Abstract:
Apparatus and methods for removing a gear from a shaft. In one embodiment, the invention includes a slotted gear puller which engages the web of a gear and can be used to pull the gear from the shaft based on engagement of the gear puller with the gear in the area of the web of the gear.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   The present invention claims the benefit of priority to U.S. Provisional Patent Application Ser. No. 60/503,690, filed Sep. 17, 2003, which is incorporated herein by reference. 

   FIELD OF THE INVENTION 
   The present invention relates to methods and apparatus for removing a component that is attached to another component, and in particular for removing a press-fit gear from a shaft. 
   BACKGROUND OF THE INVENTION 
   Service technicians needed a fast, effective, method for pulling a press fit gear from a shaft without having to partially, or fully remove the shaft. Some removal methods and apparatus require that the shaft be partially removed (for example, slid forward one journal) in order to remove the gear. Although the gear removal apparatus and methods described in this document were developed for removal of a camshaft gear from a diesel engine, the features of various embodiments of the invention described herein are potentially applicable to any press fit component, especially those components including one or more surface features suitable for use with the types of component clamping described herein and their equivalents. 
   SUMMARY OF THE INVENTION 
   An apparatus for removing a gear, the apparatus includes an attachment member which rotates in order to slide into a fitting relationship with the web of a gear. The apparatus also includes a pilot member for reacting the loads of the lugs of the attachment member when the gear in being pulled. 
   In yet another aspect of some embodiments of the present invention pertains to an attachment member which includes a plurality of fingers which can be inserted through and rotated behind corresponding apertures in the web of the gear. There is also a plurality of sliding pins which assist in coupling the attachment member to the gear web. 
   Another aspect of some embodiments of the present invention relate to a method for removing a gear from a shaft. The method includes inserting a plurality of lugs through the apertures of the gear, rotating the lugs in unison so that they are in contact with the gear web, and pulling the gear web by the lugs to remove the gear from the shaft. 
   These and other aspects of the present invention will be apparent from the drawings, claims, and text to follow. 

   
     DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a top and side perspective view of a gear puller assembly according to one embodiment of the present invention. 
       FIG. 2  is a bottom plan view of a gear coupling member according to one embodiment of the present invention. 
       FIG. 3  is a view of the apparatus of  FIG. 2  as taken along the line  3 - 3  of  FIG. 2 . 
       FIG. 4  is a view of the apparatus of  FIG. 3  as taken along the line  4 - 4  of  FIG. 3 . 
       FIG. 5  is a side and front exploded perspective view of a gear pulling assembly according to one embodiment of the present invention prior to attachment to a gear. 
       FIG. 6  is a front perspective view of an engine having a gear to be pulled. 
       FIG. 7  is a view of the assembly of  FIG. 6  including a gear pulling assembly according to one embodiment of the present invention. 
       FIG. 8  is a view of the apparatus of  FIG. 7  installed on a gear of an engine. 
       FIG. 9  is a side elevational view a gear pulling assembly according to another embodiment of the present invention. 
       FIG. 10  is a view of the apparatus of  FIG. 9  as viewed along line  10 - 10  of  FIG. 9 . 
       FIG. 11  is a view of the apparatus of  FIG. 10  as viewed along line  11 - 11  of  FIG. 10 . 
   

   DESCRIPTION OF PREFERRED EMBODIMENT 
   For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated devices, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates. 
   All drawings shown herein are scaled drawings. Further, some of the drawings include dimensions (in centimeters), as well as tolerancing information. It is understood that these specific dimensions and tolerances are one embodiment of the present invention, and the invention contemplates apparatus of different sizes and shapes. 
   Referring to  FIG. 1 , a gear removal assembly  20  is shown in perspective view. Assembly  20  includes a generally cylindrical gear attachment member  22 . Gear attachment member  22  comprises a cylindrical faceplate  24  with three, finger-shaped, gear mounting lugs  28   a,    28   b,  and  28   c  extending from one side of the faceplate. A pair of spring loaded plungers  26  are shown threadably engaged into faceplate  24 . Although two plunger assemblies  26  are shown and described, it is understood that the present invention contemplates a single plunger, and also contemplates as many plungers as there are lugs. 
   Referring to  FIGS. 2-4 , various orthogonal views of a gear attachment member according to one embodiment of the present invention are shown.  FIG. 2  shows a bottom plan view of member  22 . Threaded holes  36   a  and  36   b  extend through the thickness of faceplate  24 . Mounting lugs  28   a,    28   b,  and  28   c  are equally spaced around an annular bottom-side face of faceplate  24 . Even though equal spacing of the mounting lugs has been shown and described, the present invention contemplates lugs arranged in any spacing. Preferably, the lugs are spaced corresponding to the apertures or lightening holes in the web of the gear to be pulled. Since in many gears the lightening holes are equally spaced, in some embodiments of the present invention the lugs are evenly spaced. 
   Referring to  FIG. 3 , a side view of member  22  is shown. As best seen in  FIGS. 1 ,  3 , and  5 , each mounting lug  28  includes a corresponding slot  30  defined between the back face of faceplate  24  and a corresponding clamping face  32  of the lug. For instance, mounting lug  28   b  includes a slot  30   b  defined between the back face of faceplate  24  and an opposing, clamping face  32   b.  As best seen in  FIG. 1  with respect to mounting lug  28   a,  each lug is preferably unitary with faceplate  24 , with a transition section  31  a extending from the bottom face of faceplate  24 , transition section  31  being integral with clamping face  32 . As best seen in  FIGS. 1 and 3 , each attachment lug  28  may also include a raised step face  33  that extends upward slightly from the back face faceplate  24 . Slots  30   a,    30   b,  and  30   c  are adapted and configured to mate with corresponding features of the component being removed. In a preferred embodiment, gear attachment member  22  is a single, unitary piece which can be fabricated as a casting, or as multiple pieces which are then fastening together, adhered together, or welded or brazed together. By fabricated attachment member  22  into a single piece, it is easier to maintain close tolerances in the shape of the lugs and slots so as to minimize any damage to the gear web. 
   Referring to  FIG. 4 , a front plan view of faceplate  24  is shown. A plurality of threaded attachment holes  34   a,    34   b,  and  34   c  extend from the front side of faceplate  24  through the faceplate to the bottom side of faceplate  24 . As best seen in comparing  FIGS. 2 ,  3 , and  4 , it is seen that threaded hole  34   a  breaks into the one side of mounting lug  31   a  (i.e., threaded hole  34   a  breaks into slot  30   a ). Threaded holes  34   a,    34   b,  and  34   c  are spaced around the annular volume of faceplate  24 , and are registered with the corresponding slots  30   a,    30   b,  and  30   c,  respectively. 
   Referring to  FIG. 5 , there is shown a gear pulling assembly  60  according to one embodiment of the present invention. Assembly  60  preferably includes gear removal assembly  20 . Assembly  60  further includes threaded studs  30   a,    30   b,  and  30   c  which are threadably coupled to the corresponding hole  36   a,    36   b,  and  36   c,  respectively, of member  22 . Each stud  38  is preferably threaded on each end. Further, the intermediate section between threaded portions preferably includes an outer surface adapted and configured for interfacing with a common tool, such as a hex-shaped outer surface. In some embodiments, each stud includes a first shoulder  39   a,    39   b,  or  39   c,  respectively, which provides stand-off support for the screw member  66 . These shoulders are spaced along the length of the corresponding stud so as to establish a minimum position between attachment member  22  to allow sufficient access and visibility to pilot  62 . 
   Assembly  60  further includes a replacer screw member  66 , which in one embodiment has a triangular shape. Further, replacer screw member  66  includes smooth-bore through-holes  67   a,    67   b,  and  67   c  which are sized to receive therethrough a threaded end of the corresponding stud  38 . Member  66  preferably includes a threaded through-hole  65  which threadably receives a fastener  64 . A pilot member  62  is threadably coupled to the end of fastener  64 . It will be appreciated that in some embodiments of the present invention it is not necessary to include studs and a screw member  66  which are threadably attachable to attachment member  22 . In these embodiments, pilot member  62  is threadably coupled to one or more integral features of the gear attachment member. 
   From  FIG. 5 , which is shown in exploded view, it can be appreciated that replacer screw member  66  is slidingly received on one end of the studs  38 . A fastener  67   a,    67   b,  or  67   c,  (such as a nut) is fastened onto a threaded end of the corresponding shaft  38   a,    38   b,  or  38   c,  respectively. With nuts  65   a,    65   b,  and  65   c  coupled to the corresponding end of the stud  38   a,    38   b,  or  38   c,  respectively, member  66  is constrained from being removed from the studs, but is able to slidingly move toward attachment member  22 . 
   As best seen in  FIGS. 1 and 5 , assembly  20  preferably includes at least one spring-loaded plunger  26 . Referring to  FIG. 5 , as one example, each spring-loaded plunger  26  includes a threaded body portion  26 . 1 , an “L”-shaped plunger  26 . 2 , and an internal spring (not shown) which urges plunger  26 . 2  toward member  22  (as best seen in  FIG. 5 ). Each plunger body  26 . 1  is threaded and received within a corresponding hole  36   a  or  36   b  (as best seen in  FIG. 2 ). Referring again to  FIG. 5 , body  26 . 1  further includes a hex-shaped end suitable for wrenching. In a preferred embodiment, each plunger  26  is spaced apart from the closed end of the slot of an adjacent lug by a distance X (see  FIG. 1 ). This spacing X is chosen to be a distance that is less than the width of the gear aperture through which the adjacent lug is being positioned. 
     FIGS. 6 ,  7 , and  8  each show various stages in which apparatus and methods according to one embodiment of the present invention are employed.  FIGS. 6-8  each include an engine  50 , such as a diesel engine. Engine  50  includes one or more gears  52  which are press-fit onto one end of a shaft  56 . In one embodiment, gear  52  is a camshaft gear, and shaft  56  is the camshaft for engine  50 . Gear  52  further includes one or more features  54  which are adapted and configured for coupling with mounting lugs  28 . For example, camshaft gear  52  includes lightning holes  54   a,    54   b,  and  54   c.  These lightning holes  54  are shown equally spaced about the web of gear  52 . Although a plurality of equally-spaced lightning holes have been shown and described, the present invention contemplates mounting lugs  28  which interface with other types of component features, (for example, holes of any spacing). 
   What follows now is a description of a method according to one embodiment of the present invention for removing a component press-fit onto another component. 
   Referring to  FIG. 5 , install the studs  38  into the member  22 . Hand tighten the studs. Install the replacer screw member  66  on the studs  38 . Install the nuts  65  onto the studs  38  and hand tighten. Install the spring plungers  26 , if required. 
   Referring to  FIG. 6 , loosen the thrust plate capscrews approximate two turns. Rotate the camshaft gear until the keyway is located at the 1-o&#39;clock position. Place the shaft pilot  62  on the end of the shaft  56 . Install the socket head capscrew  64  and hand tighten. 
   Referring to  FIG. 7 , install the assembly  60  onto the gear  52 . Rotate clockwise until the lugs  28  of member  22  are fully engaged in the corresponding gear feature  54 . 
   Referring to  FIG. 8 , install the handle  68  in the replacer assembly  60 . Using a wrench, turn the fastener  64  clockwise while holding the handle  68  to prevent gear rotation and remove the gear  52 . 
   The 3-lugs  28  on the member  22  are inserted in the clamping features  54  of the gear  52 , and then rotated into position behind the gear  52 . Installation of the tool is accomplished from the front side of the gear and does not require partially or fully removing the shaft. The preferably large size of the lugs also provides for a positive engagement of the member  22 . This member  22  resists slipping off the gear. Some embodiments of the invention include a spring-loaded pin  26  that locks the member  22  to the gear  52  and insures that the lugs  28  are correctly positioned behind the gear  52 . 
   In these embodiments, plunger  26  is biased toward the gear to be pulled and biased away from the pilot. As the attachment member is brought into proximity with the web of the gear, and when the lugs  28  are positioned in the corresponding apertures, the plungers  26  are forced toward the pilot. This extension of the plunger away from the gear provides full indication that the lugs  28  are positioned in and through the corresponding gear aperture. In those embodiments in which the circumferential or angular extent  40  of the lug (see  FIG. 2 ) is about the same as the circumferential or angular extent of the corresponding gear aperture, the end  26 . 3  of the plunger (see  FIG. 1 ) rides upon the face of the gear web. However, when attachment member  22  is subsequently rotated so that the corresponding portions of the gear web are located within the corresponding slots of the lugs, plunger end  26 . 3  will no longer be supported by the web face, and the biasing spring of the plunger will cause the plunger end  26 . 3  to extend through the web aperture. In these embodiments, this dropping through of the plunger end  26 . 3  into and through the web aperture provides a visual and audible indication that the attachment member  22  has been properly rotating into place, such that the corresponding lugs are positioned to pull the gear from the shaft. Further, since in some embodiments there is a biasing spring which maintains the pin in this extending position, it will not be possible to rotate the attachment member out of position without pulling back on each plunger to allow the attachment member  22  to rotate in the opposite direction in order to be removed from the gear. 
     FIGS. 9 ,  10  and  11  depict various orthogonal views of a gear removal assembly  120  according to another embodiment of the present invention. The use of a one hundred prefix (1xx) before an element number (xx) denotes an element that is the same as the non-prefixed element number (xx), except for the differences shown and described. 
   As best seen in  FIG. 10 , the concentric-circles indicate the outer diameter for different assemblies  120  each sized to pull different sizes of components. 
   While the invention has been illustrated and described in detail in the foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been described and that all changes and modifications that come within the spirit of the invention are desired to be protected.