No C 292/12 Official Journal of the European Communities 22. 11. 90 
Proposal for a Council Directive amending Directive 85/3/EEC on the weights, dimensions and 
certain technical characteristics of certain road vehicles 
COM(90) 486 final 
(Submitted by the Commission on 26 October 1990) 
(90/C 292/11) 
THE COUNCIL OF THE EUROPEAN COMMUNITIES, 
Having regard to the Treaty establishing the European Economic Community, and in 
particular Article 75 thereof, 
Having regard to the proposal from the Commission, 
Having regard to the opinion of the European Parliament, 
Having regard to the opinion of the Economic and Social Committee, 
Whereas, in the light of decisions made at the adoption of Council Directive 89/338/EEC (x) it 
is necessary to give an objective technical definition to the equivalence of air suspension; 
Whereas, in order to mitigate the negative effect on the road pavement and on certain bridge 
structures of the 11,5 tonnes drive axle of heavy commercial vehicles, that drive axle should be 
fitted with twin tyres and air suspension or suspension considered to be equivalent, 
Whereas the increased benefit of twin tyres and air suspension or its equivalence should permit 
the use of the 11,5 tonne drive axle and whereas if the drive axle is not equipped with twin 
tyres and air suspension or its equivalent its maximum authorized weight should be limited to 
10,5 tonnes, 
Whereas measures to reduce the adverse effect of axle weight (both static and dynamic) on the 
road pavement and bridges should not prejudice the vehicle's safety, in particular its stability 
and braking characteristics, indeed these qualities should be enhanced, 
Whereas this proposal can be considered as the first step towards prescribing requirements for 
vehicle axles and axle groups that take full account of the need to mitigate as far as possible 
the negative effect of the total vehicle on road and bridge structures; 
Whereas Council Directive 85/3/EEC (2), as last amended by Directive 89/461/EEC (3), 
should be amended accordingly, 
(') OJ No L 142, 25. 5. 1989, p. 3. 
(2) OJ No L 2, 3. 1. 1985, p. 14. 
(3) OJ No L 226, 3. 8. 1989, p. 7. 
22. 11.90 Official Journal of the European Communities NoC 292/13 
HAS ADOPTED THIS DIRECTIVE: 
Article 1 
Directive 85/3/EEC is hereby amended as follows: 
1. The following third and fourth paragraphs are added to Article 4: 
'3. For vehicles refered to in Annex I which are first put into circulation from January 
1993 the provisions of Article 3 (1) shall apply when the drive axle is at its maximum auth­
orized weight of 11,5 tonnes and where it is equipped with twin tyres and air suspension or 
suspension recognized as being equivalent within the Community as defined in Annex III. 
4. Where the drive axle of any vehicle referred to in the third paragraph is not equipped 
with twin tyres and air suspension or suspension recognized as being equivalent within the 
Community as defined in Annex III then the maximum authorized weight of that drive axle 
shall be limited to 10,5 tonnes.' 
2. Annex I is amended as follows: 
Paragraph 2.2.4.2: 
'2.2.4.2. is greater than 1.8 m 36 tonnes + 2 tonnes of margin when the 
MAW of the motor vehicle (18 tonnes) and 
the MAW of the tandem axle of the semi 
trailer (20 tonnes) are respected and the 
driving axle is fitted with twin tyres and air 
suspension or suspension recognized as 
being equivalent within the Community as 
defined in Annex III.' 
Paragraph 2.3.2: 
'2.3.2. Three-axle motor vehicles 25 tonnes, 
26 tonnes where the driving axle is fitted 
with twin tyres and air suspension 
or suspension recognized as being 
equivalent within the Community as de­
fined in Annex III.' 
Paragraph 2.3.3: 
'2.3.3. Four-axle motor vehicles with 
two steering axles 32 tonnes where the driving axle is fitted 
with twin tyres and air suspension 
or suspension recognized as being 
equivalent within the Community as de­
fined in Annex III.' 
Paragraph 3.5.3: 
'3.5.3. 1,3 m or greater but less than 
1,8 m (1,3 m < d < 1,8 m) 18 tonnes 
19 tonnes where the driving axle is fitted 
with twin tyres and air suspension 
or suspension recognized as being 
equivalent within the Community as de­
fined in Annex III.' 
3. A new Annex III is added as set out in the Annex hereto. 
No C 292/14 Official Journal of the European Communities 22. 11. 90 
Article 2 
1. The Member States shall, after consultation with the Commission, bring into force the 
laws, regulations and administrative provisions necessary to comply with this Directive not later 
than 1 January 1993. 
When Member States adopt these provisions, these shall contain a reference to this Directive or 
shall be accompanied by such reference at the time of their official publication. The procedure 
for such reference shall be adopted by Member States. 
2. Member States shall forthwith communicate to the Commission the provisions of national 
law which they adopt in the field covered by this Directive. 
Article 3 
This Directive is addressed to the Member States. 
ANNEX 
ANNEX III 
Conditions relating to the use of the 11,5 tonne drive axle (or any drive axle with a maximum authorized 
weight above 10,5 tonnes) 
1. Drive axles 
The drive axle at a maximum authorized weight above 10,5 tonnes shall be fitted with twin tyres and be 
supported by a suspension system as defined in paragraphs 3 and 4. 
2. Tyre contact pressure 
Tyre contact pressure must not be greater than 8 bars. 
3. Definition of air suspension 
A suspension system is considered to be air suspended if at least 75 % of the spring effect is caused by 
the air spring. 
4. Equivalence to air suspension 
A suspension recognized to be equivalent to air suspension must conform to the following: 
4.1. During free transient low frequency vertical oscillation of the sprung mass above a drive axle or 
bogie, the measured frequency and damping with the suspension carrying its maximum load must 
comply with the limits defined in paragraphs 4.2 to 4.5. 
4.2. Each axle must be fitted with hydraulic dampers. On tandem axle bogies the dampers must be 
positioned to minimize the oscillation of the bogies. 
4.3. The mean damping ratio D must be more than 20 % of critical damping for the suspension in its 
normal condition with hydraulic dampers in place and operating. 
4.4. The damping ratio d of the suspension with all hydraulic dampers removed or incapacitated must 
be not more than 50 % of D. 
22. 11. 90 Official Journal of the European Communities No C 292/15 
4.5. The frequency of the sprung mass above the drive axle or bogie in a free transient vertical oscil­
lation must not be higher than 2,0 Hz. 
4.6. The definition of the frequency and damping of the suspension is given in paragraph 5 and the test 
procedures for measuring the frequency and damping are laid down in paragraph 6. 
5. Definition of frequency and damping 
In this definition a sprung mass M kg above a drive axle or bogie is considered. The axle or bogie has a 
total vertical stiffness between the road surface and the sprung mass of k newtons/metre (N/m) and a 
total damping coefficient of C newtons per metre per second (N-s/m). The vertical displacement of the 
sprung mass is Z. The equation of motion for free oscillation of the sprung mass is 
d2 Z d Z 
M + C + kZ = 0 
dt2 dt 
The frequency of oscillation of the sprung mass F rad/sec is 
K C2 
M ~~ 4M7 
The damping is critical when C = Co, where 
Co = 2 1/ KM 
The damping ratio as a fraction of critical is C/Co. 
During free transient oscillation of the sprung mass the vertical motion of the mass will follow a 
damped sinusoidal path (Figure 2). The frequency can be estimated by measuring the time for as many 
cyles of oscillation as can be observed. The damping can be estimated by measuring the heights of 
successive peaks of the oscillation in the same direction. If the peak amplitudes of the first and second 
cycles of the oscillation are Ai and A2, then the damping ratio D is: 
C 1 Aj 
D = = In 
Co 2 K A2 
In is the natural logarithm of the amplitude ratio. 
6. Test procedure 
To establish by test the damping ratio D, the damping ratio with hydraulic dampers removed, and the 
frequency F of the suspension the loaded vehicle should either: 
(a) be driven at slow speed (5 km/h ± 1 km/h) over an 80 mm step with the profile shown in Figure 1. 
The transient oscillation to be analysed for frequency and damping occurs after the wheels on the 
drive axle have left the step; 
or 
(b) be pulled down by its chassis so that the drive axle load is 1,5 times its maximum static value. The 
vehicle hold down is suddenly released and the subsequent oscillation analysed; 
or 
(c) be pulled up by its chassis so that the sprung mass is lifted by 80 mm above the drive axle. The 
vehicle hold up is suddenly dropped and the subsequent oscillation analysed. 1/ 
No C 292/16 Official Journal of the European Communities 22. 11. 90 
The vehicle should be instrumented with a vertical displacement transducer between drive axle and 
chassis, directly above the drive axle. From the trace the time interval between the first and second 
compression peaks can be measured to obtain the frequency F and the amplitude ratio to obtain the 
damping. For twin drive bogies, vertical displacement transducers should be fitted between each drive 
axle and the chassis directly above it. 
Figure 1 
Step for suspension tests 
Direction of travel 10-20 mm radius 
Figure 2 
A damped transient response