ISO 16333:2004

Heavy commercial vehicles and buses — Steady-state rollover threshold — Tilt-table test method

ISO 16333:2004 specifies a tilt-table test method for estimating the steady-state rollover threshold of a heavy commercial vehicle or bus, i.e. the maximum lateral acceleration that the test vehicle could sustain in steady-state turning without rolling over. It is applicable to complete roll units/combinations of roll-coupled vehicle units -- e.g. single-unit vehicles, tractor-semitrailer combinations, articulated buses, full trailers, B-train combinations -- of commercial vehicles, commercial vehicle combinations, buses or articulated buses as defined in ISO 3833, and under Categories M3, N2, N3, O3 and O4 of ECE and EC vehicle regulations (trucks and trailers with maximum weights above 3,5 t and buses and articulated buses with maximum weights above 5 t).

Véhicules utilitaires lourds et autobus — Seuil statique de renversement — Méthode d'essai du plateau incliné

General Information

• Status: Withdrawn
• Publication Date: 31-Aug-2004
• Withdrawal Date: 31-Aug-2004
• ICS: 43.080.01 - Commercial vehicles in general
• Technical Committee: ISO/TC 22 - Road vehicles
• Drafting Committee: ISO/TC 22 - Road vehicles
• Current Stage: 9599 - Withdrawal of International Standard
• Completion Date: 11-Feb-2011

Relations

• Revised: ISO 16333:2011 - Heavy commercial vehicles and buses — Steady-state rollover threshold — Tilt-table test method
• Effective Date: 21-Aug-2010
• Consolidated By: ISO 6185-3:2014 - Inflatable boats — Part 3: Boats with a hull length less than 8 m with a motor rating of 15 kW and greater
• Effective Date: 06-Jun-2022

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 16333
First edition
2004-08-15

Heavy commercial vehicles and buses —
Steady-state rollover threshold —
Tilt-table test method
Véhicules utilitaires lourds et autobus — Seuil statique de
renversement — Méthode d'essai du plateau incliné




Reference number
ISO 16333:2004(E)
©
ISO 2004

---------------------- Page: 1 ----------------------
ISO 16333:2004(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.


©  ISO 2004
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 [e-mail]
Web www.iso.org
Published in Switzerland

ii © ISO 2004 – All rights reserved

---------------------- Page: 2 ----------------------
ISO 16333:2004(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope. 1
2 Normative references. 1
3 Terms and definitions. 1
4 Principle. 3
5 Variables. 4
6 Measuring equipment. 5
7 Test conditions. 5
8 Test procedure. 6
9 Data analysis. 9
Annex A (normative) Test report — Additional test conditions . 13
Annex B (informative) Error sources. 14

© ISO 2004 – All rights reserved iii

---------------------- Page: 3 ----------------------
ISO 16333:2004(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 16333 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 9, Vehicle
dynamics and road-holding ability.
iv © ISO 2004 – All rights reserved

---------------------- Page: 4 ----------------------
ISO 16333:2004(E)
Introduction
The dynamic behaviour of heavy road vehicles is a most important part of active vehicle safety. Any given
heavy commercial vehicle or bus, together with its driver and the prevailing environment, forms a unique
closed-loop system. The task of evaluating the dynamic behaviour is therefore very difficult since there is a
significant interaction between these driver–vehicle–environment elements, each of which is complex in itself.
Moreover, insufficient knowledge is available concerning the relationship between overall vehicle-dynamic
properties and accident avoidance. Since the number of variants of heavy vehicles is tremendously large,
each vehicle is unique. Accordingly, results obtained using this test method apply only to the individual test
vehicle and not to other vehicles, regardless of how similar they may appear to be.
Test conditions also have a strong influence on test results. Therefore, only vehicle-dynamic properties
obtained under virtually identical test conditions are comparable to one another.
Additionally, this International Standard is limited to the specification of a method for estimating the steady-
state rollover threshold of heavy commercial vehicles and buses. While this property is known to be an
important component of the dynamic roll stability, it is not the only component. In particular, this document in
no way accounts for the advantages that can result from the use of dynamic roll-stability control systems, and
cannot alone be considered sufficient to establish a complete overview of the roll stability of a heavy
commercial vehicle or bus.

© ISO 2004 – All rights reserved v

---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 16333:2004(E)

Heavy commercial vehicles and buses — Steady-state rollover
threshold — Tilt-table test method
1 Scope
This International Standard specifies a tilt-table test method for estimating the steady-state rollover threshold
of a heavy commercial vehicle or bus, i.e. the maximum lateral acceleration that the test vehicle could sustain
in steady-state turning without rolling over.
It is applicable to complete roll units/combinations of roll-coupled vehicle units — e.g. single-unit vehicles,
tractor–semitrailer combinations, articulated buses, full trailers, B-train combinations — of commercial vehicles,
commercial vehicle combinations, buses or articulated buses as defined in ISO 3833, and under Categories
M3, N2, N3, O3 and O4 of ECE and EC vehicle regulations (trucks and trailers with maximum weights above
3,5 t and buses and articulated buses with maximum weights above 5 t).
It does not cover transient, vibratory or dynamic rollover situations; nor does it consider the influences of
dynamic stability control systems. Furthermore, the quality of the estimate of the steady-state rollover
threshold provided by the test method decreases as the tilt angle required to produce rollover increases. Even
so, the results for heavy vehicles with high rollover thresholds can be used for comparing their relative steady-
state roll stability.
NOTE For further limitations of the specified test method, see Annex B.
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 3833, Road vehicles — Types — Terms and definitions
ISO 8855, Road vehicles — Vehicle dynamics and road-holding ability — Vocabulary
ISO 15037-2:2002, Road vehicles — Vehicle dynamics test methods — Part 2: General conditions for heavy
vehicles and buses
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 8855 and ISO 15037-2, and the
following apply.
3.1
critical tilt angle
φ
Tc
angle at which critical wheel lift occurs
© ISO 2004 – All rights reserved 1

---------------------- Page: 6 ----------------------
ISO 16333:2004(E)
3.2
critical wheel lift
first moment at which one or more wheels lift from the table surface, following which, stable roll equilibrium of
the vehicle cannot be established
3.3
roll unit
essentially self-supporting combination of roll-coupled vehicle units, the combination being free to roll
independently of other units
NOTE Typically, vehicle units joined by fifth-wheel couplings (which provide roll coupling) belong to the same roll unit,
while vehicle units joined by pintle hitches (which do not provide roll coupling) belong to different roll units. Roll units
including converter dollies could require minor vertical support at the drawbar pintle hitch.
3.4
steady-state rollover threshold
maximum magnitude of lateral acceleration that a vehicle can sustain during steady-state cornering on a flat
surface without rolling over
3.5
tilt angle
φ
T
angle between the horizontal and a vector that is in the plane of the tilt-table surface and is perpendicular to
the tilt axis
3.6
tilt-table
apparatus for supporting a vehicle on its tyres on a nominally planar surface and for tilting the vehicle in roll by
tilting that surface about an axis nominally parallel to the X-axis of the vehicle
NOTE A tilt-table can be composed either of a single structure supporting all tyres of the vehicle on a contiguous
surface or of multiple structures supporting one or more axles on separate, but nominally coplanar, surfaces.
3.7
tilt-table ratio
TTR
tan (φ ), i.e., tan(φ ), at the occurrence of critical wheel lift
Tc T
3.8
trip rail
rail or kerb fixed to the tilt-table surface and oriented longitudinally beside the low-side tyre(s) in order to
prevent the tyre(s) from sliding sideways
3.9
th
wheel lift of the i axle
l
wi
th
condition in which either all left or all right tyres of the i axle are out of contact with the surface of the tilt-table
NOTE It is a logical variable with values of 1 (true) or 0 (false).
2 © ISO 2004 – All rights reserved

---------------------- Page: 7 ----------------------
ISO 16333:2004(E)
4 Principle
The tilt-table test is a physical simulation of the roll-plane behaviour of a vehicle in a quasi-steady-state turn of
gradually increasing severity. In this test, the vehicle is mounted on a tilt-table with the vehicle's longitudinal
axis located parallel to an axis about which the table can be tilted. The tilt-table is then gradually tilted up to
the point at which the vehicle becomes unstable in roll. Safety restraints are used to prevent the actual rollover
of the vehicle.
When the table is at a non-zero tilt angle, the test simulates a non-vibratory steady turn. As shown in Figure 1,
the component of gravitational forces parallel to the table surface provides a simulation of the centrifugal
forces experienced by a vehicle in turning manoeuvres. The progressive application of these forces by slowly
tilting the table serves to simulate the effects of quasi-statically increasing lateral acceleration in steady turning
manoeuvres.
When the table is tilted, the centrifugal force is simulated by the component of the gravitational force parallel
to the table surface, m⋅g⋅sin(φ ), and the weight of the vehicle is simulated by the component of the
T
gravitational force that is perpendicular to the table, m⋅g⋅cos(φ ), where m is the mass of the vehicle, g is the
T
gravitational acceleration and φ is the tilt angle. Since the primary mechanism of actual rollover depends on
T
the ratio of the centrifugal forces to the vertical forces, it is appropriate to take the ratio of the simulated lateral
acceleration forces to the simulated weight to represent the lateral acceleration. At the moment of roll
instability, i.e. when critical wheel lift occurs, the tangent of the tilt angle, i.e. the tilt-table ratio (TTR), is an
estimate of the steady-state rollover threshold, expressed in gravitational units:
mg× sin φ
( )
Tc
TTR≡=tan φ (1)
()
Tc
mg× cos φ
()
Tc
As the vehicle is progressively tilted during the tilt-table test, vertical load is progressively transferred from
tyres on one side of the vehicle to tyres on the other side. Tyres on the unloaded side will eventually lift off of
the table surface. Typically, wheel lift does not take place simultaneously for all axles; rather, lift-off occurs at
different axles at different angles of tilt. Tyres that lift off of the table early in the process may rise well off the
table surface before the critical wheel lift occurs and the vehicle becomes unstable in roll. It is often the case
that the vehicle will become unstable even though all tyres of one or more axles (often the steer axle) remain
firmly on the table surface. The tilting motion of the table should be stopped simultaneously with the vehicle
becoming unstable in roll, and safety restraints should be arranged to arrest the roll motion of the vehicle
immediately following that critical tyre-lift event.
Annex B presents further discussion of the tilt-table test method dealing with conceptual and practical sources
of error.
© ISO 2004 – All rights reserved 3

---------------------- Page: 8 ----------------------
ISO 16333:2004(E)

Key
1 simulated centrifugal force = m⋅g⋅sin(φ )
T
2 actual weight = m⋅g
3 simulated weight = m⋅g⋅cos(φ )
T
Figure 1 — Schematic diagram of tilt-table test
5 Variables
The following variables shall be determined:
a) wheel lift at each axle (l );
wi
b) tilt angle at each axle of the vehicle (φ ).
Ti
Alternatively, where it is independently assured that all values of φ are within a range of ± 0,1°, tilt angle (φ )

Ti T
shall be determined.
Some or all of the following variables should be determined, in order to aid in analysing the vehicle’s
behaviour:
 roll angle(s) relative to the tilt-table surface at relevant positions on the sprung mass(es);
 roll angle(s) relative to the tilt-table surface of unsprung mass(es);
 lateral suspension deflections;
 tyre deflections;
 air-spring pressures;
 lateral deflections of relevant elements of the chassis or payload.
It is also recommended that the data record include event markers to indicate the occurrence of significant
events of interest, e.g. the transition through spring lash.
4 © ISO 2004 – All rights reserved

---------------------- Page: 9 ----------------------
ISO 16333:2004(E)
6 Measuring equipment
6.1 General
Measurement and recording equipment shall be in accordance with ISO 15037-2.
6.2 Description
All variables shall be measured by means of appropriate transducers, whose time histories should be
recorded by a multi-channel recording system. Typical operating ranges and recommended maximum errors
of the transducer recording systems for the variables not listed in ISO 15037-2 are shown in Table 1.
Table 1 — Typical operating ranges and recommended maximum errors of variables not listed in
ISO 15037-2
Recommended max. error of combined
Variable Typical operating range
system
Tilt angle(s) 40° ± 0,1°
Roll angles relative to the tilt-table surface 15° ± 0,1°
Lateral deflections ± 50 mm ± 1 mm
Air-spring inflation pressures 1 500 kPa 15 kPa

6.3 Data processing
The tilt-table test is a quasi-static test so that data processing concerns relating the natural frequencies of
vehicle responses and the frequency response of the instrument system do not apply in the usual manner.
However, the bandwidths of the analog data systems and the sampling rates of digitising systems, in
relationship to the maximum tilt rate of the table and the maximum roll rates of the vehicle and its components,
influence the overall accuracy of the measurement system. Specifications should be in accordance with
ISO 15037-2. In any case, the time response and latencies of all analog and digital elements of the
measurement system shall be properly considered in evaluating measurement accuracy.
7 Test conditions
7.1 General
Limits and specifications for the tilt-table, ambient conditions and vehicle test conditions indicated below shall
be maintained during the test. Any deviations shall be reported in the test report.
7.2 Tilt-table properties
The tilt-table facility shall have the properties given in Table 2. In addition, the tilt-table facility shall provide
lateral constraint of the vehicle through adequate surface friction or, optionally, through the use of a trip rail, as
specified in 8.1.2.
© ISO 2004 – All rights reserved 5

---------------------- Page: 10 ----------------------
ISO 16333:2004(E)
Table 2 — Tilt-table requirements
Property Requirement
Tilt angle variance at the positions of axle support ± 0,1°
Pivot axis alignment
Overall: Horizontal within ± 0,25°
Multiple axle tables: Co-linear within ± 2,5 mm
Minimum tilt rate < 0,05°/s
NOTE Specification of tilt angle variance implies requirements on table stiffness, surface flatness and/or alignment of individual
axle tables (see Annex B).

7.3 Ambient conditions
The ambient wind speed shall be u 2m/s.
Since, in certain cases, the temperature of vehicle components may influence test results, ambient
temperature shall be reported.
7.4 Test vehicle
7.4.1 General
The test vehicle shall be a complete, single roll unit.
The specifications of ISO 15037-2 shall apply except that items relating to test-induced changes in tyre
properties and to conditions and adjustments of the engine are moot. Items relating to other components of
the drive train may also not apply.
7.4.2 Self-regulating suspensions
For the standard test condition, if the test vehicle is equipped with height- or load-regulating suspensions,
suspension ride height or load shall be appropriately established before testing begins, and the active
adjustment function of the suspension shall be disabled during testing. Optionally, in some cases, e.g. when
the regulating system has a relatively fast response, it may be appropriate to allow self-regulation functions to
remain active during the tilt test. In either case, the state of the self-regulation shall be reported. Annex B
includes discussion on disabling self-regulating suspension features.
For height-regulating suspensions, reliable means shall be provided to identify the proper ride height within
± 5 mm during manual inflation. For load-regulating suspensions, reliable means shall be provided to identify
the proper inflation pressure within ± 5 % or ± 10 kPa, whichever is greater, during manual inflation.
8 Test procedure
8.1 Installation of vehicle on tilt-table
8.1.1 Alignment
For the standard test condition, the Xv-axis of each vehicle unit shall be parallel to the table pivot axis within
± 50 mm at each axle and, when applicable, at the coupling joints.
6 © ISO 2004 – All rights reserved

---------------------- Page: 11 ----------------------
ISO 16333:2004(E)
8.1.2 Lateral constraint
For the standard test condition, the surface of the tilt-table shall be such that tyre friction is adequate to
preclude the vehicle sliding sideways at the critical tilt angle. Additional safety restraints should be used to
arrest lateral motion in the event that the vehicle were to slide sideways on the table surface.
Optionally, a trip rail of any height up to the specified maximum may be provided immediately adjacent to the
low-side tyre of each axle such as to prevent the vehicle from sliding sideways at high tilt angles. The
maximum height of the trip rail shall be either 60 mm or two-thirds of the height between the wheel rim and the
tilt-table, whichever is larger. If a trip rail is used, the geometry of the trip rail shall be recorded.
NOTE 1 Table surfaces that achieve friction coefficients approaching unity are available. See Annex B.
NOTE 2 The use of trip rails can be expected to influence the result of the test by increasing TTR slightly. See Annex B.
8.1.3 Longitudinal constraint
Longitudinal constraint of the vehicle shall be accomplished by constraints applied at one, and only one, axle.
When applicable, the transmission shall be in neutral and differential locks shall not be applied.
The proper response of heavy vehicle suspensions during tilt tests typically requires small, but free
longitudinal motion of the axles. When individual axle tables are used, care should be taken that such motion
can safely take place on the surfaces of the tables.
If longitudinal constraint is provided by blocking tyres of a stee
...