S€Pt° 8, 1959
G. c. slTz
2,903,670
PLUG TERMINAL l
Filed March 24, 1954
a4
’
INVENTÓR.
Gilbert C. Sì’cz
United States arent O rfice
2,9()131576l
Patented Sept. 8, 1959
2
Other important features and objects of the invention
.tto which reference has not been made hereinabove will
‘appear hereinafter when the following description and
claims are considered with the accompanying drawings.
2,903,670
PLUG TERMINAL
Gilbert C. Sitz, Paxtonia, Pa., assignor to
Incorporated
Application March 24, 1954, Serial No. 413,413
6 Claims. (Cl. 339-128)
In this speciñcation and the accompanying drawings I
have shownk and described a preferred embodiment of my
invention, but it is to be understood that such embodi
ment is not intended to be exhaustive nor limiting of the
invention but, on the contrary, is given for purposes of
10 illustration in order that others skilled in the art may
fully understand the invention and the principles there
of and the manner of applying it in practical use so that
they may modify and adapt it in various forms, each as
may be best suited to the conditions of a particular
This invention relates in general to plug contact as 15
semblies and more particularly to plug conductor termi
use.
Figure l is a fragmentary view in cross section of a
nals of the snap-in lock type.
In the conventional type of snap-in lock plug termi
nals, a metallic pin contact element, usually formed by
typical form of plug receptacle for the purpose of illus
`trating the manner in which the plug terminal may be
mounted therein;
machining or casting is secured to the end of a lead 20
Figure 2 is a fragmentary plan view of the plug re
conductor and inserted and retained in a plug receiving
cep-tacle; and
receptacle by means of a wire spring detent and co
operating recess arrangement. Commonly, the recess
takes the form of an annular groove on the pin element
Figure 3 is a view in cross section of the plug
terminal.
In order to illustrate the objectives of the present in
with «the detent being a wire spring mounted in the side 25 vention it will be described in connection with one par
walls of the receptacle, although the reverse arrange
ticular form the cooperating plug »and receptacle may
ment wherein the spring detent consists of a wire insert
take. It is to be understood, however, that the inven
within the contact pin is also utilized. In either case the
tion may be adapted to other forms of plugs and re
inclusion of a Wire spring in the plug contact assembly
ceptacles according to the applications and purposes for
has 'several disadvantages, among these being that the 30 which the plug assembly is designed. Referring to Fig
wire detent is particularly subject to distortion through
ure l, generally designated at `ll is a plug receptacle in
accidental mishandling or abuse, yor through acquisition
which a plug terminal, generally `designated at 3, is in
of a permanent set due -to continued use. Obviously, set
ser-ted and thereby to be retained in electrical contact
ting of the spring from its original character would im
with a cooperating contact element, not shown, that may
pair or perhaps destroy its effectiveness to hold the plug 35 be »an integral part of receptacle l or external thereto,
terminal in place.
the form of such contact element being immaterial.
Plug terminals in the conventional form are generally
While the contact portion of plug terminal 3 may take
restricted to metallic construction which obviously re
any convenient form, for purposes of illustration, how
quires that the plug receptacle be of electrical insulating
ever, plug 3 includes a pin contact nose 5 extending
material even though a metallic structure may be pre 40 beyond the rear side of receptacle Il whereby to engage
ferred as where strength is a design factor. In addition,
with an external contact element which may be of the
the conventional plug terminal has the further disad
form shown and described in my copending application,
vantage of not being wholly insertable in the receptacle,
S.N. 411,969, filed February 23, 1954. Receptacle 1
the exposed portion including the point at which the lead
may be of any suitable material, either electrical con
conductor is a?xed to the terminal. In order to protect
ducting or nonconduoting, and typically is provided with
the plug terminal from short-circuiting and from break 45 a plug receiving aperture 2 into which projects a keeper
`age at the point of connection, it has been the practice
or detent 4 that serves to retain plug terminal 3 in the
in many instances to provide for the assembly some form
receptacle in a manner to be described. Detent 4, in the
of covering, usually being either a separate covering ele
embodiment disclosed, is simply formed by providing a
ment placed over the assembly after connection, or a
lip on the rear face of the receptacle which extends over
molded insulation surrounding the exposed portion of 50 a small segment of aperture 2 as shown in Figure 2.
the plug terminal, which ‘adds to the diñiculty and ex
In the preferred embodiment of the invention plug 3
pense of manufacture.
gener-ally includes a pin contact body 6 of any suitable
It is, therefore, an object of the present invention to
conducting material, which is mounted in a sleeve 8 of
provide an improved plug terminal which is effective, 55 insulating material, such as nylon or other suitable plastic
yet simple and inexpensive to produce by automatic
material having sufficient resilience and ñexibility. It
means.
is contemplated that insulating sleeve S should substan
Another object of Ithe present invention is to provide
tially enclose pin Contact body 6 whereby upon insertion
a plug terminal having an improved snap-in lock ar
into the aperture 2 the engagement areas of receptacle
rangement in which the taking of a permanent set is
1 and plug 3 will be between sleeve S and the side Walls
60
immaterial.
of aperture 2, the conductive Contact body 6 being fully
A further object of the present invention is to provide
insulated from receptacle I. Contact body 6, however,
a plug terminal in which the electrical connection be
may be of sufficient length, as at pin 5, to project from
tween the lead wire and terminal is inherently protected
the insertion end of sleeve 8 a suílicient distance to pro
by the arrangement of the plug elements.
vide an external contact surface for the plug.
65
Still another object is to provide a plug terminal
While sleeve 8 may be directly molded over contact
»adapted for use with plug receptacles of any material of
body 6, it is preferred that the elements be separately
construction.
formed to facilitate automatic manufacture, sleeve 8 be
An additional objective resides in the provision of a
ing separately molded and Contact body 6 being stamped
commercially feasible organization which will be sub
from sheet metal stock and rolled into tubular form as
stantially foolproof in use and which overcomes certain
shown in Figure 3. To maintain the elements assembled
well-known disadvantages inherent in the prior art.
a shank seciton 10 of contact body 6 is enlarged in diam-l
2,903,670
3
eter to provide a shoulder 11 which cooperates with an
annular stop shoulder l2 within sleeve 8 and serves to
limit the insertion of contact body 6 within the sleeve.
Enlarged shank section l@ is provided with a flared end
14 which, by virtue of having a larger diameter than an
internal annular bead 15 in the end of sleeve 8, snaps into
a cooperating groove lo, after distending the end of sleeve
8 at bead l5, concomitant with shoulder 1l abutting
shoulder l2. Bead l5, after contraction behind flared
end i4, serves to retain contact body 6 within sleeve 8.
A stop shoulder i7 formed by enlarging the end section
18 of sleeve 8 defines the limit of insertion of the plug
into aperture 2 by engaging the face of receptacle 1. The
plug is retained in the receptacle by means of an annular
groove 2t) in the in insertion end of the sleeve 6, groove Z0
providing a recess for seating detent 4 coincident with
shoulder 17 engaging the face of receptacle 1. lt is con
templated, of course, that detent 4 shall extend suflicient
ly far into aperture 2 so as to prevent free passage of the
plug therethrough. Hence, to permit groove 2% to be
moved into cooperative relationship with detent 4, the
forward end of sleeve 8 is relieved from contact body 6,
as by enlarging at 2l the inner diameter thereof, whereby
as the plug is inserted into the receptacle, sleeve 8 may
yield under pressure from detent 4. After detent 4 seats
in groove 20, the forward end of sleeve 8 snaps back into
its original shape thereby to maintain the plug in position.
and so avoid taking a permanent set.
Forces beyond a
certain amount, however, will bring the shaft of the nose
in the region Z7 into engagement with the nylon molding
at its left hand end, as viewed in Figure 3, at the opening
into the enlarged portion of diameter 21. This enlarged
diameter 21 serves, therefore, not only to provide the de
sired relief for detent 4 but also to inject a region of
clearance for limited yielding movement of nose 5 when
the plug is positioned in an aperture 2. The nylon skirt
at 2l backs up the shaft of the nose, however, when ex
cessive force is applied to it and provides a ñrm rein
forcement against further disalignment of the metal con
ductor within the dielectric sleeve.
Changes in construciton will occur to those skilled in
the art and various apparently different modifications and
embodiments may be made without departing from the
scope of the invention.
The matter set forth in the fore
going description and accompanying drawings is offered
by way of illustration only. The actual scope of the in
vention is intended to be defined in the following claims
when viewed in their proper perspective against the prior
art.
I claim:
l. A plug terminal for insertion in a plug receiving
receptacle having a detent projecting therein comprising
a contact member, a resilient sleeve fitted on said member,
a recess in said sleeve for cooperating with the detent to
retain said terminal in the receptacle, the forward end of
The forward edge of sleeve 8 may be inclined to form
said sleeve from said recess being spatially disposed and
a ramp or camming surface Z2 to guide more efficiently
30 longitudinally fixed relative to said member for yieldably
detent 4 to groove 20.
impeding movement of said recess into and out of coopAs best shown in Figure 3, the plug 3 constitutes the
eration with the detent for yieldably securing said terminal
terminal of an electrical lead 23 which may be secured
to contact body 6 by any suitable means. It is preferred,
however, that the diameters of the insulated portion 24
and the stripped portion 25 of lead 23 be substantially the
same as the diameters of enlarged shank 10 and nose 5,
respectively, of contact body 6 which may thus be suitably
crimped or swaged to lead 23, as by indentations 26, with
in the receptacle.
2. A plug terminal for insertion in a plug receiving
receptacle having a detent projecting therein comprising
a contact pin, a resilient sleeve fitted on said pin, the
insertion end of said sleeve being relieved from and
longitudinally ñxed relative to Said pin and having an
inclined edge, an annular groove in said end adjacent
in that poriton of plug 3 which is received in recep-tacle l.
As thus connected, when the plug is mounted in the re 40 said inclined edge for cooperating with the detent to
maintain said terminal in the receptacle, said inclined
ceptacle the points at which contact body 6 are secured
edge engaging and snapping under the detent upon the
to lead 23 are within the body of the receptacle, and hence,
seating of the detent in said groove during insertion of
are fully protected from external shock.
said terminal in the receptacle.
It will be evident that improved means are provided
3. A plug terminal `for insertion into a plug receiving
whereby the failure of a plug of the snap-in type due to 45
setting or distortion of the snap member is minimized.
Moreover, it is to be noted that even should the yieldable
forward end of sleeve S become slightly distorted, no
receptacle having a detent projecting therein comprising
to conform to the desired shape in order to reenter aper
enlarged sleeve retaining portion for snapping within said
a contact member, a resilient sleeve fitted on said mem
ber, a first portion of said sleeve having an enlarged in
ternal diameter to define inwardly opposed stop shoulders
impairment of the locking function thereof results since
the forward end of sleeve 8, including ramp 22, is forced 50 at the ends thereof, said contact member including an
sleeve and into engagement with said stop shoulders, a
ture 2 during withdrawal of the plug from the receptacle.
second portion of said sleeve being yieldably disposed
In a typical application embodying the invention the
relative to said member, a recess in said second portion
multiple receptacle will take the form of a molded panel
provided with apertures 2 and will be relatively rigid and 55 for cooperating with the detent to maintain said terminal
in the receptacle, said second portion snapping under the
unyielding. Sleeve S, of nylon or other suitable ma
detent to bring said recess into cooperation with the
terial, will be accurately molded to an external diameter
detent upon insertion of said terminal in the receptacle.
íitting within the interior surface defined by an aperture 2.
4. A plug terminal for insertion in a plug receiving
The inner surfaces within sleeve 3 will make a nice force
iit with shank section l0 of the metal plug. Thus the 60 receptacle having a detent projecting therein comprising
a tubular contact member including a pin contact portion
nose of the plug will be cushioned coaxially, with the
and an enlarged shank portion having a flared end, said
axis of aperture 2. The parts may, therefore, be mass
portions forming a stop shoulder at the junction there
produced and yet each nose, when the assembly is com
between, a resilient insulating sleeve having first and
plete, will be held by the nylon sleeve exactly where it
should be with respect to its cooperating contact spring. 65 second opposed internal annular shoulders for cooperat
ing with said stop shoulder and said flared end respec
An advantage inherent in the present assembly arises
tively to retain said sleeve on said member, the inside
from the fact that the nylon possesses some natural resil~
diameter of said sleeve at said second shoulder being
ience so that a bending force applied to the end of the
nose of the plug can move the plug slightly, within the
less than the diameter of said flared end so that upon
yieldability of the nylon, to bring the axis of the nose 70 assembly of said sleeve on said member said iirst shoulder
abuts said stop shoulder as said flared end snaps under
to a slight angle with respect to the axis of the aperture
and into engagement with said second shoulder, the for
and in this manner the nose may accommodate itself
ward end of said sleeve being yieldably dispose-d relative
to a contact spring bearing up-o-n the nose with greater
to said member, an annular groove in said forward end
than normal pressure. Similarly the nose can yield under
a blow, or through other unintended forces applied to it 75 for cooperating with the detent to maintain said terminal
2,903,670
5
in the receptacle, said forward end being arranged to
behind said ramp to define a shoulder, said forward end
snap under the detent upon the seating thereof in said
groove when said terminal is inserted in the receptacle.
5. A plug terminal for insertion in a plug receiving
being spatially disposed relative to said contact element,
receptacle having a detent projecting therein comprising
a contact member, a resilient sleeve secured on said
member, the forward end portion of said sleeve being
yieldably disposed relative to said member and con
strained to Hex primarily about axes of flexure parallel
a detent projecting from said body member and inter
secting said passageway and cooperating with said shoul
der for impeding movement of said plug thereby, the plug
periphery at the high point of said ramp closely matching
the conñguration of said passageway for A‘constraining said
resilient member to flex abofut axes of ilexure parallel to
the longitudinal aXis of said plug upon the ramp passing
to the longitudinal axis of said plug terminal, the end 10 under said detent.
of said sleeve being inclined to p-rovide an annular ramp
References Cited in the ûle of this patent
engaged by the detent upon insertion of said terminal into
the receptacle, the external diameter of said sleeve behind
UNITED STATES PATENTS
said ramp being reduced for receiving the detent upon
2,142,818
Jacobson _____________ __ Jan. 3, 1939
forcing said ramp past the detent, said sleeve having lat 15
eral means on said sleeve for stopping insertion of the
terminal within the receptacle upon movement of said
ramp past said detent.
6. In combination, a body member having a passage
way therein, a plug disposed in said passageway including 20
a contact element and a resilient member secured on
said element, the forward end of said resilient member
defining a ramp and being reduced in section immediately
2,205,146
2,330,948
2,383,909
2,469,397
2,689,337
2,694,798
2,695,394
2,711,522
2,774,810
Larkin ______________ „_ June 18,
Brand ________________ __ Oct. 5,
Buchanan ____________ __ Aug. 28,
Mezek ______________ __ May 10,
Burtt _______________ __ Sept. 14,
Cole ________________ __ Nov. 16,
Watts _______________ __ Nov. 23,
Goodwin ____________ __ June 21,
Ritter ______________ __ Dec. 18,
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