Abstract:
A cable handler link ( 10 ) includes a body portion ( 12 ) having a first wall and two opposed side arms integral with and extending generally perpendicular to the first wall defining a first channel for receiving one or more service lines. The side arms define free ends, arc capable of being deflected and each defines a first engaging formation in the form of a rebate ( 60 ). A closure means ( 14 ) includes an end wall ( 14 ) from which extend two relatively shorter side arms ( 16, 17 ) defining complementary engaging formations including a tenon ( 62 ) for interlocking the closure means to the side arms of the body portion ( 12 ). The side arms deflect towards each other to disengage the closure means from the body portion ( 12 ). The rebate ( 60 ) and tenon ( 62 ) are preferably slightly inwardly tapered and prevent relative transverse movement of the components, which is also the direction in which the link is towed, in use.

Description:
CROSS-REFERENCES 
   This application is a 371 National Phase of International Patent Application Ser. No. PCT/AU2005/001570 filed Oct. 12, 2005 which claims the benefit of priority to Australian Patent Application Serial No. 2004905923 filed Oct. 13, 2004, both of which are incorporated herein by reference in their entirety noting that the current application controls to the extent there is any contradiction with any earlier applications and to which applications we claim priority. 
   FIELD OF THE INVENTION 
   This invention relates to an apparatus for protecting cables, water lines and the like (hereinafter referred to as lines or service lines), particularly, but not exclusively, in underground workings. 
   BACKGROUND OF THE INVENTION 
   During mining operations it is necessary to protect a variety of electrical cables, water hoses and other service lines from damage. One particular area where line protecting apparatus is required, is in the area of coal mining, particularly in longwall coal mining in which a coal cutter traverses back and forth across a coal face depositing coal cut from the coal face into a conveyor disposed behind the coal cutter. In order to operate, the coal cutter requires a supply of water and electricity, which are provided by service lies. The service lines are located in a trough which is typically disposed on the opposite side of the conveyor from the coal cutter and the lines travel up and down the trough as the coal cutter moves up and down the coal face. It should be noted however, that whilst the type of apparatus envisaged by the present invention is particularly suitable for use in handling and protecting service lines for longwall coal mining, other applications of the apparatus are possible. 
   In order to protect such service lines, it is known to enclose, or at least partially enclose them in a protective articulated cable handler formed from a plurality of interconnected links. U.S. Pat. No. 4,988,838 discloses one such cable handler formed from a plurality of interconnected links. Each link has a central web forming a common base for a pair of laterally open channels on respective sides of the central web. For at least some of the links, each channel is formed with a inwardly extending nib so that the entrance to the channel is narrower than the width of the channel. Each link is formed from a plastics material, typically nylon, so that the channel sides are resiliently flexible and a service line can be inserted into a respective one of the channels by deflecting walls of the channel and the nibs apart. After a service line is passed through the channel entrance, the channel sides return back to regain their original position and thus prevent the line from inadvertently moving out of the channel. The links are joined by linking the central web of one link to adjacent links hence such cable handlers are referred to as “centre pull” cable handlers. Centre pull cable handlers also preferred because the water hose is kept separate from the electric cable for safety &amp; reliability reasons. 
   PCT/GB95/00384 discloses a development of the apparatus shown in U.S. Pat. No. 4,988,838 in which the web is located to one side of the link instead of being centrally located, and the channel is approximately twice the depth of the centre pull design. This type of cable handler is referred to as a “side pull” cable handler, as the links are articulated via the side web and are pulled along one side only. 
   One problem which is common to the cable handlers of both U.S. Pat. No. 4,988,838 and PCT/GB95/00384 results from the presence of stones, flints and the like in the trough along which the cable handler runs. These flints and stones are often narrower than the channel entrance and they can enter the channel and may puncture the water hose or electric cable, thus interrupting the supply of power or water to the coat cutter and disrupting production. Further, the type of heavy duty cables used in underground mining are expensive, particularly the electric cables. The cost of replacing any damaged cables, is high, such that in some environments, mining operators will not use cable handlers of the type described in U.S. Pat. No. 4,988,838 because of the potential for damage to the service lies. 
   To avoid this problem twin pull cable handlers have been developed and are currently used at many longwall operations, particularly in the USA, Australia and the UK. In a twin pull cable handler, each link defines a generally rectangular shaped box in which the electric cable and water line are located. The water hose is not kept separate from the electric cable as with the centre pull design. A removable plate or plates are bolted or otherwise fixed to the tops of the side walls of the rectangle, thereby locking the cables in the U shaped link. The base, side walls, and plate are all solid providing all round protection for the electric cable and water line. The links may be linked/pulled from either or both sides, and are typically pulled from both sides, hence the name “twin pull”. However, whilst such a twin pull design provides a high degree of protection for cables, it will be appreciated that it is an extremely lengthy, tedious and time consuming process to install a pair of lines in a twin pull cable handler compared to a centre pull cable handler such as in U.S. Pat. No. 4,988,838 or a side pull cable handler, because of the need to attach a plate to each link in turn. For a typical longwall mine which might require a cable handler which is many metres long, this may take many hours, even days, and will result in loss of operating time. There is also the risk of the bolts, clips or the like securing the plates to the channels, becoming loose and separating from the channel. It will also be appreciated that, because the links have to be articulated to allow the cable to fold back upon itself, as the coal cutter traverses up and down the coal face, however the cable handler is designed, it is impossible to totally enclose the cables In a cable handler which is made of articulated rigid protective elements, as gaps are required between links to allow articulation. 
   International Patent Application publication number WO 03/095797 discloses one attempted solution to this problem. The links of the cable handler disclosed in that publication define a channel having an end wall and flexible side walls for receiving at least one, and typically two service lines. Engaging formations are defined on the free ends of the side walls and a second end wall plate defining engaging formations adapted to engage with the engaging formations of the side wall is provided. Engagement between engaging formations is enabled by flexing of the side walls to securely engage the second end wall between the side arms thus preventing movement of the second end wall relative to the side walls, absent flexure of the side walls. At least one, and preferably both, of the end walls is provided with pivotal formations to enable the chain link to be pivotally connected to a similar link to form a chain. Although, in theory, the design of WO 03/095797 should provide good protection for cables against a the presence of stones, flints and like in the trough, in practice it has been found that the end wall plates are not securely retained in the line of maximum parting force between the side walls in all conditions, and the end wall could possibly disengage from the rest of the link, in use. Further in the design shown in WO 03/095797, the water hose is not kept separate from the electric cable. 
   Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the priority date of each claim of this application. 
   SUMMARY OF THE INVENTION 
   In a first aspect there is provided a link of a chain link for protecting cables, service lines and the like comprising: 
   a body portion having a first wall and two opposed side arms integral with the first end wall extending away from one side of the first wall and defining at least one channel for receiving at least one service line, the side arms having free ends and being capable of being deflected, the end walls defining first engaging formations; and 
   a closure means defining an end wall, the end wall defining complementary engaging formations to the first engaging formations for interlocking the end wall to the first component characterised in that the engaging formations are such the side arms of the body portion are deflected towards each other to disengage the closure means from the body portion. 
   The closure means may comprise an end wall from which extend relatively shorter side arms on which the complementary engaging formations are defined. 
   Typically the engaging formations include a rebate defined in the free end of each side arm and a key or tenon defined at the free end of each relatively shorter side arm. The rebate and key are preferably slightly inwardly tapered. The key and rebate prevent relative transverse movement of the components, which is also the direction in which the link is towed, in use. 
   The engaging formations may also include a channel extending transversely across the width of one of the shorter side arms or the longer side arms and a depending rib extending transversely across the width of the other of the shorter side arms or the side walls. Preferably the channel is defined on the side walls adjacent the rebate. 
   In one preferred embodiment the body portion defines two channels extending from opposite sides of the first wall. In this embodiment, the two channels each define engaging formations for receiving a respective closure means defining shorter side arms on which complementary engaging formations are defined. Both the first wall of the body portion and both end walls of the two closure means typically include linkage means so that the links may be connected in the centre and at both sides. 
   For twin pull or side pull links where the water and electrical cables would ordinarily be carried in the same channel a separator may be provided which snap-fits into the channel to separate the two cables. The separator may have a hour glass like cross-section being narrower at its middle than its top and bottom. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A specific embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings in which: 
       FIG. 1  is a schematic top plan view of a first embodiment of a chain link for a line protecting apparatus embodying the present invention comprising first and second interlocked components; 
       FIG. 2  is a schematic side view of the chain link of  FIG. 1  showing the link holding two cables; 
       FIG. 3  is a schematic top plan view of the chain link of  FIG. 1  with the first and second components separated to illustrate engaging formations on the components, and showing one end only of the first component; 
       FIG. 4  is a schematic side view of the chain link of  FIG. 1  with the first and second components separated to illustrate engaging formations on the components, showing one end only of the first component; 
       FIG. 5  is a schematic top plan view of a second embodiment of a chain link for a line protecting apparatus embodying the present invention; 
       FIG. 6  is a schematic side view of the embodiment of chain link of  FIG. 5  showing the link holding two cables; 
       FIG. 7  is a general assembly of a third embodiment of a chain link for a rifle protecting apparatus, embodying the present invention; 
       FIG. 8  is a perspective view of a fourth embodiment of a chain link for a line protecting apparatus embodying the present invention; 
       FIG. 9  is a side view of a cable separator for use with the fourth embodiment show in  FIG. 8 ; and 
       FIG. 10  is an end view of the cable separator of  FIG. 9 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to the drawings,  FIGS. 1 to 4  show a first embodiment of a line protecting apparatus or chain link  10  which forms one link of an articulated chain. The chain link comprises two parts: a body portion in the form of a generally U-shaped channel element  12 ; and a detachable closure means  14  which defines an end wall  15  from which extend a pair of short side arms  16 ,  17 . The U-shaped channel element  12  includes a first or end wall  18  and two identical opposed side arms or walls  20 ,  22 , integral with the end wall and defining free ends  20   a,    22   a  (best seen in  FIG. 4 ). 
   The body portion  12  is formed from a moulded plastics material such as high viscosity nylon incorporating a steel insert  24  to provide additional strength and to provide linkage means. The side walls  20 ,  22  are not reinforced and are generally flexible. 
   The steel insert  24 , which is not ordinarily visible being largely encased in nylon, but is best seen in  FIG. 1 , comprises two parallel cranked linkage elements. At one end  30 , it defines a through aperture  32  and at the other end  34  defines two parallel arms  36  which define coaxial apertures  38 . The relatively narrower portion  30  of one insert  24  can be inserted between the arms  36  of an adjacent insert and the inserts may be linked together with a bolt or other suitable means passing through the apertures  32  and  38 . 
   The closure means  14  is similar in design to the end wall of the U-shaped channel element  12  in that it is formed from a moulded plastics material, again typically high viscosity nylon incorporating a steel insert  40  of substantially the same shape and design as the insert  22  of the end wall  18 , to provide additional strength and additional linkage means. Thus when the closure means  14  is attached to the channel means, as illustrated in  FIGS. 1 and 2 , a twin pull chain link is defined. The means by which the closure means  14  and the U-shaped channel element  12  are interlocked can be seen more clearly with reference to  FIGS. 3 and 4 . 
   The side walls  20 ,  22  of the channel element extend away from the end wall  18  in a longitudinal direction and define a generally rectangular cross-section transverse to their longitudinal extent. The side walls  20 ,  22  are parallel to one another and symmetrical about a longitudinally extending plane L extending between and parallel to the side walls. Typically they will be about 6 mm deep, although this depth may be varied. A channel  50  is defied in the outer face of each side wall  20 ,  22  adjacent each end  20   a,    22   a.  Since the engagement means defined by the ends of the side walls are identical, one only on sidewall  22  will be described. 
   The channel  50  extends in a transverse direction from one side of the side wall  22  to the other. As is best seen in  FIG. 4 , the channel is defined in a U/J shaped thickened portion  52  defined at the end  22   a  of the arm in which the underside of the arm  22  is thickened to provide an increased depth of material underneath the channel  50 . The base  52  of the channel  50  is typically about 8 mm deep relative to the outer surface of the side wall  20 . This allows for wear of the top and bottom faces of the link, in use. 
   As is best seen in  FIG. 3  (and shown in phantom in  FIG. 4 ), a generally rectangular slot or rebate  60  with slightly tapered walls is defined in the end of the side wall  22 . The rebate extends from tie middle of the side wall of the channel  50 , in the direction of the end wall  18 . The walls taper gently towards each other in the direction of the end wall  18 . 
   Complementary engaging formations which mate with the channel  50  and rebate  60  are defined on the end element  14 . There is preferably zero tolerance/clearance between the inter-engaging formations to ensure a tight fit. 
   In particular, with reference to  FIGS. 3 and 4 , the short side arms  16 ,  17  of the closure means  14  each define a generally rectangular key or tenon element  62  with gently tapering sides which locates in the rebate  60  and prevents movement of the detachable end wall  14  in a transverse direction relative to the U-shaped channel element  12 . 
   As is best seen in  FIG. 4  each short side arm  16 ,  17  also defines an projecting rib  70  which, in use, locates in the channel  52  of the channel element  12  (see  FIG. 2 ). 
   When the two components are interlocked as shown in  FIGS. 1 and 2 , the dovetail-type joint formed by the key  62  and rebate  60  prevents relative movement of the components in a transverse direction T. The channel  50  and rib prevents relative movement in a longitudinal direction L. 
   In order to engage the U-shaped element  12  and end element  14  together, the two elements  12  and  14  are pressed together with the rebate  60  and key  62  aligned. The flexible side walls  20 ,  22  flex towards each other, or may be pushed towards each other to facilitate inter-engagement. In use the link will carry service lines  80  and  90 , for water and electricity, respectively shown in  FIG. 2 . 
   In order to disengage the detachable end wall  14  from the U-shaped channel element  12  the side arms  20 ,  22  of the U-shaped channel element are simply flexed towards each other and the two components  12 ,  14 , separate relatively easily. 
   Advantageously however, because of the design of the engaging means, the engaging means are strongest in the direction of greatest magnitude of force which occurs during use of the chain link that the direction in which the links are pulled along. In use there is little tendency for forces to be applied pushing the side walls  20 ,  22  together hence little likelihood of the detachable end wall accidentally disengaging. 
     FIGS. 5 and 6  show a variant  10  a of the link of  FIGS. 1 to 4 . The link  12  is the same as that of  FIGS. 1 to 4 . The closure means  14   a,  is slightly different from closure  14  as it includes only a single ranked like  40   a  rather than two parallel cranked linkage elements. 
   Although the above describes a link for a twin pull line protector, it will be appreciated that the same principals may be applied to produce side pull, centre pull or triple pull chain links. For a centre pull, side arms will extend out from both sides of the end wall  18 , defining a channel for a water line, and a channel for a cable separated by the end wall, and the ends of those channels may be closed with end walls  14  which do not define linkage means. 
     FIG. 7  illustrates a triple or tri pull link  100 . In this embodiment there is a central wall  101  and two pairs of parallel side arms  102 ,  104  extending away from either side of the central wall  101 . Again a steel insert  24  which is not ordinarily visible being largely encased in nylon which comprises two parallel cranked linkage elements is embedded in the wall  101 . The free ends  102   a  and  104   a  of the side arms are configured the same as the free ends  120   a  and  122   a  of the first and second embodiments and define engaging formations in the form of a channel and rebate. These engage closure means  114   a,    114   b  which are substantially identical to the closure  14   a  of the embodiment of  FIG. 5  although one is a mirror of the other. A single cranked linkage  140   a,    140   b  is embedded in the end wall of each detachable closure  114   a,    114   b  respectively. Using single shear cranked plates keeps the width of the link to an minimum. 
   In a yet further variant a side pull link can be provided by using the body portion  12  of the twin pull described above but with an end wall which does not define any linkage means. 
     FIGS. 8 to 10  illustrate a yet further variant incorporating a cable separator.  FIG. 8  shows a perspective view of a body portion  212  of a twin pull separator of the type shown in  FIGS. 1 and 2  but which differs from the body portion of  FIGS. 1 and 2  in that a notch or cut-out  214  is formed in each outer edges of each side arms  220  and  222  approximately midway between the end wall  218  and the free ends  220   a  and  222   a  of the body portion. A cable separator  230  shown in  FIGS. 9 and 10  is provided. The cable separator has a main body portion  232  which has a height h equal to the vertical gap between the side arms  220  and  222  and relatively higher ends  234  which define protrusions  236  from the body portion and extend above and depend below the main body portion. The protrusions snap or push fit into the notches  214  to secure the cable separator extending transversely across the link. As is best seen in  FIG. 10  in cross-section the cable separator is thicker at its top and bottom and tapers towards its centre, in an hour glass like shape. Typically the link will be 20 mm thick or so at its top and bottom, and as little as 2 mm thick at its middle. In this way the strength and rigidity of the separator and link are maintained whilst keeping the overall width of the link measured from the end wall  218  of the body portion to the end wall of the closure mean (not shown) as small as possible. This provides an arrangement in which the electrical cable and water line can be separated, which is desirable, in a relatively easy operation by flexing the side arms  220  and  222  and inserting the separator. No fiddly nuts or bolts, which may become loose and damage cables are required. The overall width of the link is not increased significantly, indeed, the link is thinner than the tri-pull shown in  FIG. 7 , which is important as there is limited space in the channels in which such chain links run. 
   It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.