Field of Invention The present invention relates to a retractable bollard. More particularly, the invention relates to a pneumatically powered retractable bollard for regulating vehicle access wherein a chamber expands under air pressure within a bollard ram, forcing the ram upwards, and wherein the ram can be removed from the bollard assembly without exposing working surfaces.

Background of the Invention

There are many areas that allow vehicle access, for example where people may arrive by vehicle, require parking, or where vehicles may be required to deliver or collect materials. Many such areas also require restrictions to the vehicle access available, for example restricting access to only specific vehicles, only during specific times and/or under specific circumstances.

Retractable bollards can be used to enforce restrictions to vehicle access. One type of typical retractable bollard is a post in the form of a ram that can be raised and lowered as required to prevent or allow vehicle access to an area. Various types of such bollards exist, including rams powered pneumatically, hydraulically, electrically, by screws, winches etc. Pneumatic and hydraulic powered retractable bollards have various advantages over other methods, often requiring fewer parts, comprising a simpler design and being easier to install and maintain.

Many such retractable bollards are based on a design comprising a ram within an outer cylinder. Typically, the ram is sealed radially to the bore of the outer cylinder, which is embedded in the ground with a collar at the top, flush with the ground. Air is supplied under pressure to within the outer cylinder below the ram, and as the ram is sealed radially to the outer cylinder, it is forced upwards by the pressurised air such that it protrudes beyond the ground level and becomes a post to prevent access by vehicles. The depth of the structure embedded in the ground for each bollard is a function of a number of factors. For rams that are flush with the ground while lowered, the depth must be at least the travel of the ram. An additional requirement for many existing bollards with expanding chambers underneath the ram is that the surface of the ram that slides past the seals at the boundary of the expanding chamber must not have structural imperfections, otherwise a seal will not be formed. For such a bollard the entire sliding surface over these seals must remain below ground level when the bollard is fully extended to protect the surface from damage. The depth of such a bollard must therefore be at least twice the travel.

If additional reinforcement is needed, the ram must be even longer, so that a sufficient portion of the ram remains lower than ground level while the ram is fully raised, in order to provide sufficient reinforcement for the ram to hold in the event of an impact, and to minimise damage to the rest of the bollard assembly.

Finally, a portion of the bollard assembly must be located below the ram when fully retracted to at least provide a lower surface for the outer cylinder, deliver air supply and reinforce the rest of the assembly. The total depth required for many existing types of retractable bollards is constrained by these three required depths.

It is advantageous to minimise the depth of a bollard embedment as it is more difficult and expensive to dig deeper and can be more difficult to avoid utilities such as pipe, gas or electric lines. It would therefore be advantageous if an improved retractable bollard was available with a reduced required embedment depth.

Retractable bollards must be periodically maintained. Performing maintenance on a retractable bollard as described above requires removing the ram from the outer cylinder, which exposes the ram and the bore of the outer cylinder, along which the ram seals travel. As surfaces and parts important to the operation of the bollard are exposed on site to the elements and debris, there is a high risk of damage and deterioration, and a high level of care required when performing maintenance, which increases difficulty and costs.

It would be advantageous if the design of such a retractable bollard was revised such that the bollard can be maintained without exposing critical surfaces and parts to contaminants and damage on site. It would be particularly advantageous if the design allowed for critical surfaces and parts to be protected even after removal of the ram from outer cylinder, until they are ready to be serviced in a controlled environment such as a workshop.

Just as it is difficult to remove the ram of existing retractable bollard designs, it is also difficult to reinsert the ram after servicing. It is particularly difficult to reinsert the ram into the outer cylinder while preventing contaminants and damage to critical surfaces and parts. It would be advantageous if an improved retractable bollard was available such that the critical surfaces and parts were protected even during reinstallation of the bollard ram. Collection of water within a bollard assembly can be a significant problem for many existing retractable bollard designs. This problem is exacerbated by many existing retractable bollard designs as, when water enters the assembly, it collects at the bottom of the outer housing. This issue presents additional design challenges to ensure water can be adequately drained or otherwise removed from the assembly, which leads to more complicated parts and often increases the required embedment depth. In many cases, drain lines, pumps or conduits to gravitational discharge points increase the required depth and number of in-road components, leading to higher initial costs, more difficult and expensive maintenance and a more difficult consent process, among other challenges. It would be advantageous if water was better prevented from collecting within the bollard. Furthermore, it would be advantageous if there was an improved way to remove water from the bollard assembly, without increasing the depth of the entire installation.

Many existing retractable bollard designs incorporate a travelling electrical umbilical cord connected to the ram. The electrical umbilical cord allows the ram to perform various functions including lighting, position detection and impact detection. A traveling electrical cord can be inconvenient within a bollard assembly as it requires space and therefore becomes a design consideration, and is also an additional part which can fail. It would be advantageous if the electronic functionality in an improved retractable bollard was achieved without a travelling umbilical cord.

Object of the Invention It is an object of the invention to provide an improved retractable bollard. Alternatively, it is an object of the invention to provide an improved method of raising and lowering a bollard ram.

Alternatively, it is an object of the invention to provide a retractable bollard with improved electronics.

Alternatively, it is an object of the invention to address at least some of the foregoing problems or at least provide the public with a useful choice. Summary of the Invention

According to a first aspect of the invention there is provided a retractable bollard comprising:

an embedded outer housing having an open end and a closed end;

a ram slideably mounted within the outer housing;

means for injecting fluid into, and means for removing fluid from, a chamber within the retractable bollard to move the ram relative to the outer housing between a retracted position and an extended position;

wherein:

the chamber is bounded by one or more sliding surfaces and one or more seals configured to move in sealing relationship relative to the sliding surfaces; and

the ram is able to be completely removed from the outer housing without separating the seals from the sliding surfaces. Preferably, the ram is able to be completely removed from the outer housing without exposing the sliding surfaces.

Preferably, the retractable bollard comprises shielding means configured to shield the sliding surfaces and/or the seals when the ram is completely removed from the outer housing. More preferably, the shielding means shields the sliding surfaces of the chamber and/or the seals from contaminants.

Preferably, the ram comprises a cavity comprising an open end and a closed end, the open end of the cavity facing the closed end of the outer housing, and

the retractable bollard apparatus further comprises: an elongate member extending from the closed end of the outer housing into the cavity of the ram, the elongate member comprising:

a rigid elongate body;

a head mounted on the elongate body and adapted to form the sealed chamber within the cavity of the ram; and

a fluid conduit configured to allow fluid to be injected into or removed from the chamber.

Preferably, the fluid conduit fluidly connects the chamber with an opening in the outer housing.

Preferably, the fluid conduit comprises a hollow cavity extending through the length of the elongate member. Preferably, a bottom end of the elongate member is adapted to be received and retained in position during use by the opening in the outer housing. More preferably, the outer housing may comprise a socket defining the opening and configured to accommodate the bottom end of the elongate member. Preferably, the elongate member is able to be completely removed from the outer housing together with the ram from the open end of the outer housing.

Preferably, the elongate member is able to remain within the ram if the ram is completely removed from the open end of the outer housing.

In preferred embodiments, the shielding means comprises one or more shield members positioned between the elongate member and an inner surface of the cavity of the ram. The shield members may be attached to the inner surface of the ram cavity and configured to slide along the elongate body.

Furthermore, the shielding means may comprise a conduit shield member positioned in or at the end of the fluid conduit and adapted to allow fluid to pass therethrough but prevent passage of contaminants. More preferably, the conduit shield member is an air filter. Preferably, the ram and the outer housing each comprise electrical connectors positioned on the ram and outer housing such that, when the ram is in the fully retracted and/or the fully extended position, the electrical connectors on the ram and outer housing are electrically connected such that, if a voltage is applied to the ram, a detectable change in the electrical characteristics of the ram occurs to indicate that the ram is in the fully retracted and/or full extended position.

Preferably, the ram comprises electronic components able to be powered by a voltage applied to the ram.

Preferably, at least a part of the shielding which shields the locations at which the sliding surfaces are sealed is electrically conductive.

According to a second aspect of the invention there is provided a method of restricting vehicle access to an area using a retractable bollard according to the first aspect of the invention, the method comprising injecting fluid into the chamber in the retractable bollard to extend the ram into a position in which it restricts vehicle access.

According to a third aspect of the invention there is provided a vehicle access restriction system comprising:

at least one retractable bollard apparatus according to the first aspect of the invention; and

at least one fluid supply fluidly connected to the retractable bollard apparatus(es).

Preferably, the system comprises a controller adapted to control the fluid injected or removed from the chamber of each retractable bollard apparatus.

Preferably, the system comprises one or more sensors, the sensors adapted to provide information to the controller about vehicles approaching the retractable bollard.

Preferably, the controller is adapted to control the axial position of the rams based on the information provided by the sensors.

Preferably, the controller is adapted to detect a change in electrical characteristics of the rams and to indicate the position of the rams based on the detected change. According to a fourth aspect of the invention there is provided a method of disassembling a retractable bollard apparatus according to the first aspect of the invention, comprising: adjusting the retractable bollard apparatus such that it is in a fully retracted configuration;

removing components, if any, of the retractable bollard apparatus which, during use, limit the fully extended position of the ram;

completely removing the ram from the open end of the outer housing;

wherein, during the step of completely removing the ram, the seals are not separated from the sliding surfaces.

According to a fifth aspect of the invention there is provided a retractable bollard apparatus comprising:

an embedded outer housing having an open end and a closed end;

a ram slideably mounted within the outer housing;

means for injecting fluid into, and means for removing fluid from, a sealed chamber within the retractable bollard to move the ram relative to the outer housing between a retracted position and an extended position;

wherein:

the ram is able to be removed from the outer housing while maintaining a volume within the chamber which is less than or equal to the volume of the chamber when the retractable bollard apparatus is in a fully extended configuration.

According to a sixth aspect of the invention there is provided a method of disassembling a retractable bollard apparatus according to the fifth aspect of the invention, comprising: adjusting the retractable bollard apparatus such that it is in a fully retracted configuration;

removing components, if any, of the retractable bollard apparatus which, during use, limit the fully extended position of the ram;

removing the ram from the open end of the outer housing;

wherein, during the step of removing the ram, the volume within the chamber is less than or equal to the volume of the chamber when the retractable bollard apparatus is in a fully extended configuration.

Preferably, the method according to the fourth or sixth aspect comprises, during removal of the ram, limiting the volume of fluid allowed to flow into the chamber. Preferably, the method according to the fourth or sixth aspect comprises, during removal of the ram, applying negative pressure to the chamber within the apparatus. More preferably, the method according to the fourth or sixth aspect comprises, during removal of the ram, applying negative pressure to the chamber inside the ram.

Preferably, the method according to the fourth or sixth aspect comprises removing the elongate member with the ram.

According to another aspect of the invention, there is provided a retractable bollard apparatus comprising:

an embedded outer housing having an open end and a closed end;

a ram slideably mounted within the outer housing;

means for adjusting the axial position of the ram between a fully retracted and fully extended position; and

means for applying a voltage between the ram and the outer housing;

wherein the ram and outer housing each comprise electrical connectors positioned on the ram and outer housing such that, when the ram is in the fully retracted and/or the fully extended position, the electrical connectors on the ram and outer housing are electrically connected such that a detectable change in the electrical characteristics of the ram occurs to indicate that the ram is in the fully retracted and/or full extended position. Preferably, the apparatus comprises means for detecting the electrical connection between the ram and outer housing to detect that the ram is in the fully retracted and/or fully extended position.

Preferably, the ram comprises electronic circuitry powered by the voltage applied between the ram and the outer housing.

According to another aspect of the invention, there is provided a retractable bollard apparatus comprising:

an embedded outer housing having an open end and a closed end;

a ram slideably mounted within the outer housing, the ram having a cavity comprising an open end and a closed end, the open end of the cavity facing the closed end of the outer housing;

an elongate member extending from the closed end of the outer housing into the cavity of the ram, the elongate member comprising:

a rigid elongate body;

a head adapted to form a sealed chamber within the cavity of the ram; and a fluid conduit configured to allow fluid to be injected into or removed from the chamber to adjust the axial position of the ram relative to the outer housing.

Further aspects of the invention, which should be considered in all its novel aspects, will become apparent to those skilled in the art upon reading of the following description which provides at least one example of a practical application of the invention.

Brief Description of the Drawings One or more embodiments of the invention will be described below by way of example only, and without intending to be limiting, with reference to the following drawings, in which: is a cross section view illustration of a retractable bollard apparatus according to an embodiment of the invention in a fully retracted configuration; is a cross section view illustration of the retractable bollard apparatus shown in Figure 1 in a fully extended configuration; and is a cross section view illustration of the retractable bollard apparatus shown in Figure 1 in a partly disassembled configuration.

Detailed Description of Preferred Embodiments of the Invention

In a preferred embodiment, the invention comprises a retractable bollard embedded in the ground comprising a cylindrical ram within a cylindrical outer housing that can be extended above the ground surface to restrict vehicle access to an area. The ram comprises an inner cylindrical cavity extending upwards through a portion of the length of the ram and is open at the ram's lower end. A rigid elongate member extends upwards into the inner cavity from the bottom of the outer housing and comprises a head and fluid conduit. The head forms a radial seal with the cylindrical surface of the inner cavity to form a sealed chamber bounded by the head, the cylindrical surface of the inner cavity and the innermost face of the cavity. Fluid is injected into the chamber via the fluid conduit to force a change in volume of the chamber. As the ram is free to move axially, a change in volume of the chamber causes the ram to extend or retract such that the height of the ram above the ground can be adjusted to allow or restrict vehicle access. The ram and elongate member can be removed from the outer housing without separating, which prevents exposure of the internal components because the seals do not become separated from the moving surfaces to which they seal, and they remain shielded from the elements and

contamination. Fully Retracted Configuration

Figure 1 shows a cross section view of bollard 100 according to an embodiment of the invention, in its fully retracted configuration. Outer housing 10 is embedded downward into the ground and contains a ram 20. In the embodiment shown in Figure 1 , the housing and ram are cylindrical but in other embodiments they may take other forms. The outer housing has an open upper end to which a collar 30 is mounted. In the fully retracted configuration the upper end of ram 20, the upper end of collar 30 and the ground surface 5 are all at substantially the same vertical position. Collar 30 comprises seals 31a and 31 b, which seal against the outer cylindrical surface of the ram 20, facilitated by collar 30 having a similar but at least the same internal diameter to the outer diameter of ram 20.

At the bottom of outer housing 10 is base plate 11 , on which cylindrical base stop 12 is mounted within outer housing 10 such that in the fully retracted configuration, the ram 20 is able to rest on, or be in contact with, stop 12. Mounted centrally within stop 12 is socket 13. At the lower end of ram 20 is a ram support collar 21 which is slideably engaged with the internal surface of outer housing 10. Inserted into an upper entrance 131 of socket 13 is injector 40, an elongate member comprising a rigid elongate body 41 with injector passage 411 , extending upwards into a cylindrical ram cavity 22 within the ram 20 and opening at the ram's lower end. At its upper end, injector 40 comprises head 42, which seals to the cylindrical wall of ram cavity 22 with seals 43a and 43b to form chamber 24 between head 42 and the upper end of ram cavity 22. Head 42 comprises an internal head passage 421 allowing fluid communication between injector passage 41 1 and chamber 24. The axis of ram 20 is therefore restrained radially by the outer housing 10, collar 30 and fluid injector 40; however it is able to move axially relative to the outer housing 10, collar 30 and fluid injector 40 to at least some extent.

Socket 13 comprises an internal socket passage 132 to fluidly connect upper entrance 131 of socket 13 with a side entrance 133 through which fluid is supplied. Fluid is therefore able to be supplied to side entrance 133 and thus to chamber 24 via injector passage 411.

Fluid can be injected into chamber 24. Sufficient build-up of fluid pressure in the chamber 24 causes the vertical position of the ram 20 to rise relative to the head 42 and the volume of chamber 24 to increase. Likewise, fluid can be removed from, or allowed to flow out of the chamber 24 in order to reduce the fluid pressure in the chamber, in which case the weight of the ram, or a vacuum created in chamber 24 causes the ram to lower and the volume of chamber 24 to decrease. This allows the ram 20 to be extended and retracted to restrict or allow vehicle access over the ground above it.

In some embodiments, fluid may be removed from the chamber by allowing it to escape to another chamber or reservoir within or in fluid communication with the bollard apparatus. In other embodiments, particularly where the fluid is air, it may be allowed to escape to the surrounding atmosphere. There may be a means for the fluid to escape directly from the chamber, or it may flow back partly through a series of components through which it travelled before reaching the chamber. Suitable means to control the path the fluid takes will be apparent to those skilled in the art, for example one or more one way valves oriented to allow fluid to escape.

In other embodiments, the fluid may be actively removed from the chamber, for example with the use of a pump, which may be the same pump that originally caused the fluid to flow to the chamber operating to pump fluid in the reverse direction.

In some embodiments, the fluid may be pumped into a reservoir maintained at a pressure high enough to force expansion of the bollard (not shown in the Figures), and then the fluid can be provided to the chamber when the ram is to be extended, and allowed to escape when the ram is to be retracted, as required. Preferably, the fluid is air. In alternative embodiments within the scope of the invention, the fluid may be another suitable fluid, for example hydraulic fluid.

Extended Configuration

Figure 2 shows a cross section view of the bollard 100 shown in Figure 1 in its fully extended configuration. In this configuration fluid has been injected into the chamber 24 in order to increase the volume of chamber 24 and extend the ram to the highest allowable position.

Fixed to the outer cylindrical wall of ram 20 is stop ring 25, located part way up the ram above ram support collar 21. The location of stop ring 25 corresponds to the maximum extension of the ram 20. At the maximum extension of ram 20, stop ring 25 comes into contact with the lower surface of collar 30, which has an internal diameter smaller than the outer housing 10, preventing the ram extending any further out of the housing 10.

Depth

Since preferred embodiments comprise a ram with an expanding chamber within the ram, the surface of the sealed chamber that slides over the fluid-tight seals is not on the external surface of the bollard, where it would be exposed to damage from the external above ground environment, as is the case with prior art bollards. Bollards according to some embodiments of the invention are therefore not subject to the same minimum depth requirements, in order to ensure that the sliding surfaces remain below the ground level, as are conventional bollards.

Bollards according to preferred embodiments therefore may have a depth limited by only the length of travel, the length of the ram required to be left beneath the ground surface for reinforcement purposes, and the depth of the parts of the bollard below the ram such as stops, reinforcement and fluid supply means. This may enable a bollard apparatus to have a reduced depth compared to prior art bollards, which makes installation and maintenance easier.

Many existing bollard designs require extensive drainage in the base to ensure water does not build up in the lower portions of the bollard. As the pressurised chamber in preferred embodiments of the invention is located within the ram, the bottom of the outer housing can be ventilated by means of a conduit in fluid connection with the ambient air. As the ram extends and retracts, ambient air may be drawn into the outer housing, and then as the ram retracts, the ram may force air and water that may have collected underneath it in the outer housing to be expelled through the ambient air conduit. This causes the air in the lower part of the outer housing (i.e. the chamber formed underneath the ram) to be recycled every time the ram extends and retracts, helping to remove humid air and reduce moisture accumulation. This reduces the need for drainage under the bollard, meaning less excavation is required below the bollard, making the bollard cheaper and easier to install.

Collar and Collar Seals

In a preferred embodiment, the collar 30 is mounted to the top of outer housing 10 and has a substantially flat surface at substantially the same level as the ground surface 5. In its retracted configuration the uppermost surface of ram 20 is also substantially at the same level as the ground surface 5 so that vehicles can safely pass unrestricted over the bollard 100.

In a preferred embodiment collar 30 may comprise a top collar 32, thrust bearing collar 33 and retaining collar 34.

Retaining collar 34 in some preferred embodiments comprises a circular groove into which the top edge of the outer housing can be received, and may include fasteners to secure the two together. In other embodiments there may be other components between the collar 30 and the outer housing 10.

Top collar 32 has an internal shoulder extending around its internal circumference such that an upper collar seal 31a can be retained in the shoulder against the upper face of thrust bearing collar 33. Retaining collar 34 has an internal shoulder extending around its internal circumference such that a lower collar seal 31b can be retained in the shoulder against the lower face of thrust bearing collar 33.

Collar 30 is fastened to collar bolts 35 with nuts 351. Preferably collar bolts 35 are embedded fixedly in the ground and distributed radially such that they extend upwards through collar 30, which is secured with nuts 351 , which in this embodiment have countersunk heads corresponding to countersinks in the holes through which the bolts extend.

Upper collar seal 31a has a smaller internal diameter than the collar 30 such that it forms a seal with ram 20 yet leaves clearance between the ram and collars. Lower collar seal 31 b also has a smaller internal diameter than the collar 30 to form a seal with the ram 20 yet allow for clearance between the ram and collars.

Upper collar seal 31 a and lower collar seal 31 b seal against the outer surface of the ram 20 to prevent, or reduce the amount of, unwanted liquid or material such as water, dirt or the like from entering into the space between the outer surface of the ram 20 and the inner surface of the outer housing 10.

Upper collar seal 31 a is the bollard assembly's most external barrier to moisture and dust, however being located near the road surface it is more vulnerable to degradation. Lower collar seal 31 b may be less vulnerable being deeper and protected by upper collar seal 31a, and may therefore be better suited to maintain its integrity, which may become important if upper collar seal 31 a is degraded and allows entry of contaminants. Upper collar seal 31a and lower collar seal 31 b may be formed from seals that are oriented opposite to each other and are individually better suited for wiping the sides of the ram depending on its direction of movement, preventing build-up of contaminants between the seals.

In some embodiments there may be any number of seals, and the seals may not be the type able to be energised and instead be any suitable type of seal, for example O-rings or similar, able to prevent substantial transfer of contaminants past the location of the seal, and suitable for dynamic application.

Base Plate, Lower Stops, Socket and Hose

In preferred embodiments, at the bottom of outer housing 10 is a base plate 11 which allows for a substantially flat and solid lower surface of the bollard 100 on which components can be mounted. The base plate 1 1 has a groove shaped to receive the lower end of the outer housing 0. In some embodiments the base plate 11 may comprise holes through which screws may be used to fasten the base plate to the outer housing or other components. In preferred embodiments, mounted on the base plate 11 within the outer housing 10 is stop 12. Stop 12 is cylindrical and provides a surface on which the lower end of the ram 24 may rest in its fully retracted position. Stop 12 may comprise base packing 121 directly on the base plate 11 , resilient stop plate 122 mounted on top of the base packing 121 , and metallic base plate 123 mounted upon the resilient stop plate 122.

Some or all of stop 12 may in some embodiments comprise any number of parts, for example any number of parts equispaced about the axis of the outer cylinder 10 and ram 20, or any number of parts stacked on top of each other.

Resilient stop plate 122 is preferably formed from a rubber material or a similar material to provide a degree of shock absorption to the rest of the bollard 100 upon impact from or on the ram 20. The inner shape of base packing 121 may be formed in a shape matching the outer shape of socket 13, however in some embodiments the socket 13 may not be in contact with the stop 12, or in contact with only part of it.

In preferred embodiments socket 13 receives fluid from a fluid supply hose 134 through side entrance 133 and directs it to upper entrance 31 via socket passage 132. The shape of upper entrance 131 in the preferred embodiments has a chamfer or countersink to allow for easy insertion of the elongate member 41 into the upper entrance 131 , and has an internal diameter to match the outer diameter of elongate member 41. In the preferred embodiment there is an internal shoulder where socket passage 132 meets upper entrance 131. This shoulder provides a firm surface for the lower end of the elongate member to butt against.

In alternative embodiments the socket 13 may receive fluid through openings in other locations, and may comprise a different shape.

The fluid supply hose 134 in preferred embodiments transfers fluid from an external fluid source (not shown) to the side entrance 133 of the socket 13. The external fluid source may comprise a pump, reservoir, or a unit comprising both. In the preferred embodiment the fluid supply hose 134 enters the outer housing 10 through an opening 101 , and passes through base packing 121 to reach the socket 13, The fluid supply hose 134 may be rigid or flexible.

Ram

In the embodiment of Figures 1 and 2 the ram 20 comprises a cylindrical shape with a flat upper surface and an internal ram cavity 22. The body of the ram may be filled with grout 26, with a number of equispaced vertical ram rods 27 to provide the ram 20 with strength. Preferably the ram rods 27 are formed from steel or another material able to provide the ram 20 with sufficient strength to withstand impacts or pressures whose magnitude depends on the situation in which the ram is used.

The ram design according to preferred embodiments allows for high strength while using relatively cheap materials, such as the grout used to fill the ram. Existing bollard designs with hollow rams have bulky internal mechanisms, which means that the ram walls are thin, adversely affecting the strength of the ram. The ram of the present invention has a relatively small internal cavity, allowing for a greater wall thickness providing higher strength, especially in combination the use of the grout filling and vertical reinforcement rods, both of which are relatively cheap.

While existing designs comprising a solid ram may be slightly stronger as a result of a higher area moment of inertia, the ram according to the present design has material removed only from the middle, which is nearest the neutral axis of the ram, and will therefore have a minimal effect on area moment of inertia. For some installations, this minor sacrifice of area moment of inertia may be outweighed by the overall advantages provided by the present invention, such as the reduced depth, and easier and cheaper construction, installation and maintenance.

In preferred embodiments, around the outer cylindrical surface of ram 20 is an outer sleeve 28, and within the ram cavity 22 is an inner sleeve 29. Both sleeves 28 and 29 provide a suitable surface to which seals may engage, and may be made of a conductive material. Inner sleeve 29 comprises a cavity plate 291 made of a conductive material.

In some embodiments there may be electrically insulating tape wrapped around the ram 20 between the grout 26 and the outer sleeve 28. This may be particularly necessary in order to prevent electrical conductivity between the inner sleeve 29 and the outer sleeve 28 if the grout 26 becomes electrically conductive over time, or if a conductive type of grout mixture, for example one comprising metallic filings or other conductive particles, is used. Discussion further below describes reasons for considering the electrical properties of the ram.

In preferred embodiments ram 20 comprises a cap 201 which may comprise electronics such as control circuitry, sensors, light or sound emitting devices to warn vehicles and pedestrians in the vicinity of the bollard 100, and optionally illuminate the ram 20. In preferred embodiments the ram cavity 22 comprises a shield 221 which is a shielding means providing a barrier to substantially prevent or hinder contaminants, dirt and the like from entering further into the ram cavity 22 than the location at which the shield 221 is positioned. The shield 221 may be in the form of an electrically conductive wire wool packing fixed to the cylindrical wall of the ram cavity 22, with an internal diameter which, while in use, substantially matches the outer diameter of the elongate member 41. Being fixed to the wail of the cavity 22 near the lower end, the shield 221 is able to move vertically relative to the elongate member 41 as the ram 20 is extended and contracted.

As briefly discussed previously, in preferred embodiments a stop ring 25 is fixed to the outer wall of the ram 20 and adapted to contact the lower surface of the collar 30 and prevent the ram from extending further upwards than is possible according to the vertical positioning of the stop ring 25. There is a stop cushion 251 , for example an O-ring type component on top of the stop ring 25 to provide impact absorption and prevent damage to the stop ring 25 or collar 30. The stop ring may be of unitary construction or separate parts, for example multiple stops spaced around the perimeter of the ram. In some embodiments, the ram may be free to rotate about its vertical axis. In which case, the stop ring 25 may be a complete ring around the entire circumference of ram 20 to ensure contact with the collar 30 for any rotational position of the ram. In preferred embodiments a ram support collar 21 is fitted to the lower end of the ram on the outer wall and is of a substantially equal diameter to the internal diameter of the outer housing 10. The ram support collar 21 is adapted to produce minimal friction with the inner wall of the outer housing 10, for example being covered with a low friction skin. The ram support collar 21 provides support to the lower end of the ram 20 in the event of an impact, and is of a sufficient length such that the force applied to the ram 20 in an impact is distributed over a sufficient area of t e Inner wall of the outer housing 10 to minimise or prevent damage.

Fluid Injector

In preferred embodiments the fluid injector 40 comprises elongate member 41 , with head 42 welded to the upper end of elongate member 41 and comprising head passage 421 allowing fluid communication between the injector passage 411 and the chamber 24. Air filter 422 is a means of shielding the interior of the chamber prevent contaminants from entering the chamber 24 with the supply of air, or when the ram has been removed from the housing. The elongate member 41 comprises at its lower end a socket seal 412 to seal with the upper entrance 131 of the socket 13.

The head 42 comprises upper head seal 43a and lower head seal 43b which both provide a fluid tight seal against the ram cavity 22 to prevent fluid from escaping from the chamber 24. Upper head seal 43a may be energised when the air pressure inside chamber 24 is greater than the air pressure on the other side of upper head seal 43a. Lower head seal 43b may be energised when the ram 20 is moving downwards fast enough to create a higher pressure below the seal than above it. This arrangement ensures the chamber 24 remains airtight, and helps prevent build-up of contaminants between the upper and lower head seals 43.

As described with reference to the collar seals 31a and 31 b, there are various

arrangements of seals and other components within the scope of the various

embodiments of the invention, all of which would be evident to a person skilled in the art based on the description herein. For example in some embodiments, only upper head seal 43a is used to seal the head 42 within the ram cavity 22.

Method of Disassembly and Assembly

One of the many advantages of the present invention is the ability for maintenance to be performed on the bollard without exposing the interior of the sealed chamber and/or the surfaces that bound the pressurised chamber on which the seals slide. The preferred embodiments allow the bollard to be assembled and disassembled by personnel with little to no experience with bollards. This advantageously reduces maintenance costs when compared to many existing bollard designs, which require specialised and experienced personnel to perform the assembly and disassembly steps. In contrast, a bollard according to the preferred embodiment can be disassembled simply by removing the collar and lifting the ram out with the fluid injector inside protecting the sealing surfaces, and can be reassembled by simply lowering the ram and fluid injector together back into the outer housing and refastening the collar. The simplicity of these steps allows them to be performed by inexperienced personnel. The process is described in further detail below.

Figure 3 shows the bollard 100 according to an embodiment of the invention in a configuration in which the ram 20 can be removed without exposing the walls of the chamber 24. This is accomplished by removing both ram 20 and the fluid injector 40 together from the open end of the outer housing 10. In this configuration, the upper and lower head seals 43a and 43b remain in sealing contact with the walls of cavity 22.

Furthermore, shield 221 prevents exposure of the other surfaces of the cavity inside ram 20 that the seals can slide against in normal use. The air filter 422 further prevents contaminants from entering into the sealed chamber or contacting the internal working surfaces of the ram. In other embodiments, there may be no air filter but, in the ram- removal configuration, the top of the elongate member abuts against the upper inner surface of the ram cavity, forming a seal from the rest of the cavity and its surfaces.

In a preferred embodiment the method involves a series of steps as follows. First the ram 20 is forced downwards by removing fluid from the chamber 24 and maintaining a negative gauge pressure within the chamber. This forces the ram 20 and fluid injector 40 together, in the same configuration as when the bollard 100 is fully retracted. While maintaining the negative gauge pressure within the chamber 24, the collar 30 is removed. Removing collar 30 may involve removing fasteners as required depending on the various possible collar designs within the various embodiments of the present invention.

Removing the collar 30 before applying the negative gauge pressure to chamber 24 would also fall within the scope of the invention.

The negative gauge pressure may be achieved by preventing any transfer of fluid into the chamber 24, or allowing only a limited amount of fluid to enter chamber 24 while the ram 20 is being removed to induce a pressure within the chamber lower than that outside the ram, for example a pressure lower than atmospheric pressure. After the collar 30 is removed, the ram 20 is lifted from the open end of outer housing 10 with lifting eye bolts that fit into lifting eye bolt holes 203. As the collar 30 is no longer mounted to the top of the outer housing, the stop ring 25 and ram support collar 21 do not contact any parts within the assembly of bollard 100, and the ram 20 is able to be removed.

While the ram 20 is lifted from the outer housing 10 the negative gauge pressure within the chamber 24 is maintained. This prevents the fluid injector 40 from moving vertically relative to the ram 20 provided the negative gauge pressure is sufficient. If necessary the negative gauge pressure is increased, or increases as required to counteract the weight of the fluid injector 40. The fluid injector 40 is therefore removed with the ram 20, while still maintaining the relative position between the two components as they would be positioned if the bollard 100 was fully retracted. This ensures that the upper and lower head seals 43a and 43b remain sealed to the wall of the ram cavity 22 and the entirety of the wall of ram cavity 22 over which the seals 43a and 43b travel remains shielded from

contaminants by shield 221 and air filter 422.

In some embodiments the head 42 may comprise a foam pad on its upper surface in order to absorb any impact between the fluid injector 40 and the upper surface of the ram cavity 22, and also may increase the ability of the fluid injector to seal to the upper surface of the ram cavity if a negative pressure is applied to the chamber 24 in order to remove the ram 20 and fluid injector 40 together.

After the ram 20 has been lifted far enough for the elongate member 41 of the fluid injector 40 to become removed from the socket 13, the friction between the upper and lower head seals 43a and 43b and the inner wall of the ram cavity 22 prevents the fluid injector 40 from falling from within the ram 20 while they are lifted from the outer housing 10 together. The ram 20 can then be transported safely to a workshop or other controlled environment where the inner workings of the ram 20, which are vulnerable to

contaminants, can be maintained more easily.

After maintenance, ram 20 and fluid injector 40 can be transported together back to the location where the rest of the bollard 100 is installed, and they can be reinserted together by lowering the ram 20 back into the outer housing 10 with the fluid injector 40 already inserted into the ram cavity 22. The elongate member 41 of the fluid injector 40 is easily inserted into the upper opening 131 of socket 13, and the ram 20 is lowered or pushed down until the lower end of the elongate member 41 makes contact with the internal shoulder around the socket passage 132. The collar 30 can then be reinstalled.

Electrical connections

Preferred embodiments of the present invention are advantageous over many traditional bollard designs as, in some embodiments, the retractable bollard does not need a trailing electrical connection. In preferred embodiments, various components of the bollard are used as part of an electrical system integrated within the bollard. These components may also perform other functions, for example structural functions. The electrical connections between these components may be configured such that different electrical circuits form between components of the bollard depending on the position of the bollard. As a result, the position of the bollard at a given time can be detected.

In a preferred embodiment a voltage may be applied to the ram, and that voltage may be used to power electrical components within the ram, for example at the head. If the ram is in an intermediate position (i.e. between the fully retracted and extended positions), a circuit may exist between the ram, the electrical components within the ram, and the outer housing. Appropriate electrical connections between these components enable current to flow. A controller may be adapted to recognise the electrical characteristics of the ram when this particular circuit is formed, and therefore detect that the ram is in an intermediate position. The electrical components in the cap in this scenario are able to receive power and operate.

Additionally, if the ram is in a fully extended position, a different circuit may be formed as a result of electrical connectors that come into contact when the ram is fully extended. This circuit has detectably different electrical characteristics (e.g. lower resistance) than the circuit formed when the ram is in an intermediate position. The controller is configured to detect from the different electrical characteristics of the ram that the bollard is fully extended, and can operate accordingly. Finally, if the ram is in a fully retracted position, a different circuit again may be formed as a result of electrical connectors that come into contact when the ram is fully retracted. This circuit also has electrical characteristics that are detectably different from those of the fully extended and intermediate positions.

It will be appreciated that, in some embodiments, a circuit with differing electrical characteristics may only be formed when the ram is fully extended, or only when the ram is fully retracted, and as a result only the respective configuration can be detected.

In some embodiments, the circuit powering the components in the head of the ram may short when the bollard is fully retracted, and the controller may recognise the short circuit based on the electrical characteristics of the ram and therefore identify that the bollard is fully retracted. In this case, a current limiter may be used to prevent current from flowing around the short circuit, preventing possible damage.

With reference to Figures 1 and 2, the electrical connections of the bollard according to a preferred embodiment of the invention are described below.

The socket 13, elongate member 41 , shield 221 , inner sleeve 29 and cavity plate 291 of ram cavity 22, cap 201 , outer sleeve 28 of ram 20, stop ring 25, collar bolts 35 and metallic base plate 123 are all electrically conductive. A conductive shaft 202 electrically connects the cavity plate 291 of ram cavity 22 with electrical components within the cap 201. At least the lowest portion of the cap 201 may be electrically insulating to ensure that the conductive shaft 202 is electrical isolated from the outer sleeve, so that current must first flow through from the conductive shaft through any electronic components (for example warning lights/sounds) before flowing to the outer sleeve.

Some components within the bollard 100 are connected via electrically conductive cables or similar means to a voltage supply and a controller (voltage supply and controller not shown in the Figures). A positive voltage relative to ground is provided to the socket 13 via socket cable 51. A down cable 52 provides an electrical connection from the metallic base plate 123 to the controller. An up cable 53 provides an electrical connection from the outer housing 10 at the level of the stop ring 25 while the ram 20 is fully extended, to the controller. An intermediate cable 54 provides an electrical connection from collar bolt 35 to ground. A sprung electrical connector or similar component electrically connects the stop ring 25 to the up cable 53 when the ram 20 is fully extended. A sprung electrical connector or similar component electrically connects the outer wall of the ram 20 with a collar bolt 35, and the intermediate cable 54 electrically connects the collar bolt 35 to ground.

Intermediate ram position is therefore identified by the controller when only intermediate cable 54 is grounded.

The controller can therefore identify whether the ram 20 is fully retracted, fully extended or in an intermediate position, all while powering electronics in the cap 201.

A circuit therefore always exists between the socket cable 51 , socket 13, elongate member 41 , shield 221 , inner sleeve 29 and cavity plate 291 of ram cavity 22, conductive shaft 202, electronics in the cap 201 , outer sleeve 28 of ram 20, a sprung connector to collar bolt 35 and intermediate cable 54. This allows electronics in the cap 201 to be powered regardless of the position of ram 20.

When the ram is fully retracted, an additional electrical circuit is formed between outer wall of ram 20, metallic base plate 123, and down cable 52. This circuit has different electrical characteristics that are detectable by the controller and indicate that the ram 20 is fully retracted, for example by a circuit being formed with down cable 52. When the ram is fully extended, an additional circuit is formed between outer wall of ram 20, stop ring 25, and up cable 53. This circuit has different electrical characteristics again that are detectable and indicates to the controller that the ram 20 is fully extended, for example by a circuit being formed with up cable 53. If both these circuits are open, the electrical characteristics of the resulting circuit(s) indicate to the controller that the ram 20 is in an intermediate position, yet a circuit may still be formed with intermediate cable 54, allowing current to power any electrical components within the ram and flow to ground.

In a preferred embodiment the circuit formed with down cable 52 when the ram is fully retracted allows any electrical components in the ram 20 to remain powered while the ram is fully retracted (for example lights and sound emitted from the cap 201). This may be important for warning approaching vehicles and/or pedestrians that the bollard is about to extend, and is advantageous in that the warning is emitted from the bollard itself.

It will be understood that a detectable change in electrical characteristics includes any change in an electrical circuit that can be detected by any means. This may include a change in parameters of the circuit itself, or a change in the output of the circuit, or a change in the output of a device powered by the circuit. The invention is not limited by the manner in which the different circuit configurations resulting from the different positions of the ram are detected.

A person skilled in the art will understand that there are many variations of the electronics of the bollard according to various embodiments of the invention. For example, not every circuit must return to the controller. One or more of the circuits may travel between the controller and the ground, and/or one or more of the circuits may short, indicating a particular configuration to the controller. Alternative Embodiments of the Invention

Embodiments of the invention allow the ram and/or other components to be removed from the remainder of the bollard assembly without exposing the sliding or working surfaces in the assembly. One ram according to an embodiment of the invention has already been described. In another embodiment, an alternative bollard design may be employed involving a solid ram and a sealed chamber underneath the ram within an outer housing.

There may be two outer housings in such a design, one that is permanently embedded, and one that is configured to be able to be removed with the ram. The lower end of the ram may slideably seal with the bore of the removable housing, and the upper end of the removable housing may slideably seal with the outer surface of the ram. The removable housing may be able to be fastened to the outer housing and such that it is fixed in place during normal use of the bollard, but may be unfastened from the outer housing for removal.

In such an embodiment the lower seals may be fixed to the ram and travel up and down, forming a boundary of an expanding chamber below the ram, while the upper seals may be fixed to the removable housing and remain in position relative to the ram to prevent water or contaminants from entering into the space above the traveling seals and contaminating the surface over which the ram seals slide.

The removable housing may have an opening at its lower end either on the side or bottom such that fluid can be supplied to the chamber below the ram. The removable housing may be lifted out of the embedded housing, without removing the ram from within, when maintenance is required to be performed offsite without separating any of the seals from the surfaces over which they slide. Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like, are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense, that is to say, in the sense of "including, but not limited to".

The entire disclosures of all applications, patents and publications cited above and below, if any, are herein incorporated by reference. Reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that that prior art forms part of the common general knowledge in the field of endeavour in any country in the world.

The invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, in any or all combinations of two or more of said parts, elements or features.

Where in the foregoing description reference has been made to integers or components having known equivalents thereof, those integers are herein incorporated as if individually set forth.

It should be noted that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the invention and without diminishing its attendant advantages. It is therefore intended that such changes and modifications be included within the present invention.