Locking disk (flange) is stepped and lug is added to each arm of star wheel. These changes allow much longer cutout in star wheel stations, essentially eliminating chatter and wear. Jamming problem can be solved by extending star wheel arms and flaring slots

Debenham, C. H.

English

NASA Technical Reports Server

Improved Geneva Mechanism 
Drive Motor 
S
May 1974	 B74-10030 
NASA TECH BRIEF 
Langley 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 Office, NASA, Code KT, Washington, D.C. 20546. 
Improved Geneva Mechanism 
The geneva mechanism has been used for many years 
as a means of providing intermittent motion. The 
mechanism is normally locked during dwell times by a 
disk or flange on the input driver. However, any 
residual torque on the star wheel, just before unlocking 
or just after locking, can produce chatter, galling, 
excessive wear, or even a complete jam of the mecha-
nism. A partial solution to these problems in the past 
has been to cut out a small portion at the center of 
each station, as indicated in the illustration. This 
minimized the problems, but a more complete solution 
is obtained with a new technique.
For improved geneva mechanism operation, the 
locking disk (flange) is stepped and a lug is added to 
each arm of the star wheel, as shown in the illustration. 
These changes allow a much longer cutout in the star 
wheel stations, essentially eliminating chatter and wear. 
The jamming problem can be solved by extending the 
star wheel arms and flaring the slots. However, this 
cannot be done on a six-or-more-station mechanism 
with the driver on a through shaft because the ex-
tensions would hit the shaft. 
New, Larger Cutout 
.
Added Lugs 
('- Maximum Normal Cutout 
Drive Wheel
"	 Carrousel Shaft 
[Alternately Raised and 
Lowered 0.06 in. (1.52 mm) by 
Stepped Locking	 Vertical Actuator] 
(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=19740000030 2020-03-17T14:01:21+00:00Z
Note: 
No further documentation is available. Specific ques-
tions, however, may be directed to: 
Technology Utilization Officer 
Langley Research Center 
Mail Stop 139-A 
Hampton, Virginia 23665 
Reference: B74-10030
Patent status: 
Inquiries concerning rights for the commercial use 
of this invention should be addressed to: 
Patent Counsel 
Langley Research Center 
Code 456 
Hampton, Virginia 23665 
Source: Colin H. Debenham of 
TRW, Inc.

under contract to

Langley Research Center 
(LAR-1 1443)
. 
B74-10030	 Category 07,06


Improved geneva mechanism

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