Development of mechanical device to reduce possibility of damage to motor driven needle valve is discussed. Mechanical clutch is employed to allow slippage when needle valve reaches limit of travel. Operation of system for various conditions is described

Blum, D. E.

Wiltens, J. F.

English

NASA Technical Reports Server

To
Motor I 
Sten 
Sleev 
Needle 
Valve 
Set Screw 
For Motor 
Shaft 
Drill To Suit 
Motor Shaft 
Set Screw 
To Lock 
Torque Screw 
Belleville
 
Springs 
Set Screw 
or Valve 
Stem 
July 1972	 CORRECTED COPY 
AEC-NASA TECH BRIEF 
.	 Lawrence Berkeley Laboratory
B72-10345 
AEC-NASA Tech Briefs announce new technology derived from the research and development program of the U.S. AEC 
or from AEC-NASA interagency efforts. 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. 
Stem Clutch for Motor Driven Valve
The problem: 
During operation of the servo-motor driven needle 
valve, it is necessary to prevent the valve stem from being 
seized in either an open or a closed position. Such a 
seizure could damage the stem and possibly the motor 
as a result of overload. Although designs allow auto-
matic programming of the motor operation, precise 
stopping of the motor is difficult.
The solution: 
A mechanical clutch has been developed which intro-
duces friction between the motor shaft and the needle 
valve when the latter is in danger of seizure. 
How it's done: 
In the present design, as shown in the figure, the 
needle-shaped valve is advanced into or withdrawn from 
(continued overleaf) 
This document was prepared under the sponsorship of the Atomic
	 liability resulting from the use of the information contained in this 
Energy Commission and/or the National Aeronautics and Space
	 document, or warrants that the use of any information, apparatus, 
Administration. Neither the United States Government not any per-
	 method, or process disclosed in this document may not infringe pri-
son acting on behalf of the United States Government assumes an y	 varelv nwn1 riht
https://ntrs.nasa.gov/search.jsp?R=19720000344 2020-03-17T03:30:18+00:00Z
the valve seat by a rotatable threaded stem which is con-
nected to the servo-motor. The motor shaft fits inside 
a sleeve, which is connected to the valve stem. When the 
motor shaft is turning and the valve stem stops rotating 
because the valve has closed, the pin in the spacer causes 
the spacer to overcome the friction provided by the 
Belleville spring and to slip. The amount of friction is 
easily adjusted by adjustment of the screw. 
Notes: 
1. Tests show that the clutch prevents overload in a valve 
using a 300 rpm servo-motor.
2. Requests for further information may be directed to: 
Mr. Robert J. Morris 
Technical Information Division 
Lawrence Berkeley Laboratory 
University of California 
Berkeley, California 94720. 
Reference: B72-10345 
Patent status: 
No patent action is contemplated by AEC or NASA. 
Source: Dwain E. Blum and Jean F. Wiltens 
Lawrence Berkeley Laboratory
(LRL-10032)
. 
B72-10345	 Category 07


Stem clutch for motor driven valve

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