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States relating to the braking devices of certain categories of motor vehicles and of their trailers (71/320/EEC) (repealed)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 6. SPECIAL PROVISIONS CONCERNING TRAILERS U.K.

6.1. Energy consumption U.K.

Trailers equipped with anti-lock braking systems shall be so designed that, even after the service braking control device has been fully applied for some time, the vehicle retains sufficient energy to bring it to a halt within a reasonable distance.

6.1.1. Compliance with the above requirement shall be checked by the procedure specified below, with the vehicle unladen, on a straight and level road with a surface having a good coefficient of adhesion (1) , and with the brakes adjusted as closely as possible and with the brake load sensing device (if fitted) held in the ‘laden’ position throughout the test. U.K.

6.1.2. In the case of compressed-air braking systems, the initial energy level in the energy storage device(s) shall be equivalent to a pressure of 8,0 bar at the coupling head of the trailer's supply line. U.K.

6.1.3. With an initial vehicle speed of at least 30 km/h, the brakes shall be fully applied for a time t = 15 s, during which time the energy consumed by the indirectly controlled wheels shall be taken into consideration and all directly controlled wheels shall remain under control of the anti-lock braking system. During this test, the supply to the energy storage device(s) shall be cut off. U.K.

If the time t = 15 s cannot be completed in a single braking phase, further phases may be used. During these phases, no fresh energy shall be supplied to the energy storage device(s) and, as from the second phase, the additional energy consumption for filling the actuators is to be taken into account, e.g. by the following test procedure.

The pressure in the reservoir(s) when starting the first phase is to be that stated in point 6.1.2 above. At the beginning of the following phase(s), the pressure in the reservoir(s) after application of the brakes shall be not less than the pressure in the reservoir(s) at the end of the preceding phase. At the subsequent phase(s), the only time to be taken into account is from the point at which the pressure in the reservoir(s) is equal to that at the end of the preceding phase.

6.1.4. At the end of the braking, with the vehicle stationary, the service braking control device shall be fully actuated four times. During the fifth application, the pressure in the operating circuits shall be sufficient to provide a total braking force at the periphery of the wheels equal to not less than 22,5 % of the maximum stationary wheel load and without causing and automatic application of any braking system not being under the control of the anti-lock braking system. U.K.

6.2. Utilisation of adhesion U.K.

6.2.1. Trailers equipped with an anti-lock braking system shall be deemed acceptable when the condition ε ≥ 0,75 is satisfied, where ε represents the adhesion utilised, as defined in point 2 of Appendix 2 to this Annex. This condition shall be verified with the vehicle unladen, on a straight and level road with a surface having a good coefficient of adhesion (2) (3) . U.K.

6.2.2. To eliminate the effects of differential brake temperatures, it is recommended that Z _RAL be determined prior to the determination of k _R . U.K.

6.3. Additional checks U.K.

6.3.1. At speeds exceeding 15 km/h, the wheels directly controlled by an anti-lock braking system shall not lock when the full force (4) is suddenly applied on the control device of the towing vehicle. This shall be checked, under the conditions prescribed in point 6.2 of this Annex, at initial speeds of 40 km/h and 80 km/h. U.K.

6.3.2. The provisions of this point shall only apply to trailers equipped with an anti-lock braking system of category A. U.K.

When the right and left wheels are situated on surfaces which produce differing maximum braking rates (Z _RALH and Z _RALL ), where

and

the directly controlled wheels shall not lock when the full force (5) is suddenly applied on the control device of the towing vehicle at a speed of 50 km/h. The ratio z _RALH /z _RALL may be ascertained by the procedure in point 2 of Appendix 2 to this Annex or by calculating the ratio z _RALH /z _RALL . Under this condition, the unladen vehicle shall satisfy the prescribed braking rate in Appendix 3 of this Annex (6) .

6.3.3. At vehicle speeds ≥ 15 km/h, the directly controlled wheels are permitted to lock for brief periods, but a speeds < 15 km/h, any locking is permissible. Indirectly controlled wheels are permitted to lock at any speed. In all cases, stability must not be affected.] U.K.

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)

[F1 If the coefficient of adhesion of the test track is too high, preventing the anti-lock braking system from cycling then the test may be carried out on a surface with a lower coefficient of adhesion.

(2)

If the coefficient of adhesion of the test track is too high, preventing the anti-lock braking system from cycling then the test may be carried out on a surface with a lower coefficient of adhesion.

(3)

In the case of trailers fitted with a brake load sensing device the pressure setting may be increased to ensure full cycling.

(4)

‘ Full force ’ means the maximum force laid down in Annex II for the category of vehicle: a higher force may be used if required to activate the anti-lock braking system.

(5)

‘ Full force ’ means the maximum force laid down in Annex II for the category of vehicle: a higher force may be used if required to activate the anti-lock braking system.

(6)

In the case of trailers fitted with a brake load sensing device the pressure setting may be increased to ensure full cycling.]

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).