ISO/TS 20825:2003

TECHNICAL ISO/TS
SPECIFICATION 20825
First edition
2003-03-15
Road vehicles — Drawbar couplings,
drawbar eyes, fifth wheel kingpins, hook
couplings and toroidal eyes — Wear
limits for in-use mechanical couplings
Véhicules routiers — Chapes d'attelage, anneaux de remorquage,
pivots d'attelage, attelages à crochet et anneaux de timon toriques —
Limites d'usure pour les dispositifs d'attelage mécaniques en service

Reference number
©
ISO 2003
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ii © ISO 2003 — All rights reserved

Contents Page
Foreword. iv
Introduction . v
1 Scope. 1
2 Normative references . 1
3 Checking worn components. 2
3.1 40 mm and 50 mm drawbar couplings. 2
3.2 40 mm and 50 mm drawbar eyes. 2
3.3 50 mm and 90 mm fifth wheel kingpins . 4
3.4 Hook couplings . 4
3.5 Toroidal eyes . 4
4 Limit dimensions for worn components. 5
4.1 40 mm drawbar couplings and eyes . 5
4.2 50 mm drawbar couplings and eyes . 6
4.3 50 mm fifth wheel kingpins . 6
4.4 90 mm fifth wheel kingpins . 7
4.5 Hook couplings and toroidal eyes . 7

Foreword
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In other circumstances, particularly when there is an urgent market requirement for such documents, a
technical committee may decide to publish other types of normative document:
 an ISO Publicly Available Specification (ISO/PAS) represents an agreement between technical experts in
an ISO working group and is accepted for publication if it is approved by more than 50 % of the members
of the parent committee casting a vote;
 an ISO Technical Specification (ISO/TS) represents an agreement between the members of a technical
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rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO/TS 20825 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 15,
Interchangeability of components of commercial vehicles and buses.
iv © ISO 2003 — All rights reserved

Introduction
This Technical Specification is intended to provide limits to the wear of standardized mechanical couplings
mounted on heavy commercial vehicles, in order to ensure their safe on-road operation.
This Technical Specification has been considered necessary because the lack of any compulsory requirement
applicable to the allowable wear of mechanical couplings has meant that the competent authorities, when
checking in-use vehicles, make reference only to the design dimensions of standardized mechanical couplings.
Nor have they been taking into consideration the wear limits indicated by each mechanical coupling
manufacturer on the instructions for use and maintenance of the coupling.
This Technical Specification is addressed to all parties involved in the safe use of heavy commercial vehicles,
i.e. the owner, any competent person who conducts the periodical maintenance and the competent authorities
conducting the periodical inspection and check of in-use vehicles.

TECHNICAL SPECIFICATION ISO/TS 20825:2003(E)

Road vehicles — Drawbar couplings, drawbar eyes, fifth wheel
kingpins, hook couplings and toroidal eyes — Wear limits for
in-use mechanical couplings
1 Scope
This Technical Specification specifies the maximum allowable wear and the limit dimensions of worn
components of in-use mechanical couplings, which, when respected, will ensure the safe operation on the
road of heavy commercial vehicles fitted with such couplings.
It is applicable to the following standardized mechanical couplings:
 40 mm and 50 mm drawbar couplings (see ISO 3584);
 40 mm and 50 mm drawbar eyes (see ISO 8755 and ISO 1102);
 50 mm and 90 mm fifth wheel kingpins (see ISO 337 and ISO 4086);
 hook couplings and toroidal eye
...