Abstract:
An attachment for a tool used to attach and remove load break elbows and protective caps from bushings disposed on a transformer is provided. The tool attachment includes an elbow engaging member that is positionable around a load break elbow or cap fixed to a bushing. The engagement member is fixedly secured to a horizontal bar that includes a number of aligned openings extending through the bar. These openings are selectively alignable with a pair of openings disposed on a vertical bar to pivotally attach the vertical and horizontal bars to one another. The vertical bar also includes an opening through which a pulling eye on the elbow or cap can extend when the tool attachment is positioned on the elbow or cap. A conventional pulling tool can be attached to the eye as it extends through the vertical bar and utilized in conjunction with a pulling rope secured to the vertical bar opposite the pivoting connection in order to quickly and easily remove the elbow or attach the elbow to a bushing without causing extended arcing.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]    This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application No. 60/293,573, filed May 25, 2001, the entirety of which is incorporated by reference herein. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates to tools for connecting and disconnecting loadbreak elbows and protective caps positioned on bushings disposed on an electrical distribution transformer, loadbreak junction or standoff insulator and more specifically to an attachment used with an elbow pulling tool.  
         DESCRIPTION OF THE RELATED ART  
         [0003]    Electrical distribution transformers are used for voltage transformation in a distribution system. Transformers designed for underground cable connections have been used by electrical utilities since the late 1960s and include insulated bushings that protrude from the transformer. The bushings are designed to connect to cables connected to a power source opposite the bushings that supply high voltage electricity to the transformer. The cables feeding the high voltage to the transformer commonly terminate with a pre-molded loadbreak elbow. A loadbreak elbow is essentially an insulated connector attached to the end of an electrical cable that is designed to plug into the transformer bushings so that the elbow may be disconnected under load.  
           [0004]    The bushing is an insulated structure made from ceramic, a plastic, rubber, or the like. The insulating material forming the bushing prevents energized cables connected to the transformer from coming into contact with one another. When the bushing is not in use, an insulated protective cap is to cover the open, unused bushing.  
           [0005]    Typically, the elbow or cap and bushing components are coated with a lubricating substance like a silicone grease to aide in connecting and disconnecting the elbow or cap to and from the bushing. However, over time the silicone grease tends to harden, and loses its effectiveness due to, for example, heat-aging. As a result, a firm, cementeous bond is established between the elbow or cap and the bushing, making the elbow or cap extremely difficult to disconnect from the bushing. Further, this problem is often aggravated since in most occasions the elbows or caps are disconnected from the bushings very infrequently, often after a number of years of use, which allows the grease to become extremely hard.  
           [0006]    To assist in the removal of the elbows or caps which are stuck to a bushing, both the loadbreak elbow and protective cap are designed with an integral pulling eyelet located on the elbow or cap opposite the bushing. The eyelet is designed for use with tools specifically designed to engage the eyelet and remove the elbow or cap from the bushing.  
           [0007]    Over the years there have been several tools designed for this particular use of engaging the pulling eyelet to remove stuck elbows and caps. One of these types of tools is known in the industry as a “hotstick.” A hotstick is a tool used by utility operating personnel during the connection and disconnection of loadbreak elbows and protective caps from the bushings. A hotstick is essentially an elongated, insulated rod with a manually manipulatable gripper assembly at one end that selectively engages the pulling eye and permits the removal of the elbow even when the cable contained within the elbow is energized. One particular type of hotstick know as a “shotgun” has a gripper assembly that includes a hook that engages the eyelet on the elbow that is moved into and out of engagement with the eye by a collar slidably mounted to the rod and connected to the hook. However, due to the lack of any mechanical advantage provided by the hotstick, the hotstick is often unsuccessful, even after repeated attempts, in disconnecting an elbow or cap that is seized onto the bushing by hardened silicone grease.  
           [0008]    As a result, a number of alternative hotstick designs have been created to mechanically aid the operator of the tool in engaging the pulling eyelet to more easily remove the elbow from the bushing. For example, U.S. Pat. No. 3,534,993 (Le Vesque) describes a hotstick and clamping mechanism incorporated into one tool. The working end of the tool includes vinyl coated jaws disposed on manually manipulatable operating arms formed of chrome-plated vinyl. The tool can be rotated to engage the end of the elbow within the jaws that form snuggly around the elbow as the tool grasps the elbow. The jaws operate to hold the elbow stationary while the tool is operated to ease the removal of the elbow.  
           [0009]    Another example is U.S. Pat. No. 4,483,058 (Clutter), which discloses an impact hammer elbow tool. This tool has an integral hook disposed between a pair of movable gripping jaws on the tool head that fits through the pulling eye of an elbow or a bushing cap. The tool also includes a tubular hammer that can selectively engage an anvil disposed on the tool to deliver a force to the elbow in order to attach or remove the elbow from the bushing.  
           [0010]    Each of the above-mentioned tools have, however, proven to be less than satisfactory in disconnecting loadbreak elbows from transformer bushings. Specifically, these devices do not provide a sufficient force directed to the elbow to allow the elbow to be quickly removed from the bushing. In situations when an electrical load is applied through the cable disposed within the bushing and elbow, the slow removal of the elbow from the bushing allows arcing to occur between the elbow and the bushing, which creates a significant risk to the individual removing the elbow. Accordingly, it is desirable to develop an improved loadbreak elbow pulling tool that allows an elbow to be removed more quickly.  
         SUMMARY OF THE INVENTION  
         [0011]    It is an object of the present invention to provide an elbow or protective cap pulling tool apparatus capable of effectively transmitting the pulling force of the pulling tool to the elbow or cap to effect a quick release of the elbow or cap from a bushing.  
           [0012]    It is another object of the present invention to provide a pulling tool attachment that can be utilized with a wide range of conventional operating sticks.  
           [0013]    It is still another object of the present invention to provide a pulling tool attachment that can be utilized with elbows installed on varying styles and makes of components.  
           [0014]    It is still further object of the present invention to provide a pulling tool attachment that has a simple and easy to utilize construction.  
           [0015]    The present invention is an attachment for an elbow pulling tool that increases the effectiveness and the transmission of the pulling force from the tool to the elbow to effect a quicker and less dangerous release of the elbow from a bushing disposed on a transformer. The tool attachment includes a guide tube adapted to be positioned around a horizontal portion of an elbow that is secured to the bushing. The guide tube supports an adjuster bar that includes a number of aligned pairs of apertures spaced from the guide tube. A lever is pivotally secured to the adjuster bar by a removable pin inserted through the lever and one of the aligned pairs of apertures in the adjuster bar. The lever also includes an opening alignable with the pulling eye extending outwardly from the elbow opposite the bushing. The opening enables a conventional hotstick or shotgun stick to be attached in a known manner to the eye which extends through the opening in the lever. Also, the lever includes a pulling rope mounting hole opposite the adjuster bar to which a hook can be releasably attached that is secured to one end of a pulling rope.  
           [0016]    To use the tool attachment to remove an elbow secured to a bushing on a transformer, in a preferred method first the pin is positioned in the appropriate pair of aligned apertures for the elbow to be removed. The tool attachment is then positioned around the elbow such that the guide tube encircles the elbow and abuts and engages the base of the bushing. The pulling rope and hotstick are then attached to the rope mounting hole and pulling eye, respectively, and a rearward force is applied to the lever and pulling eye through both the rope and hotstick. This rearward force pivots the lever with respect to the adjuster bar and guide tube, urging the guide tube forwardly into engagement with the base of the bushing, and enabling the elbow seal to be broken, followed by a quick removal off of the bushing.  
           [0017]    Other objects and advantages of the present invention will be made apparent from the following detailed description taken together with the drawing figures. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    Preferred exemplary embodiments of the invention are illustrated in the following drawings.  
         [0019]    In the drawings:  
         [0020]    [0020]FIG. 1 is a side elevation view of an elbow pulling tool attachment constructed in accordance with the invention positioned on a load break elbow;  
         [0021]    [0021]FIG. 2 is a top plan view of the elbow pulling tool attachment of FIG. 1;  
         [0022]    [0022]FIG. 3 is a front elevation view of the elbow pulling tool attachment of FIG. 1;  
         [0023]    [0023]FIG. 4 is a perspective view of the elbow pulling tool attachment of FIG. 1;  
         [0024]    FIGS.  5 - 7  are consecutive side elevation views illustrating the steps for using the elbow pulling tool attachment to remove a loadbreak elbow from a transformer bushing; and  
         [0025]    [0025]FIG. 8 is a perspective view of a second embodiment of the tool attachment of FIG. 1. 
     
    
     DETAILED DESCRIPTION  
       [0026]    Before explaining embodiments of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments or being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting the invention.  
         [0027]    With reference now to the drawing figures in which like reference numerals represent like numerals throughout the disclosure, an elbow pulling tool attachment is indicated generally at  10  in FIG. 1. The tool attachment  10  is designed to be utilized with a standard elbow pulling tool or hotstick  12 , such as a shotgun stick, which utility companies use in installing and removing loadbreak elbows  14  and/or insulated protective caps (not shown). The tool attachment  10  is used with the hotstick  12  to remove insulated plug members, such as protective caps and load break elbows  14 , disposed on transformer bushings  16 , or on a conventional feed through module (loadbreak junctions) or stand off (not shown) as are known in the art. An example of a suitable hotstick  12  is the Serial No. 3100 tool made by Hastings of Hastings, Mich.  
         [0028]    The construction of the tool attachment  10  described herein is adaptable to remove elbows  14  and caps used with these bushings  16  in multiple applications. More specifically, there are three voltage classes for load break systems: namely, 15 kilovolts (KV), 25 KV, and 35 KV. A single tool attachment  10  is able to remove elbows  14  attached to both the 15 KV and 25 KV components because of their similarity in size. A separate size tool attachment  10  is required for the 35 KV Cooper Industries components because they are significantly larger than the 15 KV and 25 KV components.  
         [0029]    The elbows  14  are generally L-shaped including a horizontal portion  18  engaged with the bushing  16  that extend outwardly from the transformer  17  and includes a base  19  disposed against the transformer  17 , and a vertical portion  20  perpendicularly connected to the horizontal portion  18  and disposed opposite the bushing  16 . A pulling loop or eye  22  is disposed on the vertical portion  20  and extends in a direction opposite the horizontal portion  18 . The elbow  14  can be formed of an insulating material, such as rubber, and the eye  22  is formed of a steel-reinforced rubber material secured to the elbow  14 .  
         [0030]    Referring now to FIGS.  1 - 4 , in a preferred embodiment the elbow pulling tool attachment  10  includes a guide/push tube  24 , an adjuster bar  26  attached to the tube  24 , and a channel lever  36  pivotally attached to the adjuster bar  26  by a clevis pin  38 .  
         [0031]    The guide/push tube  24  is generally cylindrical in shape and is formed with a partial cylindrical side wall  28  that includes a longitudinal slot  30  extending along the entire length of the tube  24 . The side wall  28  has a diameter that is at least slightly larger than the diameter of the horizontal portion  18  of the elbow  14 , and a length approximately equal to the length of the horizontal portion  18 . The slot  30  is positioned such that the side wall  28  preferably covers an angle of approximately 2350 from one end of the slot  30  around the side wall  28  to the opposite end of the slot  30 . However, the slot  30  may also be reduced or enlarged in size such that the angle formed by opposite ends of the slot  30  is between 200° and 270°, so long as the slot  30  is narrower than the width of the horizontal portion  18  and larger than the width of the vertical portion  20  of the elbow  14  such that the tube  24  can effectively engage the horizontal portion  18  of the elbow  14 . The tube  24  is also preferably made of a clear material such that the elbow  14  or cap being removed by the tool attachment  10  can be easily seen through the tube  24  when the tool  10  and tube  24  are attached to the elbow  14 . However, the tube  24  can be formed of any suitable generally rigid, electrically insulative material.  
         [0032]    The adjuster bar  26  is generally rectangular in shape and includes a pair of attachment openings  31  disposed adjacent first end  32  of the adjuster bar  26 , a number of pairs of aligned openings  33  spaced from the first end  32  and one another and extending through the bar  26 , and a second end  34  opposite the first end  32  and including a bore  35  extending therethrough perpendicular to openings  33 . The adjuster bar  26  is secured to the tube  24  by the insertion of a pair of screws  40  through openings  42  in the tube  24  disposed directly opposite the slot  30 . The screws  40  extend outwardly from the openings  42  and through the attachment openings  31  in the adjuster bar  26 , and are secured therein by a pair of nuts  44  threadably engaged with the screws  40  opposite the tube  24 . The adjuster bar  26  is preferably formed of a generally rigid material, and includes indicia  45  printed on one side of the adjuster bar  26  which indicate where the lever  36  should be pivotally attached to the adjuster bar  26  in order to remove an elbow  14  having a specific size, as the openings  33  serve to align the particular cap or elbow  14  with the pivot point of the bar  26  and lever  36 .  
         [0033]    The clevis pin  38  used to pivotally attach the channel lever  36  to the adjuster bar  26  insertable through one of the aligned pairs of openings  33  disposed on the adjuster bar  26 . The pin  38  is also inserted through a pair of aligned apertures  50  disposed on opposite sides of the channel lever  36 . The lever  36  is generally rectangular in shape and includes a central body portion  52  with tool positioning indicia  53  and a pair of opposed side walls  54  that extend perpendicularly outwardly from opposite sides of the body portion  52  parallel to one another. The central body portion  52  includes an upper opening  55  disposed adjacent one end of the body portion  52  in alignment with the apertures  50  located in each side wall  54 . The upper opening  55  is generally rectangular in shape and is adapted to receive the adjuster bar  26  therethrough, such that the pairs of aligned openings  33  on the adjuster bar  26  can be selectively aligned with the apertures  50  disposed in the side walls  54 . Thus, the clevis pin  38  can be inserted through the apertures  50  and aligned openings  33  to pivotally secure the adjuster bar  26  and channel lever  36  to one another. Further, to increase the strength of the lever  36  around the apertures  50 , a pair of reinforcing plates  56  are disposed on the side walls  54 . The plates  56  include openings  57  aligned with the apertures  50 , and are secured to the side walls by screws  58 . The plates  57  can be disposed on either side of the side walls  54  and are preferably formed of a material similar to that of the lever  36 .  
         [0034]    The channel lever  36  also includes a middle opening  59  disposed within the body portion  52  below the upper opening  56 . The middle opening  59  is adapted to be positioned against the corner of the elbow  14  such that the pulling eye  22  can extend through an upper, cross-like portion  60  of the middle opening  59 . The cross-like portion  60  is able to allow an eye  22  that is oriented in a horizontal or vertical plane on the elbow  14 . The middle opening  59  also includes a lower oval portion  62  that is adapted to receive the eye  22  therethrough such that the gripping end of the hotstick  12  can be secured to the eye  22 .  
         [0035]    Finally, the channel lever  36  includes a lower opening  64  disposed approximately opposite the upper opening  55  that is generally oval in shape and is adapted to enable a pulling rope  66  to be secured to the lever  36 . The rope  66  includes a detachable hook  68  secured to one end that can be selectively opened and inserted through the lower opening  64  in order to secure the rope  66  to the lever  36  at the lower opening  64 .  
         [0036]    Referring now to FIGS.  5 - 7 , in order to remove an elbow  14  from a bushing  16  extending outwardly from a transformer  17 , initially the adjuster bar  26  is inserted through the upper opening  55  in the channel lever  36  until the desired pair of aligned openings  33  are in alignment with the opposed apertures  50  in the side walls  54  of the lever  36 . A 90° angle between adjuster bar  26  and channel lever  36  is the optimum position. The pin  38  is then inserted through the apertures  50  and the selected pair of aligned openings  33  to pivotally secure the adjuster bar  26  and channel lever  36  to one another.  
         [0037]    After the adjuster bar  26  is secured to the lever  36 , the hotstick  12  is engaged with the bore  35  on the second end  34  of the adjuster bar  26 . After the hotstick  12  is rigidly attached to the adjuster bar  26 , the attachment  10  is positioned in alignment with the elbow  14  such that the pulling eye  22  is aligned with the cross-like portion  60  of the middle opening  59 . The attachment  10  is then slid over the elbow  14 , such that the tube  24  is positioned around the horizontal portion  18  of the elbow  14 , and the pulling eye  22  extends through the middle opening  59 . The hotstick  12  is then removed from the adjuster bar  28 , leaving the tool attachment  10  engaged with the elbow  14 .  
         [0038]    With the tool attachment  10  positioned on the elbow  14 , the hook  68  (which is attached to the pulling rope  66 ) is inserted through the lower opening  64  on the lever  36 . The hook  68  is engaged with the lower opening  64  such that the hook  68  and rope  66  cannot become disengaged from the lever  36  while the tool attachment  10  is being utilized. In a preferred embodiment, the hook  68  is formed similarly to a carabiner having a pivoted and spring-biased portion  70  of the hook  68  being movable to releasably attach the hook  68  to the lower opening  64 .  
         [0039]    The hotstick  12  is then reengaged with the pulling eye  22  in a conventional manner, and the hotstick  12  and pulling rope  66  are pulled upwardly and rearwardly with respect to the elbow  14  in the direction indicated by arrows A in FIG. 7. Initially, the hotstick  12  and rope  66  are pulled rearwardly at the same time with a slow, steady pull or force applied to the elbow  14 , until a release of the elbow  14  from the bushing  16  is felt through the hotstick  12  and rope  66 . This force is transmitted to the base  19  of the bushing  16  by the tube  24 , such that the force exerted on the hotstick  12  by the individual both pulls the elbow  14  via the eye  22 , and pushes the elbow  14  away from the bushing  16  via the tube  24 .  
         [0040]    More specifically, when using the attachment  10 , the particular positioning of the hotstick  12  and rope  66  on the tool attachment  10  provides an approximate 6:1 mechanical advantage in removing the elbow  14  from the bushing  16 , such that the tool attachment  10  allows any hardened lubricant between the elbow  14  and the bushing  16  to be easily broken. After the release is felt, the hotstick  12  and rope  66  are pulled quickly in a rearward direction to completely remove the elbow  14  from the bushing  16 . Further, with the ability of the hotstick  12  and rope  66  to move the elbow  14  a relatively large difference in a short time the removal of the elbow  14  using the tool attachment  10  avoids dangerous arcing conditions that can result from a slower, gradual load break using only the hotstick  12 . After the elbow  14  is removed, it can be positioned on a stand-off insulator (not shown) positioned on the transformer  17  by using the attachment  10  and tool  12  to push the elbow  14  onto the insulator.  
         [0041]    It is understood that various preferred embodiments are shown and described above to illustrate different possible features of the invention and the varying ways in which these features may be combined. For example, the configuration of the middle opening  59  can be attached to have the configuration shown in FIG. 8 with a lower oval portion  62  and a narrower upwardly extending portion. Further, the particular pivoting attachment between the adjuster bar  26  and the lever  36  can take the alternative form of a sliding pin fixed within the lever  36  or bar  26 , or one or more spring-biased pins disposed within the lever  36  or bar  26 . Apart from combining the different features of the above embodiments in varying ways, other modifications are also considered to be within the scope of the invention by the following claims which particularly point out and distinctly claim the subject matter regarded as the invention.