TRADUCTION NON-DISPONIBLE

ELECTRIC CABLE GLAND WITH FIRE-PROOF SEAL

Abrégé anglais

ABSTRACT OF THE DISCLOSURE
A cable gland of the type having an armour spread-
ing cone held captive relative to a differential nut or
sleeve so as to provide for relative axial and angular
movement of the cone relative to the nut or sleeve and
wherein the armour spreading cone may be urged in use towards
a co-operating thimble portion having a complementary conical
surface for co-operation with the cone to clamp armour wires
therebetween. The differential nut or sleeve receives a
tubular extension carried by the armour spreading cone which
is maintained axially within the differential nut or sleeve
by co-operation of a clip acting effectively to prevent
passage of the tubular extension out of the differential
nut or sleeve by rendering the clip fixed relative to either
the extension or differential nut or sleeve and co-operable
with a stop formation on the other member. The clip is
particularly adapted for easy installation and conveniently
comprises a spring steel ring.

Revendications

The embodiments of the invention in which an exclusive
property or privilege is claimed are defined as follows:-
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 end thereof, a 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 sleeve and
means for locating the clip axially within the sleeve so
that it acts to retain the tubular portion captive by co-
operation 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 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.
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.
4. A cable gland as claimed in claim 1 in which the
sleeve houses an inner seal adjacent the end of the said
tubular portion carrying the stop formation.
5. 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.
6. A cable gland as claimed in claim 1 in which said
means is a groove in the inner surface of the 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 sleeve to co-operate
with said stop formation.
7. A cable gland as claimed in claim 6 in which
there is provided a tapered lead-in surface between the groove
and adjacent end of the sleeve.
8. A cable gland as claimed in claim 1 in which the
thimble portion includes a captive rotatable member providing
a conical surface for co-operation with the armour spreading
cone.
9. A cable gland as claimed in claim 1 in which there
is provided an outer seal on the end of the thimble portion
remote from the sleeve.
10. 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.

Description

2~90
This inventlon relates to cable glands and 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 co-operating
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 diff-
erential 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 co-operate with a
complementarily screw threaded inwardly directed flange. How-
ever, this involves two screw threading operations and also
does not positivçly pr~vent 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 pro-
vide a passage for gas to enter or escape.
It is the object of this invention to provide acable 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.

~1~2~
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 for-
mation at the free end thereof, a 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 sleeve and means for
locating the clip axially within the 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
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-operation 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.

~l~Z~390
The invention will now be further described with
reference to the accompanying drawings in which:-
Fig. 1 illustrates in sectional elevation adifferential 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 sleeve in the form of
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 differ-
ential nut is externally screw threaded in the usual way to
enable it to be connected mechanically to a junction box
or the like.
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
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to facilitate its being installed in the groove. The cross-
sectional dimensions of the ring and groove are such that the
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
the groove. The ring snaps back into position after this
movement and thereby holds the cone captive relative to the
differential nut. The flange is provided with a tapered
lead-in surface ll 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.
In 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 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
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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~
It will be seen that the invention provides a simple
method and means of holding an armour spreading cone captive
which also results in simple assembly of the cable gland.
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