The arresting of a moving body is improved through the use of steel cables that elongate to absorb the kinetic energy of the body. A sleeve surrounds the cables, protecting them from chafing and providing a failsafe energy absorbing system should the cables fail

Hull, R. A.

English

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States Patent [19] [111 4,304,320 
Hull 1451 Dec. 8, 1981 
r54i MOVING BODY VELOCITY ARRESTING - -  
LINE 
[75] Inventor: 
[73] Assignee: 
[21] Appl. No.: 
[22] Filed: 
Reid A. Hull, Hampton, Va. 
The United States of America as 
represented by the Administrator of 
the National Aeronautics and Space 
Administration, Washington, D.C. 
108,107 
Dec. 28, 1979 
[51] Int. Cl.3 .............................................. F16D 63/00 
[52] U.S. Cl. ...................................... 188/371; 57/906; 
244/110 C, 280/805 
[58] Field of Search ................... 188/1 C; 244/110 R, 
244/110 C, 151 R, 151 A, 151 B; 280/805; 
24/252 A; 57/202, 906 
[561 References Cited 
U.S. PATENT DOCUMENTS 
2,275,019 3/1942 Peterson ........................... 57/906 X 
2,474,124 6/1949 Schultz ............................... 188/1 C 
3,074,760 VI963 Hodgekin ........................... 188/1 C 
3,079,192 2/1963 Ottey .......................... 
3,217,838 11/1965 Peterson et al. ..................... 188/1C 
3,280,942 10/1966 Millington .......................... 188/1 C 
3,338,046 8/1967 Baur et al. ........................ 57/906 X 
3,530,959 9/1970 Kopp ........ 188/1 C 
3,862,673 1/1975 Benson ...... 188/1 C 
Primary Examiner-George E. A. Halvosa 
Attorney, Agent, or Firm-Howard J. Osborn; John R. 
Manning; Wallace J. Nelson 
[571 ABSTRACT 
The invention consists of an improvement in the art of 
arresting a moving body through the use of steel cables 
that elongate to absorb the kinetic energy of the body. 
The improvement comprises a sleeve which surrounds 
the cables, protecting them from chafing and providing 
a failsafe energy absorbing system should the cables fail. 
9 Claims, 2 Drawing Figures 
ARRESTING 4 
LOAD 4 
https://ntrs.nasa.gov/search.jsp?R=19820010727 2020-03-21T16:07:32+00:00Z
.S. Patent Dec. 8, 1981 
12 13 I 
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FIG 
IG. P 
4304,328 
1 
MOVING BODY VELOCITY ARRESTING LINE 
ORIGIN OF THE INVENTION 
The invention described herein was made by an em- 
ployee of the United States Government and manufac- 
turered and used by or for the Government for govern- 
mental purposes without the payment of any royalties 
thereon or therefore. 
TECHNICAL FIELD O F  THE INVENTION 
The invention relates to the art of arresting velocity 
of a moving body. Specifically, the invention consists of 
an improvement in the use of an annealed cable to elon- 
gate thereby absorbing the energy of the moving body. 
BACKGROUND OF THE INVENTION 
Various devices have been used to arrest the motion 
of a body. Among those devices have been nets and 
elastic cords. A difficulty with these is that the elasticity 
of the cords or net causes a significant rebound which 
can be damaging to the object. This occurs because as 
the elastic member elongates it stores large amounts of 
the energy of the moving body. After elongation, the 
member rapidly contracts releasing the stored energy 
and reimparting it to the object. To overcome this prob- 
lem metal cables have been used in place of elastic mate- 
rials. The energy of the object is absorbed by the cable 
causing the cable to elongate. Unlike an elastic cord, the 
cable is permanently deformed so there is no rebound 
shock to the object. Annealed cables have been used to 
increase the elongation potential of the cable. U.S. Pat. 
No. 3,217,838 to Peterson et a1 discloses such a cable. A 
difficulty with annealed cables is that they must be 
handled with great care. Any chafing of the cable, espe- 
cially during elongation, can cause the cable to fail 
before reaching its expected length. 
It is therefore an object of the present invention to 
increase the reliability of an annealed cable arresting 
line by protecting such a line from chafing. 
Another object of the present invention is to improve 
an arresting line by providing a failsafe protection in 
case the line fails. 
These and other objects of the present invention to- 
gether with the advantages attendant therewith will be 
readily apparent when the specification is taken in con- 
junction with the attached drawings to which it relates. 
STATEMENT OF THE INVENTION 
In accordance with the present invention, the an- 
nealed cable is routed through a tube which may be 
woven of dacron or similar filaments. This tube forms a 
sleeve which surrounds the cable. The sleeve is made 
longer than the cable so as to allow the cable to elongate 
and absorb the energy from the moving body. The 
sleeve is stitched to the cable anchors so as to afford 
failsafe protection. If the cable fails, the sleeve will 
absorb the remaining energy through its own elonga- 
tion within design limitations. 
DESCRIPTION O F  THE DRAWINGS 
FIG. 1 is a cutaway plan view showing the cable and 
FIG. 2 is a side view showing how the cable is at- 
sleeve; and 
tached to its anchors; 
25 
2 
DETAILED DESCRIPTION OF THE 
INVENTION 
The invention can be understood best by referring to 
the drawings in which any particular numeral desig- 
nates the same element throughout the figures. 
Referring now to FIG. 1, there is shown an arrester 
designated generally by the reference numeral 18. Ca- 
bles 12 and 13 extend from anchor 14 to anchor 55. 
Anchors 14 and 15 are metal shackles that are con- 
nected to the moving body and the restraining force, 
respectively. For example, the restraining force could 
be a parachute and the moving body an object dropped 
from an airplane. Cables 12 and 13 have been partially 
annealed to increase their elongation potential. Type 
302 stainless steel cable cleaned and subjected to 1650" 
F. for fifteen minutes in a vacuum furnace was found to 
elongate as much as 40 percent with only a 50 percent 
loss in strength. Cables 12 and 13 are connected to an- 
chors 14 and 15 via copper tube 16, 17, 18, and 19. Soft 
annealed copper tubing is used so that the cables do not 
chafe against the anchor which could cause failure of 
the cable. Swages 28, 21, 22 and 23 hold the cables in 
place. Swages are annealed and carefully fitted so as not 
to weaken the cable. In practice no failure of the cables 
was produced by these fittings. FIG. 2 gives a better 
view of the copper tubes and swage fittings. 
Returning now to FIG. I, sleeve 24 surrounds cables 
3o 12 and 13. sleeve 24 may be a braided material, woven 
of dacron or similar filaments. Sleeve 24 is stitched 
together at end 25 and end 26 after passing through 
loops 27 and 28 in anchors 14 and 15. It is important that 
the stitching 25 be strong enough to enable the sleeve to 
35 develop its full strength. Holes 29 and 30 allow cables 
12 and 13 to emerge from sleeve 24 before they are 
attached to anchor 15. Similar holes 31 and 32 in the 
other end of the sleeve 24 allow the cables to be at- 
tached by anchor 14. Sleeve 24 is approximately 30 
40 percent longer than cables 12 and 13 in order to allow 
the cables to elongate without the sleeve absorbing the 
energy. The sleeve is crumpled to enable it to fit be- 
tween the anchors. 
In operation, the cables 12 and 13 absorb the energy 
45 of a moving body at a nearly constant rate as they elon- 
gate, This markedly reduces the maximum arresting 
load experienced compared with that experienced in an 
elastic arresting system. Recoil of the line is also greatly 
diminished. Once the line has elongated 30 percent, 
50 absorbing most of the body's energy, sleeve 24 is pulled 
taut. The negligible amount of energy remaining in the 
body is absorbed by sleeve 24. Additionally, if one of 
the cables fails, the sleeve serves as a backup energy 
absorber elongating up to 20 percent of its length while 
55 being capable of absorbing up to 50 percent of the ki- 
netic energy from the moving body. The sleeve also 
protects the cable from chafing against adjacent objects 
during elongation. An unprotected cable would break if 
subjected to chafing during elongation. It is also impor- 
60 tant that all the components of the system be made of 
nondeteriorating and noncorrosive type materials since 
they involve safety applications and also may entail a 
relatively long shelf life. Materials such as stainless 
steel, copper and dacron meet these requirements. 
The invention can be used in connection with any 
kinetic energy absorbing system. For example, some of 
the uses to which the invention could be put include 
safety restraints on emergency vehicles, nondestructive 
65 
3 
4,304,320 
freefall testing, shroud lines on parachutes, and ground 
snatch by a fixed wing aircraft. 
It is understood that the foregoing description is a 
particular embodiment of the invention and is therefore 
merely representative. For instance, the novel sleeve 
could be placed around a plastic line instead of a steel 
cable and would still provide the failsafe energy absorb- 
ing system and protect the line. Obviously there are 
other variations and modifications of the present inven- 
tion in light of the above teachings. It is therefore un- 
derstood that within the scope of the appended claims 
the invention may be practiced otherwise than as specif- 
ically described. 
What is claimed as new and desired to be secured by 
Letters Patent of the United States is: 
1. A device for arresting the velocity of a moving 
object comprising: 
energy absorbing means for absorbing the kinetic 
energy of a moving object by elongating, said en- 
ergy absorbing means being attached at opposite 
ends to an anchor means; and 
sleeve means loosely surrounding said energy absorb- 
ing means at least in the non-elongated condition of 
said energy absorbing means for protecting said 
energy absorbing means from chafing, and for pro- 
viding a failsafe in case of failure of said energy 
absorbing means, said sleeve means being anchored 
to said anchor means at ends corresponding to ends 
5 
10 
15 
20 
25 
30 
35 
45 
50 
55 
65 
4 
of said energy absorbing means under all condi- 
tions of operation. 
2. A device as in claim 1 wherein said sleeve means is 
a braided material woven of filaments into a tube ap- 
proximately 30 percent longer than said energy absorb- 
ing means, said energy absorbing means being routed 
through said tube. 
3. A device as in claim 2 wherein said energy absorb- 
ing means comprises at least one annealed metal cable. 
4. A device as in claim 3 wherein said energy absorb- 
ing means is a pair of steel cables, said steel cables being 
looped through said anchor means; and 
tubing means surrounding the steel cables at the point 
of contact with the anchors to prevent chafing. 
5. A device as in claim 4 wherein the tubing means is 
annealed copper. 
6.  A device as in claim 4 wherein the ends of the steel 
cables are attached to the steel cables after being looped 
through the anchors by swages fitted and clamped so as 
not to weaken the cables. 
7. A device as in claim 4 wherein said sleeve means 
has ends thereof looped through said anchor means; the 
ends of said sleeve means spacing said steel cables to 
prevent chafing. 
8. A device as in claim 2 wherein said energy absorb- 
ing means comprises a plastic line. 
9. A device as in claim 2 wherein the sleeve means is 
dacron. * * * * *  


Moving body velocity arresting line

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