System measures unidirectional force without interference from other directional forces. The measuring apparatus is mounted so that it only moves vertically and is constrained from horizontal and rotational movement. This system can be used to accurately measure small forces in one direction, or as an analytic balance

Behrendt, D. R.

Hegland, D. E.

English

NASA Technical Reports Server

Analytical Balance 
Lower Taut Wire
mid 
Taut Wire Set 
Transmitting Rod 
pie (Force) 
May 1965	 Brief 65-10154 
•	 NASA TECH BRIEF 
NASA Tech Briefs are issued by the Technology Utilization Division to summarize specific 
technical innovations derived from the space program. Copies are available to the public from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia, 22151. 
System Measures Unidirectional Forces, Excludes Extraneous Forces 
The problem: In order to make precise unidirec-
tional force measurement, forces in any direction 
other than the direction of interest must be rigorously 
constrained. 
The solution: A system for measuring unidirec-
tional forces in the range 10 mg to 20 g to an accu-
racy of ±0.5 mg. The measuring member is mounted 
in such a way that it may move vertically but is con-
strained from horizontal or rotational movement.
How it's done: The system consists of a tubular 
framework that mounts detecting, measuring, and 
balancing devices, plus a taut wire suspension system 
which constrains movement of a force-transmitting 
rod to the vertical only. The rod, solenoid, and LVDT 
(Linear Varible Differential Transformer) core to-
gether weigh many times the forces to be measured. 
To offset this dead weight, a modified analytical bal-
ance is applied and the balance point adjusted until 
minimum output (null) is reached on the readout from 
(continued overleaf) 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States Govern-
ment, nor NASA, nor any person actingon behalf of NASA: A. Makes 
any warranty or representation, express or implied, with respect to the 
accuracy, completeness, or usefulness of the information contained in
this document, or that the use of any information, apparatus, method, 
or process disclosed in this document may not infringe privately-owned 
rights; or B. Assumes any liabilities with respect to the use of, or for 
damages resulting from the use of, any information, apparatus, method, 
or process disclosed in this document.
https://ntrs.nasa.gov/search.jsp?R=19650000153 2020-03-11T17:23:39+00:00Z
the LVDT. The sample (force) is then attached to the 
lower end of the rod causing torque in the taut wires 
and deflection in the LVDT readout. Direct current 
is applied to the solenoid until the LVDT readout is 
brought to the null position again. The amplitude of 
the dc current required to null the LVDT is a direct 
measurement of the force exerted by the sample. 
Vertical motion of the force transmitting rod results 
in twisting of the taut wires, which requires only small 
forces. Motions of the rod in a horizontal or rota-
tional direction are transformed into bowing of the 
wires. This requires much greater forces and the rod is 
effectively limited to vertical motion over its design 
range. 
Notes: 
1. This system can be used to accurately measure 
small forces in one direction, or as an analytic 
balance.
2. Inquiries concerning this invention may be di-
rected to: 
Technology Utilization Officer 
Lewis Research Center 
21000 Brookpark Road 
Cleveland, Ohio, 44135 
Reference: B65-10154 
Patent status: NASA encourages the immediate 
commercial use of this invention. Inquiries about ob-
taining rights for its commercial use may be made to 
NASA, Code AGP, Washington, D.C., 20546. 
Source: Donald E. Hegland and 
Donald R. Behrendt 
(Lewis- 170) 
Brief 65-10154	 Category No. 05


System measures unidirectional forces, excludes extraneous forces

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server