ISO 4579:2021

INTERNATIONAL ISO
STANDARD 4579
First edition
Aerospace — Drives, internal, TORX®
PARALOBE® drive — Geometrical
definition, gaging and technical
requirements
PROOF/ÉPREUVE
Reference number
ISO 4579:2021(E)
©
ISO 2021

---------------------- Page: 1 ----------------------
ISO 4579:2021(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii PROOF/ÉPREUVE © ISO 2021 – All rights reserved

---------------------- Page: 2 ----------------------
ISO 4579:2021(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Basic fastener recess configuration . 2
4.1 General . 2
4.2 Recess dimensions — metric and inch. 2
4.3 Recess drive designation . 3
5 Recess inspection . 3
5.1 Gaging equipment . 3
5.2 Gaging procedure . 4
5.3 Penetration type gage dimensions — metric and inch . 5
6 Fastener recess torque test . 5
6.1 Fixture . 5
6.2 Torque wrench/torsion machine . 5
6.3 Driver bit . 6
6.4 Test specimen . 6
6.5 Fastener recess torque test procedure . 6
6.6 Fastener recess torque values . 6
© ISO 2021 – All rights reserved PROOF/ÉPREUVE iii

---------------------- Page: 3 ----------------------
ISO 4579:2021(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO 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, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles,
Subcommittee SC 4, Aerospace fastener systems.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv PROOF/ÉPREUVE © ISO 2021 – All rights reserved

---------------------- Page: 4 ----------------------
ISO 4579:2021(E)

Introduction
The International Organization for Standardization (ISO) draws attention to the fact that it is claimed
that compliance with this document may involve the use of a patent.
ISO takes no position concerning the evidence, validity and scope of this patent right.
The holder of this patent right has assured ISO that he/she is willing to negotiate licences under
reasonable and non-discriminatory terms and conditions with applicants throughout the world. In
this respect, the statement of the holder of this patent right is registered with ISO. Information may be
obtained from the patent database available at www .iso .org/ patents.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights other than those in the patent database. ISO shall not be held responsible for identifying
any or all such patent rights.
© ISO 2021 – All rights reserved PROOF/ÉPREUVE v

---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 4579:2021(E)
Aerospace — Drives, internal, TORX® PARALOBE® drive —
Geometrical definition, gaging and technical requirements
1 Scope
®
This document specifies basic dimensions, characteristics and engineering requirements for TORX
®1)
PARALOBE recesses in aerospace fasteners.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
® ®
ISO 4580, Aerospace — Drive, internal, TORX PARALOBE , driver bit — Geometrical definition, gaging
and technical requirements
NASM1312-25, Fastener Test Methods – Method 25 – Driving Recess Torque Quality Conformance Test
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Onl
...