Safety device, consisting of three separate fluid chambers, insures that two wheels of a brake system continue to function if a failure occurs

Hobson, Z. A.

English

NASA Technical Reports Server

April 1970	 Brief 70-10207 
NASA TECH BRIEF 
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 Clearinghouse for Federal Scientific and Technical 
Information, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Division, NASA, Code UT, Washington, D.C. 20546. 
Hydraulic Brake Safety Valve 
Piston "0' Ring	 Filler Port 
Filler Port 
	
Piston	 (Normally Closed) 
Closed)	 Snap Ring\
	 In 
co 
mming Fluid	 D ischarge Port 
Pressure 
Male End	
Seal "0"	 Air Bleed	
Fe male End 
Discharge	 R ing 
Port	 Valve in Normal Position 
All Brakes Operative 
Piston Forced Outboard by Pressure 
Drop in Line or Cylinder (One or Both)
Plumbing to Rear Two 
Wheels Only (or Front 
Only)'or To One Front 
Wheel and Opposite 
Rear Wheel. 
Other End Opposite. 
\
Valve in Failure' Position

Two Brakes Operative )Front or Rear Pair) 
If one wheel cylinder of a hydraulic brake system 
fails, the entire system normally becomes inoperative. 
A concept has been developed in which a safety device, 
shown in the figure, consisting of three separate fluid 
chambers, can insure that two wheels of the system 
continue to function if such a failure occurs. In this 
conceptthe master cylinder of the brake system applies 
pressure to the center chamber of the safety valve 
forcing its pistons in an outboard direction. As a re-
sult, the fluid in the outboard chambers is forced out 
to the individual wheels, causing .a braking action. 
When the pressure in the master cylinder is reduced,
the spring tension on the brake shoes forces the fluid 
back into the safety valve, and from the safety valve 
back into the master cylinder, causing the pistons^ in 
the safety valve to resume their normal position. 
Because the brake shoes wear, the brake system 
may need adjustment, or a wheel cylinder may need re-
pairs, the fluid inhe outboard cylinder should be 
checked at regular intervals. If fluid i needed, add it 
through the two filler ports while the safety valve is 
under pressure. After brakes are bled, release fluid 
pressure and close \
 filler ports; this will restore the 
pistons to their normal positions.
(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=19700000199 2020-03-17T00:12:56+00:00Z
Notes: 
1. This concept may be of interest to the manufac-
turers of automobiles, trucks, and construction 
equipment. 
2. This development is in the conceptual stage only, 
and as of date of publication of this Tech Brief 
neither a n?odel nor prototype has been con-
structed. 
3. No additional documentation is available. Specific 
questions, however, may be directed to: 
Technology Utilization Officer 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
Reference: B70-10207
Patent status: 
No patent action is contemplated by NASA. 
Source: Zone A. Hobson of 
North American Rockwell Corp. 
under contract to 
Marshall Space Flight Center 
(M FS-16444)
. 
. 
. 
7'3-1020 i 	 Category 07


Hydraulic brake safety valve

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