisan to couple the coupling plate  58  to the engine flywheel  62 . 
     FIG. 5  most clearly shows a coupling aperture  58   e  through which the coupling  60  is inserted. A plurality of grommets or rubber bushings  64  is disposed about the coupling  60  and through the coupling plate  58  to provide absorb shock. A first reinforcement collar  68  according to this aspect of the invention is interposed between the grommets  64  and the coupling plate  58  to reinforce the area of the coupling plate  58  about the coupling  60 . As shown, the grommets  64  extend through the coupling plate  58  and the first reinforcement collar  68  continuing through the second flywheel side  58   b  as well as a second reinforcement collar  70  in this aspect of the invention. A plurality of complementary bolts  66  secure the grommets  64  to the various components. 
   As further shown in  FIG. 5 , the coupling  60  includes a shaft end  72  defining an annular surface  74  that when assembled with the shaft plate  36  is located within the internal face  40  of the shaft plate  36 . Also defined in the shaft end  72  of the coupling  60  is a coupling chamber  76 , which includes an inner annular surface  76   a  with a plurality of teeth or complementary splines  76   b . The complementary splines  76   b  are complementary to the splines  50  introduced above to achieve a sliding fit as shown in  FIG. 4B . 
     FIGS. 4B and 5  further show a pilot end  78  of the coupling  60 , which extends from the second reinforcement collar  70  at a depth D 2 . The depth D 2  is sufficiently deep to extend past the bolts  66  in order for second end  48  of the stub shaft  42  to interact with the engine crankshaft  61 . More particularly, the engine flywheel  62  is arranged in the engine  14 , and the engine crankshaft  61  extends from the engine  14  for connection to the engine flywheel  62  in a known manner. 
   The engine flywheel  62  as shown in  FIGS. 4B and 5  includes a plate-flywheel interface  80  having a predefined depth D 3  that is complementary to the depth D 2  of pilot end  78  of the coupling  60 . As shown, the coupling plate  58  is attached to the flywheel  62  via the coupling bolts  58   d  and coupling plate attachment holes  82  in the flywheel  62 . Due to the interaction of the pilot end  78  with the plate-flywheel interface  80 , any shear or torquing forces are transmitted through the pilot end  78  of the coupling  60  rather than the coupling plate  58 , which as shown in this example is a thin metal plate to reduce weight and manufacturing costs and to ease assembly. 
   As best shown in  FIG. 5 , the rubber grommets  64  extend through the coupling plate  58  in a manner that should one or more of the rubber grommets  64  fail, the stub shaft assembly  22  will generate noise and vibration indicating to a user that repair is needed. Should the noise and vibration of the failed grommets  64  go unheeded, the coupling plate  58  will fail due to a predetermined shear modulus of its thin metal construction. Finally, the splines  50  and/or the complementary splines  76   b  of the coupling  60  will fail before damage occurs to the engine crankshaft  61  or other internal engine components (not shown). In other words, one or more of the above components external to the engine  14  will fail before the engine crankshaft  61  reaches its failure limit. Thus, costly damage to components of the engine  14  is avoided according to this exemplary aspect of the invention. 
   The invention may be better understood with reference the figures and to an operation and servicing of the cutting machine  10 . 
   Should the bearing supported stub shaft assembly  22  fail or require routine servicing, or if failure is suspected due to excessive noise and vibration during operation of the cutting machine  10 , the engine  14  and the control system  18  are powered off and secured to prevent inadvertent operation of the cutting system  16  and it cutting device  19 . Preferably, a battery supply (not shown) is also be disconnected from the engine  14 . Also, preferably, all components are allowed to cool prior to servicing to avoid burning the user. 
   According to a method of the invention, the stub shaft assembly  22  can be serviced by first removing the belt guard  24   a  as shown in  FIG. 1 . Next, the belts  26  (if more than one) are removed from the jackshaft sheave  28   a  and the engine sheave  32  (see  FIG. 2 ). The engine sheave assembly  30  is disassembled by removing the engine sheave  32  from the bushing  34 . The bushing  34  is removed from the belt drive assembly  20  by removing the bolts  34   b  from their respective holes  34   a  as shown in  FIG. 2 . Preferably, the bolts  34   b  are removed and temporarily stored in the holes  34   c  in the bushing  34  to avoid losing the bolts  34   b  during servicing. More particularly, the bolts  34   b  are screwed into the holes  34   c  to push the bushing  34  apart from the stub shaft assembly  22 . The holes  34   a ,  34   c  and the bolts  34   b  have complementary helical threads that facilitate screwing the bolts  34   b  out of the holes  34   a  and into the holes  34   c  in a known manner. As shown in  FIG. 2 , the bushing  34  has a channel  34   e  that fits or slides over the key  44   b  of the stub shaft  42 . Therefore, the bushing  34  is slid from the key  34   e  and away from the stub shaft  42  in a direction away from the belt drive assembly  20 . Finally, the inner guard wall  24   b  is removed by removing bolts or the like. 
   With respect to  FIG. 3 , the grease fitting extension  56  is removed from the second grease fitting  54  located on the outer annular surface  52   a  of the shaft housing  52 . The bearing supported stub shaft plate  36  is next removed. Specifically, the attachment bolts  38   b  are removed from the attachment holes  38   a  and at least one of the attachment bolts  38   b  attached in one of the service holes  38   c . As shown for example in  FIG. 4A , there are twelve 10 mm bolts to remove. Also in this example, at least two of the bolts  38   b  can be inserted into at least two of the services holes  38   c  and rotated to push the stub shaft plate  36  apart from the flywheel  62 . 
   More specifically, the two bolts  38   b  are screwed into the service holes  38   c  until the shaft plate  36  breaks free from about the coupling plate  58 . By leaving at least two of the attachment bolts  38   b  screwed at least slightly in the service holes  38   c , the bolts  38   b  can assist in preventing the shaft plate  36  from dropping when separated from the engine  14 . When ready to remove the shaft plate  36 , the bolts  38   b  can be completely removed from the service holes  38   c  while holding the first end  44  of the stub shaft  42  as shown in  FIG. 5  and sliding the shaft plate  36  away from the coupling plate  58 . 
   With reference to  FIGS. 4B and 5 , the coupling plate  58  can be removed by loosening and removing its eight coupling bolts  58   d  in this example. Once the coupling bolts  58   d  have been removed from their respective coupling holes  58   c , the coupling plate  58  can be removed from the flywheel  62 . After all components have been removed as above and the flywheel  62  is exposed, the flywheel  62  can be cleaned with any suitable cleaning solvent and checked for burrs or other damage around the plate flywheel interface  80  as well as around its coupling plate attachment holes  82 . 
   If burrs or other minor damage are discovered, very fine sandpaper can be used to remove such burrs. If the damage has occurred to the bushings  64  or to the coupling plate  58 , then the grommets  64  can be removed by removing the holding bolts  66  and/or the entire coupling plate  58  can be replaced. If the damage is discovered too late, the stub shaft  42  may also have realized damage to the splines  50  and may require replacing. In one aspect of the invention, the stub shaft  42  may be made of a more brittle or fragile metal such as brass to allow the stub shaft  42  to fracture at a predetermined shear modulus prior to damage occurring to the engine  14  such as its crankshaft  61 . If the damage is determined to be beyond repair, then non-engine parts of the invention can be replaced quickly and conveniently at relatively lower cost than those of the engine  14 . 
   The steps described above are simply reversed to reassemble the component parts of the stub shaft assembly  22 . It has been found that some type of locking fluid such as Loc Tight® 242 brand should be placed on the bolts and all bolts lightly tightened to reassemble the components. Specifically, all bolts should be torqued to about 35 ft.-lbs. Further, an anti-seize coupling lubricant can be inserted in the coupling chamber  76  of the coupling  60 . Also, care should be taken to line up the splines  50  with the complementary splines  76   b  before sliding the stub shaft  42  into the coupling chamber  76  to prevent any damage to the splines  50 , 76   b . Additionally, the grease fitting  54  should be placed substantially in the twelve o&#39;clock position as shown in  FIGS. 4A and 4B  to ensure that the extension  56  can be reattached to the grease fitting  54 . Before starting the engine  14 , grease or other appropriate lubricant should be applied to the grease fittings  46 , 54  in a known manner. As shown in  FIG. 4B , a grease relief fitting  55  is provided to release excess grease to prevent over-pressurizing the chamber  52   b.    
   Although the invention has been described in such a way as to provide an enabling disclosure for one skilled in the art to make and use the invention, it should be understood that the descriptive examples of the invention are not intended to limit the present invention to use only as shown in the Figures. For instance, an outer perimeter of the shaft plate  36  can be square, rectangular, oblong and various other shapes other than the illustrated round shape. Likewise, specific shapes of other components can be altered to suit particular applications. Additionally, positions of certain components can be reversed or alternated, such the key  34   e  of the bushing  34  and the channel  44   b  of the stub shaft  42  as previously noted. It is intended to claim all such changes and modifications as fall within the scope of the appended claims and their equivalents. Thus, while exemplary embodiments of the invention have been shown and described, those skilled in the art will recognize that changes and modifications may be made to the foregoing examples without departing from the scope and spirit of the invention.