Operation of solenoid braking mechanism is discussed. Illustrations of construction of the brake are provided. Device is used for braking low or medium speed shaft rotations and produces approximately ten times braking torque of similar solenoid brakes

Dane, P. H.

English

NASA Technical Reports Server

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October 1972	 B72-10669 
NASA TECH BRIEF 
Marshall Space Flight 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. 
Sprag Solenoid Brake 
ETI
The sprag solenoid brake (see Figures) produces 
approximately ten times the braking torque of similarly 
sized solenoid brakes and is not limited to low or medium 
shaft rotation speeds. The locking mechanism consists of a 
double set of sprags arranged alternately so that every 
other sprag wedges between the inner shaft and the outer 
housing to prevent rotation in one direction, while the 
remaining sprags wedge in a similar manner to prevent 
rotation in the opposite direction. The control member is 
keyed to rotate with the socket member. The sprags are 
mounted in the socket member so that a spring, which 
goes through the sprags, will pull them into contact with 
the outer housing, thus preventing rotation by the 
previously described wedging action. The sprags are 
disengaged when the wedge shaped control member is 
forced between each set of sprags pushing them apart and 
away from the outer housing. 
The control member is spring loaded to push the sprags 
apart and hold them away from the outer housing when 
no power is applied to the solenoid (see Figure 1). This. 
allows the socket member and shaft to rotate freely. When 
power is applied to the solenoid, the control member is 
pulled in parallel to the shaft which allows the sprags to 
make contact with the outer housing (see Figure 2). In 
this manner, the sprags act as. brakes to halt rotation of 
the socket member and shaft.
(nnt,nl 
Figure 2. Brake in Locked Configuration 
Thus, braking occurs when power is applied to the 
solenoid and free rotation otherwise. The reverse case, 
free wheeling with the power on and braking with the 
power off, can be accomplished by changing the control 
member to push the sprags apart when power is applied. 
Notes: 
1. Information concerning this innovation may be of 
interest to manufacturer of mechanical power equip-
ment. 
Requests for further information may be directed to: 
TechnolOgy Utilization Officer 
Marshall Space Flight Center 
Code A&PS-TU 
Marshall Space Flight Center, Alabama 35812 
Reference: B72-10669 
Outer 
Housing 
Control 
so
	
Figure 1. Brake in Freewheeling Configuration
Patent status: 
Inquiries concerning rights for the commercial use of 
this invention should be addressed to: 
Patent Counsel 
Marshall Space Flight Center 
Code A&PS.PAT 
Marshall Space Flight Center, Alabama 35812 
Source: P. H. Dane

Marshall Space Flight Center
(MFS.2 1846) 
Category 06 
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.
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Sprag solenoid brake

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