IE44812B1 - Improvements in or relating to cable glands - Google Patents

Abstract

1526696 Cable glands F LACKINGER 14 April 1977 [19 Nov 1976] 15639/77 Heading H2E A cable gland comprises an armour spreading member having a tubular portion 9 extending from a frustoconical end portion 8, the portion 9 having at its free end at least one radially outwardly extending stop formation 10, a differential nut and sleeve 1 receiving the free end of the tubular portion, and a clip 7 axially located in the sleeve 1 and arranged so as to co-operate with the formation 10 and retain the armour spreading member captive to the sleeve 1. A seal 3 may be situated within the sleeve 1 to grip the inner insulation of a cable, and an outer seal 21 may also be employed.

Description

THIS INVENTION relates to cable glands and j in particular, to cable glands having an armour clamp comprising a truncated conical armour spreading cone and a co-operating conical’surface on a'thimble portion of the gland. ’ There is known a cable gland of the above type wherein the armour spreading cone is held captive whilst allowing rotation thereof relative to a differential nut Or sleeve which co-operates with the thimble portion of the gland to urge the armour spreading cone towards the cooperating surface of the thimble portion. The cone is held / ··· captive in the prior art devices by either splaying the free end of a sleeve extending away from the cone so that the splayed end is located inwardly of an inwardly directed flange on the differential nut or sleeve, or alternatively, by deforming the end of the sleeve or differential nut inwardly into a groove near the larger diameter end of the cone. A further alternative which has been proposed is to provide an outwardly directed flange at an end of a sleeve carrying the cone with the outer periphery of the flange screw threaded to IO co-operate with a' complementarily screw threaded inwardly directed flange. However, this involves two screw threading operations and also does not positively prevent the removal of the cone from the differential nut or sleeve.

Apart from manufacturing difficulties, and the cost of manufacture, the known arrangements do not allow for a fire proof inner seal to be installed easily since most regulations provide that such inner seal cannot be installed from the end of the cable gland remote from the cone. The reason for this is that any joint on the inside of the inner seal would provide a passage for gas to enter or.escape.

It is the object of this invention to provide a cable gland having a captive armour spreading cone which is simple to manufacture and yet allows for the installation of a fire proof inner seal from the end nearer the cone. -344811 In accordance with this invention there is provided a cable gland comprising an armour spreading cone wherein the armour spreading cone has a tubular portion extending away from the cone and at least one outwardly directed stop formation at the free end thereof, a differential nut or sleeve receiving the end of the tubular portion and associated outwardly directed stop formation, a clip whereof at least a part extends inwardly from the inner surface of the differential nut or sleeve and means for locating the clip axially within the differential nut or sleeve so that it acts to retain the tubular portion captive by co-operation with the stop formation.

Further features of the invention provide for the I clip and said means to be such that the tubular portion of the cone together with the stop formation can be introduced past the clip after its installation' by resilient deformation of the clip; for· the differential nut or sleeve to house a seal adjacent the end of the tubular portion carrying the stop formation; for the thimble portion of the cable gland to include a captive rotatable member providing a conical surface for co-bperation with the armour spreading cone; and for the said means to be a groove in the inner surface if the differential nut or sleeve in which case the clip is conveniently a substantially circular resilient clip. The thimble portion of the cable gland may embody an outer seat of. known design if required. / ... -4V The invention will now be further described with reference to the accompanying drawings in which :Fig. 1 illustrates in sectional elevation a differential nut housing a seal and . , carrying a captive armour spreading cone; Fig. 2 illustrates in similar elevation a cable gland embodying the invention but without an outer seal; and, Fig. 3 illustrates in similar elevation a cable gland having both inner and outer seals.

As illustrated in Fig. 1 a differential nut 1 of substantially conventional design, has an outer screw threaded portion 2 which houses an inner seal 3 of dimensions suitable for use as a flame and gas proof inner seal. The opposite end portion 4 of the differential nut is externally screw threaded in the usual way to enable it to be connected mechanically to a junction box or the like. t The mouth of the portion 2 of the differential nut is provided adjacent the end thereof with a groove 5 in the inner surface, the groove extending around the entire inner periphery of the mouth. The mouth is provided with a tapered lead-in 6 for a clip in the form of a split spring-steel ring 7 / ... -5to facilitate its being installed in the groove. The crosssectional dimensions of the ring and groove are such that the I ring can be expanded outwardly into the groove against its normal resilience to a position in which it is nearly flush ' with the inner wall of the differential nut. The undeformed dimension of the ring is such that it will always project appreciably into the mouth of the differential nut whilst being retained axially by the groove.

An armour spreading cone 8 having a tubular portion 9 extending axially away from the cone has a stop formation in the form of an. outwardly directed flange 10 at its free end. The outer dimensions of the flange are such that it may be forced past the ring by deforming the latter outwardly into ί · the groove. The ring snaps back into position after this movement and thereby holds the cone captive relative to the differential nut.1 The flange is provided with a tapered lead-in surface 11 ,to facilitate its introduction past the ring and the end is bevelled as indicated by numeral 12 at its inner edge to co-operate with an end of the seal 3. xn use, as the differential nut is screwed into a thimble portion 13 (see Fig. 2) the end of the tubular portion engages the seal to compress it axially onto the inner . . / ... -64 4 812 sheath 14 of an armoured cable whilst the armour wires 15 are clamped between the cone and a co-operating conical surface associated with the thimble. Preferably, the said co-operating surface is provided on a ring 16 held captive in the thimble but being rotatable relative thereto: This construction ensures that the -armour wires are not twisted or deformed during tightening of the gland when, and if, the cone is rendered non-rotatable relative to the differential nut.

As illustrated in Fig. 3 the thimble portion 17 may be provided with an extension 18 having a screw threaded flange 19 at its free end. A sleeve-like nut 20 co-operates with this flange to define a space for a outer seal 21 which, in .use, is compressed axially by tightening the sleeve-like nut. The latter is also preferably held captive on the flange by deforming its free end 22 inwardly to prevent it from being removed completely from the flange 19.

It will be understood that whether or not the cable gland has an outer seal, the gland may be supplied as only.two separate parts, one being the differential nut and cone assembly, and the other being the pre-assembled thimble portion. This has the advantage that parts cannot be omitted from the cable gland during installation thereof.

Claims (3)

1. A cable gland comprising an armour spreading cone wherein the armour spreading cone has a tubular portion extending away from the cone and at least one outwardly directed stop formation at the free 5 end thereof, a differential nut or sleeve receiving the end of the tubular portion and associated outwardly directed stop formation, a clip whereof a part extends inwardly from the inner surface of the differential nut or sleeve and means for locating the clip axially 10 within the differential nut or sleeve so that it acts to retain the tubular portion captive by co-operatiop with the stop formation.

2. A cable gland as claimed in claim 1 in which the clip and said means are such that the tubular portion 15 of the cone together with its stop formation can be introduced past the clip after the latter's installation as a result of resilient deformation of the clip. / ... -9-14 812

3. A cable gland as claimed in claim 2 in which the end of the tubular portion carrying the stop formation is tapered to provide a lead-in surface for co-operation with the clip. 5 4. 5. 6. 20 7. A cable gland as claimed in any .one of. the preceding claims in which the differential nut or sleeve houses an inner seal adjacent the end of the said tubular portion carrying the stop formation. A cable gland as claimed in claim 4 in which the inner edge of the end of the tubular portion carrying the stop formation Is bevelled for co-operation with the inner seal. A cable gland as claimed in any one of the preceding claims in which said means is a groove in the inner surface of the differential nut or sleeve and the clip is a substantially circular clip having a part thereof extending into the groove and a part thereof located inwardly of the inner surface of the differential nut or sleeve to co-operate with said stop formation. A cable gland as claimed ih claim 6 in which there is provided a tapered lead-in surface between the groove and adjacent end of the differential nut or sleeve. / ... -1044812 5 9. 5 9. 10. 10. 15 11. 15 11. A cable gland as claimed in any one of the preceding claims in which the thimble portion includes a captive rotatable member providing a conical surface for co-operation with the armour spreading cone. A cable gland as claimed in any one of the preceding claims in which there is provided an outer seal on the end of the thimble portion remote from the differential nut or sleeve. A cable gland as claimed in claim 9 in which the outer seal comprises a sleeve-like nut co-operating with a screw threaded portion of the thimble to compress an outer seal therebetween, the sleeve-like nut being held captive on.said thimble to prevent its complete removal therefrom. A cable gland substantially as herein described with reference to any one of Figs. 1, 2 or 3 of the accompanying drawings.