The present invention relates to an improved system of set screw,
compression connectors and couplings therefore for securing and/or
connecting raceways or conduits carrying electrical cable to or from
electrical boxes or enclosures. More particularly this invention pertains to
set screw and compression connectors and/or couplings fabricated from
galvanized metal tubing (s), which are suited for joining two conduit
raceways carrying electrical cable.
The conventional electrical metal tubing including connectors
employed metal bodies with considerable wall thickness and of greater
length. Such connector bodies use enhanced quantity of raw materials
which rendered them bulky and unwieldy. Consumption of enhanced
quantity of raw materials added to the cost of production, pushing up the
price of the finished product.
The principal object of the present invention resides in arriving at
products which have not only reduced size but also have reduced wall
thickness.
A further object of this invention is to provide metal tubings and
glands for leading electrical wires and cables therethrough, said metal parts
being lightweight, reduced in size and user-friendly.
A still further object of this invention is to provide electrical
metal tubings (hereinafter referred to as 'EMT') which are easy to handle,
offer better grip to the workmen, thereby enhancing work efficiency.
Another object to this invention is to provide an EMT which use
less raw material in making the products, are lightweight and thus
extremely cost effective.
The foregoing objects are achieved in accordance with the present
invention which relates to an improved system of set screw, compression
connectors and couplings therefor, for securing and/or connecting raceways
or conduits carrying electrical cable to or from electrical boxes or enclosures,
said system being particularly suited for joining two conduit raceways
carrying electrical cable, which comprises hollow tubular metal body
equipped with means for securely holding electrical cable running there
through, characterized in that said means comprises a lock nut for
establishing a tight grip on the cable, threaded part of the coupling at one
end of the tube for holding the said lock nut, at least one 3-way screw
provided on the body of the said metal tubing, and a compression nut at the
other end of the said metal tube filled onto fine - pitched threads for
securing the cable over which the said system is filled. The said
compression connector carries an outer compression nut, a locknut and an
inner compression ring and the compression coupling has threaded ends
fitted with compression nuts carrying compression rings in each of the said
compression nuts detachably housed inside a circular groove provided in the
interior surface of the lip of the said nuts. The metal body used as
connectors and/or couplings in accordance with this invention may have
varying degrees of wall thickness and length. The wall thickness varies
between 1.397 and 2.921 mm, and length may vary between 33.5 and
100.71 mm, respectively, depending on the mode of use.
The aforesaid locknut is preferably hexagonal or octagonal in
shape which affords a convenient mode of operation for the person handling
it.
The tubular body serving as screw connector and coupling
therefor is provided with threaded holes and recesses for holding 3- way
screws which in turn are used to hold electrical wires/cables passing
through the "throat" or inner recess of the tubular body firmly in place.
Compression fittings, as in the case of screw fittings, are cither
connectors or couplings meant for joining conduit raceways to an enclosure
or switch box (in case of a connector), and/or for joining two conduit
raceways in case of a coupling. Compression fittings form a tight seal by
applying a compressive force to the pipes and pipe fittings. The said fittings
get compressed against the pipe on application of pressure with a force
sufficient to eliminate all blank spaces remaining in the joint.
The compression fittings mentioned above has an outer
"compression Nut" and an "inner ring," called a "compression ring". When
the nut is tightened, it clamps down on the compression ring causing it to
conform to the circumference of the pipe. Proper orientation of the
compression ring is an important requirement to achieve the desired
objective.
The "compression connector" mentioned above is a metal tubular
body hollow inside, both ends of which are threaded. The upper part of the
connector carries a locknut and lower part of the threaded portion has a
"lip" or a circular extended part serving as the limit upto which the nut can
travel. The lower threaded part of the connector carries a "compression nut",
the lower inside surface of which is threaded to be screwed onto the lower
threadings of the compression connector. The lip of the said compression
nut bulges outwardly, thereby forming a circular groove inside which houses
a compression ring. As pointed out above when the nut is tightened, it
clamps down on the said compression ring whereby it tends to conform to
the circumference of the pipe and/or cable joints.
The compression coupling is a hollow cylindrical metal body with
threadings at both ends and divided or separated into segments by means of
a circular notch or recess. Compression nuts with inside threadings and
compression rings are fitted at both ends of the said coupling, which provide
effective hold on pipes or glands carrying electrical cables/wires. The
internal diameter of the compression coupling varies from 15mm to 32mm,
depending on mode of use and/or customer requirement.
The compression ring referred to above is a steel strip, usually
made from high carbon steel, the width of which is optimally 6-13 mm and
the length may be made to vary, depending on the circumference of the
groove or housing provided either in a compression nut or/and in a
compression coupling. The length of the steel strip varying between, say, 66
and 360 mm, is imparted a shape of an open-ended ring one end of which is
shaped as a "step", the other end is formed as an inverted step, so that on
application of pressure the ends make a match and form into a ring, leaving
hardly any gap or space between the ends."
The invention will now be more particularly described with the
help of the illustrative drawings accompanying the provisional specification
wherein -
Fig. 1 shows the front view of the screw connector
Fig. 2 is the sectional view of the connector of Fig. 1
Fig. 3 shows the front view of the coupling and
Fig. 4 shows the sectional view of the coupling showing the
locations of the 3-way screw.
Fig. 5 gives the front view of the compression connector
Fig. 6 stands for front sectional view of the compression
connector
Fig. 7 shows the front view of the compression coupling and
Fig. 8 is the front sectional view of the compression coupling.
With regard to Fig. 1, (1) is the body of the hollow connector, (2)
shows the polygonal locknut, (3) is the threaded part of the coupling. (4) is
the 3-way screw. The locknut (2) may be hexagonal or octagonal in shape,
preferably with notched parts/portions serving as finger rest for affording
better grip.
As regards Fig.2, (5) shows the 'throat', e.g. the inner surface of the
threaded portion of the tubular hollow metal connector, (6) is the elevated
band provided at the end of the threaded part of the connector body, aimed
at arresting the movement of the locknut (2).
Referring to Fig.3 representing a sectional view of the connector (4)
shows the location of 3-way screw on each segment (7) of the tubular metal
connector separated by a notch or recess (8) which marks the boundary
between the segments.
Turning next to Fig. 4, showing the front view of the connector
which has (4), (7) and (8) as important parts thereof, having the same
significance as in Fig.3.
With regard to Fig. 5 showing the front view of the compression
connector, in which (2) and (6) have the same significance as given in Fig. 2,
(9) shows the threaded parts and (10) stands for compression nut carrying
inside a compression ring (not shown), located in the groove or housing
provided therefor.
In Fig. 6 depicting front sectional view of the compression
connector, numerals (2), (6), (9) and (10) have the same significance as given
above.
Fig. 7 is for the front view and Fig. 8 stands for the front sectional
view of the compression coupling, and numerals (8) and (10) used therein
have the same significance as given in connection with Fig. 5 hereinabove.
The articles of this invention are usually made from galvanized
steel pipes, the inside diameter of which varies between 18 mm and 30.33
mm at the unthreaded end. As to the "throat", the inside diameter, varies
between 14.22 and 26.64 mm. The overall length of the connector may be
made to vary between 33.50 mm and 100.71 mm, respectively.
With regard the coupling shown in Figs. 3 and 4 of the drawings,
the effective length varies between 39.88 mm and 52 mm, 'throat' varies as
in Figs. 1 and 2 and the wall thickness is optimally 1.39 - 1.4 mm. The
external diameter of the coupling varies between 18 and 33.33 mm.
It is to be kept in mind that all gauging is to be done only after
plating.
As mentioned above, the present invention offers a number of
advantages, e.g.
(i) the products being lightweight are easy to handle.
(ii) the connector has a polygonal locknut affording better
grip.
(iii) handling of the materials is rendered easy, particularly on
high locations, due to their lightweight construction and
(iv) the products are both cost effective and user friendly.
(v) the construction of the newly designed fittings has been
completely redesigned through detailed Value Analysis &
Value Engineering (VA/VE) to use steel inmost optimized
manner, which will ensure following end usage benefits
for the users :
Optimized body construction will enable users the
case of handling, especially for bigger sizes
- Significant reduction in fatigue for assembling fittings
particularly on high locations due to their lightweight
construction
Fittings will consume considerably less space during
assy ensuring better space utilization
- Higher number of parts can be handled at a height
ensuring better assy time management
- Much Higher quantity of fittings can be transported
under same weight category, ensuring reduced per
unit material transportation cost
(vi) L/D Ratio of the body construction of the connectors has
been redesigned and optimized to ensure following
benefits:
- Will ensure 100% UL conformance for all product
validation requirements
- Better rigidity of the construction will enable the
fittings to withstand higher bending load in assembled
conditions
Higher usage longevity of the fittings will ensure
reduced overall long time maintenance cost
(vii) Gland Ring construction has been redesigned to ensure
optimized closing & better grip with the conduits for
having 100% UL product conformance
(viii) All TR Series Compression fittings now incorporates fine
threaded compression nuts to ensure perfect torque &
better grip with the conduits
(ix) New designed UNF - 2A 2 drive screws have been
introduced in the Set Screw Fittings to ensure perfect
torque & better grip with the conduits
As the invention may be embodied in several forms without
departing from the spirit or essential characteristics thereof, it should be
understood that the above described features are not limited by any of the
details of the foregoing description, unless otherwise specified, but rather
should be construed broadly within its spirit and scope and, therefor, all
changes, alternatives and modifications that fall within the meets and
bounds of the foregoing description or equivalences of such meets and
bounds are intended to be embraced by the aforesaid description .
"Having described the invention in detail with particular reference
to the illustrative drawings accompanying this specification, it will now be
more specifically defined by means of claims appended hereafter".
We claim :
1. An improved system of set screw, compression connectors and
couplings therefor, for securing and/or connecting raceways or conduits
carrying electrical cable to or from electrical boxes or enclosures, said
system being particularly suited for joining two conduit raceways carrying
electrical cable, which comprises hollow tubular metal body (1), equipped
with means for securely holding electrical cable running there through,
charactcri2cd in that said means comprises a lock nut (2) for establishing a
tight grip on the cable, threaded part of the coupling at one end of the tube
(1) for holding the said lock nut, at least one 3-way screw (4) provided on the
body of the said metal tubing, and a compression nut (10) at the other end
of the said metal tube filled onto fine pitched threads (9) for securing the
cable over which the said system is fitted.
2. A system as claimed in Claim 1, wherein the tubular body (1) serving
as Screw Connector and coupling therefore is provided with threaded
recesses for holding a plurality of # 2 head tri - combo or 3- way screws (4)
which enable the electrical wires / cables passing through the "throat" or
inner recess of the said tubular body firmly in place.
3. A system as claimed in Claims 1 and 2, wherein the hollow metal
tubular body (1) has one end threaded carrying a locknut (2) on the
threaded portion (3) to afford a better grip on the said tubular body, and the
other end serving as the compression connector carries an outer
compression nut (10) around fine pitch threads (9), which in turn is
equipped with compression rings on each of the said compression nuts,
preferably machined and detachably housed inside a circular groove
provided in the interior surface of the lip of the said nuts.
4. A system as claimed in Claims 1 and 3, wherein the said lock nuts are
either hexagonal or octagonal in shape affording a convenient grip for the
person operating it.
5. A system as claimed in Cluims 1 to 4, wherein the inner surface of the
external threaded portion of the tubular metal connector known as "throat"
(5) serves as the inlet for the electrical cable/wires and the exterior threaded
portion terminates on a band (6), aimed at arresting the downward
movement of the locknut (2).
6. A system as claimed in Claims 1 to 5, wherein the said connector is
divided into two segments (7) separated by a notch or circular recess and
each such segment carries a threaded recess or groove for holding a "tri-
combo" screw (4).
7. A system as claimed in Claims 1 to 6, wherein the lower threaded
portion of the connector carries a compression nut (10), the lip whereof
bulges outwardly, thereby forming a circular groove inside which houses a
compression ring and when the said nut is tightened, it clamps down on the
compression ring compelling it to conform to the circumference of the pipe
and/or cable joints.
8. A system as claimed in Claim 7, wherein the said compression ring is
formed from a high carbon steel strip, width of which is optimally 6-13 mm
and length varying between 66 and 360 mm, and imparted a shape of open-
ended ring, one end of which is shaped as a 'step' and the other end is
formed as an inverted step, so that on application of pressure the ends make
a match and form into a ring.
9. A system as claimed in any of the preceding Claims, wherein the
preferred dimensions of the tubular body are as follows :
i) inside diameter of the tube - from 18 mm to 30.33 mm ;
ii) inside diameter at the "Throat" - from 14.22 mm to 26.64 mm ;
iii) overall length of the connector - from 33.50 mm to 100.71 mm ;
iv) effective length of the coupling - from 39.88 mm to 52 mm ;
v) wall thickness - from 1.397 mm to 2.921 mm
and
vi) external diameter of the coup- - from 18.00 to 33.33 mm ;
ling
10. An improved system of set screw, compression connectors and
couplings therefor for securing and connecting raceways or conduits
carrying electrical cable to or from electrical boxes or enclosures.
Substantially as hereinbefore described with particular reference to the
drawings accompanying the provisional specification.

The present invention pertains to an improved system of set
screw, compression connectors and couplings therefore suited for
joining two conduit raceways carrying electrical cable, comprising a
hollow tubular metal body (1) with means for securely holding
electrical cable running therethrough characterized in that said means
comprises a lock nut (2) for establishing a tight grip on the cable,
threaded part of the coupling at one end of the tube (1) for holding the
said lock nut, at least one 3-way screw (4) provided on the body of the
said metal tubing, and a compression nut (10) at the other end of the
said metal tube filled onto fine - pitched threads (9) for securing the
cable over which the said system is fitted.