GB2423791A

GB2423791A - Removable post comprising shaft with bayonet coupling slot

Info

Publication number: GB2423791A
Application number: GB0506582A
Authority: GB
Inventors: Peter Boote
Original assignee: Specialty Fasteners and Components Ltd
Current assignee: Specialty Fasteners and Components Ltd
Priority date: 2005-02-25
Filing date: 2005-03-31
Publication date: 2006-09-06
Anticipated expiration: 2025-03-31
Also published as: GB0506582D0; GB0504027D0; GB2423791B; WO2006090156A1; EP2049738A1

Abstract

A removable post comprises an elongated main body (1, Fig. 1) having an aperture at one end (2, Fig. 1) and a shaft 3 axially movable relative to the main body between an extended position and a partially retracted position. The shaft has a locking slot 22a forming part of a bayonet coupling, and a radial flange 9 axially spaced from the locking slot. An actuating pin 8 extends through the main body, the pin having a cam surface 8a which engages the flange such that rotation of the pin moves the shaft between its two positions. The removable post may be connected to an anchor plate 30 having a tab (32A, 32B, Fig. 3a) which engages with the locking slot 22a, 22b. The pin 8 may subsequently be rotated to move the shaft to its partially retracted position and lock the post relative to the anchor. Also disclosed is a removable post comprising a shaft (101, Fig. 9) having a bayonet coupling slot (102), a threaded portion (108), and a nut (106). The nut may be rotated to engage an anchor with which the coupling slot is engaged, moving the shaft relative to the anchor thereby locking them together.

Description

Ouick Release Post A Ouick Release Locking Post Assembly & Bayonet Type

shaft Anchoring system The present invention relates to quick release locking post assemblies & bayonet type shaft anchoring systems.

Removable posts are used for a wide number of applications where temporary positioning of a post is required. For example, if it is required to erect a temporary barrier, a series of spaced apart posts are often provided with beams made of wood or plastic extending between them. This is achieved in one approach by providing each post with a base which stabilises it. However, this approach has the drawback that the base must be made very heavy in order to offer any meaningful resistance against toppling over following an impact, for example by a passer-by, making them awkward to move around. Furthermore, even posts with heavy bases can still be moved and/or knocked over relatively easily due to the leverage afforded by the length of the post, and if the posts are too heavy they can lead to health and safety issues with regard to their being carried by personnel.

An alternative solution, in applications where posts are repeatedly going to be required to be used in the same location, is to provide an anchor point in the ground into which the post can be fixed, either simply by dropping into the hole or by provide a thread on the end of the post which screws into a complementary thread provided in the hole. Such systems are often used not only in application such as barrier posts of the type mentioned above, but also, for example, for securing legs of fold-away tables, and the like. Whilst these systems overcome the problems of security and stability of the posts, they require an opening to be present in the ground where the posts are to be used, which is often in areas to which members of the public and the like will have access when the posts are not in place. This raises health and safety issues due to the possibility of a passer-by getting a shoe heel or the like stuck in an exposed opening. Even providing plugs for the holes is not an acceptable solution due to problems of their being lost andlor removed by unauthorised persons.

According to the present invention there is provided a removable post comprising an elongated main body having a cylindrical aperture extending from at least one end thereof, a shaft concentrically mounted in said cylindrical aperture so as to be axially movable relative to said main body between a first extended position and a second partially retracted position, said shaft having at least one projections of arcuate crosssection provided on an end thereof, the or each projection extending from said at least one end of the main body, terminating in the circumferential direction at an axially extending slot and including a locking slot which intersects with and extends circumferentially from said axial slot so as to form a first part of a bayonet coupling said shaft further including a radial flange axially spaced apart from said projections and a longitudinally extending slot which extends from said flange towards said projections, wherein an actuating pin extends through said main body and engages in said slot, which pin has a cam surface formed which is engaged by said flange such that, upon rotation of the pin, the flange is moved axially relative to the centre of the pin, thereby causing the shaft to move between its extended and partially retracted positions.

A removable post in accordance with the invention has the advantage that it may be configured to operate with very narrow anchor openings provided in the anchor surface, thereby avoiding the possibility of a pedestrian trip on the anchor opening, whilst still ensuring that sturdy anchoring of the post is achieved. Furthermore, the provision of the pin in the post enables the post to he locked in place in a very simple manner by retracting the shaft against radially extending pins of a mating bayonet coupling plate.

Preferably, the post is provided with at least two projections which are separated from each other on either side by axially extending slots.

Preferably, the radial flange takes the form of a load plate which is mounted on the shaft. In a particularly preferable embodiment, the pin engages with a lower surface of the load plate which is slidable mounted on the shaft, spring means such as Belleville spring washers or the like engaging with the upper surface of the load plate so as to bias the load plate axially away from a reaction plate, in particular formed by a nut screwed onto the end of the shaft or alternatively a fixed plate forming a reaction flange, and into engagement with the pin. Rotation of the pin then presses the load plate towards the reaction plate, compressing the spring therebetween, which, in turn urges the reaction plate away from the bottom end of the post, thereby causing the shaft to retract into the post. This arrangement has the advantage that the spring tensions the joint, maintaining a high load requirement for rotating the pin in or to lock or release the post and hence preventing unauthorised operation.

In a particularly simple configuration, the pin has a flat formed on it at a first perpendicular distance from its axis of rotation, the remainder of the cross-section of the pin being circular with a radius which is greater than said first perpendicular distance. In this way, when said flat is engaged against the load plate, the shaft adopts its extended position relative to the post under its own weight andlor under the biasing action of the spring, and upon rotation of the pin so as to being the curved portion of the cross-section into engagement with the load plate, the plate is urged away from the central axis of the pin, thereby retracting the shaft. Of course, it will be understood that other cam profiles may also he utilised on the pin.

The present invention further provides an anchor for a removable post comprising a plate having at least one arcuate through slot formed therein which extends along a circular arc around the centre of the pin and terminates at a radially extending spacing tab, under which an undercut of a bayonet coupling of a post according to the invention is engageable so as to lock said post to said anchor.

Preferably the plate has at least two arcuate slots which each extend through less than degrees along a common circular arc on opposite sides of a common centre, each end of each slot being separated from the proximate end of the other slot by a spacing tab.

The slots of the anchor are sized and shaped to complement the projections on the shaft of the post, such that the projections can be engaged through the slots with spacing tabs of the anchor engaging in the longitudinal slots separating the projections.

Preferably, the anchor further includes a pot or insert which is recessed into the ground and secured in place, for example, by concreting or the like. The plate may be integrally formed with the pot or may be removable fastened thereto, for example by means of a screw which engages in a threaded opening in a central pin fornTled in the pot or by means of mating male and female threads formed on the plate and pot directly. The pot furthermore advantageously has spines or ribs formed on its outer surface to assist in securely fastening it into the ground. The pot is hollow in order to accommodate the projections on the post, and in a preferred embodiment has a central post formed in it so as to provide an annular chamber between the outer surface of the central post and the inner surface of the outer wall, in which annular chamber the projections engage. In particular, the chamber is advantageously sized to he a close fit with the projections so as further to improve the stability of the post.

According to another aspect of the present invention there is provided an anchoring system for a shaft comprising a shaft having an annular cross section extending from one end at least partially towards the other end thereof and a threaded portion provided on its outer surface proximate to hut spaced apart from said one end, and a nut provided on the shaft which is threadingly engageable with the thread provided on the shaft such that the nut is screwable along the shaft towards and away from said one end, at least one bayonet coupling slot being provided in the shaft extending from said one end, the coupling slot penetrating through the annular wall of the shaft and having a first portion which extends axial from the one end of the shaft, a second portion which extends circumferentially from said first portion partially around the circumference of the shaft, and a third portion which is parallel to but circumferentially spaced apart from said first portion and extends from the second portion axially towards the one end of the shaft, said third portion terminating in a closed end which is spaced apart from said one end of the shaft, wherein, in use, said one end of the shaft engages with an anchor means having a radial member which engages in said coupling slot, moving along the first portion upon insertion of the shaft, and along the second portion upon twisting of the shaft following insertion, whereupon the nut is screwed towards the one end of the shaft, bringing it into engagement with the anchor means and lifting the shaft relative to the anchor means whereupon the radial member is trapped in the third portion of the coupling slot.

The shaft may be provided with a plurality of coupling slots distributed about is circumferential, the second portion of each extending in the same direction from the first portion, and the anchor means then being provided with a corresponding number of radial members for engagement in the coupling slots.

Preferably, the system is used in combination with an anchor according to the invention.

In order that the invention may be well understood, there will now be described some embodiments thereof, given by way of example, reference being made to the accompanying drawings, in which: Figure 1 is a perspective view of a removable post according to the invention; Figure 2 is a longitudinal sectional view through the post of Figure 1; Figures 3a to 3c are top, side and end views, respectively, of an anchor plate which cooperates with the removable post in order to anchor it in place; Figure 4 is an enlarged perspective view of the anchor plate and mating end of the post; Figures 5a to 5d are various views of an anchor pot suitable for use with the anchor plate of Figures 3a to 3c; Figure 6 is an exploded side view of the post, anchor plate and anchor pot of the invention; Figure 7 is a perspective view of a tool which can be used in conjunction with the present invention to facilitate the operation of potting in the potting plug; Figure 8 shows various developments and alternative embodiments of the invention; and Figure 9 is a perspective view of a bayonet type shaft anchoring system according to another aspect of the inventionl Referring first to Figures 1 and 2 there is shown a post according to the invention formed by a cylindrical body 1 having an upper end (not shown) and a lower end 2 from which extends a bayonet coupling as described in more detail below. A shaft 3 is slidably mounted in the lower end 2 of the body 1 so as to extend co-axially inside the body I from the lower end toward the upper end, the central position of the shaft 3 within the body 1 being maintained by a bush 4 which is housed within the body 1 and engages between the inner cylindrical wall thereof and the outer surface of the shaft 3 (it will, of course, be understood that more than one bush may be used depending on the length of the shaft). The upper end 3a of the shaft 3 has a threaded portion 5 formed on its external surface, and also has a diametrical slot 6 formed in it, which slot is elongated in the axial direction of the shaft and aligns with a radial aperture 7 formed in the cylindrical wall of the body 1 such that actuating pin 8 located in the aperture 7 engages in the slot 6 as shown in Figure 2.

A load plate 9 is freely slidably mounted on the outer surface of the shaft 3 above the slot 6 such that it rests against the pin 8. A pair of Belleville washers I Oa, I Oh are also slidably mounted, in back to hack orientation (although other orientations such as face to face are also possible), on the outer surface of the shaft 3 above the load plate 9 and are tensioned against the load plate 9 by means of a tensioning nut 11 which is adjustably secured to the threaded portion 5 of the upper end 3a of the shaft 3. A lock nut 12 is also screwed onto the threaded portion 5 above the tensioning nut 11. As shown in Figure 2, the pin 8 has a cross-section which has a cain profile, in particular having a first portion 8a with a generally circular cross-section centred on the longitudinal axis of rotation of the pin 8 and a second portion 8h formed by a flat which extends between the ends of the first portion 8a, the perpendicular distance of the second portion 8h from the longitudinal axis of rotation of the pin 8 being less than the radius of the substantially circular section. Accordingly, starting from a position in which the flat portion 8b is oriented parallel to and is in abutment with the load plate 9, rotation of the pin 8 causes a camming action to he developed with the load plate as flat portion 8b is inclined to the load plate 9 and then the circular portion 8a engages the load plate 9, pressing the load plate 9 towards the Beilville washers lOa, lOb, which, in turn, transfer the load to the adjusting nut 11, urging it away from the lower end 2 of the body 1, and, due to its attachment to the shaft 3, causing the shaft partial]y to retract axially into the body I by a distance equal to the different between the radius of the first second 8a of the pin and the perpendicular distance of the second section 8b away from the axis of rotation. The tension of the Beliville washers I Oa, lOb ensure that the frictional engagement between the load plate 9 and the surface of the pin 8 is sufficient to prevent accidental or unauthorised rotation of the pin 8. The shaft 8 is released from its retracted position simply by rotating it until the second portion 8h is again in engagement with the load plate 9, whereupon the force of the Beliville washers and the weight of the shaft 3 causes the shaft to return to its fully extended position, the movement in both directions being guided by the bushes 4. Rotation of the pin 8 is effected by means of a suitable key which engages with the end of the pin 8 which is exposed on the outer surface of the body 1, such as an allen key which engages in an opening in the end of the pin 8, a lever, which may he permanently or releasably attached, or the like.

Formed on the lower end 3b of the shaft is a bayonet coupling formed by an annular extension 20 of substantially circular cross section, which extends from the lower end 2 of the body 1. The annular extension 20 is divided into two arcuate projections 20a, 20b by a pair of slots 21a, 21b located on diametrically opposite sides of the extension, each slot extending radially through the annular wall of the extension 20 and axially along the extension towards the body I as shown in Figure 1. The end of each slot 21 a, 21 b proximate to the projecting end of the extension 20 is also tapered so as to widen towards said end, thereby providing a funnelling effect into the slots so as to facilitate proper locating/aligiirnent of the post in its mounting box as described below. Furthermore, the end of each slot 21 a, 21 b proximate to the body I intersects with a respective circumferential slot 22a, 22b which again penetrates through the annular wall of the extension 20 and which extends circumferentially partially around the annular extension 20. Each said circumferential slot 22a, 22b, at its end remote from its associated axial slot 21 a, 2 ib, has a depression 23 formed in its wall remote from the body 1, which forms a capture point in the slot 22a, 22b as described hereinafter. A cap 25 is also provided on the lower end 2 of the body I to close the radial space between the shaft 3 and the body 1.

Referring now to Figure 3a, there is shown a plan view of an anchor plate 30 which co-operates with the protruding end of the shaft 3 in order to anchor the post in place.

The anchor plate 30 is of circular shape and has a pair of substantially semi-circular, concentric arcuate slots 31 a, 3 1 b extending axially between its upper and lower surfaces, the shape and thickness of said slots being complementary to the shape and thickness of the arcuate projections 20a, 20b provided on the end of the shaft 3 such that said projections are engageable through said slots. The slots 3 la, 3 lb are furthermore separated at each end by a radially extending spacing tab 32a, 32b. the width and thickness of which are such that each tab 32a is engageable in the axial 21a, 21h and circumferential 22a, 22b slots of the bayonet coupling formed on the lower end of the shaft 3.

In order to secure the post to the anchor plate 30, the pin 8 is rotated to its release position in which the flat 8b formed thereon is engaged with the load plate 9 and the shaft 3 is therefore in its fully extended position. The projecting end of the shaft 3 is then positioned over the anchor plate 30 with the arcuate projections 20a, 20b aligned with the two arcuate slots 3 I a, 31 b of the anchor plate and the spacing tabs 32a, 32b substantially aligned with the axial slots 21 a, 21 b formed in the extension 20, and the post is then lowered towards the anchor plate. The funnelled mouths of the axial slots 21 a, 21 h ensure that the tabs 32a, 32b are captured by the slots even if not perfectly aligned and are guided into the narrowed section thereof, the projections then dropping through the arcuate slots 31a, 31b until the spacing tabs 32a, 32b reach the ends of the axial slots 21a, 21b and are aligned with the circumferential slots 22a, 22b. The post is then rotated about its longitudinal axis, capturing the spacing tabs in the circumferential slots and hence preventing removal of the projections from the arcuate slots. When the post has been fully rotated so that the spacing tabs are positioned at the ends of the circumferential slots in the region of the depressions 23, the pin 8 in the post is rotated to bring the its arcuate surface 8a into engagement with the load plate so as to retract the shaft into the post I as described above, whereupon the depressions 23 move towards the spacing tabs, capturing them therein and thereby preventing rotation of the post in the opposite direction as is required in order to remove release the post from the anchor plate. In order so to release the post, the pin is rotated back to a position in which the flat 8b is again engaged against the load plate, whereupon the shaft is allowed to return to its fully extended position and the spacing tabs are re-aligned with the circumferential slots so as to allow rotation of the post in order to move the tabs along the circumferential slots to the axial slots and then removal of the projections.

A potting plug 40 as shown in Figures 5a to Sd, is provided for securing the anchor plate in the ground. The potting plug 40 has a body 41 which, in the illustrated embodiment is circular to facilitate its potting in the ground but may also he other shapes, has a plurality of ribs 42, or in an alternative embodiment a thread formed on its other surface to assist on securing the plug 40 in place. As shown in the sectional view of Figure 5d, the plug 40 has an annular outer wall 43 and a central post 44 which extends coaxially with the outer wall 43 and is integrally formed with the body 41, said outer wall 43 and central post 44 between them defining an amrnlar channel which is sized and shaped to align with the arcuate slots 31a, 31b formed in the anchor plate 30 when it is fastened to the plug 40.

The central post 44 furthermore has a threaded hole 46 formed centrally in it which aligned with a corresponding countersunk hole formed in the anchor plate so that a screw 50 may be inserted through the anchor plate and screwed into the threaded hole 46 in order to secure the anchor plate 30 to the plug 40 as shown in Figure 6. The anchor plate 30 also includes a pair of feet 34 which extend from its lower surface at diametrically opposite sides of the plate 30, which feet 34 engage in locating apertures 48 provided in opposing pairs at different circumferential positions in the mouth of the plug so as angularly to locate the plate in the plug. In particular, four pairs of apertures 48 are provide which enable the plate to he fastened to the plug in four different angular orientations at 45 degrees to each other. Alternatively, the plate may have serrations or teeth formed on its outer circumference which engage with complementary teeth formed on an inner circumferential face of the plug so as to lock the plate in a fixed position relative to the plug, this having the particular advantage that the plate may easily be adjusted into a number of different radial orientations relative to the plug.

The alignment of the arcuate slots 31 a, 3 lb of the anchor plate 30 with the annular channel 45 formed between the outer wall 43 and central post 44 of the plug 40 ensures that the arcuate projections 20a, 20b of the shaft 3 engage in the annular channel 45. In an alternative embodiment not illustrated, however, the central post may be omitted so that the plug simply provided a cylindrical aperture into which the projections engage. In that case, the anchor plate may be secured to the plug, for example, by means of threads formed on its outer edge which engage with complementary threaded formed on the inner circumferential surface of the outer wall of the plug. Alternatively, a threaded hole may he provided in the base of the plug with a long screw being used to secure the plate to the plug through a central hole formed in the anchor plate.

In a still further embodiment, the anchor plate may be integrally formed with the plug.

The angular orientation of the post relative to the anchor plate is fixed by the design of the post and may be important if, for example, the post includes brackets at fixed locations on its outer surface which must align with corresponding brackets formed on neighbouring posts in order to enable a barrier to be engaged therehetween. To facilitate in correct alignment, therefore, the plug may be provided with a marker which indicates a primary radial direction of the post when properly fastened to the anchor plate, which, when installing, a user must align with markers provided on previously installed plugs in order to ensure that the posts can properly interface with each other.

In order to facilitate the process of potting in the potting plug, and in particular to enable easy rotation of the plug when potting into correct alignment with other plugs, a tool is provided as shown in Figure 7 having a pair of tabs 61 a, 61 b which extend upwardly from an upper surface of a plate body 60, which tabs form finger grips.

Projecting from lower face of the body 60 is a pair of arcuate projections 62a, 62b of complementary size and shape and positioned to engage into the arcuate slots 31 a, 3 lb formed in the anchor plate. Furthermore, two pair of claws 63, 64 extend from the lower face of the body 60, one pair being positioned between each pair of adjacent ends of the projections 62a, 62b, the claws being sized and shaped to engage the spacing tabs 32a, 32b on the anchor plate in order to lock the tool to the plate.

The tool thereby engaged the installer easily to transmit torque to the plug through the anchor plate, thereby enabling the plug to he turned into correct alignment.

Alternatively, a tool may simply be screwed into the threaded hole provided either in the central post of the base of the potting plug.

In a further development, a threaded rod may he used to further improve the anchoring of the pot in the ground, the rod being screwed at one end into a complementary threaded recess in the bottom of the pot in order to attach it thereto and at the other end into a hold provided in the bottom of the potting recess.

Preferably, the thread and at least said other end of the rod is selftapping.

Referring now to Figure 9, there is shown a perspective view of an anchoring system for shafts or po]es such as scaffolding poles. As illustrated in Figure 9, the shaft 101, for example a scaffolding pole, is of tubular construction and has a female bayonet coupling 102 provided proximate to its lower end, by which, in use, the shaft 101 will be anchored. The female bayonet coupling 1 02 comprises a first axial through slot 103 which extends from the lower end of the shaft 101 towards the upper end and joins with one end of a circumferential through slot 104 which extends partially around the shaft 101 and intersects with a second axial through slot 105 which extends parallel to the first axial through slot 103, away from the circumferential slot 104 towards the lower end of the shaft 101 but terminating short of said lower end so as to form a closed channel. A second female bayonet coupling slot is also provided on the opposite side of the shaft (not shown), the circumferential slot of which extends in the same direction from the first axial slot as the circumferential slot of the first female bayonet coupling 102 (anti-clockwise as illustrated).

A male thread 108 is also provided on the outer surface of the shaft above the female bayonet coupling, which is threadingly engageable by a threaded nut 106 provided on the shaft 101 SO as to enable the nut 1 06 to he screwed axially towards and away from the bayonet coupling. The nut 106 includes a flange plate 107 on its lower surface wiuch operates as a reaction flange. engaging against a surface surrounding the lower part of the shaft 101 as the nut is screwed down the thread towards the lower end of the shaft so as to lift the shaft 101 relative to said surrounding surface The shaft anchoring system of Figure 9 is used in combination with the potting plug of Figures 5a to SD or the like and anchor plate 30 of figure 3a. In use, the lower end of the shaft 101 is inserted into the potting plug 40 with the first axial slots 103 on opposing sides of the shaft 101 aligned with the radial spacing tabs 32a, 32b of the anchor plate 30 As the shaft is inserted into the potting plug 40, the spacing tabs 32a, 32b slide along the first axial slots 103 until they reach the upper ends thereof The shaft 101 is then twisted in a clockwise direction, causing the spacing tabs 32a, 32b to slide along the circumferential slots 104 until they are aligned with the second axial slots 105. The nut 106 is then screwed down the thread towards the anchor plate, bringing the flange 107 into engagement with the upper surface thereof, and.

Upon continued tightening of the nut, lifting the shaft away from the potting plug and causing the spacing tabs 32a, 32b to move down the second axial slots 105 and out of alignment with the circumferential slots. The shaft is thereby locked into the potting plug, the mis- alignment of the spacing tabs and the circumferential slots preventing rotation of the shaft in order to release it. Instead, the nut must actively be loosen so as to allow the shaft to drop deeper into the potting plug, thereby returning the spacing tabs into alignment with the circumferential slots and hence enabling release the shaft to be twisted into a release position.

In order to prevent unauthorised release of the shaft, the nut could be provided with some form of anti-tamper interface. A thread locking system such as a prevailing torque device or similar could also he used to make the system more secure in areas of vibration - preventing the coupling shaking loose. For example, a spiralock thread form could be used which gives a free running thread until the nut is torqued up, whereupon the male thread locks on a ramp on the female thread

Claims

Claims 1. A removable post comprising an elongated main body having a

cylindrical aperture extending from at least one end thereof, a shaft concentrically mounted in said cylindrical aperture so as to be axially movable relative to said main body between a first extended position and a second partially retracted position, said shaft having at least one projections of arcuate cross-section provided on an end thereof, the or each projection extending from said at least one end of the main body, terminating in the circumferential direction at an axially extending slot and including a locking slot which intersects with and extends circumferentially from said axial slot so as to form a first part of a bayonet coupling, said shaft further including a radial flange axially spaced apart from said projections and a longitudinally extending slot which extends from said flange towards said projections, wherein an actuating pin extends through said main body and engages in said slot, which pin has a cam surface formed on it which is engaged by said flange such that, upon rotation of the pin, the flange is moved axially relative to the centre of the pin, thereby causing the shaft to move between its extended and partially retracted positions.
2. A removable post according to claim 1, wherein the shaft includes at least two projections of arcuate cross-section, said projections being separated from each other by axially extending slots.
3. A removable post according to claim I or claim 2, wherein the radial flange is formed by a load plate which is mounted on the shaft.
4. A removable post according to claim 3, wherein the pin engages with a lower surface of the load plate which is slidable mounted on the shaft, the post further including spring means and a reaction plate, the spring means engaging with the upper surface of the load plate so as to bias the load plate axially away from a reaction plate and into engagement with the pin, rotation of the pin pressing the load plate towards the reaction plate, so as to compress the spring therehetween, which, in turn urges the reaction plate away from the bottom end of the post, thereby causing the shaft to retract into the post.
5. A removable post according to any of the preceding claims, wherein the pin has a flat formed on it at a first perpendicular distance from its axis of rotation, the remainder of the cross-section of the pin being circular with a radius which is greater than said first perpendicular distance.
6. A removable post comprising a shaft having a recess extending from one end at least partially towards the other end thereof so as to form an annular portion on said one end, a threaded portion provided on the outer surface of the shaft proximate to hut spaced apart from said one end, and a nut provided on the shaft which is threadingly engageable with said threaded portion such that the nut is screwable along the shaft towards and away from said one end, at least one bayonet coupling slot being provided in the shaft extending from said one end, the coupling slot penetrating through the annular wall of the shaft and having a first portion which extends axial from the one end of the shaft, a second portion which extends circumferentially from said first portion partially around the circumference of the shaft, and a third portion which is parallel to but circumferentially spaced apart from said first portion and extends from the second portion axially towards the one end of the shaft, said third portion terminating in a closed end which is spaced apart from said one end of the shaft, wherein, in use, said one end of the shaft engages with an anchor means having a radial member, said radial member engaging in said coupling slot and moving along the first portion upon insertion of the shaft, and along the second portion upon twisting of the shaft following insertion, whereupon the nut is screwed towards the one end of the shaft, bringing it into engagement with the anchor means and lifting the shaft. relative to the anchor means so as to trap the radial member in the third portion of the coupling slot.
7. A removable post according to claim 6, wherein the shaft includes a plurality of coupling slots distributed about is circumferential, the second portion of each extending in the same circumferential direction from the first portion, each slot, in use, engaging an associated one of a corresponding plurality of radial members provided on the anchor means.
8. An anchor for a removable post according to any of the preceding claims, comprising a plate having at least one arcuate through slot formed therein which extends along a circular arc around the centre of the plate and terminates at a radially extending spacing tab, under which an undercut of a bayonet coupling of a post according to the invention is engageable so as to lock said post to said anchor.
9. An anchor according to claim 8, wherein the plate has at least two arcuate slots which each extend through less than 180 degrees along a common circular arc on opposite sides of a common centre, each end of each slot being separated from the proximate end of the other slot by a spacing tab.
10. An anchor according to claim 8 or claim 9, wherein the anchor further includes a hollow insert which, in use, is recessed into the ground and secured in place
11. An anchor according to claim 10, wherein the plate is removably fastened to the hollow insert preferably by means of one of a screw which engages in a threaded opening in a central post formed in the insert and mating male and female threads formed on the plate and pot directly.
12. An anchor according to claim 10 or claim 11, wherein the insert has splines or ribs formed on its outer surface.
13. An anchor according to any of claims 10 to 12, wherein the insert has a central post formed in it which defines, with the inner surface of the outer wall of the insert, an annular chamber, the or each projection engaging in said annular chamber, the annular chamber preferably being sized to be a close fit with the or each projections.
14. Any of the removable posts substantially as herein described with reference to the accompanying drawings.
15. An anchor for a removable post substantially as herein described with reference to the accompanying drawings.