GB2273824A - Cable Ladder - Google Patents

Abstract

A cable ladder has a pair of parallel metal side walls 22 (24) separated by a plurality of spaced apart rungs 10. Each rung is formed by a respective metal strut extending perpendicularly between the side walls, and each strut has a flat face at each end of which there is provided a pair of oppositely directed co-planar ears 18, 20 and a tongue 12 which extends between the ears. The tongue and ears extend perpendicularly to the flat face. Each side wall includes integral pockets 26 formed by die punching sections of said side walls so as to provide aligned slits top and bottom through which the tongues can be pushed to retain the struts in position while the tongues are being secured to the displaced panels by, for example, being riveted (32, 34, 36 Figure 6) press joined or bonded thereto. There is also provided a kit of parts for making such a cable ladder. <IMAGE>

Description

Title: Cable ladder Field of invention This invention concerns cable ladders and in particular a method of construction which permits a strong structure to be formed without the need for substantial internal tooling for effecting the joints.

Background to the invention UK specification 2,255,454 discloses a cable ladder in which some of the struts have end extensions which protrude in alignment with the face of the strut and are fixed to out-turned edges of the channel section side walls and other of the struts (typically alternately positioned along the ladder) have up-turned end extensions which after being fitted through slots in the side walls of the ladder, sit flush and in contact with the external faces of the side walls. The extensions are secured by rivetting, welding or the like, to the edges and faces of the side walls.

It is an object of the present invention to provide a simpler form of construction than that of the aforementioned specification.

Summary of the invention According to the present invention in a cable ladder having parallel metal side walls and a plurality of spaced apart rings formed by metal struts extending perpendicularly between the side walls, each strut has a flat face and is formed at each end with two oppositely directed coplanar ears between which extends a tongue, all of which respectively extend perpendicular to the said flat face, and each side wall includes integral pockets formed by die punching sections of the said side walls to form displaced parallel panels therein joined at opposite ends to the rest of the wall but otherwise defining aligned slits top and bottom through which the tongues can be pushed, to retain the struts in position while they are rivetted, press joined, bonded or otherwise secured to the displaced panel.

Preferably the adjoining ears are forced into contact with the inwardly facing surfaces of the side walls by the interaction of the tongue and the slits between the displaced panel and the side wall.

Preferably additional fixings are provided between the side walls and the ears. Again rivetting, press joining, bonding or any other method of joining may be employed.

The joining of the tongue and the side wall (via the displaced panel) prevents lateral movement between a strut and a side wall, while the joining of the ears to the side wall prevents any twisting of a strut about its elongate axis relative to the side wall.

A very strong joint between strut and side wall is thus provided.

An advantage of this arrangement is that where the joining of the tongue and ears to side walls is to be achieved by the application of a force (such as an impact force as in press forming) whilst it is necessary to insert an anvil behind the ears and the displaced panel, the striking tool operates wholly from outside the side walls of the ladder.

It is a further advantage of the arrangement that the interengagement of tongues and ears, holds the two side wall members in position ready for joining. The assembly thus requires minimal holding jigs and tools.

The invention also lies in a method of constructing a cable ladder comprising the steps of: (a) punching out and partially separating panels from the web-of each elongate side member of the ladder so as to define pockets having aligned top and bottom slits, at spaced positions along the length of the side member, (b) forming by perpendicularly bending flanges at opposite ends of an elongate strut designed to fit between and space apart a pair of said side members, to form tongues at each end which are thereby adapted to engage in pockets on opposite sides of the ladder the one in the side member on one side, and the other in the side member on the other side of the ladder, (c) forming at the ends of each said strut pair of oppositely directed coplanar ears adapted to engage the inside surface of a side member on either side of a tongue receiving, and (d) fitting said struts between two side members so as to form a self-supporting sub-assembly.

The method may also involve the securing of the ears and the tongues to the walls and panels respectively by means of press joining or riveting or the like.

The invention also lies in a kit of parts as aforesaid which when joined together form a cable ladder comprised from elongate parallel spaced apart side members and regularly spaced apart perpendicular rungs formed by struts joined at their ends to the side members in the manner as aforesaid.

The invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a top view of a strut; Figure 2 is an underside view of the strut; Figure 3 is an end view of the strut; Figure 4 is a perspective view of one end of the strut; Figure 5 is a perspective view of part of a side wall to which the strut as shown in Figures 1-4 can be fitted; Figure 6 is a side view of part of a side wall showing the strut in position; amd Figure 7 is an end view of the assembled ladder.

Detailed description of the drawings In the drawings each strut comprises a bridging plate 10 having downturned ends forming tongues 12 and sides 14, 16 which themselves have end extensions in the form of flaps (or ears) 18, 20 which are bent outwardly to be coplanar.

The tongues 12 and flaps 18, 20 are also substantially coplanar.

Each strut is secured at opposite ends to two elongate side members 22, 24. To this end pockets are formed in the side walls by die punching out panels, such as 26 (see Figure 5) each of which is joined at its ends to the rest of the side member 22 (24) but is separated from the side member top and bottom to define aligned slits 28, 30. The tongues of the strut such as 12 can be pushed down through the slits 28, 30 to occupy the position shown in Figure 6 and in this condition the flaps 18, 20 press against the inside of the side member on either side of the panel 26.

Press joining or rivetting at 32, 34 and 36 secure the panel 26 to the tongue 12 and the flaps 18, 20 to the web of the side member 22.

The side walls 14, 16 of the strut are each bent through a right angle to form opposed flanges 38, 40 which do not join but define a central elongate gap 42 on the underside of the strut. Each strut can therefore be thought of as having a top face and a bottom face, and although not shown, can be fitted alternately to face top face up, top face down, etc, along the length of the ladder.

Claims (9)

Claims

1. A cable ladder comprising parallel metal side walls and a plurality of spaced apart rungs formed by metal struts extending perpendicularly between the side walls, wherein each strut has a flat face and at each end, a pair of oppositely directed coplanar ears between which extends a respective tongue, the ears and tongue extending perpendicularly to said flat face, and wherein each side wall includes integral pockets formed by die punching sections of the said side walls to form displaced parallel panels therein joined at opposite ends to the rest of the wall and defining aligned slits top and bottom through which the tongues can be pushed, to retain the struts in position while the tongues secured to the displaced panel.

2. A cable ladder according to claim 1 in which at least one pair of ears is forced into contact with inwardly facing surfaces of the side walls by the interaction of the pespective tongue and displaced panel.

3. A cable ladder according to claim 2 in which additional fixings are provided between the side walls and the ears.

4. A cable ladder according to claim 3 in which the additional fixings are also provided between the tongue and the ears, wherein, where said additional fixing has been achieved by the application arrangement a force by a striking tool, the tongue and ears are so positioned that the additional fixing was achieved by operating the striking tool wholly from outside the side walls of the ladder.

5. A cable ladder substantially as described herein with reference to, and as illustrated in, the accompanying drawings.

6. A method of constructing a cable ladder the method comprising the steps of: (a) punching out and partially separating panels from the web of each of a pair of elongate side members of the ladder so as to define pockets having aligned top and bottom slits, at spaced positions along the length of the side member, (b) forming, by perpendicularly bending flanges at opposite ends of each of a plurality of elongate struts designed to fit between and space apart said side members, tongues at each respective end of each strut the tongues on each strut being adapted to engage in pockets on opposite sides of the ladder the one tongue in the side member on one side, and the other tongue in the side member on the other side of the ladder, (c) forming at the ends of each said strut pair of oppositely directed coplanar ears adapted to engage the inside surface of a side member on either side of a tongue and (d) fitting said struts between two side members so as to form a self-supporting sub-assembly.

7. A method according to claim 6, further comprising the step of securing the ears and the tongues to the walls and panels respectively.

8. A method substantially as described herein with reference to the accompanying drawings.

9. A kit of parts for a cable ladder which kit when assembled forms a cable ladder according to any of claims 1 to 15.