Rachet device transfers loads imposed on latch to support structure before latch springs resist loads, positively locks two pivoted structures on contact, and carries loads in all directions

Ulrich, G. W.

English

NASA Technical Reports Server

To Pivot
Ball 
***^ — N
Hook 
Cocking 
Ramp
Ratc 
\Conical 
Detent 
VIEW A
Spring
VIEW B VIEW C 
tching 
mp 
August 1972	 B72-10457 
S NASA TECH BRIEF
AL	 A Marshall Space Flight Center
	 4r 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Latch Mechanism 
Path of 
Point A
Point A 
Latch Locking Sequence 
The problem: 
Design a latch mechanism, without an auxiliary power 
source, that will positively lock two pivoted structures 
upon contact. 
The solution: 
Use rachet device that transfers loads imposed on the 
latch to the support structure before the loads have to be 
resisted by the latch springs.
when misaligned, and has zero slack in low load levels. 
The latch system is passive in that it uses no external 
power, and it is not precocked. The loads resisted by the 
latch are required to go through a rigid structure or 
through a friction interface before the preloaded spring 
force resists it. 
As the structures approach each other (View A), the 
cocking ramp pivots the hook about point A, cocking the 
latch. In this position the hook is cocked and preloaded 
to force the hook into the latched position. As the two 
structures close together (View B) contact is made at the 
ball and conical detent forcing the structures towards an 
aligned position. As this is taking place, the hook is closed 
while contacting the latching ramp. During this time the 
ratchet teeth are engaging to prevent back-up beyond a 
ratchet tooth. The spring load on the hook, and the 
latching ramp acts as a wedge forcing the structures 
together (View Q. 
How it's done: 
Most latch mechanisms have a small amount of slack, 
or play, that is usually removed after locking through use 
of an auxiliary power source, or the latch is precocked to 
a preloaded position. This particular latch mechanism 
positively locks the two structures on contact and is 
•.
 irreversable prior to completion of latching. The device 
is capable of carrying loads in all directions, will latch
(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=19720000456 2020-03-17T03:39:19+00:00Z
Notes:	 Patent status: 
I. Information concerning this innovation may be of	 Inquiries about obtaining patent rights to this invention sk 
interest to the automotive industry and hardware 	 may be made to: 
companies.	 Patent Counsel 
2. No additional documentation is available. Specific 	 Marshall Space Flight Center 
questions, however, may be directed to:	 Code A&TS.PAT 
Technology Utilization Officer 	 Huntsville, Alabama 35812 
Marshall Space Flight Center 
Code A&TS-TU 
Huntsville, Alabama 35812	 Source: G. W. Ulrich of 
Reference: B72-10457	
McDonnell-Douglas Corporation 
under contract to 
Marshall Space Flight Center 
(M FS-21606)
.S 
Category 08 
B72-10457


Latch mechanism

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