INTERNATIONAL

STANDARD 612
INTERNATIONAL ORGANIZATION FOR STANDARDlZATlON*MEWIYHAPOfiHAR OPrAHM3AlWlR ll0 CTAH~APTH3AlJMM.ORGANlSATlON INTERNATIONALE DE NORMALISATION

Road vehicles - Dimensions

of motor vehicles and towed
les - Terms and definitions
Ve’hicules rou tiers - Dimensions des au tomobiles et velhicules tract& - D&ominations et de’finitions

First edition - 1978003115

Corrected and reprinted -
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ISO 612:1978
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UDC 629.11.071.1 Ref. No. IS0 6124978 (E)

Descriptors : road vehicles, motor vehicles, towed road vehicles, dimensions, vocabulary.

Price based on 15 pages

 FOREWORD

IS0 (the International Organization for Standardization) is a worldwide federation

of national standards institutes (IS0 member bodies). The work of developing
International Standards is carried out through IS0 technical committees. Every
member body interested in a subject for which a technical committee has been set
up 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.

Draft International Standards adopted by the technical committees are circulated

to the member bodies for approval before their acceptance as International
Standards by the IS0 Council.

International Standard IS0 612 was developed by Technical Committee

iTeh STANDARD PREVIEW
ISO/TC 22, Road vehicles, and was circulated to the member bodies in
november 1976.
(standards.iteh.ai)
It has been approved by the member bodies of the following countries :
ISO 612:1978
Austria https://standards.iteh.ai/catalog/standards/sist/fc329d0a-f624-4446-841d-
I ran New Zealand
Brazil Italy Poland
618444639727/iso-612-1978
Bulgaria Japan - Romania
France Korea, Dem. P. Rep. of South Africa, Rep. of
Germany Korea, Rep. of Spain
Hungary Mexico Sweden
India Netherlands Switzerland

The member bodies of the fol lowing countries expressed disapproval of the
document on technica grounds :

Australia
Belgium
United Kingdom

This International Standard cancels and replaces IS0 Recommendation

R 6124967, of which it constitutes a technical revision.

0 International Organization for Standardization, 1978 l

Printed in Switzerland

ii
 CONTENTS Page

1 Scope ............................................ 1

2 Field of application. .................................. 1

3 References. ........................................ 1

4 General ........................................... 1

5 Definition of the longitudinal median plane (of the vehicle) ........ 2

6 Terms and definitions of dimensions of motor vehicles and

towed vehicles ...................................... 3

6.1 Vehicle length .................................... 3

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6.2 Vehicle width. .................................... 4

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6.3 Vehicle height (unladen) ............................. 4

6.4 Wheel space. ..................................... 5

ISO 612:1978 6
6.5 Track ..........................................
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Front overhang. ...................................
6.6 618444639727/iso-612-1978 6

6.7 Rear overhang .................................... 6

6.8 Ground clearance .................................. 7

6.9 Rampangle ...................................... 7

6.10 Approach angle ................................... 7

6.1 1 Departure angle ................................... 7

6.12 Height of chassis above ground (commercial vehicles) .......... 8

6.13 Maximum usable length of chassis behind cab

(vehicle with cab) .................................. 8

6.14 Bodywork length .................................. 8

6.15 Maximum internal dimensions of body

(commercial vehicles) ............................... 9

6.16 Drawgear length ................................... 9

6.17 Drawbar length. ................................... 10

6.18 Position of towing attachment. ......................... 10

6.19 Fifth wheel lead. .................................. 11

6.20 Height of coupling face .............................. 11

6.21 Distance between towing device and front end of

towing vehicle .................................... 12

. ..
III
6.22 Rear tractor clearance radius of semi-trailer ................. 12

6.23 Front fitting radius of semi-trailer .......................

12

6.24 Camber angle. .................................... 12

6.25 Kingpin inclination. ................................ 13

6.26 Kingpin offset .................................... 13

6.27 Toe-in .......................................... 13

6.28 Castor .......................................... 14

6.29 Vertical clearance. ................................. 14

6.30 Lift ........................................... 14

6.31 Turning locks. .................................... 14

6.32 Turning clearance circles ............................. 15

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iv
INTERNATIONAL STANDARD IS0 6124978 (E)

Road vehicles - Dimensions of motor vehicles and towed

vehicles - Terms and definitions

1 SCOPE 3 REFERENCES

This International Standard defines terms relating to I SO 1176, Road vehicles - Weights - Vocabulary
dimensions of motor vehicles and towed vehicles.
IS0 1726, Road vehicles - Mechanical coupling between
It does not deal with methods of measurement, the units trac tars and semi- trailers - Interchangeability.
used in reporting the results or the accuracy required or
IS0 3833, Road vehicles - Types -. Temns and definitions.
the order of magnitude ofthe dimensions defined.

NOTE - Other terms, definitions

iTeh STANDARDsystem
and
IS0PREVIEW
4 130, Road vehicles -
symbols are given
and fiducial marks.’ 1
in the
Threedimensional reference
following International Standards :

IS0 3877/l, Tyres, valves and tubes

(standards.iteh.ai)
- List of equivalent terms -
Part I : Tyres. 4 GENERAL
IS0 38771 I I, Tyres, valves and tubes - List ISO 612:1978
of equivalent
- terms
Unless otherwise stated with regard to one or more of the
Part II : Tyres valves. https://standards.iteh.ai/catalog/standards/sist/fc329d0a-f624-4446-841d-
items mentioned below, it should be understood that :
IS0 3877/l I I, Tyres, valves 618444639727/iso-612-1978
and tubes - List of equivalent terms -
Part Ill : Tubes. a) the supporting surface is horizontal; lengths and
IS0 3911, Wheels/rims - Nomenclature, designation, marking, and widths are measured in the horizontal plane, and heights
units of measurement. in the vertical plane;
I SO 4 13 1, Road vehicles - Dimensional symbols for passenger
b) the total weight of the vehicle is the maximum
cars. 1)
authorized total weight (see IS0 1176), the load being
IS0 4223/l, Definitions of some terms used in the tyre industry - distributed according to the manufacturer’s instructions;
Part I : Pneumatic tyres.
c) the tyres are inflated to the pressure corresponding
to the maximum authorized total weight of the vehicle;
2 FIELD OF APPLICATION
d) the vehicle is stationary; its doors and windows are
The provisions of this International Standard apply to closed, and its wheels and articulated elements are in
motor vehicles and towed vehicles as defined in IS0 3833 positions corresponding to movements in a straight line;
(terms 3.1 and 3.2). e) the vehicle is new from the factory and normally
This International Standard does not cover road vehicles equipped;
such as motorcycles and mopeds, or other vehicles, such f) all wheels of the vehicle are resting on the ground;
as agricultural tractors, which are only incidentally used
for the carriage of persons or goods by road or for towing g) the expression “mid-plane of the wheel”, that occurs
on the road vehicles used for the carriage of persons or in a number of definitions, designates the plane
goods. equidistant from the inner edges of the rim.

1) At present at the stage of draft.

1
IS06124978 (E)

5 DEFINITION OF THE LONGITUDINAL MEDIAN

PLANE (OF THE VEHICLE)

longitudinal median plane (of the vehicle) : The vertical

plane Y passing through the mid-points of AB,
perpendicular to AB, A and B being defined as follows :
as follows :
(4 (A)
- for each wheel, the vertical plane passing through
its axis cuts the mid-plane of the wheel [see g), clause 41
following a straight line A which meets the supporting
surface of the vehicle at one point; I

- A and B are two points thus defined which corre-

spond to two wheels, both of which are either steering
or powered wheels, situated respectively at the two ends
of the same real or imaginary axle.
4
NOTES A A B
1 The longitudinal median plane (of the vehicle) is also called the
I,
“longitudinal plane of symmetry” or “zero Y plane (see IS0 4130). “I
2 Case of dual wheels
The mid-plane of the dual wheels is equidistant from the inner
edge of one wheel and the outer edge of the other. The straight
line A is, in this particular case, the intersection of the mid-plane
of the dual wheels and the vertical plane passing through the axis
of the axle pin. \
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 IS06124978 (E)

6 TERMS AND DEFINITIONS OF MOTOR VEHICLES AND TOWED VEHICLES

.
Term Definition Drawing

vehicle length See 6.1 .l to 6.1.3.

motor vehicle The distance between two

length vertical planes perpendicular to
the longitudinal median plane
(of the vehicle) (see clause 5)
and touching the front and rear
of the vehicle respectively.
NOTE - All parts of the vehicle,
including any parts projecting from
front or rear (towing-hooks,
bumpers, etc.) are contained between
these two planes.

1.2 trailer length

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The lengths with and without
(standards.iteh.ai)
drawgear, defined as in 6.1 .I,
the second value being placed
in parentheses :
ISO 612:1978
Example : 5 500 (3 700)
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NOTE 618444639727/iso-612-1978
- To determine the length
with drawgear, the drawbar is
assumed to be located so that the
axis of the drawbar eye or coupling
head is vertical and lies within the
foremost vertical plane.

1.3 semi-trailer The length of the semi-trailer,

length defined as in 6.1.1, and the
distance between kingpin axis
and rear end of semi-trailer, the
second value being placed in
parentheses :

Example : 10 800 (7 800)

lSO612-1978 (E)

No. Term Definition Drawing

6.2 vehicle width The distance between two planes

parallel to the longitudinal
median plane (of the vehicle)
(see clause 5) and touching the
vehicle on either side of the
said plane.

NOTE - All parts of the vehicle,

R
including any lateral .projections
of fixed parts (wheel hubs, door-
handles, bumpers, etc.) are contained
between these two planes, except
the rear-view mirrors, side marker
lamps, We pressure indicators,
direction
lights,
indicator
customs
lamps,
seals, flexible
position
mud-
I I
guards, retractable steps, snow chains
and the deflected part of the tyre
walls immediately above the point
of contact with the ground.

6.3 vehicle height

(unladen) supporting
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The ’ distance between
su rface and
the
a
horizontal
(standards.iteh.ai)
plane touching
topmost part of a vehicle.
the

NOTES ISO 612:1978 t

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1 All fixed parts of the vehicle are
contained between these two618444639727/iso-612-1978
planes.
‘1
2 The vehicle is in operating order I r .
and unladen. 0
-p

4
 lSO612-1978 (E)

No. Term Definition Drawing 1

6.4 wheel space See 6.4.1 and 6.4.2.

6.4.1 motor vehicle The distance between the

or trailer wheel perpendicular lines constructed
space to the longitudinal median plane
(of the vehicle) (see clause 5)
from the previously defined
points A or B corresponding to
two consecutive wheels situated
on the same side of the vehicle.

NOTES

1 If the values of right and left wheel

spaces are different, both dimensions
are stated, separated by a dash,
the first corresponding to the left
wheels.
2 For vehicles with three or more
axles, the wheel spaces between
consecutive wheels are indicated,
going from the foremost to the
rearmost wheel : the total wheel
space for right or for left is the sum
of these distances.
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6.4.2 semi-trailer The distance from the axis of

wheel space the fifth wheel kingpin in a
vertical position to the vertical
plane through the axis of the
semi-trailer’s first axle.

NOTE - In the case of a semi-trailer

with two or more axles, the same
rule should be applied as for vehicles
with three or more axles.
IS0 612-1978 (E)

No. Term Definition Drawing

6.5 track The track corresponding to a

real or imaginary axle is the B
sum of the two distances AH
and BH in relation to the two
wheels connected to this axle, H
AH and BH being the distances H
from points A and B defined in
clause 5 to the longitudinal
median plane (of the vehicle).
A
NOTES
1 Practical brief definition : In the
case of two single wheels corre-
sponding to the same real or
imaginary axle, the track is rep-
resented by the distance between the
axes of the traces left by the wheels
on the supporting surface.
2 Case of dual wheels

See note 2 of clause 5.

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6.6 front overhang The distance between the

vertical plane passing through
the centres of the front wheels
and the foremost point of the
vehicle, taking into consider-
ation lashing hooks, registration
number plate, etc., and any
parts rigidly attached to the
vehicle.

6.7 rear overhang The distance between the

vertical plane passing through
the centres of the rearmost
wheels and the rearmost point
of the vehicle, taking into

Y
consideration the towing
attachment, registration number
plate, etc., and any parts rigidly
attached to the vehicle.
 IS0 6124978 (E)

No. Term Definition Drawing

6.8 ground The distance between the

clearance ground and the lowest point of
the centre part of the vehicle.
The centre part is that part
contained between two planes
parallel to and equidistant from
the longitudinal median plane
(of the vehicle) (see clause 5)
and separated by a distance
which is 80 % of the least
distance between points on the
inner edges of the wheels on any
one axle.

6.9 ramp angle The minimum acute angle

between two planes, perpen-
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’ dicular to the longitudinal
median plane of the vehicle, tan-
(standards.iteh.ai)
gential, respectively, to the tyres
of the front and the rear wheels,
static loaded, and intersecting
at a line touching the lower ISOpart
612:1978
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of the vehicle, outside these
wheels. This angle defines the
618444639727/iso-612-1978
largest ramp over which the
vehicle can move.

6.10 approach The greatest angle between the

angle horizontal plane and planes
tangential to the static loaded
front wheel tyres, such that no
point of the vehicle ahead of
the axle lies below these planes
and that no part rigidly attached
to the vehicle lies below these . 1)
planes.

6.11 departure The greatest angle between the

angle horizontal plane and planes
tangential to the static loaded
rear wheel tyres, such that no
point of the vehicle behind
the axle lies below these
planes and that no part rigidly
attached to the vehicle lies
below these planes.