Patent Publication Number: US-8969721-B2

Title: Boom tip cover

Description:
TECHNICAL FIELD 
     This document relates to apparatuses and methods for protecting boom tips for use within electrical power transmission systems. 
     BACKGROUND 
     Components such as conductors, equipment, or support structures of electrical transmission systems may present dangers of electrocution to workers operating within the system, either through direct contact with the system or indirect contact for example through the boom of a utility truck. There exist a variety of covers used to insulate components of electrical power systems from short circuits caused by contact. Existing covers have edges that can be spread apart to allow the cover to be placed over the component. 
     SUMMARY 
     A protector is disclosed for a boom tip for use within an electrical power transmission system, the protector comprising: one or more walls having a boom tip enclosure side, an exterior side, and one or more terminal edges that define a boom tip entrance; and a guide shoulder contoured along the boom tip enclosure side to define an installation path for a part of the boom tip to contact and follow relative to the protector. 
     A method is disclosed of installing a protector on a boom tip for use within an electrical power transmission system, the method comprising: positioning the protector so that the boom tip is between one or more terminal edges of the protector, and a part of the boom tip is adjacent an initial portion of a guide shoulder contoured along a boom tip enclosure side of the protector; and advancing the protector into an installed position over the boom tip by allowing the part to follow an installation path defined by the guide shoulder. 
     An apparatus is also disclosed comprising: a boom tip with a dielectric boom tip cover. 
     In various embodiments, there may be included any one or more of the following features: At least a portion of the installation path is directed away from the boom tip entrance. The guide shoulder has at least a first guide portion and a second guide portion, the first guide portion defining a first installation path axis, and the second guide portion defining a second installation path axis that is angled relative to the first installation path axis. At least a portion of the installation path is arcuate. The at least a portion of the installation path that is arcuate defines a pivot axis that passes through the protector. The guide shoulder originates from one of the one or more terminal edges. A second boom tip contact point on the boom tip enclosure side of the one or more walls is displaced from the installation path and oriented to face a first plane defined coplanar with a first boom tip contact point on the guide shoulder when the protector is in a partially installed position. The second boom tip contact point is on a second guide shoulder contoured along the boom tip enclosure side to define a second installation path for a second part of the boom tip to contact and follow relative to the protector. A third boom tip contact point and a fourth boom tip contact point, both on the boom tip enclosure side of the one or more walls, are oriented to face opposite respective faces of a second plane defined parallel to the installation path and perpendicular to the first plane when the protector is in a partially installed position. Both of the third boom tip contact point and the fourth boom tip contact point are each perpendicular to both of the first boom tip contact point and the second boom tip contact point. The third boom tip contact point is on a third guide shoulder contoured along the boom tip enclosure side to define a third installation path for a third part of the boom tip to contact and follow relative to the protector. The guide shoulder comprises two or more first guide shoulders angled relative to one another and contoured along the boom tip enclosure side to define the installation path for the part of the boom tip to contact and follow relative to the protector, and in which the first boom tip contact point is on a first of the two or more first guide shoulders and the fourth boom tip contact point is on a second of the two or more first guide shoulders. The guide shoulder comprises two or more first guide shoulders angled relative to one another and contoured along the boom tip enclosure side to define the installation path for the part of the boom tip to contact and follow relative to the protector. The guide shoulder is formed in a covered slot in the boom tip enclosure side. The one or more terminal edges include a pair of opposed flanges, and the pair of opposed flanges converge towards one another with increasing distance from an initial portion of the guide shoulder. The boom tip is located on a truck. The protector is constructed at least in part with dielectric material. At least a portion of the installation path is arcuate, and advancing further comprises rotating the protector into the installed position. Rotating further comprises wedging open a pair of opposed flanges, of the one or more terminal edges, that converge with increasing radial distance from a pivot axis defined by the protector, in which the flanges are shaped to snap around a backside of the boom tip when in the installed position. The part protrudes laterally relative to a plane defined by the installation path. 
     These and other aspects of the device and method are set out in the claims, which are incorporated here by reference. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       Embodiments will now be described with reference to the figures, in which like reference characters denote like elements, by way of example, and in which: 
         FIG. 1  is a side elevation view of a protector positioned in an initial installation position over a boom tip shown in dashed lines. 
         FIG. 1A  is a side elevation view of the protector of  FIG. 1  positioned in a partially installed position over the boom tip. 
         FIG. 1B  is a front elevation section view of the guide shoulders of the protector of  FIG. 1A  in the partially installed position. 
         FIG. 2  is a side elevation view of the protector of  FIG. 1  positioned in an installed position over the boom tip. 
         FIGS. 3A-D  are perspective views illustrating a sequence of steps involved in installing the protector of  FIG. 1  over the boom tip. 
         FIGS. 4-5  are bottom perspective views of the protector of  FIG. 1 . 
         FIG. 5A  is a view taken along the installation path at the entrance of the covered guide slot of  FIG. 1 . 
         FIG. 6  is a top plan view of the protector of  FIG. 1 . 
         FIG. 7  is a rear end elevation view of the protector of  FIG. 1 . 
         FIGS. 8A and 8B  are side elevation and perspective views, respectively, of a protector for a pipe bus, with the pipe bus illustrated in  FIG. 8A  in dashed lines. 
         FIGS. 9A and 9B  are side elevation and perspective views, respectively, of a protector for a sliding bus, with the sliding bus illustrated in  FIG. 9A  in dashed lines. 
         FIG. 10  is a perspective view of a protected boom tip, from a derrick digger truck, being positioned in an electrical power transmission system. 
     
    
    
     DETAILED DESCRIPTION 
     Immaterial modifications may be made to the embodiments described here without departing from what is covered by the claims. 
     Referring to  FIGS. 1-2 ,  3 A-D, and  4 - 7 , a protector  10  for a boom tip  12  for use within an electrical power transmission system is illustrated. The protector  10  has one or more walls  14  and one or more guide shoulders  16  ( FIGS. 1-2  and  4 - 5 ). Wall  14  may form a cover for the boom tip  12  as shown. There may be more than one walls  14 , for example side walls  14 A and  14 B, rear wall  14 C, and top wall  14 D in the example shown ( FIGS. 4-7 ). Wall  14  may also have a suitable shape such as a cylinder (shown in  FIG. 8B  for example). Wall  14  has a boom tip enclosure side  18 , an exterior side  20 , and one or more terminal edges  22  that define a boom tip entrance  24  ( FIGS. 4-5 ). Enclosure side  18  defines a boom tip enclosure  26 , inside which the boom tip  12  is retained upon installation ( FIG. 2 ). Edge  22  may include plural terminal edges  22 , for example base edges  22 A,  22 B, front edge  22 C, and rear edge  22 D. Edge  22  defines a boom tip entrance  28  ( FIGS. 3A ,  4 - 5 ). 
     Guide shoulder  16  is contoured along the boom tip enclosure side  18  of walls  14  ( FIGS. 4-5 ). Guide shoulder  16  defines an installation path  30  for a part  32 , for example a protrusion extended perpendicular to guide shoulder  16  and installation path  30  as shown, of the boom tip  12  to contact and follow relative to the protector  10  ( FIGS. 1 and 2 ). Thus, guide shoulder  16  may be oriented such that a line  31  normal to guide shoulder  16  is perpendicular to installation path  30  along each point of installation path  30  as shown. Thus, guide shoulder  16  allows boom tip  12  to advance along and into protector  10 , while stopping boom tip  12  from moving laterally off installation path  30 . 
     Guide shoulder  16  may have at least a first guide portion  16 A and a second guide portion  16 B ( FIG. 1 ) that contact part  32  at different stages of an installation cycle. First guide portion  16 A defines a first installation path axis  34 , and the second guide portion  16 B defines a second installation path axis  36  that is angled relative to the first installation path axis  34 . Thus, protector  10  may install by one directional movement followed by another distinct directional movement. Axes  34  and  36  are tangent to portions  16 A, and  16 B, respectively as shown. An example of a protector  10  with only two portion guide portions  16 A and  16 B is shown in  FIG. 8A . However, guide shoulder  16  may have more than two portions  16 A and  16 B, for example if at least a portion or the entirety of guide shoulder  16  is arcuate as shown ( FIG. 1 ). When partially or fully arcuate, at least a portion of the installation path  30  may define a pivot axis  38 . Pivot axis  38  may pass through the protector  10 , for example perpendicular to installation path  30  as shown. In other cases pivot axis  38  may pass outside of protector  10 . Using an arcuate guide shoulder  16  means that the protector  10  cannot merely slide in a single direction off boom tip  12  once installed. Although  FIG. 1  illustrates a fully arcuate guide portion  16 ,  FIG. 9A  illustrates an example where guide shoulder  16  has an arcuate portion  16 C and a linear portion  16 D. The guide shoulder or guide shoulders  16  used in a protector  10  may be designed to impart rotational or translational installation movements over boom tip  12 . 
     Referring to  FIGS. 1 ,  5 , and  5 A, guide shoulder  16  may include more than one guide shoulders, for example guide shoulders  16 ,  40  and  42 , for cooperating to define installation path  30  of part  32 . Guide shoulders  16 ,  40 ,  42  are angled relative to one another and cooperate to each align part  32  along installation path  30 , for example by each stopping part  32  from movement along respective lateral directions  44 ,  46 , and  48  ( FIG. 5A ). Like shoulder  16 , shoulders  40  and  42  are thus normal to installation path  30  as shown. The guide slot  50  may be covered as shown. Other suitable shapes for slot  50  may be used. Shoulder  16  may be defined in a groove, flange or other suitable feature. Part  32  may protrude laterally relative to a plane defined by the installation path. The one or more guide shoulders  16  may be an infinite series of guide shoulders such as that defined by a cylinder in cross section. 
     Referring to  FIGS. 1 ,  2 , and  4 , in addition to guide shoulder  16  a second guide shoulder, for example guide shoulder  60 , may be contoured along the boom tip enclosure side  18 . Guide shoulder  60  may define a second installation path  62  for a second part  64  of the boom tip  12  to contact and follow relative to the protector  10  ( FIG. 1 ). Arrows  63  are used to indicate an initial portion of guide shoulder  60  ( FIGS. 1 and 2 ). As with guide shoulder  16 , guide shoulder  60  may be partially or fully arcuate as shown. During an installation cycle, shown for example in the sequence from  FIG. 1  to  FIG. 2 , planes (not shown) defined coplanar with respective boom tip  12  contact points, for example points  66 A and  68 A ( FIG. 1 ) or points  66 B and  68 B ( FIG. 2 ), of the first guide shoulder  16  and the second guide shoulder  60  face each other. By facing one another in such a manner, shoulders  16  and  60  cooperate to retain boom tip  12  between shoulders  16  and  60  and prevent undesired rotation in the example shown. Also, shoulders  16  and  60  each restrict movement of respective parts  32  and  64 , ensuring that boom tip  12  is guided properly into the installed position shown in  FIG. 2 . Guide surface  60  may track along a curved surface, such as provided by second part  64 , on the boom tip  12 , with the curved surface defining the pivot axis  38 . The part  32  may extend in a direction parallel to pivot axis  38  so that boom tip  12 . 
     Referring to  FIGS. 1A ,  1 B, and  3 C, some embodiments of protector  10  may be understood by considering how protector  10  functions in a partially installed position. In this example, a first boom tip contact point  66 C and a second boom tip contact point  68 C are illustrated, with point  68 C being on the boom tip enclosure side  18  of the one or more walls  14  ( FIG. 1A ). Second boom tip contact point  68 C is illustrated as being displaced from the installation path  30  of guide shoulder  16 , and oriented to face a first plane  67  defined coplanar with first boom tip contact point  66 C ( FIGS. 1A ,  1 B, and  3 C). For ease of illustration, installation path  30  and first plane  67  denote the same dashed line in  FIG. 1A , although for installation path  30  this line is understood to denote a line, while for first plane  67  the line is intended to denote a plan perpendicular with the page. Second boom tip contact point  68 C may be on the second guide shoulder  60  as shown. 
     Third and fourth boom tip contact points  69 C and  71 C, respectively, may also be defined on the boom tip enclosure side  18  of the one or more walls  14  ( FIG. 1B ). Third and fourth boom tip contact points  69 C and  71 C are oriented to face opposite respective faces  73 A,  73 B of a second plane  73  defined parallel to the installation path  30  and perpendicular to the first plane  67 . In some cases such as the one illustrated both of the third boom tip contact point  69 C and the fourth boom tip contact point  71 C are each perpendicular to both of the first boom tip contact point  66 C and the second boom tip contact point  68 C. The third boom tip contact point  69 C may be on a third guide shoulder  88  contoured along the boom tip enclosure side  18  to define a third installation path  90  for a third part  92  ( FIG. 3A ) of the boom tip  12  to contact and follow relative to the protector  10  ( FIG. 1B ). As shown, the first boom tip contact point  66 C is on a first of the two or more first guide shoulders  16 , for example guide shoulder  17 , and the fourth boom tip contact point  71 C is on a second of the two or more first guide shoulders  16 , for example guide shoulder  40 . A fourth guide shoulder  60 B may be provided similar to guide shoulder  60 . These combinations guide shoulders restrain the boom tip  12  from movement in certain undesired directions during installation, and thus improve installation. Once the protector  10  is located in the initial position ( FIG. 1 ), a push from almost any suitable point on the protector  10  will allow the protector to close as shown due to the guiding action of the guide shoulders. 
     Referring to  FIG. 1 , at least a portion of the installation path  30  may be directed away from the boom tip entrance  28 . In some cases the guide shoulder  16  originates from one of the one or more terminal edges  22 . As the boom tip  12  enters entrance  28 , boom tip  12  tracks into the boom tip enclosure via guide shoulder  16  present on the boom tip enclosure side of walls  14 . Entrance  28  may face into the direction of rotation  61  of protector  10  relative to the boom tip  12 . 
     Referring to  FIG. 10 , the boom tip  12  may be for use within transmission system  15 . For example boom tip  13  may be located on a truck  11  such as a derrick digger truck as shown. Thus, the protector  10  may be shaped as a boom tip cover as shown. A boom tip  13  may be used to carry various payloads  19  within the vicinity of an electrical power transmission system  15 , in this case overhead power lines  21 . Parts  32  and  92  may be the ends of a cable axle  29  of boom tip  13  ( FIGS. 1B and 3A ). Protector  10  may have an underside cable passage or opening  39  for a boom cable  41 . In other cases, protector  10  may be designed to fit components  12  that form part of electrical power transmission systems. For example, referring to  FIG. 8A , protector  10  is shaped to cover the end  76  of a pipe bus  78 . Referring to  FIG. 9A , protector  10  is shaped to cover a sliding bus  80 . Other shapes and applications may be used. 
     Referring to  FIGS. 1 ,  2 , and  3 A-D, an exemplary method of installing a protector  10  on a boom tip  12  for use within an electrical power transmission system is illustrated. In a first stage, the protector  10  is positioned so that the boom tip  12  is between one or more terminal edges  22 , and a part  32  of the boom tip  12  is adjacent an initial portion  72  of guide shoulder  16  (FIGS.  1  and  3 A-B). In a second stage the protector  10  is advanced into an installed position ( FIG. 3D ) over the boom tip  12  by allowing the part  32  to follow an installation path  30  ( FIG. 1 ) defined by the guide shoulder  16  ( FIGS. 2 ,  3 C-D). Boom tip entrance  28  may also point downwards when installed as shown. 
     Referring to  FIGS. 3B ,  3 D, and  5 , the one or more terminal edges  22  may include a pair of opposed flanges  70 . The pair of opposed flanges  70  may converge towards one another with increasing distance from an initial portion  72  of the guide shoulder  16  ( FIGS. 3B and 5 ). Flanges  70  may converge with increasing radial distance from pivot axis  38  if guide shoulder  16  is designed to rotate relative to the boom tip  12  on advancement. Such convergence helps the flanges  70  be progressively wedged outwards during installation instead of improperly bending inward into boom tip enclosure  26 . As the boom tip  12  enters the boom tip entrance  28  during install, the flanges  70  are wedged open ( FIG. 3B ). However, once the boom tip  12  is in the installed position, the flanges  70  may close, for example by snapping, around a backside  74  of the boom tip  12  ( FIG. 3D ). Lips or flanges  70  may restrict removal of protector  10 . 
     The protector  10  may be made at least in part with dielectric material. The dielectric material may comprise a single part material or multiple part material mixed before application, and may be formulated from a combination of liquid and semi-solid or solid boom tips. Electrical transmission system may refer to any apparatus intended to transmit power. It will be understood that the teachings equally apply and may be adapted to any commercially used voltage range or any suitable transmission system. Adhesive, for example pre-applied on the protector  10 , may be used to affix the protector  10  to the boom tip  12 . 
     Non conductive protectors  10  are advantageous because they allow users  54  to encroach on the safe limits of approach. For example, with a protector  10  in place a user  54  is allowed to make accidental brush contact with the protector  10  while the system is energized. 
     Photogrammetry may be used to determine the shape of the boom tip  12 , and determine the location of suitable parts  32  for corresponding guide shoulders  16 , and determining other relevant characteristics of protector  10  such as the pivot axis or inner contour of boom tip enclosure side  18 . 
     Guide shoulder  16  may have more than one arcuate portions with varying radii of curvature. Protector  10  may be designed to use combinations of translational and rotational installation movements. Guide shoulders  16  may allow ninety degrees or less of rotation. Edges  22  may be secured together after installation, for example using fasteners, for further example through cooperating flanges. Shoulder  16  may be defined by an uncovered slot, for example a slot with shoulders  42  and  16  but lacking shoulder  40  ( FIG. 5A ). The guide shoulder or shoulders may span more than one wall  14 . Opposed pads  94  may grip the boom tip  12  and may assist in defining a hinge point at pivot axis  38  to close the protector  10  over boom tip  12  ( FIG. 3 ). Each installation path, such as paths  30 ,  62 , and  90  may be a range of paths defined by the relevant volume of the respective part  32 ,  64 , and  92  that is guided by the local or nearest respective guide shoulder. More than 4 guide shoulders may be present. Each guide shoulder may be a covered slot. Boom tip contact points are points on the protector  10  where the installation cycle position has the parts located nearest to or in contact with the respective contact point. Contact is not required in use other than to restrain the protector  10  to ensure proper installation. Protectors  10  may be designed with ample clearance between boom tip  12  and protector  10  walls  14 , even between guide shoulder and respective boom tip part, in order to reduce jamming during installation. Each guide shoulder may satisfy the first, second, third, and fourth boom tip contact criteria at two, more than two, a majority, or all partially installed positions. Directional words such as up or down are understood to be relative phrases and are not intended to be limited to being defined relative to the surface of the earth. 
     In the claims, the word “comprising” is used in its inclusive sense and does not exclude other elements being present. The indefinite articles “a” and “an” before a claim feature do not exclude more than one of the feature being present. Each one of the individual features described here may be used in one or more embodiments and is not, by virtue only of being described here, to be construed as essential to all embodiments as defined by the claims.