This invention relates to shelf brackets or cantilever brackets of the type having a fixing end for attachment of the bracket to a mounting so that the bracket will extend cantilever fashion away from the mounting. The other end may simply be free, or it may be connected for example to a hanger member if additional support is required.

We are particularly interested in these brackets in their application to cable tray and cable ladder installations, the brackets serving to support the cable trays or brackets which in turn are for the receipt of electrical cables and service pipes and the like, as indeed is well known.

Because of the construction and novel nature of the bracket according to the invention, it has particular application to cable ladder and cable tray installations, but it is to be pointed out that it is not at this time intended to limit the application to such use.

Cable tray shelf brackets or cantilever arms as they are known are required because they are used in environments where corrosion may occur, to be resistant against such corrosion, and to this end they may take various forms. For example they may be in stainless steel, or they may be in steel which is mill galvanised, or they may be in steel and then hot dip galvanised.

In cable ladder systems, the cantilever arms are attached to upright channel members which form the mountings. These channel members are box shaped in cross-section but are slotted along one side to receive fixing bolts and typically a pair of fixing bolts will pass through the mounting end of the cantilever arm and into the slot thereby fixing the

cantilever arm in position.

Alternatively, the mounting end of the cantilever arm may have a preformed plate having a single aperture for receiving a mounting bolt, and a curved tang which is adapted to locate in the slot so as to simplify mounting in that only a single fixing bolt is required. This form of cantilever arm however has only limited use insofar as it must be used with a channel member whereas the known cantilever arm with a pair of apertures can be used for mounting to another form of mounting, for example a flat mounting surface.

The present invention seeks to provide a shelf bracket usable as a cable tray cantilever arm which comprises a metallic plate blank of suitable configuration bendable to define the cantilever arm (overlapping or adjacent portions being welded if required) and wherein at the mounting end there is a flat mounting plate portion provided with a mounting aperture for a fastening bolt, and also a portion defining a tang which can be bent out of the plane of the mounting plate portion for example to engage in the slot of a channel member to which the cantilever arm is mounted by means of the fastening bolt.

It will be understood that the question of whether or not the tang portion is bent out of the plane of the plate portion depends upon the mounting to which the cantilever arm is to be fixed. If the mounting is a channel member, then the fitter can deflect the tang portion on site, for example by hammering it against the ground or the like to bend it out of the plane of the plate portion. If the cantilever arm is to be fixed for example to a flat surface such as a wall, then the tang portion can remain in the plane of the plate portion, and to this end the tang portion may be provided with an aperture for receipt of a fixing screw which may

simply serve the purpose of preventing the cantilever arm from rotating on the mounting bolt in use. Alternatively, the tang portion may be provided on site with such fixing aperture.

The cantilever arm may be made up of the rear plate portion, a tapered side plate portion extending from one edge of the rear plate portion, a top plate portion extending from the top edge of the side plate portion, a reinforcing tab at the mounting end of the top plate portion and in abutting contact with the rear plate portion and welded thereto, and finally a reinforcing marginal portion at the lower edge of the side plate portion.

The top plate portion may be provided with a series of apertures enabling the cantilever arm to be fixed by screws or the like to a cable tray or cable ladder or other shelf supported thereon. The layout of the apertures in the top plate portion and the configuration of same may be as which is based on our British Patent Application No. 9019495.2 so that with the use of the cable tray as described in the said application, with the unique aperture pattern in the base thereof in combination with the cantilever arm with its aperture pattern, there will be the capability of fixing the cable tray to the cantilever arm regardless of the position of the cantilever arm longitudinally relative to the cable tray, all as explained in said co-pending application.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, wherein:-

Fig. 1 is a plan view of a sheet metal blank adapted to be formed into a cantilever arm according to the embodiment of the invention;

Fig. 2 shows a cantilever arm formed from the blank of Fig. 1; and

Figs. 3 and 3A show how the cantilever arm may be fixed to a channel member or a flat surface.

Referring to the drawings, in Fig. 1 a blank of mild steel is shown, and indicated on the drawing in dotted lines are the lines along which the metal is folded in order to form the cantilever arm of Fig. 2.

It will be seen that the blank comprises a side section 10 of tapering configuration defining a top edge 12 and a bottom edge 14. Connected along the top edge is a top portion 16 having an aperture pattern therein, which will be described hereinafter, and along the bottom edge is a reinforcing strip 18.

At the larger end, which is the mounting end, is a mounting plate section 20, and finally to the end of the top plate section 16 is a strengthening tab 22.

To form the cantilever arm from the blank of Fig. 1, the blank is folded along lines 12 and 14 so that the top section and reinforcing strip lie at right angles to the side plate portion 10. The reinforcing tab 22 is then bent at right angles to the top plate portion, the bending being along line 24, and finally the plate is bent along line 26 so as to make the mounting plate portion 20 disposed at right angles to the side plate portion 10 and to lie in face to face contact with the mounting plate portion to which it is welded by means of welding 27 (Fig. 2).

It is noted that the mounting plate portion 20 and the reinforcing tab 22 are provided with apertures 28, 30, which

become aligned when the bracket is assembled to provide a single mounting aperture for receiving a mounting bolt 33 (Fig. 3) or the like enabling the bracket as shown in Fig. 2 to be mounted to a slotted channel member 32 of conventional configuration. The channel member 32 is provided with a slot 34 through which the bolt 33 passes.

To the lower end of the mounting plate portion is provided a reduced width tang portion 36 which is provided with a fixing aperture 38.

When the cantilever arm of Fig. 2, on site, is to be fixed to the channel member 32, the tang portion is bent as shown in dotted lines out of the plane of the mounting plate portion so as to extend into the slot 34, in which position it prevents the cantilever arm from rotating about the axis of the fixing bolt 33 which fixes the cantilever arm to the channel member.

Should it be that the cantilever arm is to be fixed to a flat surface, then the tang portion is left in the plane of the mounting plate portion as shown in Fig. 4 and whilst a similar fixing bolt 33 is used for fixing the cantilever arm to the flat surface, a smaller restraining fixing member such as a screw 42 is passed through the fixing aperture 38 in the tang portion 36 so as to serve the purpose of restraining the cantilever arm from rotating about the axis of the fixing bolt when in use.

Attention is drawn to the aperture pattern in the top portion of the cantilever arm. This aperture pattern is designed and arranged so as to cooperate with the aperture pattern in the cable tray 40 which is shown in dotted lines in Fig. 2, and which is to be supported by the cantilever arm. These aperture patterns are such that regardless of the position of

the cantilever arm longitudinally of the cable tray, there will be sufficient registration between the aperture pattern in the cantilever arm and the aperture pattern in the cable tray to ensure that either fixing bolts can be passed through both components for the fixing of the tray relative to the arm, or spring fixing clips as described in our British Patent Application No. 9019495.2 can be inserted through the cable tray and cantilever arm again for the fixing of the cable tray relative to the arm.

The canilever arm shown in Fig. 2 is a mild steel and hot galvanised dipped component, but the invention can be applied to other constructions.