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Патент USA US2111243

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March 15, 1938.
Filed Feb. 17, 1957
Patented Mar.' 15, 1938
, “2,111,243
coNnm'r ycornmictrIoN
Paul 0.` Hecht, Davenport, Iowa, assignor to
Kwikon Company, Chicago, Ill., la corporation
of Illinois
Application February 11, 1937, vserial No; 126,123
2 Claims.
(ci. 285-161)
The invention relates to connecters and more prevent [dislodgment of the' conduit by an end
particularly to connecters adapted for useI with wise pull.
so-called thin walled electrical conduit or tubing. ' Further objects and advantages of the inven
'I'he use of light gauge seamless steel tubing tion will become apparent as the following de
5 as an electrical conduit„known as thin walled
scription proceeds and the features 'of novelty
conduit, has numerous advantages from the
which characterize the invention are pointed out
with particularity in the claims annexed to and
' standpoint of cost, weight, and ease of manipu
lation. Such tubing may be readily bent to con
form to the contour of even intricate building
10 structures in which it is to be located without
the necessity of providing elbow joints' and the
like such as must be used with rigid conduit. Its
use has been handicapped, however, by the lack
of suitable connecters for securing the ends of
l5 the _conduit to outlet boxes, joining together sec
tions of the conduit, and for other like purposes. ,
A number of different factors have contributed
~to complicate the problem of devisingv a suitable
connecter. In the first place, the device must
20 be extremely simple and cheap to manufacture
if the ov ~all cost of the conduit system is to be
low enou to competel with older and highly de'
-veloped forms of conduits and ñttings. Also, the
device should be of such character that an ordi
25 nary electrician can install it with the few simple
forming a part of this specification.
For a better understanding of the- invention
reference may be had to the accompanying draw-`
ing in which
Figure 1 is a perspective view of a connecter
embodying the invention.
Fig. 2 is a longitudinal sectional view of the
connecter in Fig. 1 as applied to an outlet box.
Fig. 3is an enlargeddetail View of one‘of the
set screws .included inthe connecter shownv in
Fig. 1.
' Fig. 4 is an enlarged fragmentary longitudinal
sectional view of a part of the connecter shown
in Fig. 1 and a portion of the conduit inserted
therein illustrating particularly the'. contour of
the inserted portion of conduit after the con
necter has been secured thereto. .
Referring more particularly to the drawing,
the invention has been shown for purposes of il»
tools, such as a screw driver and pliers, which lustration of its various novel features as em
usually make up his kit, and it must‘be possible . bodied in a connecter adapted to secure the end
to make the installation in cramped corners and of a portion of thin> walled metal conduit to an
crevises of buildings -that are accessible only under outlet box or the like but it will be understood by
$0 the greatest 'of diiiic'ulty.~ Finally, the very qual-' those
skilled in the art that connecters'embody
ities which make thin‘ walled .conduit desirable ing the invention may be adapted for a wide
also ~niake it verydiiiiculg.` to lapply_a connecter. , variety of other uses; In general, the connecter
Its thin light gauge metal walls preclude the use ` herein contemplated is provided with a body por
of heavy compressive forces and yet the under
tion adapted to iit about the conduit and an 35
85 writers require that a connecter for such conduit, improved arrangement for securing this body
when having a diameter of three-fourths oían - portion‘in position which serves to compress a
inch for example, withstand a straight pull of .portion of the conduit wall in a hardened mass v
9«llilroximately "100 pounds.
The» problem off Ato form a bearing shoulder cooperating with a
strength. of the joint is also made more diiiicult
40 by the racc that nice nts of the parts cannot be
had since economical manufacture of the conduit
necessitates wide tolerances in its diameter.
The general object of the present invention is
to provide a simple, economical connecter for
use with thin walled metal conduit which may be
projection on the connecter to prevent dislodg 40
ment of the conduit by an endwise pull.
The particular connecter illustrated is provided
with a _generally tubular or cylindrical body por
tion Ill having a longitudinally extending open
ing Il therein adapted to be telescoped over the
end of a section of thin walled metal electrical-
manipulated by ordinary toolsv in a limited space conduit or tubing I2 (Fig. 2). An annular shoul
and which is adapted to withstand an extremely der I3 formed within the opening Il cooperates
heavy pull tending to dislodge the same from the _ with the marginal edge of the conduit I2 to limit
its endwise movement into the connecter. vThe
A more speci?vc object of the invention- is to securing arrangement hereinafter described is
provide such a 'connecter which is -adapted to of such character thatthe opening ll may be
compress a portion of the conduit wall into a made of suñiciently large diameter as to accom
hardened mass forming a bearing shoulder'co . mo'date tubing having a comparatively wide vari
operating with a projection on the connecter to ation from a standard diameter. 'I'he manufac 55
ture of the tubing or conduit is thus simplified as
well as that of the connecter since the tolerances
for the interfltting parts are comparatively large.
`As was previously noted, the particular con
necter illustrated is adapted to be secured to’an'
outlet box or similar casing member. Eor this
purpose a threaded annular extension I4 is
formed on the outer end ofthe connecter body
and terminates in a shoulder Il. Thus, as shown
10 in Fig. 2, the threaded end or boss Il may be
inserted in a suitable openingin the wall of a
box II and the connecter clamped in position.
by a lock nut- I1 cooperating with the shoulder
II to engage the marginal ’edges of the box wall.
the requirements of simplicity and ease of manip
ulation as well as the requirements as to strength
of the Joint which it forms.
It has been found that the shape of the con
duit engaging projections is quite critical espe
cially when set screws are used. Thus, itpoint
ed set screws are substituted for those illustrated,
they will pierce the conduit wall and when a
strong pull is exerted thereon a slit will be torn
in the end portion of the conduit permitting it to
be'freed from the connecter. On the other hand,
if ordinar'yflat ends are used on the set screws,
the gripping action had on the inserted c_nd of
the conduit is insumcient to maintain it in posi
A plurality of spaced projections illustrated in
the form of blunt ends or points i8 on set screws
I9 are arranged to engage the inserted end por
tion of the conduit I2. The set screws Il are ar-ranged in alinement longitudinally of the con
20 .necter body in closely spaced relation and are '
vention has been shown and described in some
detail for purposes of illustration. there is no in
strengthening ridge or rib 2l on the tubular con
appended claims are intended to cover all modifi
cations within the spirit and scope of the inven
necter body portion Il. As best shown in Fig. 3,
threaded in suitable tappedholes' formed in a
the ends I8 of the set screws i! are tapered at
an angle A which is preferably of the order of
about 60 degrees and terminate in iiat end sur
faces 2| which are of substantially smaller cross
sectional area than that of the shanir of the
screw. For the particular connecter illustrated
30 the surfaces 2| are preferably about ¿th of an
inch in diameter. ‘These blunt ends of the set
screws il are‘hardened in order that they may
readily indent the relatively soft 'steel tubing or
Upon reference to Fig. 4, it will -be seen that
the ends I I of the set screws Il engage the con
duit I2, forming- indentations' 22 therein. The
angularly disposed lrelation of the ends of the set
tion under a heavypull.
Although a particular embodiment of the in
tention tothereby limit the invention to this par
ticular embodiment but', on the other hand, the 20
I claim as my invention:
1. A ?tting for thin- walled tubular metal con 25
duit provided with a sleeve member arranged to
receive an inserted end of the thin walled con
duit', and means for securing said- sleeve to the
inserted conduit. said means' including _a plurality
of adjacent setscrews threaded in said sleeve in 30
longitudinal alinement thereon. and adapted to
deform‘the wall of thev tubular conduit inwardly
at spaced points a sumcient distance to form a
ridge of hardened metal between the screws for
increasing resistance to separation ofthe conduit 35
from the sleeve member.
2. A iltting for thi'n walled tubular metal con
duit provided with a sleeve member arranged to
screws serves to exert a wedsing action on the
receive an inserted end of the thin walled. con
portion ofthe conduit wall located therebetween,
thus compressing the'same into-a hardened mass
duit, and means for-securing said sleeve to thel
inserted conduit, said' means including a` plurality
as indicated by the heavier crosshatching in Fig.
4 at 23. It has been found that this portion of
of adjacent set screws threaded in saidtsleeve in
longitudinal alinement thereon and provided with
the conduit is hardened almostto` the point`of ’ elongated tapered blunt points adapted to de
45 crystallimtion. ,The hardened mass or lump of . form the wall of :he tubular conduit inwardly at 45
metal thus had forms a bearing shoulder coop
spaced points a suillcient distance to wedge a
erating with the lower end II of the outermost set ridge of hardened metal between the screw points
screw `I! to prevent dislodsment lof the conduit for- increasing resistance to separation of the
I2 by an endwise pull. A very effective a'nd sim
conduit from the sleeve member.
50 ple form of connecter is thus had which meets
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