GB2038109A - Improvements in or relating to cable ladders - Google Patents

Abstract

A cable ladder comprises a pair of longitudinal members 12 with transverse spaced rings 13, each longitudinal member defining a pair of spaced, oppositely facing channels 18 extending along its length, and a connector plate 21 for each end of a member, which is to be connected to a corresponding adjacent end of a member of a further cable ladder, one end of each connector plate 21 being slidably engaged in the channels 18 of respective members and projecting from the member to engage in the end of the adjacent member. <IMAGE>

Description

SPECIFICATION Improvements in or relating to cable ladders This invention relates to cable ladders.

According to the present invention there is provided a cable ladder having a pair of longitudinal members with transverse spaced rungs extending between them to support cable runs, each longitudinal member defining a pair of aligned, spaced, oppositely facing channels for slidably receiving a connector plate such that, in use, the connector plate lies normal to the plane of the ladder rungs and projects from the member for engaging, in use, in corresponding channels in an adjacent member of a further cable ladder.

The channel may extend along the whole length of its respective member.

The cable ladder may further comprise at least one connector plate. At least one of the connector plates, may comprise a plate having a pair of aligned notches formed in opposite sides thereof such that the plate can be bent along a line extending between the notches.

Alternatively at least one of the plates may have a pair of arms lying in a common plane.

In this latter case the angle between the arms may be 90 , or 120 or 135 or 150 or any other desired angle.

Each member may have a further channel extending along its length for receiving one end of each rung.

Specific embodiments of the invention will now be described with reference to the following drawings in which: Figure 1 shows a plan view of an assembly of cable ladders located in a part of a room; Figure 2 shows a sectional view through a cable ladder of Fig. 1 along the line ll-ll; Figure 3 is an elevation of an assembly of cable ladders and shows its relative position to other surface units; Figure 4 is a plan view of a connector plate; Figure 5 is a perspective view of an end of a longitudinal member of the cable ladder of Fig. 2 showing the connector plate of Fig. 4 located therein; Figure 6 is a plan view of a second form of connector plate; and Figure 7 is a plan view of a third connector plate.

It is known to support cable runs on assemblies of cable ladders or perforated trays. In general cable ladders are used for heavy duty cables whilst perforated trays are used for lightweight cables. Cable ladders, which comprise a pair of longitudinal members with transverse spaced rungs extending between them, are connected together by means of fish plates which are bolted to adjacent ends of longitudinal members. The cable ladders are normally provided with the bolt holes predrilled but if for any reason a non-standard length of cable ladder has to be used and therefore the cable ladder has to be cut, fresh holes have to be drilled. Such cutting is almost inevitably required whenever the cable ladder assembly changes direction either in a horizontal or vertical plane. Perforated trays are often joined together by interfitting ends or by sleeves slidable on their upstanding edges.If a perforated tray assembly has to change direction in a vertical or horizontal plane either a special "angle" units are used or the perforated plate has to be cut. Cutting the perforated plate can take a considerable time because of the quantity of material which needs to be cut. Fig. 1 shows a number of cable ladder lengths connected in an assembly generally indicated at 11.

Referring to Figs. 1 and 2, each cable ladder length 10 comprises a pair of longitudinal members 1 2 with transverse spaced rungs 1 3 extending between them. Each longitudinal member 1 2 is formed as an aluminium extrusion. Each member 1 2 has an upstanding web 1 4 with parallel inwardly facing end walls 15, 16. Each of end walls 15, 16 is formed with an inwardly extending projection 1 7 which extends along its length. Projections 1 7 and web 1 4 together define a pair of aligned vertically orientated spaced opposite facing channels 1 8 which extend along the length of respective longitudinal member 1.

Each end wall 1 6 is slotted at its edge along its length to form a horizontally orientated channel 1 9 for receiving a respective end of each rung 13. The ends of rungs 1 3 are welded to respective longitudinal members 1 2 by welds 20.

Each rung 1 3 is generally T-shaped in cross section along that part of its length which lies intermediate the longitudinal members 1 2 with the vertical web 1 2a of the T off-set. The edges of the cross portion of the T of rungs 1 3 are appertured along its length, as shown in Fig. 5, so that plastic clips (not shown) can be held without slipping on the rungs 1 3 and retain cables to the rungs 1 3.

It will be appreciated that in assembly the cable ladders can be constructed by extruding longitudinal members 12, disposing a pair of longitudinal members 1 2 facing each other with their channels 1 9 aligned and sliding rungs 1 3 into channels 1 9 to spaced locations. Welds 20 can then be formed.

Fig. 4 shows a,connector plate 21. Connector plate 21 comprises a rectangular aluminium plate which has opposed notches 22 formed at the bisectors of its longest sides. As will be seen in Fig. 5 connector plate 21 is dimensioned so that it can be slidably engaged in the ends of channels 1 8 of a longitudinal member 1 2. When it is desired to connect two cable ladder lengths 10 together in a straight run a connector plate 21 is initially inserted in the mouths of channels 1 8 at one end of a cable ladder length with the connector extending into the channels 1 8 up to the notches 22 and then the further cable ladder length 10 is adjoined to the first cable ladder length by sliding it onto the projecting portions of the connector plates 21.So that respective halves of the connector plate 21 lie in respective channels 1 8 of adjacent longitudinal members of the aligned cable ladder lengths.

If it is desired to connect two cable ladder lengths, which lie in the same horizontal plane, at an angle to each other then the longitudinal members of each cable ladder length are cut so that the adjacent ends of longitudinal members 1 2 of cable ladder lengths 10 can engage with the cable ladder lengths lying at the required angle and the connector plates 21 which are to be inserted between the cable ladder lengths are then bent along a line extending between their notches 22 such that the requisite angle is formed between the halves of the connector plate laying on either side of the line.

Referring to Fig. 1 the connector plates 21 at area A have been bent to 90 whereas connector plates 21 at area B have been bent to 45 .

It will be appreciated that when cable ladders are being erected in factories or warehouse establishments pipes or ducts for other surfaces will very often lie in the desired path of the cable ladder assembly. For example, pipe 23 and duct 24 in Fig. 1. In these instances the cable ladders have to be connected at an angle, in order to go around the pipe or duct.

Because the channel 1 8 extends along the whole length of each longitudinal member 12, wherever the longitudinal member is cut either for length or to form an appropriate angle there is a mouth of the channel 1 8 in which the connector plate 21 can be inserted.

Thus, merely by cutting with a hacksaw through the relatively thin extrusions of longitudinal members 1 2 it is possible to form any desired angle between horizontally extending cable ladder lengths without having to machine the cable ladder lengths in any way in order for them to be connectable.

The cable ladder lengths 10 can be hung on the ceiling of the room through which they pass or alternatively on the walls by brackets one of which is shown at 27.

Fig. 3 shows an elevation of a cable ladder assembly in which a number of cable ladder lengths 10 have been connected together so that they lie in a variety of horizontal or vertical planes in order to avoid such obstructions as pipes 23 and duct 24. The cable ladder lengths 10 are of exactly the same construction as those shown in Figs. 1 and 2 and are connected together by connector plates. However, in this instance the connector plates are formed with arms lying in a common plane. By varying the angle between the arms the angle between the cable ladder lengths 10 can be varied.

Fig. 6 shows a 90 angle connector plate 25 whilst Fig. 7 shows a 120 connector plate 26. These connector plates are also shown in the assembly of Fig. 3. It will be appreciated that connector plates with any other angle between their arms can be formed and it is anticipated that connector plates having angles of 1 35 and 1 50 between their arms would also be provided in addition to those illustrated in Figs. 6 and 7.

It will be appreciated that by removing a section of one longitudinal member 12, a T junction of cable ladder lengths can be formed with the upright part of the T connected into the cut longitudinal member 1 2 by means of two 90 bent connector plates 21.

It will further be appreciated that where, in cutting a cable ladder length, a rung is lost the gap formed by the missing rung can be filled by the user sliding a new rung into the opposed channels 1 9. Rung 27 in area A is an example of such a rung.

In some cases the engagement of connector plates 21 into channels 18 should provide sufficient engagement between the connector plates 21 and respective longitudinal members 12, without the use of fastening members such as bolts. However in certain circumstances, and particularly to ensure electrical continuity between the ladder lengths, it may be desirable to crimp, or to swage and indent the connector plate 21 to the web 14 of at least one of its respective members 1 2 e.g. as at 28 in Fig. 5, in which case this may be carried out using crimping or swaging pincers.

Claims (11)

1. A cable ladder having a pair of longitudinal members with transverse spaced rungs extending between them to support cable runs, each longitudinal member defining a pair of aligned, spaced, oppositely facing channels for slidably receiving a connector plate such that, in use, the connector plate lies normal to the plane of the ladder rungs and projects from the member for engaging, in use, in corresponding channels in an adjacent member of a further cable ladder.

2. A cable ladder as claimed in Claim 1, wherein each channel in each member extends along the length of its respective'member.

3. A cable ladder as claimed in Claim 1 or Claim 2 further comprising at least one connector plate.

4. A cable ladder as claimed in Claim 3, wherein at least one of the connector plates comprises a plate having a pair of aligned notches formed in opposite sides thereof such that the plate can be bent along a line extend ing between the notches.

5. A cable ladder as claimed in Claim 3 or Claim 4 wherein at least one of the connector plates has a pair of arms lying in a common plane.

6. A cable ladder as claimed in claim 5, wherein the angle between the arms is 90 .

7. A cable ladder as claimed in claim 5, wherein the angle between the armsis 120 .

8. A cable ladder as claimed in claim 5, wherein the angle between the arms is 135 .

9. A cable ladder as claimed in claim 5, wherein the angle between the arms is 150 .

1 0. A cable ladder as claimed in any one of the preceding claims, wherein each member has a channel extending along its length for receiving one end of each rung.

11. A cable ladder substantially as hereinbefore described with reference to and as illustrated in Fig. 2 and Fig. 5 or Figs. 2 and 5 as modified by Fig. 6 and 7.

1 2. An assembly of cable ladder as claimed in any one of Claims 3 to 1 wherein the or each connector plate is fastened to at least one of its respective member.

1 3. An assembly as claimed in Claim 1 2 wherein the or each connector plate is crimped to at least one of its respective members.

1 4. An assembly as claimed in Claim 1 2 wherein the or each connector plate is swaged and indented to at least one of its respective members.

1 5. An assembly comprising two cable ladders as claimed in any one of the preceding claims, wherein each connecting member is slidably engaged in adjacent ends of adjacent members of the two cable ladders.

1 6. A method of joining cable ladders as claimed in claim 3 or in any one of claims 4 to 10 as dependant on claim 3, comprising the steps of cutting at least one longitudinal member of the cable ladders to be joined and slidably engaging connector plates in adjacent ends of the longitudinal members of the cable ladders to be joined.

1 7. A method of joining cable ladders substantially as hereinbefore described with reference to the accompanying drawings.