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E/ECE/324
) Rev.1/Add.54/Rev.2/Amend.7
E/ECE/TRANS/505 )
August 29, 2022
STATUS OF UNITED NATIONS REGULATION
ECE 55-01
UNIFORM PROVISIONS CONCERNING THE APPROVAL OF:
MECHANICAL COUPLING COMPONENTS OF COMBINATIONS OF VEHICLES
Incorporating:
00 series of amendments
Date of Entry into Force: 01.03.83
Supplement 1 to the 00 series of amendments
Date of Entry into Force: 12.12.93
01 series of amendments
Date of Entry into Force: 16.09.01
Corr. 1 to the 01 series of amendments
Dated: 13.03.02
Supplement 1 to the 01 series of amendments
Date of Entry into Force: 17.03.10
Supplement 2 to the 01 series of amendments
Date of Entry into Force: 30.01.11
Supplement 3 to the 01 series of amendments
Date of Entry into Force: 13.04.12
Supplement 4 to the 01 series of amendments
Date of Entry into Force: 08.10.15
Corr. 1 to Revision 2 of the Regulation
Date of Entry into Force; 13.03.19
Supplement 5 to the 01 series of amendments
Date of Entry into Force: 08.10.16
Supplement 6 to the 01 series of amendments
Date of Entry into Force: 09.02.17
Supplement 7 to the 01 series of amendments
Date of Entry into Force: 10.02.18
Supplement 8 to the 01 series of amendments
Date of Entry into Force: 29.05.20
Supplement 9 to the 01 series of amendments
Date of Entry into Force: 09.06.21
Corr. 2 to the 01 series of amendments
Date of Entry into Force: 18.04.22
Supplement 10 to the 01 series of amendments
Date of Entry into Force: 22.06.22

---

UN REGULATION No. 55-01
UNIFORM PROVISIONS CONCERNING THE APPROVAL OF MECHANICAL
COUPLING COMPONENTS OF COMBINATIONS OF VEHICLES
CONTENTS
REGULATION
1. Scope
2. Definitions
3. Application for Approval of a Mechanical Coupling Device or Component
4. General Requirements for Mechanical Coupling Devices or Components
5. Application for Approval of a Vehicle fitted with a Mechanical Coupling Device or Component
6. General Requirements for Vehicles fitted with a Mechanical Coupling Device or Component
7. Markings
8. Approval
9. Modifications of the Mechanical Coupling Device or Component, or of the Vehicle and Extension of
Approval
10. Conformity of Production Procedures
11. Penalties for Non-conformity of Production
12. Production Definitively Discontinued
13. Transitional Provisions
14. Names and Addresses of Technical Services Responsible for Approval Tests, and of Type
Approval Authorities

---

1. SCOPE
UN REGULATION No. 55-01
UNIFORM PROVISIONS CONCERNING THE APPROVAL OF MECHANICAL
COUPLING COMPONENTS OF COMBINATIONS OF VEHICLES
1.1. This Regulation lays down the requirements which mechanical coupling devices and
components shall meet in order to be regarded internationally as being mutually compatible.
1.2. This Regulation applies to devices and components intended for:
1.2.1. Motor vehicles and trailers intended to form a combination of vehicles
1.2.1.1. For the purpose of this Regulation a dolly is defined as a towing trailer designed for the sole
purpose to tow a semi-trailer.
1.2.2. Motor vehicles and trailers intended to form articulated vehicles , where the vertical load
imposed on the motor vehicle by the trailer does not exceed 200kN,
1.3. This Regulation applies to:
1.3.1. Standard devices and components as defined in Paragraph 2.3.;
1.3.2. Non-standard devices and components as defined in Paragraph 2.4.;
1.3.3. Non-standard miscellaneous devices and components as defined in Paragraph 2.5.
2. DEFINITIONS
For the purposes of this Regulation:
2.1. "Mechanical Coupling Devices and Components" means all those items on the frame,
load-bearing parts of the bodywork and the chassis of the motor vehicle and trailer by
means of which they are connected together to form the combination of vehicles or the
articulated vehicles. Fixed or detachable parts for the attachment or operation of the
mechanical coupling device or component are included.
2.2. Automatic coupling requirement is achieved if reversing the towing vehicle against the trailer
is sufficient to engage the coupling completely, to lock it automatically and to indicate proper
engagement of the locking devices without any external intervention.
In the case of hook type couplings automatic coupling requirement is achieved if opening
and closing of the coupling locking device takes place without any external intervention
when the drawbar eye is inserted into the hook.
2.3. Standard mechanical coupling devices and components conform to standard dimensions
and characteristic values as given in this Regulation. They are interchangeable within their
class, independent of manufacturer.
2.4. Non-standard mechanical coupling devices and components do not conform in all respects
to the standard dimensions and characteristic values given in this Regulation but can be
connected to standard coupling devices and components in the relevant class.

---

2.6.4.4. Class D50-X Non-standard 50mm pin diameter drawbar eyes.
2.6.5.
Class E
Non-standard drawbars comprising overrun devices
and similar items of equipment mounted on the front
of the towed vehicle, or to the vehicle chassis, which
are suitable for coupling to the towing vehicle by
means of drawbar eyes, coupling heads or similar
coupling devices – see Annex 5, Paragraph 5.
Drawbars may be hinged to move freely, in a vertical plane and not support any vertical load
or be fixed in a vertical plane so as to support a vertical load (Rigid drawbars). Rigid
drawbars can be entirely rigid or be flexibly mounted.
Drawbars may comprise more than one component and may be adjustable or cranked.
This Regulation applies to drawbars which are separate units, not an integral part of the
chassis of the towed vehicle.
2.6.6.
Class F
Non-standard drawbeams comprising all components
and devices between the coupling devices, such as
coupling balls and drawbar couplings, and the frame
(for example the rear cross member), the loadbearing
bodywork or the chassis of the towing vehicle
– see Annex 5, Paragraph 6.
2.6.7.
Class G
Fifth wheel couplings are plate type couplings having
an automatic coupling lock and are fitted to the
towing vehicle for connecting with a 50mm diameter
fifth wheel coupling pin fitted to a semi-trailer – see
Annex 5, Paragraph 7.
2.6.7.1. Class G50 Standard 50mm pin diameter fifth wheel couplings.
2.6.7.2.
Class G50-X
Non-standard
50mm
pin
diameter
fifth
wheel
couplings.
2.6.8.
Class H
Fifth wheel coupling pins, 50mm diameter, are
devices fitted to a semi-trailer to connect with the fifth
wheel coupling of the towing vehicle – see Annex 5,
Paragraph 8.
2.6.8.1.
Class H50-X
Non-standard 50mm pin diameter fifth wheel coupling
pins.
2.6.9. Class J Non-standard mounting plates comprising all
components and devices for attaching fifth wheel
couplings to the frame or chassis of the towing
vehicle. The mounting plate may have provision for
moving horizontally, that is to form a sliding fifth
wheel – see Annex 5, Paragraph 9.
2.6.10.
Class K
Standard, hook type couplings intended for use with
appropriate Class L type toroidal drawbar eyes – see
Annex 5, Paragraph 10.

---

2.11. The characteristic values D, D , S, V and A are defined and verified as:
2.11.1. The D and D value are characteristic performance values for the horizontal forces of the
coupling equipment verified as described in Annex 6 to this Regulation.
2.11.2. The U value is a characteristic performance value for the vertically imposed mass, in
tonnes, on the fifth wheel coupling. This performance value shall be verified as described in
Annex 6 to this Regulation.
2.11.3. The S value is a characteristic performance value for the vertically imposed mass, in
kilograms, to the coupling from a centre axle trailer under static conditions. This
performance value shall be verified as described in Annex 6 to this Regulation.
2.11.4. The V value is a characteristic performance value of the amplitude of the vertical force
imposed on the coupling by a centre axle trailer. This performance value shall be verified as
described in Annex 6 to this Regulation.
2.11.5. The A value is a characteristic performance value for hinged drawbars that sets maximum
permitted axle mass in tonnes of the front steered axle group of a full trailer. This
performance value shall be verified as described in Annex 6 to this Regulation.
2.11.6. To each of the characteristic performance value D, D , U, V and S there are corresponding
application requirement values. Those requirements values are determined according to
Annex 8 to this Regulation.
Figure 1
Dimensions of the Centre Axle Trailer

---

Subscripts:
O
U
A
h
p
= maximum test force
= minimum test force
= static force
= horizontal
= pulsating
res = resultant
s
w
= vertical
= alternating force
2.13. "Centre axle trailer" means a trailer having a drawbar which cannot move in a vertical
plane independent of the trailer and having an axle or axles positioned close to the centre of
gravity of the trailer, when uniformly loaded. The vertical load imposed on the coupling of
the towing vehicle shall not exceed 10% of the maximum mass of the trailer, or 1,000kg,
whichever is the lesser.
The maximum mass of the centre axle trailer means the total mass transmitted to the
ground by the axle or axles of the trailer when coupled to a towing vehicle and when loaded
to the technically permissible maximum mass .
2.14. "Positive mechanical engagement" means that the design and geometry of a device and
its component parts shall be such that it will not open or disengage under the action of any
forces or components of forces to which it is subject during normal use or testing.
2.15. "Vehicle type" means vehicles which do not differ in such essential respects as the
structure, dimensions, shape and materials in areas to which the mechanical coupling
device or component is affixed. This applies to both the towing vehicle and trailer.
2.16. "Secondary coupling device" means a chain, wire rope, etc., fitted a coupling device,
capable in the event of separation of the main coupling, of ensuring that the trailer remains
connected to the towing vehicle and that there is some residual steering action.

---

4. GENERAL REQUIREMENTS FOR MECHANICAL COUPLING DEVICES OR
COMPONENTS
4.1. Each sample shall conform to the dimensional and strength specifications set out in
Annexes 5 and 6. Following the tests specified in Annex 6 there shall not be any cracks,
fractures or any excessive permanent distortion which would be detrimental to the
satisfactory operation of the device or component.
4.2. All parts of the mechanical coupling device or component whose failure could result in
separation of the vehicle and trailer shall be made of steel. Other materials may be used
provided that equivalence has been demonstrated by the manufacturer to the satisfaction of
the Type Approval Authority or Technical Service of the Contracting Party applying this
Regulation.
4.3. The mechanical coupling devices or components shall be safe to operate and coupling and
uncoupling shall be possible by one person without the use of tools. With the exception of
Class T couplings only devices which allow automatic coupling shall be allowed for the
coupling of trailers having a maximum technically permissible mass greater than 3.5t.
4.4. The mechanical coupling devices or components shall be designed and manufactured such
that in normal use and with correct maintenance and replacement of wearing parts they will
continue to function satisfactorily and retain the characteristics prescribed by this
Regulation.
4.5. All mechanical coupling devices or components shall be designed to have positive
mechanical engagement and the closed position shall be locked at least once by further
positive mechanical engagement unless further requirements are stated in Annex 5.
Alternatively there may be two or more separate arrangements to ensure the integrity of the
devices but each arrangement shall be designed to have positive mechanical engagement
and shall be tested individually to any requirements given in Annex 6. Positive mechanical
engagement shall be as defined in Paragraph 2.14.
Spring forces may be used only to close the device and to prevent the effects of vibration
from causing component parts of the device to move to positions where it may open or
disengage.
The failure or omission of any one single spring shall not allow the complete device to open
or disengage.
4.6. Every device or component shall be accompanied by installation and operating instructions
giving sufficient information for any competent person to install it correctly on the vehicle
and operate it properly – see also Annex 7. The instructions shall be in at least the language
of the country in which it will be offered for sale. In the case of devices and components
supplied for original equipment fitting by a vehicle manufacturer or bodybuilder, installation
instructions may be dispensed with but the vehicle manufacturer or bodybuilder will be
responsible for ensuring that the vehicle operator is supplied with the necessary instructions
for correct operation of the coupling device or component.

---

5. APPLICATION FOR APPROVAL OF A VEHICLE FITTED WITH A MECHANICAL
COUPLING DEVICE OR COMPONENT
5.1. Where a vehicle manufacturer applies for approval of a vehicle fitted with a mechanical
coupling device or component or authorises the use of a vehicle for towing any form of
trailer, then, at the request of a bona fide applicant for possible type approval for a
mechanical coupling device or component, or of the Type Approval Authority or Technical
Service of a Contracting Party, the vehicle manufacturer shall readily make available to that
inquirer or Authority or Technical Service, such information as required in Annex 2,
Appendix 1, to enable a manufacturer of a coupling device or component to properly design
and manufacture a mechanical coupling device or component for that vehicle. At the request
of a bona fide applicant for possible type approval for a mechanical coupling device or
component, any information given in Annex 2, Appendix 1 which is held by the Type
Approval Authority shall be released to that applicant.
5.2. The application for approval of a vehicle type with regard to the fitting of a mechanical
coupling device or component shall be submitted by the vehicle manufacturer or by his duly
accredited representative.
5.3. It shall be accompanied by the following information to enable the Type Approval Authority
to complete the communication form given in Annex 2.
5.3.1. A detailed description of the vehicle type according to Annex 2, Appendix 1 and of the
mechanical coupling device or component and, at the request of the Type Approval
Authority or Technical Service, a copy of the approval form for the device or component;
5.3.2. Deleted.
5.3.2.1. Deleted.
5.3.3. Three sets of drawings which are sufficiently detailed to identify the device or component
and which specify how it is to be fitted to the vehicle; the drawings shall show the position
and space provided for the approval number and other marking as given in Paragraph 7.;
5.3.4. A detailed technical description of the device or component, specifying, in particular, the
type and the materials used;
5.3.5. A statement of the characteristic performance values of D, D , S, V and U as applicable and
as defined in Paragraph 2.11.;
5.3.5.1. The characteristic performance values of the coupling equipment installed on the vehicle
shall be verified according to Annex 8 to this Regulation applying the maximum permissible
towing vehicle, trailer and combination masses.
5.3.6. A vehicle, representative of the type to be approved and fitted with a mechanical coupling
device, shall be submitted to the Type Approval Authority or Technical Service which may
also request additional samples of the device or component;
5.3.7. A vehicle not having all of the components appropriate to the type may be accepted
provided that the applicant can show, to the satisfaction of the Type Approval Authority or
Technical Service, that the absence of the components does not have any effect on the
results of the inspection as far as the requirements of this Regulation are concerned.

---

8. APPROVAL
8.1. If the sample(s) of a type of mechanical coupling device or component meets (meet) the
requirements of this Regulation, approval shall be granted subject to the requirements of
Paragraph 10 being satisfactorily met.
8.2. An approval number shall be assigned to each type approved. Its first two digits (at present
01) shall indicate the series of amendments incorporating the most recent major technical
amendments made to the Regulation at the time of issue of the approval. The same
Contracting Party may not assign the same number to another type of device or component
referred to in this Regulation.
8.3. Notice of approval or of extension, refusal or withdrawal of approval or of production
definitely discontinued, relating to a type of mechanical coupling device or component
approved pursuant to this Regulation, shall be communicated to the Parties to the
1958 Agreement applying this Regulation, by means of a communication form conforming to
the model in either Annex 1 or Annex 2 to this Regulation.
8.4. In addition to the mark prescribed in Paragraph 7.1., there shall be affixed to every
mechanical coupling device or component approved under this Regulation, in the space
referred to in Paragraph 7.2., an approval mark as described in Paragraph 8.5.
8.5. The approval mark shall be an international approval mark comprising:
8.5.1. A circle surrounding the Letter "E", followed by the distinguishing number of the country
which has granted approval,
8.5.2. The approval number prescribed in Paragraph 8.2.;
8.5.3. The approval mark and number shall be arranged as shown in the example in Annex 3.
9. MODIFICATIONS OF THE MECHANICAL COUPLING DEVICE OR COMPONENT, OR OF
THE VEHICLE AND EXTENSION OF APPROVAL
9.1. Any modification to the type of mechanical coupling device or component, or of the vehicle
as defined in Paragraph 2.10. shall be notified to the Type Approval Authority or technical
service which granted the approval. The Type Approval Authority or Technical Service may
then either:
9.1.1. Consider that the modifications are unlikely to have any appreciable adverse effect and that
in any case the device, component or vehicle still conforms to requirements; or
9.1.2. Require a further test report.
9.2. Confirmation of, or refusal of approval, specifying the modification, shall be communicated
by the procedure prescribed in Paragraph 8.3. to the Contracting Parties applying this
Regulation.
9.3. The Type Approval Authority or Technical Service issuing an extension of approval shall
assign a series number for such an extension and shall inform the other Contracting Parties
applying this Regulation by the procedure prescribed in Paragraph 8.3.

---

14. NAMES AND ADDRESSES OF TECHNICAL SERVICES RESPONSIBLE FOR
APPROVAL TESTS, AND OF TYPE APPROVAL AUTHORITIES
14.1. The Contracting Parties to the 1958 Agreement applying this Regulation shall communicate
to the United Nations Secretariat the names and addresses of the Technical Services
responsible for conducting approval tests and of the Type Approval Authorities which grant
approval and to which forms certifying approval or extension or refusal or withdrawal of
approval, or production definitively discontinued, issued in other countries, are to be sent.

---

9.2. Characteristic values: ...................................................................................................................
9.2.1. Primary values: .............................................................................................................................
D ................................... kN
D ................................ kN
S .................................. kg
U ............................. tonnes
V .................................. kN
Alternative values:
D ................................... kN
D ................................ kN
S .................................. kg
U ............................. tonnes
V .................................. kN
9.3. For Class A mechanical coupling devices or components, including towing brackets:
Maximum permissible vehicle mass as declared by the vehicle manufacturer's: .................... kg
Distribution of maximum permissible vehicle mass between the axles: .......................................
Vehicle manufacturer's maximum permissible towable trailer mass: ....................................... kg
Vehicle manufacturer's maximum permissible static mass on coupling ball: ........................... kg
Maximum mass:
Maximum mass of the vehicle, with bodywork, in running order, including coolant, oils, fuel,
tools and spare wheel (if supplied) but not including driver: .................................................... kg
Loading condition under which the tow ball height of a mechanical coupling device fitted to
Category M vehicles is to be measured – see Paragraph 2 of Annex 7, Appendix 1:
......................................................................................................................................................
9.4. For Class B coupling heads, is the coupling head intended to be fitted to an unbraked O
trailer: ........................................................................................................................... Yes/No
10. Instructions for the attachment of the coupling device or component type to the vehicle and
photographs or drawings of the mounting points (see Annex 2, Appendix 1) given by the
vehicle manufacturer: ...................................................................................................................
11. Information on the fitting of any special reinforcing brackets or plates or spacing
components necessary for the attachment of the coupling device or component (see Annex 2,
Appendix 1): ..................................................................................................................................
12. Additional information where the use of the coupling device or component is restricted to
special types of vehicles – see Annex 5, Paragraph 3.4.:
......................................................................................................................................................
13. For Class K hook type couplings, details of the drawbar eyes suitable for use with the
particular hook type: .....................................................................................................................

---

ANNEX 2
COMMUNICATION
(Maximum format: A4 (210 x 297mm))
issued by:
Name of administration
.............................................
.............................................
.............................................
concerning:
APPROVAL GRANTED
APPROVAL EXTENDED
APPROVAL REFUSED
APPROVAL WITHDRAWN
PRODUCTION DEFINITIVELY DISCONTINUED
of a vehicle type with regard to the fitting of a mechanical coupling device or component pursuant to
Regulation No. 55
Approval No. ...................
Extension No.....................
1. Trade name or mark of vehicle: ....................................................................................................
2. Vehicle type: .................................................................................................................................
3. Manufacturer's name and address: ..............................................................................................
......................................................................................................................................................
4. If applicable, name and address of the manufacturer's representative: .......................................
......................................................................................................................................................
5. Vehicle category, for example, M , N : ......................................................................................

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16. Approval mark position: ................................................................................................................
17. Reason(s) for extension of approval: ...........................................................................................
18. Approval granted/extended/refused/withdrawn:
19. Place: ............................................................................................................................................
20. Date: .............................................................................................................................................
21. Signature: .....................................................................................................................................
22. The list of documents deposited with the Type Approval Authority which has granted approval
is annexed to this communication and may be obtained on request.
23. Remarks: .....................................................................................................................................

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3.3. For every fixing point the following shall be specified (if applicable):
(a)
(b)
(c)
(d)
(e)
(f)
(g)
The location of each hole to be drilled in the chassis or the body of the vehicle
(specification of the maximum diameter to be drilled);
The location and size of pre-drilled holes (specification of the diameter of the hole);
The location and size of captive nuts or bolts (specification of the thread size, quality);
The material to be used for attachment (e.g. securing bolts, washers etc.);
Any additional mounting point to be used for the attachment of coupling devices
(e.g. the towing eye);
The specification of the dimensions shall be specified with an accuracy of at least
±1mm;
The vehicle manufacturer may specify other specifications with regard to the fitting of
the coupling device (e.g. size and thickness of back plates).
4. VEHICLE MANUFACTURER'S NAME AND ADDRESS.

---

ANNEX 4
EXAMPLES OF ARRANGEMENTS OF MARKING OF THE CHARACTERISTIC VALUES
1. All mechanical coupling devices or components shall be marked with the class of the device or
component. In addition there shall be marking to indicate the capacity in terms of characteristic
values as defined in Paragraph 2.11. of this Regulation.
1.1. The height of all letters and numbers shall be not less than those of the approval number, that
is a/3 where a is 8mm minimum.
1.2. The characteristic values applicable to each device or component which are to be marked are
as shown in the table below – see also Paragraph 7.3. of this Regulation:
Description of mechanical
coupling device or component
Coupling balls and towing
brackets – see Annex 5,
Paragraph 1 of this Regulation
Table 1
Relevant Characteristic Values to be Marked
on Coupling Devices or Components
Relevant characteristic values to be marked
Class D D S U V
� � �
Coupling heads � � �
Drawbar couplings � � � � �
Drawbar eyes � � � � �
Drawbars � � � � �
Drawbeams � � � � �
Fifth wheel couplings � � �
Fifth wheel pins � �
Fifth wheel mounting plates � � �
Hook type couplings � � � � �
Examples:
C50-X D130 D 90 S1000 V35 would identify a non-standard drawbar coupling of
Class C50-X with a maximum D value of 130kN, a maximum permitted D value of 90kN,
a maximum permitted static vertical imposed mass of 1,000kg and a maximum permitted
V value of 35kN.
A50-X D20 S120 would identify a standard towing bracket with ball coupling of
Class A50-X with a maximum D value of 20kN and a maximum permitted static vertical
imposed mass of 120kg.

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1.2. The shape and dimensions of towing brackets shall meet the requirements of the vehicle
manufacturer concerning the attachment points and additional mounting devices or
components, see Annex 2, Appendix 1.
1.3. Removable Coupling Balls:
1.3.1. In the case of removable coupling balls or components which are not fixed by bolts, for
example Class A50-X, the point of connection and the locking arrangement shall be designed
for positive mechanical engagement.
1.3.2. In the case of a removable coupling ball or component which may be separately approved for
use with a variety of towing brackets for different vehicle applications, for example
Class A50-X, the clearance space when such a coupling ball is fitted to the towing bracket
shall be that prescribed in Annex 7, Figure 25.
1.4. Movable Coupling Devices (couplings that can be moved without separation)
A movable coupling device shall be designed for positive mechanical engagements in service
position. In case of manual movement the actuating force shall not supersede 20daN. The
movement shall be limited by mechanical end stops.
1.5. Coupling balls and towing devices shall be able to satisfy the tests given in Annex 6,
Paragraph 3.1. or Paragraph 3.10. according to the choice of the manufacturer. However, the
requirements given in Paragraphs 3.1.7. and 3.1.8. are always applicable.
1.6. Special requirements for standard coupling balls and flange type towing brackets of
Classes A50-1 to A50-5 inclusive:
1.6.1. Dimensions of Class A50-1 coupling balls and flange type towing brackets shall be as given in
Figure 3 and Table 2.
1.6.2. Dimensions of Class A50-2, A50-3, A50-4 and A50-5 coupling balls and flange type towing
brackets shall be as given in Figure 4 and Table 2.
1.6.3. Coupling balls and flange type towing brackets of the Classes A50-1 to A50-5 inclusive, shall
be suitable and tested for the characteristic values given in Table 3.

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Table 2
Dimensions of Standard Flange Type Ball Couplings (mm)
see Figures 3 and 4
Class A50-1
A50-2,
A50-4
A50-3,
A50-5
Comments
e 90 83 120 ± 0.5
e � 56 55 ± 0.5
d 17 10.5 15 H13
f 130 110 155 +6.0 - 0
g 50 85 90 +6.0 – 0
c 15 15 15 maximum
l 55 110 120 ± 5.0
h 70 80 80 ± 5.0
Table 3
Minimum Characteristic Values for Standard Flange Type Ball Couplings
Class A50-1 A50-2 A50-3 A50-4 A50-5
D 17 20 30 20 30
S 120 120 120 150 150
D = D value (kN)
S = Static mass (kg)
1.7. Manufacturers of coupling balls and towing brackets intended for fitment in the after-market
and which do not have any association with the relevant vehicle manufacturer shall be aware
of the requirements for articulation of the coupling given in Paragraph 2 of this Annex and
shall comply with the appropriate requirements in Annex 7 to this Regulation.
2. COUPLING HEADS
2.1. Coupling heads of Class B50 shall be designed so that they can be used safely with the
coupling balls described in Paragraph 1 of this Annex and thereby retain the prescribed
characteristics.
Coupling heads shall be designed in such a way that safe coupling is ensured, also taking
into account the wear of the coupling devices.
2.2. Coupling heads shall be able to satisfy the tests laid down in Annex 6, Paragraph 3.2.
2.3. Any additional device (e.g. braking, stabiliser, etc.) shall not have any adverse effect on the
mechanical connection.

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The minimum required size of the jaw depends on the D value of the coupling:
D value �18kN � width 150mm, height 100mm
D value >18kN �25kN � width 280mm, height 170mm
D value >25kN � width 360mm, height 200mm
The external corners of the jaw may be radiused.
Smaller jaws are permitted for Class C50-X drawbar couplings if their use is restricted to
centre axle trailers up to 3.5t maximum permissible mass or if the use of a jaw from the above
table is impossible due to technical reasons and if, furthermore, there are special
circumstances such as visual aids for ensuring safe execution of the automatic coupling
procedure and if the field of application is restricted in the approval according to information
given by the coupling manufacturer in the communication form shown in Annex 1.
3.4. Minimum Articulation of the Coupled Drawbar Eye
The drawbar eye, when coupled to a drawbar coupling but not fitted to a vehicle, shall have
the degrees of articulation given below. If part of the articulation is provided by a special joint
(Class C50-X drawbar couplings only), the field of application, given in the communication
form shown in Annex 1, shall be restricted to the cases stated in Annex 7, Paragraph 1.3.8.
Any flexible components providing part of the articulation are not considered to be a special
joint.
3.4.1. ±90° horizontally about the vertical axis from the longitudinal axis of the vehicle –
see Figure 5.
Figure 5
Horizontal Rotation of the Coupled Drawbar Eye

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3.5. Locking to Prevent Inadvertent Uncoupling:
In the closed position the coupling pin shall be locked by two positive mechanical
engagement locking devices each of which shall remain effective should the other fail.
The closed and locked position of the coupling shall be clearly indicated externally by a
mechanical device. It shall be possible to verify the position of the indicator by feel, for
example, in the dark.
The mechanical indication device shall indicate the engagement of both locking devices (an
AND condition).
However, it is sufficient for the engagement of only one locking device to be indicated if, in
this situation, engagement of the second locking device is an inherent feature of the design.
3.6. Opening Devices
3.6.1. Hand Levers
Hand levers shall be of a design suitable for easy use with the end rounded off. The coupling
shall not have any sharp edges or points of possible pinching near the hand lever which could
result in injury during operation of the coupling. The force needed to release the coupling,
measured without the drawbar eye, shall not exceed 250N perpendicular to the hand lever
along the line of operation.
3.6.2. Remote Control
For installations with remote control, Paragraph 12.3.6. of Annex 5 applies.
3.7. Special Requirements for Standard Drawbar Couplings of Classes C50-1 to C50-6:
3.7.1. The swivel motion of the drawbar eye about the transverse axis shall be achieved through the
spherical shape of the coupling pin (and not by means of a joint);
3.7.2. Tensile and compressive shock loads along the longitudinal axis due to the clearance
between the coupling pin and the drawbar eye shall be attenuated by spring and/or damping
devices (except Class C50-1).
3.7.3. The dimensions shall be as given in Figure 8 and Table 4.
3.7.4. The couplings shall be suitable and tested for the characteristic values given in Table 5.

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Table 4
Dimensions of Standard Drawbar Couplings (mm)
see Figure 8
Class C50-1 C50-2 C50-3 C50-4 C50-5
C50-6
C50-7
Remarks
e 83 83 120 140 160 160 ±0.5
e 56 56 55 80 100 100 ±0.5
d � 54 74 84 94 94 maximum
d 10.5 10.5 15 17 21 21 H13
f 110 110 155 180 200 200 +6.0 -0
g 85 85 90 120 140 140 ±3.0
a 100 170 200 200 200 200 +20.0 – 0
b 150 280 360 360 360 360 +20.0 – 0
c 20 20 24 30 30 30 maximum
h 150 190 265 265 265 265 maximum
l � 150 250 300 300 300 maximum
l 150 300 330 330 330 330 maximum
l 100 160 180 180 180 180 ±20.0
T � 15 20 35 35 35 maximum
Table 5
Minimum Characteristic Values for Standard Drawbar Couplings
Class
C50-1
C50-2
C50-3
C50-4
C50-5
C50-6
C50-7
D
18
25
70
100
130
190
190
D
18
25
50
70
90
120
130
S
200
250
650
900
1,000
1,000
1000
V
12
10
18
25
35
50
75
D
=
D value (kN)
D
=
D value (kN) for centre axle trailer applications
S
=
Static vertical load on coupling (kg)
V
=
V value (kN)

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Figure 10
Non-slotted Sleeve for Class D50-C Drawbar Eyes
Table 6
Dimensions for Drawbar Eyes D50-A and D50-X,
see Figure 11
Class
h (mm)
b (mm)
D50-A
65 +2/ -1
60 +2/ -1
D50-X
80 maximum
62 maximum
Table 7
Minimum Characteristic Values for Standard Drawbar Eyes
Class
D
D
S
V
D50-A
130
90
1,000
30
D50-B
130
90
1,000
25
D50-C
190
120
1,000
50
D50-D
190
130
1,000
75

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4.2.2. Class D50-B drawbar eyes shall have the dimensions illustrated in Figure 12.
Figure 12
Dimensions of Class D50-B Drawbar Eyes,
see other dimensions in Figure 11

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4.4. General Requirements for Class L Toroidal Drawbar Eyes:
4.4.1. Class L toroidal drawbar eyes are intended for use with Class K hook type couplings
4.4.2. When used with a Class K hook type coupling they shall meet the requirements for
articulation given in Paragraph 10.2 of this Annex.
4.4.3. Class L toroidal drawbar eyes shall have the dimensions given in Figure 14 and Table 8
Figure 14
Dimensions of Class L Toroidal Drawbar Eyes
see Table 8

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5.3.4. The height adjusting devices shall not interfere with the action of any inertia, overrun type,
brake.
5.4. In the case of drawbars combined with inertia, overrun, brakes, the distance between the
centre of the drawbar eye and the end of the free shank of the drawbar eye shall not be less
than 200mm in the brake application position. With the shank of the drawbar eye fully inserted
the distance shall not be less than 150mm.
5.5. Drawbars for use on centre axle trailers shall possess at least half the moment of resistance
against lateral forces as against vertical forces.
6. DRAWBEAMS
6.1. Drawbeams of Class F shall satisfy the tests prescribed in Annex 6, Paragraph 3.3.
6.2. The drilling pattern for mounting of Class C standard drawbar couplings shall be in
accordance with Figure 15 and Table 10 below.
6.3. Drawbeams shall not be welded to the chassis, bodywork or other part of the vehicle.
Figure 15
Mounting Dimensions for Standard Drawbar Couplings
(see Table 10)

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Notes
Figure 16
Dimensions of Standard Fifth Wheel Couplings
(see Table 11)

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7.4. Locking Devices to Prevent Uncoupling of Fifth Wheel Couplings
The fifth wheel coupling shall be locked in the coupled position by two positive mechanical
locking devices each of which shall remain effective should the other fail.
The primary locking device shall operate automatically but the secondary locking device may
either be automatic or be engaged manually. The secondary locking device may be designed
to work in conjunction with the primary device and provide an additional positive mechanical
lock for the primary device. It shall only be possible to engage the secondary locking device if
the primary device is properly engaged.
It shall not be possible for the locking devices to be released inadvertently. Release shall
require intentional action by the driver or operator of the vehicle.
The closed and locked position of the coupling shall be indicated visually by a mechanical
device and it shall be possible to verify the position of the indicator by feel, for example, to
allow the position to be checked during darkness. The indication device shall indicate the
engagement of both primary and secondary locking devices, however, it is sufficient for the
engagement of only one device to be indicated if, in this case, the engagement of the other
device is a simultaneous and inherent feature of the design.
7.5. Operating Devices or Release Mechanisms
In the closed position the operating devices or release mechanisms shall be prevented from
being operated inadvertently or accidentally. The locking system shall be such as to require
positive, conscious action to release the locking device in order to operate coupling release
mechanism.
7.6. Surface Finish
The surfaces of the coupling plate and coupling lock shall be functionally satisfactory and be
carefully machined, forged, cast or pressed.
7.7. Load Requirements
All fifth wheel couplings shall be able to satisfy the tests described in Annex 6, Paragraph 4.7.

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8. FIFTH WHEEL COUPLING PINS
8.1. Fifth wheel coupling pins of Class H50 (ISO 337) shall have the dimensions shown in
Figure 18.
Figure 18
Dimensions of Class H50 Fifth Wheel Coupling Pins
8.2. The coupling pins shall be able to satisfy the tests described in Annex 6, Paragraph 3.9.
9. MOUNTING PLATES
9.1. Class J mounting plates for fifth wheel couplings shall have circular mounting holes positioned
as shown in Figure 16a if they are intended for standard fifth wheel couplings. However, the
mounting holes shall be 17mm +2.0mm/-0.0mm diameter. The holes shall be circular, NOT
slotted (see Figure 16a).
9.2. Mounting plates for standard fifth wheel couplings shall be suitable for the positive steering of
semi-trailers (with steering wedges). Mounting plates for non-standard fifth wheel couplings
which are unsuitable for positive steering shall be marked appropriately.
9.3. Mounting plates for fifth wheel couplings shall be able to satisfy the tests described in
Annex 6, Paragraph 3.8.

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10.2. A Class K coupling when used with a Class L toroidal eye, but not fitted to a vehicle, shall
have the following non-simultaneous angles of articulation – see also Figure 19:
10.2.1. ±90° horizontally about the vertical axis of the coupling;
10.2.2. ±40° vertically about the horizontal transverse axis of the coupling;
10.2.3. ±20° axial rotation about the horizontal longitudinal centre line of the coupling.
10.3. Automatic Class K hook type couplings shall have a jaw designed such that the drawbar eye
is guided into the coupling.
10.4. Locking to Prevent Inadvertent Uncoupling:
In the closed position the coupling shall be locked by two positive mechanical engagement
locking devices each of which shall remain effective should the other fail.
The closed and locked position of the coupling shall be clearly indicated externally by a
mechanical device. It shall be possible to verify the position of the indicator by feel, for
example, in the dark.
The mechanical indication device shall indicate the engagement of both locking devices (an
AND condition).
However, it is sufficient for the engagement of only one locking device to be indicated if, in
this situation, engagement of the second locking device is an inherent feature of the design.
10.5. Hand Levers
Hand levers shall be of a design suitable for easy use with the end rounded off. The coupling
shall not have any sharp edges or points of possible pinching near the hand lever which could
result in injury during operation of the coupling. The force needed to release the coupling,
measured without the drawbar eye, shall not exceed 250N perpendicular to the hand lever
along the line of operation.

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11.4. Class T Couplings shall not be Automatic in Operation
11.5. Class T couplings shall satisfy the relevant test requirements given in Annex 6,
Paragraph 3.3., except Paragraph 3.3.4.
11.6. The following minimum and simultaneous angles of articulation shall be possible with the
coupling not fitted to a vehicle but assembled, and in the same normal position as when fitted
to a vehicle;
11.6.1. ±90° horizontally about the vertical axis;
11.6.2. ±8° vertically about the horizontal transverse axis;
11.6.3. ±3° axial rotation about the horizontal longitudinal axis.
12. DRAWBAR TYPE COUPLINGS – CLASS W
12.1. Devices for remote indication and remote control are permitted only on automatic drawbar
couplings and automatic fifth wheel couplings.
Devices for remote indication and remote control shall not interfere with the minimum free
movement of the coupled drawbar eye or coupled semitrailer. They shall be permanently
fitted to the vehicle.
All the devices for remote indication or remote control fall within the scope of testing and
approval of the coupling device together with all parts of the operating devices and
transmission devices.
12.1.1. Class W couplings shall as part of an automated sequence of actions automatically
mechanically connect the two vehicles and establish the electric and pneumatic braking
transmission connection.
12.1.2. Class W couplings shall, as part of an automated sequence of actions, automatically break
the electric and pneumatic braking transmission connection and mechanically disconnect the
two vehicles.
12.2. Class W couplings shall satisfy the relevant test requirements given in Annex 6,
Paragraph 3.3., with the exception of Paragraph 3.3.4. The closure and any locking devices
shall be tested by means of a static force of 0.25D acting in the direction of opening. The test
shall not cause the closure to open. The locking device shall be fully functional after the test.
A test force of 0.1D is sufficient in the case of cylindrical coupling pins.
12.3. The following minimum and simultaneous angles of articulation shall be possible with the
coupling not fitted to a vehicle but assembled, coupled, and in the same normal position as
when fitted to a vehicle:
12.3.1. ±90° horizontally about the vertical axis;
12.3.2. ±20° vertically about the horizontal transverse axis;
12.3.3. ±25° axial rotation about the horizontal longitudinal axis.

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13.3. Remote Control
13.3.1. If a remote control device, as defined in Paragraph 2.8 of this Regulation, is employed, there
shall also be a remote indication device as described in Paragraph 13.2.
13.3.2. There shall be a dedicated switch (i.e. master switch, lever or valve) to enable the coupling to
be opened or closed by means of the remote control device. If this master switch is not
located in the driving cab it shall not be in a position where it is freely accessible to
unauthorised persons or it shall be lockable. The actual operation of the coupling from the
driving cab may only be possible when inadvertent operation has been precluded, for
example by an operation requiring the use of two hands.
It shall be possible to ascertain whether opening of the coupling under remote control has
been completed or not.
13.3.3. If remote control involves the coupling being opened by external force, the condition under
which the external force acts on the coupling shall be indicated appropriately to the
driver. This is not necessary if the external force is only operative while the remote control is
operating.
13.3.4. If the actuating device for opening the coupling under remote control is mounted externally on
the vehicle it shall be possible to oversee the area between the coupled vehicles, but it shall
not be necessary, however, to enter this area in order to operate it.
13.3.5. Any single error in operation or the occurrence of any single fault in the system shall not result
in accidental opening of the coupling during normal road use. Any faults in the system shall
be indicated directly or be immediately obvious at the next operation e.g. by a malfunction.
13.3.6. 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 vehicle's tool kit. The requirements of Paragraph 3.6 of this Annex are not
applicable to hand levers used exclusively for opening the coupling in an emergency.
13.3.7. The remote control devices shall be permanently and clearly identified.

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1.7. Any positive locking device, which is retained in position by spring force, shall remain in its
secured position when subjected to a force applied in the least favourable direction and
equivalent to three times the mass of the locking mechanism.
2. TEST PROCEDURES
In case the test procedure according to Paragraph 3.10. of this Annex is used,
Paragraphs 2.1., 2.2., 2.3. and 2.5. are not applicable.
2.1. For the dynamic tests and static tests, the sample shall be placed in a suitable rig with a
means of force application, such that it is not subjected to any additional forces or moments
apart from the specified test force. In the case of alternating tests, the direction of force
application shall not deviate by more than ±1° from the specified direction. In the case of
pulsating and static tests, the angle shall be set for the maximum test force. This will normally
require a joint at the point of force application (i.e. the point of coupling) and a second joint an
adequate distance away.
2.2. The test frequency shall not exceed 35Hz. The selected frequency shall be well separated
from resonance frequencies of the test set up including the tested device. With asynchronous
testing the frequencies of the two force components shall be between approximately 1% and
a maximum of 3% apart. For coupling devices made from steel the number of stress cycles is
2 × 10 . For devices made from materials other than steel a higher number of cycles may be
necessary. The dye-penetration method of crack testing or an equivalent method shall be
used to determine any cracking during test.
2.3. With pulsating tests, the test force varies between the maximum test force and a lower,
minimum, test force, which may not be greater than 5% of the maximum test force unless
otherwise stated in the specific testing procedure.
2.4. With static tests, other than the special tests required by Paragraph 3.2.3 of this Annex, the
test force shall be applied smoothly and quickly and be maintained for at least 60s.
2.5. The coupling devices or component on test should normally be mounted as rigidly as possible
on a test rig in the actual position in which they will be used on the vehicle. The fixing devices
should be those specified by the manufacturer or applicant and should be those intended for
the attachment of the coupling device or component to the vehicle and/or shall have identical
mechanical characteristics.
2.6. Coupling devices or components shall be tested in the form used on the road. However, at
the discretion of the manufacturer, and in agreement with the Technical Service, flexible
components may be neutralised if this is necessary for the test procedure and if this will not
have any unrealistic influence on the test result.
Flexible components which are overheated during these accelerated test procedures may be
replaced during the test. The test loads may be applied by means of special slack-free
devices.

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3.1.2. The basic test is a dynamic endurance test. The test sample comprises the coupling ball, the
ball neck and the mountings necessary for attaching the assembly to the vehicle. The
coupling ball and towing bracket shall be rigidly mounted to a test rig, capable of producing an
alternating force, in the actual position in which it is intended for use.
3.1.3. The positions of the fixing points for attaching the coupling ball and towing bracket are
specified by the vehicle manufacturer (see Annex 2, Appendix 1 of this Regulation).
3.1.4. The devices submitted for test shall be provided with all parts and design details which may
have an influence on the strength criteria (for example electrical socket plate, any marking,
etc.). The test sample shall include all parts up to the anchorage points or fitting points to the
vehicle. The geometric location of the coupling ball and the fixing points of the coupling device
related to the reference line shall be provided by the vehicle manufacturer and shall be shown
in the test report. All relative positions of the anchorage points with respect to the reference
line, for which the towing vehicle manufacturer shall provide all the necessary information to
the towing device manufacturer, shall be repeated on the test bed.
3.1.5. The sample mounted on the test rig shall be subjected to an alternating stress test applied at
an angle to the ball as shown in Figure 21 or 22.
The direction of the angle of test shall be determined by the vertical relationship between a
horizontal reference line passing through the centre of the ball and a horizontal line passing
through the fixing point of the coupling device which is the highest of the nearest, when
measured in a horizontal plane, to a transverse vertical plane passing through the centre of
the ball. If the fixing point line is above the horizontal reference line, the test shall be carried
out at an angle of α = +15° ± 1° and if it is below then the test shall be carried out at an angle
of α = -15° ± 1° (see Figure 21). The fixing points to be considered in determining the angle of
test shall be those declared by the vehicle manufacturer and which transmit the major towing
forces to the structure of the towing vehicle.
This angle is chosen in order to take account of the vertical static and dynamic load and is
only applicable for a permitted static vertical load not exceeding:
S = 120 × D [N]
Where the static vertical load exceeds that calculated above, the angle shall, in both
conditions, be increased to 20°.
The dynamic test shall be performed with the following test force:
F = ±0.6 D

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3.1.6.2. Coupling balls, comprising parts which can be dismantled.
The following categories are defined:
(a)
(b)
(c)
(d)
Towing bracket and ball (see Figure 20c),
Towing bracket and ball on integral support (see Figure 20d),
Towing bracket with detachable ball (see Figure 20e),
Towing bracket without ball (see Figure 20f).
3.1.6.2.1. The strength test for the devices shown in Figures 20c to 20f shall be carried out according to
the requirements of Paragraph 3.1.5. Dimensions e and f, shall have a manufacturing
tolerance of ±5mm, and shall be stated in the test report.
The test of the towing bracket (see Figure 20f) shall be carried out with a mounted ball (on
support). Account will be taken only of the result of the test on the towing bracket between the
fixing points and the mounting surface of the ball support.
The dimensions e and f shall have a manufacturing tolerance of ±5mm and shall be specified
by the coupling device manufacturer.
3.1.6.3. Coupling devices with variable dimensions e and f for demountable and interchangeable
coupling balls – see Figure 22.
3.1.6.3.1. The strength tests for such towing brackets shall be carried out to the requirements of
Paragraph 3.1.5.
3.1.6.3.2. If a worst case configuration can be defined by agreement between the manufacturer and the
Type Approval Authority or Technical Service, then testing of this one configuration alone
shall be sufficient.
Otherwise, several ball positions shall be tested in a simplified test programme according to
Paragraph 3.1.6.3.3.
3.1.6.3.3. In a simplified test programme, the value for f shall be between a defined value of f
and a
value of f
which does not exceed 100mm. The ball shall be at a distance, e
, of 130mm
from the support. To cover all possible positions of the ball, in the field given by the horizontal
distance from the mounting surface and the vertical range of f (f
to f
), two devices are to
be tested:
(a) One with a ball in the upper (f ) position, and
(b) One with a ball in the lower (f ) position.
The angle of application of the test force will vary, positive or negative, depending on the
relationship of the ball centre horizontal reference line to the parallel line passing through the
highest and nearest coupling device fixing point. The angles to be used are shown in
Figure 22.

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3.2.3. A static separation test shall also be performed. The coupling ball used for the test shall have
a diameter of 49.00 to 49.13mm in order to represent a worn coupling ball. The separation
force, F , shall be applied perpendicular to both the transverse and longitudinal centre line
axes of the coupling head and shall be increased smoothly and quickly to a value of:
and be held for 10s.
F = g(C + S/1,000) kN
The coupling head shall not separate from the ball nor shall any component of the coupling
head exhibit any permanent distortion which could have an adverse effect on its functional
capability.
3.2.4. The secondary coupling device(s) attachment point(s) referred to in Paragraph 4.9. shall
withstand a static force equivalent to 2D with a maximum of 15kN.
3.3. Drawbar Couplings and Drawbeams
3.3.1. An endurance test shall be performed on a test sample. The coupling device shall be
equipped with all the fixings needed to attach it to the vehicle. Any intermediate devices fitted
between the drawbar couplings and the vehicle frame (i. e. drawbeams) shall be tested with
the same forces as the coupling. When testing drawbeams intended for standard drawbar
couplings, the vertical load shall be applied at a longitudinal distance from the vertical plane of
the fixing points that is equal to the position of the corresponding standard coupling.
3.3.2. Drawbar Couplings for Hinged Drawbars (S=0)
The dynamic test shall be performed with a horizontal alternating force of F = ±0.6D acting
in a line parallel to the ground and in the longitudinal median plane of the towing vehicle
passing through the centre of the coupling pin.
3.3.3. Drawbar Couplings for use with Centre-axle Trailers (S>0)
3.3.3.1. Centre axle trailer masses up to and including 3.5t:
Drawbar couplings for use with centre axle trailers up to and including a mass of 3.5t shall be
tested in the same way as coupling balls and towing brackets described in Paragraph 3.1 of
this Annex.
3.3.3.2. Centre axle trailer masses exceeding 3.5t:
The test forces are applied to the specimen in both horizontal and vertical directions in an
asynchronous endurance test. The horizontal line of action shall be equivalent to being
parallel to the ground and along the longitudinal median plane of the towing vehicle and pass
through the centre of the coupling pin. The vertical line of action shall be perpendicular to the
horizontal line of action and shall act along the longitudinal centre line of the coupling pin.
The fixing arrangements for the drawbar coupling and the drawbar eye on the test rig shall be
those intended for its attachment to the vehicle in accordance with the manufacturer’s fitting
instructions.

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3.5. Hook Type Couplings
3.5.1. Class K hook type couplings shall satisfy the dynamic test given in Paragraph 3.5.2 of this
Annex.
3.5.2. Dynamic Test:
3.5.2.1. The dynamic test shall be a pulsating test using a Class L toroidal eye and with the coupling
mounted as it would be on a vehicle and with all of the necessary parts for vehicle
installation. However, any flexible components may be neutralised with the agreement of the
Type Approval Authority or Technical Service;
3.5.2.2. Hook type couplings intended for use with hinged drawbar trailers - where the imposed
vertical load on the coupling S is zero – shall be tested in the same manner as described in
Paragraph 3.3.2.
3.5.2.3. Hook type couplings intended for use with centre axle trailers (S >0):
3.5.2.3.1. Hook type couplings intended for use with centre axle trailers ≤3.5t shall be tested in the
same way as described in 3.1 of this Annex.
3.5.2.3.2. Hook type couplings intended for use with centre axle trailers above 3.5t shall be tested in the
same way as described in Paragraph 3.3.3.2 of this Annex.
3.5.3. Static Test on Coupling Locking Device
With hook type couplings it is also necessary to test the closure and any locking devices by
means of a static force of 0.6 D acting in the direction of opening. The test shall not cause the
closure to open. The closure/locking device shall be functional after the test.
3.6. Drawbars
3.6.1. Drawbars shall be tested in the same way as drawbar eyes (see Paragraph 3.4.). The Type
Approval Authority or Technical Service may waive an endurance test if the simple design of
a component makes a theoretical assessment of its strength possible. The design forces for
the theoretical verification of the drawbar of centre axle trailers with a mass, C, of up to and
including 3.5t shall be taken from ISO 7641/1:1983. The design forces for the theoretical
verification of drawbars for centre axle trailers having a mass, C, over 3.5t shall be calculated
as follows:
F = (g × S/1,000) + V
Where the force amplitude V is that given in Paragraph 2.11.4. of this Regulation.
The permissible stresses based on the design masses for trailers having a total mass, C, over
3.5t shall be in accordance with Paragraph 5.3. of ISO 7641/1:1983. For bent drawbars
(e.g. swan neck) and for the drawbars of full trailers, the horizontal force component
F = 1.0 × D shall be taken into consideration.

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3.7.2.2. A static lifting test shall be performed on all fifth wheel couplings. Up to a lifting force of
F = g × U there shall not be any major permanent bending of the coupling plate over more
than 0.2% of its width.
In the case of Class G50 standard fifth wheel couplings and comparable couplings for the
same coupling pin diameter, there shall not be any separation of the coupling pin from the
coupling with a lifting force of F = g × 2.5U. In the case of non-standard couplings using a pin
diameter greater than 50mm, for example 90mm pin diameter couplings, the lifting force shall
be: F = g × 1.6U with a minimum value of 500kN.
The force shall be applied by means of a lever bearing on the coupling plate at one end and
being raised at the other end at a distance of 1.0 to 1.5m from the centre of the coupling pin –
see Figure 24.
The lever arm shall be at 90° to the direction of entry of the coupling pin into the coupling. If
the worst case is obvious, this worst case has to be tested. If the worst case is not easy to
determine, the Type Approval Authority or Technical Service shall decide which side to
test. Only one test is necessary.
3.7.3. Dynamic Test
Figure 24
Lifting Test on Fifth Wheel Couplings
The fifth wheel coupling shall be subjected to alternating stress on a test rig (asynchronous
dynamic test) with horizontal alternating and vertical pulsating forces acting simultaneously.
3.7.3.1. In the case of fifth wheel couplings not intended for the positive steering of semi-trailers, the
following forces shall be used:
Horizontal: F = ±0.6 × D
Vertical: F = g × 1.2U
F = g × 0.4U
These two forces shall be applied in the longitudinal median plane of the vehicle with the lines
of action of both forces F and F passing through the centre of the joint of the coupling.
The vertical force F alternates between the limits +g × 1.2U and +g × 0.4U and the horizontal
force between ±0.6D.

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3.10.2. Test Requirements
3.10.2.1. Definition of the Load Intensity Value (LIV):
The LIV is a scalar value which represents the severity of one load time history considering
durability aspects (identical to damage sum). For the damage accumulation the miner
elementary rule is used. For its determination, the load amplitudes and the number of
repetitions of each amplitude are considered (effects of mean loads are not taken into
account).
The S-N curve (Basquin curve) represents the load amplitudes versus the number of
repetitions (S vs. N ). It has a constant slope k in a double logarithmic diagram (i.e. every
amplitude /applied test force S relates to a limited number of cycles N ). The curve
represents the theoretical fatigue limit for the analyzed structure.
The load time history is counted in a range-pair diagram of load amplitude versus number of
repetitions (S vs. n ). The sum of the ratio n /N for all available amplitude levels S is equal
to the LIV.

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To derive a load time history based on above-mentioned LIVs, the slope shall be k = 5
(see definition in Paragraph 3.10.2.1.). The Basquin curve shall pass through the point of an
amplitude S = 0.6 × D with the number of cycles N = 2 × 10 .
The static vertical load S (as defined in Paragraph 2.11.3. of this Regulation) on the coupling
device as declared by the manufacturer shall be added to the vertical loads.
During the test, the maximum amplitudes should not exceed the following values:
longitudinal Fx [-] lateral Fy [-] vertical Fz [-]
Maximum +1.3 × D +0.45 × D +0.6 × D + S
Minimum -1.75 × D -0.45 × D -0.6 × D + S
An example of a load time history which fulfils these requirements is given at:

3.10.3. Test Conditions
The coupling device shall be mounted on a rigid test bench or on a vehicle. In the case of a
3 dimensional time history signal, it shall be applied by three actuators for simultaneous
introduction and control of the force components Fx (longitudinal), Fy (lateral) and
Fz (vertical). In other cases, the number and the position of the actuators may be chosen in
agreement between the manufacturer and the technical services. In any case, the test
installation shall be able to introduce simultaneously the necessary forces in order to fulfil the
LIVs required in Paragraph 3.10.2.2.
All bolts have to be tightened with the torque as specified by the manufacturer.
3.10.3.1. Coupling Device Mounted On Stiff Support:
The compliance of the fixing points of the coupling device shall not exceed 1.5mm from the
reference point of "0-load" during the application of the maximum and minimum forces Fx, Fy,
Fz and each separately applied to the coupling point.
3.10.3.2. Coupling Device Mounted on Vehicle Body or Body Part:
In this case the coupling device shall be mounted on the vehicle body or a body part of the
vehicle type, for which the coupling device is designed. The vehicle or body part shall be fitted
on a suitable rig or test bench in such a manner, that any effect of the vehicles suspension is
eliminated.
The exact conditions during the test shall be declared in the relating test report. Possible
resonance effects have to be compensated by a suitable test facility control system and may
be reduced by additional fixing between vehicle body and test rig or modified frequency.

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ANNEX 7
INSTALLATION AND SPECIAL REQUIREMENTS
1. INSTALLATION AND SPECIAL REQUIREMENTS
1.1. Attachment of Coupling Balls, Hook Couplings and Towing Brackets
1.1.1. Coupling balls, hook coupling and towing brackets shall be attached to vehicles of
Categories M , M (below 3.5t maximum permissible mass) and N in a manner which
conforms to the clearance and height dimensions given in Figure 25. The height shall be
measured at the vehicle loading conditions given in Appendix 1 to this Annex.
The height requirement shall not apply in the case of Category G off-road vehicles as defined
in Annex 7 of the Consolidated Resolution on the Construction of Vehicles (R.E.3).
1.1.1.1. The clearance space shown in Figures 25a and 25b may be occupied by non-demountable
equipment, such as a spare wheel, provided that the distance from the centre of the ball or
the centre of the hook on a vertical plane at the extreme rearmost point of the equipment
does not exceed 250mm. The equipment shall be mounted to allow adequate access for
coupling and uncoupling without risk of injury to the user and without affecting articulation of
the coupling.
1.1.2. For coupling balls or hook coupling and towing brackets the vehicle manufacturer shall supply
mounting instructions and state whether any reinforcement of the fixing area is necessary
(see Annex 2, Appendix 1 of this Regulation).
1.1.3. It shall be possible to couple and uncouple ball couplings/hook coupling when the longitudinal
axis of the ball coupling/hook coupling in relation to the centre line of the coupling ball/hook
coupling and mounting:
is rotated horizontally 60° to right or left, (β = 60°, see Figure 25);
is rotated vertically 10° up or down (α = 10°, see Figure 25);
is rotated axially 10° to right or left.
1.1.4. When the trailer is not coupled to the towing vehicle, the mounted towing bracket and
coupling ball shall not (partly) obscure, within the planes of geometrical visibility, any lighting
component (e.g. rear fog lamp) or the space for mounting and the fixing of the rear
registration plate of the towing vehicle, unless the installed mechanical coupling device can
be removed or repositioned without the use of any tools, except an easily operated (i.e. an
effort not exceeding 20Nm) release key which is carried in the vehicle.
If the installed mechanical coupling device is capable of (partly) obscuring any lighting
component and/or space for mounting and the fixing of the rear registration plate of the towing
vehicle, this shall be duly noted in the test report and clearly stated under 'Remarks' on the
vehicle type approval communication form.
If an alternative location for the space for mounting and the fixing of the rear registration plate
of the towing vehicle and/or any lighting device is specified by the vehicle manufacturer in the
context of a mechanical coupling device (partly) obscuring either one or both, this shall be
duly noted in the test report and clearly stated under 'Remarks' on the vehicle type approval
communication form.

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Figure 25(b)
Clearance Space for Coupling Ball - Plan View

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1.3.3. Easy and Safe Coupling Operation
Drawbar couplings shall be mounted on the vehicle in such a manner that they are easy and
safe to operate.
In addition to the functions of opening (and closing, if applicable) this also includes checking
the position of the indicator for the closed and locked positions of the coupling pin (by sight
and touch).
In the area in which the person operating the coupling has to stand, there shall not be any
points of possible danger such as sharp edges, corners, etc. inherent in the design unless
these are protected so that injury is unlikely.
The way of escape from this area shall not be restricted or barred on either side by any
objects attached to either the coupling or the vehicles.
Any underrun protection device shall not prevent the person adopting a suitable position to
operate the coupling.
1.3.4. Minimum Angle for Coupling Up and Uncoupling
Coupling and uncoupling of the drawbar eye shall be possible when the longitudinal axis of
the drawbar eye in relation to the centre line of the jaw is simultaneously rotated:
50° horizontally to right or left;
6° vertically up or down;
6° axially to right or left.
This requirement shall also apply to Class K hook type couplings for vehicles having
maximum permissible mass above 3.5t.
1.3.5. Accessibility
The distance between the centre of the coupling pin and the edge of the bodywork of the
vehicle shall not exceed 550mm. Where the distance exceeds 420mm, the coupling shall be
fitted with an actuation mechanism which will allow safe operation at a maximum distance of
420mm from the outer board of the bodywork.
The distance of 550mm may be exceeded as follows, provided that technical necessity can
be demonstrated and that easy and safe actuation of the drawbar coupling is not adversely
affected:
(a)
(b)
(c)
To a distance of up to 650mm for vehicles with tipping bodies or rear-mounted
equipment;
To a distance of up to 1,320mm if the unobstructed height is at least 1,150mm;
In the case of car transporters with at least two loading levels when the trailer vehicle is
not separated from the towing vehicle in normal transport operation.

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1.3.8. Acceptability of drawbar couplings with a special joint for vertical rotation – see Annex 5,
Paragraph 3.4.
Couplings having a cylindrical pin and which achieve vertical rotation for the coupled drawbar
eye by means of a special joint will only be permitted when technical necessity can be
demonstrated. This may be the case, for example, on rear tippers when the coupling head
shall be hinged, or with the couplings of heavy transporters when for strength reasons the use
of a cylindrical coupling pin is necessary.
1.4. Attachment of Drawbar Eyes and Drawbars on Trailers
1.4.1. Drawbars for centre axle trailers shall have a support device which is adjustable in height if
the bearing mass at the drawbar eye on the trailer exceeds 50kg, when the trailer is uniformly
loaded to its technically permissible maximum mass.
1.4.2. When attaching drawbar eyes and drawbar to centre-axle trailers with a maximum mass, C, of
more than 3.5t and more than one axle, the trailers shall be equipped with device for axle load
sharing.
1.4.3. Hinged drawbars shall be clear of the ground. They shall not fall below a height of 200mm
from the ground when released from the horizontal position. See also Annex 5,
Paragraphs 5.3. and 5.4.
1.5. Attachment of Fifth Wheel Couplings, Mounting Plates and Coupling Pins on Vehicles
1.5.1. Class G50 fifth wheel couplings shall not be mounted directly on the vehicle frame unless
permitted by the vehicle manufacturer. They shall be fixed to the frame by means of a
mounting plate and the installation instructions provided by the vehicle manufacturer and
coupling manufacturer shall be followed.
1.5.2. Semi-trailers shall be equipped with landing gear or any other equipment which allows
uncoupling and parking of the semi-trailer.
If semi-trailers are equipped so that the connection of the coupling devices, the electrical
systems and braking systems can be effected automatically, the trailer shall have landing
gear which retracts from the ground automatically after the semi-trailer has been coupled up.
These requirements shall not apply in the case of semi-trailers designed for special
operations where they are normally only separated in a workshop or when loading and
unloading in specifically designed operating areas.
1.5.3. The fixing of the fifth wheel coupling pin to the mounting plate on the semi-trailer shall be as
instructed by the vehicle manufacturer or the manufacturer of the fifth wheel coupling pin.
1.5.4. If a semi-trailer is equipped with a steering wedge it shall meet the requirements as described
in Annex 5, Paragraph 7.8.
2. REMOTE INDICATION AND CONTROL
2.1. When installing remote indication and control devices any relevant requirements given in
Annex 5, Paragraph 12 shall be taken into account.

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ANNEX 8
VERIFICATION PROCEDURE FOR VEHICLE WITH
RESPECT TO COUPLING EQUIPMENT INSTALLED
1. GENERAL
The objective of this annex is to provide a procedure and acceptance criterion to verify that the
characteristic performance values of the coupling equipment installed on the vehicle to be
approved are sufficient to sustain the maximum towable mass and other technical
characteristics of the vehicle/combination.
1.1. Verification Procedure and Acceptance Criteria
The performance value requirements shall be calculated using the relevant formulae of
Paragraphs 2 and 3 of this Annex, applying the maximum permissible towing vehicle, trailer
and combination masses which are specified by the vehicle manufacturer in the Annex 2 to this
Regulation.
The acceptance criteria are fulfilled:
(a)
(b)
If the calculated performance value requirements are not higher than the characteristic
performance values of the coupling equipment,
If, in case of a drawbar coupling not fulfilling the above criteria, the calculated
performance value requirements and the limiting V-value specified by the vehicle
manufacturer fulfill all the criteria specified in Paragraph 4 of this Annex.
2. CALCULATION FORMULAE APPLICABLE TO TWO-VEHICLE COMBINATIONS
2.1. Horizontal Forces
�
�
�
For mechanical coupling devices and components not designed to support imposed vertical
loads, the value is:
T �R
D � g kN �
T � R
For mechanical coupling devices and components for centre axle trailers as defined in 2.13, the
value is:
D
T � C
� g kN �
T � C

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L
is the distance from the centre of the drawbar eye to the centre of the axle assembly, in
meters (see Figure 27)
Note: X � 1. 0
L
(If less than 1.0, the value of 1.0 shall be used)
Figure 27
Dimensions of the Centre Axle Trailer
Towable mass: C
3. CALCULATION FORMULAE APPLICABLE TO MULTI-VEHICLE COMBINATIONS
3.1. Combination 1
Description: Rigid truck + Dolly + Semitrailer
Masses [tonnes]:
M = total axle load of rigid truck as coupled
M = total axle load of dolly and semitrailer as coupled
M = total axle load of dolly as coupled
M = total axle load of rigid truck as coupled plus tare weight of dolly
M = support load at king-pin of semitrailer
M = M + total axle load of semitrailer as coupled
Total combination mass = M + M
Towable mass of the rigid truck: M
Towable mass of the dolly: M

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Coupling capability requirement:
Clevis coupling on semitrailer:
D
M �M
X
� 0.65g
V � a M
M � M
L
Fifth wheel:
�
M M � 0.08M
D � 0.5g
M � M � M
�
Note: X � 1. 0 (If less than 1.0, the value of 1.0 shall be used)
L
3.3. Combination 3
Description: Tractor + Semitrailer + Dolly + Semitrailer
Masses [tonnes]:
M = total axle load of tractor as coupled (including support load from first semitrailer)
M = total axle load of tractor and first semitrailer as coupled
M = M + total axle load of second semitrailer as coupled
M = total axle load of dolly as coupled (including support load from second semitrailer)
M = M + tare weight of dolly
M = support load at king-pin of first semitrailer
M = support load at king-pin of second semitrailer
M = M + total axle load of second semitrailer as coupled
M = M + total axle load of first semitrailer as coupled + M
Total combination mass = M + M
Towable mass of the tractor: M
Towable mass of the first semitrailer: M
Towable mass of the dolly: M
Dimensions:
L = distance from drawbar eye to centre of dolly axle group [m]
Coupling capability requirement:
Clevis coupling on first semitrailer:

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T = distance from centre of axle group to coupling point of clevis coupling in rear end of first
centre axle trailer [m]
a = 2.4[m/s ] for semitrailer with steel suspension; 1.8[m/s ] for semitrailer with air suspension
Coupling capability requirement:
Clevis couplings:
D
M
� 0.9g
M
�M
� M
V � V
X
V � a
L
M
V
�
� X
�
�
a
� L
M
�
�
�
�
� T
� �
�
� L
V
�
�
�
�
X X
Note: � 1 � 1 (If less than 1.0, the value of 1.0 shall be used)
L L
3.5. Combination 5
Description: Tractor + Link-trailer + Semitrailer
Masses [tonnes]:
M = total axle load of tractor as coupled (including support load from link-trailer)
M = support load at king-pin of link-trailer
M = M + total axle load of link-trailer and semitrailer as coupled
M = total axle load of link-trailer and semitrailer as coupled
M = support load at king-pin of semitrailer
M = M + total axle load of semitrailer
Total combination mass = M + M
Towable mass of the tractor: M
Towable mass of the linktrailer: M

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