Release mechanism employing simple clevis fitting in combination with two pin-pullers achieves high reliability degree through active mechanical redundancy. Mechanism releases solar arrays. It is simple and inexpensive and performs effectively. It adapts to other release-system applications with variety of pin-puller devices

Paradise, J. J.

English

NASA Technical Reports Server

May 1971	 Brief 71-10080 
NASA TECH BRIEF 
Lewis Research Center 
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 Off ice, NASA, Code KT, Washington, D.C. 20546. 
High-Reliability Release Mechanism 
A release mechanism employing a simple clevis 
fitting in combination with two pin-pullers achieves 
a high degree of reliability through active mechani-
cal redundancy. The mechanism was developed as a 
Clamp Assembly (Locked) 
Pin P*uller
Tie Rod /
 
Solar Array.	 (Released CI	 Assembly
S\,f \ 
Tie Rod 
,/'
 Mounting Bed Assembly (Released) 
Clamp Assembl y 
Swivel L..	
Puller No. 1 
Fitting Pin No. 1 
Pin No. 2
properly implemented, redundant circuitry and wiring 
will reliably ensure against a malfunction occurring 
from electrical causes. They cannot, however, pre-
vent a mechanical failure of the pin-puller device. 
Pin No. G^Pin .^ 2^^^^Te^nsion 
(A) Locked (Both Pins Extended) 
Pin NO1 3 (B) Normal Release(Both Pins Retracted) 
Pin No. 1 
inNo. 0: 
(C) Release with Retraction of Pin No. 2 Only 
Tie 'Rod 
Pin Puller No. 2 Tension 
Figure 1 
release system for two solar arrays. Since the failure 
to deploy either array would compromise the entire 
mission, reliability was of paramount importance. 
This mechanism is simple and inexpensive, and has 
performed effectively. It can be readily adapted to 
other release-system applications with a variety of 
pin-puller devices. 
Pin-puller operated release systems, whether actu-
ated pyrotechnically, pneumatically, or by solenoids, 
typically achieve reliability through the use of back-
up commands, dual squibs, or redundant wiring of 
the squib, valve, and switch components. When
^rP^in 
No.Pin No. 
(D) Release with Retraction of Pin No. 1 Only

Figure 2 
The solar array assembly for which this release 
mechanism was developed is shown in Figure 1. A 
tension element (tie rod) restrains two spring-loaded 
clamp assemblies which lock the folded solar array 
against its mounting bed. The tie rod is per-
manently attached to the right-hand clamp assembly. 
As shown in the detail view, a swivel fitting clevis 
device at the left end of the tie rod is engaged be-
hind the extended shafts of two pin-pullers, which 
are mounted in a staggered manner on either side 
of the left-hand clamp assembly. These pin-pullers 
(continued overleaf) 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19710000079 2020-03-17T02:22:27+00:00Z
operate with dual squibs, but are qualified for single-
squib operation for the cross-pin shear loads as-
sociated with this application. The turnbuckle is used 
to develop the desired preload tension. The solar 
array deployment sequence is initiated by tie-rod re-
lease. 
In the locked condition (Figure 2(A)), the swivel 
fitting distributes tie-rod tension equally to each of 
the pin-puller shafts in double shear. The swivel 
fitting automatically compensates for small angular 
misalignment between the tie rod and pin-puller 
shafts. 
In normal operation of both squibs, both pins 
are simultaneously retracted, and tie-rod release is 
effected (Figure 2(B)). Since the pin-pullers are 
qualified for single-squib operation, failure of one 
squib in either pin-puller or in both pin-pullers 
will still cause this simultaneous retraction. 
In the failure modes (Figures 2(C) and 2(D)), 
the failure of either pin to retract causes eccentric 
loading of the swivel fitting, which then simply 
rotates and rides over the extended pin, releasing 
the tie-rod and clamp assemblies.
Note: 
Requests for further information may be directed 
to:
Technology Utilization Officer 
Lewis Research Center 
21000 Brookpark Road 
Cleveland, Ohio 44135 
Reference: TSP7 1-10080 
Patent status: 
No patent action is contemplated by NASA. 
Source: John J. Paradise of

Lockheed Missiles and Space Co.

under contract to

Lewis Research Center

(LEW-1 1233)
S 
Brief 71-10080
	 Category 07


High-reliability release mechanism

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