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INTERNATIONAL
6789
STANDARD
Second edition
1992-l 2-o 1
Assembly tools for screws and nuts - Hand
torque tools - Requirements and test methods
pour vis et &x-ous - Oufils dynamom Hriques B
Outils de mancleuvre
commande manuelle - Exigent es et mkthodes d’essai
Reference number
IS0 6789: 1992(E)
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IS0 6789:1992(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work
of preparing International Standards is normally carried out through IS0
technical committees. Each member body interested in a subject for
which a technical committee has been established has the right to be
represented on that committee. International organizations, govern-
mental and non-governmental, in liaison with ISO, also take part in the
work. IS0 collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an Inter-
national Standard requires approval by at least 75 % of the member
bodies casting a vote.
International Standard IS0 6789 was prepared by Technical Committee
ISO/TC 29, Small tools, Sub-Committee SC 10, Spanners and wrenches.
This second edition cancels and replaces the first edition (IS0 6789:1982
and IS0 7855:1985), of which it constitutes a technical revision.
Annexes A and B form an integral part of this International Standard.
Annex C is for information only.
0 IS0 1992
All rights reserved. No part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without
permission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-121 1 Genkve 20 l Switzerl and
Printed in Switzerland
ii
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INTERNATIONAL STANDARD IS0 6789:1992(E)
Assembly tools for screws and nuts - Hand torque tools -
Requirements and test methods
- Class D: screwdriver, adjustable, graduated
1 Scope
- Class E: screwdriver, fixedly adjusted
The present International Standard specifies the re-
quirements and describes the test methods and
- Class F: screwdriver, adjustable, non-
marking of hand torque tools used for controlled
graduated
tightening of bolted connections.
It applies to torque tools according to clause 2, in
particular to indicating and setting torque wrenches
according to numbers 258 and 259 of IS0 1703. 3 Requirements
3.1 Assignment of the driving square
The size of the driving square is a function of the
maximum torque value of the respective torque tool.
The assignment is carried out according to the val-
2 Classification
ues given in table 1.
The torque tools to which this International Standard
applies are classified as follows:
Table 1
Driving square nominal
a) Type I: Indicating torque tools (see annex A)
Maximum torque value
size 1)
/
- Class A: wrench, torsion or flexion bar
N-m mm
- Class B: wrench, rigid housing, with scale or 30
613
135
10
dial or display
340 12,5
1 000
20
- Class C: wrench, rigid housing and electronic
2 700
25
measurement
1) in accordance with IS0 1174.
I
- Class D: screwdriver, with scale or dial or
display
- Class E: screwdriver, with electronic
measurement
3.2 Specified measuring range
b) Type II: Setting torque tools (see annex B)
The requirements and test methods according to
this International Standard cover a specified meas-
- Class A: wrench, adjustable, graduated
uring range from 20 % to 100 % of the maximum
torque value of the respective tool.
- Class B: wrench, fixedly adjusted
The scales of torque tools of type I shall be marked
- Class C: wrench, adjustable, non-graduated with a zero position.
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IS0 6789:1992(E)
3.52 Number of cycles
3.3 Scales
All torque tools to be tested shall be cycled at
The increment between two grad uatio n marks of a
maximum capacity (or nominal capacity for tools of
scale shall not exceed 5 % of the maxi mum value.
type II classes B and E) for 5 000 cycles, in each di-
rection of operation, at a rate between 40 and
20 cycles per minute.
3.4 Tolerances
3.4.1 Indicating torque tools (type I)
4 Accuracy testing
Permissible deviation of the torque value indicated
by the tool from the simultaneous indication of the
4.1 Test device
test device shall be
The maximum permissible deviations of the test de-
- Classes A and D: + 6 % of the test device indi-
-
vice shall be + 1 % of the indicated value.
cation
The test device shall be set to zero before starting
-
classes B, C and E: & 4 % of the test device in-
the test.
dication
4.2 Test temperature
3.4.2 Setting torque tools (type II)
The tests shall be carried out after stabilization of
Permissible
...