Adjustable loop clamp

An adjustable loop clamp assembly provides improved retention of electrical cables, tubes or hoses. The clamp assembly comprises a flexible strap with first and second ends. A base, having an elevated platform, a lower platform, a midsection, and two side supports, receives a second end of the strap in an aperture of the midsection. The first strap end is securably affixed to the elevated platform of the base. Support holes in the side supports receive pin portions of a locking cam, the locking cam further comprising a handle portion and a cam portion. A mount bolt is receivable in alignable apertures of the lower platform and the handle portion. The pin portions of the locking cam are pivotably engaged into the mount holes of the side supports, allowing rotation of the locking cam into a position that engages the strap with the cam portion, locking the strap against the base structure, simultaneously contacting the handle portion against the lower platform, further aligning the mount holes in the handle portion and the lower platform so that when a mount bolt is passed through those holes and secured, the locking cam is prevented from disengagement.

BACKGROUND OF THE INVENTION 
The present invention relates to aircraft engine systems and, more 
particularly, to an adjustable loop clamp for securing electrical cables, 
tubes, or hoses in a fixed position. 
Loop clamps also known as "P" clamps are used widely in gas turbine engines 
for securing cables, hoses, and tubes to other engine hardware. The 
conventional loop clamp is well suited for application with objects having 
fixed controlled diameters such as tubes. However, many electrical cables 
have irregular cross-sections, the diameters of which are not 
dimensionally controlled with tight tolerances. This results in cables 
being loosely secured with existing loop clamps, because the existing 
clamps are generally designed for hard tubes with known diameters. This 
problem also results in added expense, since a number of differently sized 
loop clamps must be available for use on the same cable bundle. 
The loop clamp device has changed very little over the years which is 
surprising, considering their widespread use and the various problems 
associated with their use, such as stated above. Most assemblers agree 
that the installation of these clamps is difficult because of their 
stiffness. The use of commercially available clamps on electrical cables 
is further complicated by the fact that cable diameter dimensions, as 
stated above, are not tightly controlled, and that the cables have "soft" 
irregular cross sections. 
Tie-wraps are familiar devices that are easily installed and offer positive 
retention, regardless of the shape of the enveloped object. Designs exist 
that have mount bolt features similar to the "P" clamp, but their use is 
restricted due to temperature limitations of the materials used in making 
these ties. Additionally, cable ties are destroyed upon disassembly. 
Similar looking ties made of metal have also been explored for use. 
Unfortunately, removal of these bands after installation is a major 
obstacle that discourages their use. 
It is therefore highly desirable and an object of the present invention to 
provide an adjustable loop clamp for use in gas turbine engines, which 
provides improved retention of electrical cables. 
Another object of the present invention is to provide such an adjustable 
loop clamp wherein electrical cables having irregular cross-sections can 
be tightly secured. 
Another object of the present invention is to provide an adjustable loop 
clamp for securing flexible cables having diameters which are not 
dimensionally controlled with tight tolerances. 
These objects and other features and advantages will become more readily 
apparent in the following description when taken in conjunction with the 
appended drawings. 
Summary of the Invention 
The present invention has been developed to fulfill the needs noted above. 
The present invention is an adjustable loop clamp particularly suited for 
use on gas turbine engines and electrical distribution systems to 
controllably secure electrical cables. The adjustable loop clamp employs a 
flexible strap that is permanently joined to a steel base, such as by use 
of a rivet. A pivoting locking cam can "pinch-lock" the strap against the 
base, forming any desired loop diameter within the limits of the strap 
length. The device employs a novel positive locking of the locking cam to 
the base by a mount bolt. 
In accordance with one aspect of the present invention, an adjustable loop 
clamp assembly provides improved retention of electrical cables. The clamp 
assembly comprises a flexible strap with first and second ends. A base, 
having an elevated platform, a lower platform, a midsection, and two side 
supports, receives a second end of the strap in an aperture of the 
midsection. The first strap end is securably affixed to the elevated 
platform of the base. Support holes in the side supports receive pin 
portions of a locking cam, the locking cam further comprising a handle 
portion and a cam portion. A mount bolt is receivable in alignable 
apertures of the lower platform and the handle portion. The pin portions 
of the locking cam are pivotably engaged into the mount holes of the side 
supports, allowing rotation of the locking cam into a position that 
engages the strap with the cam portion, locking the strap against the base 
structure, simultaneously contacting the handle portion against the lower 
platform, further aligning the mount holes in the handle portion and the 
lower platform so that when a mount bolt is passed through those holes and 
secured, the locking cam is prevented from disengagement. 
In the drawings as hereinafter described, a preferred embodiment is 
depicted; however, various other modifications and alternative 
constructions can be made thereto without departing from the true spirit 
and scope of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the drawings, in FIG. 1 there is illustrated a flexible 
loop clamp assembly 10, according to the present invention. The clamp 
assembly 10 comprises a flexible strap 12 having a first end 14 and a 
second end 16. The first end 14 of the strap 12 is securably attached to 
an elevated platform 18 of a base 20, best illustrated in FIG. 2. The base 
20 further comprises a lower platform 22, a midsection 24 associating the 
elevated and lower platforms 18 and 22, and a pair of opposing side 
supports 26 attached to the elevated platform 18. 
Continuing with FIG. 1, the clamp assembly 10 further comprises strap 
attaching means, such as a rivet 28, for securably affixing the first end 
14 of the strap 12 to the elevated platform 18 of the base 20. A slot 30, 
best illustrated in FIG. 4, located in the midsection 24 of the base 20 
receives the second end 16 of the strap 12. 
A locking cam 32 illustrated in FIG. 7, comprises a handle portion 34, as 
illustrated in FIG. 5, a cam portion 36, and pin portions 38. The pin 
portions 38 are pivotably engageable into support apertures 40 of base 20, 
allowing rotation of the locking cam 32 into a position that engages the 
strap 12 with edge 50 of cam portion 36, locking the strap 12 against the 
base 20 structure, and simultaneously contacting the handle portion 34 
against the lower platform 22. A first mount bolt aperture 42 is located 
in the lower platform 22, as illustrated in FIG. 3; and a second mount 
bolt aperture 44 is located in the handle 34, as illustrated in FIG. 6. 
When pin portions 38 of locking cam 32 are pivotably engaged into the 
support apertures 40 of side supports 26, the first and second mount bolt 
apertures 42 and 44 are aligned in each of the handle 34 and the lower 
platform 22 so that when a mount bolt (not shown) is passed through 
apertures 42 and 44 and secured, the locking cam 32 is prevented from 
disengagement. 
The clamp assembly 10 preferably employs a flexible fiberglass strap 12 
that is permanently joined to a base 20, preferably manufactured of a 
corrosion resistant steel, by a joining means such as rivet 28. The strap 
12 is captured by rivet 28 through aperture 46 and permanently affixed in 
aperture 48. The pivoting locking cam 32 can "pinch-lock" the strap 12 
against the base 20, forming any desired loop diameter within the limits 
of the strap length. The strap length itself may be any desired length. 
End 16 of strap 12 can include a metal edge to prevent fraying of the 
strap 12. The clamp assembly of the present invention provides for 
positive locking of the locking cam to the base by the mount bolt (not 
shown) received through apertures 42 and 44. 
In operation, the free end 16 of the strap 12 is passed around a cable or 
hose so that the free end 16 is positioned to enter slot 30 of base 20. 
The handle 34 is rotated about pivot point, aperture 40, to a position 
that permits the free end 16 of the strap 12 to pass between the handle 
and the elevated platform 18 of base 20, and continue through slot 30 in 
the base midsection 24. The strap 12 is pulled tightly around the hose or 
cable. The handle 34, currently in the open position as indicated by 
phantom handle 34', may now be rotated into the closed position of handle 
34, whereby the flat surface of the handle and the lower platform of the 
base are brought into contact. When this is done, edge 50 at the opposite 
end of the handle 34 is being brought into contact with the strap, 
effectively locking its position with a friction force. In this position, 
the bolt holes 42 and 44 of both the base and the handle are aligned so as 
to allow a securing bolt to be passed through. The combination of clamp 
and cable, tube or hose may now be secured with the mount bolt. 
The present invention is particularly adaptable for use on gas turbine 
engines for controllably securing electrical cables having irregular 
cross-sections, the diameters of which are not dimensionally controlled 
with tight tolerances. The present invention provides the feature of a 
positive lock of the handle, afforded by the mount bolt joining the 
locking cam to the base. A tighter clamp connection is afforded by the 
device of the present invention, as compared to existing loop clamps. It 
is an advantage of the present invention that the current need to provide 
a range of clamp sizes is eliminated. 
It is seen from the foregoing, that the objectives of the present invention 
are effectively attained, and, since certain changes may be made in the 
construction set forth, it is intended that matters of detail be taken as 
illustrative and not in a limiting sense.