Abstract:
A cable clamp ( 10 ) includes two interchangeable half-portions ( 14, 16 ). Each half-portion ( 14, 16 ) includes an outer side, an inner side including a cable receiving region ( 18, 20 ), a hinge region ( 30, 32 ) arranged below the cable receiving region ( 18, 20 ), and a suspending region ( 70 ) arranged above the cable receiving region ( 18, 20 ). The suspending region ( 70 ) is adapted to receive an associated support element ( 72 ). The two half-portions ( 14, 16 ) are adapted to cooperatively form a unitary cable clamp body having a cable channel ( 22 ) defined by the two cable receiving regions ( 18, 20 ) and a hinge ( 36 ) including the two hinge regions ( 30, 32 ). A tightener ( 54 ) is arranged above the cable channel ( 22 ) for drawing the half-portions ( 14, 16 ) together about the hinge ( 36 ) to clamp an associated cable ( 12 ) within the cable channel ( 22 ).

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to the cable suspension arts. It particularly relates to apparatus and methods for suspending high tension cables mounted aerially using poles or other overhead support structures, and will be described with particular reference thereto. However, the invention also finds application in conjunction with other uses where cables for the transmission of power or communication signals are fastened, clamped, affixed, or otherwise mechanically supported or constrained, such as in the suspension of optical ground wires (OPGW&#39;s).  
           [0002]    Power cables are frequently suspended aerially from poles or other support structures. An aerial arrangement of such cables has the advantages of relatively simple and flexible installation having a limited ground footprint, and permits space substantially below the cables to be used for other purposes. An aerial arrangement also separates the cables from contact with people or roaming ground animals. Spatial separation is particularly important for high tension electrical power transmission cables for safety reasons. Separation of any cable helps protect the cable from damage caused either inadvertently or through malicious vandalism.  
           [0003]    Although aerial cables are relatively safe from ground-based sources of damage, they are subject to environmental wear and damage, principally due to winds. Well known in the art are problems caused by aeolian vibration which is a high frequency, low amplitude vibration caused by laminar winds passing across the line, as well as galloping which is a low frequency, high amplitude wind-induced cable motion. Aeolian vibration, galloping, and other wind action can produce cable damage especially at the suspension points where cable clamps and other supporting devices mechanically stress the cable. Cable damage in the form of abrasion, wear, and fatigue can occur especially at the clamping points.  
           [0004]    The prior art includes a large number of cable clamp styles. A type of clamp commonly used for high tension power cable suspension employs a pair of upper and lower clamp body portions that sandwich the cable in vertical fashion (top-and-bottom) and are clamped using bolts, rods, or other fasteners. These cable clamps are formed from a plurality of parts which remain separate until assembly in the field. This being the case, the bolts, rods, or other fasteners are susceptible to misplacement or mishandling in the field, particularly in rainy, snowy, or other adverse weather conditions. The fastening of the clamp usually requires simultaneous manipulation of both a bolt and an associated fastening nut in order to effectuate the clamping. This requires two hands, and can be particularly problematic when installing the clamp on an electrified cable. Furthermore, two dissimilar clamp body portions are paired to form the clamp body, further increasing the possibility of encountering missing clamp parts during field assembly. As the two clamp halves are mounted above and below the cable, the clamping force is added to the weight-induced bending stress of the cable.  
           [0005]    U.S. Pat. No. 2,887,669 issued to J. Sylvester discloses a cable connector having two identically formed clamp body portions, which reduces the number of differentiated parts. U.S. Pat. No. 3,633,858 issued to H. J. Houston et al. discloses a spring clamp in which the spring clamp member is held against a rigid clamp member using an adjustable bolt. In both these clamps, the cable is retained near an outer edge of the clamp device, which limits the security of the clamping. The cable is also not surrounded by retaining hardware, and so the cable can be lost in the event of clamp slippage.  
           [0006]    U.S. Pat. No. 5,435,507 issued to M. W. Murphy discloses a cable support for installation on a rigid pole. This clamp is operatively similar to the Houston clamp except that the spring clamp member is replaced by a second rigid clamp member. The two rigid clamp members are dissimilar.  
           [0007]    The present invention contemplates an improved cable clamp which overcomes the aforementioned limitations and others.  
         SUMMARY OF THE INVENTION  
         [0008]    According to one aspect of the invention, a cable clamp including two interchangeable half-portions is provided. Each half-portion includes an outer side, an inner side including a cable receiving region, a hinge region arranged below the cable receiving region, and a suspending region arranged above the cable receiving region. The suspending region is adapted to receive an associated support element. The two half-portions are adapted to cooperatively form a unitary cable clamp body having a cable channel defined by the two cable receiving regions and a hinge including the two hinge regions. A tightener is arranged above the cable channel for drawing the half-portions together about the hinge to clamp an associated cable within the cable channel.  
           [0009]    According to another aspect of the invention, a piece is disclosed, including an outer side, an inner side having a cable receiving region, a hinge region arranged below the cable receiving region, and a suspending region arranged above the cable receiving region, the suspending region adapted to receive an associated support element. The piece is adapted to cooperate with a similar piece to form a unitary cable retaining body having a cable channel defined by cooperating cable receiving regions, a hinge including cooperating hinge regions and an associated hinge fastening element, and a clamping element arranged to pivotally close the cooperating pieces about the hinge.  
           [0010]    According to another aspect of the invention, a cable-retaining device is disclosed. A hinged pair of elements are adapted to receive an associated cable therebetween. A clamp is adapted to compress the hinged pair of elements together to fasten about the associated cable.  
           [0011]    According to yet another aspect of the invention, a cable clamp is disclosed. A first body member and a second body member cooperate to form a unitary clamp body. The clamp body has a cable channel, a hinge region arranged on a side of the cable channel, and a compression region arranged on an opposite side of the cable channel away from the hinge region. A hinge fastener hingeably attaches the first and second body members in the hinge region. A clamp draws the first and second body members together in the compression region to compressively hold an associated cable arranged within the cable channel.  
           [0012]    According to still yet another aspect of the invention, a cable clamp is disclosed. A left clamp member and a right clamp member together define a clamp body. A hinge is formed into a lower portion of the clamp body. A tightening member is disposed in an upper portion of the clamp body. A cable channel formed into the clamp body is arranged between the hinge and the tightening member.  
           [0013]    One advantage of the present invention is that the clamp body is constructed from two identical, interchangeable portions, which simplifies manufacturing and assembly.  
           [0014]    Another advantage of the present invention is that it includes a clamping operation employing a nondetachably attached hinge and captive hardware to reduce or eliminate the number of separate parts which must be assembled in the field.  
           [0015]    Another advantage of the present invention is that the cable is securely retained in a cable channel arranged away from edges of the clamp.  
           [0016]    Another advantage of the present invention is that the clamp can be pre-assembled and placed as a single unit onto a hot, electrified cable using an insulated lifting pole. This simplifies installation of the suspension clamp onto hot wires, and makes the installation safer.  
           [0017]    Another advantage of the present invention is that the clamping action occurs horizontally (i.e., left-and-right) at right angles to the cable weight-induced bending stress.  
           [0018]    Yet another advantage of the present invention is that the bolt-and-nut fasteners are received by recesses adapted to receive at least one of the bolt head and the nut in non-rotatable fashion. In this way, the bolt-and-nut fastener can be tightened using only the bolt head or only the nut.  
           [0019]    Still yet another advantage of the present invention is that the clamp includes one or more cushions that reduce mechanical stress on bending portions of the clamped cable.  
           [0020]    Numerous additional advantages and benefits of the present invention will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]    The invention may take form in various components and arrangements of components, and in various steps and arrangements of steps. The drawings are only for the purpose of illustrating preferred embodiments and are not to be construed as limiting the invention.  
         [0022]    [0022]FIG. 1 shows an isometric view of an exemplary cable suspension clamp that suitably practices an embodiment of the invention.  
         [0023]    [0023]FIG. 2 shows the embodiment of FIG. 1 with a connecting element for suspending the clamp and affixed cable from a support structure.  
         [0024]    [0024]FIG. 3 shows an exploded isometric view of the clamp of FIG. 1.  
         [0025]    [0025]FIG. 4 shows a preferred method for inserting a cable into the clamp of FIG. 1 without disassembling the hinge of the clamp.  
         [0026]    [0026]FIG. 5 schematically shows the hinge and the tightener acting on each of the pair of clamp body portions to form cooperating second-class levers that compressively fasten onto the associated cable.  
         [0027]    [0027]FIG. 6 shows an enlarged isometric view of the nut portion of an exemplary bolt-and-nut fastener inserted into the oblong hole having a recess for non-rotatably holding the nut, and staking pins for capturing the fastener hardware.  
         [0028]    [0028]FIG. 7 shows an isometric view of one body piece of another exemplary cable suspension clamp that includes a lifting hole.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0029]    With reference to FIGS. 1 through 6, an exemplary cable suspension clamp  10  that suitably practices an embodiment of the invention is described. The clamp  10  is used to aerially suspend an associated cable  12  from a support wire, support post extension, or other supporting structure (not shown). In the first preferred embodiment of FIGS. 1 through 4, the cable  12  is a bare (uninsulated) aluminum conductor cable of a type known in the art for transmitting electrical power at high voltages such as in the kilovolt range. However, the cable clamp is readily adapted to function with essentially any type of cable, including lower power electrical distribution cables, telephone cables, cable television cables, fiber optical cable bundles such as optical ground wires (OPGW&#39;s) known to the art, and the like. For supporting optical fibers, a helical structural reinforcing rod (not shown) formed of aluminum or a similar material is selectively provided for improving the structural integrity of the clamping.  
         [0030]    The clamp  10  includes a main clamp body formed from two body portions  14 ,  16 . In the clamp  10 , the two body portions  14 ,  16  are identically formed and interchangeable, thus simplifying manufacturing and assembly of the clamp  10 . However, it is to be appreciated that the body portions  14 ,  16  can be selectively formed to be non-interchangeable as desired. For example, one body portion may be modified to include an integral support bracket (not shown) for mounting directly to a pole or other support means (not shown). In the preferred embodiment, the body portions  14 ,  16  are cast aluminum pieces for supporting high tension power transmission cables. However, other metals, composites, plastics, or the like can also be used, particularly for power cables transmitting at low power or for communication cables.  
         [0031]    The body portions  14 ,  16  define a pair of opposed cable receiving regions  18 ,  20  that cooperate to form a cable channel  22  which holds the clamped portion of the cable  12 . Additionally, cable cushions  24  are provided as needed in the cable channel  22  near the ends of the cable channel  22 . The cushions  24  absorb wind-induced vibrations and reduce cable abrasion, wear, and fatigue. The cushions  24  are formed of EPDM, neoprene, silicone, or other suitable material using extrusion or compression molding.  
         [0032]    Each of the body portions  14 ,  16  include a hinge region  30 ,  32  that cooperate with one another and with a set of bolt-and-nut fastener pairs  34  to form a hinge  36 . Hinging action is obtained when the fasteners  34  are inserted through oblong holes  40  (best seen in FIG. 3) in the hinge regions  30 ,  32 . The oblong holes  40  allow the bolt-and-nut fastener pairs  34 , when loosened, to articulate within fixed limits established by the size of the oblong holes  40  and the extent of loosening of the fasteners  34 . The articulation allows the body portions  14 ,  16  to pivot essentially about a hinge axis  42 , as shown in FIG. 4. The pivoting opens a compression region  50  arranged on an opposite side of the cable channel  22  away from the hinge regions  30 ,  32 , through which the cable  12  is inserted, as best seen in FIG. 4. In a suitable cable installation process, the fasteners  34  are loosened only enough so that the compression region  50  can be opened sufficiently to insert the cable  12 . The body portions  14 ,  16  remain hingeably connected in the hinge region  36  throughout the cable  12  installation.  
         [0033]    After the cable  12  is received in the cable channel  22 , the clamp  10  is tightened to effectuate clamping. The fasteners  34 , which were preferably only slightly loosened to allow cable installation, are re-tightened. Additionally, a tightener member  54  cooperates with the compression region  50  to compress the body portions  14 ,  16  against the cable  12  by hingeably pivoting the body portions  14 ,  16  about the hinge  36 . The cushions  24  are also compressed against the cable  12 . Alternatively, the cushions  24  extend into the hinge region  36  and are compressed by the hinge as well. This reduces the possibility that the cushions  24  will slip out of place during clamp  10  installation, and provides a more stable cushioning for the cable  12  at the regions where it extends out of the clamp  10 .  
         [0034]    In the preferred embodiment, the tightener member  54  includes a bolt-and-nut fastener  34  of the same type used in forming the hinge  36 , which passes through holes  56  in the compression region  50  of the body portions  14 ,  16 . The holes  56  are best seen in FIG. 3.  
         [0035]    Those skilled in the art will recognize that the preferred embodiment illustrated in FIGS. 1 through 4 is exemplary only. Other equivalent mechanical arrangements can be used to construct the hinge  36  and the tightener  54 .  
         [0036]    With reference to FIG. 5, a schematic diagram shows the hinge  36  and the tightener  54  acting on each of the pair of clamp body portions  14 ,  16  to form cooperating second-class levers  60 ,  62  that compressively fasten onto the associated cable  12 . As second-class levers  60 ,  62 , the resistance  64  is arranged between the fulcrum (corresponding to the hinge  36 ) and the applied force  66  generated by the tightener  54 . The second-class lever operation shown in FIG. 5 occurs in pure form only if the hinge fasteners  54  are tightened prior to applying the tightener  54 . This closely approximates the preferred operation, since the hinge fasteners  34  are preferably only slightly loosened to allow cable  12  insertion and are then tightened at least partially before inserting and applying the tightener  54 .  
         [0037]    However, in the preferred embodiment of the subject clamp illustrated in FIGS. 1 through 4, it is contemplated that once the cable is inserted and the fasteners  34  and tightener  54  are “finger-tight”, that the hinge fasteners  34  are tightened essentially together with the tightener  54  to effectuate firm clamping of the cable  12 . That is, although the hinge  36  operates as a swinging hinge for cable  12  insertion and initial clamping, the final tightening (e.g., using a wrench or other tools) of the clamp  10  is performed using both the tightener  54  and the fasteners  34  of the hinge regions  30 ,  32 . This promotes an even and firm clamping force that is produced by tightening elements  34 ,  54  on both sides of the cable  12 .  
         [0038]    With continuing reference to FIGS. 1 through 4, during use, the clamp  10  is suspended via a suspending region  70  arranged in the clamp  10  essentially coincident with the compression region  50 . Cable and clamp suspension is obtained using a transverse rod  72  secured in holes  74  of the suspending region  70 . The rod  72  is secured in the suspending region  70  using a cotter pin  76 . The inserted rod  72  is used as a connecting means for connecting the clamp  10  to a support. For example, in FIG. 2 an associated supporting loop  80  is shown. The suspending region  70  is exemplary only, and many other equivalent configurations are also contemplated. Further, the suspending region  70  need not be coincident with the compression region  50 . For example, it is also possible to arrange the suspending region into the hinge  36 , or to modify one or both of the two clamp body portions  14 ,  16  to form a suspending region therein.  
         [0039]    With particular reference next to FIGS. 2 and 5, those skilled in the art will recognize that the configuration of the clamp  10  advantageously produces a clamping force  64  in the horizontal plane directed at right angles (substantially perpendicular) to a bending stress  68  generated by the cable weight. This reduces the maximum total stress on the cable. The cushions  24  in particular are pressed toward the cable  12  from the left-and-right, and these forces do not additively combine with the bending stress  68 .  
         [0040]    With continuing reference to FIGS. 1 through 4, and with further reference to FIG. 6, the clamp  10  further alleviates problems with loose and missing parts that were frequently encountered in prior cable clamps by arranging the nut portions of the fasteners  34  as captive hardware. As best seen in FIG. 6, the nut is inserted into a recess  90  formed into the oblong hole  40 . The recess  90  has flat inwardly facing surfaces that match the outer faces of the nut thereby holding the nut in place in a non-rotating fashion. Once the nuts are so inserted, staking pins  92  which are preferably cast into the body portions  14 ,  16  are deformed and pressed toward the nut to secure and retain the nut in the recess  90 . In addition to retaining the nut, this arrangement also holds the nut in non-rotating fashion so that the bolt-and-nut fastener  34  can be tightened using only one wrench or other tool applied to the bolt head. The arrangement of FIG. 6 is also preferably applied to the nut of the tightener  54 . Those skilled in the art will also appreciate that the fasteners  34  can alternatively have the bolt of the bolt-and-nut fastener  34  non-rotatably retained in the described manner, in which case the nut remains free for selective tightening.  
         [0041]    With reference to FIG. 7, a modified body portion  100  is described of a second preferred embodiment. The body portion  100  is essentially similar to the body portions  14 ,  16  except that it includes a lifting hole  102 . The lifting hole  102  is used to lift the clamp in an upside-down orientation over and onto an electrified high tension cable  12 , using an associated fiberglass or other insulating lifting pole (not shown). The clamp hinge  36  is left open during the lifting with the tightener  54  removed (except optionally for a retained captive nut). The clamp is draped onto the hot installed cable  12 . The human installer then inserts and partially tightens the tightener  54  and the fasteners  34 , rotates the clamp into the appropriate position for suspension, and completes the clamping. The recesses  90  advantageously hold the nuts in place rotatably relative to the housing members to simplify the tightening operation. Thus, the installation is easy and safe for the installer.  
         [0042]    In one test, a clamp manufactured in accordance with the preferred embodiment of the invention described above underwent 23,000,000 vibration cycles with a large vibration amplitude equal to the diameter of the clamped cable. The cable exhibited no breaks inside the clamp, and the clamp exhibited no failures.  
         [0043]    In a short circuit test, a clamp formed in accordance with the invention was used to support a cable carrying a 1000 ampere current to test the thermal integrity of the clamp. No failure was observed, and in particular the cushions were undamaged.  
         [0044]    The invention has been described with reference to the preferred embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the invention be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.