ISO 16840-4:2009

INTERNATIONAL ISO
STANDARD 16840-4
First edition
2009-03-15


Wheelchair seating —
Part 4:
Seating systems for use in motor
vehicles
Sièges de fauteuils roulants —
Partie 4: Systèmes d'assise dans les véhicules à moteurs





Reference number
ISO 16840-4:2009(E)
©
ISO 2009

---------------------- Page: 1 ----------------------
ISO 16840-4:2009(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.


COPYRIGHT PROTECTED DOCUMENT


©  ISO 2009
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland

ii © ISO 2009 – All rights reserved

---------------------- Page: 2 ----------------------
ISO 16840-4:2009(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 2
4 Design requirements . 6
4.1 Reduction of sharp edges. 6
4.2 Accommodation of vehicle-anchored occupant restraints. 6
5 Performance requirements . 7
5.1 Frontal impact test. 7
5.2 Accommodation of vehicle-anchored occupant belt restraints . 8
6 Identification, labelling, user instructions, warning and disclosure requirements . 8
6.1 Identification and labelling . 8
6.2 Pre-sale literature. 9
6.3 User instructions . 9
6.4 User warnings . 9
7 Documentation of compliance . 10
7.1 General. 10
7.2 Test report . 10
7.3 Frontal impact test. 11
7.4 Design, labelling and literature requirements . 11
Annex A (normative) Test method for frontal impact test . 12
Annex B (normative) Specifications for the surrogate wheelchair base used for impact testing of
a seating system. 19
Annex C (informative) Wheelchair seating system — Static test method. 24
Annex D (normative) Test method for rating the seating system's accommodation of vehicle-
anchored belt restraints. 33
Annex E (informative) Recommended user instructions and user warnings . 37
Bibliography . 40

© ISO 2009 – All rights reserved iii

---------------------- Page: 3 ----------------------
ISO 16840-4:2009(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 16840-4 was prepared by Technical Committee ISO/TC 173, Assistive products for persons with disability,
Subcommittee SC 1, Wheelchairs.
ISO 16840 consists of the following parts, under the general title Wheelchair seating:
⎯ Part 1: Vocabulary, reference axis convention and measures for body segments, posture and postural
support surfaces
⎯ Part 2: Determination of physical and mechanical characteristics of devices intended to manage tissue
integrity — Seat cushions
⎯ Part 3: Determination of static, impact and repetitive load strengths for postural support devices
⎯ Part 4: Seating systems for use in motor vehicles
iv © ISO 2009 – All rights reserved

---------------------- Page: 4 ----------------------
ISO 16840-4:2009(E)
Introduction
Transportation safety research has demonstrated that the design of the vehicle seat, the occupant restraints
and seat compartment in motor vehicles play a vital role in protecting the occupant in the event of a crash. For
some wheelchair users, it is not feasible to transfer to the seat provided by the vehicle manufacturer and they
must remain seated in their wheelchair while travelling in a vehicle. ISO 7176-19 provides a means of
evaluating the design and frontal crashworthiness performance of complete wheelchairs when used as
forward-facing seats in motor vehicles. However, it is common practice that a seating system from one
manufacturer and a wheelchair base from another manufacturer be used to form the complete wheelchair.
Wheelchair seating systems may also be intended for use on multiple models of wheelchair bases. For this
reason, there is a need to be able to evaluate the design and performance of wheelchair seating systems
independent of the commercial wheelchair bases on which they may be installed. This part of ISO 16840
provides a means of assessing frontal impact crashworthiness of seating systems without the host wheelchair
by using a surrogate wheelchair base.
Manufacturers may choose to not test customized variations of a given seating system. The manufacturer
may test a representative variation of the seating system and it is for the manufacturer to document how the
results of this test would apply to the limitations in use and instructions for use supplied with the product.
This part of ISO 16840 is intended to encourage safer motor vehicle transportation of wheelchair users by
increasing the availability of wheelchair seating systems that comply with basic principles of occupant
protection. This part of ISO 16840 should not be used to deny or limit wheelchair user access to motor vehicle
transportation.
Currently this part of ISO 16840 addresses only complete wheelchair seating systems and the test
requirements are representative of frontal impact conditions. However, future versions may address testing of
the individual components of the seating system as well as other directions of impact such as side or rear.

© ISO 2009 – All rights reserved v

---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 16840-4:2009(E)

Wheelchair seating —
Part 4:
Seating systems for use in motor vehicles
1 Scope
This part of ISO 16840 specifies test methods and requirements for design and performance, for instructions
and warnings and for product marking and labelling of seating systems intended to be used as a
forward-facing seat in a motor vehicle when fitted to a manual or powered wheelchair. It evaluates the frontal
crashworthiness performance of complete seating systems for occupancy by adults or children of mass equal
to or greater than 22 kg.
This part of ISO 16840 only applies to complete wheelchair seating systems including attachment hardware,
designed to be used with a wheelchair base tested as part of a wheelchair system that conforms to
ISO 7176-19 performance requirements and that has securement points for use with four-point, strap-type
tiedowns.
This part of ISO 16840 applies to seating systems designed to be used with occupant restraints that anchor
either to the vehicle, the tiedown system, the seating system or the wheelchair base.
Seating systems that are intended only for use with a specific wheelchair base should be tested to
ISO 7176-19 using the specifically intended wheelchair base.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 898-7, Mechanical properties of fasteners — Part 7: Torsional test and minimum torques for bolts and
screws with nominal diameters 1 mm to 10 mm
ISO 6487, Road vehicles — Measurement techniques in impact tests — Instrumentation
ISO 7176-19:2008, Wheelchairs — Part 19: Wheeled mobility devices for use as seats in motor vehicles
ISO 10542-1:2001, Technical systems and aids for disabled or handicapped persons — Wheelchair tiedown
and occupant-restraint systems — Part 1: Requirements and test methods for all systems
ISO 10542-2, Technical systems and aids for disabled or handicapped persons — Wheelchair tiedown and
occupant-restraint systems — Part 2: Four-point strap-type tiedown systems
FMVSS 201, Standard No. 201, Occupant protection in interior impact. (Federal Motor Vehicle Safety
Standards), 49 CFR 571.201
ECE Regulation 21, Uniform provisions concerning the approval of vehicles with regard to their interior fittings,
Revision 2, Amendment 2
ASTM E527-83 (2003), Standard Practice for Numbering Metals and Alloys (UNS)
© ISO 2009 – All rights reserved 1

---------------------- Page: 6 ----------------------
ISO 16840-4:2009(E)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
adult
person having a mass equal to or greater than 43 kg
3.2
anchor point
location on a vehicle interior component, floor, wall, wheelchair, or wheelchair tiedown, to which an
anchorage (3.3) is attached
3.3
anchorage
assembly of components and fittings by which loads are transferred directly from the wheelchair tiedown to
the vehicle, or from the occupant restraint to the vehicle, wheelchair, wheelchair tiedown or vehicle interior
component
3.4
anthropomorphic test device
ATD
articulated physical analogue used to represent a wheelchair occupant in a test
3.5
attachment hardware
mechanical means of attaching a seating system to the wheelchair frame
EXAMPLE Metal or plastic hooks, nuts or bolts.
3.6
back support angle
angle of the back support reference plane with reference to a vertical plane
NOTE Measurement method specified in ISO 7176-7.
3.7
back support surface
component of seating system intended to support the posterior surface of the sacral, lumbar and/or thoracic
segments of the trunk
3.8
back support reference plane
plane associated with the back support of the wheelchair, which is referenced to make measurements
NOTE Method for determining the location of this reference plane specified in ISO 7176-7.
3.9
belt
length of webbing material used as part of an occupant restraint or postural support
3.10
child
person having a mass equal to or greater than 22 kg and less than 43 kg
3.11
custom contoured
uniquely shaped to match the wheelchair occupant
2 © ISO 2009 – All rights reserved

---------------------- Page: 7 ----------------------
ISO 16840-4:2009(E)
3.12
excursion
horizontal movement of an ATD (3.4) or wheelchair during a test relative to its initial position on an impact sled
3.13
forward facing
orientation in which the wheelchair-seated occupant faces the front of the vehicle, with the reference plane
within ten degrees of the longitudinal axis of the vehicle
3.14
four-point tiedown
wheelchair tiedown that attaches to the wheelchair frame at four separate securement points and also
attaches to the vehicle at four separate anchor points
3.15
four-point strap-type tiedown
four-point tiedown (3.14) that uses four strap assemblies to secure the wheelchair in the vehicle
3.16
H-point
point located on the left and right side of the pelvic region of an ATD (3.4) that represents the approximate
location of the human hip joint centre in the side view, as specified by the ATD manufacturer
3.17
head support
postural aid to support the head of a wheelchair occupant, not designed or intended to provide head restraint
in a vehicle impact
3.18
head restraint
device intended to limit rearward excursion of the wheelchair occupant’s head in a vehicle impact
3.19
impact simulator
device for applying a programme of acceleration and deceleration modes to a section of a vehicle or simulated
vehicle structures, including instrumentation for measuring data required by this part of ISO 16840
3.20
impact sled
part of an impact simulator (3.19) on which components can be mounted for impact testing
3.21
occupant restraint
system or device intended to restrain a motor vehicle occupant during impact in order to prevent ejection, and
prevent or minimize contact with the vehicle interior components and other occupants
3.22
pelvic-belt restraint
lap-belt restraint
portion of the occupant restraint intended to limit movement of the pelvis by application of restraint forces to
the pelvis
See Figure 1.
© ISO 2009 – All rights reserved 3

---------------------- Page: 8 ----------------------
ISO 16840-4:2009(E)

Key
1 shoulder-belt restraint
2 pelvic-belt restraint
Figure 1 — Three-point-belt restaint comprised of a pelvic-belt restraint and a shoulder-belt restraint
that connect together near the hip of the occupant
3.23
point P
side-view projection of a point on the seating system which lies at the cross-sectional centre of a 100 mm
diameter, 200 mm long, cylinder with a maximum weight of 0,5 kg positioned with the longitudinal axis
perpendicular to the wheelchair reference plane, such that the curved surface of the cylinder is in contact with
the seat and back support surfaces
See Figure 2.
Dimensions in millimetres

Key
1 cylinder, diameter 100 mm
2 point P
a
Wheelchair reference plane.
b
Wheelchair ground plane.
Figure 2 — Seating system reference point P and wheelchair reference and ground planes
4 © ISO 2009 – All rights reserved

---------------------- Page: 9 ----------------------
ISO 16840-4:2009(E)
3.24
postural support device
component and/or belt used to support a person in a desired seated position during normal wheelchair use
NOTE Postural support devices are not designed or intended to provide occupant restraint on vehicle impact.
3.25
seat plane angle
angle of seat reference plane (3.27) with reference to a horizontal plane
NOTE Measurement method specified in ISO 7176-7.
3.26
seat support surface
component of seating system intended to support the inferior surface of the buttocks and thighs
3.27
seat reference plane
plane associated with the seat of the wheelchair, which is referenced to make measurements
NOTE Methods for determining the location of this reference plane are specified in ISO 7176-7.
3.28
seating system
seat and back support surfaces and their attachment hardware
3.29
securement points
points on the wheelchair to which wheelchair tiedowns are connected
3.30
shoulder-belt restraint
upper torso restraint
portion of the occupant restraint intended to limit movement of the upper body by application of restraining
forces to either or both clavicles
See Figure 1.
3.31
strap
length of webbing material used in a wheelchair tiedown
3.32
support surface
part of the seating system that is intended to contact the wheelchair occupant
3.33
surrogate wheelchair base
SWCB
re-usable device that conforms to the requirements of Annex B, used to simulate a wheelchair base for the
purpose of testing seating systems
© ISO 2009 – All rights reserved 5

---------------------- Page: 10 ----------------------
ISO 16840-4:2009(E)
3.34
three-point-belt restraint
three-point restraint
occupant restraint assembly with three anchorages comprised of both a pelvic-belt restraint and a diagonal
shoulder-belt restraint that connect together near the hip of the occupant.
See Figure 1.
3.35
wheelchair base
portion of the wheelchair consisting of the wheels and wheelchair frame (3.36)
3.36
wheelchair frame
portion of the wheelchair consisting of the members that make up the supporting structure
3.37
wheelchair ground plane
plane representing the surface on which the wheelchair rests
See Figure 2.
3.38
wheelchair reference plane
vertical plane in longitudinal centreline of the wheelchair
See Figure 2.
3.39
wheelchair tiedown
wheelchair securement system
device or system designed to secure a forward-facing wheelchair in place in a motor vehicle
3.40
wheelchair tiedown and occupant restraint system
WTORS
complete restraint system for wheelchair-seated occupants comprised of equipment for wheelchair tiedown
and a belt-type occupant restraint
4 Design requirements
NOTE It can be beneficial for some users to have a head restraint as a part of their seating system.
4.1 Reduction of sharp edges
Webbing shall be protected from contacting sharp corners and edges. If the edge of a rigid component of a
seating system has a radius less than 2,0 mm, it shall be covered with padding capable of absorbing energy
to reduce the likelihood of injuries to wheelchair users and other vehicle occupants during a vehicle impact.
Energy-absorbing padding should conform to the requirements of FMVSS 201 and/or ECE Regulation No. 21.
4.2 Accommodation of vehicle-anchored occupant restraints
The seating system shall be constructed in such a way that any part of the system (e.g. frame, hip or thigh
supports, etc) will not hold a lap-belt or shoulder-belt restraint away from a seated user’s pelvis or upper torso.
6 © ISO 2009 – All rights reserved

---------------------- Page: 11 ----------------------
ISO 16840-4:2009(E)
5 Performance requirements
NOTE Informative Annex C provides manufacturers with a preliminary means to evaluate the performance of their
seating system using low cost static tests. It is important to note that static testing results may not be equivalent to
dynamic test performance.
5.1 Frontal impact test
5.1.1 General
The wheelchair seating system shall be tested in accordance with Annex A using the surrogate wheelchair
base, as specified in Annex B, secured by a four-point strap-type tiedown that complies with ISO 10542-1 and
ISO 10542-2. The requirements of 5.1.2 and 5.1.3 shall be met during and after the conducted test.
5.1.2 During the frontal impact test
When tested in accordance with Annex A, the following requirements shall be met during the test.
a) The horizontal excursions of the ATD and the seating system shall not exceed the values given in Table 1.
NOTE Excursion limits are based upon prevention of occupant secondary impact with vehicle interior.
b) Except when the test has been conducted using a wheelchair base or seat-anchored pelvic-belt restraint
or a completely wheelchair base or seat-anchored occupant restraint system, the knee excursion, X ,
knee
shall exceed the point P excursion, X , as follows.
ss
X /X W 1,1
knee ss
Refer to Table 1 for definitions of X and X .
knee ss
NOTE Conformity with this requirement reduces the potential for the seating system to apply loads to the wheelchair
occupant.
c) The seating system shall not separate from the surrogate wheelchair base at any attachment point.
5.1.3 After the frontal impact test
When tested in accordance with Annex A, the following requirements shall be met at the end of the test.
a) The ATD shall be retained in the seating system in a seated posture, as determined by the ATD torso
being oriented at not more than 45° to the vertical when viewed from any direction.
NOTE The angle of the ATD torso can be estimated by aligning the edge of an inclinometer with a line drawn
connecting the centre of the ATD's shoulder and the ATD's hip.
b) The load-carrying components of seating system and attachment hardware shall not show visible
fractures or deformation that prevent it from supporting the mass of the ATD.
c) Components, fragments or accessories of the seating system with a mass greater than 0,1 kg shall not
have completely separated from the seating system.
d) Rigid seating system components that may contact the occupant shall not fragment or separate in a
manner that produces sharp edges with a radius of less than 2,0 mm.
e) The post-test height of the average of left and right ATD H-points relative to the wheelchair ground plane
shall not change by more than 20 % from the pre-test height.
© ISO 2009 – All rights reserved 7

---------------------- Page: 12 ----------------------
ISO 16840-4:2009(E)
Table 1 — Horizontal excursion limits
Dimensions in millimetres
Excursion 6-year old child 10-year old Small adult Midsize and
Measurement point
variable ATD child ATD female ATD large adult ATD
Point P of seating system X 150 175 200 200
ss
ATD knee centre X 300 325 375 375
knee
ATD front of head X 450 500 550 650
headF
ATD back of head X −350 −400 −400 −450
headR
X is the forward horizontal distance relative to the sled platform between the point P target on the seating system
ss
at time t , to the point P target at the time of peak seating system excursion.
0
X is the horizontal distance relative to the sled platform between the ATD knee joint target at time t , to the
knee 0
knee-joint target at the time of peak knee excursion.
X is the horizontal distance relative to the sled platform between the most forward point on the ATD's head above
headF
the nose at time t , to the most forward point on the ATD's head at the time of peak head excursion.
0
X is the horizontal distance relative to the sled platform between the most rearward point on the ATD's head at
headR
time t , to the most rearward point on the ATD's head at the time of peak head excursion.
0
NOTE 1 Refer to Table A.1 for appropriate ATD selection.
NOTE 2 Positive limit values indicate forward excursions, while negative values indicate rearward excursions.
5.2 Accommodation of vehicle-anchored occupant belt restraints
The wheelchair seating system shall be tested for accommodation of vehicle-anchored occupant restraint
systems in accordance with Annex D and the resulting rating shall be reported in the product presale literature.
6 Identification, labelling, user instructions, warning and disclosure requirements
6.1 Identification and labelling
The wheelchair seating system shall be permanently marked with:
a) the manufacturer’s name;
b) the month and year of manufacture;
c) a unique serial number;
d) a statement that the seating system meets the requirements of ISO 16840-4:2008;
e) a statement that any postural support device not intended for use as occupant restraint in motor vehicle
transport may not provide occupant protection in a vehicle impact;
f) the maximum occupant mass;
g) an indication that each component of the system that functions as a postural support conforms to
requirements of ISO 16840-4:2008.
8 © ISO 2009 – All rights reserved

---------------------- Page: 13 ----------------------
ISO 16840-4:2009(E)
6.2 Pre-sale literature
The seating system manufacturer's presale literature shall include:
a) a statement that the seating system is intended only for use with wheelchair bases tested as part of a
complete wheelchair system that conforms to the performance requirements of ISO 7176-19;
b) a statement that the seating system must be used on a wheelchair base that provides securement points
that conform to the design requirements of ISO 7176-19;
c) a description of the seating system including the components that are intended for use during motor
vehicle transport;
d) a statement that the seating system is designed to be forward facing when used with a wheelchair base in
a motor vehicle;
e) a description of the WTORS to be used;
1)
f) the overall score and rating of the seating system (i.e. A, B or C) with regard to accommodating vehicle-
anchored occupant restraints, and an explanation of the different ratings based on the test methods of
Annex D.
6.3 User instructions
User instructions shall be provided with each seating system in the official languages of the countries in which
the product is marketed, and shall include:
a) a statement that the seating system meets the requirements of ISO 16840-4:2008 and that it is suitable
for use as a motor vehicle seat when used with an appropriate wheelchair base;
b) a statement describing assembly, use, maintenance and any limitations in using the seating system with
a wheelchair base in a motor vehicle;
c) in cases of custom-contoured seating systems, a statement that custom contoured seating systems may
require a qualified professional to configure and install the seating system;
d) a statement that both a pelvic-belt restraint and shoulder-belt restraint should be used.
6.4 User warnings
The seating manufacturer shall provide the following warnings in the user instructions using 12-point or larger
bold font:
a) the seating system shall only be used with wheelchair bases that were tested as part of a wheelchair
system that conforms to ISO 7176-19 performance requirements and that has securement points for use
with four-point, strap-type tiedowns;
b) the seating system shall only be used for forward-facing seating in motor vehicles;
c) the seating system shall only be used as indicated in the manufacturer's instructions;
d) wheelchair-mounted trays not specifically intended to be used in transport shall:
1) be removed and secured separately in the vehicle or
2) be secured to the wheelchair but positioned away from the wheelchair-seated occupant with energy-
absorbing padding placed between the tray and the occupant;

1) A = good; B = acceptable; C = poor.
© ISO 2009 – All rights reserved 9

---------------------- Page: 14 ----------------------
ISO 16840-4:2009(E)
e) postural support devices that are not labelled as conforming to ISO 16840-4 may be used when in a
vehicle, but should not be relied on for occupant restraint;
f) alterations or substitutions shall not be made to the seating system structure,
...