Regulation No. 25-04
|Name:||Regulation No. 25-04|
|Description:||Head Restraints - Whether or not Incorporated in a Seat.|
|Official Title:||Uniform Provisions Concerning the Approval of: Head Restraints (Headrests), Whether or not Incorporated in Vehicle Seats.|
|Country:||ECE - United Nations|
|Date of Issue:||1971-12-30|
|Amendment Level:||04 Series, Supplement 1|
|Number of Pages:||33|
|Vehicle Types:||Bus, Car, Component, Heavy Truck, Light Truck|
|Subject Categories:||Occupant Protection|
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head, restraint, seat, approval, regulation, point, paragraph, position, annex, vehicle, machine, seats, reference, torso, angle, type, line, means, back, restraints, height, case, test, seating, manufacturer, plane, force, amendments, vertical, series, requirements, procedure, device, defined, actual, number, positions, adjustable, distance, measured, front, design, structure, pan, rear, date, leg, mark, approved, load
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June 22, 2015
STATUS OF UNITED NATIONS REGULATION
UNIFORM PROVISIONS CONCERNING THE APPROVAL OF:
HEAD RESTRAINTS (HEADRESTS), WHETHER
OR NOT INCORPORATED IN VEHICLE SEATS
03 series of amendments
Date of Entry into Force: 20.11.89
Corr. 1 of 11.09.92 to the 03 series of amendments
Date of Entry into Force: 11.09.92
Supplement 1 to the 03 series of amendments
Date of Entry into Force: 30.01.94
04 series of amendments
Date of Entry into Force: 15.01.97
Corr. 2 of 15.01.09 to Revision 1 of the Regulation
Date of Entry into Force: 12.11.08
Supplement 1 to the 04 series of amendments
Date of Entry into Force: 15.06.15
REGULATION NO. 25
UNIFORM PROVISIONS CONCERNING THE APPROVAL OF HEAD RESTRAINTS
(HEADRESTS), WHETHER OR NOT INCORPORATED IN VEHICLE SEATS
3. Application for approval
6. General specifications
8. Conformity of production
9. Penalties for non-conformity of production
10. Modification and extension of approval of a type of head restraint
12. Production definitely discontinued
13. Transitional provisions
14. Names and addresses of technical services responsible for conducting approval tests and of
– Communication concerning the approval or refusal or extension or withdrawal of approval
or production definitely discontinued of a type of head restraint, whether or not
incorporated in a seat pursuant to Regulation No. 25
– Arrangements of approval marks
– Procedure for determining the "H" Point and the actual torso angle for seating positions in
– Determination of height and width of head restraint
– Details of lines drawn and measurements taken during tests
– Test procedure for checking energy dissipation
– Determination of dimension "A" of head restraint gaps
2.3. "Type of seat" means a category of seats which do not differ in their dimensions, in their
framework or in their padding, although they may differ in finish and colour;
2.4. "Type of head restraint" means a category of head restraints which do not differ in their
dimensions, in their framework or in their padding, although they may differ in finish, in
colour and in covering;
2.5. "Reference point" of the seat ("H Point") (see Annex 3 to this Regulation) means the trace,
in a vertical plane longitudinal in relation to the seat, of the theoretical axis of rotation
between the leg and the torso of a human body represented by a manikin;
2.6. "Reference line" means a straight line which, either on a test manikin having the weight
and dimensions of a fiftieth percentile adult male or on a test manikin having identical
characteristics, passes through the joint of the leg with the pelvis and the joint of the neck
with the thorax. On the manikin reproduced in Annex 3 to this Regulation, for determining
the H Point of the seat, the reference line is that shown in Figure 1 in the Appendix to that
2.7. "Head line" means a straight line passing through the centre of gravity of the head and
through the joint of the neck with the thorax. When the head is at rest the head line is
situated in the extension of the reference line;
2.8. "Folding seat" means an auxiliary seat intended for occasional use and normally folded;
2.9. "Adjustment system" means the device by which the seat or its parts can be adjusted to a
position suited to the morphology of the seated occupant.
This device may, in particular, permit:
2.9.1. longitudinal displacement,
2.9.2. vertical displacement,
2.9.3. angular displacement;
2.10. "Displacement system" means a device by which the seat or one of its parts can be
displaced or rotated, without a fixed intermediate position, to permit easy access to the
space behind the seat concerned.
3. APPLICATION FOR APPROVAL
3.1. The application for approval shall he submitted by the holder of the trade name or mark of
the seat or the head restraint or by his duly accredited representative.
3.2. It shall be accompanied by the undermentioned documents in triplicate:
3.2.1. a detailed description of the head restraint, specifying in particular the nature of the padding
material or materials and, where applicable, the position and specifications of the braces
and anchorage pieces for the type or types of seats for which approval of the head restraint
4.1.2. provide, at a site shown in the drawings referred to in Paragraphs 22.214.171.124. or 3.2.4. above,
adequate space for the approval mark.
4.2. Where the head restraint is of the "integral" or "removable" type (see definitions in
Paragraphs 2.2.1. and 2.2.2.) the markings referred to in Paragraphs 4.1.1. and 4.1.2.
above may be reproduced on labels situated at a site shown in the drawings referred to in
Paragraph 3.2.4. above.
5.1. If the type of head restraint submitted for approval pursuant to this Regulation meets the
requirements of Paragraph 6. and 7. below, approval of that type of head restraint shall be
5.2. An approval number shall be assigned to each type approved. Its first two digits (at present
03 corresponding to the 03 series of amendments which entered into force on
November 20, 1989) 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 shall not assign this number to another type of head restraint.
5.3. Notice of approval or of extension or of refusal of approval of a type of head restraint
pursuant to this Regulation shall be communicated to the Parties to the 1958 Agreement
applying this Regulation, by means of a form conforming to the model in Annex 1 to this
5.4. There shall be affixed to every head restraint defined in Paragraphs 2.2.1., 2.2.2. and 2.2.3.
approved under this Regulation, whether incorporated in a seat or not, an international
approval mark consisting of:
5.4.1. a circle surrounding the letter "E" followed by the distinguishing number of the country which
has granted approval;
5.4.2. the approval number; and
5.4.3. in the case of a head restraint incorporated in the seat back, in front of the approval number,
the number of this Regulation, the letter "R" and a dash.
5.5. The approval mark shall be affixed in the space referred to in Paragraph 4.1.2. above.
5.6. The approval mark shall be clearly legible and be indelible.
5.7. Annex 2 to this Regulation gives examples of the arrangement of the approval marks.
126.96.36.199. in the case of seats other than the front seats the head restraints may be such that they can
be displaced to a position resulting in a height of less than 750mm, provided that such
position is clearly recognizable to the occupant as not being included for the use of the head
188.8.131.52. in the case of front seats head restraints may be such that they can be automatically
displaced when the seat is not occupied, to a position resulting in a height of less than
750mm, provided that they automatically return to the position of use when the seat is
6.4.4. The dimensions mentioned in Paragraphs 6.4.2. and 184.108.40.206. above may be less than
800mm in the case of front seats and 750mm in the case of other seats to leave adequate
clearance between the head restraint and the interior surface of the roof, the windows or
any part of the vehicle structure; however, the clearance shall not exceed 25mm. In the
case of seats fitted with displacement and/or adjustment systems, this shall apply to all seat
positions. Furthermore, by derogation to Paragraph 220.127.116.11. above, there shall not be any
"use position" resulting in a height lower than 700mm.
6.4.5. By derogation to the height requirements mentioned in Paragraphs 6.4.2. and 18.104.22.168.
above, the height of any head restraint designed to be provided in rear centre seats or
seating positions shall be not less than 700mm.
6.5. The height of the device on which the head rests, measured as prescribed in
Paragraph 7.2., shall in the case of a head restraint adjustable for height be not less than
6.6. There shall be no gap of more than 60mm between the seat back and the head restraint in
the case of a device not adjustable for height.
6.6.1. If the head restraint is adjustable for height it shall, in its lowest position, be not more than
25mm from the top of the seat back.
6.6.2. In the case of a head restraint not adjustable for height, the area to be considered is:
22.214.171.124. above a plane perpendicular to the reference line at 540mm from the R Point and
126.96.36.199. between two vertical longitudinal planes passing at 85mm on either side of the reference
In this area, one or more gaps, which regardless of its shape can show a distance 'a'
measured as described in Paragraph 7.5. of more than 60mm, are permitted provided that
after the additional test under Paragraph 188.8.131.52., the requirements of Paragraph 184.108.40.206.
are still met.
6.6.3. In the case of head restraints adjustable for height, one or more gaps, which regardless of
its shape can show a distance "a" measured as described in Paragraph 7.5. of more than
60mm, are permitted on the part of the device serving as the head restraint provided that,
after the additional test under Paragraph 220.127.116.11., the requirements of Paragraph 18.104.22.168.
are still met.
7.3.2. The width of the head restraint to be taken into consideration in implementing the
requirement of Paragraph 6.7. is the distance L separating the traces of planes P and P' in
plane S .
7.3.3. The width of the head restraint shall if necessary also be determined 635mm above the
reference point of the seat, this distance being measured along the reference line.
7.4. Determination of the Effectiveness of the Device
7.4.1. The effectiveness of the head restraint shall be checked by the static test described below.
7.4.2. Preparation for the test
22.214.171.124. If the head restraint is adjustable it shall be set in the highest position.
126.96.36.199. In the case of a bench seat, where part or all of the supporting frame (including that of the
head restraints) is common to more than one seating position, the test shall be conducted
simultaneously for all those seating positions.
188.8.131.52. If the seat or the seat-back is adjustable relative to a head restraint anchored to the vehicle
structure, it shall be placed in the most unfavourable position as considered by the technical
184.108.40.206. All lines shall be drawn in the vertical plane of symmetry of the seat considered (see
Annex 5 to this Regulation).
220.127.116.11 A projection of the reference line R shall be drawn in the plane referred to in
18.104.22.168 The displaced reference line R shall be determined by applying to the part simulating the
back in the manikin referred to in Annex 3 to this Regulation an initial force producing a
rearward moment of 37,3 daNm about the "H" Point.
22.214.171.124 By means of a spherical head 165mm in diameter an initial force producing a moment of
37,3 daNm about the "H" Point shall be applied at right angles to the displaced reference
line R at a distance of 65mm below the top of the head restraint the reference line being
retained in its displaced position R as determined in accordance with the requirements of
Paragraph 126.96.36.199. above.
188.8.131.52.1 If the presence of gaps prevents the application of the force prescribed above at 65mm from
the top of the head restraint, the distance may be reduced so that the axis of the force
passes through the centre line of the frame element nearest to the gap.
184.108.40.206.2 In the case described in Paragraphs 6.6.2. and 6.6.3. above, the test shall be repeated by
applying to each gap, using a sphere of 165mm in diameter, a force:
passing through the centre of gravity of the smallest of the sections of the gap, along
transversal planes parallel to the reference line, and reproducing a moment of 37.3 daNm
about the "R" Point.
10. MODIFICATION AND EXTENSION OF APPROVAL OF A TYPE OF HEAD RESTRAINT
10.1. Every modification of the type of head restraint shall be notified to the administrative
department which approved the type of head restraint. The department may then either:
10.1.1. Consider that the modifications made are unlikely to have an appreciable adverse effect and
that in any case the head restraint still complies with the requirements; or
10.1.2. Require a further test report from the technical service responsible for conducting the tests.
10.2. Confirmation or refusal of approval, specifying the alterations shall be communicated by the
procedure specified in Paragraph 5.3. above to the Parties to the Agreement applying this
10.3. The competent authority issuing the extension of approval shall assign a series number for
such an extension and inform thereof the other Parties to the 1958 Agreement applying this
Regulation by means of a communication form conforming to the model in Annex 1 to this
The manufacturer shall supply, with each model conforming to a type of head restraint
approved, particulars of the types and characteristics of the seats for which the head
restraint is approved. When the head restraint is adjustable, the adjusting and/or release
operations must be clearly stated in this notice.
12. PRODUCTION DEFINITELY DISCONTINUED
If the holder of the approval completely ceases to manufacture a head restraint approved in
accordance with this Regulation, he shall so inform the authority which granted the
approval. Upon receiving the relevant communication that authority shall inform thereof the
other Parties to the 1958 Agreement applying this Regulation by means of a communication
form conforming to the model in Annex 1 to this Regulation.
13. TRANSITIONAL PROVISIONS
13.1. As from the official date of entry into force of the 04 series of amendments, no Contracting
Party applying this Regulation shall refuse to grant ECE approvals under this Regulation as
amended by the 04 series of amendments.
13.2. As from 24 months after the date of entry into force of the 04 series of amendments,
Contracting Parties applying this Regulation shall grant ECE approval only if the vehicle
type to be approved complies with the requirements of this Regulation as amended by the
04 series of amendments.
13.3. As from 48 months after the date of entry into force of the 04 series of amendments, existing
approvals to this Regulation shall cease to be valid, except in the case of vehicle types
which comply with the requirements of this Regulation as amended by the 04 series of
(maximum format: A4 (210 x 297mm))
Name of administration:
PRODUCTION DEFINITELY DISCONTINUED
of a type of head restraint, whether or not incorporated in a seat pursuant to Regulation No. 25
Approval No. .................................................. Extension No. ................................
1. Trade name or mark...................................................................................................................
2. Manufacturer's name .................................................................................................................
3. If applicable, name of manufacturer's representative ................................................................
4. Address ......................................................................................................................................
5. Submitted for approval on ..........................................................................................................
6. Technical service conducting tests ............................................................................................
7. Brief description of the head restraint .....................................................................................
8. Type and characteristics of the seats for which the head restraint is intended or in which it is
9. Types of vehicles for which the seats for which the head restraint is designed are intended
ARRANGEMENTS OF APPROVAL MARKS
1. Approval mark for an "integrated" or "removable" type head restraint (see the definitions in
Paragraphs 2.2.1. and 2.2.2. of this Regulation).
a = 8mm min.
The above approval mark affixed to one or more "integrated" or "removable" type head
restraints shows that, pursuant to Regulation No. 25, the type of head restraint has been
approved in the Netherlands (E4) under approval number 032439. The first two digits of the
approval number indicate that the approval was granted in accordance with the
requirements of Regulation No. 25 as amended by the 03 series of amendments.
2. Approval mark for a "separate" type head restraint (see the definition in Paragraph 2.2.3. of
a = 8mm min
The above approval mark affixed to a head restraint shows that the head restraint in
question has been approved and that it is a "separate" head restraint, approved in the
Netherlands (E4), under approval number 032439. The first two digits of the approval
number indicate that the approval was granted in accordance with the requirements of
Regulation No. 25, as amended by the 03 series of amendments.
2.7. "Design torso angle" means the angle measured between a vertical line through the
"R" Point and the torso line in a position which corresponds to the design position of the
seat-back established by the vehicle manufacturer;
2.8. "Centreplane of occupant" (C/LO) means the median plane of the 3 DH machine
positioned in each designated seating position; it is represented by the co-ordinate of the
"H" Point on the "Y" axis. For individual seats, the centreplane of the seat coincides with the
centreplane of the occupant. For other seats, the centreplane of the occupant is specified by
2.9. "Three dimensional reference system" means a system as described in Appendix 2 to
2.10. "Fiducial marks" are physical points (holes, surfaces, marks or indentations) on the vehicle
body as defined by the manufacturer;
2.11. "Vehicle measuring attitude" means the position of the vehicle as defined by the
co-ordinates of fiducial marks in the three-dimensional reference system.
3.1. Data Presentation
For each seating position where reference data are required in order to demonstrate
compliance with the provisions of the present Regulation, all or an appropriate selection of
the following data shall be presented in the form indicated in Appendix 3 to this Annex:
3.1.1. the co-ordinates of the "R" Point relative to the three-dimensional reference system;
3.1.2. the design torso angle;
3.1.3. all indications necessary to adjust the seat (if it is adjustable) to the measuring position set
out in Paragraph 4.3. below.
3.2. Relationship between Measured Data and Design Specifications
3.2.1. The co-ordinates of the "H" Point and the value of the actual torso angle obtained by the
procedure set out in Paragraph 4 below shall be compared, respectively, with the
co-ordinates of the "R" Point and the value of the design torso angle indicated by the vehicle
3.2.2. The relative positions of the "R" Point and the "H" Point and the relationship between the
design torso angle and the actual torso angle shall be considered satisfactory for the seating
position in question if the "H" Point, as defined by its co-ordinates, lies within a square of
50mm side length with horizontal and vertical sides whose diagonals intersect at the
"R" Point, and if the actual torso angle is within 5° of the design torso angle.
3.2.3. If these conditions are met, the "R" Point and the design torso angle, shall be used to
demonstrate compliance with the provisions of this Regulation.
4.7. Adjust the feet and leg positions of the 3 DH machine as follows:
4.7.1. Designated seating position: driver and outside front passenger.
220.127.116.11. Both feet and leg assemblies shall be moved forward in such a way that the feet take up
natural positions on the floor, between the operating pedals if necessary. Where possible
the left foot shall be located approximately the same distance to the left of the centreplane
of the 3 DH machine as the right foot is to the right. The spirit level verifying the transverse
orientation of the 3 DH machine is brought to the horizontal by readjustment of the seat pan
if necessary, or by adjusting the leg and foot assemblies towards the rear. The line passing
through the "H" Point sight buttons shall be maintained perpendicular to the longitudinal
centreplane of the seat.
18.104.22.168. If the left leg cannot be kept parallel to the right leg and the left foot cannot be supported by
the structure, move the left foot until it is supported. The alignment of the sight buttons shall
4.7.2. Designated seating position: outboard rear
For rear seats or auxiliary seats, the legs are located as specified by the manufacturer. If the
feet then rest on parts of the floor which are at different levels, the foot which first comes
into contact with the front seat shall serve as a reference and the other foot shall be so
arranged that the spirit level giving the transverse orientation of the seat of the device
indicates the horizontal.
4.7.3. Other designated seating positions:
The general procedure indicated in Paragraph 4.7.1. above shall be followed except that the
feet shall be placed as specified by the vehicle manufacturer.
4.8. Apply lower leg and thigh weights and level the 3 DH machine.
4.9. Tilt the back pan forward against the forward stop and draw the 3 DH machine away from
the seat-back using the T-bar. Reposition the 3 DH machine on the seat by one of the
4.9.1. If the 3 DH machine tends to slide rearward, use the following procedure. Allow the 3 DH
machine to slide rearward until a forward horizontal restraining load on the T-bar is no
longer required i.e. until the seat pan contacts the seat-back. If necessary, reposition the
4.9.2. If the 3 DH machine does not tend to slide rearward, use the following procedure. Slide the
3 DH machine rearwards by applying a horizontal rearward load to the T-bar until the seat
pan contacts the seat-back (see Figure 2 of Appendix 1 to this Annex).
4.10. Apply a 100 ± 10N load to the back and pan assembly of the 3 DH machine at the
intersection of the hip angle quadrant and the T-bar housing. The direction of load
application shall be maintained along a line passing by the above intersection to a point just
above the thigh bar housing (see Figure 2 of Appendix 1 to this Annex). Then carefully
return the back pan to the seat-back. Care must be exercised throughout the remainder of
the procedure to prevent the 3 DH machine from sliding forward.
4.11. Install the right and left buttock weights and then, alternately, the eight torso weights.
Maintain the 3 DH machine level.
4.16. If the seats in the same row can be regarded as similar (bench seat, identical seats, etc.)
only one "H" Point and one "actual torso angle" shall be determined for each row of seats,
the 3 DH machine described in Appendix 1 to this Annex being seated in a place regarded
as representative for the row. This place shall be:
4.16.1. in the case of the front row, the driver's seat;
4.16.2. in the case of the rear row or rows, an outer seat.
ANNEX 3 – APPENDIX 1
3 DH Machine Elements Designation
ANNEX 3 – APPENDIX 2
THREE-DIMENSIONAL REFERENCE SYSTEM
1. The three-dimensional reference system is defined by three orthogonal planes established
by the vehicle manufacturer (see Figure).
2. The vehicle measuring attitude is established by positioning the vehicle on the supporting
surface such that the co-ordinates of the fiducial marks correspond to the values indicated
by the manufacturer.
3. The co-ordinates of the "R" Point and the "H" Point are established in relation to the fiducial
marks defined by the vehicle manufacturer.
Three-Dimensional Reference System
DETERMINATION OF THE HEIGHT AND WIDTH OF HEAD RESTRAINTS
TEST PROCEDURE FOR CHECKING ENERGY DISSIPATION
1. INSTALLATION, TEST APPARATUS, RECORDING INSTRUMENTS AND PROCEDURE
The head restraint covered with an energy dissipating material shall be fitted and tested on
the seat or the structural part of the vehicle in which it is installed. The structural component
shall be firmly secured to the test bench so as to remain stationary when the impact is
applied, and the base on which it rests shall, in the absence of a particular specification for
which reasons are given, be approximately horizontal. The seat back, if it can be adjusted,
shall be bolted into the position described in Paragraph 7.2.2. of this Regulation.
The head restraint shall be mounted on the seat back, as it is presented in the vehicle. In
the case of a separate head restraint, it shall be secured to the part of the vehicle structure
to which it is normally secured.
If the head restraint is adjustable it shall be placed in the most unfavourable position the
adjustment device permits.
1.2. Test Apparatus
1.2.1. This apparatus consists of a pendulum whose pivot is supported by ball-bearings and
whose reduced mass at its centre of percussion is 6.8kg. The lower extremity of the
pendulum consists of a rigid headform 165mm in diameter whose centre is identical with the
centre of percussion of the pendulum.
1.2.2. The headform shall be fitted with two accelerometers and a speed measuring device, all
capable of measuring values in the direction of impact.
1.3. Recording instruments
The recording instruments used shall be such that measurements can be made with the
following degrees of accuracy:
accuracy = ± 5% of the actual value;
frequency class of the measurement chain: CFC 600 corresponding to the characteristics of
ISO standard 6487-1987;
Transverse sensitivity ≤ 5% of the lowest point on the scale.
DETERMINATION OF DIMENSION "A" OF HEAD RESTRAINT GAPS
(see paragraphs 6.6.2 and 6.6.3 of this Regulation)
Example of Horizontal Gaps
Note: Section A – A is to be made in a point of the gap area which allows the maximum sphere intrusion,
without exerting any load.
Example of Vertical Gaps
Note: Section A – A is to be made in a point of the gap area which allows the maximum sphere intrusion,
without exerting any load.