GB2197183A - Racking system - Google Patents

Abstract

A racking system for the fitting out of warehouses, distribution centres and the like, comprises a plurality of post members (10) of square section with apertures in the side walls thereof, pairs of said post members being secured together by rung bars (26) to form ladder frames, and the system also including cross connecting members (32,46) comprising beams with brackets at the ends thereof said brackets having tongues which can be located in the apertures on the posts, and the system further including support bars (34) which are slotted transversely so that the ends can be inserted in apertures in the posts and the slots engage with the edges of the post apertures. The support bars 34 may extend through the post members to provided an expandable racking system and may terminate in brackets attachable to walls. The aperture/tongue system may be used to support cantilever beams or shelves or to support rails for garments. <IMAGE>

Description

SPECIFICATION Racking system This invention relates to a racking system, being a system of posts and bars to form a framework for the support of various items and for use in connection with storage, and/or live suspension items, i.e. the suspension of items so they can be moved on support rails and other related purposes.

There are of course many racking systems in existence and these take numerous forms, but all are provided with upright posts on cross connecting means. In some cases the cross connecting members take the form of shelves.

Generally speaking racking systems of this nature involve the utilisation of bolts and screws for the effective construction of same and the utilisation of bolts and screws involves the utilisation of various complicated brackets and fixings.

In the garment industry, there is a need for large scale storage installations as well as the need for the provision in such installations of the so-called "live" storage rails which are rails for receiving garment hangers or trolleys carrying garment hangers, the hangers normally supporting garments. These trolleys or hangers can therefore be slid or rolled on live rails for the effective movement of same in large storage and distribution warehouses.

There is also a need for the racking systems for these warehouses to be capable of assembly and dismantling readily, and the present invention seeks to provide a system suitable for achieving this objective.

The invention in its preferred form also seeks to achieve novel forms of connecting members and posts and, with only slight addition to the type of components used, capability of the system being fixed or jacked to surrounding walls or structures to provide extra security and strength.

With these and other objectives in mind, the invention provides a racking system comprising: (i) tubular post members having apertures in the walls thereof; and (ii) cross connector beams comprising brackets on the ends thereof, tongues provided in said brackets for engagement in the apertures in said post members whereby the cross connector beams can be engaged with spaced upright cross members to maintain same in upright spaced condition without requiring fixing screws.

Preferably, the racking systems includes; (iii) support beams comprising tubes with transverse slots therein and spaced from the ends thereof, said ends being engageable in the apertures in the post members, and the support beams lowered so that the post member walls at the bottom of said apertures can engage in said slots; said cross connector beams and support beams being of the same length so as to be capable of extending between a pair of parallel upright post members.

It will be understood from the above that the posts, cross connecting members and support members can be assembled readily and without the use of any fixing screws or other fixing devices.

When the racking system comprises pairs of the post members, it is simply a matter of positioning the cross connecting members.to that the tongues of the brackets in the respective ends thereof engage in post apertures, and the support beams can be slotted into position between the post members to provide hanging rails for garment hangers or the like or to provide shelf support means.

In a preferred construction, the racking system comprises ladder frames being frames made up of spaced support members with rung bars extending between and welded to said post members. By so providing such frames, rigid three-dimensional racking can be constructed in that the cross connector beams and the support beams can be positioned between the post members of the respective frames.

The ladder frames may be made up of three or more equally spaced post members secured by said rung bars, the post members being contained in a common plane.

The cross connector beams may be of several types, and in a first type the cross connector beam has L-shaped brackets secured to the ends thereof, one face of the L-shaped bracket being welded to the end of the beam, and the other face being provided with tongues which are punched or pressed therefrom and are adapted to engage in the apertures in the post members. When the post members are of square section, as in the preferred embodiment, the L-shaped brackets will lie around two sides of the post members, the tongues being engaged in the apertures in one side of the post member and then being connected thereto by the connector beam being lowered relative to the post members so that the tongues catch behind the post member wall.

In a second type of cross connector beam the ends have plates welded thereto, and said plates are provided with said tongues being pressed and punched therefrom. Such cross connector beams engage in apertures in the face of the post member in relation to which the cross connector beam lies at right angles.

It is preferred that the apertures in the post members are elongated and at one end are straight edged and at the other end are curved edges. When this construction is used, it is preferred that the support beams which slot into the apertures be elongated in cross section with curved ends and the support beams preferably are of tubular form. The support beam will be dimensioned so that its end can be slotted into an aperture in the post member and then support beam lowered so that its end slot engages the wall of the post member at the straight end of the post member aperture.

The racking system may have anciliary components such as feet plates which are located at the bases of the post members in order to stabilise the post members when the racking is in use, and another feature comprises the provision of a cantilever bar which can be connected to the post members so as to extend outwardly to form a cantilever arm i.e.

the outer end of the cantilever being free for example for the support of the live storage rails.

The cantilever beams preferably have brackets with pressed tongues therein so that they can be connected to the post members, again by engagement with the tongues in the post member apertures.

There may also be provided jacking beams being beams which are adapted to be passed through the apertures in the post members and having on at least one end a plate which can be jacked against a wall or other surface in order to rigidify the positioning of the bracket. Such jacking beams are used in conjunction with locking brackets which lock the beams, when in jacked position, to the post members. Such locking bracket may comprise a U-shaped member having apertures in the limbs thereof so that the jacking beam passes through the limb apertures in addition to passing through the post apertures, and in the base of the locking bracket is a threaded bore containing an adjusting screw which is tightened to lock the jacking beam to the post when the jacking beam is in the required position.

Furthermore, there may be provided fixing beams which are of similar construction to the jacking beams and are secured to post members in similar fashion but which at the ends which are located adjacent the wall, are provided with plates having apertures therein whereby fixing screws pass through the apertures to fix the framework to a surrounding wall or other fixed surface such as the inside of a transport container or vehicle body.

The system may be provided with additional member to increase its flexibility. For example, a small shelf support plate may be provided with a single tongue pressed therefrom, and a portion of the plate displaced out of the remainder of the plane of the plate. With this plate the tongue is inserted in one of the apertures in one of the post leaving the displaced portion spaced from the post. The plate is of the same width as the post, and therefore the displaced portion can form a support means for the edge of a shelf extending between posts which are spaced horizontally in two directions, the shelf being of a type comprising a plate with a down turn flange around the periphery thereof. The flange can engage behind the displaced portion of the shelf plate on each of four posts whereby the system can provide shelving support.

In an alternative construction for providing shelving support, shelf support bars are provided with mounting plates on the ends thereof, said mounting plates being adapted to lie against a first face of a post, and having turned portions which extend partially around an adjacent face of the post, said turned portions having hooks for hooking into the post apertures at the sides thereof. A similar plate on a similar shelf bar can be hooked into the same pair of apertures and the shelf bars will therefore lie in the same horizontal plane whereby continuous shelving ridging posts can be provided. The shelf bars may be angle irons having horizontal sections for supporting shelves placed thereon.

An embodiment of the racking system according to the invention will now be described, by way of example, with reference to the accompanying drawings, wherein: Figure 1 is a perspective view of a post member of the racking system according to the present invention; Figures 2 and 3 are respectively a side and sectional elevation of a ladder frame including posts as shown in Fig. 1; Figures 4 and 5 are an end view and side view of the detail ringed in Fig. 3; Figure 6 is a side view of a three post ladder frame of the racking system according to the invention; Figure 7 is a perspective view illustrating how the racking according to the present invention can be constructed; Figure 8 is a perspective view of one form of cross connecting member according to the invention;; Figures 8A and 8B are a side and sectional view of an alternative form of crossed connecting member of the racking system according to the invention; Figures 9 and 10 illustrate two possible cross sectional forms of the cross connecting beams and other beams of the racking system according to the present invention; Figure 71 illustrates in perspective elevation how the cross connecting beam in Fig. 8 is connected to a post member; Figure 12 illustrates in perspective elevation another form of cross connecting beam of the racking system according to the invention; Figures 12A and 12B illustrate in side view and in sectional elevation a fixing beam of the racking system according to the invention; Figure 13 illustrates how the cross connecting beam of Fig. 12 of the fixing beam of Figs. 12A and 12B is fixed to a post member; ; Figures 14 and 15 illustrate in perspective elevation how the support beams are connected between the post members; Figures 16 and 17 illustrate in perspective elevation and sectional elevation how the jacking beams and fixing beams of the racking system according to the invention are locked to the post members; Figures 18 and 19 illustrate in detail the construction of each support beam; Figure 20 illustrates in side elevation one form of cantilever beam of the racking system according to the invention; Figure 21 illustrates an alternative form of cantilever beam for the racking system according to the present invention; Figure 22 illustrates how the racking system may be used for the support of a live support rail; Figures 23 and 24 illustrate a coupling bracket which is used when the racking is to have tubular rails secured thereto according to Fig. 1;; Figure 25 shows a post and a shelf mounting plate in exploded perspective view; Figure 26 shows the post and mounting plate of Fig. 25 in sectional elevation and when coupled together; Figure 27 shows a pair of shelf bars with mounting plates thereon and engaging a post for the provision of shelf supports; and Figure 28 is a sectional elevation of the arrangement shown in Fig. 27.

Referring to the drawings, in Fig. 1 there is shown a post member 10 of the racking system according to the invention. The post member 10 is a square sectioned mild steel tube and is provided with apertures 10A and 10B in the sides thereof as shown. The apertures 10A are in the sides 12 and 14, whilst the apertures 10B are in the sides 16 and 18.

Each of the apertures 10A and 10B is of the same shape which is in the form of a cathedral window in that the aperture is elongate in the length direction of the member 10 and has a straight base 20 and a curved top 22.

The apertures 10A in the sides 12 and 14 are in alignment whilst apertures 10B in sides 16 and 18 are also in alignment, but as shown in Figs. 1, the apertures 10A are interspaced with the apertures 10B as regards the length direction of the post 10.

Th apertures 10A and 10B may be provided throughout the length of the respective sides 12, 14, 16 and 18, or only so far along the length of any side as a particular installation dictates.

In Fig. 2 there is shown a ladder frame 24 which comprises a pair of the post members 10 rigidly interconnected by means of mild steel rung beams 26.

As shown in Figs. 4 and 5, the rung beams 26 are circular in section and are welded to the post members 10 by the welds 28. As many rung beams as are required may be used and the rung beams are arranged to be parallel to each other and to lie horizontally when the ladder frame is in use.

Racking assemblies according to the invention can use ladder frames and/or the individual post members shown in Fig. 1.

As shown in Fig. 5, the rung beam 26 meets a side of the post member 10 between the apertures in that side so that in fact the rung beam 26 will be in alignment with the apertures 10A or 10B on the sides adjacent the side to which the beam is welded.

Fig. 6 illustrates an alternative form of ladder beam which comprises three post members 10 secured by two pairs of rung beams 26. The post 10 are contained in a common plane and again the rung beams are welded to the post members.

Figs. 1, 2 and 6 also show that the post members 10 are provided with foot plates 30 which are optional components of the system of the present invention. These foot plates may be a loose fit in the bottom ends of the post members 10 or may be securely fixed thereto. The foot plates furthermore may have apertures for the fixing of the foot plates to the ground on which the racking system stands.

Fig. 7 shows a simple form of racking assembly according to the invention which comprises a pair of ladder frames 24 of the type shown in Fig. 2, and the frames are connected by means of cross connecting beams 32, and support beams 34, thereby to form three-dimensional racking so that articles can be supported thereby, for example by being suspended on the support beams 34. In specific installations, the racking system will have most extensive use when large areas are to be fitted out with the racking system, in which case the racking system will be extended many times in both directions. Fig. 7 is therefore given only to illustrate the principle of construction, and to indicate how simple it is to assemble the racking system according to the invention.

Fig. 8 shows one of the cross connecting beams 32 and it will be seen to comprise a cross connecting bar 34 to the ends of which are welded similar brackets 36. Each bracket 36 is L-sectioned and comprises a first arm 38 which is secured to the end of bar 34 by welding 40, and a second arm 42 which lies at right angles to the arm 38, and is provided with inwardly pressed tongues 44 of the form shown. To connect this connecting beam to the post members 10, for example in the racking assembly in Fig. 7, it is simply a matter of engaging the tongues 44 of the respective brackets 36 in the apertures 10A or 10B of the post and then by sliding the cross connecting beam downwardly so that the tongues 44 engage behind the walls of the post members adjacent the straight edge portions 20 of the apertures 10A, 10B as shown clearly in Fig. 11.

Figs. 8A and 8B show an alternative form of cross connecting beam in which the bar 34 is connected nearer to the top of the arm 38 of the bracket 36. Figs. 8A and 8B also show that the cross sectional shape of the bar 34 is somewhat eliptical in having straight sides and curved ends. The cross sectional shape of the bar 34 is not of particular importance to the present invention, and Fig. 9 shows that this bar can have a circular shape rather than the approximate eliptical shape shown in Fig. 10.

It will also be noted that the connector beam of Figs. 8A and 8B is of different hand from that shown in Fig. 8. This means that the connector beams can be connected to the posts so as to lie in alignment with each other horizontally, the two arms of the bracket 36 of one beam lying on two sides of the adjacent post member 10 and the two arms of the other cross connecting bracket lying on the other two sides of the post member 10.

Another form of cross connecting beam is shown in Figs. 12 and 13 and the operation of same will be understood readily from the previous description given in relation to Figs.

8 and 11. The beam of Fig. 12 has a bar 46 to which are welded brackets 48 being in the form of flat plates provided with tongues 50 pressed therefrom. The tongues 50 are similar to the tongues 44 of the Fig. 8 embodiment, and the tongues fit into the post member 10 in similar fashion, and as shown in Fig. 13. It will be understood that the tongues 44 are pitched similarly to the pitching between the apertures 10A and 10B, and also that the pitching between the apertures 10A and 10B is equal.

Figs. 12A and 12B show a fixing beam which comprises a bar 52, to one end of which is connected a bracket 54 in the form of a plate similar to the plates shown in Fig.

12. The tongues 56 are again provided to enable the plate to be connected to a post member in the manner shown in Fig. 13. The plate 54 is provided on one end only of the beam 52 and the other end may be plane as shown so that the bar 52 forms a cantilever support member, or it may be provided with a means enabling the end of the bar 52 to be fixed for example to a wall or other permanent surface.

Before referring to Figs. 14 and 15, reference is first made to Figs. 18 and 19 which show one of the support beams 34 shown in Figs. 7. This support beam is simply a mild steel tube of the section shown in Fig. 19 i.e.

the section is elongate so as to provide straight side portions 58 and curved ends 60 and 62.

Inwardly of each end the tube 34 is slotted as shown at 64, and the distance from the tube end to the adjacent slot 64 is the same at each end and is less than half the width of the post member 10. Additionally, the distance 66 between the slots 64 is substantially equal to the distance between the brackets 36 of cross connecting bar 32 and the distance between the plates 48 of the cross connecting bar 46.

At the side 62 of the support beam 34 there is a chamfer or lead in 68 to the slot 64 enabling the ready coupling of the support beams 34 to the post 10 as now described in relation to Figs. 14 and 15.

In Figs. 14 and 15 a support post 10 is shown as are two of the apertures 10A and 10B. Two support beams 34 are shown as are their end slots 64.

The fitting of the ends of the beams 34 to the post 10 will be understood clearly from consideration of Figs. 14 and 15. The beam 34 in each case is inserted through the aperture 10A or 10B until the slot 64 comes into alignment with the straight lower edge 20 of the aperture 10A, 10B when the beam 34 is simply lowered so that the edge 20 engages slot 64 as shown in Fig. 15, keeping the support beams 34 in position.

The racking system may be provided in those posts adjacent the surrounding walls or other fixed surfaces of the area in which the racking is contained, with jacking or fixing beams 70 of the cross sectional shape similar to that of the support beams 34. Such jacking or fixing beams 70 are usually made to extend through two adjacent support posts 10 and one end is provided with a fixing or jacking plate 72. The apertures 74 in plate 72 are for enabling the fixing of the plate to an adjacent wall or other fixed surface.

Figs. 16 and 17 show a locking device for locking the beam 70 in adjusted position, and the locking device comprises a U-shaped bracket 76 having limbs 78 and a base 80.

The limbs 78 are provided with apertures 82 through which the beam 70 passes whilst the base 80 is provided with threaded bore 84 which receives a threaded screw 86 provided with a hand turnable wheel 88. The operation of the locking device will be understood clearly from consideration of Fig. 17. The beam 70 passes through the apertures 82 in the bracket 76 of which the limbs lie on opposite sides of the post 10 so that the beam 70 also passes through a pair of aligned apertures 10A, 10B of the said post member 10.

If the screw 88 is tightened in this position, the bracket 76 is forced away from the post 10 and the beam 70 prevents this movement away from the post whereby the beam becomes locked between the post and bracket.

When the screw 86 is loosened, then the beam 70 can slide freely through the bracket 76 on the post 10 whereby it can be moved to adjusted fixing or jacking position.

The cantilever beam shown in Fig. 20 comprises simply two bar lengths 90, 92 which are welded together in the region 94, and each of the bars 90, 92 has at one end a plate 96, 98, which lie in the same plane as shown, and each is constructed similarly to the plate of the cross connecting member shown in Figs. 12 and 13 in that it has a pair of tongues 100 pressed therefrom which are spaced at the same spacing as the apertures 10A, 10B, and the spacing between the plates 96 and 98 is a multiple of the spacing between the apertures 10A, 10B of the post member 10 so that the cantilever beam shown in Fig. 20 can readily be mounted on any post member in the same fashion as the plates shown in Figs. 12 and 13.

Another form of cantilever mounting plate is shown in Fig. 21. This comprises a plate 102 of the configuration shown defining two arms 104 and 106 which extend outwardly from a central plane 108. Welded to the plate 102 in the region of the central plane 108 is a mounting plate 110 which is provided with a single tongue 112 of the form previously illustrated in Figs. 13 and 14. A hole 114 is drilled in the centre line of the assembly so as to extend through the plate 102 and plate 110 for receipt of a self turning screw for a purpose to be explained.

At the extremities of the arms 104 and 106 are mounting shelves 116 and 118 for receiving a live storage rail. The storage rail is for connection to these curved shelves by means of screws which pass through apertures 120 in the shelves.

This mounting plate can be mounted on a post member by engaging the tongue 112 in one of the apertures 10A, 10B of the post member followed by the insertion of a self tapping screw into the hole 114 and by tightening same. The tightening of the screw -causes the plate member 102 to be jacked away from the post member thereby locking the tongue firmly in position.

Fig. 22 illustrates part of an assembly of the racking system according to the invention. A post member 10 is clearly shown as are the rung beams 26. A cross connecting beam 32 is shown as being mounted on the post 10 and extending in a direction opposite to that from the rung beams 26. Two further cross connecting beams 32 are shown as being mounted on the post at different positions and extending at right angles to the first mentioned beam 32 to show how the cross connecting beams can be used to extend the racking in two mutually orthogonal directions.

The first mentioned beam 32 is shown as carrying a G-bracket 122 which carries a live support rail 124 on which garment hangers or live trolleys may be carried.

Figs. 23 and 24 show a plate 124 which is wider than the plates of the cross connector shown in Figs. 12 and 13 and has a pair of coupling tongues 126, 128 along a central line 130 of the plate whereby the plate may be mounted on a post in the same manner as the plates illustrated in Figs. 12 and 13.

Adjacent the edges of the plate 124 are apertures 132 which are adapted to receive bolts whereby a bracket holding a tubular rail may be bolted thereto. The bracket may be a semi-cylindrical shell arranged with its axis horizontal.

Referring to Figs. 25 and 26, a post 10 is shown as are two apertures 10A and 10B. In addition a shelf mounting plate 150 is shown, and it will be seen that this plate has a displaced portion 152 which is displaced relative to a remaining portion 154 having a tongue 156 which is similar for example to the tongues 44 shown in Fig. 8 displaced therefrom.

It will be understood that the plate 150 can be mounted on the post by engaging the tongue 156 in an aperture 10A or 10B, and then sliding the plate downwards so that the tongue 156 engages behind the wall of the post 10 as shown clearly in Fig. 26. When the mounting plate 150 is in position, a shelf shown in chain dotted lines at 158 in Fig. 26 can be mounted on the plate 150 by having a peripheral rim 160 thereof engaged behind a portion 150. To mount the shelf 158, there would have to be four of the said plates 150 provided on respective posts provided at the corners of a square or rectangular corresponding to the size of the shelf 158.

The arrangement shown in Fig. 27 provides a means whereby continuous shelving may be mounted on shelf bars. In Figs. 27 a post 10 is shown in chain dotted lines, and in two apertures 10B thereof are mounted two plates 160 and 162 which are in fact of opposite hand and are symmetrical about the centre line of the post 10. Each plate comprises a main portion 164 which is welded to a shelf bar 166 and a turned position 168 having hooks 170, 172 formed therein as shown.

The hooks 170 and 172 engage in the edges of the apertures 10B whilst the plates 164 lie against adjacent sides of the post 10. With this arrangement, the shelf bars 166 can be arranged in horizontal alignment, it being understood that the other not shown ends of the shelf bars 166 have similar mounting plates 164 mounted on adjacent posts 10.

The bars 166 are of L-shaped section as shown so as to provide horizontal floor portions 174 on which selves may rest. It will be appreciated that there have to be parallel shelf bars 166 to support the other sides of such shelf plates. The shelf plates are indicated in chain dotted lines by reference numeral 176.

Fig. 28 shows the arrangement in cross sectional elevation, and it will be seen that the hooks 170 of the respective plates 164 are spaced apart although engaging in the apertures 10B so as to leave a space for the insertion of for example a cladding plate if it is desired to erect cladding between adjacent posts. Such a cladding plate may be simply a metal plate with hook portions displaced therefrom for engaging in the apertures 10B.

The racking system as described is ex tremely flexible in its utilisation. It can be used to provide three dimensional framework simply for storage purposes with the support beams either forming beams for the suspension of hangers, or providing a means for supporting shelf surfaces, or the framwork can be adapted for example as shown in Fig. 22 to support a live suspension rail to which suspended articles can be moved. The framework can be extended for long distances i.e. of the order of 200 or 300 metres by the use of ladder frames, cross connecting beams and the support beams.

Additional facilities include the capability of anchoring the framework to a wall or other fixed surfaces and other purpose designed fittings can be arranged to be mounted on the posts such as for example the plate illustrated in Figs. 23 and 24.

Claims (12)

1. A racking system comprising: i) tubular post members having apertures in the walls thereof; and ii) cross connector beams comprising brackets on the ends thereof, tongues provided in said brackets for engagement in the apertures in said post members whereby the cross connector beams can be engaged with spaced upright cross members to maintain same in upright spaced condition without requiring fixing screws.

2. A racking system according to Claim 1, including support beams comprising tubes with transverse slots therein and spaced from the ends thereof, said ends being engageable in the apertures in the post members, and the support beams lowered so that the post member walls at the bottom of said apertures can engage in said slots, said cross connection beams and support beams being of the same length so as to be capable of extending between a pair of parallel upright post members.

3. A racking system according to Claim 1, including ladder frames comprising spaced ones of said post members connected by rung bars extending between and welded to said post members.

4. A racking system according to claim 1 or 2, wherein the cross connector beams comprise beams having L-section angle brackets on each end, each angle bracket having spaced tongues pressed from one arm of the bracket, the other arm of the bracket being welded to the end of the beam.

5. A racking system according to claim 1 or 2, wherein the cross connector beams comprise beams having flat plate brackets welded to the ends of the beams, each plate having spaced tongues pressed therefrom.

6. A racking system according to claim 1, wherein the apertures in the post members are elongated and at one end are straight edged, and at the other end are curved edged, and said support beams comprise tubes of a section comprising straight sides and curved ends.

7. A racking system according to claim 5, wherein the slots in said support bars extend halfway through the bars.

8. A racking system according to claim 1, wherein the system includes locking brackets each comprising a U-shaped member in which a post member can be located, apertures in the limbs of the locking bracket, a threaded bore in the base of the locking brackets, locking screws in the bases of the locking braclc- ets, said apertures in the locking brackets being for receiving the ends of the support beams so that the ends of the said support beams can be locked in the post members.

9. A racking system according to claim 1, wherein the post members are square sectioned tubes and apertures in the post members are arranged to be in alignment in the opposite faces of the posts but offset in adjacent faces of the posts.

10. A racking system according to claim 8, including jacking devices comprising a jacking bar which can pass through apertures in said posts and said apertures in said locking brackets so that when the jacking bars are adjusted to jacking position by being slid through the locking brackets and apertures in the post members, the jacking bars can be locked in position.

11. A racking system according to Claim 1 including shelf mounting plates comprising plates having tongues therein adapted to engage in the apertures of the posts, said plates having displaced portions which, when the tongues of the plates are engaged in the apertures in the posts, lie spaced from the post wall surfaces to enable a shelf to be engaged between the plate and the post.

12. A racking system according to Claim 1, including shelf bars comprising bars with mounting plates at the ends thereof, each mounting plate comprising a main portion connected to the end of the bar, and a turned portion lying at right angles thereto, said turned portion having hooks for engagement in the post apertures in one of the faces of the post at right angles to the face against which the main portion of the mounting plate engages.