Adjustable and releasable strain relief

The invention is a strain relief for an electrical connector which is terminated to a plurality of wires extending from the connector in a wire bundle. The strain relief comprises a housing which is mountable on the electrical connector, a barrel connected to the housing and arranged for nesting the wire bundle, a clamp which is applicable to the barrel to effect gripping of the wire bundle within the barrel, and the barrel being manipulable to release the clamp, thereby releasing the gripping of the wire bundle.

FIELD OF THE INVENTION 
The invention relates to a strain relief for an electrical connector. 
BACKGROUND OF THE INVENTION 
U.S. Pat. No. 4,125,312 discloses an electrical connector strain relief 
comprising a pair of similar half-shells which are adapted to be coupled 
together while surrounding a connector housing. Each of the half-shells 
includes a clamp portion, the pair of clamp portions being configured to 
clamp onto a cable exiting from the connector. The half-shells are molded 
from a plastic material, and at least one of the clamp portions has an 
integrally molded tongue that is insertable into a slot in the other of 
the clamp portions. The tongue has serrated edges which are configured to 
engage teeth within the slot, thereby securing the clamp portions together 
around the cable. 
A problem with this strain relief is that the clamp portion is not 
adjustable in size to accommodate different sizes of cable. Another 
problem is that the tongue cannot be readily disengaged from the slot of 
the clamp portion, thereby making it difficult to reuse the strain relief. 
There is a need for a strain relief which is adjustable in size and easily 
reusable. 
SUMMARY OF THE INVENTION 
The invention is a strain relief for an electrical connector which is 
terminated to a plurality of wires extending from the connector in a wire 
bundle. The strain relief comprises a housing which is mountable on the 
electrical connector, a barrel connected to the housing and arranged for 
nesting the wire bundle, a clamp which is applicable to the barrel to 
effect gripping of the wire bundle within the barrel, and the barrel being 
manipulable to release the clamp, thereby releasing the gripping of the 
wire bundle. 
In one embodiment, the strain relief comprises a housing which is 
configured to receive the electrical connector in an interior thereof. The 
housing includes first and second housing members which are hingedly 
connected together and movable relatively together and apart. Latch means 
are provided for securing the first and second housing members together in 
a closed position. The housing has an opening through which the wire 
bundle can extend, and a barrel connected to the housing is arranged for 
nesting the wire bundle exteriorly of the opening. The barrel includes 
first and second barrel members which are connected to respective ones of 
the first and second housing members and configured to straddle the wire 
bundle when the first and second housing housing members are in the closed 
position. A clamp is applicable to the barrel to effect gripping of the 
wire bundle within the barrel. The clamp is initially integral with the 
strain relief and is severable therefrom to permit application of the 
clamp to the barrel. The clamp is formed as a U-shaped member having a 
pair of arms that cooperate with one of the first and second barrel 
members by ratcheting engagement therewith, and this one barrel member is 
squeezable to release the ratcheting engagement. The clamp has a tongue 
which extends into the barrel for capturing the wire bundle between the 
tongue and the one barrel member.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
A strain relief according to the invention is useful with an electrical 
connector of the type having a plurality of contacts which are terminated 
to respective wires that extend from the connector in a cable or wire 
bundle. The strain relief prevents pullout of the wires from the contacts 
due to loads placed on the wire bundle, such as may be caused by pulling 
on the wire bundle in order to separate mated electrical connectors. 
With reference to FIGS. 1-4, strain relief 6 comprises a housing 10, a 
barrel 20 and a clamp 30. The housing 10 has an interior space which is 
configured to accommodate an electrical connector therein. The housing has 
an open front 16 to permit the electrical connector therein to 
interconnect with a mating electrical connector. As best seen in 
cross-sectional view in FIG. 4, the housing has an opening 17 at a rear 
thereof which provides a passageway from an interior of the housing to an 
interior of the barrel. The wire bundle from the connector can extend 
through the opening 17, and the barrel 20 is arranged for nesting the wire 
bundle which exits the housing 10 through the opening. The housing 10 has 
lugs 18 which cooperate with walls 42 to define a pair of opposed grooves 
43 that are configured to receive a flange of the electrical connector. 
When the strain relief is applied to the connector, a rearward axial load 
exerted on the wire bundle will cause the lugs 18 of the housing to engage 
a front surface of the connector flange, thereby transferring the axial 
load to the housing of the electrical connector and preventing pullout of 
the wires from the contacts in the connector. 
As shown in FIGS. 5 and 6, the strain relief 6 is preferably molded from 
plastic material as a one-piece integral unit. The housing includes 
relatively movable first and second housing members 11, 12 which are 
hingedly connected by a flexible hinge 13. The first housing member 11 has 
latch arms 14 which are receivable in slots 15 in the second housing 
member 12 for securing the housing members together in a closed position 
around the electrical connector. 
Similarly, the barrel 20 includes first and second barrel members 21, 22 
which are connected to the housing members 11, 12, respectively. The 
barrel members 21, 22 are semi-circular so that the wire bundle can be 
easily nested between the barrel members when the strain relief is closed 
on the connector. The second barrel member 22 is somewhat flexible. As 
best seen in FIG. 7, opposite sides of the barrel member 22 serve as 
locking arms 23 each having a locking tooth 24 near an end thereof. The 
locking arms 23 are flanked by a pair of walls 25 so as to define pockets 
26 outwardly of the locking teeth 24. The barrel member 21 has a hole 27 
for a purpose that will be explained hereinbelow. 
Referring back to FIGS. 2 and 3, the clamp 30 is connected to the barrel 20 
by a short tether 31 which can be easily severed by a standard cutting 
tool so that the clamp 30 can be applied to the barrel 20 to effect 
gripping of the wire bundle within the barrel. However, it should be 
readily apparent that the tether 31 could be formed long enough so that 
the clamp could be applied to the barrel without severing the tether. The 
clamp 30 is preferably a U-shaped member having a pair of arms 32 
interconnected by a base 33. Each of the arms has ratchet teeth 34. A 
tongue 35 extends from the base 33 between the arms 32. 
Application of the strain relief to an electrical connector will now be 
described. An open strain relief as shown in FIG. 5 is folded around a 
terminated connector by pivoting the housing members 11, 12 around the 
hinge 13. Flanges of the connector are received in the grooves 43 and the 
wire bundle is received between the barrel members 21, 22. The housing 
members 11, 12 are secured in a closed position by the latch arms 14, as 
shown in FIG. 1. The tether 31 is severed, and the clamp 30 is applied to 
the barrel by installing the clamp open end first over the first barrel 
member 21, as shown in FIG. 7. The arms 32 enter the pockets 26 which are 
dimensioned so that the ratchet teeth 34 are urged into engagement with 
the locking teeth 24 by the walls 25. The tongue 35 passes through the 
hole 27 in the first barrel member 21 and compresses the wire bundle 
against the inner surface of the second barrel member 22. In this way, the 
tongue 35 along with the ratchet teeth 34 on the clamp which are in 
engagement with the locking teeth 24 on the second barrel member 22 
provide a cooperable means for adjusting an interior dimension of the 
barrel 30 to effect gripping of different wire bundles having a range of 
sizes. 
The walls 25 may be formed with converging surfaces so that the arms 32 are 
urged more closely together as the arms enter deeper into the pockets 26, 
thereby urging the ratchet teeth 34 more firmly into engagement with the 
locking teeth 24 so that the clamp 30 is held ever more tightly as the 
wire bundle is compressed. 
The clamp can be released from the barrel by squeezing together the locking 
arms 23 of the barrel member 22 with a tool such as needle nose pliers, 
thereby disengaging the locking teeth 24 from the ratchet teeth 34 so that 
the clamp can be withdrawn. The locking arms 23 can be provided with 
surfaces 28 which are arranged to be squeezed to facilitate release of the 
clamp. By previously severing the tether 31 so that a remnant 39 is left 
attached to the clamp, a convenient grip tab is provided to facilitate 
withdrawal of the clamp. 
The invention provides a strain relief that is adjustable to accommodate 
connectors having a wire bundle in a range of sizes. The strain relief has 
a clamp that is easily released to permit removal and reuse of the strain 
relief. 
The invention having been disclosed, a number of variations will now become 
apparent to those skilled in the art. Whereas the invention is intended to 
encompass the foregoing preferred embodiments as well as a reasonable 
range of equivalents, reference should be made to the appended claims 
rather than the foregoing discussion of examples, in order to assess the 
scope of the invention in which exclusive rights are claimed.