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I N T E RN AT I O N A L ORGAN 12 AT I ON FOR STAN DARD 1 ZATl O N
IS0 RECOMMENDATION
R 701
I NTERNATIONAL GEAR NOTATION
SYMBOLS FOR GEOMETRICAL DATA
1st EDITION
March 1968
COPYRIGHT RESERVED
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 701, International gear notation - Symbols for geometrical data,
was drawn up by Technical Committee ISO/TC 60, Gears, the Secretariat of which is held by the
Institut Belge de Normalisation (IBN).
Work on this question by the Technical Committee began in 1950 and led, in 1962, to the
adoption of a Draft IS0 Recommendation.
In December 1965, this Draft IS0 Recommendation (No. 889) was circulated to ail the IS0
Member Bodies for enquiry. It was approved, subject to a few modifications of an editorial nature,by
the following Member Bodies :
Argentina Israel Spain
Australia Italy Sweden
Austria
Japan Switzerland
Belgium Netherlands Turkey
Chile New Zealand United Kingdom
France Norway Yugoslavia
Germany Poland
Hungary South Africa,
India Rep. of
One Member Body opposed the approval of the Draft :
Czechoslovakia
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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ISOlR 701 -1968 IE
March 1968
IS0 Recommendation R 701
INTERNATIONAL GEAR NOTATION
SYMBOLS FOR GEOMETRICAL DATA
INTRODUCTION
This IS0 Recommendation aims to unify the symbols used in different countries for the international
notation of gears with regard to the principal geometrical data defined in IS0 Recommendation
R ., (1) International vocabulmy of gears - Part I : Geomeîrical definitions.
These symbols have been chosen after detailed comparative study, taking into account the necessity
of retaining a certain number of letters for standardization of other notations at a later date, such as
those dealing with gear accuracy.
Consequently it is important
to bring national standards into line with this IS0 Recommendation, so that in future a
(1)
real intemational language of notations wiü facilitate the exchange of documents between
one country and another;
to use for geometrical data only combinations of letters or signs appearing in the alpha-
(2)
betical Annex, in order to avoid any risk of confusion with notations to be determined
later with regard to other gear data.
This IS0 Recommendation consists essentially of two parts :
-
on the one hand, the principal symbols, composed either of a single basic letter, or of a
basic letter and suffix or sign which are generally inseparable for the given term (see
Table 1);
-
on the other hand, additional suffaes or signs which may be added if necessary to the
principal symbols, in order to imply a particular qualification of the given term (see
Table 2).
The Annex gives lists classified in alphabetical order according to the Roman and Greek alphabets, on
the one hand of the basic letter symbols, and on the other hand of the suffxes and signs which have
been used in the establishment of this IS0 Recommendation and a combination of which may possibly
be used for the notation of any other term of geometrical data not explicitly mentioned in this
IS0 Recommendation.
At present Draft IS0 Recommendation No. 888.
(1)
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ISO/R 701 -1968 (E
TABLE 1 - Rincipai symbols(’)
iymbol!
No. Terms Symbols JO. 1 Terms
-
Centre distance
1 a Pitch
2 Shaft angle z Module
3 Linear speed v Diametral pitch
4 O
Angular speed Angular pitch of crown gear
5 Number of revolutions n
Tooth thickness
U
6 Gear ratio Spacewidth
7 Transmission ratio i Tooth thickness half-angle
8
Number of teeth 2 Spacewidth half-angle
...