Cable tray

Details Cable tray Cable tray

1999-08-31

2001-11-06

Reichard, Dean A. (Department: 2831)

Electricity: conductors and insulators

Conduits, cables or conductors

Single duct conduits

C174S095000, C174S097000, C174S09900B

Reexamination Certificate

active

06313405

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates generally to support systems used in the construction industry, and more particularly to ladder-type cable trays used to support runs of cable (e.g., bundles of electrical wiring and the like).
Conventional ladder-type cable trays comprise spaced apart parallel and/or concentric side rails and a series of spaced-apart rungs extending transversely between the rails, the rails and rungs typically being of extruded aluminum alloy or other suitable formed metal. It has been the conventional practice to secure the rungs to the side rails by welding. Some cable tray systems use screw fasteners as disclosed in U.S. Pat. No. 5,580,014 to Rinderer (incorporated herein by reference).
Cable trays come in various widths and have straight sections and curved sections with various bend angles (e.g., 45°, 90°) and radii of curvature. To provide for ease of design, construction and installation, these dimensions and configurations have been standardized. In a curved (arcuate) section of cable tray the rungs extend, preferably radially, between the side rails and need to be accurately positioned to control spacing between the rungs. If the rungs are attached to the rails by mechanical fasteners (e.g., screws), accurate rung spacing requires accurately spaced apertures for receiving the fasteners. Heretofore, the spacing between these apertures has varied according to the width of the tray, its radii of curvature and its bend angle. This variation in spacing reduces manufacturing flexibility and efficiency and increases cost. Therefore, for this type of cable tray there is a need for a construction which uses a standardized fastener hole spacing which will accommodate a wide variety of tray sizes and configurations.
SUMMARY OF THE INVENTION
Among the several objects of this invention may be noted the provision of improved ladder-type cable trays of the type where the rungs are attached to the rails by mechanical fasteners; the provision of such cable trays wherein the spacing between the fastener apertures is standard to accommodate various sizes and configurations of cable trays and components; the provision of such a tray design which will permit increased manufacturing flexibility and efficiency; the provision of such a tray design that reduces the amount of tooling needed to produce the fastener apertures; the provision of a cable tray that can be suspended at various angles by bracket mounting components positioned entirely outside of the cable fill area to reduce snag points; the provision of a cable tray that has a row of apertures in the laterally extending top flanges of the side rails for ready mounting of fixtures and a cover on the cable tray and for receiving vertical support rods to suspend the tray; the provision of a cable tray section having a bottom floor panel in which the sharp end edges of the floor panel are covered to prevent damage to the contents of the tray; the provision of a cable tray assembly that comprises cable tray sections in end-to-end relation that are joined by splice plates that can be fastened in place in a manner that does not place snag points in the cable fill area; and the provision of a cable tray which is designed to avoid snagging, cutting, or other types of damage to items carried by the tray.
A first aspect of the present invention involves the provision of a cable tray section that has inside and outside rails each with a web and an arcuate section. The rails are concentric about a center point and the inside rail arcuate section is curved on an inside arc and the outside rail arcuate section is curved on an outside arc. There is a row of inside rail apertures in the web of the arcuate section of the inside rail starting adjacent one end of the arcuate section of the inside rail and continuing at substantially equally spaced intervals to a position adjacent an opposite end of the arcuate section. There is also a row of outside rail apertures in the web of the arcuate section of the outside rail starting adjacent one end of the arcuate section of the outside rail and continuing at substantially equally spaced intervals to a position adjacent an opposite end of the arcuate section. The spacing between the inside rail apertures is substantially identical to the spacing between the outside rail apertures. The apertures in the inside and outside rails are so located that radial lines passing through the center point and certain of the apertures in the inside rail also pass through corresponding apertures in the outside rail. Rungs extend between the arcuate sections of the inside and outside rails at intervals spaced along the rails. Each rung is aligned with a radial line passing through the center point and corresponding apertures in the inside and outside rails. Fasteners extend through respective apertures in the inside and outside rails into opposite ends of each rung for securing the rung to the rails.
Another aspect of the present invention involves the provision of a cable tray rail for use in a cable tray of the type comprising a plurality of spaced apart side rails and a floor extending between the side rails for supporting a plurality of cables in a cable fill area defined by the side rails and floor. The cable tray rail comprises an elongate metal beam having a central generally vertical web with opposite first and second sides and opposite first and second ends. The beam includes a generally horizontal top flange extending laterally from at least one of the first and second sides of the web, and a generally horizontal bottom flange extending laterally from at least the second side of the web. A plurality of spaced apart apertures are in the top flange.
The present invention is also directed to a cable tray section that includes a pair of rails in side-by-side spaced apart relation. The rails have webs with inside surfaces and outside surfaces with the inside surfaces facing toward one another and the outside surfaces facing away from one another. There is a row of spaced apart rail apertures in each of the webs along the length of the webs adjacent a lower portion of the webs. Rungs extend between and are secured to the rails, the rungs having upper surfaces positioned above the rows of rail apertures. At least one bracket is secured to each of the rails and has a portion extending laterally outwardly away from a respective outside rail surface. Fasteners cooperate with the brackets and extend through respective rail apertures for securing the brackets to the rails. A support member is secured to each of the brackets and suspends the cable tray section in an elevated position.
Another aspect of the present invention involves the provision of a cable tray section having a pair of spaced apart elongate side rails with webs defining side walls of a cable tray interior. The webs have top and bottom portions. An end rung extends between and is secured to the rails adjacent one end of the cable tray section and adjacent the lower edges of the rail webs. The rung has a groove extending along the length thereof adjacent a top portion of the rung and opening into the cable tray interior away from said one end of the cable tray section. A floor extends between the side rails adjacent the lower edges of the rail webs and between opposite ends of the cable tray section, the floor and portions of the webs above the floor define a cable fill area. The floor is adapted for supporting cables in the cable fill area and has an end margin received in the groove for supporting the floor in place.
An additional aspect of the present invention involves the provision of a cable tray assembly that includes a pair of cable tray sections each comprising a pair of spaced apart side rails having first and second opposite ends and a plurality of spaced apart rungs extending between and secured to respective side rails. Each side rail comprises a web with top and bottom edges and inside and outside surfaces and at least one web aperture adjacent the bottom edge and at least one of the first and second ends. Ea

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