Patent Publication Number: US-2020276463-A1

Title: Support post assembly

Description:
BACKGROUND 
     This invention relates to a safety line system for use by a person working at a height above the ground. In particular the invention relates to a support post for a safety line system. 
     When a person is working at height they will typically be connected to a secure mounting by means of a lifeline attached between the mounting and a harness worn by the person. In some circumstances, the secure mounting is in the form of a secure safety line or rail provided across or around a raised area in which the person is working. 
     The person is typically attached to this safety line or rail by means of a lanyard attached at one end to the harness and at the other end to a traveller engaged with and able to slide along the safety line or rail. As such, as the person moves around, the traveller is pulled along the safety rail by the lanyard so as to follow the person around the raised area. 
     The safety line or rail is typically mounted on and supported by a number of support posts at intervals along its length. Support posts may be provided, in particular, at corners of the raised area, so as to provide a means for guiding the safety line or rail smoothly around the corner. The support posts are configured to maintain the safety line or rail in the desired position while allowing the person to move around relative to the safety line or rail without any interference from the support posts. 
     One problem with these systems is that, when a person falls, although some of the energy of the fall may, for example, be absorbed by the lanyard, the relative rigidity of the support posts means that little energy is absorbed by these supports. 
     It is known to provide support posts that have some resilience; however, the amount of energy absorbed or dissipated by the support post is still relatively low compared to the total energy of the fall. 
     It is, therefore, an object of the present invention to provide an improved safety line system and in particular an improved support post for a safety line system which is able to absorb some of the energy from the fall of a person secured to the safety line. 
     SUMMARY OF THE INVENTION 
     The present invention provides a support post assembly for supporting a fall safety line comprising:
         a base;   a support post to which a fall safety line is connectable, the support post having a longitudinal axis;   cooperating curved bearing surfaces disposed between the base and the support post; and   a detent assembly for preventing relative movement of the bearing surfaces below a threshold force, application of a force to the support post by the fall safety line above the threshold force causing the support post to pivot with respect to the base such that the bearing surfaces slide with respect to each other and friction between the bearing surfaces dissipates energy.       

     The fall safety line is preferably connectable to the support post at an end of the support post furthest from the base. The support post may be elongate and extend between first and second ends; the base being connected to the first end of the support post and the fall safety line being connected to the second end of the support post. 
     An axis of rotation about which the support post pivots with respect to the base due to said relative sliding of the bearing surfaces is preferably transverse to the longitudinal axis of the support post. In preferred embodiments the axis of rotation about which the support post pivots with respect to the base due to said relative sliding of the bearing surfaces is substantially perpendicular to the longitudinal axis of the support post. 
     In some embodiments the assembly comprises a single axis of rotation about which the support post pivots with respect to the base due to said relative sliding of the bearing surfaces. The support post is preferably able to pivot in two opposite directions about said axis of rotation depending on the direction of the applied force. 
     The support post may also be rotatable relative to the base about its longitudinal axis. In some embodiments the base comprises a base plate securable to a structure and the support post assembly comprises a coupling member disposed between one of the bearing surfaces and the base plate permitting rotation of the bearing surfaces and support post relative to the base plate about the longitudinal axis of the support post. This permits rotational alignment of the support post relative to the direction of the applied force such that the axis of rotation about which the support post pivots with respect to the base due to said relative sliding of the bearing surfaces extends substantially perpendicularly to the direction of the applied force. 
     In some embodiments the assembly comprises a plurality of axes of rotation about which the support post can pivot with respect to the base due to said relative sliding of the bearing surfaces. The support post assembly may comprise a ball and socket joint between the support post and the base. 
     The support post preferably pivots with respect to the base through an angle of between 45° and 135°. More preferably the support post pivots with respect to the base through an angle of about 90°. 
     In preferred embodiments the support post comprises a first one of the curved bearing surfaces and the base comprises a second one of the curved bearing surfaces, the first bearing surface having a convex curvature and the second bearing surface having a concave curvature. The first bearing surface may be provided by a first bearing plate and the second bearing surface may be provided by a second bearing plate. In some embodiments each of the first and second bearing plates includes an elongate slot extending along a direction of curvature of the bearing plate, and a pin extends through said slots to connect the bearing plates. 
     A support post assembly according to the present invention preferably further comprises a retaining assembly configured to retain the bearing surfaces in contact with each other. The retaining assembly is preferably adjustable to vary the frictional force between the bearing surfaces during relative sliding of the bearing surfaces. The retaining assembly may be configured to apply a clamping force to the bearing surfaces. 
     In a particularly preferred embodiment the retaining assembly and the detent assembly are provided by a single clamping assembly configured to apply a clamping force to the bearing surfaces. In some embodiments the clamping assembly comprises a first clamping member arranged to apply a force to the first bearing plate and a second clamping member arranged to apply a force to the second bearing plate. In embodiments in which each of the first and second bearing plates includes an elongate slot extending along a direction of curvature of the bearing plate and a pin extends through the slots, the clamping assembly may comprise a first clamping member arranged to apply a force to the first bearing plate and a second clamping member arranged to apply a force to the second bearing plate, the first and second clamping members being connected by the pin. 
     The clamping assembly may comprise a spacer disposed between the first and second clamping members, the spacer limiting the minimum distance between the first and second clamping members. In embodiments comprising a pin extending through slots in the bearing plates, the spacer may comprise a tubular member surrounding a shaft of the pin. 
     The detent assembly may comprise a shear pin configured to break at the threshold force. 
     The support post assembly preferably further comprises a mounting member connected to the support post, a fall safety line being engageable with the mounting member. The mounting member is preferably pivotally connected to the support post. 
     In preferred embodiments the support post comprises a shock absorber and the mounting member is connected to the support post by the shock absorber. The shock absorber preferably comprises a resilient element and a force applied to the mounting member by the fall safety line preferably causes a part of the resilient element to be deformed. In some embodiments the shock absorber may comprise a first resilient element on a first side of said pivotal connection and a second resilient element on a second side of said pivotal connection. Movement of the mounting member due to a force applied by the fall safety line preferably causes both of the first and second resilient elements to deform. The or each resilient element may be an elastomeric block. The mounting member may extend through a bore in the or each resilient block. 
     Preferably the shock absorber and the detent assembly are configured such that application of a force to the mounting member by the fall safety line above the threshold force fully deforms the shock absorber and subsequently transmits a force to one of the bearing surfaces to cause the bearing surfaces to slide with respect to each other. 
     The support post preferably pivots with respect to the base between an initial configuration and an activated configuration. In the activated position a part of the support post is preferably seated on a part of the base. 
     The present invention also provides a fall safety line system comprising:
         a support post assembly including a base, a support post, cooperating curved bearing surfaces disposed between the base and the support post, and a detent assembly for preventing relative movement of the bearing surfaces below a threshold force; and   a fall safety line connected to the support post, the application of a force to the support post by the fall safety line above the threshold force causing the support post to pivot with respect to the base such that the bearing surfaces slide with respect to each other and friction between the bearing surfaces dissipates energy.       

     The fall safety line is preferably connected to an end of the support post furthest from the bearing surfaces. The fall safety line preferably extends from the support post in a direction transverse to a longitudinal axis of the support post. In some embodiments the fall safety line will extend from the support post towards a support post of a neighbouring support post assembly. 
     In preferred embodiments the support post comprises a shock absorber, and the fall safety line is attached to a mounting member which is connected to the shock absorber. 
     A support post assembly of the present invention will preferably be attached to a structure on or around which a person is working. The support post assembly may be attached to a structure at a height above the ground. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be further described by way of example only and with reference to the accompanying drawings in which: 
         FIG. 1  is a perspective view of a support post assembly according to a preferred embodiment of the present invention; 
         FIG. 2  is a side view of the support post assembly of  FIG. 1 ; 
         FIG. 3  is a longitudinal, vertical cross sectional view through the support post assembly of  FIG. 1 ; 
         FIG. 4  is a side view of the support post assembly of  FIG. 1  showing the support post in a first partially pivoted configuration; 
         FIG. 5  is a side view of the support post assembly of  FIG. 1  showing the support post in a second partially pivoted configuration; 
         FIG. 6  is a side view of the support post assembly of  FIG. 1  showing the support post in a fully pivoted activated configuration; 
         FIG. 7  is a perspective view of a lower bearing component of the support post assembly of  FIG. 1 ; 
         FIG. 8  is a plan view from above of the lower bearing component of  FIG. 7 ; 
         FIG. 9  is a plan view from below of an upper bearing component of the support post assembly of  FIG. 1  configured to engage with the lower bearing component; 
         FIG. 10  is a longitudinal cross sectional view of the upper bearing component, along the line X-X of  FIG. 9 ; 
         FIG. 11  is a longitudinal cross sectional view of the lower bearing component, along the line XI-XI of  FIG. 8 ; 
         FIG. 12  is a transverse cross sectional view of the upper bearing component, along the line XII-XII of  FIG. 9 ; 
         FIG. 13  is a longitudinal cross sectional view of the lower bearing component, along the line XIII-XIII of  FIG. 8 ; 
         FIG. 14  is a cross sectional view of a clamp assembly for applying a clamping force to the upper and lower bearing components; 
         FIG. 15  is a perspective view of an upper clamp member of the clamp assembly; 
         FIG. 16  is an end view of the upper clamp member of  FIG. 15 ; 
         FIG. 17  is a side view of the upper clamp member of  FIG. 15 ; 
         FIG. 18  is a cross sectional view of the upper clamp member along the line XVIII-XVIII of  FIG. 16 ; 
         FIG. 19  is a perspective view of a lower clamp member of the clamp assembly; 
         FIG. 20  is an end view of the lower clamp member of  FIG. 19 ; 
         FIG. 21  is a side view of the lower clamp member of  FIG. 19 ; 
         FIG. 22  is a cross sectional view of the lower clamp member along the line XXII-XXII of  FIG. 20 ; and 
         FIG. 23  is a perspective view of a spacer of the clamp assembly. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 and 2  show a support post assembly  2  according to a preferred embodiment of the present invention. The support post assembly  2  is configured to support a fall safety line or fall safety rail to which a person will typically be attached by a personal safety line or lanyard and a harness. The support post assembly  2  is preferably mounted on a structure on which the person is working. The support post assembly  2  may form part of a safety line system for a person working at height and, accordingly, the support post assembly  2  may be mounted at a distance above the ground. 
     The support post assembly  2  comprises a base  4 , a support post  6  and a safety line mount  8 . The base  4  is securable to a structure, and the base  4  is preferably located within or proximate the area in which a person is working. The base  4  may be located at a corner of an area in which a person is working at height. The support post  6  is attached to the base  6  at a first end of the post  10  and extends from the base  4  along a longitudinal axis  12  of the support post  6 . The safety line mount  8  is attached to the support post  6  at a second end of the post  14 . 
     The support post  6  is attached to the base  4  such that the support post  6  is moveable with respect to the base  4 . In particular, the connection between the base  4  and the support post  6  permits turning or pivoting movement of the support post  6  with respect to the base  4  about an axis  16  that is substantially perpendicular to the longitudinal axis  12  of the support post  6 . The connection between the support post  6  and the base  4  is configured such that the support post  6  remains connected to the base  4  during this pivoting movement. 
     Advantageously the relative pivoting movement is facilitated by a cooperating pair of bearing surfaces  18 ,  20 ; a first bearing surface  18  being provided on a part of the base  4  and a second bearing surface  20  being provided on a part of the support post  6 . The bearing surfaces  18 ,  20  are curved and may form part of a hinge joint or a ball and socket joint between the support post  6  and the base  4 . 
     In the event of a fall of a person attached to the support post assembly  2  by a safety line or equivalent, a dynamic force is applied to the safety line mount  8 . This in turn applies a lateral force to the second end of the support post  14 . The connection between the support post  6  and the base  4  is configured such that, when the lateral force applied to the support post  6  exceeds a threshold value, the support post  6  turns or pivots relative to the base  4 . Friction between the cooperating bearing surfaces  18 ,  20  dissipates some of the energy of the fall and minimises the peak loads experienced by the falling person. 
       FIGS. 3 to 5  illustrate pivoting or turning of the support post  6  relative to the base  4  in a preferred embodiment of the invention. Preferably the support post  6  pivots about a centre of rotation that lies on the longitudinal axis  12  of the post  6 . The support post  6  is preferably configured to turn through an angle of not more than about 135°, preferably not more than about 120°, and more preferably not more than about 90°. In use the support post  6  may turn through an angle of between 45° and 135°. The support post  6  preferably turns through a maximum angle of 90°. 
     In a typical situation, the base  4  of the support post assembly  2  will be secured to a horizontal surface or platform and the support post  6  will extend vertical upwards from the base  4 , as shown in  FIG. 1 . If sufficient dynamic lateral force is applied to the support post  6  by the safety line mount  8 , the support post  6  will pivot with respect to the base  4  until the longitudinal axis  12  of the post  6  is substantially horizontal, as shown in  FIG. 5 . Further turning of the support post  6  with respect to the base  4  may be prevented by contact between a part of the support post  6  and a part of the base  4 . 
     The structure and configuration of a preferred embodiment of the support post assembly  2  will now be described with particular reference to  FIGS. 3, and 6 to 22 . 
     The base  4  of the support post assembly  2  comprises a base plate  22  including an attachment portion or skirt portion  24  that extends outwardly from a raised portion or platform  26 . Preferably the raised platform  26  is located centrally and the skirt portion  24  extends radially outwards from and surrounds the platform  26 . In use the skirt portion  24  is secured to a part of a structure using suitable fixings. The skirt portion  24  may, therefore, include a plurality of holes  28  for receiving suitable fixings. 
     The base  4  comprises the first or lower bearing surface  18 . In this embodiment, the first bearing surface  18  has a single direction of curvature and is curved along an axis of the bearing surface. 
     The lower bearing surface  18  is provided on a first bearing component  30  connected to the raised portion  26  of the base plate  22 . An embodiment of the first bearing component  30  is shown most clearly in  FIGS. 6 and 7 . In this embodiment the first bearing component  30  comprises a side wall  32  and a seat portion  34  connected to a first end  36  of the side wall  32 . The seat portion  34  includes a first bearing plate  38  extending along an axis between first and second ends  40 . The first bearing plate  38  has a single direction of curvature along the axis and has a concave curvature, such that the first and second ends  40  extend in directions substantially away from the side wall  32 . In particular, the first bearing plate  38  has opposite first and second faces  42 ,  44 ; the curvature of the first face  42  is concave and the curvature of the second face  44  is convex. The first face  42  provides the first bearing surface  18 . The first bearing plate  38  includes an elongate slot  46  extending along the axis of the bearing plate  38 . The slot  46  is configured to receive a clamping assembly  48  discussed further below. 
     Guide walls  50  extend from the concave side of the first bearing plate  38  along edges  52  of the bearing plate  38  between the first and second ends  40 . The guide walls  50  are preferably straight along their length. A top or free edge  54  of each of the guide walls  50  includes a curved recess  56 . This curved recess  56  may be formed by the guide wall  50  having a substantially constant height along its length, such that the curvature of the top edge  54  of the guide wall  50  follows the curvature of the first bearing plate  38 . Each of the first and second ends  40  of the bearing plate  38  includes a depression or indentation  58 . Each of the depressions  58  is disposed centrally between the guide walls  50 . 
     The slot  46  in the first bearing plate  38  extends between the two depressions  58 . A first end  60  of the slot  46  is disposed proximate but spaced from the depression  58  in the first end  40  of the bearing plate  38  and a second end  62  of the slot  46  is disposed proximate but spaced from the depression  58  in the second end  40  of the bearing plate  38 . 
     In this embodiment of the support post assembly  2  the raised portion  26  of the base plate  22  includes a top plate  64  having central recess  66  and an aperture  68 . A coupling member  70  comprises a support plate  72  having a central boss  74  and an aperture  76 , and a side wall  78  extending from an edge of the support plate  72  in an opposite direction to the boss  74 . The coupling member  70  is attached to the raised portion  26  of the base plate  22  such that the support plate  72  is in contact with the top plate  64  and the boss  74  is seated in the recess  66 , with the apertures  68 ,  76  aligned. A fixing, in the form of a bolt  80 , extends through the respective apertures  68 ,  76 . A nut  82  secured to the bolt  80  secures the coupling member  70  to the base plate  22 . 
     The first bearing component  30  is attached to the coupling member  70 . Preferably the attachment is via complementary screw threads  84  on the first bearing component  30  and the coupling member  70 . In this example, the coupling member  70  includes a screw thread  84  on an external surface of the side wall  78  and the first bearing component  30  includes a screw thread  84  on an internal surface of the side wall  32 . 
     The coupling member  70  enables different bearing components and different support posts to be easily connected to the base plate  22 . This may be advantageous if there is a fault or damage to a support post for example. Furthermore, in some circumstances the coupling member  70  and the first bearing component  30 , together with the support post  6  and the safety line mount  8 , may be separated and removed from the base plate  22  when the support post  6  is no longer required. This enables the base plate  22  to remain attached to the structure for subsequent attachment of the support post  6  when it is next required. 
     During use of the support post assembly  2  the coupling member  70  enables the orientation of the bearing surfaces  18 ,  20  and the support post  6  to be varied relative to the base plate  22  by rotation of the coupling member  70  with respect to the base plate  22 . When a dynamic load is applied to the fall safety line, the support post  6  and the first bearing component  30  rotate relative to the base plate  22  such that the axis of the first bearing surface  18  is substantially parallel to the loading direction. This means that the rotational axis of the support post is oriented substantially perpendicular to direction of the applied dynamic load. It will be appreciated that this relative rotation is particularly advantageous when the support post  6  is constrained to pivot about a single axis  16 . 
     It will be appreciated that in other embodiments the first bearing surface  18  and/or the first bearing component  30  may be integral with the base plate  22 . 
     The support post  6  comprises a housing  86 , a shock absorber  88  and the second or upper bearing surface  20 . The second bearing surface  20  is connected to or is provided by the housing  86 . The second bearing surface  20  has a single direction of curvature and is curved along an axis of the bearing surface  20 . 
     The safety line mount  8  is connected to the housing  86  via the shock absorber  88 . This enables some movement of the safety line mount  8  with respect to the housing  86  under certain conditions of lateral loading on the safety line mount  8 . 
     The housing  86  comprises a tubular side wall or sleeve  90 . In this embodiment the sleeve  90  is cylindrical. The housing  86  further comprises an end plate  92  attached to a first end of the sleeve  90  and which substantially closes or blocks the first end of the sleeve  90  so as to define a cavity or internal volume  94  within the sleeve  90 . The end plate  92  includes a central aperture or hole  96  for receiving a part of the safety line mount  8 . A flange  98  extends radially outwards from a second end of the sleeve  90 . The flange  98  extends substantially perpendicularly from the sleeve  90  and extends around the full perimeter of the sleeve  90 . 
     The shock absorber  88  comprises first and second resilient elements  100 ,  102  disposed on either side of a pivot. In this embodiment each of the first and second resilient elements  100 ,  102  is in the form of a resilient block. The resilient blocks  100 ,  102  are disposed on opposite sides of the end plate  92  of the housing  86 ; the aperture  96  in the end plate  92  of the housing  86  providing a pivot as described further below. 
     Each of the resilient blocks  100 ,  102  has a first end surface  104  and an opposite second end surface  106 . The first end surface  104  of the first resilient block  100  is in contact with a first surface  93  of the end plate  92  such that the first resilient block  100  is disposed in the cavity  94  of the housing  86  and extends towards the second bearing surface  20 . The first end surface  104  of the second resilient block  102  is in contact with an opposite second surface  95  of the end plate  92  such that the second resilient block  102  is disposed outside the housing  86  and extends away from the housing  86  and the second bearing surface  20 . 
     Each of the resilient blocks  100 ,  102  includes a bore  108  extending between the respective first and second end surfaces  104 ,  106 . Each of the bores  108  is aligned with the aperture  96  in the end plate  92  of the housing  86 . The bores  108  are preferably cylindrical and have a diameter slightly smaller than a diameter of the aperture  96  in the housing end plate  92 . Each of the bores  108  is preferably disposed centrally within the respective resilient block  100 ,  102 . 
     In this embodiment each of the resilient blocks  100 ,  102  comprises a cylindrical portion  110 , having a constant outer diameter, at a first end of the block, and a frusto-conical portion  112 , having a tapered outer surface, at a second end of the block. Accordingly, the first end surface  104  of the block  100 ,  102  has a larger diameter than the second end surface  106  of the block  100 ,  102 . The outer diameter of the first end of the resilient block  100 ,  102  is preferably the same as or slightly smaller than an internal diameter of the side wall  90  of the housing  86  such that there is no gap or only a minimal gap between an outer surface of the first resilient block  100  at its first end and an internal surface of the housing  86 . 
     The resilient blocks  100 ,  102  are preferably made of an elastomeric material, for example an ethylene propylene rubber. In a preferred embodiment of the invention the resilient blocks  100 ,  102  are made from an ethylene propylene diene monomer (EPDM) rubber, which has good tear and abrasion resistance as well as good weather resistance. 
     A mounting plate  114  is disposed at the second end of the second resilient block  102 . In particular, a first surface of the mounting plate  114  is in contact with the second end surface  106  of the second resilient block  102 . The mounting plate  114  includes a hole  116  that is aligned with the bore  108  in the second resilient block  102 . A diameter of the hole  116  is preferably smaller than the diameter of the bore  108 . The mounting plate  114  may be adhered or otherwise secured to the second end surface  106  of the second resilient block  102 . An outer diameter of the mounting plate  114  is preferably less than the outer diameter of the second end surface  106  of the resilient block  102 . 
     In some embodiments the mounting plate  114  may be provided by an outer housing or cover that surrounds the second resilient element  102 . 
     In this embodiment the upper bearing surface  20  is provided on a second bearing component  118  connected to the flange  98  of the housing  86 . The second bearing component  118  comprises side walls  120 , end walls  122  and a second bearing plate  124  connected to a first end of each of the side walls  120  and end walls  122 . The second bearing component  118  is attached to the flange  98  of the housing  86  at a second end of each of the side walls  120  and end walls  122 . The second bearing plate  124  extends along an axis between first and second ends  126  and has a single direction of curvature along the axis. The second bearing plate  124  has opposite first and second faces  128 ,  130 . The curvature of the first face  128  is concave and the curvature of the second face  130  is convex. The second face  130  provides the second bearing surface  20 . The second bearing plate  124  includes an elongate slot  132  extending along the axis. The slot  132  is configured to receive a part of the clamping assembly  48 . The radius of curvature of the second bearing surface  20  is substantially the same as the radius of curvature of the first bearing surface  18 . 
     The side walls  120  are preferably straight along their length. A distance between respective outer surfaces of the side walls  120  is preferably substantially the same as or slightly smaller than the distance between inner surfaces of the guide walls  50  of the first bearing component  30 . In this way, the second bearing plate  124  is disposed between the guide walls  50  of the first bearing component  30 , such that the second bearing surface  20  is seated on and in contact with the first bearing surface  18 . 
     With the second bearing surface  20  seated on the first bearing surface  18 , the slots  46 ,  132  in the respective bearing plates  38 ,  124  are aligned. Furthermore, the widths of the slots  46 ,  132  are preferably the same. 
     The clamping assembly  48  clamps the first and second bearing plates  38 ,  124  together such that the first and second bearing surfaces  18 ,  20  are in contact. The clamping assembly  48  therefore provides an arrangement for retaining the first and second bearing surfaces  18 ,  20  in contact with each other. Furthermore, the clamping assembly  48  applies a clamping force to the first and second bearing plates  38 ,  124  to prevent relative movement of the bearing surfaces  18 ,  20  below a threshold force. 
     In this embodiment the clamping assembly  48  comprises a clamp pin  134 , a first clamp member  136 , a second clamp member  138  and a spacer  140 , as shown most clearly in  FIGS. 14 to 23 . 
     The first clamp member  136 , shown in  FIGS. 15 to 18 , comprises a main body  142  having opposite first and second faces  144 ,  146 , opposite first and second sides  148  and opposite first and second ends  150 . A bore  152  extends fully through the main body  142  between a first end terminating at the first face  144  and a second end terminating at the second face  146 . The bore  152  is enlarged at the first end to provide a countersink  154 . The bore  152  is also enlarged at the second end for receiving a part of the spacer  140 . A shoulder  156  is therefore disposed between a central portion of the bore  152  and the increased diameter second end region of the bore  152 . 
     The second face  146  of the main body has a convex curvature. The radius of curvature of the second face  146  is substantially the same as the radius of curvature of the first face  128  of the second bearing plate  124 . 
     The second clamp member  138 , shown in  FIGS. 19 to 22 , comprises a main body  158  having opposite first and second faces  160 ,  162 , opposite first and second sides  164  and opposite first and second ends  166 . A bore  168  extends fully through the main body  158  between a first end terminating at the first face  160  and a second end terminating at the second face  162 . The bore  168  is enlarged at the second end for receiving a part of the spacer  140 . A shoulder  170  is therefore disposed between a first region of the bore  168  and an increased diameter second region of the bore  168 . 
     The second face  162  of the main body  158  has a concave curvature. The radius of curvature of the second face  162  is substantially the same as the radius of curvature of the second face  44  of the first bearing plate  38 . 
     The clamp pin  134  includes a shaft  172  and a head  174 . The shaft  172  extends from the head  174  towards a distal end of the shaft  172 . The spacer  140  is in the form of a tubular element having a central longitudinal bore  176  and a circular cross-sectional shape. The spacer  140  extends along its axis between first and second ends  178 ,  180 . A diameter of the bore  176  of the spacer  140  is substantially the same as or slightly larger than a diameter of the shaft  172  of the clamp pin  134 . An external diameter of the spacer  140  is substantially the same as or slightly smaller than the widths of the slots  46 ,  132  in the bearing plates  38 ,  124 . Furthermore, both the second end region of the bore  152  of the first clamp member  136  and the second region of the bore  168  of the second clamp member  138  have diameters that are substantially the same as or slightly larger than the outer diameter of the spacer  140 . 
     The first clamp member  136  is seated on the second bearing plate  124  such that the second face  146  of the main body  142  is in contact with the first face  128  of the second bearing plate  124 . The second clamp member  138  is seated on the first bearing plate  38  such that the second face  162  of the main body  158  is in contact with the second face  44  of the first bearing plate  38 . The spacer  140  is disposed between the first and second clamp members  136 ,  138  and extends through the slots  46 ,  132  in the first and second bearing plates  38 ,  124 . The clamp pin  134  extends through the first clamp member  136 , the bore  176  of the spacer  140  and the second clamp member  138 . The head  174  of the clamp pin  134  is seated in the countersink  154  of the first clamp member  136 . The second clamp member  138  is retained on the distal end of the clamp pin  134  by a nut. 
     The first end  178  of the spacer  140  is seated on the shoulder  156  of the first clamp member  136  and the second end  180  of the spacer  140  is seated on the shoulder  170  of the second clamp member  138 . In this way a length of the tubular spacer  140 , between the first and second ends  178 ,  180 , defines a spacing between the respective second faces  146 ,  162  of the clamp members  136 ,  138 . Accordingly, the length of the spacer  140  defines the clamping force applied to the first and second bearing plates  38 ,  124  by the first and second clamp members  136 ,  138 , and therefore determines the threshold force required to move the bearing surfaces  18 ,  20  with respect to each other. 
     Although in this embodiment the second clamp member  138  is retained on the distal end of the clamp pin  134  by a separate nut, in other embodiments the bore  168  of the second clamp member  138  may be threaded and the distal end of the clamp pin  134  may include complementary screw threads. 
     The clamping force applied to the bearing plates  38 ,  124  determines the magnitude of the threshold force above which the bearing surfaces  18 ,  20  are able to move with respect to each other. The clamping force therefore determines the minimum dynamic load or force that must be applied to the support post  6  to turn or pivot the support post  6  relative to the base  4 . Furthermore, in this embodiment, a greater clamping force increases the frictional force between the opposing bearing surfaces  18 ,  20  which increases the amount of energy dissipated due to movement or sliding of the second bearing surface  20  relative to the first bearing surface  18 . 
     In an initial configuration of the support post assembly  2  the first end  60  of the slot  46  in the first bearing plate  38  and a first end  182  of the slot  132  in the second bearing plate  124  are substantially aligned, and the second end  62  of the slot  46  in the first bearing plate  38  and a second end  184  of the slot  132  in the second bearing plate  124  are substantially aligned. The clamp pin  134  extends through the slots  46 ,  132  at a point substantially midway between the first and second ends  60 ,  182 ,  62 ,  184  of the slots  46 ,  132 . 
     Returning to  FIG. 2 , the safety line mount  8  comprises a mounting member  186  engaged with the support post  6 . The mounting member  186  comprises an elongate shaft  188  that extends between first and second ends  190 ,  192 . A portion of the second end  192  of the shaft  188  is threaded to receive a nut  194 . A head  196  of the mounting member  186  is disposed at the first end  190  of the shaft  188  and the head  196  comprises an aperture  198  for receiving a fall safety line or fall safety rail. In this embodiment the head  196  comprises an annular member integral with the shaft  188 . In use, a fall safety line or fall safety rail is retained by and typically extends through the aperture  198  in the head  196  and extends from the mounting member  186  towards a neighbouring support post assembly  2  or other anchor point. 
     The shaft  188  of the mounting member  186  extends through the hole  116  in the mounting plate  114 , through the bore  108  in the second resilient block  102 , through the aperture  96  in the end plate  92  of the housing  86 , and through the bore  108  in the first resilient block  100 . The first end  190  of the shaft  188 , therefore, protrudes from the mounting plate  114  and extends away from the support post  6  and the second end  192  of the shaft  188  protrudes from the first resilient block  100  and extends towards the second bearing plate  124 . The nut  194  is secured to the threaded portion of the second end of the shaft  188  to retain the mounting member  186  in position relative to the shock absorber  88 . A washer  200  may be disposed between the nut  194  and the first resilient block  100 . 
     In preferred embodiments the hole  116  in the mounting plate  114  is threaded. Further, a portion of the shaft  188  proximate the head  196  is threaded to engage with the threaded mounting plate  114 . This enables the shaft  188  to be secured to the shock absorber  88  with the head  196  at a distance above the mounting plate  114 . 
     The safety line mount  8  is preferably configured such that the fall safety line or fall safety rail, when attached to the mounting member  186 , extends from the support post  6  in a direction substantially perpendicular to the axes of the bearing plates  38 ,  124 . In other words, the fall safety line or fall safety rail, when attached to the mounting member  186 , preferably extends from the support post  6  in a direction substantially parallel to the rotational axis  16  of the support post  6 . 
     The use of the support post assembly  2  will now be described in relation to persons working at height on a platform. A number of support posts  6  are preferably secured around the area of the platform, preferably in or proximate an edge region of the area. The fall safety line or fall safety rail is engaged with the head  196  of the safety line mount  8  of each of the support post assemblies  2 , so that the fall safety line is retained in position with respect to each of the support posts  6 . The fall safety line or fall safety rail applies a static line load to the mounting member  186 . A person or worker is preferably attached to the fall safety line via a traveller which is able to slide along the fall safety line and pass over or around the safety line mounts  8  as the person moves around the work area. 
     If the person falls, the energy of the fall is transmitted via the traveller to the fall safety line. This applies a dynamic force or impulse to one or more of the safety line mounts  8  with which the fall safety line is engaged. In particular, the fall safety line applies a dynamic lateral force to the head  196  of the mounting member  186 . This lateral force is, in turn, transmitted to the support post  6  via the shock absorber  88 . 
     The lateral force applied to the mounting member  186  results in pivoting of the shaft  188  which causes deformation of each of the resilient blocks  100 ,  102  in the support post  6 . In particular, a part of each of the resilient blocks  100 ,  102  is pressed against the fixed, non-rotating end plate  92  of the housing  86 , thereby absorbing some of the energy of the fall in each of the resilient blocks  100 ,  102 . Movement of the shaft  188  is constrained where this passes through the aperture  96  in the end plate  92  of the housing  86  and the mounting member  186  therefore pivots or turns about the aperture  96  in the end plate  92 . The end plate  92  of the housing  86  therefore acts as a pivot plate for the shaft  188  of the mounting member  186 . The pivoting movement of the mounting member  186  causes the mounting plate  114  to compress a portion of the second, upper resilient block  102 , and because the second end  192  of the shaft  188  is constrained within the bore  108  of the first resilient block  100  by the nut  194 , this pivoting movement additionally causes a portion of the first, lower resilient block  100  to be compressed. 
     At the point where the resilient blocks  100 ,  102  have been compressed to their maximum extent by turning of the mounting member  186 , any additional force applied to the safety line mount  8  is transmitted to the housing  86  of the support post  6 . If the magnitude of this additional force is above the threshold force for relative movement of the bearing surfaces  18 ,  20 , the second bearing surface  20  moves with respect to the first bearing surface  18 . In particular, the second bearing surface  20  slides with respect to the first bearing surface  18  in a direction parallel to the axes of the bearing surfaces  18 ,  20 . Because the bearing plates  38 ,  124  are constrained in contact with each other, the curvature of the bearing surfaces  18 ,  20  is such that this sliding movement causes turning or pivoting of the support post  6  relative to the base  4 . 
     The direction of the dynamic force applied to the safety line mount  8  by the falling person may cause the support post  6  and the first bearing component  30  to rotate relative to the base  4  about the longitudinal axis  12  of the support post  6 . Relative rotation between the coupling member  70  and the base plate  22  will occur, if sufficient force is applied, unless and until the axes of the bearing plates  38 ,  124  are aligned with, i.e. parallel to, the direction of the applied force. 
     Furthermore, the arrangement of the bearing components  30 ,  118  and clamping assembly  48  are such that the second bearing surface  20  may slide with respect to the first bearing surface  18  in one of two opposite directions. In a first direction the bearing surfaces  18 ,  20  are able to slide over each other until the clamp pin  134  extends through the slots  46 ,  132  at the first end  60  of the slot  46  in the first bearing plate  38  and the second end  184  of the slot  132  in the second bearing plate  124 . In a second direction the bearing surfaces  18 ,  20  are able to slide over each other until the clamp pin  134  extends through the slots  46 ,  132  at the second end  62  of the slot  46  in the first bearing plate  38  and the first end  182  of the slot  132  in the second bearing plate  124 . In either one of these two positions the support post  6  is pivoted with respect to the base  4  to its full extent given the configuration of the bearing components  30 ,  118 , and the support post assembly  2  is in an activated configuration. 
     The length of the slot  46  in the first bearing plate  38  is preferably such that the slot  46  extends through an angle of between 90° and 100°, and most preferably about 96°. The length of the slot  132  in the second bearing plate  124  is preferably such that the slot  132  extends through an angle of between 100° and 120°, and most preferably about 110°. In this way, the support post  6  rotates through an angle of about 90° between the initial configuration and the activated configuration of the support post assembly  2 . 
     In the activated configuration a part of the side wall  90  of the housing  86  of the support post  6  may contact the first bearing plate  38  to limit further rotation of the support post  6 . In particular the side wall  90  of the housing  86  may be seated in the depression  58  at the first or second end  40  of the first bearing plate  38  in the activated configuration. 
     As the bearing surfaces  18 ,  20  slide over one another the friction between the surfaces  18 ,  20  dissipates some of the energy of the fall. The greater the angle through which the support post  6  rotates with the bearing surfaces  18 ,  20  in contact with each other, the greater the amount of energy that is dissipated due to the friction between the bearing surfaces  18 ,  20 . For a given angle of rotation, the amount of energy dissipated by the bearing surfaces  18 ,  20  may be increased by increasing the length of the bearing surfaces  18 ,  20 , i.e. increasing the radius of curvature of the bearing surfaces  18 ,  20 , by increasing the distance between the centre of rotation and the respective bearing surface  18 ,  20 . 
     During rotation of the support post  6  it is preferable if the head  196  of the mounting member  186 , to which the fall safety line is attached, moves through a minimal distance to minimise the distance added to the fall of the user. 
     It will be appreciated that during use of the support post assembly  2  described above, if a relatively small force is applied to the safety line mount  8  the mounting member  186  is displaced or pivoted relative to the housing  86  of the support post  6  and energy is dissipated by deformation of the resilient members  100 ,  102  of the shock absorber  88 . A smaller dynamic force may be applied to the fall safety line or fall safety rail during, for example, normal movement of the person around the work area. If a relatively larger dynamic force is applied to the safety line mount  8 , indicative of the person falling, after some energy dissipation by the shock absorber  88 , at least a part of the force is transferred to the housing  86  of the support post  6 . If this larger dynamic force exceeds the predetermined threshold force so as to cause the bearing surfaces  18 ,  20  to slide with respect to each other, at least some of the energy of the fall is dissipated due to friction between the opposing bearing surfaces  18 ,  20 . 
     In the above embodiment the bearing surfaces  18 ,  20  were described as being in contact with each other. It will be appreciated that, depending on the materials from which the bearing surfaces  18 ,  20  are made, a layer of lubricant such as grease may be disposed between the opposing bearing surfaces  18 ,  20 . In preferred embodiments the bearing surfaces  18 ,  20  are made of a suitable metal such as stainless steel. In other embodiments one or both of the bearing surfaces  18 ,  20  may be made of a suitable, hard polymeric material. 
     A support post assembly  2  according to the present invention comprises a retaining element or retaining assembly  202  that retains the bearing surfaces  18 ,  20  in contact with each other. The retaining assembly  202  may apply a clamping force to the bearing surfaces  18 ,  20 , or may constrain the bearing surfaces  18 ,  20  in another way such that they remain in contact with each other, such that during relative movement of the bearing surfaces  18 ,  20  energy is dissipated due to friction between the bearing surfaces  18 ,  20 . The support post assembly  2  further comprises a detent assembly  204  that is configured to prevent relative movement of the bearing surfaces  18 ,  20  below a threshold force and to permit relative movement once an applied force exceeds the threshold force. 
     In some embodiments the detent assembly  204  and the retaining assembly  202  may be provided by a single element, unit or assembly. For example, in the above described embodiment of the support post assembly  2 , the clamping assembly  48  provides the function of both the retaining assembly  202  and the detent assembly  204 . In other embodiments the retaining assembly  202  and the detent assembly  204  may be separate and distinct. For example, the detent assembly  204  may be in the form of a shear pin or other frangible connection between the first bearing component  30  and the second bearing component  118 ; the shear pin or frangible connection being configured to break at a predetermined threshold force. The retaining assembly  202  may comprise a clamp, a clip, a channel or a sleeve, for example, that retains the bearing surfaces  18 ,  20  in contact with each other. 
     It is desirable if the support post assembly  2  is configured such that the frictional force between the bearing surfaces  18 ,  20  is adjustable. This allows the threshold force required to move the bearing surfaces  18 ,  20  with respect to each other to be varied, for example to accommodate different arrangements of fall safety line. A taught fall safety line extending between neighbouring support post assemblies  2  may apply a different static line load to the support post  6  compared to a rigid fall safety rail. The additional dynamic load or force then applied to the fall safety line or fall safety rail due to a person falling leads to a different threshold force at which the support post assembly  2  should activate to move the support post  6  from the initial configuration to the activated configuration to dissipate some of the energy of the fall. 
     Although in the above embodiment the support post  6  was constrained to turn or pivot about a single axis due to the curvature of each of the bearing surfaces  18 ,  20  being in single direction, in other embodiments the bearing surfaces may be configured such that the support post  6  can turn about more than one axis relative to the base  4 . In some embodiments it may be desirable for the support post  6  to be able to turn about a plurality of axes. In these embodiments the connection between the support post  6  and the base  4  may comprise a ball and socket joint. In these embodiments the first bearing surface may be provided by a hollow or substantially hemi-spherical socket and the second bearing surface may be provided by a rounded or part-spherical ball-shaped bearing member. 
     In the above embodiment the support post  6  comprises a shock absorber  88  that absorbs or dissipates a first amount of energy when a relatively small dynamic load is applied to the safety line mount  8 . In other embodiments the support post  6  may not include a shock absorber  88  and the safety line mount  8  may be rigidly connected to the housing  86  of the support post  6 . 
     It will be clear to a person of skill in the art that the support post assembly  2  of the present invention does not have to be mounted to a floor or a horizontal surface, but may be mounted on a sloping or vertical surface such as the face of a wall, or an inverted surface such as a ceiling. As such the base  4  may not be located below the support post  6  when the support post assembly  2  is mounted on a supporting surface. 
     The support post assembly of the present invention provides an improved fall safety line support able to absorb some of the energy from a fall of a worker secured to the fall safety line.