Conduit connectors

In a conduit connector, the tubular body has on one end spaced sections of an outer flange, and the applied cap has a peripheral wall over the one body end and an inner endshoulder opposite the flange sections on the body, while the locking gland is with its flat ring base interposed between the flange sections and the endshoulder on the body and cap, respectively, and is clamped thereto on twisting the cap into a tightened condition on the connector, with the cap being also provided on its peripheral wall with a few spaced and preferably impressed round beads which in a loose condition of the cap align with the spaces between the flange sections on the body, but on a twist of the cap into its tightened condition are moved beneath the flange sections to thereby clamp the same and the ring base of the gland thereon to the endshoulder of the cap with a crushing vice-like grip.

This invention relates to conduits for electric wiring in general, and to 
connectors for such conduits in particular. 
The type of connector with which the present invention is concerned has a 
tubular body with an apertured cap which is screwed on the body, and a 
locking gland having a flat ring base and short inward prongs on and 
inclined to the base, with the body and cap having opposite inner 
shoulders and the gland being interposed with its ring base between these 
shoulders and thereby held for projection with its prongs into engagement 
with a conduit to which the connector is applied by simple and easy 
slip-on. Once a connector is thus applied to a conduit, the cap is 
tightened on the body to thereby lock the conduit to the connector through 
intermediation of the locking gland. 
While connectors of this type are satisfactory in most respects, they do 
fall short of meeting the important requirement of affording a conduit 
lock which is secure without fail in each and every connector application. 
Thus, by tightening the cap on an applied connector on a conduit, the 
gland is with its ring base clamped to the shoulders in the connector and 
is thereby also forced with its short prongs into a very tight jam fit 
with the conduit, with this jam fit between the conduit and the clamped 
gland in the connector holding the conduit which fail against accidental 
retraction from the connector, but the friction lock of the conduit to the 
connector at the clamped connection between the locking gland and the 
shoulders in the connector being more often than not too weak to hold the 
conduit against accidental turning or twisting in the connector, yet such 
a conduit hold against turning is as indispensible to a lasting and secure 
conduit connection as is a secure lock of the conduit against retraction 
from the connector. In this connection, the lock of a conduit against 
turning is no stronger than the weaker one of the locks of the gland to 
the conduit and to the connector, respectively, and this weaker lock is 
the friction lock between the gland and connector, and the deficiency of 
this friction lock in unfailingly securing a conduit against turning in 
each and every connector application is due to the fact that the 
screw-type connection of the cap with the body of the connector, coupled 
with the usually small clamping areas of the ring base of the gland and of 
the shoulders in the connector, are hardly conducive to lend to this 
friction lock adequate tightness for the purpose on tightening the cap 
with even a maximum force that can reasonably be expected from workmen on 
the job and which in any event must be below a prohibitive force at which 
the screw thread on the connector may well be stripped. 
It is an important object of the present invention to provide a connector 
of this type which, in contrast to prior connectors of this type, fully 
meets the important requirement of affording a conduit lock which is 
secure without fail in each and every connector application on applying 
the connector to a conduit with no more than a reasonable force and in a 
manner which is unmistakable and admits of no error. 
It is another object of the present invention to provide a connector of 
this type which affords the aforementioned secure conduit lock in each and 
every connector application, by arranging for the locking gland of the 
assembled connector, besides the secure and characteristic jam fit of its 
prongs with a conduit, a lock of its ring base to the connector with a 
crushing vice-like grip which is incomparably tighter than the 
aforementioned inferior friction grip between the same parts in prior 
connectors of this type, and is entirely adequate to withstand most any 
twisting force on the conduit. To this end, the lock of the gland to the 
connector is by way of compression between engaged parts of the connector 
body, cap and locking gland, of which the compression is applied to these 
engaged parts not only at preferably several spaced locations thereof, but 
their compressed areas at each of these locations are advantageously held 
to spot dimensions, and the compression between them is achieved by 
wedging the parts at their engaged spot locations to each other with a 
reasonable force but at a wedge angle which is infinitely small. With this 
arrangement, the applied compressive force, by being divided and 
concentrated on a few area spots on the engaged parts, tortures the 
affected metal of these parts far more than if this compressive force were 
undivided and applied evenly to the total continuous contact area of these 
parts, and this compressive force, produced by forced wedge action at an 
infinitely small wedge angle on the spot locations on the engaged parts, 
is of particularly high magnitude which tortures the affected metal of the 
parts into distortion that has a positive and strong interlock effect on 
the parts. 
It is a further object of the present invention to provide a connector of 
this type of which the ring base of the locking gland is in the assembled 
connector interposed between a few, preferably three or more, spaced 
sections of an outward flange on one end of the connector body and an 
inner endshoulder on the applied connector cap, and the ring base is 
clamped to these flange sections on the body and to the shoulder in the 
cap by spaced inner cam stubs on the peripheral wall of the cap on 
tightening the latter on the body, with these cam stubs being in loose 
condition of the cap aligned with the spaces between, and hence held out 
of reaction of, the flange sections on the body, but being on a twist of 
the cap into a tightened condition, shifted beneath and into camming 
engagement with the flange sections to clamp the latter and the gland base 
thereon to the shoulder in the cap and thereby also tighten the cap on the 
connector, and the cam stubs being designed to act like a wedge of an 
infinitely small wedge angle in locking the flange sections and gland base 
to the cap with the aforementioned crushing vice-like grip on tightening 
the cap with no more than a reasonable force. 
Another object of the present invention is to provide a connector of this 
type of which the aforementioned inner cam stubs on the connector cap are 
in the exceedingly simple form of round bead formations which are obtained 
by simple die impression in the peripheral cap wall. With this 
arrangement, there is eliminated the heretofore imperative and costly 
machined thread on the cap and also on the body of the connector for 
locking the gland to the connector and also tightening the cap, and these 
connector parts may, instead, be formed entirely in low-cost die 
operations. Even more important, making corrective changes in the dies, in 
the course of making the dies, for best functional results of the parts 
formed by them, as easily gauged from repeat trial operations of the dies, 
is particularly advantageous in that the die configurations, including 
those for impressing the round bead formations in the peripheral cap wall, 
will be of optimum accuracy for forming these connector parts to meet 
their various requirements and particularly the most exacting connector 
requirement of locking the gland to the connector with a crushing 
vice-like grip by wedge action of an infinitely small wedge angle. 
Further, with the dies so made to form high-precision connector parts that 
meet the various, including most exacting, connector requirements, these 
dies secure the important advantage of producing large quantities of the 
same high-precision connector parts at the exceedingly low cost which 
efficient die operations entail. 
A further object of the present invention is to provide a connector of this 
type in which the engaged body, gland and cap parts of the connector are 
securely locked to each other on twisting the cap into a tightened 
condition on the connector as aforementioned, and this tightened cap 
condition is umistakably indicated by a snap action which the one twisting 
the cap clearly feels and which occurs only when in the course of the 
twisting the cap the same reaches its tightened condition. To this end, 
the cap and body parts of the connector are provided with interference 
projections in the preferred form of simple bead-like impressions which in 
their snapped-over condition also lock the cap against accidental twisting 
into loose condition on the connector.

Referring to the drawings, and more particularly to FIGS. 1 to 6 thereof, 
the reference numeral 20 designates a conduit connector having a body 22 
with an axis x, a cap 24 and a locking gland 26. The body 22 is tubular 
and has a peripheral wall 28 and an outwardly extending endflange 30 with 
several, in this instance three, angularly spaced notches 32 which 
interrupt the flange 30 (FIGS. 4 to 6, 9 and 10). The cap 24 is of general 
cup shape, having a bottom 34 with a central aperture 36, and a peripheral 
rim 38. The locking gland 26, which is preferably of slightly resilient 
steel, is in the form of a flat ring base 40 and several spaced prongs 42 
which extend inwardly from and at an inclination to the base 40. 
In the assembled connector, the locking gland 26 is interposed between the 
body 22 and cap 24 and normally rests with its ring base 40 on the body 
flange 30, and the cap 24 is projected with its rim 38 over the body 
flange 30 and gland 26 thereon, and is with its bottom 34 aligned with the 
ring base 40 of the gland. 
The exemplary connector 20 is adapted for mounting on a box 46 or the like, 
and the connector body 22 is to this end provided with a threaded shank 48 
(FIG. 5). A conduit c is applied to the connector by simple and ready 
insertion of the conduit through the cap end of the connector, with the 
applied conduit preferably resting on a stop shoulder 50 in the body 22. 
The inserted conduit is locked to the connector, and more particularly to 
the connector body 12 through intermediation of the locking gland 26, with 
the gland 26 being to this end locked with its prongs 42 to the conduit c 
and with its ring base 40 to the body 22. The gland 26 is with its prongs 
42 locked to the conduit c on locking the ring base 40 of the gland to the 
connector body 22 by a cam action of the cap 24. To this end, the cap 24 
is provided on the inside of its rim 38 with preferably several, in this 
instance three, angularly spaced cam formations 54 which in a certain 
angular release position of the cap are in axial alignment with the 
notches 32 in the body flange 30 (FIGS. 4, 5A and 9), and which on a twist 
of the cap from its release position pass into axial alignment with the 
body flange 30 in which the latter and the gland base 40 thereon extend 
into the gaps g between the cam formations 54 in the cap and the bottom 34 
of the latter (FIGS. 5, 9 and 10), with these gaps g being so highly 
constricted widthwise that the body flange 30 and gland base 40 are within 
the confines of these gaps clamped to each other and to the cam formations 
and cap bottom with a vice-like grip of crushing proportions. 
The cam formations 54 in the cap 24 are in the preferred form of beads 
which are conveniently impressed in the rim 38 of the cap, and these beads 
are for all practical intents and purposes round or dome-shaped, although 
they are in this instance only partly round because they are continuous 
and merge with longitudinal rib formations 60 which are also impressed in 
the rim 38 of the cap and serve for a purpose described hereinafter. These 
bead-type cam formations 54 are shaped, at and in the immediate vicinity 
of their high-points p nearest the cap bottom 34, like wedges of 
infinitely small wedge angles which are highly advantageous in that they 
will coact with the trailing ends 58 of the body flange 30 at its 
interruptions in forcing the body flange and gland base thereon into the 
confines of the highly constricted gaps g between the cam formations and 
cap bottom on twisting the cap from its release position (FIGS. 4, 5A and 
9) into an exemplary lock position (FIGS. 6 and 10) with a fairly 
reasonable force which may conveniently be applied to the cap by way of 
ordinary pliers. The exemplary bead-type cam formations 54 are further 
characteristic in that their operative engagement with the body flange 30 
is confined not only to a few spaced locations thereon, but also to areas 
thereof which are of no more than spot dimensions. With the compressive 
force applied by the cam formations 54 to the flange 30 and base 40 of the 
body and gland parts being thus divided and concentrated on a few area 
spots of these parts, the affected metal of these parts is tortured far 
more than if this compressive force were undivided and applied evenly to 
the total confronting areas of these parts, and this compressive force, 
produced by forced wedge action of an infinitely small wedge angle on spot 
locations on these parts, is of particularly high magnitude which tortures 
the affected metal of the parts into distortion that has a positive and 
strong interlock effect on the parts. 
While the cap 24 is in its release position in which its cam formations 54 
are in axial alignment with the notches 32 in the body flange 30 (FIGS. 4, 
5A and 9), the cap has freedom of axial movement with its cam formations 
into and from register with the notches 32, as a result of which the 
locking gland 26 is with its ring base 40 separated from or seated only 
loosely on the body flange 30 so that the prongs 42 of the gland will 
readily yield to the conduit c on its insertion into the connector. 
However, on twisting the cap 24 from its release position and thereby 
locking the body flange 30 and gland 26 to the connector cap 24 as 
explained, the locking gland will be put under stress, with ensuing 
distortion of the prongs 42 thereof into an exceedingly tight jam fit with 
the conduit c which will certainly lock the latter to the gland 26, and 
thereby also to the body 22, against retraction from the connector. The 
jam fit of the prongs 42 of the locking gland 26 with the conduit is also 
more than adequate to resist any accidental turning of the conduit in the 
locking gland and, hence, also in the connector due to the explained 
exceedingly strong lock of the gland to the connector body. 
Provisions are also made on the connector whereby the inserted conduit c 
becomes locked to the connector on twisting the cap 24 from its release 
position (FIGS. 4, 5A and 9) in one certain direction into a predetermined 
lock position (FIGS. 5, 6 to 8 and 10). To this end, the peripheral wall 
28 of the connector body 22 is provided with a preferred single 
interference formation 62 which is to cooperate with an interference 
formation on the rim 38 of the cap 24 in the form of one of the described 
impressed ribs 60 on the cap which is identified by the reference numeral 
60a. The interference formation 62 on the cap 24 is in the preferred form 
of a round bead which is conveniently impressed in the cap rim 38. Thus, 
in the release position of the cap 24, the interference rib 60a on the cap 
24 is in the angular position in FIGS. 3 and 5 in which the same is spaced 
a short distance from the interference bead 62 on the connector body 22 in 
a counterclockwise direction. In order to lock the conduit c to the 
connector, the cap 24 must be twisted from its release position in FIGS. 3 
and 5A, clockwise in this instance, until the interference rib 60a on the 
cap encounters and snaps over the interference bead 62 on the connector 
body, with the cap then being in its predetermined lock position (FIGS. 6 
to 8 and 10) which is unmistakably indicated to the person twisting the 
cap by a clearly felt snap-action of the interference rib 60a over the 
interference bead 62. Accordingly, the only instruction to anyone for 
securely locking a conduit to a connector is to twist the connector cap 
clockwise until the explained snap-action is felt. 
The connector body 22 is further provided on its peripheral wall 28 with a 
stop formation 64 which is in the preferred form of an impressed bead of 
greater height than the interference bead 62. The stop bead 64 is 
preferably on the same level as the interference bead 62 (FIGS. 1 and 6 to 
8), with the stop bead 64 being so spaced from the interference bead 62 
that on a twist of the cap 24 from its release position (FIG. 3 and 5A) in 
the wrong direction, i.e., counterclockwise in this instance, the 
interference rib 60a on the cap will come into engagement with the stop 
bead 64 and be thereby stopped before the cam formations 54 can exert any 
clamping force on the body flange 30 and gland base 40 thereon. 
Accordingly, a twist of the cap 24 from its release position in correct, 
clockwise, direction is imperative in order to lock the conduit c to the 
connector. 
The cap 24 and the locking gland 26 are also locked to the connector body 
22 against removal therefrom. To this end, the rim 38 of the cap is 
provided on its inside with at least one, and preferably several, stop 
formations 66 in the preferred form of impressed beads. There are in this 
instance three of these stop beads 66, i.e., as many as there are 
interrupted parts of the body flange 30, with these stop beads 66 being 
angularly spaced from the cam formations 54 in the cap so that the stop 
beads 66 are in axial alignment with the three interrupted parts of the 
body flange 30 in the only angular position of the cap, i.e., its release 
position (FIGS. 4, 5A and 9), in which the same and also the locking gland 
26 could be removed from the connector body were it not for the fact that 
the interrupted parts of the body flange 30 are then in stop relation with 
the stop beads 66 (FIGS. 5, 5A and 9). 
FIG. 11 shows a modified connector 20' which may in all respects be like 
the described connector 20 of FIG. 1, except that the modified connector 
is adapted for connecting two conduits, and to that end has duplicate caps 
24', outward flanges (not shown) at each end of the connector body 22', 
and a locking gland (not shown) for each cap 24'. The connector body 22' 
is in this instance provided in its wall 28' with a peripheral groove 70 
which is preferably impressed in the body wall 28' so as to provide 
internal stop shoulders for conduits to be connected.