Council Directive of 26 July 1971 on the approximation of the laws of the Member States relating to the braking devices of certain categories of motor vehicles and of their trailers (71/320/EEC) (repealed)

[F1 ANNEX II U.K. Braking Tests and performance of braking systems

Textual Amendments

F1 Substituted by Commission Directive 98/12/EC of 27 January 1998 adapting to technical progress Council Directive 71/320/EEC on the approximation of the laws of the Member States relating to the braking devices of certain categories of motor vehicles and their trailers (Text with EEA relevance).

1. BRAKING TESTS U.K.

1.1. General U.K.

1.1.1. The performance prescribed for braking systems shall be based on the stopping distance and/or the mean fully developed deceleration. The performance of a braking system shall be determined by measuring the stopping distance in relation to the initial speed of the vehicle and/or by measuring the mean fully developed deceleration during the test. U.K.

1.1.2. The stopping distance shall be the distance covered by the vehicle from the moment when the driver begins to actuate the control of the braking system until the moment when the vehicle stops; the initial vehicle speed (v ₁ ) shall be the speed at the moment when the driver begins to actuate the control of the braking system; the initial speed shall not be less than 98 % of the prescribed speed for the test in question. The mean fully developed deceleration d _m shall be calculated as the deceleration averaged with respect to distance over the interval v _b to v _e according to the following formula: U.K.

where

V ₁

=

as defined above

V _b

=

vehicle speed at 0,8 V ₁  km/h

V _e

=

vehicle speed at 0,1 V ₁  km/h

S _b

=

distance travelled between V ₁ and V _b in metres

S _e

=

distance travelled between V ₁ and V _e in metres.

The speed and distance shall be determined using instrumentation having an accuracy of ± 1 % at the prescribed speed for the test. The d _m may be determined by other methods than the measurement of speed and distance; in this case, the accuracy of the d _m shall be within ± 3 %.

1.1.3. For the type-approval of any vehicle, the braking performance shall be measured during road tests conducted in the following conditions: U.K.

1.1.3.1. The vehicle's condition as regards mass shall be as prescribed for each type of test and be specified in the test report, (Annex IX, Appendix 2). U.K.

1.1.3.2. The test shall be carried out at the speeds prescribed for each type of test. Where a vehicle is so constructed that its maximum speed is lower than that prescribed for a test, the test shall be performed at the maximum speed of the vehicle. U.K.

1.1.3.3. During the tests, the force applied to the control of the braking system in order to obtain the prescribed performance shall not exceed the maximum force laid down for the test vehicle's category. U.K.

1.1.3.4. Without prejudice to the requirements contained in point 1.1.4.2, the road shall possess a surface having good adhesion. U.K.

1.1.3.5. The tests shall be performed when there is no wind liable to affect the results. U.K.

1.1.3.6. At the start of the tests the tyres shall be cold and at the pressure prescribed for the load actually borne by the wheels when the vehicle is stationary. U.K.

1.1.3.7. The prescribed performance shall be obtained without locking of the wheels, without deviation of the vehicle from its course, and without abnormal vibration. Wheel-locking is permitted where specifically mentioned. U.K.

1.1.4. Behaviour of the vehicle during braking U.K.

1.1.4.1. In braking tests, and in particular in those at high speed, the general behaviour of the vehicle during braking shall be checked. U.K.

1.1.4.2. The braking behaviour of vehicles of categories M, N, O ₃ and O ₄ on a road surface having reduced adhesion shall fulfil the conditions laid down in the Appendix to this Annex. U.K.

1.2. Type O test (ordinary performance test with brakes cold) U.K.

1.2.1. General U.K.

1.2.1.1. The brakes shall be cold. A brake is deemed to be cold when the temperature measured on the disc or on the outside of the drum is below 100 °C. U.K.

1.2.1.2. The test shall be conducted in the following conditions: U.K.

1.2.1.2.1. The vehicle shall be laden, the distribution of its mass among the axles being that stated by the manufacturer. Where provision is made for several arrangements of the load on the axles the distribution of the maximum mass among the axles shall be such that the load on each axle is proportional to the maximum permissible load for each axle; in the case of tractive units for semi-trailers, the load may be re-positioned approximately half-way between the kingpin position resulting from the above loading conditions and the centreline of the rear axle(s). U.K.

1.2.1.2.2. Every test shall be repeated on the unladen vehicle. In the case of a motor vehicle there may be, in addition to the driver, a second person on the front seat who is responsible for noting the results of the test. In the case of a motor vehicle designed to tow a semi-trailer, the unladen tests shall be conducted with the tractive unit only, without its trailer, but carrying a load representing the fifth wheel. It will also include a load representing a spare wheel, if this is included in the standard specification of the vehicle. In the case of a vehicle presented as a bare chassis-cab, a supplementary load may be added to simulate the mass of the body, not exceeding the minimum mass declared by the manufacturer in Annex XVIII. U.K.

1.2.1.2.3. The limits prescribed for minimum performance, both for tests with the vehicle unladen and for tests with the vehicle laden, are those laid down hereunder for each category of vehicle, the vehicle shall satisfy both the prescribed stopping distance and the prescribed mean fully developed deceleration for the relevant vehicle category, but it may not be necessary to actually measure both parameters. U.K.

1.2.1.2.4. The road shall be level. U.K.

1.2.2. Type O test with engine disconnected U.K.

1.2.2.1. The test shall be carried out at the speed prescribed for the category to which the vehicle belongs, the figures prescribed in this connection being subject to a certain margin of tolerance. The minimum performance prescribed for each category shall be attained. U.K.

1.2.3. Type 0 test with engine connected U.K.

1.2.3.1. Apart from the test prescribed in point 1.2.2, additional tests shall be carried out at various speeds with the engine connected, the lowest being equal to 30 % of the maximum speed of the vehicle and the highest being equal to 80 % of that speed. The maximum practical performance figures shall be measured and the behaviour of the vehicle shall be recorded in the test report. Tractive units for semi-trailers, artificially loaded to simulate the effects of a laden semi-trailer, shall not be tested beyond 80 km/h. U.K.

1.2.3.2. Further tests shall be carried out with the engine connected, from the speed prescribed for the category to which the vehicle belongs. The minimum performance prescribed for each category shall be attained. Tractive units for semi-trailers, artificially loaded to simulate the effects of a laden semi-trailer, shall not be tested beyond 80 km/h. U.K.

1.2.4. Type 0 test for vehicle of category O equipped with compressed-air brakes U.K.

1.2.4.1. The braking performance of the trailer can be calculated either from the braking rate of the towing vehicle plus the trailer and the measured thrust on the coupling or, in certain cases, from the braking rate of the towing vehicle plus the trailer with only the trailer being braked. The engine of the towing vehicle shall be disconnected during the braking test. In the case where only the trailer is braked, to take account of the extra mass being retarded, the performance will be taken to be the mean fully developed deceleration. U.K.

1.2.4.2. With the exception of cases according to points 1.2.4.3 and 1.2.4.4, it is necessary for the determination of the braking rate of the trailer to measure the braking rate of the towing vehicle plus the trailer and the thrust on the coupling. The towing vehicle shall meet the requirements laid down in the Appendix to point 1.1.4.2 of Annex II with regard to the relation between the ratio U.K.

and the pressure p _m . The braking rate of the trailer shall be calculated according to the following formula:

where:

Z _R

=

braking rate of the trailer

Z _R+M

=

braking rate of the towing vehicle plus the trailer

D

=

thrust on the coupling

(tractive force D > 0)

(compressive force D < 0)

P _R

=

total normal static reaction between road surface and wheels of the trailer

1.2.4.3. If a trailer has a continuous or semi-continuous braking system where the pressure in the brake actuators does not change during braking despite the dynamic axle load shifting, and in the case of semi-trailers, the trailer alone may be braked. The braking rate of the trailer shall be calculated according to the following formula: U.K.

where:

R

=

rolling resistance value = 0,01

P _M

=

total normal static reaction between road surface and wheels of towing vehicles for trailers

1.2.4.4. Alternatively, the evaluation of the braking rate of the trailer may be done by braking the trailer alone. In this case the pressure used shall be the same as that measured in the brake actuators during the braking of the combination. U.K.

1.3. Type I test (fade test) U.K.

1.3.1. With repeated braking U.K.

1.3.1.1. The service braking system of all motor vehicles shall be tested by successively applying and releasing the brakes a number of times, the vehicle being laden, in accordance with the conditions shown in the following table: U.K.

Category of vehicle	Conditions
	V 1 km/h	V 2 km/h	Δt (s)	n
M 1	80 % V max ≤ 120	½ V 1	45	15
M 2	80 % V max ≤ 100	½ V 1	55	15
M 3	80 % V max ≤ 60	½ V 1	60	20
N 1	80 % V max ≤ 120	½ V 1	55	15
N 2	80 % V max ≤ 60	½ V 1	60	20
N 3	80 % V max ≤ 60	½ V 1	60	20

where:

V ₁

=

refer to point 1.1.2

V ₂

=

speed at end of braking

V _max

=

maximum speed of the vehicle

n

=

number of times brakes applied

Δt

=

duration of a braking cycle (time elapsing between the initiation of one brake application and the initiation of the next).

1.3.1.2. If the characteristics of the vehicle do not allow for the period of time prescribed for Δt, the duration may be increased; in any event, in addition to the time necessary for braking and accelerating the vehicle, a period of 10 seconds shall be allowed in each cycle for stabilising the speed v ₁ . U.K.

1.3.1.3. In these tests, the force applied to the control shall be so adjusted as to attain a mean fully developed deceleration of 3 m/s ² at the first application of the brakes. This force shall remain constant throughout the succeeding brake applications. U.K.

1.3.1.4. During brake applications the highest gear ratio (excluding overdrive, etc.) shall be continuously engaged. U.K.

1.3.1.5. For regaining speed after braking, the gearbox shall be used in such a way as to attain the speed v ₁ in the shortest possible time (maximum acceleration allowed by the engine and gearbox). U.K.

1.3.2. With continuous braking U.K.

1.3.2.1. The service braking system of trailers of categories O ₂ and O ₃ shall be tested in such a manner that, the vehicle being laden, the energy input to the brakes shall be equivalent to that recorded in the same period of time with a laden vehicle driven at a steady speed of 40 km/h on a 7 % down gradient for a distance of 1,7 km. U.K.

1.3.2.2. The test may be carried out on a level road, the trailer being towed by a motor vehicle; during the test, the force applied to the control shall be adjusted so as to keep the resistance of the trailer constant (7 % of the maximum stationary axle load of the trailer). If the power available for hauling is insufficient, the test can be conducted at a lower speed but over a greater distance; as shown in the following table: U.K.

Speed (km/h)	Distance (metres)
40	1 700
30	1 950
20	2 500
15	3 100

1.3.3. Hot performance U.K.

1.3.3.1. At the end of the Type I test (test described in point 1.3.1 or test described in point 1.3.2 of this Annex) the hot performance of the service braking system shall be measured under the same conditions (and in particular at a constant control force no greater than the mean force actually used) as for the Type 0 test with the engine disconnected (the temperature conditions may be different). For motor vehicles, this hot performance shall not be less than 80 % of that prescribed for the category in question nor less than 60 % of the figure recorded in the Type 0 test with the engine disconnected. However in the case of trailers, the hot brake force at the periphery of the wheels when tested at 40 km/h shall not be less than 36 % of the maximum stationary wheel load, or less than 60 % of the figure recorded in the Type 0 test at the same speed. U.K.

1.3.3.2. In the case of a motor vehicle which satisfies the 60 % requirement specified in point 1.3.3.1, but which cannot comply with the 80 % requirement specified in point 1.3.3.1, a further hot performance test may be carried out using a control force not exceeding that specified in point 2.1.1.1 of this Annex. The results of both tests are entered in the report. U.K.

1.4. Type II test (downhill behaviour test) U.K.

1.4.1. Laden motor vehicles shall be tested in such a manner that the energy input is equivalent to that recorded in the same period of time with a laden vehicle driven at an average speed of 30 km/h on a 6 % down gradient for a distance of 6 km, with the appropriate gear engaged and the retarder, if the vehicle is fitted with one, being used. The gear engaged shall be such that the speed of the engine does not exceed the maximum value prescribed by the manufacturer. U.K.

1.4.2. For vehicles in which the energy is absorbed by the braking action of the engine alone, a tolerance of ± 5 km/h on the average speed shall be permitted, and the gear enabling the speed to be stabilised at the value closest to 30 km/h on the 6 % down gradient shall be engaged. If the performance of the braking action of the engine alone is determined by a measurement of deceleration, it shall be sufficient if the mean deceleration measured is at least 0,5 m/s ² . U.K.

1.4.3. At the end of the test, the hot performance of the service braking system shall be measured in the same conditions as for the Type 0 test with the engine disconnected (the temperature conditions, of course, may be different). This hot performance shall give a stopping distance not exceeding the following values and a mean fully developed deceleration not less than the following values, using a control force not exceeding 700 N: U.K.

category M ₃ :

(the second term corresponding to a mean fully developed deceleration of 3,75 m/s ² );

category N ₃ :

(the second term corresponding to a mean fully developed deceleration of 3,3 m/s ² ).

1.5. Type IIA test U.K.

1.5.1. Laden vehicles shall be tested in such a manner that the energy input is equivalent to that recorded in the same period of time with a laden vehicle driven at an average speed of 30 km/h on a 7 % down gradient for a distance of 6 km. During the test, the service, secondary and parking braking systems shall not be engaged. The gear engaged shall be such that the speed of the engine does not exceed the maximum value prescribed by the manufacturer. An integrated retarder may be used, provided that it is suitably phased such that the service braking system is not applied; this may be verified by checking that these brakes remain cold, as defined in point 1.2.1.1 of this Annex. U.K.

1.5.2. For vehicles in which the energy is absorbed by the braking action of the engine alone, a tolerance of ± 5 km/h on the average speed shall be permitted and the gear enabling the speed to be stabilised at the value closest to 30 km/h on a 7 % down gradient shall be engaged. If the performance of the braking action of the engine alone is determined by a measurement of deceleration, it shall be sufficient if the mean deceleration measured is at least 0,6m/s ² . U.K.

1.6. Type III test (Fade test for vehicles of category O ₄ ) U.K.

1.6.1. Track test U.K.

For the road test the conditions should be as follows:

Number of brake applications:	20
Duration of braking cycle:	60 s
Initial speed at the beginning of braking:	60 km/h
Braking applications:	corresponding to a trailer deceleration of 3 m/s 2

The braking rate of a trailer shall be calculated according to point 1.2.4.3 of this Annex:

The speed at the end of braking (Annex VII, appendix 1, point 3.1.5):

where:

Z _R

=

braking rate of the trailer

Z _R+M

=

braking rate of the vehicle combination (motor vehicle and trailer)

R

=

rolling resistance value = 0,01

P _M

=

total normal static reaction between the road surface and the wheels of trailer (kg)

P _R

=

total normal static reaction between the road surface and the wheels of towing vehicle for trailer (kg)

P ₁

=

part of the mass of the trailer borne by the unbraked axle(s) (kg)

P ₂

=

part of the mass of the trailer borne by the braked axle(s) (kg)

v ₁

=

initial speed (km/h)

v ₂

=

final speed (km/h)

1.6.2. Hot performance U.K.

At the end of the test according to point 1.6.1, the hot performance of the service braking system shall be measured under the same conditions as for the Type 0 test with, however, different temperature conditions and starting from an initial speed of 60 km/h. The hot brake-force at the periphery of the wheels shall not be less than 40 % of the maximum stationary wheel load, and not less than 60 % of the figure recorded in the Type 0 test at the same speed.

2. PERFORMACE OF BRAKING SYSTEMS U.K.

2.1. Vehicles of categories M and N U.K.

2.1.1. Service braking systems U.K.

2.1.1.1. Provisions relating to tests U.K.

2.1.1.1.1. The service braking systems of vehicles of categories M and N shall be tested under the conditions shown in the following table: U.K.

Type of test		M 1 0-I	M 2 0-I	M 3 0-I-II/IIA	N 1 0-I	N 2 0-I	N 3 0-I-II/IIA
Type 0 test with engine connected	prescribed speed	80 km/h	60 km/h	60 km/h	80 km/h	60 km/h	60 km/h
	s ≤
	d m  ≥	5,8 ms -2	5 ms -2
Type 0 test with engine disconnected	v = 80 % v max but ≤:	160 km/h	100 km/h	90 km/h	120 km/h	100 km/h	90 km/h
	s ≤
	d m  ≥	5 ms -2	4 ms -2
	F ≤	500 N	700 N

where:

v

=

test speed in km/h

s

=

stopping distance in m

d _m

=

mean fully developed deceleration at normal engine speed

F

=

force applied to foot control

v _max

=

maximum speed of the vehicle.

2.1.1.1.2. In the case of a motor vehicle authorised to tow an unbraked trailer, the minimum performance prescribed for the corresponding motor vehicle category (for the Type 0 test with engine disconnected) shall be attained with the unbraked trailer coupled to the motor vehicle and with the unbraked trailer laden to the maximum mass declared by the motor vehicle manufacturer. However, in the case of category M ₁ vehicles, the minimum combination performance shall be not less than 5,4 m/s ² both in laden and unladen conditions. U.K.

The combination performance shall be verified by calculations referring to the maximum braking performance actually achieved by the motor vehicle alone, laden, (and unladen in the case of M ₁ ) during the Type 0 test with engine disconnected, using the following formula (no practical tests with a coupled unbraked trailer are required):

where

d _M+R

=

calculated mean fully developed deceleration of the motor vehicle when coupled to an unbraked trailer in m/s ²

d _M

=

maximum mean fully developed deceleration of the motor vehicle alone achieved during the Type 0 test with engine disconnected in m/s ²

PM

=

mass of the motor vehicle, laden (and unladen in the case of M ₁

PR

=

maximum mass of an unbraked trailer which may be coupled, as declared by the motor vehicle manufacturer.

2.1.2. Secondary braking systems U.K.

2.1.2.1. The secondary braking system, even if the control which actuates it is also used for other braking functions, shall give a stopping distance not exceeding the following values and a mean fully developed deceleration not less than the following values: U.K.

category M ₁ :

(the second term corresponding to a mean fully developed deceleration of 2,9 m/s ² )

category M ₂ , M ₃ :

(the second term corresponding to a mean fully developed deceleration of 2,5 m/s ² )

category N:

(the second term corresponding to a mean fully developed deceleration of 2,2 m/s ² ).

2.1.2.2. If the secondary braking system control is a manual control, the prescribed performance shall be obtained by applying to the control a force not exceeding 400 N in the case of category M ₁ vehicles and 600 N in the case of other vehicles, and the control shall be so placed that it can be easily and quickly grasped by the driver. U.K.

2.1.2.3. If the secondary braking systems control is a foot control, the prescribed performance shall be obtained by applying to the control a force not exceeding 500 N in the case of category M ₁ vehicles and 700 N in the case of other vehicles, and the control shall be so placed that it can be easily and quickly actuated by the driver. U.K.

2.1.2.4. The performance of the secondary braking system shall be checked by the Type 0 test with the engine disconnected from the following initial speeds: U.K.

M 1 = 80 km/h	M 2 = 60 km/h	M 3 = 60 km/h
N 1 = 70 km/h	N 2 = 50 km/h	N 3 = 40 km/h

2.1.2.5. The secondary braking effectiveness test shall be conducted by simulating the actual failure conditions in the service braking system. U.K.

2.1.3. Parking braking systems U.K.

2.1.3.1. The parking braking system shall, even if it is combined with one of the other braking systems, be capable of holding a laden vehicle stationary on an 18 % up or down gradient. U.K.

2.1.3.2. On vehicles to which the coupling of a trailer is authorised, the parking braking system of the towing vehicle shall be capable of holding the combination of vehicles stationary on a 12 % gradient. U.K.

2.1.3.3. If the control is a manual control, the force applied to it shall not exceed 400 N in the case of category M ₁ vehicles and 600 N in the case of all other vehicles. U.K.

2.1.3.4. If it is a foot control, the force exerted on the control shall not exceed 500 N in the case of category M ₁ vehicles and 700 N in the case of all other vehicles. U.K.

2.1.3.5. A parking braking system which has to be actuated several times before attaining the prescribed performance shall be admissible. U.K.

2.1.3.6. To check compliance with the requirements of Annex I, point 2.2.1.2.4, a Type 0 test shall be carried out with the engine disconnected at the initial speed of 30 km/h. The mean fully developed deceleration on application of the control of the parking brake system and the deceleration immediately before the vehicle stops shall not be less than 1,5 m/s ² . The test shall be carried out with the laden vehicle. The force exerted on the braking control device shall not exceed the specified values. U.K.

2.1.4. Residual service braking performance after transmission failure U.K.

2.1.4.1. The residual performance of the service braking system, in the event of failure in a part of its transmission, shall give a stopping distance not exceeding the following values and a mean fully developed deceleration not less than the following values, using a control force not exceeding 700 N, when checked by the Type 0 test with the engine disconnected from the following initial speeds for the relevant vehicle category: U.K.

Stopping distance (m) and mean fully developed deceleration (m/s ² )

Type	km/h	Laden	m/s 2	Unladen	m/s 2
M 1	80		1,7		1,5
M 2	60		1,5		1,3
M 3	60		1,5		1,5
N 1	70		1,3		1,1
N 2	50		1,3		1,1
N 3	40		1,3		1,3

2.1.4.2. The residual braking effectiveness test shall be conducted by simulating the actual failure conditions in the service braking systems. U.K.

2.2. Vehicles of category O U.K.

2.2.1. Service braking systems U.K.

2.2.1.1. Requirement relating to tests of category O ₁ vehicles U.K.

2.2.1.1.1. Where the provision of a service braking system is mandatory, the performance of the system shall meet the requirements laid down for category O ₂ vehicles. U.K.

2.2.1.2. Requirements relating to tests of category O ₂ vehicles. U.K.

2.2.1.2.1. If the service braking system is of the continuous or semi-continuous type, the sum of the forces exerted at the periphery of the braked wheels shall be at least X % of the maximum stationary wheel load, X having the following values: U.K.

Full trailer, laden and unladen	50
Semi-trailer, laden and unladen	45
Centre-axle trailer, laden and unladen	50.

Where the trailer is fitted with a compressed-air braking system, the pressure in the control line shall not exceed 6,5 bar (1) and the pressure in the supply line shall not exceed 7,0 bar (1) during the brake test. The test speed is 60 km/h.

A supplementary test at 40 km/h must be carried out with the laden vehicle for comparison with the Type I test result.

2.2.1.2.2. Where the braking system is of the inertia type, it shall comply with the conditions laid down in Annex VIII. U.K.

2.2.1.2.3. In addition, these vehicles shall be subjected to the Type I test. U.K.

2.2.1.2.4. In the Type I test of a semi-trailer, the mass braked by its axle(s) shall correspond to the maximum axle load(s) (not including the king pin load). U.K.

2.2.1.3. Requirements relating to the testing of category O ₃ vehicles. U.K.

2.2.1.3.1. The same requirements apply as to category O ₂ vehicles. U.K.

2.2.1.4. Requirements relating to tests of category O ₄ vehicles. U.K.

2.2.1.4.1. If the service braking system is of the continuous or semi-continuous type, the sum of the forces exerted at the periphery of the braked wheels shall be equal to at least X % of the maximum stationary wheel load, X having the following values: U.K.

full trailer, laden and unladen	50
semi-trailer, laden and unladen	45
centre-axle trailer, laden and unladen	50.

Where the trailer is fitted with a compressed air braking system, the pressure in the control line shall not exceed 6,5 bar (1) and the pressure in the supply line shall not exceed 7,0 bar (1) during the brake test. The test speed is 60 km/h.

2.2.1.4.2. In addition, the vehicles shall undergo the Type-III test. U.K.

2.2.1.4.3. In the Type-III test of a semi-trailer, the mass braked by the latter's axle(s) shall correspond to the maximum axle load(s). U.K.

2.2.2. Parking braking systems U.K.

2.2.2.1. The parking braking system with which the trailer or semi-trailer is fitted shall be capable of holding the laden trailer or semi-trailer stationary, when separated from the towing vehicle, on an 18 % up or down gradient. The force applied to the control shall not exceed 600 N. U.K.

2.2.3. Automatic braking systems U.K.

2.2.3.1. The automatic braking performance in the event of a total pressure loss in the air supply line, when testing the laden vehicle from 40 km/h, shall not be less than 13,5 % of the maximum stationary wheel load. Wheel-locking at performance levels above 13,5 % is permitted. U.K.

2.3. Reaction time U.K.

Where a vehicle is fitted with a service braking system which is totally or partially dependent on a source of energy other than the muscular effort of the driver, the following requirements shall be satisfied:

2.3.1. In an emergency manoeuvre, the time elapsing between the moment when the control begins to be actuated and the moment when the braking force on the least favourably placed axle reaches the level corresponding to the prescribed performance shall not exceed 0,6 seconds. U.K.

2.3.2. In the case of vehicles fitted with compressed-air braking systems, the requirements of point 2.3.1 are considered to be satisfied if the vehicle complies with the provisions of Annex III. U.K.

2.3.3. In the case of vehicles fitted with hydraulic braking systems, the requirements of point 2.3.1 are considered to be satisfied if, in an emergency manoeuvre, the deceleration of the vehicle, or the pressure at the least favourable brake cylinder, reaches a level corresponding to the prescribed performance within 0,6 seconds. U.K.

Appendix (See point 1.1.4.2) Distribution of braking effort among vehicle axles

1. GENERAL REQUIREMENTS U.K.

Vehicles of categories M, N, O ₃ and O ₄ which are not equipped with an anti-lock system as defined in Annex X shall meet all the requirements of this Appendix. If a special device is used, this shall operate automatically. However, vehicles — other than those of category M ₁ — which are equipped with an anti-lock system as defined in Annex X, shall also meet the requirements of points 7 and 8 of this Appendix if they are in addition fitted with a special automatic device which controls the distribution of braking among the axles. In the event of failure of its control, it shall be possible to stop the vehicle as stipulated under points 6 of this Appendix.

2. SYMBOLS U.K.

i

=

axle index ( i = 1, front axle; i = 2, second axle; etc.)

P _i

=

normal reaction of road surface on axle i under static conditions

N _i

=

normal reaction of road surface on axle i under braking

T _i

=

force exerted by the brakes on axle i under normal braking conditions on the road

f _i

=

T _i /N _i -adhesion used by axle i (2)

J

=

deceleration of vehicle

g

=

acceleration due to gravity g = 10 m/s ²

z

=

braking rate of vehicle = J/g (3)

P

=

mass of vehicle

h

=

height above ground of centre of gravity specified by the manufacturer and agreed by the technical services conducting the approval test

E

=

wheelbase

k

=

theoretical coefficient of adhesion between tyre and road

K _c

=

correction factor — semi-trailer laden

K _v

=

correction factor — semi-trailer unladen

TM

=

sum of braking forces at the periphery of wheels of towing vehicles for trailers or semi-trailers

PM

=

total normal static reaction between road surface and wheels of towing vehicles for trailers or semi-trailers as referred to in points 3.1.4 and 3.1.5 respectively

P _m

=

pressure at coupling head of control line

TR

=

sum of braking forces at periphery of all wheels of trailer or semi-trailer

PR

=

total normal static reaction of road surface on wheels of trailer or semi-trailer

PR _max

=

value of PR at maximum mass of semi-trailer

E _R

=

distance between king-pin and centre of axle or axles of semi-trailer

h _R

=

height above ground of centre of gravity of semi-trailer specified by the manufacturer and agreed by the technical services conducting the approval test.

3. REQUIREMENTS FOR MOTOR VEHICLES U.K.

3.1. Two-axle vehicles U.K.

3.1.1. (4) For all categories of vehicles for k values between 0,2 and 0,8: U.K.

For all states of load of the vehicle, the adhesion curve of the front axle shall be situated above that of the rear axle:

• for all braking rates of between 0,15 and 0,8 in the case of vehicles of category M ₁ .

  However, for vehicles of this category over the range of z values between 0,3 and 0,45, an inversion of the adhesion utilisation curves is permitted provided that the adhesion utilisation curve of the rear axle does not exceed by more than 0,05 the line defined by the formula k = z (line of ideal adhesion utilisation — see diagram 1A),

• for all braking rates of between 0,15 and 0,5 in the case of vehicles of category N ₁ (5) .

  This condition is also considered satisfied if, for braking rates between 0,15 and 0,30, the adhesion utilisation curves for each axle are situated between two parallels to the line of ideal adhesion utilisation given by the equations k = z + 0,08 and k = z - 0,08 as shown in diagram 1C, where the adhesion utilisation curve for the rear axle may cross the line k = z - 0,08 and, for braking rates between 0,3 and 0,5, complies with the relation z ≥ k - 0,08 and between 0,5 and 0,61 with the relation z ≥ 0,5 k + 0,21,

• for all braking rates of between 0,15 and 0,30 in the case of other categories. This condition is also considered satisfied if, for braking rates between 0,15 and 0,30 the adhesion utilisation curves for each axle are situated between two parallels to the line of ideal adhesion utilisation given by the equations k = z + 0,08 and k = z - 0,08 as shown in diagram 1B, and the adhesion utilisation curve for the ear axle, for braking rates z ≥ 0,3 complies with the relation:

  

3.1.2. In the case of a motor vehicle authorised to tow trailers of category O ₃ or O ₄ fitted with compressed-air braking systems: U.K.

3.1.2.1. When tested with the energy source stopped, the supply line blocked off and a reservoir of 0,5 litre capacity connected to the control line, and the system at cut-in and cut-out pressures, the pressure at full application of the service braking system control shall be between 6,5 and 8,5 bar at the coupling heads of the supply line and the control line, irrespective of the load condition of the vehicle. These pressures shall be demonstrably present in the towing vehicle when uncoupled from the trailer. The compatibility bands in diagrams 2, 3 and 4A of this Appendix to Annex II shall not be extended beyond 7,5 bar. U.K.

3.1.2.2. It shall be ensured that at the coupling head of the supply line a pressure of at least 7 bar is available when the system is at cut-in pressure; this pressure shall be demonstrated without applying the service braking system. U.K.

3.1.3. Verification of the requirements of point 3.1.1 U.K.

In order to verify the requirement of point 3.1.1, the manufacturer shall provide the adhesion utilisation curves for the front and rear axles calculated by the formulae:

;

.

The graphs shall be plotted for both the following load conditions:

• Unladen, in running order with the driver on board.

  In the case of a vehicle presented as a bare chassis-cab, a supplementary load may be added to simulate the mass of the body, not exceeding the minimum mass declared by the manufacturer in Annex XVIII.

• Laden.

  Where provision is made for several possibilities of load distribution, the one whereby the front axle is the most heavily laden shall be the one to be taken into consideration.

3.1.4. Towing vehicles other than tractive units for semi-trailers U.K.

3.1.4.1. In the case of a motor vehicle authorised to tow trailers of category O ₃ or O ₄ fitted with compressed-air braking systems, the permissible relationship between the braking rate U.K.

and the pressure p _m shall be within the areas shown in diagram 2.

3.1.5. Tractive units for semi-trailers U.K.

3.1.5.1. Tractive units with unladen semi-trailer U.K.

An unladen articulated combination is considered to be a tractive unit in running order, with the driver on board, coupled to an unladen semi-trailer. The dynamic load of the semi-trailer on the tractive unit shall be represented by a static mass, mounted at the location of the king pin of the fifth wheel coupling, equal to 15 % of the maximum mass on the coupling. The braking forces shall continue to be regulated between the state of the tractive unit with semi-trailer (unladen) and that of the tractive unit alone, (without semi-trailer); the braking forces relating to the tractive unit alone shall be verified.

3.1.5.2. Tractive units with laden semi-trailer U.K.

A laden articulated combination shall be considered to be a tractive unit in running order with the driver on board coupled to a laden semi-trailer. The dynamic load of the semi-trailer on the tractive unit shall be represented by a static mass P _s , mounted at the location of the king pin of the fifth wheel coupling, equal to:

where P _so represents the difference between the maximum laden mass of the tractive unit and its unladen mass.

For h the following value shall be taken:

where:

• h ₀ is the height of the centre of gravity of the tractive unit

• h _s is the height of the coupling on which the semi-trailer rests

• P ₀ is the unladen mass of the solo tractive unit

  

3.1.5.3. In the case of a vehicle fitted with a compressed-air braking system, the permissible relationship between the braking rate U.K.

and the pressure p _m shall be within the areas shown in diagram 3.

3.2. Vehicles with more than two axles U.K.

The requirements of point 3.1 shall apply to vehicles with more than two axles. The requirements of point 3.1.1 with respect to wheel-lock sequence shall be considered to be met, if in the case of braking rates of between 0,15 and 0,30, the adhesion used by at least one of the front axles shall be greater than that used by at least one of the rear axles.

4. REQUIREMENTS FOR SEMI-TRAILERS U.K.

4.1. For semi-trailers fitted with compressed-air braking systems U.K.

The permissible relationship between the braking rate

and the pressure p _m shall lie within two areas derived from diagrams 4A and 4B for the laden and unladen states of load. This requirement shall be met for all permissible load conditions of the semi-trailer axles.

4.2. If the requirements of point 4.1 cannot be satisfied in conjunction with the requirements of point 2.2.1.2.1 of Annex II for semi-trailers with a K _c factor less than 0,8 then the semi-trailer shall meet the minimum braking performance specified in point 2.2.1.2.1 of Annex II and be fitted with an anti-lock system complying with Annex X, except the compatibility requirement in point 1 of that Annex. U.K.

5. REQUIREMENTS FOR FULL AND CENTRE-AXLE TRAILERS U.K.

5.1. For full trailers fitted with compressed-air braking systems: U.K.

5.1.1. The requirements set out in point 3.1 shall apply to twin axle trailers (except where the axle spread is less than two metres). U.K.

5.1.2. Full trailers with more than two axles shall be subject to the requirements contained in point 3.2. U.K.

5.1.3. The permissible relationship between the braking rate U.K.

and the pressure p _m shall lie within the designated areas in diagram 2 for the laden and unladen states of load.

5.2. For centre-axle trailers fitted with compressed-air braking systems: U.K.

5.2.1. the permissible relationship between the braking rate U.K.

and the pressure p _m shall lie within two areas derived from diagram 2, by multiplying the vertical scale by 0,95, for the laden and unladen states of load.

5.2.2. If the requirements of point 2.2.1.2.1 of Annex II cannot be satisfied due to lack of adhesion, then the centre-axle trailer shall be fitted with an anti-lock system complying with Annex X. U.K.

6. CONDITIONS TO BE FULFILLED IN THE CASE OF FAILURE OF THE BRAKING DISTRIBUTION SYSTEM U.K.

When the requirements of this Appendix are fulfilled by means of a special device (e. g. controlled mechanically by the suspension of the vehicle), it shall be possible, in the event of the failure of this device or its means of control, to stop the vehicle under the conditions specified for secondary braking in the case of motor vehicles; for those vehicles authorised to tow a trailer fitted with air brakes, it shall be possible to achieve a pressure at the coupling head of the control line within the range specified in point 3.1.2 of this Appendix. In the event of failure of the means of controlling the device in trailers and semi-trailers, a braking rate of at least 30 % of the service braking system performance prescribed for the vehicle in question shall be attained.

7. MARKINGS U.K.

7.1. Vehicles, other than those of category M ₁ , which meet the requirements of this Appendix by means of a device mechanically controlled by the suspension of the vehicle, shall be marked to show the useful travel of the device between the positions corresponding to vehicle unladen and laden states respectively and any further information to enable the setting of the device to be checked. U.K.

7.1.1. When a load sensing device is controlled via the suspension of the vehicle by any other means, the vehicle shall be marked with information to enable the setting of the device to be checked. U.K.

7.2. When the requirements of this Appendix are met by means of a device which modulates the air pressure in the brake transmission, the vehicle shall be marked to show the axle loads at the ground, the nominal outlet pressures of the device and an inlet pressure of not less than 80 % of the maximum design inlet pressure, as declared by the vehicle manufacturer, for the following states of load: U.K.

7.2.1. Technically permissible maximum axle load for the axle(s) which control(s) the device. U.K.

7.2.2. Axle load(s) corresponding to the mass of the vehicle in running order as defined in point 2.6 of Annex I to Directive 70/156/EEC. U.K.

7.2.3. The axle load(s) approximating to the vehicle with proposed bodywork in running order where the axle load(s) mentioned in point 7.2.2 relate(s) to the vehicle chassis with cab. U.K.

7.2.4. The axle load(s) designated by the manufacturer to enable the setting of the device to be checked in service if this is (these are) different from the loads specified in points 7.2.1, 7.2.2 and 7.2.3. U.K.

7.3. Point 1.7.2 of the addendum to the type-approval certificate (Appendix 1 of Annex IX) shall include information to enable compliance with the requirements of points 7.1 and 7.2 to be checked. U.K.

7.4. The markings referred to under points 7.1 and 7.2 shall be affixed in a visible position in indelible form. An example of the markings for a mechanically controlled device in a vehicle fitted with compressed-air braking is shown in diagram 5. U.K.

8. PRESSURE TEST CONNECTIONS U.K.

8.1. Braking systems incorporating the devices referred to in point 7.2 shall be fitted with pressure test connections in the pressure line upstream and downstream of the device, at the closest readily accessible positions. The downstream connection shall not be required if the pressure at that point can be checked at the connection required by point 4.1 of Annex III. U.K.

8.2. The pressure test connections shall comply with clause 4 of ISO standard 3583-1984. U.K.

9. VEHICLE INSPECTION U.K.

During the EC type-approval testing of a vehicle the technical inspection authority shall verify conformity with the requirements contained in the present Appendix and carry out any further tests considered necessary to this end. The report on the additional tests shall be appended to the EC type-approval certificate.

Diagram 1A U.K. Vehicles of category M ₁ and certain vehicles of category N ₁ from 1 October 1990 U.K. (see point 3.1.1) U.K.

Diagram 1B U.K. Motor vehicles (other than those of categories M ₁ and N ₁ and full trailers U.K. (see point 3.1.1) U.K.

NB: U.K.

The lower limit of the corridor is not applicable for the adhesion utilisation of the rear axle. U.K.

Diagram 1C U.K. Vehicles of category N ₁ (with certain exceptions from 1 October 1990) U.K. (see point 3.1.1) U.K.

NB: U.K.

The lower limit of the corridor is not applicable for the adhesion utilisation of the rear axle U.K.

Diagram 2 U.K. Towing vehicles and trailers U.K. (see points 3.1.4 and 5) U.K.

NB: U.K.

1. It is understood that, between the values and U.K.

or and

it is not necessary that there should be proportionality between the braking rate or

and the control line pressure as measured at the coupling head.

2. The relationships required by the diagram apply progressively for intermediate states of loading between the laden and the unladen states and shall be achieved by automatic means. U.K.

Diagram 3 U.K. Tractive units for semi-trailers U.K. (see point 3.1.5) U.K.

NB: U.K.

1. It is understood that, between the values and U.K.

it is not necessary that there should be proportionality between the braking rate

and the control line pressure as measured at the coupling head.

2. The relationships required by the diagram apply progressively for intermediate states of loading between the laden and the unladen states and shall be achieved by automatic means. U.K.

Diagram 4A U.K. Semi-trailers U.K. (see point 4) U.K.

NB: U.K.

1. It is understood that, between the values and U.K.

it is not necessary that there should be proportionality between braking rate

and the control line pressure as measured at the coupling head.

2. The relationship between the braking rate U.K.

and control line pressure for the laden and unladen condition is determined as follows:

The factors K _c (laden), K _v (unladen) are obtained by reference to diagram 4B. Contruct the laden und unladen bands by multiplying the upper and lower boundaries of the band in diagram 4A shown above by the two factors obtained, K _c and K _v respectively.

Diagram 4B (see point 4) U.K.

Explanatory note on the use of diagram 4B U.K.

1. Formula from which diagram 4B is derived is: U.K.

2. Description of the method of use by means of a worked example. U.K.

2.1 The dashed lines shown on diagram 4B refer to the determination of the factors K _c and K _v for the following vehicle where: U.K.

	Laden	Unladen
P	24 tonnes	4,2 tonnes
PR	15 tonnes	3 tonnes
PR max	15 tonnes	15 tonnes
h R	1,8 m	1,4 m
E R	6,0 m	6,0 m

In the following items the figures in parenthesis relate only to the vehicle being used for the purpose if illustrating the method of use of Diagram 4B.

2.2 Calculate the ratios: U.K.

(a)	laden	(= 1,6)
(b)	unladen	(= 1,4)
(c)	unladen	(= 0,2)

2.3. Determination of the laden factor K _c : U.K.

(a)

Start at appropriate h _R (h _R = 1,8 m).

(b)

Move horizontally to the appropriate gP/PR line (gP/PR = 1,6).

(c)

Move vertically to appropriate E _R line (E _R = 6,0 m).

(d)

Move horizontally to K _c scale, K _c is the laden factor required (K _c = 1,04).

2.4. Determination of the unladen factor K _v : U.K.

2.4.1. Determination of the factor K ₂ U.K.

(a)

Start at appropriate h _R (h _R = 1,4 m).

(b)

Move horizontally to appropriatePR/PR _max line in group of curves nearest to vertical axis (PR/PR _max = 0,2).

(c)

Move vertically to horizontal axis and read off the value of K ₂ (K ₂ = 0,13 m).

2.4.2. Determination of factor K ₁ U.K.

(a)

Start at appropriate h _R (h _R = 1,4 m).

(b)

Move horizontally to the appropriate gP/PR line (gP/PR = 1,4).

(c)

Move vertically to the appropriate E _R line (E _R = 6,0 m).

(d)

Move horizontally to the appropriate PR/PR _max line in group of curves furthest from the vertical axis (PR/PR _max = 0,2).

(e)

Move vertically to horizontal axis and read off the value of K ₁ (K ₁ = 1,79).

2.4.3. Determination of factor K _v U.K.

The unladen factor K _v is obtained from the following expression:

.

Diagram 5 U.K. Load sensing device U.K. (see point 7.4) U.K.

]

(1)

[F1 The pressures specified here and in the following Annexes are relative pressures measured in bars.

(2)

Adhesion curves used by each axle means curves showing the adhesion used by axle I plotted against the vehicle braking rate under specified load conditions.

(3)

For semi-trailers, z is the braking force divided by the static mass on the semi-trailer axle(s).

(4)

The provisions of point 3.1.1 do not affect the requirements of Annex II relating to the braking efficiency. However, if, when verifying the provisions of point 3.1.1 braking efficiencies are obtained which are higher than those prescribed in Annex II, the provisions relating to the adhesion utilisation curve shall be applied within the areas of diagrams IA and IB defined by the straight lines k = 0,8 and z = 0,8.

(5)

Vehicles of category N ₁ with a laden/unladen rear axle loading ratio not exceeding 1,5 or having a maximum mass of less than 2 tonnes will have to comply with the requirements for category M ₁ vehicles of this point from 1 October 1990.]

Textual Amendments

F1 Substituted by Commission Directive 98/12/EC of 27 January 1998 adapting to technical progress Council Directive 71/320/EEC on the approximation of the laws of the Member States relating to the braking devices of certain categories of motor vehicles and their trailers (Text with EEA relevance).