A meter for detecting tension in elastic bodies, especially in fabric straps employed as tie down straps for stowed objects is presented. The meter is characterized by a pair of elongated arms coupled together for pivotal motion about a common axis in a common plane and a strap receiver located at adjacent ends of the arms for receiving and securing adjacent portions of the strap. The receivers are supported by the arms for motion along intersecting arcs, and motion detection means is located at the opposite ends of the arms for detecting the magnitude of the motion imparted to the receivers as the strap is placed in tension

Buhler, G. V.

Havens, D. E.

English

NASA Technical Reports Server

REPLY TO
ATTN OF. GP
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
WASHINGTON, D.C. 20546
MAR i 4 1975
TO:
FROM:
KSI/Scientific & Technical Information Division
Attn: Miss Winnie M. Morgan
GP/Office of Assistant General
Counsel for Patent Matters
SUBJECT: Announcement of NASA-Owned U.S. patents in STAR
In accordance with the procedures agreed upon by Code GP
and Code KSI, the attached NASA-owned U.S. Patent is being
forwarded for abstracting and announcement in NASA STAR.
The following information is provided:
U.S. Patent No.
Government or
Corporate Employee
Supplementary Corporate
Source (if applicable)
NASA .Patent Case No.
NOTE - If this patent covers an invention made by
employee of a NASA Contractor, the following is appli
YES NO r~/
Pursuant to Section 305 (a) of the National Aeronautics and
Space Act, the name of the Administrator of NASA appears on
the first page of the patent; however, the name of the actual
inventor (author) appears at the heading of column No. 1 of
the Specification, following the words "...with respect to
an invention of ..."
' O
Bonnie L. Woerner
Enclosure
https://ntrs.nasa.gov/search.jsp?R=19750011543 2020-03-19T20:49:36+00:00Z
United States Patent
•
Fletcher et al.
[in 3,864,953
[45] Feb. 11, 1975
[54] METER FOR USE IN DETECTING TENSION
IN STRAPS HAVING PREDETERMINED
ELASTIC CHARACTERISTICS
[76] Inventors: James C. Fletcher, Administrator of
the National Aeronautics and Space
Administration with respect to an
invention by; George V. Buhler,
18570 Santa Ynez St., Fountain
Valley, Calif. 92708; Dale E.
Havens, 323 Avienda Cerritas,
Newport Beach, Calif. 92660
[22] Filed: Oct. 11,1973
[ 2 1 ] Appl. No.: 405,342
|52] U.S. Cl 73/143, 33/148 D
[51 ] Int. Cl G01I 5/06
[58] Field of Search 73/143, 95, 89, 88 R;
33/147 D, 148 R, 148 D, 148 E
[56] References Cited
UNITED STATES PATENTS
1,300,790 4/1919 Tretch 33/147 D
1,848,828 3/1932 Griffin 73/143 UX
2,376,038 5/1945 Dawson 33/147 D
2.468,496 4/1949 Ingle 33/148 R
3,492,731 2/1970 Diehl
 : 33/148 D
FOREIGN PATENTS OR APPLICATIONS
479,098 4/1936 Great Britain 73/88 R
1,101.733 4/1955 France 33/148 R
Primary Examiner—Charles A. Ruehl
Attorney, Agent, or Firm—Wayland H. Riggins; L. D.
Wofford, Jr.; John R. Manning
[57] ABSTRACT
A meter for use in detecting tension in fabric straps
having predetermined elastic characteristics. The
meter is characterized by a pair of elongated arms dis-
posed in juxtaposed, substantial parallelism, a clevis
interconnecting the arms for pivotal motion in a com-
mon plane about a common axis, a pair of juxtaposed
receivers integrally related with the first ends of the
arms and supported for arcuate motion thereby, said
receivers being configured to receive and secure
therein a pair of adjacent portions of a fabric strap,
and a pressure-responsive device mounted at the sec-
ond ends of the arms for measuring and indicating the
magnitude of arcuate motion imparted to the receivers
as tension-induced stretching of the strap occurs.
2 Claims, 5 Drawing Figures
PATENTED FEB111975 3,864,953
1
3,864,953
15
20
25
METER FOR USE IN DETECTING TENSION IN
STRAPS HAVING PREDETERMINED ELASTIC
CHARACTERISTICS
ORIGIN OF THE INNVENTION
The invention described herein was made in the per-
formance of work under a NASA contract and is sub-
ject to the provisions of Section 305 of the National
Aeronautics and Space Act of 1958, Public Law
85-568 (72 Stat. 435; 42 U.S.C. 2457). 10
BACKGROUND OF THE INVENTION
The invention relates to meters for detecting tension
in elastic bodies and more particularly to a meter for
use in indicating tension in fabric straps employed as
tie-down straps for stowed objects.
It is, of course, common practice to employ cables,
straps, lines and other similar devices for securing
stowed objects in place aboard vehicles of various
types, as well as in compartments subjected to vibra-
tory motion and the.like. Normally, such devices are
"snugged down" by an operator who through his senses
of feel is able to determine the sufficiency of the ten-
sion within the device. However, it has been found that
when stowing objects aboard spacecraft and the like, a
precise tensioning of the tie-down devices must be ef-
fected.
Normally, lightweight fabric straps are provided for
securing objects in place aboard spacecraft. For rea-
sons which are readily apparent to those engaged in
stowing objects aboard spacecraft, the straps employed
must be placed in predetermined tension. Unfor-
tuantely, tension must be measured between the strap's
buckle and a secured end thereof. In some cases, access
to the strap is quite limited. This, of course, increases
the difficulties encountered in appropriately tensioning
the strap.
Of course, tensiometers and the.like often are used
to measure the tension of steel bands, cables and the
like as they extend over relatively clear spans. Such de-
vices make use of the deflection of an eccentrically
loaded column and normally include wheatstone brid-
ges for providing data read-out indicative of the magni-
tude of tension detected. These devices tend to be com-
plicated, generally are expensive to manufacture and
often require more space than there is available for
their use in detecting tension in tie-down straps.
Therefore, devices such as tensiometers and the like
simply do not satisfactorily fulfill the need for a simple
and economic device which can readily be employed in
determining the sufficiency of the tension of a fabric
strap as the strap is tightened for securing objects in a
stowed condition aboard spacecraft.
It is therefore a general purpose of the instant inven-
tion to provide an improved meter which is particularly
suited for use in indicating tension over a small span of
a fabric strap placed in tension as the strap is tightened
for securing objects in a stowed condition aboard
spacecraft and the like.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the instant invention to provide an
improved meter for use in measuring the tension of
straps as the straps are tightened.
It is another object to provide a meter for use by per-
sonnel in stowing objects aboard spacecraft utilizing
fabric straps for tie-down purposes.
40
50
It is another object to provide a meter particularly
adapted to provide a direct and instant read-out of the
tension of a fabric strap employed for securing objects
in a stowed condition aboard spacecraft.
Another object is to provide a meter particularly
suited for use in providing intelligence indicative of
tension over a small span of a fabric strap as a tension
load is applied thereto.
These and other objects and advantages are achieved
through the use of a pair of elongated arms coupled to-
gether for pivotal motion about a common axis in a
common plane, a strap receiver located at adjacent
ends of the arms for receiving and securing therewithin
adjacent portions of the strap, said receivers being sup-
ported by the arms for motion along intersecting arcs,
and motion detection means located at the opposite
ends of the arms for detecting the magnitude of the mo-
tion imparted to the receivers as the strap is placed in
tension.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a fragmented perpsective view depicting
one manner in which the meter of the instant invention
may be employed.
FIG. 2 is a perspective view, on an enlarged scale, of
the meter illustrated in FIG. 1.
FIG. 3 is a front elevational view of the meter shown
in FIGS. 1 and 2.
FIG. 4 is a fragmented view taken generally along
line 4-4 of FIG. 3.
FIG. 5 is a sectioned end view of the meter, taken
generally along line 5—5 of FIG. 3.
DESCRIPTION OF THE PREFERRED
EMBODIMENT
Referring now to the drawings wherein like reference
characters designate like or corresponding parts
throughout the several views, there is shown in FIG. 1
a meter 10 embodying the principles of the instant in-
vention.
As shown in FIG. 1, the meter 10 is attached to a fab-
ric strap 12 employed as a tie-down device for securing
an object, such as a container 14; in a stowed condition
within a locker, generally designated 16.
It is, of course, to be understood that use of the meter
10 is not limited to use in the performance of proce-
dures for stowing objects aboard spacecraft, and that
the meter can be employed in substantially any in-
stance wherein the tension of a strap having a propen-
sity to elongate under tension is to be determined.
Therefore, it is to be understood that while the meter
10 is hereinafter described as having particular utility
in carrying out stowage procedures conducted aboard
spacecraft, the meter can be employed quite satisfacto-
rily for numerous similar purposes.
The meter 10 includes a pair of juxtaposed arms, des-
ignated'18 and 20, respectively, disposed in substantial
parallelism. The arm 18 includes a rigid link 22 orthog-
onally related to the arm 18. The link is rigidly affixed,
at its base, to the arm 18, while the distal end of the link
22 is provided with a clevis 24. The clevis 24 is pro-
vided with a clevis pin 26 concentrically related to an
axis about which the arms 18 and 20 are afforded oscil-
lation by the pin. As a practical matter, the clevis 24 is
of a yoke-like configuration while the clevis pin 26 is
seated at each of its opposite ends in suitable coaxially
related openings, not designated, formed in the clevis
3,864,953
20
25
24 and is extended through a suitable bore, also not
designated, provided in the arm 20. Thus the clevis pin
26 serves as a.bearing pin for supporting both of the
arms 18 and 20 for oscillatory displacement about a
common axis. This displacement causes the adjacent 5
ends of the arms 18 and 20 to scribe intersecting arcs
having different radii.
Provided at adjacent first ends of the arms 18 and 20
there is a pair of receivers, designated 28 and 30. It is
important here to note that the distance between the '°
pivot pin 26 and either of the receivers 28 and 30 is
substantially less than the distance between the pivot
pin 26 and the opposite ends of the arms 18 and 20. As
illustrated in FIG. 3, the distance between the receivers
and the pivot pin is a predetermined multiple of the dis- '5
tance between the pivot pin and the opposite ends of
the arms. Thus, it should readily be apparent, that the
motion imparted to the first ends of the arms 18 and 20
is magnified at the opposite ends thereof.
The receivers 28 and 30 serve to attach the meter 10
to the strap 12, as illustrated in FIG. 1. Since the receiv-
ers 28 and 30 are of a common design and configura-
tion, a detailed description of a single one of the receiv-
ers is deemed adequate to provide a complete under-
standing of the invention.
As shown in FIG. 4, the receiver 28 includes a slotted
opening 32 having planar surfaces, not designated, ar-
ranged in spaced parallelism for receiving therebe-
tween a planar portion of the strap 12. The opening 32
 30
is suitably dimensioned and configured so that the strap
may be readily inserted into and extracted from the
opening 32. In order to secure a received portion of the
strap within the slotted opening 32, there is provided a
clamp screw 34 having a knurled head, not designated, 35
and a screw-threaded body 36. The body 36 is seated
in a screw-threaded bore formed in the distal end por-
tion of the arm 18, intersecting the slotted opening 32.
The clamp screw 34 preferably is provided with a con-
centrically related needle 40. 40
The needle 40 is secured to the body 36 of the clamp
screw 34 and penetrates the fabric of the strap 12 as the
clamp screw is tightened for thus assuring that the strap
is secured to the receiver 28. Of course, where desired,
the configuration of the needle 40 may be modified or 45
even deleted and appropriate substitutions made there-
for, depending upon the particular material and the na-
ture of the strap and the purpose thereof. In any event,
it should be understood that the clamp screw 34 for the
receivers 28 and 30 serves to secure the meter 10 to ad- 50
jacent portions of the strap 12.
At the ends of the arms 18 and 20, opposite the re-
ceivers 28 and 30, respectively, there is mounted a
pressure-responsive device, generally designated 42,
through which the magnitude of the relative motion im-
parted to the receivers 28 and 30 is measured and a vi-
sual read-out is provided. The pressure-responsive de-
vice 42 includes a spring-loaded scale 44 mounted on
the arm 18 having a plunger 46 extended toward the
adjacent end of the arm 20. The adjacent end of the
arm 20, on the other hand, supports an adjustable anvil
48 disposed in coaxial alignment with the plunger 46.
The anvil 48 preferably is a screw-threaded member
having a knurled head, not designated. The anvil is sup-
 65
ported for axial adjustment while a stop nut 50 is pro-
vided for securing the anvil in an adjusted position, rel-
ative to the arm 20. Thus, the position of the anvil 48
55
relative to the arm 20 and the plunger 46 can be varied
as described.
Since pressure-responsive devices are notoriously
old, a detailed description of the device 42 is omitted
in the interest of brevity. However, it is to be under-
stood that as the receivers 28 and 30, supported by the
arms 18 and 20, are moved relative to each other, in re-
sponse to a tensioning of the strap 12, the plunger 46
and the anvil 48 are moved relative to each other. Thus
motion imparted to the arms 18 and 20, about the
clevis pin 26, as a consequence of a stretching of the
strap 12, causes the anvil 48 to act against the plunger
46 for forcing the plunger 46 to act on the scale 44. The
magnitude of the pressure applied by the anvil 48 to the
plunger 46 is indicated by the scale 44. The scale 44
provides a visual output or reading which is indicative
of the increased distance between the receivers 28 and
30. The increased distance is, of course, a function of
the tension of the strap.
Moreover, it is to be understood that other pressure-
responsive devices can be employed equally as well as
long as a visual read-out is provided for indicating
changes in the distances between the receivers 28 and
30.
OPERATION
It is believed that in view of the foregoing descrip-
tion, the. operation of the device will readily be under-
stood and it will be briefly reviewed at this point.
With the meter 10 assmebled in the manner herein-
before described, the anvil 48 is positioned relative to
the plunger 46 by threadedly advancing the anvil in a
selected direction. The stop nut 50 is then tightened for
securing the anvil 48 in place. Preferably, the position
of the anvil 48, relative to the arm 20, is such that the
plunger 46 engages the anvil 48 as parallelism is estab-
lished between the arms 18 and 20. Thus the meter 10
is prepared for operation. .
The meter is attached to a selected strap, such as the
strap 12, prior to the strap being placed in tension suffi-
cient to impart an elongation to adjacent portions
thereof. The clamp screws 34 are advanced so that the
needles 40 penetrate the fabric of the strap 12 for se-
curely fastening each of the receivers 28 and 30 to the
strap at adjacent, but spaced, locations. With the meter
10 thus secured to the strap 12, the strap is placed in
tension.
As the strap 12 is placed in tension, an elongation
thereof is effected. This elongation serves to increase
the distance between the receivers 28 and 30. As the
distances increase between the receivers, the arms 18
and 20 undergo pivotal motion about the pivot pin 26,
whereupon the anvil 48 serves to apply pressure to the
plunger 46. This pressure is transmitted to the scale 44
which provides a visual read-out indicative of the pres-
sures provided. This read-out is indicative of the rela-
tive displacement of the receivers 28 and 30 and, con-
sequently, is indicative of the magnitude of tension in
the strap. In practice, the visual read-out is compared
to an empirically established curve plotted for the ma-
terial of the strap 12 under known tension loads.
In view of the foregoing, it should readily be apparent
that the meter 10 of the instant invention provides a
practical solution to the perplexing problem of provid-
ing a simple, economic, and readily employable meter
for d'etermining tension loads of fabric straps.
3,864,953
Although the invention has been herein shown and
described in what is conceived to be the most practical
and preferred embodiment, it is recognized that depar-
tures may be made therefrom within the scope of the
invention, which is not to be limited to the illustrative 5
details disclosed.
We claim:
1. In a meter for use in indicating tension in straps
having predetermined elastic characteristics, the im-
provement comprising: 10
a pair of mutually displaceable receivers, each re-
ceiver of said pair including a block having planar
surfaces defining therewithin a slotted opening for
receiving therebetween a selected portion of a
strap having a propensity to elongate when placed 15
in tension;
means for securing said block to the strap including
a clamping pin supported for axial reciprocation
along a path intersecting the plane of said planar
surfaces; 20
a pair of elongated, juxtaposed arms, each arm of
said pair being characterized by a distal end por-
tion integrally related with one receiver of said pair
whereby each receiver is supported at one end of
said arm; 25
means including a pivot pin for pivotally coupling
one arm of said pair to the other arm thereof,
whereby the arms are supported for pivotal dis-
placement about a common axis as motion is im-
parted to the arms;
pressure measuring means mounted on one arm of
said pair, at the end opposite said distal end
thereof, and having a plunger extended toward the
other arm of said pair;
means including an anvil mounted on said other arm
of said pair in juxtaposition with said plunger for
applying thereto pressure of a magnitude dictated
by the magnitude of displacement imparted to said
receivers;
visual read-out means coupled with said pressure
measuring means for indicating the magnitude of
the pressure applied to said plunger;
the distance between said pivot pin and said plunger
being at least three times the distance between said
pivot pin and said clamping pins.
2. The meter of claim 1 wherein said coupling means
includes a rigid link projected from said one arm,
means defining within the distal end of said link a clevis
for receiving a portion of the other arm of said pair, and
a pivot pin extended through said other arm and having
its ends seated in said clevis.
30
-M
it'.
35
40
45 <
50
55
60
65


Meter for use in detecting tension in straps having predetermined elastic characteristics

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