A quick-release electrical connector having a coupling member captive on and rotatable about a body of the connector, the member including circumferentially-spaced, forwardly-projecting tangs of polymeric material constituting a gapped barrel and having an internal screwthread thereon for engagement with an external screwthread of a mating connector. The tangs are resilient and allow rapid disconnection of the connectors upon application of an axial force sufficient to cause interaction of the internal and external screwthreads and expansion of the barrel to allow the internal screwthreads to ride over the external screwthreads. An inhibitor device is provided to selectively inhibit expansion of the barrel and separation of the connectors.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to the field of electrical connectors, and 
more particularly to the field of quick-release electrical connectors. 
2. Description of the Prior Art 
Quick-release electrical connectors are employed, for example, to make 
electrical connections between missile launch equipment and a ballastic 
missile up until launching. For such purposes, it is important that the 
connector should possess "fail-safe" characteristics. Bayonet-coupled 
connectors have been found to be unsuitable in that their quick-release 
mechanism will usually only function properly if the two parts of the 
connector have been fully coupled together. On the other hand, 
screw-coupled connectors are not prone to this failing, and furthermore, 
they have the advantage that it is easier to apply a high mating force to 
couple the two parts fully together. 
Examples of screw-coupled quick-release electrical connectors are to be 
found in U.S. Pat. No. 3,452,316. This specification describes connectors 
which have on one part a rotatable coupling ring with tangs which 
normally, in their relaxed state, diverge from one another. A retaining 
sleeve is provided in conjunction with the tangs to deflect them radially 
inwards to a position where they extend generally parallel to the axis of 
the connector. The tangs are internally screwthreaded and, when deflected 
radially inwards by the sleeve, can engage with a complementary external 
screw-thread on the other part of the connector to enable coupling of the 
two parts. A lanyard release ring or similar means is provided to enable 
the sleeve to be withdrawn from its tang-deflecting position. When the 
sleeve is thereby withdrawn the tangs spring radially outwards and are no 
longer held in engagement with the said external screwthread. Rapid 
uncoupling of the two parts by application of an axial quick-release force 
can then take place. 
With the quick-release connectors of this earlier U.S. Patent, the tangs of 
the coupling ring assume whenever possible a position in which they no 
longer secure the two parts of the connector together. The retaining 
sleeve is essential for deflecting the tangs radially inwards to a 
position where they can engage the external screwthread of the other part 
of the connector. Thus, unintentional withdrawal of the sleeve, or any 
other functional failure thereof, inevitably leads to disengagement of the 
tangs whereby premature uncoupling of the connector can occur. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide an electrical 
connector in which unintentional uncoupling of the connector is avoided, 
even if the sleeve is unintentionally withdrawn. 
In accordance with the present invention there is provided a quick-release 
electrical connector having a coupling member which is captive on, and 
rotatable about the axis of, the body of the connector and has 
circumferentially-spaced, forwardly-projecting tangs of resilient 
polymeric material constituting a gapped barrel on which an internal 
gapped screwthread is formed for engagement with an external screwthread 
on a complementary mating connector and permitting rapid separation of the 
two parts by application of an axial quick-release force sufficient to 
cause such interaction of the internal and external screwthreads that the 
barrel expands by enforced radial outward deflection of the resilient 
tangs and the internal screwthread rides axially over the external 
screwthread to effect the separation of the two connectors, and an 
inhibitor ring axially movable between a first position in which it 
inhibits the said expansion and a second position in which it permits the 
said expansion. 
Thus the tangs of the coupling member employed are not biased to a 
disengaged position. They will normally remain in screw engagement with 
the external screwthread of the complementary second part of the connector 
irrespective of the position of the inhibitor ring, whereby the connector 
is at least to some extent "fail-safe". Moreover, screw coupling and 
uncoupling can take place whether or not the inhibitor means is in its 
inhibit position. The inhibitor means preferably comprise an inhibitor 
ring. 
Connectors embodying the present invention still have quick-release 
capability in that moving the inhibitor means to its second position 
permits the barrel to expand when needed and permits the internal 
screwthread of the tangs to ride axially over the external screwthread of 
the complementary connector. Since it is necessary to apply sufficient 
axial force before the threads will interact to bring about the barrel 
expansion and the riding over action, there is less risk of accidental 
uncoupling of the two connectors. An additional advantage of connectors 
embodying the present invention is that as the tangs are of polymeric 
material, any swarf-like cuttings generated from the tangs by the 
interaction of the screwthreads will not be electrically conductive. Thus 
the risk of short circuits at the instant of quick-release is reduced. 
Additionally, and also because of their polymeric nature, the tangs will 
possess lubricating properties facilitating the riding of the internal 
thread over the external thread upon application of the quick-release 
force. 
Preferred polymeric materials for the tangs include polyvinyl acetals and 
polysulphones. These two polymers offer good mechanical properties 
together with thermal stability. Ordinarily, the coupling member as a 
whole, and not just the tangs forming the gapped barrel, will be made of 
the polymeric material. The manufacture of such coupling members is 
relatively easy, particularly when compared to the steps needed to make 
coupling rings with divergent, screwthreaded, tangs for the connectors of 
the U.S. Patent referred to previously. A hollow cylinder of the selected 
polymer can be tapped for part of its length to form an internal 
screwthread therein. Longitudinal shots can then be cut in the cylinder 
from one end to leave the tangs which constitute the gapped barrel. The 
screwthread of the gapped barrel preferably has a rounded V-shaped 
profile. This or other profiles wherein the screwthread has a sloping 
flank on its trailing side facilitate the required interaction between the 
internal screwthread of the gapped barrel and the external thread of the 
complementary connector. 
The inhibitor means and coupling member will usually be housed within an 
outer grooved sleeve, and the inhibitor ring will usually inhibit the 
expansion of the barrel by engagement with an outer gapped circular rib 
provided on the barrel. Preferably the inhibitor means is biased to its 
inhibiting position, for example by a wave spring housed behind the 
inhibitor means. It is then preferred to provide means for withdrawing the 
inhibitor means against the action of the bias. Such means may be a 
lanyard release ring to which is connected lanyards extending from the 
rear of the connector.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIGS. 1 to 3, the drawings show a two-part quick-release 
electrical connector assembly 10. The first connector 11 comprises a shell 
12 housing a block 13 of insulator material which supports a plurality of 
socket contacts 14 (only one is shown in FIG. 1). Each socket contact 14 
is secured at the end of a respective wire 15 led in through the rear of 
the block 13. In a similar manner, the second connector 16 comprises a 
shell 17 housing a block 18 of insulating material through which 
respective wires are led to plug contacts 20. 
A coupling member 21 is captive on, and rotatable about the axis of, the 
first connector 11 and has circumferentially spaced, forwardly projecting 
tangs 22 of resilient polymeric material. As can be seen in FIG. 3, these 
tangs 22 constitute a gapped barrel 23. The barrel 23 has an internal 
gapped screwthread 24 for engagement with an external screwthread 25 on 
the second part 16. Both the internal screwthread 24 and the external 
screwthread 25 are of rounded V-shaped profile. A grooved sleeve 26 
housing the coupling member 21 is secured to the rear of the gapped barrel 
23 and has a plurality of spaced longitudinal grooves 27 (FIG. 4) to 
facilitate a manual grip. 
Housed within the sleeve 26 is an inhibitor ring 28. This ring is urged 
forwardly by a wave spring 29 to adopt a position in which it is in 
encircling engagement with a gapped rib 30 on the forward end of the 
barrel 23. In this position, shown in FIG. 1, the inhibitor ring 28 
inhibits radial outward deflection of the tangs 21. A lanyard release ring 
31 is also housed within the sleeve 26 and has two diametrically opposite 
projections 32 which extend out rearwardly from the part 11. The inhibitor 
ring 28 is secured to move with the lanyard release ring 31 by screws 33 
which pass through the gaps of the gapped barrel 23, and lanyards 34 are 
riveted to the projections 32. 
In use, the first connector 11 is first coupled to the second connector 16 
by screwing the coupling member 21 of the first connector on to the 
external screwthread 25 of the second connector by gripping and rotating 
the sleeve 26 which houses the coupling member. The connector 10 is then 
in the position shown in FIG. 1. Merely pulling on the wires 15 which lead 
into the first part 11 does not result in release of the two parts of the 
connector assembly, and the two connectors 11 and 16 can be uncoupled by 
unscrewing the member with the aid of the sleeve 26. However, by pulling 
on the lanyards 34 the inhibitor ring 28 is moved to its second position 
shown in FIG. 2 where the tangs 22 are no longer constrained against 
outward radial deflection. 
With the inhibitor ring 28 in its second position, rapid separation of the 
two connectors is permitted by application of an axial quick-release force 
sufficient to cause such interaction of the said internal and external 
screwthreads 24, 25 that the barrel 23 expands by enforced radial outward 
deflection of the resilient tangs 21 and the internal screwthread 24 rides 
axially over the external screwthread 25 to effect the separation of the 
two connectors 11, 16. 
Further according to the invention there is provided a two-part, 
screw-coupled, electrical connector assembly, wherein a normally 
inoperative ratchet is provided between one of the two parts and on 
rotatable coupling member on the other of the two parts to become 
operative only when the connectors approach a fully mated condition by 
rotation of the coupling members and thereby provides a lock against 
contra-rotation of the coupling members and an audible indication that the 
fully mated condition is being approached and wherein means are provided 
permitting the lock provided by the ratchet to be overridden for 
disengagement of the two parts of the connector. 
Referring now to FIG. 4 this shows such an arrangement as a modification of 
the connectors of FIGS. 1 to 3 in which the forward end of the sleeve 26 
is extended and provided with a sawtoothed edge 35. A flange 36 on the 
second connector 16 carries a member 37 of resilient moulded plastics 
material provided with sawteeth projecting towards and in alignment with 
the sawteeth 35. The arrangement is made such that when the connector 
approaches the fully mated condition by rotation of the sleeve 26 
inter-engagement of the sawteeth prevents contra-rotation of the sleeve 26 
and hence prevents release of the connector by, for example, vibration 
which could otherwise cause releasing rotation of the sleeve 26. Moreover, 
at the same time, the clicking action of the inter-engaging sawteeth 
produces an audible noise indicative of the fact that the fully mated 
condition is being approached. 
It will be appreciated that the arrangement of the teeth 35 and the teeth 
on the member 37 constitutes a normally inoperative ratchet. It is not 
until the two connectors approach the fully mated condition that the 
ratchet becomes operative to prevent contra-rotation of the coupling ring 
or sleeve 26. At the same time audible clicking occurs by the interaction 
of the teeth. 
For disengagement of the two connectors, the locking action provided by the 
ratchet is overridden by the application of a quick-release force on the 
lanyard 34 whereby disengagement takes place as previously described with 
reference to FIGS. 1, 2, 3. 
From the foregoing, it can be readily realized that this invention can 
assume various embodiments. Thus, it is to be understood that the 
invention is not limited to the specific embodiments described herein, but 
is to be limited only by the appended claims.