Double hook latch provides preloading and support capability up to 80,000 pounds and opens self-energizingly when restraint linkage is released. It incorporates a double hook latch held closed by a toggle linkage attached to a flexible cable rigged in tension

Barbour, R. T.

Necker, D. E.

English

NASA Technical Reports Server

April 1968	 -	 Brief 68-10117 
NASA TECH BRIEF 
- T--'-
 ;--. 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Toggle Operated Double Latch 
Flexible Cable Support Element (Structure A( (Shown In Tension; 
That Is.	 Bellcranks	 (1) 
& (2( Are As Shown. In  
Their Closed	 Position.)
A 
Direction Of (1) Stop For End Of Spring 
Force (Tension(
Spring 
Bellcrank (3) 
Bellcrank (3)s 
Pivot Point Safety Pin Hole I (For Lockup( 
St op Link 
Pivot Point1 /	 I	 \	 B
r
jHook  
C 1	 t'-	 Bolt Link 
	
Nut _[Jjj	 Mating Element (Structure B( 
A double hook latch has been designed to provide 
preloading capability, support capability up to 
80,000 Ibs, and to be self-energizing open when re-
straint linkage is released. The design incorporates a 
double hook latch held closed by a toggle linkage 
attached to a flexible cable rigged in tension: The 
cable is routed to a centrally-located, explosive- 
actuated guillotine-type cutter. Self-energizing open 
of the double jaw hooks is by means of the spring 
force in the linkage. A bolt link and nut assembly
is used to attach the mating element (structure B) in a 
preloaded condition. 
The bolt link and nut are torqued to produce the 
required preload between the two structural elements 
(A and B) to maintain structural rigidity and assure 
opening of the hooks under adverse loading condi-
tions. Positive force is maintained by the flexible 
cable which is intercepted by the explosive-actuated, 
guillotine-type cutter (not shown). Severing of the 
flexible cable enables the spring load and preload 
(continued overleaf) 
This document was prepared under the sponsorship of the National	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States 	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States 	 will be free from privately owned rights. 
https://ntrs.nasa.gov/search.jsp?R=19680000117 2020-03-12T05:24:59+00:00Z
forces to rotate the double hook latch, thus releasing 
the bolt link assembly. 
Notes: 
1. Points A and B indicate a small offset from the 
overcenter to open position of bellcrank and inter-
connecting linkage. Point C indicates the area in 
which the attaching bolt-type link imposes an 
opening force on the double hook latch. 
2. This latch has been successfully used in aerial 
drop testing of hardware from aircraft.
Inquiries concerning this innovation may be di-
rected to:
Technology Utilization Officer 
Manned Spacecraft Center 
Houston, Texas 77058 
Reference: B68-101 17 
Patent status: 
No patent action is contemplated by NASA. 
Source: D. E. Necker and R. T. Barbour 
of North American Aviation, Inc. 
under contract to 
Manned Spacecraft Center 
(MSC-1 1377) 
Brief 68-10117	 Category 05


Toggle operated double latch

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