Joints and connections – Rod end to transverse side of member – Utilizing opposite sides of member
Patent
1998-07-13
2000-12-05
Browne, Lynne H.
Joints and connections
Rod end to transverse side of member
Utilizing opposite sides of member
403329, 4034081, F16B 2107
Patent
active
061557412
DESCRIPTION:
BRIEF SUMMARY
This invention relates to fastening devices, for the connecting of two members together, and the invention has particular application to the connecting of rungs and rails of cable management ladders which are manufactured from synthetic plastic materials in particular glass reinforced plastics materials and of which the rails and rungs are formed by extrusion or pultrusion. These fastening devices require to provide a strong coupling, as the cable management ladders are often suspended at high levels and can carry large amounts of weighty cables and pipes. Also although not intended workmen will often use the ladders for supporting their weight for example in cases of emergency or need.
GRP cable ladders comprise side rails and rungs, and the rungs, of the type to which the present invention relates, are tubular members which are "closed" insofar as in cross section they have continuous peripheries or in other words they are not provided with any longitudinal slots, or are provided with such slots or are channel sectioned in which case they will also be provided with peripheral anti-splaying holding bands or ferrules, making them in effect "closed", and the expression "closed" as used hereinafter is intended to cover all such arrangements. The invention has particular and exclusive application to the connecting of these tubular members to other members. In relation to the cable ladders therefore reference will be made to closed rungs which will be understood to be constructed as described above.
The side rails to which the closed rungs are connected in GRP cable ladders typically are of channel section and comprise a base portion and side flanges. There may be one or more intermediate flanges between the side flanges to split the rail into several cavities. In the constructed ladder; the ends of the rungs abut the inner base surfaces, and fixing of the rungs is effected by boring a fixing aperture through at least one of the side or intermediate flanges, and opposed locations through the rung end, and then a fixing bolt is passed through the aligned apertures and is securely by means of a nut and a washer. The head of the bolt will typically lie within the rail cavity. As mentioned above, these fastenings require to provide secure connections which can take a significant load.
Fixing in this manner is in fact slow, because in any cable management system there may be a considerable length of cable ladder to be installed, which will involve a large number of rungs. Additionally, the bolt heads can be the cause of snagging when lengths of cable ladder are moved from place to place on site. Finally, the nuts also form projections which can interfere with the positioning of the cables to be supported by the ladder and can snag with such cables. The main disadvantage however is the length of time it takes to apply the bolts, and there is an ancillary disadvantage that it is not always easy to apply the nuts, because the inner ends of the bolts may be inaccessible.
In the prior art there are a number of fixing or fastening devices, and for example various screw fastening devices are disclosed in UK patents Nos. 1142763, 1083032, 1028684 and 993633. Generally, the devices disclosed in these patents, with the exception of 1083032, are sheet metal fabrications which provide a means into which a screw or bolt can be tightened, to for example attach an electrical cable or a panel, or assemble cabinets. Patent No. 1083032 also discloses a device for connecting panels, but provides a plastic nut which is in two parts which are connected by a hinge portion, and the parts are hinged together to form the nut which can then be inserted in a panel hole for the receipt of a bolt.
The plastic nut of patent No. 1083032 is quite unsuitable for the application of the present invention, and the fabricated sheet metal devices of the other specifications would not provide enough strength in the fastening to be suitable for cable ladders. Additionally, the sheet metal fixing devices are not as convenient to use as the devices accordi
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Browne Lynne H.
Cottingham John R
Mita (UK) Ltd
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