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UDC 621.867.2
IS0
I N T E R N AT I ON A L O R G A N 1 Z AT 1 ON FOR S TA N DAR 0 1 ZATl O N
IS0 RECOMMENDATION
R 703
TROUGHABILITY OF CONVEYOR BELTS
(Characteristic and method of test)
1st EDITION
March 1968
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The copyright of IS0 Recommendations and IS0 Standards
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore only
by the national standards organization of that country, being
a member of ISO.
For each individual country the only valid standard is the national standard of that country.
Printed in Switzerland
Also issued in French and Russian. Copies to be obtained through the national standards organizations.
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BRIEF HISTORY
The IS0 Recommendation R 703, Troughability of conveyor belts (Characteristic and method
of test), was drawn up by Technical Committee ISO/TC 41, Pulleys and belts (including vee-belts), the
Secretariat of which is held by the Association Française de Normalisation (AFNOR).
Work on this question by the Technical Committee began in 1960 and led, in 1964, to the
adoption of a Draft IS0 Recommendation.
In September 1965, this Draft IS0 Recommendation (No. 860) was circulated to all the IS0
Member Bodies for enquiry. It was approved, subject to a few modifications of an editorial nature,
by the following Member Bodies :
Australia France Sweden
Switzerland
Austria Germany
Turkey
Belgium India
Brazil Italy United Kingdom
Chile Japan U.A.R.
Czechoslovakia South Africa, Yugoslavia
Denmark Rep. of
Spain
Finland
Two Member Bodies opposed the approval of the Draft :
Ireland
Netherlands
The Draft IS0 Recommendation was then submitted by correspondence to the IS0 Council
which decided, in March 1968, to accept it as an IS0 RECOMMENDATION.
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ISO/R 703-1968 (E
IS0 Recommendation R 703 March 1968
TROUGHABILITY OF CONVEYOR BELTS
(Characteristic and method of test)
FORWORD
A large number of conveyor belts work in the form of a trough. If a belt is too stiff in the transverse
direction, when empty it does not rest on the central idler roller. Its balance is then unstable and it is
subject to lateral travel which may eventually cause its destruction.
It is possible to make a section of the belt take on the shape of a trough under its own weight, by
suspending the section by its edges. This indicates what happens in use when the belt is empty.
1. SCOPE
This IS0 Recommendation specifies the required characteristic of the troughability of conveyor
belts and the corresponding method of test.
2. REQUIRED CHARACTERISTIC
The minimum value of the ratio of the deflection Ftaken by the test piece during the test, to the flat
width L of the belt, should be equal to 0.05.
NOTE. - As an indication, in the case of a belt supported by three identical idler rollers, the required relationship
F
of inclination of the side idler rollers is given by the following Table :
between the ratio-and the angle
L
TABLE
Minimum values of
Angle of inclination
deflection F
the ratio
of the si& idler rollers
width L
25' 0.06
30" 0.07
35O
0.09
40' 0.12
0.17
45'
3. PRINCIPLE OF METHOD
A test piece consisting of a transverse full width section of belt is suspended at both ends with the
carrying face uppermost so that the upper edges of these ends are in the same horizontal plane.
The suspending forces act vertically and the deflection of the test piece under gravity is unaffected by
any other external force. The troughability is determined by measuring the maximum deflection of
the test piece under its own weight and is expressed as the ratio of the deflection to the flat length of
the test piece (i.e. the width of the belt).
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ISO/R 703 -1 968 (
4. APPARATUS
FIG. 1 - Apparatus for measuring deflection of test piece
(Details given only
...