Abstract:
The invention provides a clamp and trolley system for moveably attaching a power cable, hose or tube ( 104 ) of a lifting apparatus to a guiding cable or track, the clamp  100 ) comprising: a first clamp component ( 102 ) having a first engagement surface ( 106,116 ) adapted to engage with the power cable, hose or tube ( 104 ); and a second clamp component ( 114 ) having a second engagement surface ( 132,133 ) adapted to engage with the power cable, hose or tube, the second clamp component ( 114 ) being pivotally attachable to the first clamp component and rigidly fastenable to it in a range of relative orientations; wherein the first and second engagement surfaces ( 106,116;132,233 ) are shaped so as to clamp the power cable, hose or tube ( 104 ) between the first ( 102 ) and second ( 114 ) clamp components as the second clamp component ( 124 ) is pivoted towards a more closed orientation.

Description:
FIELD 
       [0001]    The present invention relates to clamping arrangements, trolleys and track systems. In particular, but not exclusively, embodiments of the present invention relate to trolleys and clamping arrangements which couple thereto for carrying power cables, air hoses and the like for systems, such as bridge cranes, and other plant that travels along wires or tracks. Other embodiments of the present invention relate to track systems, which are particularly useful for bridge crane applications, but are not limited thereto. The trolleys and track systems according to the present invention described herein can be used together, but do not need to be. 
       BACKGROUND 
       [0002]    A wide range of industrial and commercial applications involve the lifting and transportation of loads from one location to another with lifting apparatus, such as powered gantry cranes, jib cranes, bridge cranes or overhead cranes. Such cranes typically comprise a hoist for lifting the load, which is accommodated within a trolley or on rollers. The trolley or rollers run along or within a jib, boom or bridge such that the load can be moved along the length of the jib, boom or bridge. 
         [0003]    In the case of overhead or bridge cranes, a pair of spaced apart parallel guides or tracks are situated substantially perpendicular to the bridge and the bridge spans the gap between the parallel guides. The ends of the bridge are typically supported by rollers or trolleys such that the bridge can move along the length of the parallel guides. The parallel guides are typically supported by a floor mounted structure comprising one or more beams and/or columns or by a structure suspended from the roof or overhead structure of a building in which the crane is housed. Hence, loads can be moved anywhere within the reach of the bridge. 
         [0004]    With such powered cranes a continuous energy supply needs to be provided to mobile elements of the crane, such as the hoist moving along the length of the bridge and the trolleys or rollers moving the bridge along the guides. The energy supply may be electrical, pneumatic or hydraulic and the appropriate cabling or tubing needs to be routed through the support structure and crane structure to power the mobile elements. 
         [0005]    Conventionally, the cabling or tubing is routed through the support and/or crane structures using catenary systems comprising wires or tracks along which dedicated trolleys carrying the cable or tubing runs. One problem with known cable or tubing trolleys is that they use a combination of bolts and spacers to attach the cable or tubing to the trolley. Typically the bolts and/or spacers must be completely undone, detached from the trolley and re-coupled to the trolley to enable fitting, which is fiddly and time consuming, particularly when the bolts and/or spacers are dropped during fitting. 
         [0006]    Another problem with conventional cable or tubing trolleys is that they are only suitable for one type of catenary system, namely a wire system, or a track system. Where the trolley is for use with a track system, it is usually for a particular shape of track, such as an I-beam track or a C shaped track. A trolley designed for one shape of track usually cannot be used with another shape of track or does not work as well and can lead to jamming. 
         [0007]    A further problem encountered with at least some known cable or tubing trolleys is that they are only suitable for one type cable, tubing or hose. For example, trolleys suitable for routing electrical cable are typically unsuitable for carrying pneumatic hoses. Some trolleys are even more specific and are only suitable for attaching to a particular shape and gauge of electrical cable. However, cabling for such systems is provided in a wide range or shapes and sizes depending on the application. 
         [0008]    It is a preferred object of the present invention to provide an improved system that addresses or at least ameliorates one or more of the aforementioned problems. 
       SUMMARY OF THE INVENTION 
       [0009]    In a first broad aspect of the invention there is provided a clamp and trolley system for moveably attaching a power cable, hose or tube of a lifting apparatus to a guiding cable or track, the clamp comprising: 
         [0010]    a first clamp component having a first engagement surface adapted to engage with the power cable, hose or tube; and 
         [0011]    a second clamp component having a second engagement surface adapted to engage with the power cable, hose or tube, the second clamp component being pivotally attachable to the first clamp component and rigidly fastenable to it in a range of relative orientations; 
         [0012]    wherein the first and second engagement surfaces are shaped so as to clamp the power cable, hose or tube between the first and second clamp components as the second clamp component is pivoted towards a more closed orientation. 
         [0013]    In one embodiment, the clamp and trolley are mutually detachable, the clamp further comprising a trolley attachment component and the trolley comprising a clamp receiving component, enabling the clamp to be attachable to and removable from the trolley in situ. In one version, the trolley attachment component is integral with the first clamp component. In another version, the trolley attachment component is integral with the second clamp component. 
         [0014]    In one embodiment, the first clamp component comprises a floor the surface of which provides the first engagement surface, and a pair of side walls, and an arm extending from one of the side walls; and the second clamp component comprises a foot pivotally attachable to the arm, the second engagement surface being provided by an underside of the foot. The surface of the floor and/or the underside of the foot may be convex. The surface of the floor and or the underside of the foot may comprise a channel for receiving the power cable or hose at least partially therein. Each side wall of the first clamp component may comprise a flange that bears against an upper surface of the foot. An upper surface of the foot may comprise a concave profile of complementary shape to an underside of the flanges. The second clamp component may be rotatably attached to the arm with a lockable fastener passing through an aperture in the foot and an aperture in the arm. 
         [0015]    In some embodiments, the first and second engagement surfaces may be arranged so that a centre of curvature of the second engagement surface is off-centre with respect to its axis of pivotal rotation. 
         [0016]    In some embodiments, a surface of the second clamp component may be engagable with a surface of the arm of the first clamp component in a plurality of relative positions to provide the fastening in the range of relative orientations referred to in the broad aspect of the invention. This may be achieved with a plurality of radial grooves extending from the aperture in one of the clamp components which engage with a plurality of corresponding radial ridges extending from the aperture in the other clamp component. 
         [0017]    In some embodiments, the trolley attachment component comprises a bearing positioned so as to pivotally suspend the clamp from the trolley. The bearing maybe provided at one end of an elongated member of the first clamp component or the second clamp component, and may be substantially hemispherical to allow pivoting in two dimensions. 
         [0018]    In some embodiments, the first clamp component comprises two hinged parts that open up to facilitate the reception of the power cable, hose or tube. Such embodiments may be particularly suited for receiving a vacuum hose. 
         [0019]    In some embodiments, the second clamp component further comprises a removable snap on fitting to move the second engagement surface closer to the first engagement surface so as to adapt the system to clamp a smaller sized power cable, hose or tube when the snap on fitting is attached. 
         [0020]    In one embodiment, the trolley is adapted to sliding on a slot-shaped track and is generally T-shaped such that arms of the T-shape slide on either side of a slot-shaped track and a trunk of the T-shaped projects downwards through the slot, and the arms are held in perpendicular relation to the slot by one or more removable locking pieces that lock into the trunk and extend upwards into the slot-shaped track, whereby when the locking pieces are removed the trolley may be rotated to a parallel orientation with respect to the slot of the track and removed from the track. There may be two of the locking pieces that are inserted into either side of an aperture on the trunk and lock together on the trunk by cooperating serrated projections. 
         [0021]    In one embodiment, the trolley is adapted to rolling on a guiding cable and may be attached and removed from the cable by loosening and rotating a removable plate from a body of the trolley that houses a wheel for rolling on the cable, thereby creating a gap through which the cable can pass. 
         [0022]    In one embodiment, the trolley is adapted to rolling along an I-beam and comprises: 
         [0023]    a pair of threaded rods or axles mounted to a body containing the clamp receiving component, and 
         [0024]    wheel arrangements threaded on each threaded rod or axle such that a distance between the wheel arrangements can be adjusted by moving them along the threats so as to accommodate different sized I-beams. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0025]      FIG. 1  is a perspective view of a clamping arrangement and a trolley in accordance with embodiments of the present invention; 
           [0026]      FIG. 2A  is a perspective view of a first clamp component of the clamping arrangement shown in  FIG. 1 ; 
           [0027]      FIG. 2B  is a perspective view of another embodiment of the first clamp component; 
           [0028]      FIG. 3  is a perspective view of a clamping foot for the clamping arrangement shown in  FIG. 1 ; 
           [0029]      FIG. 4  is a side elevation of the clamping foot shown in  FIG. 1 ; 
           [0030]      FIG. 5  is an end elevation of the clamping foot shown in  FIG. 1 ; 
           [0031]      FIG. 6  is a perspective view of a body of the trolley shown in  FIG. 1 ; 
           [0032]      FIG. 7  is a perspective view of a removable plate of the trolley shown in  FIG. 1 ; 
           [0033]      FIG. 8  is an end elevation of the trolley shown in  FIG. 1 ; 
           [0034]      FIG. 9  is a perspective view of a trolley for an external track; 
           [0035]      FIG. 10  is a perspective view of a trolley for an internal track; 
           [0036]      FIG. 11  is an underside view of the trolley shown in  FIG. 10 ; 
           [0037]      FIG. 12A  is a perspective view of a first part of a clamping arrangement for a vacuum hose; 
           [0038]      FIG. 12B  is a perspective view of a second part of the clamping arrangement for a vacuum hose; 
           [0039]      FIGS. 13A and 13B  show a variation on the embodiment of the clamp shown in  FIGS. 1 ,  2 ,  3  and  4  with the trolley attachment component differently placed. 
           [0040]      FIG. 14  shows a similar variation on the embodiment shown in  FIG. 12  A. 
           [0041]      FIG. 15  shows an attachment to adapt a clamp for cables, hoses or tubes of smaller cross section. 
           [0042]      FIGS. 16A and 16B  show another embodiment realising the invention with a different arrangement of first and second clamp components. 
           [0043]      FIGS. 17A ,  17 B and  17 C show a trolley adapted to a sliding track in components and in use. 
       
    
    
       [0044]    Skilled addressees will appreciate that elements in the drawings are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the relative dimensions of some of the elements in the drawings may be distorted to help improve understanding of embodiments of the present invention 
       DETAILED DESCRIPTION OF EMBODIMENTS 
       [0045]    Embodiments of the current invention will now be described. In these embodiments, the construction is in plastic, typically injection molded using glass fibre reinforced plastic such as Pa66-gf25, but any other suitable material can be contemplated. 
         [0046]      FIG. 1  illustrates a system comprising a clamping arrangement  100  for clamping different sizes and shapes of power cables, hoses or tubing of lifting apparatus and a trolley  200  for running along cables according to embodiments of the present invention. Embodiments of the clamping arrangement  100  will firstly be described followed by embodiments of the trolley. Further embodiments of the trolley for use with internal and external tracks will then be described. 
         [0047]    Clamping arrangement  100  can be used for clamping a power cable, hose or tubing of a lifting apparatus, such as, but not limited to gantry cranes, jib cranes, bridge cranes or overhead cranes. The clamping arrangement  100  can be used with electrical, pneumatic or hydraulic cabling or tubing having a substantially flat, circular or other cross sectional shape. 
         [0048]    With additional reference to  FIG. 2A , clamping arrangement  100  comprises a first clamp component  102  for engaging with and receiving the power cable or hose  104 . First clamp component  102  comprises a floor  106  and a pair of side walls  108 ,  110  extending substantially perpendicularly upwardly from the floor  106 . An arm  112  extends upwardly at an angle from one of the side walls  108 . In some embodiments, arm  112  is angled at about 36 degrees to the vertical of side wall  108  from which it extends. However, other angles and lengths of arm  112  can be employed. Clamping arrangement  100  comprises a second clamp component in the form of a clamping foot  114  rotatably attachable to the arm  112  for clamping the power cable or hose  104  against the floor  106  of the first clamp component  102 . 
         [0049]    In preferred embodiments, floor  106  of first clamp component  102  is convex and in one embodiment has a radius of curvature of about 95 mm, although other radii of curvature can be used for larger or smaller first clamp components. In some embodiments, as shown in  FIGS. 1 and 2 , floor  106  of the first clamp component comprises a channel  116  at least part way along the length of the floor  106  for receiving power cable or hose  104  at least partially therein. As shown in  FIGS. 1 and 2A , channel  116  has a substantially semi-circular cross section particularly suited for receiving part of a cable having a substantially circular cross section. However, it will be appreciated that such embodiments of the present invention can also clamp power cables or hoses of other cross-sectional shapes. It will also be appreciated that channel  116  can be omitted from floor  106 . 
         [0050]    Each side wall  108 ,  110  of the first clamp component  102  comprises an inwardly extending flange  118  substantially perpendicular to side walls  108 ,  110 . Flanges  118  extend at least partially along the length of side walls  108 ,  110  and in the embodiment shown in  FIGS. 1 and 2A , flanges  118  extend the full length of side walls  108 ,  110 . At least an underside  120  of each flange  118  has a convex profile and in the embodiment shown in  FIGS. 1 and 2A , an upper side  122  of each flange  118  has a convex profile. 
         [0051]    As shown in  FIG. 2A , arm  112  of the first clamp component  102  comprises a tab  124  at the end thereof which is substantially parallel with side walls  108 ,  110 . Tab  124  comprises an aperture  126  located about a centerline of the tab for rotatably coupling clamping foot  114  thereto. A surface  128  of tab  124  comprises a plurality of radial grooves  130  extending from the location of aperture  126 . Grooves  130  are for engaging corresponding ridges of the clamping foot  114  as part of a locking mechanism as described in further detail hereinafter. 
         [0052]    Another embodiment of first clamp component  102  is shown in  FIG. 2B , which comprises many of the features of the first clamp component  102  shown in  FIG. 2A . In this embodiment, an underside  123  of floor  106  comprises one or more recesses  125 , such that at least part of the convex floor  106  comprises hollow portions. Recesses  125  reduce the amount of material used for the first clamp component  102  and therefore the mass and cost. In this embodiment, convex floor  106  has a radius of curvature of about 80 mm, side walls  108 ,  110  of the first clamp component  102  are tapered and at least one of flanges  118  is substantially thicker than the previous embodiment, which is easier to produce. 
         [0053]    With reference to the embodiments shown in  FIGS. 3-5 , second clamp component clamping foot  114  of the clamping arrangement  100  comprises a convex base  132 . An upper side  134  of the base comprises a concave profile of complimentary shape to the undersides  120  of the flanges  118  of the side walls  108 ,  110  of first clamp component  102 . A centre of curvature of the convex base  132  is off-centre with respect to a longitudinal axis of the clamping foot  114  such that the convex base is tapered from one side to the other. As shown in the side elevation in  FIG. 4 , a thickness of the base increases from left to right. This feature assists in the clamping arrangement  100  being able to clamp a range of sizes and shapes of power cable, hose, tube or the like between the clamping foot  114  and floor  106  of the first clamp component  102 . 
         [0054]    According to some embodiments, such as the embodiment shown in  FIG. 3 , at least part of base  132  second clamp component  114  can comprise a channel  133  therein for receiving power cable, tube or hose  104  at least partially therein. In the embodiment shown in  FIG. 3 , channel  133  extends the full length of base  132 . Channel  133  in the base is substantially aligned with channel  116  in floor  106  of first clamp component  102  when channel  116  is provided. 
         [0055]    Clamping foot  114  comprises a body portion  136  extending substantially perpendicularly from base  132 . Clamping foot  114  can comprise one or more webs  138  for additional strength. Clamping foot  114  comprises a barrel  140  having an aperture  142  therethrough. Aperture  142  is substantially coaxial with a central axis of barrel  140 , both of which are substantially perpendicular to body portion  136  of the clamping foot  114 . 
         [0056]    Clamping foot  114  is rotatably attached to arm  112  of the first clamp component  102  with a lockable fastener passing through aperture  142  in barrel  140  of the clamping foot and aperture  126  in arm  112 . Lockable fastener can comprise a bolt, one or more washers and a wing nut  144 , as shown in  FIG. 1 , although other fasteners can be used. In the embodiment shown in  FIG. 3 , barrel  140  comprises a recess  135  for accommodating a hexagonal head of a bolt. 
         [0057]    As shown in  FIGS. 3 and 4 , a surface  146  of barrel  140  comprises a plurality of ridges  148  extending radially from the location of aperture  142  in the barrel of the clamping foot  114 . The plurality of radial ridges  148  in the clamping foot  114  are engaged by or within the plurality of radial grooves  130  in tab  124  of arm  112  of the first clamp component  102 , which aid locking clamping foot  114  in the first clamp component  102  in a plurality of relative positions. 
         [0058]    In alternative embodiments, the grooves  130  can be provided on the surface  146  of barrel  140  of clamping foot  114  and the ridges  148  can be provided on the arm  112  of the first clamp component  102  to achieve the same locking effect. In other alternative embodiments, the grooves and ridges can be arranged in different shapes, such as a semi-circular pattern and/or the grooves and ridges can be of different shapes. 
         [0059]    Clamping foot  114  also comprises a bearing  150  at an opposite end to the base for pivotally suspending the clamping arrangement  100  comprising first clamp component  102  and clamping foot  114  from trolley  200 . Bearing  150  is provided at the end of an elongate member  152  protruding from barrel  140  of the clamping foot. Bearing  150  comprises a substantially hemispherical portion  154  to provide smooth pivoting in the trolley  200  and to minimize jamming during movement of the trolley  200 . 
         [0060]    In accordance with another form of the present invention, trolley  200  for a power cable, hose, tubing or the like of a lifting apparatus is provided. As shown in  FIG. 1 , trolley  200  can be used with the clamping arrangement  100  described herein, but the trolley  200  is not limited to use therewith and can be used with other clamping arrangements or hangers. As shown in the embodiment in  FIG. 1 , trolley  200  comprises a body  202 , a removable plate  204  mountable to the body and at least one wheel or roller  206  rotatably mounted directly or indirectly to the body  202 . Each of these features will now be described in more detail with reference to  FIGS. 6-8   
         [0061]    Referring to  FIG. 6 , body  202  of the trolley  200  comprises a substantially hemispherical or bowl-shaped seat  208  for pivotally accommodating a bearing of a clamping arrangement. Seat  208  is particularly suited to accommodating bearing  150  of the clamping arrangement  100  described above for clamping the power cable or hose  104  of the lifting apparatus. Body  202  comprises a slot  210  to enable placement and removal of the bearing  150  on the seat  208 . Slot  210  allows elongate member  152  of clamping foot  114  to pass therethrough and aperture  212  at the base of seat  208  allows elongate member  152  to protrude therethrough when bearing  150  is accommodated within seat  208 , as shown in  FIG. 1 . 
         [0062]    In this embodiment, body  202  comprises a wall  214  extending substantially perpendicularly from the body. Wall  214  comprises an aperture  216  for receiving a fastener therethrough for rotatably mounting at least one wheel or roller directly or indirectly to the body  202 . 
         [0063]    In this embodiment body  202  also comprises a channel  218  for receiving a removable plate  220 , shown in  FIG. 7 , which is mountable to the body  202 . Channel  218  is curved and is interrupted by slot  210 . Adjacent channel  218  is a recess  222  substantially perpendicular to channel  218  for receiving one or more projections  224  of removable plate  220 . Wall  214  has a substantially circular shape and comprises a curved flange  226  extending substantially perpendicularly from the wall  214 . 
         [0064]    As shown in  FIG. 7 , removable plate  220  comprises a wall  228  having an aperture  230  therethrough and a base portion  232 . Base portion  232  comprises projections  224  for engagement with recess  222  of body  202  of the trolley  200 . Wall  228  has a substantially circular shape and comprises a double flange arrangement  234  extending substantially perpendicularly from the wall  228 . Double flange arrangement  234  is curved and shaped to receive curved flange  226  of body  202 . 
         [0065]      FIG. 8  shows body  202  and removable plate  220  coupled together with a guide wheel  236  held therebetween. Projections  224  engage with recess  222  of body  202  and base portion  232  is received within channel  218 . A fastener passes through aperture  230  in the plate  220 , an aperture in the guide wheel  236  and aperture  216  in the body  202 . Double flange arrangement  234  of the plate  220  receives curved flange  226  of body  202 . A wing nut  238  couples to the fastener to secure the body  202 , plate  220  and guide wheel  236  together. The fastener can be in the form of a bolt comprising a straight pin upon which the guide wheel  236  freely rotates between the body  202  and plate  220 . A steel washer and helical spring can also be added before affixing the wing nut  238 . However, it will be appreciated that other fastener arrangements can be employed. In this embodiment, guide wheel  236  comprises a groove for running along a cable or wire. Hence, trolley  200  is particularly suited to a cable or wire catenary power supply system. 
         [0066]    In use, as exemplified by the embodiment of  FIG. 1  and referring back to  FIGS. 1 and 8 , trolley  200  is attached to a catenary cable by slackening wing nut  238  and slewing removable plate  220  away from body  202  to create a gap through which the catenary cable can pass. Wing nut  238  is then tightened to secure removable plate  220  to body  202  of trolley  200 . Neither wing nut  238  nor removable plate  220  needs to be removed completely, thus avoiding separate parts that can be dropped during fitting. A cable or hose  104  is secured to clamping arrangement  100  by slackening wing nut  144  and swinging clamping foot  114  away from first clamp component  102  about the fastener passing through aperture  142  of barrel  140  and tab  124  of first clamp component  102 . Clamping foot  114  is swung away in the direction of the thicker side of the convex base  132 . Cable or hose  104  is placed on floor  106  of first clamp component  102  and wedged between the floor  106  and convex base  132  as the clamping foot  114  is swung back in the direction of the thinner side of the convex base  132 . Ridges  148  engaging with grooves  130  between the surface  146  of the barrel  142  of the clamping foot  114  and the surface  128  of tab  124  of the first clamp component  102  serve to lock the clamping foot  114  in position in the first clamp component  102  with the cable or hose  104  securely held in position as wing nut  144  is tightened. In this embodiment there are no parts to drop or misplace during clamping of the cable or hose  104 . 
         [0067]    Another embodiment of the trolley is shown  FIG. 9 , which is for use as an external trolley. The trolley  300  comprises a pair of threads  302  on an axle that incorporates body  202 . In some embodiments, a web (not shown) joins the mounting elements to body  202 . Body  202  is substantially similar to body  202  described above in that body  202  comprises seat  208  for pivotally accommodating bearing  150  of a clamping foot  114  of a clamping arrangement as described herein and a slot  210  to enable placement and removal of the bearing  150  on the seat  208 . 
         [0068]    A plate  304  is mounted at respective ends of each of the threaded rods or axles  302 , for example via an aperture  305  comprising an internal thread. One or more wheels or rollers  306  are rotatably mounted to each plate  304  for running along the outside of a solid beam or column, such as a universal beam or column. In the embodiment shown in  FIG. 9 , a pair of rollers  306  is rotatably mounted to each plate  304 . This arrangement is particularly suited for running along an I-beam for a top-running trolley or an underslung trolley. 
         [0069]    Positions of the plates along the length of the threaded rods or axles  302  are adjustable such that the trolley  300  can be adapted for use with different sizes and shapes of beams and columns. One of the threaded rods or axles  302  has a right-handed thread and one has a left-handed thread. Alternatively, different length threaded rods or axles  302  can be attached to body  202  according to the application. 
         [0070]    With reference to  FIGS. 10 and 11 , according to other embodiments, trolley  400  is for use as an internal trolley. Although omitted from the view in  FIG. 10  for the sake of clarity, a plurality of wheels or rollers, such as rollers  306  described above, is rotatably mounted to the body  202  for running along the inside of a hollow track. In the embodiment shown in  FIG. 10 , body  202  comprises seat  208  for pivotally accommodating bearing  150  of a clamping foot  114  of a clamping arrangement as described herein and a slot  210  to enable placement and removal of the bearing  150  on the seat  208 . Body  202  comprises support  402  extending upwardly from body  202  to which wheels or rollers are rotatably mounted by any suitable means.  FIG. 10  shows an embodiment in which support  402  comprises two apertures  404  for mounting two rollers on both sides of the support, thus totalling four rollers. Support  402  is shaped, and apertures  404  are positioned, such that wheels or rollers  306  are mounted centrally above seat  208  and evenly distributed for balance purposes.  FIG. 11  particularly illustrates this showing the central positioning of the support  402  over aperture  212  at the base of seat  208 . 
         [0071]    With reference to  FIGS. 12A and 12B , according to other embodiments, first clamp component  102  comprises two hinged parts  102 A,  102 B, which are shown separately in  FIGS. 12A and 12B . Parts  102 A,  102 B are hinged via a pin (not shown) passing through hinge portions  156 ,  158 , although an alternative hinge mechanism could be used. Each part  102 A,  102 B comprises a respective part  106 A,  106 B of the floor  106  of the first clamp component  102 . Side walls  108 ,  110  comprise respective curved internal walls  108 A,  110 B which form a curved surface, which is particularly suited for receiving a vacuum hose of a lifting apparatus. In alternative embodiments, first clamp component  102  for receiving a vacuum hose is a one-piece component with no hinge. 
         [0072]    Each part  102 A,  102 B comprises an arm  112 A,  112 B extending from a respective side wall  108 ,  110  and each arm  112 A,  112 B comprises a respective tab  124 A,  124 B. Surface  128  of tab  124 A comprises grooves  130  for engaging ridges of clamping foot  114  as described above. Clamping foot  114  as described herein is rotatably attachable to the arms  112 A,  112 B for clamping the vacuum hose against the curved floor  106  and curved internal side walls  108 A,  110 B of the first clamp component. Hence, both sides of first clamp component  102  are securely attached to clamping foot  114 . 
         [0073]    Referring now to  FIGS. 13A and 13B , an alternative first clamping component  102  and second clamp component  114  are shown in comparison to the embodiment described above with reference to  FIGS. 1 ,  2 ,  3  and  4 . The difference is that the elongated member  152  and bearing  150  comprising the trolley attachment component are located on the first clamp component rather than on the second clamp component. It has been found in development that for the shapes shown here, this alternative variation allows the clamped cable to hang from the trolley in the same orientation regardless of the pivoting position of the clamping foot  114  a better pivoting effect for cables. 
         [0074]    Referring now to  FIG. 14 , a similar variation is pictured in relation to the embodiment of  FIG. 12 , where the first clamp component is the composite hinged entity  102 A and  102 B, and the variation of  FIG. 14  comprises the trolley attachment component being on  102 A. 
         [0075]    Referring now to  FIG. 15  a removable snap on fitting  500  is pictured for attachment to the underside of the second clamp component  114  so as to move the second engagement surface  132  closer to the first engagement surface adapting the system to clamp a smaller sized power cable, hose or tube when the snap on fitting is attached. The snap on fitting has four attachment lugs  502 ,  504 ,  506  and  508  of which all but one ( 508 ) comprise projections for securing the snap on fitting. The fitting has an upper surface  510  corresponding to the underside  132  of the first clamp component  114 , and the wall  512  matches the thick end of the tapering foot 
         [0076]    Referring to  FIGS. 16A and 16B , two opposing views are shown of another embodiment realising the invention with a different arrangement of first and second clamp components, particularly suited to clamping round electrical cable of various sizes with the one unit. The first and second clamp components are pivotally attached about axis A through the fastener arrangement  602  previously described, but in this case the first clamp component does not comprise a floor, but rather is disposed on one side and the second clamp component is disposed on the other side. The first clamp component comprises first engagement surfaces  630  which are tapering away from a relatively broad wall  640  shown in  FIG. 16A  to a relatively narrow surface wall  642  shown in  FIG. 16B . The first clamp component also comprises an arcuate channel  606  with the centre of curvature at the axis A and the second clamp component comprises a corresponding arcuate surface  610  with a projection  604  engaging with the channel. The second clamp component also comprises second engagement surface  620  which is shaped to cooperate with the first engagement surface  630  according to the invention. In both diagrams, a void  650  can be seen from both directions showing where the cable passes to be clamped by rotation and fastening as previously described, such that irrespective of diameter the cable is clamped centrally below the bearing  150 . 
         [0077]    Referring now to  FIGS. 17A ,  17 B and  17 C, trolley  700  is adapted to sliding on a slot-shaped track  720  and is generally T-shaped such that arms  704  of the T-shape slide on either side of the slot-shaped track  720  and a trunk  706  of the T-shape projects downwards through the slot, and the arms  704  are held in perpendicular relation to the slot by one or more removable locking pieces  710  that lock into the trunk and extend upwards with a body  712  into the slot-shaped track  720 , whereby when the locking pieces  710  are removed the trolley may be rotated to a parallel orientation with respect to the slot of the track and removed from the track. In this embodiment two of the locking pieces  710  are inserted into either side of aperture  708  on the trunk  706  and lock together on the trunk by cooperating serrated projections  714 . The serrated projections  714  have a slightly curved shape which enables them to fit together in interlocking fashion inside the slot  708 . 
         [0078]    The skilled addressee will appreciate that clamping foot  114  may be rotatably attachable to the different embodiments of first clamp components  102  described herein in a similar manner. It will also be appreciated that different embodiments of first engagement surface  102  may be interchangeable with different embodiments of second engagement surface  114  and the second engagement surface  114  is interchangeable with different trolleys  200 ,  300 ,  400  described herein. Hence, another aspect of the present invention is a system comprising the first clamp components  102 , clamping foot  114  and trolleys  200 ,  300 ,  400  described herein. 
         [0079]    Persons skilled in the art will also appreciate that many variations may be made to the invention without departing from the scope of the invention. 
         [0080]    In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention. Further, any method steps recited in the claims are not necessarily intended to be performed temporally in the sequence written, or to be performed without pause once started, unless the context requires it. 
         [0081]    It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.