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CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. application Ser. No. 14/078,600, filed on Nov. 13, 2013 which claims the benefit of the priority date of U.K. Application No. 1220541.5, filed on Nov. 15, 2012. 
     This application is related to U.S. Pat. No. 8,444,343 which is incorporated herein by reference. 
    
    
     BACKGROUND 
     This invention relates to a bollard and to a method of fixing the bollard to the ground. 
     In supermarkets and retail stores, objects such as freezers refrigerators, shelving and product displays are susceptible to damage due to collisions with items such as shopping trolleys, floor scrubbers and pallet jacks. For example, freezer and refrigerator cases typically include a glass or transparent plastic door for viewing the products inside without opening the door. The glass can be shattered or the plastic scratched, upon impact with shopping trolleys. Since the body of many of these floor fixtures is constructed of lightweight metals or hardened plastic it can be easily dented or cracked by such impacts. Likewise, in industrial locations such as warehouses and manufacturing facilities, both internally and externally, product storage, doorways and equipment are susceptible to damage due to collisions with heavy equipment, such as delivery vehicles and forklifts. 
     A bollard protects objects and fixtures from collisions with all types of vehicles. Bollards are commonly employed inside a store to protect store fixtures and outside a store to protect outdoor structures from collisions, to indicate parking areas, to block vehicle and heavy equipment access to a particular area, and to direct flow of traffic. Bollards can also be used to block vehicular access for security reasons. 
     There are two primary types of bollards; plate-mounted bollards and core-drilled bollards. Plate-mounted bollards conventionally involve a steel plate having three or four bolt holes and a bollard extending perpendicularly from one face of the plate. The plate sits on the floor and bolts are used to fasten the plate, and therefore the bollard, to the floor through the bolt holes. There is no significant disruption to the ground or floor, other than the bolt holes, which are in some instances pre-drilled. On the other hand, core-drilled bollards conventionally require a major disruption to the ground or floor with the creation of a hole two to four feet deep and having a larger diameter than the bollard itself, for example eight inches to two feet, or larger. Concrete is poured into the hole and the bollard is placed in the concrete and held vertically while the concrete cures. In some instances, concrete is also poured into the hollow bollard itself. Installation of a core-drilled bollard is significantly more expensive than with a plate-mounted bollard, and takes significantly more time to complete. However, there are locations where the core-drilled bollard is required due to its ability to absorb larger impacts than the plate-mounted bollard. 
     Plate-mounted bollards are conventionally utilised in areas where impacts are more likely to be less severe, and involve lighter objects, or where no significant impacts are likely and the bollard serves more as a marker. For example, inside a grocery store in front of a freezer case any impact would likely be from a shopping trolley or floor polisher. Such an impact would be considered to be low-energy, or relatively minor. Accordingly, a plate-mounted bollard would be appropriate for this type of installation. However, in a warehouse with heavy equipment, such as delivery vehicles and forklifts, impacts are more likely to be more severe, or high-energy. A vehicle backing up may accidentally collide with a bollard. Accordingly, a core-drilled bollard would be more appropriate in these types of settings. 
     SUMMARY 
     There are a substantial number of installations where a conventional plate-mounted bollard does not provide quite enough impact protection; however, a core-drilled bollard is significantly over-sized for the application. Yet, a core-drilled bollard is installed because the conventional plate-mounted bollard falls short of providing the required protection. Likewise, there are installations where a core-drilled bollard is necessary to provide protection against likely impacts, yet a plate-mounted bollard is installed because they are less expensive or there are logistical problems with drilling four foot deep holes for the core-drilled bollard installation. Other factors may influence the selection of a plate-mounted bollard or a core-drilled bollard. 
     To address this issue, a bollard having an impact absorption mechanism is disclosed in U.S. Pat. No. 7,901,156 B2. This patent discloses a plate-mounted bollard which includes an internal impact absorption mechanism that enables the bollard to absorb impact forces greater than conventional plate-mounted bollards. The bollard makes use of a force transfer process that shifts impact forces to areas better able to resiliently absorb the impact without causing damage to the bollard, the impact absorption mechanism, or the ground in which the bollard is installed. The impact absorption mechanism consists of an internal resilient core rod mounted at its proximal end to a base plate which is fixed to the ground. Impact forces are then transferred through an outer shell to the distal or upper end of the internal resilient core. With energy from the impact force being distributed along the maximum length of the resilient core rod, the rod flexes and the full length of the rod is utilized to absorb the impact energy. 
     Although the bollard of this patent is an effective solution to the provision of a plate-mounted bollard in situation where a core-drilled bollard would normally have been preferred, this bollard is relatively complex and expensive to manufacture and maintain and is not an ideal solution in all circumstances. 
     It is therefore an object of the invention to improve upon the known art. 
     According to a first aspect of the present invention, there is provided a bollard comprising an elongate outer tubular cover, an elongate inner tubular core located within the outer tubular cover, a damper located at a lower end of the inner tubular core, and a washer arranged to locate the damper against the inner tubular core, wherein the outer tubular cover and the inner tubular core are both substantially circular in horizontal cross-section and the outer tubular cover is able to rotate relative to the inner tubular core. 
     According to a second aspect of the present invention, there is provided a method of fixing a bollard to the ground comprising receiving an elongate outer tubular cover, an elongate inner tubular core, a damper, a washer and one or more bolts, passing the or each bolt through the washer, damper and inner tubular core and into the ground, and placing the outer tubular cover over the inner tubular core such that the outer tubular cover is able to rotate relative to the inner tubular core. 
     Owing to the invention, it is possible to provide a bollard that can be used as a plate-mounted bollard that will provide effective collision protection and will also disperse the energy from a low level collision, without any damage to the bollard. The outer cover and the inner core transfer collision energy to the damper within the bollard, which absorbs and disperses the energy of a collision. The bollard is relatively simple to manufacture and install and comprises a small number of relatively straightforward components. The outer tubular cover and the inner tubular core are both substantially circular in horizontal cross-section and the outer tubular cover and the inner tubular core are preferably not connected together. This form of construction of the bollard allows the outer cover to rotate relative to the inner core and this further helps to disperse the energy from a collision, as the rotation of the outer cover will absorb energy prior to any further energy being transmitted to other components within the bollard. 
     In a general aspect, an impact absorption apparatus includes a force transfer member including a base and a sidewall extending from the base, the base including an opening, a shock absorber disposed within the force transfer member and resting on the base, the shock absorber including a through hole, a plate disposed within the force transfer member and resting on the shock absorber, the plate including a through hole, and a fastener that extends through the base opening, the shock absorber through hole, and the plate through hole, the fastener including an end protruding from the base opening, the fastener end configured to secure the force transfer member to a support surface. The force transfer member is configured so that when an impact force is applied to the force transfer member, the force is transferred from force transfer member to the shock absorber. 
     Aspects may include one or more of the following features. 
     A diameter of the opening of the base may be greater than a diameter of the fastener. The force transfer member may be a bumper and the sidewall of the bumper may include an impact deflection portion and one or more flanges extending from the impact deflection portion. The impact deflection portion may have a substantially semi-circular shape. The base may have a substantially semi-circular shape. The shock absorber may have a substantially semi-circular shape. 
     The plate may have a substantially semi-circular shape. Each of the one or more flanges may include a notch causing at least a portion of the flange to be elevated above the support surface. The notch may have a rectangular shape. The notch may have a triangular shape. Each of the one or more flanges may have a substantially triangular shape. The impact absorption apparatus may be configured to evenly distribute a force of impact from the force transfer member into the shock absorber. 
     The shock absorber may include an elastomeric material. The elastomeric material may be a rubber material. The fastener may be a bolt. 
     The sidewall may have an elongate tubular shape with a first cross-sectional diameter. The impact absorption apparatus may include a cover having an elongate tubular shape with a second cross-sectional diameter greater than the first cross-sectional diameter. The sidewall may be disposed within the cover and the cover is able to rotate relative to the sidewall. 
     Advantageously, the outer tubular cover and the inner tubular core are both ground-contacting, with the inner tubular core being closed at the lower end, wherein the washer directly contacts the damper and the damper directly contacts the closed lower end of the inner tubular core. This provides the most effective arrangement of the components, with the outer cover and the inner core both grounded. The inner core is closed at the ground-contacting end with a flat plate which has the washer clamping the damper against the flat plate of the inner core. 
     Ideally, the inner tubular core comprises one or more spacing elements on the external surface thereof. In the preferred embodiment, each spacing element comprises a substantially horizontal ring around the inner tubular core and the inner tubular core comprises two spacing elements on the external surface thereof. The spacing elements provide two main functions, firstly in that they support the rotation of the outer cover around the inner core, during any collision, and secondly they can provide their own shock-absorbing function during a collision. The outer tubular cover can comprise one or more holes, each hole locating a fixing lug. At least one hole is located below a spacing element and the respective fixing lug extends inside the outer tubular cover in a position below the spacing element. The provision of the holes and lugs relative to the spacing elements provides a simple way of retaining the outer cover in position relative to the inner core, without there being any direct connection between these two components. 
     Among other advantages, embodiments more evenly distribute forces of impact into the shock absorber than conventional impact absorbing bollards or rack guards. 
     The bollards and rack guards can receive repeated impacts without needing to be replaced. This is advantageous when compared to conventional bollards and rack guards which can be destroyed by a single impact. 
    
    
     
       DESCRIPTION OF DRAWINGS 
       Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 
         FIGS. 1 and 2  are views of a vertical section through a bollard in the ground, 
         FIG. 3  is a perspective view of an inner core of the bollard, 
         FIG. 4  is a vertical section through the inner core of  FIG. 3 , 
         FIG. 5  is a perspective view of an outer cover of the bollard, 
         FIG. 6  is a perspective view of a damper of the bollard, and 
         FIG. 7  is a perspective view of a washer of the bollard. 
         FIG. 8  is a rear perspective view of an impact absorption apparatus. 
         FIG. 9  is an exploded rear perspective view of the impact absorption apparatus. 
         FIG. 10  is a front perspective view of the impact absorption apparatus. 
     
    
    
     DESCRIPTION 
       FIG. 1  shows a bollard  10  in the ground  28 . The Figure shows a vertical section through the bollard  10 . The bollard  10  comprises an elongate outer tubular cover  12 , an elongate inner tubular core  14  located within the outer tubular cover  12 , a damper  16  located at a lower end of the inner tubular core  14 , and a washer  18  arranged to locate the damper  16  against the inner tubular core  14 . The outer tubular cover  12  and the inner tubular core  14  are both substantially circular in horizontal cross-section and the outer tubular cover  12  is able to rotate relative to the inner tubular core  14 . The outer cover  12  and the inner core  14  are not connected together. The outer cover  12  and the inner core  14  are both ground-contacting. 
     The washer  18  directly contacts the damper  16 . The inner core  14  is closed at the lower end and the damper  16  directly contacts the closed lower end of the inner core  14 . The inner core  14  also comprises two spacing elements  20  on its external surface. Each spacing element  20  comprises a substantially horizontal ring around the inner core  14 . The outer cover  12  has two holes  22 , each hole  22  locating a fixing lug  24 . Each hole  22  is located below a respective spacing element  20  and the respective fixing lug  24  extends inside the outer cover  12  towards the inner core  14  in a position below the respective spacing element  20 . 
     The bollard further comprises three bolts  26 , each bolt  26  passing through the washer  18 , damper  16  and inner core  14  and into the ground  28 . The bolts push together the washer  18 , damper  16  and inner core  14  so that any collision energy is ultimately transferred to the damper  16  which disperses the energy from any collision. The bolts  26  anchor the bollard  10  to the ground  28  and keep the bollard  10  in position. Should any object strike the bollard  10  in a collision then the energy of that collision is directed to the damper  16  through the outer cover  12  and the inner core  14  and the energy is dispersed in this way. 
       FIG. 2  shows a view similar to  FIG. 1 , with an arrow indicating the fact that the outer cover  12  can rotate relative to the inner core  14 . Although the inner core  14  is fixed relative to the ground  28  by the bolts  26 , the outer cover is not actually physically connected to the inner core  14  and is not restrained in any way. There is no connection between these two components of the bollard  10 . This allows the outer cover  12  to rotate. This provides further collision damage protection, as the initial energy from any collision with the bollard  10  will be first dispersed as rotational energy, rotating the outer cover  12 . 
     This collision protection is assisted by the spacing elements  20  that are fixed to the outside of the inner core  14 . The bollard  10  is provided with two spacing elements  20  that are each formed as a ring around the inner core  14 . The spacing elements  20  form part of the inner core  14  and are not fixed to the outer cover  12 . The spacing elements  20  have a horizontal thickness that is slightly smaller than the gap between the outer cover  12  and the inner core  14 . The spacing elements  20  are made from steel and are designed to reduce the surface contact between the outer cover  12  and the inner core  14 , thus reducing the friction between the two parts thereby allowing the outer cover  12  to rotate. 
     The outer cover  12  is provided with two holes  22 , vertically one above the other. These holes  22  receive lugs  24  that can be screwed into position. As can be seen in  FIGS. 1 and 2 , these lugs  24  are flush to the outer surface of the outer cover  12  but extend inwards from the outer cover  12  to touch the inner core  14 . The lugs help to retain the outer cover  12  in position, while not restricting the rotation of the outer cover  12  during a collision. Each lug  24  is below a respective spacing element  20 , and this prevents the removal of the outer cover  12 , once the lugs  24  are in position. The position of a hole  22  (and therefore a lug  24 ) below a respective spacing element  20  also allows the outer cover  12  to move upwards in a collision, to further disperse energy from that collision. So, although the lugs  24  prevent the full removal of the outer cover  12 , they do not stop the outer cover rising upwards during a collision. 
       FIG. 3  shows a perspective view of the inner core  14  of the bollard  10  in an upright position as it would be in use in the bollard  10 . The two spacing elements  20  can be seen on the exterior of the inner core  14 , one of which is towards the upper end of the inner core  14  and the other of which is towards the lower end of the inner core  14 . These spacing elements  20  provide the dual purpose of creating spacing between the inner core  14  and the outer cover  12  when the bollard is in use and providing shock absorption in the event of a collision. 
     A vertical section through the inner core  14  is shown in  FIG. 4 , which shows again the position of the spacing elements  20 . At the lower end  30 , the inner core  14  is closed, so that the essential form of the inner core  14  is a circular cross-section elongate tube that is closed at one end. The closed end  30  is provided with three holes  32  to receive the bolts  26 , when the bollard  10  is constructed in position. The inner core  14  is manufactured from a steel tube with a circular steel plate  30  used to close the one end of the inner core  14 . Holes are drilled into steel plate  30 . 
     As discussed above, the inner core  14  of the bollard  10  is ground-contacting, with the lower end  30  lying horizontally on the ground  28 , with the elongate tubular part of the inner core  14  extending upwards in a vertical direction, as shown in  FIG. 3 . The bolts  26  fasten the inner core  14  in place, passing through the washer  18  and damper  16  and then through the holes  32  in the base plate  30  that forms the lower end of the inner core  14 . The bolts  26  are anchoring the inner core  15  tightly to the ground  28  and ensure that the inner core  14  is fixed in a rigid upright position. 
     The outer cover  12  is shown in a perspective view from above in  FIG. 5 . The outer cover  12  forms the exterior of the bollard  10  and any collision with the bollard  10  will be directly onto the outer cover  12 . As discussed above, the outer cover  12  sits directly on the ground  28  and is not actually connected to any other part of the bollard  10  or indeed to the ground  28 . The outer cover  12  is free to rotate during a collision in order to dissipate as much as energy as possible, without causing damage to any of the components of the bollard  10  or to the ground  28 . 
     As can be seen in this Figure, the outer cover  12  is provided with holes  22  that lie on the same vertical line. These holes  22  are located so that they are underneath respective spacing elements  20  on the exterior of the inner core  14 , when the bollard  10  is assembled in position. The lugs  24  fit into the holes  22  and can be screwed in so that they are flush with the outer surface of the outer cover  12  and will be so positioned that they extend under the respective spacing element  20 . This will prevent unauthorised removal of the outer cover  12  as the lugs  24  will retain the outer cover  12  under the spacing elements  20 . 
     The essential form of the outer cover  12  is a circular cross-section elongate tube that is closed at one end. It is constructed of robust plastics material that will not dent or easily be deformed. The outer cover  12  is a moulding which can be coloured to ensure that is visually stands out as much as possible. At the upper end of the outer cover  12  is a grooved section  34 . 
     The damper  16  is shown in  FIG. 6 , which shows a perspective view of the damper  16 . The damper  16  is provided with three holes  36  that receive the bolts  26  that are used to hold the damper  16  in position. The damper is made from rubber or some other suitable deformable plastics material that will absorb and disperse as much as possible of the energy of any collision with the bollard  10 . The damper  16  is held tightly against the inner core  14  by the washer  18  and the collision energy travels from the outer cover  12  to the inner core  14  to the damper  16 , which disperses the energy of the collision. 
     The washer  18  is shown in perspective view from above in  FIG. 7 . The steel washer  18  is provided with three holes  38  that receive the bolts  26  that are used to hold the washer  18  in position. The washer  18  presses down on the damper  16  as the bolts  26  are tightened to retain the inner core  14  against the ground  28 . This ensures that the inner core  14 , the damper  16  and the washer  18  are all tightly pressed together and held in position once the bollard  10  is assembled. This will mean that in the event of a collision, the energy of the collision will reach the damper  16 , which disperses as much of the energy as possible. 
     The bollard  10  has a very simple construction and is very easy to assemble. The damper  16  and the washer  18  both have a circumference that matches the interior shape of the inner core  14  and are placed in the bottom of the inner core  14 . The inner core  14  can be placed onto the ground  28  and retained in place using the bolts  26 . The outer cover  12  is then placed over the inner core  14  and the lugs  24  are screwed into the holes  22  as far as possible in order to prevent the unauthorised removal of the outer cover  12 . In this way, the bollard  10  is assembled in position. 
     Referring to  FIG. 8  in another embodiment, an impact absorption apparatus  90  utilizes a similar impact absorption mechanism as the inner core of the bollard described above but does not require an outer cover. The impact absorption apparatus  90  includes a bumper  80 , a shock absorber  84  and a free top plate  86 . The bumper  80 , the shock absorber  84 , and the free top plate  86  are held in an assembled position using a fastener such as a bolt  88 . 
     Referring to  FIG. 9 , the impact absorption apparatus  90  of  FIG. 8  is shown in an exploded state to better illustrate the individual elements mentioned in relation to  FIG. 8 . The bumper  80  includes a fixed bottom plate  82  (i.e., a base) and a sidewall including a rounded front portion  81  and two substantially triangular flanges  83  extending from the rounded front portion  81 . 
     The rounded front portion  81  extends from a top end  87  of the bumper  80  to a bottom end  89  of the bumper  80 . In some examples, the rounded front portion  81  has a hollow, semi-circular shape (e.g., the shape of a half of a pipe). In general, at least a portion of the rounded front portion  81  at the bottom end  89  of the bumper  80  rests on the ground (not shown). 
     The rounded front portion  81  has two ends  94  from which the two substantially triangular flanges  83  extend. The flanges  93  also extend from the top end  86  to the bottom end  90  of the bumper  80 . In some examples, a width of each of the flanges  93  increases as the flanges  83  extend from the top end  87  toward the bottom end  89 , resulting in the triangular shape of the flange  93 . In general, at least a portion of each of the flanges  93  at the bottom end  89  of the bumper rests on the ground (not shown). 
     In some examples, each of the flanges  93  includes a notch  92  at the bottom end  89  of the bumper  80 . The notch  92  causes at least a portion of the flange  93  to be elevated from the ground (not shown). In some examples, the notches  92  in the flanges  83  lessen the amount of force that is required to cause the bumper  80  to lean or pivot when it is struck by an object. In some examples, the length and depth of the notches  92  can be adjusted based on an expected force of impact for a given application. If an impact has enough force, the bumper  80  will eventually pivot to the extent that the flanges  83  contact the ground. In this case, the triangular shape of the flanges  93  along with the strength of their material causes the bumper  80  to stop transferring force into the shock absorber  84  and instead act as a hard-stop barrier 
     The fixed bottom plate  82  has a shape which corresponds to an interior of the rounded front portion  81  (e.g., a semi-circle) such that it can be affixed into the rounded front portion  81  at its bottom end  89 , substantially capping the bottom end  89  of the rounded front portion  81 . The fixed bottom plate  82  includes a hole  94  through which the bolt  88  can be inserted. In general, the hole  94  has a diameter which is greater than a diameter of the bolt  88 . The greater diameter provides clearance between the inner edge of the hole  94  and the bolt  88 . The clearance allows the bumper  80  to move with two degrees of freedom about the bolt  88  and ensurEs that the bumper  80  can pivot to a certain extent before the bolt  88  makes contact with the inner edge of the hole  94 . Without the larger diameter hole, the bolt  88  would be easily damaged upon impact. 
     The shock absorber  84  has a shape corresponding to the interior of the rounded front portion  81  (e.g., a semi-circle) such that it can be inserted into the rounded front portion  81 , resting on the fixed bottom plate  82 . In general, the shock absorber  84  is fabricated using an elastomeric material such as rubber. The shock absorber  84  includes a hole  96  through which the bolt  88  can be inserted. The hole  96  has a diameter corresponding to the diameter of the bolt  88 . 
     The free top plate  86  has a shape corresponding to the interior of the rounded front portion  81  (e.g., a semi-circle) such that it can be inserted into the rounded front portion  81 , resting on top of the shock absorber  84 . The free top plate  86  includes a hole  98  through which the bolt  88  can be inserted. In general, the hole  98  has a diameter corresponding to the diameter of the bolt  88 . The free top plate  86  is not directly attached to the bumper  80 . 
     When the bumper  80  is assembled as is shown in  FIG. 8 , the shock absorber  84  is inserted into the front portion  81  of the bumper  80 , resting on the fixed bottom plate  82 . The free top plate  88  is then inserted into the front portion  81  of the bumper  80 , resting on the shock absorber  84 . The bolt  88  is then inserted through the respective holes in the free top plate  86 , the shock absorber  84 , and the fixed bottom plate  82  and into a support surface such as a receiving member anchored in the ground (not shown). The bolt  88  is tightened such that the shock absorber  84  is held snug in place between the free top plate  86  and the fixed bottom plate  82 . 
     In operation, when an object impacts the bumper  80 , the bumper  80  pivots about the bolt  88 , leaning away from the impact until the flanges  83  make contact with the ground. As the bumper  80  leans, the fixed bottom plate  82  leans and presses against the shock absorber  84  which in turn presses against the free top plate  86 . Since the free top plate  86  is held in place by the bolt  88 , the shock absorber  84  compresses between the two plates  82 ,  86 , absorbing the force of the impact. 
     In some examples, the pressure exerted on free top plate  86  by the shock absorber  84  causes the free top plate  86  to lean such that it is maintained in an orientation that is substantially parallel to the fixed bottom plate  82 . By maintaining a substantially parallel orientation between the fixed bottom plate  82  and the free top plate  86 , the force of the impact is more evenly distributed into the shock absorber  84  than would be the case if the two plates  82 ,  86  were angled relative to one another. 
     Once the force of impact on the bumper  80  relents, the resilient material used in the shock absorber  84  returns to its original shape, which in turn returns the bumper  80  to its original position. 
     Referring to  FIG. 11 , a front perspective view of the bollard illustrates the rounded bumper portion  81 . In some examples, the rounded bumper portion  81  causes objects impacting the bumper  80  to glance off of the bumper  80 , thereby reducing the amount of force transferred from the bumper  80  into the shock absorber  84  by the impact. 
     In some examples, the bumper is fabricated using a metallic material such as steel. In such cases the fixed bottom plate is welded into the interior of the front portion of the bumper. In other examples, the bumper is fabricated using a plastic material such as polyvinyl chloride. In such cases, the fixed bottom plate is either attached to the interior of the front portion of the bumper using a high strength epoxy or integrally formed with the front portion of the bumper. 
     In some examples, the notches in the flanges are rectangular in shape. In other examples, the notches are triangular in shape.

Summary:
An impact absorption apparatus includes a force transfer member including a base and a sidewall extending from the base, the base including an opening, a shock absorber disposed within the force transfer member and resting on the base, the shock absorber including a through hole, a plate disposed within the force transfer member and resting on the shock absorber, the plate including a through hole, and a fastener that extends through the base opening, the shock absorber through hole, and the plate through hole, the fastener including an end protruding from the base opening, the fastener end configured to secure the force transfer member to a support surface. The force transfer member is configured so that when an impact force is applied to the force transfer member, the force is transferred from force transfer member to the shock absorber.