Patent Publication Number: US-11047147-B2

Title: L-shaped crossarm, related system, and method of assembly

Description:
RELATED APPLICATIONS 
     The present patent document claims the benefit of the filing date under 35 U.S.C. § 119(e) of Provisional U.S. Patent Application Ser. No. 62/506,113, filed May 15, 2017, which is hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure generally relates to a crossarm used in power transmission systems, systems including a crossarm, and methods of assembly. 
     BACKGROUND 
     Power transmission systems often include above-ground utility poles for suspending electrical power lines. The utility poles are traditionally made from wood, steel, or concrete. When multiple power lines or other related components are supported, a utility pole may include a horizontal crossarm and a crossarm bracket. Crossarms are typically formed of wood, steel, or polymer materials (e.g., plastic or fiberglass), and may be secured to the utility pole through a variety of hardware components. The crossarm may provide support for one or more suspended power lines. For example, the crossarm may be secured to a ceramic or polymer insulator that attaches directly to a suspended power line. 
     Over time, wood crossarms may deteriorate and rot due to weather, thereby decreasing the strength of the wooden crossarm and necessitating replacement. A wooden crossarm can absorb moisture and become a poor electrical insulator. As such, there is a risk of electricity traveling through the wooden crossarm, which can pose a risk of electrocution to a line technician. Additionally, wooden crossarms can suffer from variations in strength do to inherent flaws within the wood. 
     Exposure of steel crossarms to the weather elements can cause corrosion, and therefore may also present their own robustness problems. Additionally, steel crossarms lack electrical insulating properties that are desirable for electrical power applications. 
     In some instances, crossarms are formed of a hollow tube. Unless the cavity of the hollow tube is filled with some type of material or otherwise closed off, birds, animals, and insects may inhabit the cavity, causing damage to certain components, presenting safety concerns, and/or interfering with maintenance operations. A non-filled or sealed hollow tube may also retain moisture, which may degrade the crossarm over time or promote electrical activity. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is perspective view of a system with a crossarm and a mounting base in accordance with the present disclosure. 
         FIG. 2  is a cut-away interior view of a crossarm in accordance with the present disclosure. 
         FIG. 3  is a profile view of the crossarm of  FIG. 1 . 
         FIG. 4  is a perspective view of a crossarm in accordance with the present disclosure. 
         FIG. 5  is a perspective view of the mounting base of  FIG. 1 . 
         FIG. 6  is a perspective view of an alternate mounting base for use with separate crossarms. 
         FIG. 7  is an exploded view of a system with two crossarms and a mounting base in accordance with the present disclosure. 
         FIG. 8  is a perspective view of a crossarm and detachable braces in accordance with the present disclosure. 
         FIG. 9  is a perspective view of a crossarm in accordance with the present disclosure. 
         FIG. 10  is a perspective view of a crossarm in accordance with the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Various aspects are described below with reference to the drawings, and several of the elements are identified by numerals. The relationship and functioning of the various elements may better be understood by reference to the following description. However, aspects are not limited to those illustrated in the drawings or explicitly described below. The drawings are not necessarily to scale, and in certain instances, details may have been omitted that are not necessary for an understanding of aspects disclosed herein. 
     In this application, the use of the disjunctive is intended to include the conjunctive. The use of definite or indefinite articles is not intended to indicate cardinality. In particular, a reference to “the” object or “a or an” object is intended to denote also one of a possible plurality of such objects. 
       FIG. 1  is a perspective view of a system  100  with crossarm  102  and mounting base  104 . In some non-limiting exemplary embodiments, the crossarm  102  may have a generally L-Shaped cross-section such that a first section  106  and a second section  108  may be generally perpendicular to one-another. Additional embodiments may generally take the shape of other rigid structural member profiles, such as an I-beam (as shown in  FIG. 9 ) or a T-beam. As shown in  FIG. 1 , the first section  106  may extend away from the second section  108 . Although  FIG. 1  illustrates the second section  108  pointing in a generally downward direction (e.g., a generally reversed L-Shaped geometry), it is contemplated that, depending on the mounting location, crossarm  102  could be rotated such that the second section  108  is pointing in a generally upward direction (e.g., generally L-Shaped geometry). 
     Crossarm  102  may be extruded, fabricated, or formed from a composite material having a generally uniform cross-section extending in a longitudinal direction. In some embodiments, the composite material may be a reinforced plastic formed by drawing resin-coated glass fibers through a heated die, such as a pultruded fiberglass.  FIG. 2  shows a cut-away interior view of a crossarm  102  with fibers  110  that are located within a material  112 , such as a plastic for example. An outer coating  114  may cover the material  112  for added protection and/or strength. The crossarm  102  may be continuously fiber reinforced, such that fibers  110  extend the length of the crossarm  102 , as shown in  FIG. 2  for example. The length the fibers  110  extend can be any dimension of the crossarm  102 , such as a longitudinal length or a transverse length. Alternatively, the crossarm  102  may be discontinuously fiber reinforced, such that fiber  110  do not extend the length of the crossarm  102 . The length of fibers  110  in discontinuously fiber reinforced crossarms may vary from several inches to less than a millimeter. Fibers  110  in discontinuously fiber reinforced crossarms may, for example, be composed of chopped glass. 
     Crossarm  102  may be a contiguous structure and may, as shown in  FIG. 3 , have a rounded or slightly curved interior surface. In some instances, this rounded interior surface may aid in the insertion of the crossarm  102  into an opening on the mounting base  104 . Alternatively, crossarm  102  may be a discontiguous structure formed by connecting separate sections  106  and  108  together with fasteners or adhesives to create the generally L-shaped geometry of the crossarm. Even when fasteners or adhesives are used to connect separate sections  106  and  108  of a crossarm, the final crossarm may still have a rounded interior surface. As described in more detail below, the crossarm  102  may be suitably secured to the mounting base  104  with a fastening element. 
     Crossarm  102  may include reinforcement portions to help crossarm  102  resist torsion and/or bending.  FIG. 4  shows a non-limiting exemplary embodiment of crossarm  102  with a reinforcing rib  116  located on the exterior of first section  106  and reinforcing tab  118  on an interior edge of second section  108 . As shown in  FIG. 4 , the reinforcement tab  118  extends from a distal end of the second section  108  along the interior edge. The reinforcement portions may resist torsion and/or bending by affecting the moment of inertia of the crossarm. The reinforcement portions may take any form that improves the resistance to torsion and/or bending, such as ribs, tabs, splines, dimples, or ridges. The reinforcement portions may be located anywhere on the crossarm and may be added during formation of the crossarm or as part of post-formation processing. 
     One or more attachment assemblies (not shown) may be used to secure suspended power lines or insulators to crossarm  102 . In some embodiments, an attachment assembly may be one or more hardware plates, clasping members, and fastening devices that are used with existing utility poles. As a result, a crossarm in accordance with the disclosed embodiments may be backwards compatible with existing hardware. Alternatively, new attachment assemblies configured for use with the generally L-Shaped geometry of crossarm  102  or configured to mount to separately to sections  106  or  108  could also be used to secure suspended power lines or insulators to crossarm  102 . 
     The length of crossarm  102  may be customized depending on use. In some instances, crossarm  102  may have a length-width footprint of approximately three feet by four feet. A crossarm  102  with these approximate dimensions may also be lightweight, weighing approximately 10 pounds to approximately 15 pounds. However, in other instances and depending on a particular need, crossarm  102  may have a longer/shorter and/or wider/thinner length-width footprint. As the footprint of crossarm  102  changes, so would the approximate weight of each crossarm. The lightweight nature of crossarm  102 , however, is advantageous for ease of transportation, and during installation or removal of the crossarm and system. The generally L-shaped geometry of crossarm  102  also provides for easy packaging and storing, as multiple crossarms can be aligned in a similar orientation in order that they may be stacked together. 
     Crossarm  102  may be adapted for multiple different uses. Where an existing utility pole crossarm has degraded, crossarm  102  and mounting base  104  may be used as a replacement. Alternatively, crossarm  102  and mounting base  104  may also be used for new installations. 
       FIG. 5  is a perspective view of mounting base  104 . Mounting base  104  includes an opening  502  that is complementary in shape to a cross-sectional profile of crossarm  102 , and therefore configured to receive crossarm  102 . Crossarm  102  may be aligned with opening  502  of mounting base  104  and slid through opening  502  until a desired position of mounting base  104  is reached. Crossarm fastening hole  504  may be used to hold crossarm  102  in place within mounting bracket  104 . Opening  502  may be formed between a front-facing fastening surface  506  and a rear-facing surface  508 . In some embodiments, crossarm fastening hole  504  may extend through the entirety of the front-facing fastening surface  506 , but not through the rear-facing surface  508 . The crossarm fastening hole  504  may be configured (e.g., sized, shaped, and positioned) to receive a fastener (not shown). The fastener may be a screw, bolt, wedge, anchor, pin, hook, or other suitable device. When the fastener is threaded, the crossarm fastening hole  504  may include corresponding mating threads. When mounting base  104  only includes a crossarm fastening hole  504  that extends through a front-facing fastening surface  506 , crossarm  102  may be fixed within the mounting base  104  by inserting or tightening the fastener through the crossarm fastening hole  504  such that the fastener exerts a force against the a portion of section  108  of a crossarm  102  and an interior surface the rear-facing surface  508 . 
     Although  FIG. 5  depicts mounting base  104  with a crossarm fastening hole  504  that extends only through the entirety of the front-facing fastening surface  506 , it is contemplated that a corresponding and mating rear-crossarm fastening hole can be formed in rear-facing surface  508 . In this configuration, crossarm fastening hole  504  and rear-crossarm fastening hole would share similar sizes, shapes, and, depending on the configuration, threadings, and be aligned along a common axis. In this configuration, crossarm  102  may be fixed within mounting base  104  by inserting a fastener (as described above) through crossarm fastening hole  504 , crossarm  102 , and rear-crossarm fastening hole. During installation of the crossarm  102  and mounting base  104  to a utility pole, the fastener could also be secured into a mounting surface, such as a utility pole, thereby providing added support to prevent the mounting base  104  and crossarm  102  from moving over time. Preparation of the fastener through the crossarm fastening hole  504 , crossarm  102 , and rear-crossarm fastening hole could be done in advance of or during installation of the system to a mounting surface. It is further contemplated that crossarm  102  could include a hole that would receive the fastener and that would align with the crossarm fastening hole  504  and rear-crossarm fastening hole. 
     Mounting base  104  may also be configured with a mounting section  510 . Mounting section  510  may be an extension of the rear-facing surface  508 , such that the rear surface of mounting section  510  and rear-facing surface  508  are aligned along a similar plane. As shown in  FIG. 5 , a front surface  512  of mounting section  510  may be setback from front-facing fastening surface  506 . That is the front-facing fastening surface  506  may extend over less that an entire portion of the height of the rear-facing surface  508 . A support  514  may connect front-facing fastening surface  506  and an inner portion of rear-facing surface  508 . Support  514  may extend through an entire width of the mounting base, and may hold a portion of crossarm  102  when crossarm  102  has been inserted through opening  502 . 
     A mounting hole  516  is formed in mounting section  510 . Mounting hole  516  may extend through the entirety of mounting section  510 . The mounting hole  516  may be configured (e.g., sized, shaped, and positioned) to receive a mounting fastener (not shown). The mounting fastener may be a screw, bolt, wedge, anchor, pin, hook, or other suitable device. When the mounting fastener is threaded, the mounter hole  516  may include corresponding mating threads. 
     During the fabrication process, opening  502  may be created by any of a number of cutting techniques, such as plasma cutting, laser cutting, waterjet cutting, or any other suitable method for creating opening  502 . 
     In a second embodiment of an L-shaped crossarm and mounting base system, a mounting base  604  may be configured without a crossarm fastening hole, as shown in  FIG. 6 . In such an embodiment, one or more mounting clasps (not shown) may be positioned within opening  602 . Smaller crossarms may be used in connection with mounting base  604 . Rather than sliding a crossarm through the entirety of the opening  602 , an edge of a first crossarm may be inserted through a first side of opening  602 . An internal abutment or stop positioned at or near the middle of opening  602  along the width of mounting base  604  may prevent the first crossarm from being inserted any further than midway through opening  602 , and may cause a first retaining assembly to retain the first crossarm in place. A second crossarm could be inserted into the opposite side of mounting base  604  through an opening opposite  602 . The second crossarm could be inserted until the internal abutment or stop is reaching, causing a second retaining assembly to retain the second crossarm in place. For example,  FIG. 7  shows an exploded view of two crossarms  702 ,  704  that can be inserted into a mounting base  706 . Each mounting assembly may include one or more springs or a retaining mechanism, such as lip, ram, or biased tabs that will exert a force on the inserted crossarm to retain it in place within mounting base  604 . In some configurations, a quick release button or latch may be provided on an exterior portion of the mounting base  604 . Actuating the quick release button or latch may cause an associated retaining assembly to release a crossarm. In such configurations, one quick release button or latch could cause all retaining assemblies to release, but other configurations could have separate quick release buttons or latches so individual crossarms at different times. Use of the mounting assemblies and quick release buttons or latches may be advantageous when it comes to replacing or decommissioning a crossarm. 
     In some embodiments, mounting base  604 , may include self-leveling springs within its openings ( 602  and corresponding opening on the opposite side of mounting base  604 ). The self-leveling springs may cause the separately inserted crossarms to level to an approximately horizontal plane even though mounting base  604  may not have been positioned at a horizontal plane when fixed to a mounting surface. 
     Some embodiments of crossarm  102  may be attached to a structure, such as a utility pole, without a mounting base.  FIG. 8  shows crossarm  102  attached to a utility pole through detachable braces  802 . In  FIG. 8 , crossarm  102  may be attached directly to the utility pole through hole  804  with a fastener and also attached to the utility pole through detachable braces  802 . The fastener may be a screw, bolt, wedge, anchor, pin, hook, or other suitable device. When the fastener is threaded, the hole  804  may include corresponding mating threads. Alternatively, crossarm  102  may be attached to a structure using both a mounting base and detachable braces. The attachment assemblies to secure suspended power lines or insulators to crossarm  102  may be secured to attachment apertures, as show in  FIG. 8 . 
     Although specific embodiments have been described with a crossarm having a composite material that may be a reinforced plastic formed by drawing resin-coated glass fibers through a heated die, such as a pultruded fiberglass, crossarms created by other processes and composite materials made be used within the scope of the present disclosure. For example, in another embodiment, the crossarm composite material may be a fiberglass created from an alternate forming process. Such alternate processes may exclude the use of a mandrel to form the fiberglass. Excluding the use of a mandrel may form a fiberglass crossarm without interior cavities, which may improve the strength and durability of the crossarm. In yet other embodiments, the crossarm composite material may be an armed fiber material or a polyester fiber material. In still yet other embodiments, crossarm composite material may be created utilizing multiple mat layers of material that are bonded together for strength and stability. For example,  FIG. 9  shows a crossarm  902  with an I-beam shaped cross-section. Crossarm  902  is composed of a sandwich structure such that an inner material  904  is located between layers of outer material  906 . The outer material  906  may be a reinforced plastic composite, as previously discussed. The inner material  904  may be a lightweighting structure, such as a structural foam or honeycomb material, that is lighter weight than the outer material  906 . The use of a lightweighting structure will reduce the overall weight of the crossarm  902  and may also reduce its cost.  FIG. 10  shows another example embodiment of a crossarm  1002  composed of a sandwich structure with inner material  1004  and outer material  1006 . The sandwich structures may include multiple layers of lightweighting structure and reinforced plastic composite in any order or any amount of layers. For example,  FIG. 9  shows two adjacent layers of lightweighting structure sandwiched between outer layers of reinforced plastic composite. 
     Additionally, it is contemplated that alternative configurations of the mounting base are within the scope of the present disclosure. For example, in another embodiment, a mounting base of the types described in  FIGS. 1, 5, 6 and 7  could have a rear-facing surface that includes a curvature that complements the shape of a curved mounting surface, such as a utility pole. Additionally, a mounting base of the types described in  FIGS. 1, 5, 6 and 7  could have a sandwich structure, as described in relation to  FIGS. 9 and 10 . 
     Specific embodiments have been described for the purpose of illustrating the manner in which the aspects of the present disclosure are user. It should be understood that the implementation of other variations and modifications of the embodiments described herein and their various aspects will be apparent to one skilled in the art, and that the invention is not limited by the specific embodiments described herein.