ISO 13044-2:2021

Road vehicles - Fully automatic coupling systems 24 V (FACS) for heavy commercial vehicle combinations - Part 2: Electrical and pneumatic interface for 50 mm fifth wheel couplings

This document specifies the mechanical, electrical/electronic and pneumatic characteristics of a fully automated fifth wheel coupling system to ensure interchangeability between a towing vehicle and a coupled semi-trailer(s) with 24 V nominal supply voltage. The two vehicles together constitute an articulated vehicle or are part of a vehicle combination. This document also supports the step-by-step introduction of fully automated fifth wheel coupling systems in the market. It specifies features necessary for mixed mode operation, i.e. the combination of a fully automated coupling system (FACS) equipped towing vehicle with a conventional semi-trailer, and vice versa, the combination of a conventional towing vehicle with a FACS-equipped semi-trailer.

Véhicules routiers — Dispositifs d'attelage entièrement automatiques (FACS) à 24 V pour ensembles routiers lourds — Partie 2: Interface électrique et pneumatique pour sellettes d'attelage de 50 mm

General Information

• Status: Published
• Publication Date: 04-Jan-2021
• ICS: 43.040.70 - Couplings
• Technical Committee: ISO/TC 22/SC 40 - Specific aspects for light and heavy commercial vehicles, busses and trailers
• Drafting Committee: ISO/TC 22/SC 40/WG 1 - Mechanical couplings
• Current Stage: 6060 - International Standard published
• Start Date: 05-Jan-2021
• Due Date: 19-Feb-2022
• Completion Date: 05-Jan-2021

Relations

• Revises: ISO 13044-2:2013 - Road vehicles - Fully automatic coupling systems 24 V (FACS) for heavy commercial vehicle combinations - Part 2: 50 mm fifth wheel couplings - Electrical and pneumatic interface
• Effective Date: 23-Apr-2020

Overview

ISO 13044-2:2021 specifies the electrical and pneumatic interface for 50 mm fifth wheel couplings used in 24 V fully automatic coupling systems (FACS) for heavy commercial vehicle combinations. The standard defines the mechanical, electrical/electronic and pneumatic characteristics of an integrated electrical/pneumatic interface (EPI) module to ensure interchangeability between a towing vehicle (tractor) and semi-trailer(s). It also supports a staged market introduction by enabling mixed mode operation-compatibility between FACS‑equipped and conventional vehicles.

Key topics and technical requirements

• Scope and objectives: Interchangeability for articulated vehicles and vehicle combinations using 24 V nominal supply voltage; support for safe, automated coupling/uncoupling.
• EPI module definition: Two complementary parts-EPI plug module (trailer/king‑pin side with male contacts) and EPI socket module (tractor/fifth‑wheel side with female contacts and alignment features).
• Mechanical and alignment requirements: Guidance on mating, guiding, alignment degrees of freedom, installation requirements and protection/encapsulation of EPI parts.
• Electrical/electronic characteristics: Contact allocation, current carrying capacity, connection resistance (voltage drop), cable length considerations and compatibility with ISO 11992 digital communications.
• Pneumatic interface: Pneumatic connection layout, valve location in socket module and leakage/pressure testing requirements.
• Mixed mode operation: Features to ensure safe operation when combining FACS and conventional units (informative Annex C).
• Tests and environmental requirements: Visual and dimensional checks, connection/disconnection durability, locking device operation, current cycling, withstand voltage, vibration, shock, drop, temperature/humidity cycling, salt spray and chemical resistance, plus pneumatic leakage tests (detailed in Clause 5).
• Normative annexes: Dimensional characteristics (Annex A) and contact allocation (Annex B).

Practical applications

• Ensures interchangeable, safe automated coupling between tractors and semi‑trailers.
• Enables fleet operators and OEMs to adopt FACS while maintaining compatibility with legacy trailers (mixed mode).
• Reduces driver exposure to hazardous coupling zones, improves ergonomics and can lower maintenance and downtime for fleets.
• Supports development and certification of EPI hardware (connectors, valves, protection covers) and software for vehicle-to-trailer communications.

Who should use this standard

• Heavy vehicle OEMs and fifth‑wheel manufacturers
• Trailer and component suppliers (EPI module, pneumatic/electrical connectors)
• Fleet operators planning FACS deployment
• Test laboratories and conformity assessment bodies
• Standards developers and regulatory authorities

Related standards

Key referenced standards include ISO 13044‑1, ISO 11992, ISO 12098, ISO 7638‑1, ISO 337, ISO 1726, ISO 3842, ISO 6150, and ISO 16750 series - all relevant for mechanical dimensions, electrical connectors, communications and environmental testing.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 13044-2
Second edition
2021-01
Road vehicles — Fully automatic
coupling systems 24 V (FACS)
for heavy commercial vehicle
combinations —
Part 2:
Electrical and pneumatic interface for
50 mm fifth wheel couplings
Véhicules routiers — Dispositifs d'attelage entièrement automatiques
(FACS) à 24 V pour ensembles routiers lourds —
Partie 2: Interface électrique et pneumatique pour sellettes d'attelage
de 50 mm
Reference number
©
ISO 2021
© 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: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Requirements . 2
4.1 General . 2
4.2 Tractor and semi-trailer . 3
4.3 Mechanical interface, Manual operation . 3
4.4 EPI module . 3
4.5 Mating of the two EPI parts. 3
4.6 Guiding and alignment . 4
4.6.1 General. 4
4.6.2 Installation requirements of EPI socket module . 5
4.6.3 Installation requirements of semi-trailer-mounted EPI module . 5
4.6.4 Perpendicular degree of freedom of contacts . 6
4.6.5 Pneumatic valves in EPI socket module . 6
4.7 Encapsulation and protection . 6
4.7.1 General. 6
4.7.2 EPI plug module protection cover actuation . 6
4.7.3 Gasket between plug and socket . 7
4.8 Automation of landing legs . 7
4.9 ISO 11992 cable length . 7
4.10 Mixed mode operation . 7
5 Tests and specific requirements . 7
5.1 General . 7
5.2 Visual examination . 8
5.3 Dimensional check . 8
5.4 Connection and disconnection . 8
5.5 Locking device operation . 9
5.5.1 Application . 9
5.5.2 Requirements . 9
5.6 Current carrying capacity . 9
5.7 Connection resistance (voltage drop), cable capacitance and pneumatics . 9
5.8 Current cycling .11
5.9 Withstand voltage .12
5.10 Influence of water .12
5.11 Protection against dust .12
5.12 Endurance .12
5.13 Vibration .12
5.14 Shock resistance .12
5.15 Drop test .13
5.16 Temperature/humidity cycling .13
5.17 Salt spray .13
5.18 Chemical resistance .13
5.19 Leakage test of pneumatic connections .13
5.20 Functional test of protection covers .13
Annex A (normative) EPI module — Dimensional characteristics .14
Annex B (normative) EPI module — Contact allocation .23
Annex C (informative) Mixed mode operation .25
Bibliography .29
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 22, Road vehicles, Subcommittee SC 40,
Specific aspects for light and heavy commercial vehicles, busses and trailers.
This second edition cancels and replaces the first edition (ISO 13044-2:2013), which has been
technically revised. The main changes compared to the previous edition are as follows:
— changes to the normative references.
A list of all the parts in the ISO 13044 series can be found on the ISO website.
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 © ISO 2021 – All rights reserved

Introduction
This document specifies the integrated electrical and pneumatic connections of an automated fifth
wheel coupling system for articulated vehicles and related components.
Fully automated coupling systems improve safety for the driver and for the vehicle combinations. They
also improve the work conditions for the driver and reduce cost for the end user.
a) Higher safety standard is achieved for example by:
— a reduction of operational accidents,
— less injured drivers because there is no need for drivers to stay in the dangerous zone between
the towing and the towed vehicle while uncoupling.
b) Higher comfort level is achieved for example by:
— elimination of necessity to access the coupling, landing gears and supply lines,
— reduction of physical demands when operating the coupling and the landing gears or when
climbing on or descending from chassis to manually connect or disconnect the supply lines.
c) Cost reduction for end user is achieved for example by:
— less repair and maintenance of cables and pipes,
— less inactive periods for the vehicle combination due to less damage and repair,
— new components create space for future extensions and potentials.
INTERNATIONAL STANDARD ISO 13044-2:2021(E)
Road vehicles — Fully automatic coupling systems 24 V
(FACS) for heavy commercial vehicle combinations —
Part 2:
Electrical and pneumatic interface for 50 mm fifth wheel
couplings
1 Scope
This document specifies the mechanical, electrical/electronic and pneumatic characteristics of a fully
automated fifth wheel coupling system to ensure interchangeability between a towing vehicle and
a coupled semi-trailer(s) with 24 V nominal supply voltage. The two vehicles together constitute an
articulated vehicle or are part of a vehicle combination.
This document also supports the step-by-step introduction of fully automated fifth wheel coupling
systems in the market. It specifies features necessary for mixed mode operation, i.e. the combination
of a fully automated coupling system (FACS) equipped towing vehicle with a conventional semi-trailer,
and vice versa, the combination of a conventional towing vehicle with a FACS-equipped semi-trailer.
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 337, Road vehicles — 50 semi-trailer fifth wheel coupling pin — Basic and mounting/interchangeability
dimensions
ISO 1726-1, Road vehicles — Mechanical coupling between tractors and semi-trailers — Part 1:
Interchangeability between tractors and semi-trailers for general cargo
ISO 1726-2, Road vehicles — Mechanical couplings between tractors and semi-trailers — Part 2:
Interchangeability between low-coupling tractors and high-volume semi-trailers
ISO 3842, Road vehicles — Fifth wheels — Interchangeability
ISO 6150:2018, Pneumatic fluid power — Cylindrical quick-action couplings for maximum working
pressures of 1 MPa, 1,6 MPa, and 2,5 MPa (10 bar, 16 bar and 25 bar) — Plug connecting dimensions,
specifications, application guidelines and testing
ISO 7638-1:2018, Road vehicles — Connectors for the electrical connection of towing and towed vehicles —
Part 1: Connectors for braking systems and running gear of vehicles with 24 V nominal supply voltage
ISO 11992 (all parts), Road vehicles — Interchange of digital information on electrical connections between
towing and towed vehicles
ISO 12098:2020, Road vehicles — Connectors for the electrical connection of towing and towed vehicles —
15-pole connector for vehicles with 24 V nominal supply voltage
ISO 13044-1, Road vehicles — 24 V fully automatic coupling systems (FACS) for heavy commercial vehicle
combinations — Part 1: General requirements and definitions
ISO 16750-3:2012, Road vehicles — Environmental conditions and testing for electrical and electronic
equipment — Part 3: Mechanical loads
ISO 16750-5, Road vehicles — Environmental conditions and testing for electrical and electronic
equipment — Part 5: Chemical loads
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 13044-1 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
fully automated coupling system
FACS
coupling and uncoupling system where all operations, i.e. mechanical, electrical, pneumatic and
applicable auxiliary functions, are performed automatically, enabling the coupling and uncoupling
process to be completed without direct manual intervention
[SOURCE: ISO 13044-1:2012, 3.3.1.3]
3.2
electrical/electronic-pneumatic interface module
EPI module
component, combining all electrical/electronic and pneumatic connections in one mating unit,
consisting of two complementary parts, the EPI plug module (3.2.1) and the EPI socket module (3.2.2)
3.2.1
EPI plug module
part of the EPI module (3.2) containing the electric male contacts, pneumatic male connections and the
alignment pins, it is permanently attached to the king pin side mounted on the semi-trailer (3.2.3)
3.2.2
EPI socket module
part of the EPI module (3.2) containing the electric female contacts, pneumatic female connections and the
alignment sockets, it is permanently attached to the fifth wheel which is mounted to the tractor vehicle
3.2.3
semi-trailer
towed vehicle which is designed to be coupled to either a towing vehicle or to a dolly, and to impose a
substantial vertical load either on the towing vehicle or on the dolly
3.2.4
alignment device
device placed on the trailer-side, which makes contact to the fifth wheel throat during the coupling
process and centres the EPI plug relative to the EPI socket
4 Requirements
4.1 General
In order to guarantee the best functionality, comfort and safety, the use of FACS is recommended in
combination with spring-brake equipped semi-trailers only. FACS does not exonerate the driver from
ensuring the semi-trailer is correctly parked before coupling or uncoupling.
In order to guarantee best functionality, comfort and safety, the use of FACS is recommended for towing
vehicles with height adjustable air-suspension at least on the rear axle.
2 © ISO 2021 – All rights reserved

In the case of coupling systems that are not fully automatic, but utilize an automatic electro-pneumatic
interface, this interface shall conform with the requirements specified within this document.
4.2 Tractor and semi-trailer
In order to ensure interchangeability between tractor vehicles and semi-trailers, the requirements of
ISO 3842 and ISO 1726-1 or ISO 1726-2 shall be met for vehicles to be equipped with FACS.
4.3 Mechanical interface, Manual operation
Fifth wheels installed on FACS-equipped tractor vehicles shall conform with the requirements of
ISO 3842. Fifth wheel coupling pins (king pins) installed on FACS-equipped semi-trailers shall conform
with the requirements of ISO 337. In the event of a failure of the remote control it shall be possible,
in an emergency, to open the coupling in at least one other way. If this requires the use of a tool, then
this shall be included in the vehicle's tool kit. Any manual operation shall not lead to any damages or
malfunction of the system components.
NOTE For fifth wheel versions with a throat angle other than 40° (e.g. 52°) optional versions can be allowed
under the condition that the alignment device (Figure 2, key 2 or Figure 1, key 2) uses a corresponding angle. In
this case the interchangeability will only be ensured within the individual version.
4.4 EPI module
4.4.1 EPI plug modules and EPI socket modules in accordance with this document shall provide the
following electrical connections with 24 V nominal supply voltage:
— 7 poles for the electrical connection of the braking systems and running gear (incl. 2 poles for the
CAN based communication conformant to ISO 11992-1 and ISO 11992−2);
— 23 poles for the electrical connection of equipment other than braking systems and running gear
(incl. 2 poles for the CAN-based communication conformant to ISO 11992-1 and ISO 11992−3).
The dimensional characteristics and location of the EPI module shall be in accordance with the
specifications of Annex A. Number, location and functionality shall be in accordance with the
specifications of Annex B. Electrical contacts shall only be used as specified.
CAUTION — Using the electrical contacts for non-specified purposes (including ground) may
cause damage to equipment. Any deviation from the contact allocation specified in Table 1 is not
allowed. However, depending on legislation and customer demand, only some of the 30 electrical
contacts may be required.
4.4.2 EPI plug modules and EPI socket modules in accordance with this document shall provide
connections for the following two pneumatic braking lines:
— one control line;
— one supply line.
The dimensional characteristics of the pneumatic connections shall be in accordance with the
specifications of Annex A.
4.5 Mating of the two EPI parts
The mating of the EPI plug module and the EPI socket module shall take place automatically during the
coupling process as illustrated in Figure A.1.
4.6 Guiding and alignment
4.6.1 General
The guiding and alignment of the EPI module shall be made by a rigid alignment pin in the middle plus
two outer pins, which are preferably “self-aligning” designed to provide low forces during EPI mating;
see Figure A.5.
The central alignment pin shall have the ability to align both EPI parts within a range ± 5 mm in both
horizontal and vertical directions. The two outer pins shall ensure the parallel orientation of both EPI
parts for connection alignment.
The positional tolerance between the contact surface of the alignment device and the fifth wheel shall
be a maximum of ±2 mm, according to Figure 1.
Dimensions in millimetres
Key
1 fifth wheel
2 alignment device (movable in length direction, shown in contact position, see Figure 2)
3 EPI central alignment socket
Figure 1 — EPI female module positioning tolerance (displaced shown)
4 © ISO 2021 – All rights reserved

Dimensions in millimetres
Key
1 king pin
2 alignment device (movable in length direction, shown in two positions)
3 EPI central alignment pin
Figure 2 — EPI male module positioning tolerance (displaced shown)
4.6.2 Installation requirements of EPI socket module
4.6.2.1 Translational degree of freedom in the longitudinal direction of alignment pin:
4.6.2.1.1 No actuator: Displaceable from 0 mm to a minimum of 30 mm [S , as shown in Figure A.2
c)], preloaded with a force between 250 N to 500 N (as both pneumatic lines are under pressure) when
uncoupled, achieved by means of either elastic elements or other stored energy. With the FACS coupled
the EPI socket module will be pushed forward by S = 15 mm [see Figure A.2 b)] which is the nominal
position. In the coupled position, a movement as described above shall be possible, without the EPI
modules being disconnected or damaged.
4.6.2.1.2 With actuator: The actuator shall move the EPI socket by at least the range described in
4.6.2.1.1.
4.6.2.2 Translational degree of freedom in the lateral direction: essentially fixed.
4.6.2.3 Translational degree of freedom in the vertical direction: essentially fixed.
4.6.2.4 Rotational degree of freedom around the longitudinal axis of EPI tractor alignment socket:
essentially fixed.
4.6.2.5 Rotational degree of freedom around the lateral articulation axis: from horizontal to a minimum
of 12° [EPI module upwards, see Figure A.2 b)].
4.6.2.6 Rotational degree of freedom around the vertical axis: essentially fixed.
4.6.3 Installation requirements of semi-trailer-mounted EPI module
4.6.3.1 Translational degree of freedom in the longitudinal direction of the alignment pin: fixed.
4.6.3.2 Translational degree of freedom in the lateral direction: essentially fixed.
4.6.3.3 Translational degree of freedom in the vertical direction: essentially fixed.
4.6.3.4 Rotational degree of freedom around the longitudinal axis
...