Abstract:
A cantilever assembly includes a cantilever arm having a pair of longitudinal fastening channels with a corresponding pair of slots in communication with the fastening channels. An attachment bracket features a connector portion and a pair of spaced leg portions defining a seat there between with each leg portion having at least one aperture. The leg portions also each have an inner surface featuring an elongated groove with each being in communication with a corresponding one of the apertures. The elongated grooves are positioned in alignment with the slots of the cantilever arm when the cantilever arm is positioned in the seat of the attachment bracket. Tee bolts having a shaft portion and an oblong head portion movably pass through the apertures of the attachment bracket with the oblong head portions pivotable between a first orientation where they may be positioned within the elongated grooves of the attachment bracket and passed through the slots and into and out of the fastening channels of the cantilever arm, and a second orientation where they are secured within the fastening channels of the cantilever arm.

Description:
FIELD OF THE INVENTION 
     The present invention relates to overhead contact systems in the transit traction power industry and, more particularly, to a cantilever assembly for such systems. 
     BACKGROUND 
     Electrified train transit systems are popular in urban settings due to their low level of pollution and high efficiency and reliability. Such transit systems typically feature an electric locomotive that pulls train cars for carrying passengers and that receives power from an overhead contact system. Overhead contact systems typically feature messenger and contact wires that are suspended over the track that the electric train cars travel on. The top of the electric locomotive is provided with a pantograph which contacts the contact wire so that the locomotive receives power. 
     The messenger and contact wires are typically suspended by a cantilever assembly, such as the one indicated in general at  8  in  FIG. 1 . As illustrated in  FIG. 1 , the cantilever assembly includes two or more insulated, rigid cantilever arms, illustrated at  10  and  12 , that are attached by their proximal ends via members  14  and  16  to a pole  18  positioned next to the tracks. The distal end of the lower cantilever arm  12 , which features a tilted orientation, is typically attached to the underside of the upper cantilever arm  10 , which is positioned in a generally horizontal orientation. As a result, the lower cantilever arm provides support for the upper cantilever arm. A messenger saddle  20  is typically positioned at the distal end of the upper cantilever arm. A steady arm  21  is typically attached by its proximal end to the lower cantilever arm, and an insulated swivel clamp  22  for the contact wire is typically positioned at the distal end of the steady arm. The messenger passes over the saddle  20  and its ends are connected to the contact wire by hangers to form a bridal assembly where the contact wire is suspended by both the swivel clamp  22  and the messenger cable. 
     As is clear from the above, the cantilever assembly, which includes the upper and lower cantilever arms and the steady arm, are critical components for securing and maintaining contact and messenger wire heights and locations in an overhead contact system. Steel pipe is typically used for the upper and lower cantilever arms and the steady arm. This makes the components heavy and difficult to handle and install. A need therefore exists for a cantilever and steady arms that provide a reduction in weight. 
     As is also likely apparent from the above, the cantilever assembly must be properly configured for optimal performance. In addition, a large number of cantilever assemblies must be assembled and installed for an overhead contact system. As illustrated in  FIG. 1 , prior art cantilever assemblies typically use clevis pipe clamps  24  and  26  to secure the distal end of the lower cantilever arm to the underside of the upper cantilever arm and to secure the proximal end of the steady arm to the lower cantilever arm. Such clamps feature a number of different parts that are difficult to handle during installation and may become easily separated and lost. In addition, assembly and tightening of the clamps is time consuming. A need therefore also exists for a fastening bracket for the cantilever and steady arms of a cantilever assembly that is quick and easy to install and that remains as a single assembly during installation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side elevational view of a prior art cantilever assembly; 
         FIG. 2  is a perspective view of an embodiment of the cantilever assembly of the invention; 
         FIG. 3  is an enlarged perspective view of the attachment bracket of the cantilever assembly of  FIG. 2 ; 
         FIG. 4  is an enlarged perspective view of the tee bolt of the cantilever assembly of  FIG. 1 ; 
         FIG. 5  is a perspective view of two tee bolts of the type illustrated in  FIG. 4  installed on the attachment bracket of  FIG. 3 ; 
         FIG. 6  is a sectional view taken along line  6 - 6  of  FIG. 2  illustrating installation of the attachment bracket on the lower cantilever arm of  FIG. 2 ; 
         FIG. 7  is an enlarged perspective view of the distal ends of the upper and lower cantilever arms with the attachment brackets and other components installed. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     An embodiment of the cantilever assembly of the present invention is indicated in general at  30  in  FIG. 2 . The assembly includes an upper cantilever arm  32 , a lower cantilever arm  34  and a steady arm  36 . The upper and lower cantilever arms  32  and  34  and the steady arm  36  are each preferably extruded from aluminum. The steady arm preferably includes an inverted U-shaped cross section to provide weight and material savings while providing rigidity. Alternative materials, such as plastics or composites, and manufacturing methods may alternatively be used for each component. In accordance with the present invention, the three components are secured together with attachment brackets  42 ,  44  and  45 , as described in greater detail below. Attachment brackets  42 ,  44  and  45  are also preferably extruded from aluminum. A messenger saddle  46  is positioned on the distal end of the upper cantilever arm  32 , while a contact wire swivel clamp  48  is attached to the distal end of the steady arm  36 . 
     The outside diameter of the upper and lower cantilever arms  32  and  34  preferably matches that of a steel pipe (typically 2.375 inches). This allows the attachment of hardware already designed for a nominal 2 inch pipe. 
     An enlarged view of attachment bracket  42  is provided in  FIG. 3 . Attachment bracket  44  features a similar appearance and construction. As is apparent from  FIG. 3 , the attachment bracket features a generally Y-shaped cross section with a bottom fin connector portion  52  and upwardly extending leg portions  54   a  and  54   b . The inner surfaces  56   a  and  56   b  of leg portions  54   a  and  54   b  define a generally U-shaped seat  57  and are provided with elongated grooves  58   a  and  58   b , respectively. A pair of openings  62  and  64  are provided in fin connector portion  52 . In addition, apertures  66   a ,  66   b ,  68   a  and  68   b  are provided in the leg portions with apertures  66   a  and  68   a  in communication with elongated groove  58   a  and apertures  66   b  and  68   b  in communication with elongated groove  58   b . The number of openings and apertures shown are examples only and the fin and leg portions of the attachment bracket may be provided with more or less openings and apertures as is suitable for the application. 
     A tee bolt for use with the attachment bracket of  FIGS. 2 and 3  is indicated in general at  72  in  FIG. 4 . The tee bolt includes an oblong head portion, indicated in general at  74 . The oblong head features side portions  76  and  78  and corner portions  80 ,  82 ,  84  and  86 . The tee bolt also includes a threaded shaft  88  with one end adjacent to the oblong head portion  74 , and the other end provided with tool engagement portion, which in this embodiment is a recess  92 . Alternative tool engagement portions may be used in place of recess  92  and include a bolt head or any other protrusion or recess that may be engaged by a tool for turning the tee bolt. The tee bolt may be constructed as a single piece or constructed as two pieces that are joined. The tee bolt preferably is constructed from metal. 
     As illustrated in  FIG. 5 , tee bolt  72  and tee bolt  73  (which features a construction identical to tee bolt  72 ) pass through apertures  66   a  and  68   a  ( FIG. 4 ) of leg portion  54   a  of the attachment bracket  42 . The threaded shaft of each tee bolt has a diameter that is sized smaller than the diameters of apertures  66   a  and  68   a  so that the threads of the tee bolt threaded shafts do not engage the apertures (which are not threaded) as the tee bolts pass there through. Lock nuts  94  and  95  engage the threaded shafts  88  and  89  of the tee bolts so that they do not become separated from the attachment bracket prior to installation and for use during installation, the latter of which will be explained below. 
     With reference to  FIG. 5 , when the lock nuts  94  and  95  are positioned near the ends of the tee bolts opposite the oblong head portions, as shown for lock nut  95 , the oblong head portion of the corresponding tee bolt (in this case oblong head portion  75 ) may be moved into the U-shaped seat  57  as the tee bolt shaft  89  slides through the corresponding aperture ( 68   a  in  FIG. 3 ) in attachment bracket leg portion  54   a . The oblong head portions  74  and  75  of the tee bolts and the elongated groove  58   a  are sized so that the oblong head portions may be positioned within the elongated groove when the oblong head portion is oriented as shown in  FIG. 5  for oblong head portion  74  of tee bolt  72 . When the oblong head portions of the tee bolts are oriented as shown for oblong head portion  75 , however, the oblong head portion does not fit within the elongated groove  58   a . Tee bolts engage apertures  66   b  and  68   b  of attachment bracket leg portion  54   b  in the same fashion. 
     As illustrated in  FIG. 6 , lower cantilever arm  34  features a central cylindrical bore  100  that is flanked by longitudinal fastening channels  102   a  and  102   b . Fastening channels  102   a  and  102   b  feature side opening slots  103   a  and  103   b  (see also  FIGS. 2 and 7 ). In order to provide weight and material savings, the cantilever arm  34  preferably includes generally square ducts  104 ,  106  and generally triangular ducts  108 ,  110 ,  112  and  114  that run parallel to central bore  100  and fastening channels  102   a  and  102   b . Central bore  100  is preferably threaded so that components such as insulator  116  ( FIG. 2 ) may be attached to the cantilever arm. Upper cantilever arm  32  ( FIG. 2 ) features the same construction as lower cantilever arm  34 . Alternative embodiments of the upper and lower cantilever arms may optionally eliminate, or vary the shape of, some or all of the square and triangular ducts, as well as the central bore. In addition, alternative embodiments of the cantilever arms may feature an overall cross section that is a shape other than round (such as octagonal, square, triangular, etc.). Of course the shape of the leg portions and seat of the attachment bracket would have to be changed accordingly. 
     Prior to installation of the attachment bracket, the tee bolts are preferably configured as illustrated by tee bolt  72  in  FIGS. 5 and 6 . More specifically, the oblong head portion  74  of the tee bolt is secured within the elongated groove  58   a  by tightening lock nut  94  against the exterior surface of leg portion  54   a  of the attachment bracket. By configuring all four tee bolts in this fashion, their movement with respect to the attachment bracket is prevented, thus greatly reducing the chance that any of the locks nuts will loosen and become lost, along with the corresponding tee bolts. In addition, this configuration greatly simplifies installation of the attachment bracket to a cantilever arm. 
     With reference to  FIG. 6 , the attachment bracket  42  is easily and quickly attached to the lower cantilever arm  34  by placing the cantilever arm within the seat  57  of the attachment bracket (as illustrated in  FIGS. 2 and 6 ). This is easily accomplished because all of the oblong heads of the tee bolts are positioned in the elongated grooves  58   a  and  58   b  of the leg portions of the attachment bracket. As illustrated in  FIG. 6 , the height of slots  103   a  and  103   b  of channels  102   a  and  102   b  of the cantilever arm, illustrated at  117  for slot  103   a , is approximately the same as the height of grooves  58   a  and  58   b , illustrated at  119  for groove  58   b  in  FIG. 5 , of the leg portions of the attachment bracket. The dimensions of the seat  57  of the attachment bracket also correspond to the diameter and positions of the slots  103   a  and  103   b  of the cantilever arm so that the slots align with the elongated grooves when the cantilever arm is positioned within the seat  57 . 
     In reference to  FIG. 6 , with the lower cantilever arm  34  positioned in the seat  57  of the attachment bracket, the lock nut  118  of tee bolt  122  is loosened, and the oblong head portion  124  of the tee bolt is moved inward into the fastening channel  102   b . A screwdriver is then used to engage the recess  126  of the tee bolt and pivot or turn it so that the oblong head portion of the tee bolt is pivoted within the fastening channel  102   b . When this occurs, corner portions  82  and  86  ( FIG. 4 ) of the oblong head portion of the tee bolt engage the top and bottom surfaces  132  and  134  ( FIG. 6 ) of the fastening channel  102   b , respectively. The top and bottom edges of the slot  103   b  prevent the oblong head portion of the tee bolt from being withdrawn from the fastening channel  102   b . Locking nut  118  is then tightened to the position illustrated in  FIG. 6  to lock the tee bolt in position. The operation is repeated for the remaining tee bolts of the attachment bracket. As a result, the attachment bracket  42  is quickly and securely fastened to the lower cantilever arm as illustrated in  FIG. 2 . 
     With reference to  FIG. 2 , the steady arm  36  is attached at its proximal end  140  by a connector  142  to the fin  52  of the attachment bracket  42 . The connector  142  is secured to the fin by a bolt or other fastener  144  that passes through opening  62  ( FIG. 3 ) of the fin  52 . 
     With reference to  FIG. 2 , the proximal ends  146  and  148  of insulators  116  and  151  are adapted to be mounted to a support such as a wall or pole (not shown), in the matter illustrated in  FIG. 1  for the latter. The insulators may be excluded so that the proximal ends of the upper and lower cantilever arms  32  and  34  are instead attached to the pole or wall. 
     As illustrated in  FIG. 7 , attachment bracket  44  is attached to the upper cantilever arm  32  in the same fashion described above with reference to  FIGS. 2-6  for attachment bracket  42  and lower cantilever arm  34 . As with bracket  42 , attachment bracket  44  features a connector portion in the form of a downwardly extending fin  152 . An attachment bracket  45  is attached to the distal end of the lower cantilever arm  34  in the same fashion described above with reference to  FIGS. 2-6  for attachment bracket  42  and lower cantilever arm  34 . Attachment bracket  45  features a construction and operation similar to attachment brackets  42  and  44 , except it features a pair of spaced fins  154  and  156  as the connector portion, instead of the single fin  52  of attachment bracket  42  ( FIG. 3 ) and the single fin  152  of attachment bracket  44 . The connector portion of the attachment bracket may take many other forms to attach to various other components. As shown in  FIG. 7 , the single fin  152  of attachment bracket  44  is positioned between the fins  154  and  156  of attachment bracket  45 . The pieces are secured together by a bolt or other fastener  162  that passes through corresponding openings in the fins  152 ,  154  and  156 . 
     As noted above, a messenger seat  46  is attached to the distal end of the upper cantilever arm. This may be accomplished by a bracket  164  that operates in a fashion similar to attachment brackets  42 ,  44  and  45 . 
     The above embodiment of the present invention therefore provides a lightweight but rugged and durable structure whereby the components are quickly and securely fastened together. The above embodiment also allows for quick adjustment of the cantilever assembly and allows other components to be quickly, easily and securely attached to the upper and/or the lower cantilever arms. 
     While the preferred embodiments of the invention have been shown and described, it will be apparent to those skilled in the art that changes and modifications may be made therein without departing from the spirit of the invention, the scope of which is defined by the appended claims.