GB2226338A - Support for unwinding cable coil - Google Patents

Abstract

A rotary support for a coreless coil of cable, to unwind the cable, comprises a rotor 1, Fig. 1, having hub 2 bearing telescopic arms 3 ending in stirrups 5 adapted to receive a preformed open coil of cable thereover. The hub mounted on an axle for rotation, and has ratchet 9, 10 cooperating with axle teeth to brake the unwinding coil. Springs 6 seek to extend telescopic arms 3 against latch button 7 adjustably located in one of holes 8. Tubular support frames are shown for the axle. Each latch button, Fig. 8, may comprise buttons 40 urged outwards by leaf spring 41. <IMAGE>

Description

CABLE SUPPORTS The present invention relates to cable supports for use in supporting a preformed coil of cable for rotation to unwind the cable from the coil.

It is common practice to wind up electrical cable on coil formers on which the cable is stored and transported and from which the cable is unwound for use. Some types of electrical cable however are conventionally supplied as an open coil, i.e. a coil not having any coil former. The coil relies for integrity during storage and transporation on the stiffness of the cable and on being wrapped with plastics tape. In particular, mineral insulated calendered cable (commonly known as "pyro") is conventionally supplied in relatively large diameter open coils of this kind. It is the common practice for an electrian using pyro to unreel a length of cable sufficient for the task in hand by walking carrying the coil and unreeling the cable progressively over a substantial length of the scene of the works.The cable cannot be laid out over its desired final run if this involves any obstructions because of the size of the coil. Accordingly, the cable has to be laid out whenever a sufficiently long clear area of floor can be found. The long length of cable which is run out in advance of work commencing on fixing the cable in its desired location is subject to being bent or damaged by other workmen on the site so that a considerable period of time may need to be spent in straightening the stiff cable as it is fitted.

It would be desirable to have a more convenient means of running out a length of cable for use from a coil of such cable.

Accordingly, the present invention provides a cable support for use in supporting a preformed coil of cable for rotation to unwind the cable from the coil, comprising a rotor member adapted to receive a preformed open coil of cable thereover and having means for holding a coil so received thereon, and means for mounting said rotor member for rotation to unwind cable therefrom.

By an "open coil" is meant one which does not have a coil former supporting the turns of the coil.

Preferably, the support further comprises brake means acting between the rotor member and said mounting means for the rotor member to provide sufficient resistance to rotation, at least in a coil unwinding direction, substantially to prevent over-running of the rotor member to throw off cable in the absence of an applied unwinding load. It is envisaged that the cable support will be used by an electrician pulling cable from the coil, e.g. as he walks away from the cable support. There is a danger that when he stops pulling on the cable, the rotor member may continue to rotate by virtue of its acquired angular momentum, so throwing off additional cable which will be at risk of becoming entangled.

The provision of sufficient resistance to rotation of the rotor member with respect to its mounting can ensure that the rotor member stops rotating essentially immediately that the electrician stops pulling cable from the coil.

Preferably, the rotor member comprises means for engaging the inner periphery of said coil in use at a plurality of locations, a hub portion, and means connecting said coil engaging means to said hub portion such that the coil engaging means are movable radially, allowing the coil engaging means to be radially retracted to receive a coil and to be radially extended to hold the received coil.

Preferably, in such a coil support, the coil engaging means comprises a plurality of outwardly open stirrup members connected to said hub portion by telescopically extensible respective radial arms.

Preferably said radial arms are spring loaded to extend.

Preferably also, means is provided for locking each said radial arm at a desired degree of extension or to prevent contraction beyond a desired minium extension. Thus, arms which are not spring loaded may be adjustable by the user to snuggly hold a coil of cable and may be locked at the required radial extension. Arms which are spring loaded may rely upon the spring loading for holding the coil or may in addition be lockable at the required extension.

Alternatively, spring loaded arms may be provided with means which does not lock each arm at a specific extension but when engaged prevents further retraction of the arms whilst allowing spring loaded extension to take up any clearance which might otherwise arise between the coil and the stirrup members if the internal radius of the coil alters as the coil is unwound.

The means for mounting the rotor member for rotation may simply be an axle which can be held by the user in some convenient support such as a pipe vice fitting for a pipe bending machine. Pipe bending machines will commonly be available on site where pyro cable is being used. Alternatively, the means for supporting the rotor member may include a stand on which the rotor member may be mounted for rotation.

Such a stand may conveniently be fabricated from metal tubing and may be adapted to be collapsible for transport and storage.

The invention will be further described with reference to the accompanying drawings in which: Figure 1 is a side elevation of a rotor member of a cable support according to the invention; Figure 2 is a radial elevation of the rotor member of Figure 1; Figure 3 is a side elevation of a mounting means for the rotor member of Figure 1; Figure 4 is a plan view of a support frame in which is located the mounting means of Figure 3; Figure 5 is an end elevation of the support frame of Figure 4; Figure 6 is a side elevation of the support frame of Figures 4 and 5; and Figure 7 is a perspective view of a support bracket for use with a pipe vice to support the mounting means of Figure 3.

Figure 8 is a cross-section on a diameter of the axle of the mounting means of Figure 3 passing through a latch button thereof.

As shown in Figure 1, a rotor member 1 for supporting a preformed coil of cable (not shown) comprises a hub portion 2 bearing four equally spaced radially extending tubular arm portions 3 and a ratchet assembly 9, 10. In each of the arm portions 3 is received as a telescopic sliding fit a second arm portion 4 having at its radially outer end an outwardly open stirrup member 5 in the form of a U lying in a plane perpendicular to the plane of the arms of the rotor member.

The arm portions 3 and 4 are preferably of square section to prevent rotation of the arm portion 4 with respect to the arm portion 3. In the embodiment illustrated, a coil spring 6 is contained within each arm portion 3 and bears against the end of the respective arm portion 4. A latch button 7 is provided on each arm portion 4 and is spring loaded outwardly. Each latch button 7 locates in one of a series of locating holes 8 provided in each arm portion 3, whereby the extension of the arm 3, 4 may be regulated.

The ratchet assembly comprises a truncated triangular frame member 9 mounting a spring-loaded ratchet dog 10 which protrudes inwardly through the hub portion 2 urged by a coil spring 10a acting between the ratchet dog 10 and the frame member 9.

Figure 3 illustrates means for mounting the rotor member 1 in the form of a axle 11 having at each end a spring-loaded latch button 12 similar to latch buttons 7 and having centrally intermediate its ends a larger diameter portion 13 formed with recesses defining therebetween ratchet teeth 14 in a band around its cylindrical periphery. Portion 13 is receivable within the bore of the hub portion 2 of the rotor member whereby the ratchet dog 10 engages in one of the recesses between the teeth 14.

The cable support constituted by the rotor member and mounting means of Figures 1 to 3 may be supported for use in a variety of ways.

Figures 4 to 6 illustrate a support frame for the cable support comprising tubular triangular end frames 20 linked by tie bars 21. The base of each triangular end frame 20 passes through a short tubular member 22 attached cross-wise to the end of each tie bar 21 whereby a hinged connection is formed between the tie bars 21 and the triangular end frames 20. At the apex of each end frame 20 is provided a short tubular member 23 for receiving one end of the axle 11 of the mounting means shown in Figure 3, a hole being provided through the wall of each tubular member 23 to receive the latch button 12-of the respective end of the axle.

Outwardly latch buttons 24 are provided on the base of one triangular end frame 20 to engage, upon rotational alignment, with holes in the short tubular members 22 by which the tie bar 21 are hinged to the end frame 20. The effect is that when the one end frame is lifte from its folded down position on top of the tie bars, it will latch in an operative raised position, ready to receive one end of the axle 11.

The manner of utilisation of the cable support shown in Figures 1 to 3 with the support frame shown Figures 4 to 6 is as follows. To mount a coil of pyro-cable, the coil is first freed of any wrapping.

The telescopic arms of the rotor member shown in Figure 1 are contracted sufficiently to allow the stirrup members 5 to be fitted within the inner periphery of the coil and are then extended to grip the coil securely. The mounting means shown in Figure 3 is passed into the hub portion 2 of the rotor member either before or after one end of the axle 11 is located in a respective tubular member 23 of the support framework. The other end of the axle 11 is then located in the other tubular member 23. Cable may then be drawn from the coil as desired. The action of the ratchet dog 10 riding over the teeth 14 of the mounting means of Figure 3 provides a braking action sufficient to prevent over-running of the rotor member when cable is no longer being actively pulled from the coil.The ratchet mechanism also provides a convenient means of preventing lateral movement of the rotor member on the axle 11.

An alternative method of mounting the axle 11 is shown in Figure 7. On many occasions where pyro is being installed, a pipe bending machine of the kind having a tripod base and pipe bending head will be available on site. Such machines include a pipe vice for gripping a pipe. The support illustrated in Figure 7 has an L-shaped tubular principal member 30 having one end 31 intended to be received in the pipe vice of a pipe bending machine and an open other end 32 for receiving one end of axle 11. A support arm 33 extends downwardly from the angle member 30 and is intended to locate on one leg of the pipe bending machine support tripod by means of a fork 34. The rotor member 1 may be mounted on the axle 11 and utilised in the manner previously described.

Each latch button, described above may take the form shown in Figure 8, i.e. may comprise a pair of opposed head portions 40 penetrating the wall of the tube containing the pin and linked by a U-shaped flat metal leaf spring 41 biassing the head portions outwardly.

It will be appreciated that whilst the invention has been described with reference to the particular embodiments illustrated, many variations and modifications thereof may be made within the scope of the invention. In particular, the brake mechanism employed need not be in the nature of a ratchet mechanism but may for instance involve friction material provided on an annular face of a collar mounted on the axle 11 to rub against the hub portion of the rotor member. The telescopic arms 3, 4 need not be spring-loaded and if spring-loaded need not necessarily employ any latching mechanism to enable the arms to be locked at a particular extension.

Claims (8)

1. A support for use in supporting a preformed coil of cable for rotation to unwind the cable from the coil, comprising a rotor member adapted to receive a preformed open coil of cable thereover and having means for holding a coil so received thereon, and means for mounting said rotor member for rotation to unwind cable therefrom.

2. A support as claimed in Claim 1, wherein the support further comprises brake means acting between the rotor member and said mounting means for the rotor member to provide sufficient resistance to rotation, at least in a coil unwinding direction, substantially to prevent over-running of the rotor member to throw off cable in the absence of an applied unwinding load.

3. A support as claimed in Claim 1 or Claim 2, wherein the rotor member comprises means for engaging the inner periphery of said coil in use at a plurality of locations, a hub portion, and means connecting said coil engaging means to said hub portion such that the coil engaging means are movable radially, allowing the coil engaging means to be radially retracted to receive a coil and to be radially extended to hold the received coil.

4. A support as claimed in Claim 3, wherein the coil engaging means comprises a plurality of outwardly open stirrup members connected to said hub portion by telescopically extensible respective radial arms.

5. A support as claimed in Claim 4 wherein said radial arms are spring loaded to extend.

6. A support as claimed in Claim 4 or Claim 5, wherein means is provided for locking each said radial arm at a desired degree of extension or to prevent contraction beyond a desired minimum extension.

7. A support as claimed in Claim 5, wherein the spring loaded arms are provided with means which when engaged prevents retraction of the arms whilst allowing spring loaded extension to take up any clearance which might otherwise arise between the coil and the stirrup members if the internal radius of the coil alters as the coil is unwound.

8. A cable support for use in supporting a preferred coil of cable for rotation to unwind the cable from the coil substantially as hereinbefore described with reference to.and as illustrated in the accompanying drawings.