Abstract:
A method of installing a height safety system in a fall zone in an underground location is described including the steps of: fitting an anchor point to at least one roof bolt situated above the fall zone; providing a safety line; associating the line with the anchor point; and attaching the line to an operator. Apparatus for use in installing height safety systems are also described.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a height safety systems and to methods of their installation. The invention finds a particular application in installing fall restraint systems in underground mining applications but is not limited to this use. 
       BACKGROUND TO THE INVENTION 
       [0002]    When working at a height there is a risk of injury to workers from falling. In underground mining facilities workers are often required to perform work on power cables, air lines and communications lines and the like which are suspended from the roof of the mine. The workers often have to climb between 1 to 5 metres off the ground to perform this work. Further, a worker will often use whatever objects are in the vicinity to climb up on such as drums, lengths of timber, or by climbing up on mining machinery such as a mine vehicle. 
         [0003]    There is a significant risk of injury posed to workers working at height and there is a need to improve safety of these workers. 
       SUMMARY OF THE INVENTION 
       [0004]    In a first aspect the present invention provides a method of installing a height safety system in a fall zone in an underground location including the steps of: fitting an anchor point to at least one roof bolt situated above the fall zone; providing a safety line; associating the line with the anchor point; and attaching the line to an operator. 
         [0005]    The safety line may be provided in the form of an inertia reel. 
         [0006]    The safety line may be associated with the anchor point by attaching a hook to the anchor point. 
         [0007]    The hook may include a gate which is operable from a distance by way of a pull cord. 
         [0008]    In a second aspect the present invention provides a device for use in installing a safety line including: a hook; a spring loaded gate is associated with the hook; the gate is arranged to be opened from a distance. 
         [0009]    The device may further include a generally elongate handle. 
         [0010]    The handle may be adjustable in length by way of a telescoping action. 
         [0011]    The device may further include a cradle, the cradle being arranged to receive and support an anchor point. 
         [0012]    The cradle may include two upwardly projecting limbs. 
         [0013]    The limbs may include recesses which receive and support the anchor point. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 
           [0015]      FIG. 1  is a perspective view of an embodiment of the invention; 
           [0016]      FIG. 2  shows the hook attachment removed from the device of  FIG. 1 ; 
           [0017]      FIG. 3  shows the device of  FIG. 1  with hook attachment removed; 
           [0018]      FIG. 4  is a top view of  FIG. 3 ; 
           [0019]      FIG. 5  is an enlarged view of detail A of  FIG. 3 ; 
           [0020]      FIG. 6  illustrates how the cradle of the device of  FIG. 3  receives a bow nut; 
           [0021]      FIG. 7  shows the bow nut of  FIG. 6  attached to an exposed end of a roof bolt; 
           [0022]      FIG. 8  is a schematic view of a height safety system installed using the device of  FIG. 1 ; and 
           [0023]      FIG. 8  shows a release hook attachment for use with the device of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0024]    Referring to  FIGS. 1 , a device  10  for use in installing a safety line is shown including a hook  40 . Device  10  further includes an elongate handle  30  which is formed from two members in the form of fibreglass tubes  32 , and  34 . Member  32  is a sliding fit inside member  34  and the two members are secured together by clamp  36 . This arrangement allows the effective length of the handle  30  to be adjusted by releasing clamp  36 , and sliding member  32  out of member  34  to a desired distance and retightening the clamp  36 . 
         [0025]    Referring to  FIG. 2 , hook  40  includes a spring loaded gate  42  and a pull cord  46  is provided which may be pulled to open the gate to allow the gate to be opened from a distance. The pull cord is threaded through the shaft  43  of hook. An eyelet  44  is provided to which a safety line may be attached as will be later described. 
         [0026]    Hook  40  is removably mounted to handle  30  by way of shaft portion  45  being received with a sliding fit into a polythene bush. Referring to  FIGS. 3 to 5 , handle  30  is shown with the hook  40  removed. As best seen in  FIG. 4 , a polythene bush  26  is mounted inside the end of handle and includes a bore  29  which receives shaft portion  4 . 
         [0027]    Still referring to  FIGS. 3 to 5 , the device includes a cradle  20  which is formed from cross member  22  to which are mounted two upstanding limbs  24 . These limbs include recesses  29 . The cradle  20  receives and support an anchor point in the form of a bow nut  16 . 
         [0028]    Use of device  10  to install a height safety system using a mine roof bolt as an attachment point will now be described. The ceilings of mines are typically fitted with a very large number of closely spaced roof bolts. The bolts are inserted into the ceiling of the mine following a tunnelling operation. Nuts are tightened on the bolts which serve to support a roof plate against the roof of the mine to protect it from collapse and to reduce the likelihood of rocks falling from the ceiling of the mine. Approximately 150 mm of thread of the roof bolts is exposed below the roof plate. Roof bolts are typically rated to support a load of 20 tons. 
         [0029]    In a first step, a bow nut  16  is attached to the exposed thread of one of the roof bolts. The roof bolts are located typically some 4 to 5 metres above the floor. In order to install the bow nut  16  from ground level handle  30  is used with the hook  40  removed. 
         [0030]    Referring to  FIG. 6 , the bow nut  16  is inserted into cradle  20 . The length of handle  30  is adjusted as necessary and the handle is used to offer up the nut to an exposed roof bolt end overhead. 
         [0031]    Referring to  FIG. 7 , the handle is rotated to thread the bow nut  16  onto the end of an exposed roof bolt end  17 . Handle  30  is then withdrawn. 
         [0032]    Hook  40  is then inserted into handle  30  as shown in  FIG. 1  and a safety line is attached to eyelet  44  of hook. In a preferred embodiment a safety line is provided in the form of an inertial reel  60 . The inertia reel is attached to eyelet  44  by way of a swivel. Then the free end of the safety line is attached to a harness of a worker. The handle  30  is used to offer up hook  40  to the bow-nut  16 . As the hook is pushed upwards, the inertia reel unwinds. When at the correct height, by pressing the gate  42  of hook  40  against the bow nut  16 , the gate  42  opens inwardly and the hook  40  is thus attached to the bow nut. The gate  42  closes with a return spring. The handle  30  is then withdrawn leaving the hook  40  attached to the bow nut, and the safety line is attached to eyelet  44  of hook  40 . 
         [0033]    An example of the resulting arrangement is shown schematically in  FIG. 8 . A worker is working at height to inspect a bundle of cables  22  that are suspended from a ceiling of an area in an underground mine. Bow nut  16  is attached to one of roof bolts  17 . Hook  40  is attached to bow nut  16 . Safety line inertia reel is attached to eyelet  44  of hook  40 , and the worker is attached to the safety line by way of a harness. The worker is working at height on a ladder. It can be seen that, if the worker were to fall from the ladder for some reason, that the inertia reel would activate and prevent the worker falling to the floor below. 
         [0034]    On completion of the inspection work, the hook  40  is removed from the bow-nut in the following manner. Referring to  FIG. 9 , a hook attachment  70  is shown. The hook attachment includes a hook  72  and a shaft portion  74 . The shaft portion includes a through hole  76  to which is attached a second length of steel cable (not shown) of a similar gauge to the pull cord  46 . The second length of steel cable is selected to be approximately the same length as the height of the work area. The shaft portion  74  is a sliding fit in the bore  29  of bush  28  of handle  30  in a similar manner to the hook  40 . The hook attachment  70  is fitted to handle  30  and the hook  72  is used to catch and retain the looped end of pull cord  46 . When hook portion  70  is attached to pull cord  46  the handle  30  is withdrawn and the second length of cable, which is inserted through hole  76 , hangs down to ground level. Handle  30  is then offered back up to again receive shaft portion  45  of hook  40 . Then, whilst pulling on the second length of steel cable to open gate  42 , the handle is manipulated to free hook  40  from bow nut  16 . The handle  40  is then brought to ground level. 
         [0035]    Finally, hook  40  is again removed from handle  30  and cradle  20  is offered up to receive bow nut to unscrew the bow nut and lower the bow nut back to ground. The height safety system is now fully removed and can be re-used at another location. 
         [0036]    Use of device  10  allows the height safety system to be installed by an operator who is standing at floor level. The roof bolts  17  are rated at 20 tons, and the bow nut is rated at 8 tons. The required strength of a single person fall restraint anchorage point is 1.5 tons according to New South Wales regulations. 
         [0037]    It can be seen that embodiments of the invention provide at least the following advantages:
       Use of pre-existing exposed roof bolts obviated the need for drilling or inserting anchor points thus saving time and components.   System can be installed from floor level and thus there is no risk of falling during installation of the system       
 
         [0040]    Embodiments of the invention have application in other scenarios that do not rely on use of exposed roof bolts. All that is required is a loop or other formation to which the hook  40  can be attached. 
         [0041]    Any reference to prior art contained herein is not to be taken as an admission that the information is common general knowledge, unless otherwise indicated. 
         [0042]    Finally, it is to be appreciated that various alterations or additions may be made to the parts previously described without departing from the spirit or ambit of the present invention.