Patent Publication Number: US-6212775-B1

Title: Method and apparatus for pulling bushings and bearings

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a new and improved method and apparatus for pulling bushings or bearings. More specifically the present invention provides a method and apparatus for pulling bushings or bearings quickly and easily from a hole wherein the bushing or bearing is tightly positioned within the hole and requires special tools and/or methods for removing the bushing or bearing from the hole, particularly when the bushing or bearing is situated in a blind hole. For reference purposes, the term bushing will be used synonymously with the term bearing since the method and apparatus of the present invention applies to the removal of both bushings and bearings similarly situated. 
     2. Description of the Prior Art 
     Various types of bushings and bearings can be frequently mounted in situations where the bushing can only be accessed from one side, this is commonly known as a blind hole. Often times, as in the case of a standard bushing used for a tree spade, there is no space left behind the bushing in order to leverage a damaged bushing from the hole. Furthermore, conventional type bushing pullers, even blind hole bushing pullers cannot pull bushing from a blind hole if there is no gap present behind the bushing, or if there is no bushing mount so as to grab the bushing with standard type bushing pullers. 
     The conventional method of removing a bushing that is press fit into a blind hole would be to cut off the back end or grease cap of the blind hole with a torch. After the back end of the blind hole is cut off, then the damaged bushing is then carefully cut lengthwise with a torch, while at the same time being careful so as to not damage the bushing boss supporting the bushing. The damaged bushing can then be forced out from the back end with a tool and/or a hammer. After the bushing is removed, the lining within the bushing boss would need to be inspected for damage and properly cleaned before a new bushing can be inserted. Furthermore, the grease cap or the back end of the blind hole would need to be welded back on and a new bushing can then be inserted. 
     The entire procedure of removing the damaged bushing using this conventional method can take approximately 30 minutes to an hour for each damaged bushing. This can place a machine that uses multiple bushings out of service for a few days. We have therefore provided a bushing removal tool and method that can remove damaged bushings quickly and easily in about five minutes without a concern of causing any other damage to the bushing boss supporting the bushing. 
     There have been various types of bushing and bearing pullers available in the marketplace, but none have gained widespread acceptance because of their difficulty of use and the inability for quickly and easily removing bushing or bearings, particularly from a blind hole. In addition, other types of bushing pullers require additional time to remove the bushing/bearing, do not provide flexibility and ease of use of our puller and do not employ the particular method that we have developed in removing bushings and bearings from a bushing boss or a hole, especially when the bushing/bearing is situated in a blind hole. 
     These and other types of pullers used in the past do not offer the flexibility and inventive features of our method and apparatus for pulling bushings and bearings. As will be described in greater detail hereinafter, the method and apparatus of the present invention differs from those previously proposed. 
     SUMMARY OF THE INVENTION 
     According to our present invention we have provided a blind hole bushing puller comprising a drawing portion comprising: a rectangular cross block having a first end-portion and a second end portion and a pair of elongated leg screws a securement portion comprising, a circular bushing insert, and a connection portion comprising a bolt with a matching washer and a nut. Each of the end-portions of the cross block have a threaded leg hole formed therethrough, the cross block also has a centrally located unthreaded cross block hole. One of the leg screws passes through one of the threaded leg holes, and the other leg screw passes through the other threaded leg hole. The bushing insert has a centrally located unthreaded bushing insert hole and is sized to snugly fit about an inside diameter of the bushing. The bolt is sized to pass through the bushing insert hole and the cross block hole with a head of the bolt being positioned adjacent an upper portion of the bushing insert. The bolt head is sized slightly larger than the bushing insert hole and has a sufficient length so as to allow a lower portion of the bolt to extend beyond a lower end of the cross block hole. The bolt is securable to the cross block by the washer and the nut. Whereby when the bushing insert is securely attached within the bushing and the bolt is secured through the bushing insert and the cross block, the leg screws can be tightened in a direction wherein an upper portion of the leg screws comes into engagement with a housing portion supporting the bushing. The leg screws can then be further tightened in an alternating fashion thereby pulling and eventually removing the bushing from the hole. 
     We have further provided a blind hole bushing puller as described above, wherein each of the leg screws has a hexagonal head at a lower end thereof, wherein the leg screws can be tightened by engaging the hexagonal heads. 
     Still another feature of our invention concerns the blind hole bushing puller as described above, wherein each of the leg screws has a leg end pivotally positioned at an upper end thereof, the leg ends having a flat upper surface for engagement with a housing portion supporting a bushing that is to be removed. 
     Still yet another feature of our invention concerns the blind hole bushing puller as described above, wherein the bushing insert includes a key stock securely attached at an upper surface thereof, the key stock being positioned on the bushing insert in such a location so as to prohibit the bolt head from turning when the bolt has been inserted all the way through the bushing insert, thereby allowing a user to securely tighten the bolt to the cross block. 
     Yet another feature of our invention concerns the blind hole bushing puller as described above, wherein the distance between the pair of elongated leg screws is adjustable so as to provide for the removal of various sized bushings. 
     A still further feature of our invention concerns the method for pulling a bushing from a blind hole comprising the steps of: a) providing a bushing puller of the type described above; b) placing the bolt through the bushing insert hole of the bushing insert; c) securely attaching the bushing insert within the bushing with the bolt head being positioned within the bushing and a lower portion of the bolt extending outside of the bushing; d) attaching the cross block to the lower portion of the bolt by passing the lower portion of the bolt through the centrally located unthreaded hole in the cross block and securing the cross block to the bolt by placing the washer and the nut onto the bolt; e) tightening the leg screws in a direction wherein an upper portion of the leg screws comes into engagement with a housing portion supporting the bushing; and f) further tighten the leg screws in an alternating fashion to pull and remove the bushing from the blind hole. 
     An even further feature of our invention concerns the method described above, wherein the bushing insert is securely attached within the bushing by welding the bushing insert to the bushing. 
     Other objects, features and advantages of our invention will become more readily apparent upon reference to the following description when taken in conjunction with the accompanying drawings, which drawings illustrate several embodiments of my invention. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded perspective view of our bushing puller embodying important features of our invention; 
     FIG. 2 is a cross-sectional side view of our bushing puller prepared to pull a bushing from a bushing boss or a hole; 
     FIG. 3 is a top plan view of the bushing puller insert used in our invention; 
     FIG. 4 is a side view of our bushing puller insert shown in FIG. 3; 
     FIG. 5 is a partial cross-sectional side view illustrating the positioning of our bushing puller insert within a bushing that is to be pulled from a hole; 
     FIG. 6 is a cross-sectional side view illustrating our method of pulling a bushing from a hole using our bushing puller; 
     FIG. 7 is a cross-sectional side view further illustrating our method of pulling a bushing from a hole using our bushing puller; 
     FIG. 8 is a cross-sectional side view illustrating how a bushing is finally removed from a hole using our bushing puller and method; 
     FIG. 9 is an exploded perspective view of another embodiment of our bushing puller illustrating further important features of our invention wherein our bushing puller is adjustable for pulling bushings of varying sizes; and 
     FIG. 10 is a side view of our bushing puller shown in FIG.  9 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, FIGS. 1 and 2 show our bushing/bearing puller  10  used for pulling a bushing  11  and/or a bearing from a blind hole  12 . Our bushing puller  10  comprising: a rectangular cross block  14  having a first end-portion  16  and a second end portion  18 , a pair of elongated leg screws  20 ,  22 , a circular bushing insert  24 , and a bolt  26  with a matching washer  28  and a nut  30 . 
     Each of the end-portions  16 ,  18  of the cross block  14  have a threaded leg hole  32 ,  34  formed therethrough, and a centrally located unthreaded cross block hole  36  all of which are aligned along a longitudinal axis  100 . The cross block  14  can be made of steel, aluminum or any other type of material durable and strong enough to perform the function of pulling a bushing tightly secured within a blind hole. 
     Each of the leg screws  20 ,  22  passes through and is threadingly engaged with one of the threaded leg holes  32 ,  34 . The bushing insert  24  has a centrally located unthreaded bushing insert hole  38  and is sized to fit snugly about an inside diameter of the bushing  11 . The bolt  26  is sized to pass through the bushing insert hole  38  and the cross block hole  36  with a head  40  of the bolt being positioned adjacent an upper portion of the bushing insert  24 . 
     The bolt head  40  is sized slightly larger than the bushing insert hole  38  and has a sufficient length so as to allow a lower portion of the bolt  26  to extend beyond a lower end of the cross block hole  36 . The bolt  26  is securable to the cross block  14  by the washer  28  and the nut  30 . When the bushing insert  24  is securely attached within the bushing  11  and the bolt  26  is secured through the bushing insert  24  and the cross block  14 , the leg screws  20 ,  22  can be tightened in a direction wherein an upper portion of the leg screws comes into engagement with a housing portion  42  supporting the bushing  11 . The leg screws  20 ,  22  can then be further tightened in an alternating fashion thereby pulling and eventually removing the bushing  11  from the hole  12 . 
     In order to pull a 2½ inch bushing from a blind hole, excellent results can be obtained when: the cross block  14  is made of steel being one inch thick, two inches wide and six inches long, the threaded leg holes have a {fraction (9/16)} inch diameter with a ⅝ inch thread (18 threads per inch), and the unthreaded cross block hole has a {fraction (9/16)} inch diameter; and the bushing insert  24  is ½ inch thick with a {fraction (9/16)} inch center hole, and the diameter is sized to be approximately 0.002 inches less than the inner diameter of the bushing, with a tolerance of +/−0.001 inches. 
     In order to make it easy to tighten the leg screws  20 ,  22  with a high impact wrench  44  or a standard wrench, we have provided hexagonal heads  46 ,  48  on the ends of the leg screws. We have also provided leg ends  50 ,  52  that are pivotally positioned at an upper end of the leg screws  20 ,  22 . The leg ends  50 ,  52  are designed to have a flat upper surface for engagement with the housing portion  42  supporting the bushing  11  that is to be removed from the blind hole  12 . 
     In order to tightly secure the bolt  26  through the bushing insert  24  and the cross block  14 , we have alternatively added key stock  54  (FIGS. 3-5) that is securely attached at an upper surface of the bushing insert  24 . The key stock  54  can be secured in place with a weld  56 . The key stock  54  is positioned on the bushing insert  24  in such a way so as to prohibit the bolt head  40  from turning when the bolt  26  has been inserted all the way through the bushing insert  24 , thereby allowing a user to securely tighten the bolt  26  to the cross block  14 , thereby keeping the bolt from unnecessarily rotating as one is trying to tighten the bolt  26  down. 
     FIGS. 6-8 illustrate our method of using our bushing puller  10  for pulling a worn bushing  11  from a socket or a blind hole  12  on a tree spade. First a threaded bolt  26  is extended through the bushing insert  24 . Then the bushing insert  24  is welded  58  to the bushing insert. A bushing removal tool  10  is then secured to the bolt. Alternative forces are then applied, first to the tree spade  42  at one side of the worn bushing  11  and then another force to a second and opposite side of the worn bushing  11 . This process of applying alternating forces is repeated to rock the cross block  14  about a first transverse axis  102  that is perpendicular to the longitudinal axis  100  and simultaneously translate the cross block  14  linearly along a second transverse axis  104  that is mutually perpendicular with the longitudinal axis  100  and first transverse axis  102  until the worn bushing  11  is displaced from the tree spade socket  12 . A new bushing can then be inserted into the tree spade socket to complete the reconditioning of the tree spade. 
     More specifically, FIGS. 6-8 illustrate how the bushing  11  is walked out when the leg screws  20 ,  22  are tightened in an alternating fashion to pull and remove the bushing  11  from the blind hole  12 . FIG. 6 shows how the bushing  11  is slightly pulled from the blind hole  12  and the cross block  14  is slightly angled in relationship to the housing  42  supporting the bushing  11  as the leg screw  20  is tightened. FIG. 7 shows the next step how the bushing  11  is pulled even more from the blind hole  12 , and the cross block  14  is now slightly angled the other way in relationship to the housing  42  as the leg screw  22  is tightened. FIG. 8 finally shows how the bushing  11  is finally removed from the blind hole  12  as the leg screws  20 ,  22  have been tightened in a continuous alternating fashion so as to “walk out” the bushing  11  from the blind hole  12 . 
     Excellent results can be obtained when the bushing insert  24  is securely attached within the bushing  11  by welding  58  the bushing insert  24  directly to the bushing  11 . It is generally common for facilities or businesses that perform repairs on equipment that requires a replacement of press fit bushings to have a welding gun readily available for use. 
     We have also provided a modified version of our bushing puller in order to accommodate the removal of bushings of various sizes. As can be seen in FIGS. 9 and 10, this bushing puller  60  has adjustable leg hole inserts  62 ,  64  that are sized to engage a widened ridged hole  66 ,  68  so as to allow for adjustment of the spread of the leg screws  70 ,  72 . 
     As various possible embodiments may be made in the above invention for use for different purposes and as various changes might be made in the embodiments and method above set forth, it is understood that all of the above matters here set forth or shown in the accompanying drawings are to be interpreted as illustrative and not in a limiting sense.