Appendix (See 1.1.4.2):

DISTRIBUTION OF BRAKING EFFORT AMONG VEHICLE AXLES 1. GENERAL REQUIREMENTS Vehicles of categories M1, M2, M3, N1, N2, N3, O3 and O4 which are not fitted with a wheel anti-locking device shall fulfil the conditions of the present Appendix. 2. NOTATION i = axle index (i = 1, front axle; i = 2, rear axle). Pi = normal reaction of road surface on axle i under static conditions. Ni = normal reaction of road surface on axle i under braking. Ti = force exerted by the brakes on axle i. fi = Ti/Ni adhesion used by axle i. J = deceleration of vehicle. g = acceleration of gravity = 10 m/s2. z = braking ratio of vehicle = J/g ( 5 ) P = ►M2 mass ◄ of vehicle. h = height of centre of gravity. E = wheelbase. k = theoretical coefficient of adhesion between tyre and road. Adhesion curves used by the vehicle means curves showing the adhesion used by the front axle and the rear axle plotted against the vehicle braking ratio on the specified load conditions. 3. REQUIREMENTS FOR MOTOR VEHICLES 3.1. Two axle vehicles 3.1.1. ( 6 ) Under all load conditions of the vehicle the adhesion curve for the front wheels shall be above that for the rear wheels: — for all braking ratios of between 0·15 and 0·8 in the case of vehicles of category M1; — for braking ratios of between 0·15 and 0·30 in the case of vehicles of other categories, with the exeption of urban buses. In addition, for k values of between 0·2 and 0·8, 3.1.2. The above conditions shall be fulfilled automatically. 3.1.3. The pressure at the coupling head of a motor vehicle authorized to draw a trailer fitted with air brakes shall not be affected by the operation of the pressure-regulating devices on the axles of the drawing vehicle. 3.1.4. In order to verify the requirement of item 3.1.1., the manufacturer shall provide the adhesion utilization curves for the front and rear axles calculated by the formulas:



f1 = T1N1 = T1P1 + z hE P f2 = T2N2 = T2P2 − z hE P 3.1.4.1. Vehicles other than tractive units for semi-trailers. The graphs shall be plotted for both the following load conditions: — unladen, in running order with the driver on board, — 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. The values specified by the manufacturer shall be taken for h. 3.1.4.2. Tractive units for semi-trailers. 3.1.4.2.1. Solotractive units. The graphs shall be plotted for an unladen vehicle in running order with the driver on board and h shall be taken as the value specified by the manufacturer. 3.1.4.2.2. Laden tractive units. The dynamic load of the semi-trailer on the tractive unit shall be represented by a static ►M2 mass ◄ Ps applied to the coupling kingpin, equal to: Ps = Pso1 + 0·45 z where Pso represents the difference between the maximum laden ►M2 mass ◄ of the tractive unit and its unladen ►M2 mass ◄ . For h the following value shall be taken hoPo + hsPsP where — ho is the value specified in item 3.1.4.2.1, — hs is the height of the plane of the coupling on which the semi-trailer rests. — Po is the unladen ►M2 mass ◄ of the solotractive unit, — P = Po + Ps. 3.2. Vehicles with more than two axles The requirements of Item 3.1. shall apply to vehicles with more than two axles. These requirements shall be considered to be met, if, in the case of braking ratios between 0·15 — 0·30, the adhesion used by the front axle is greater than that used by at least one of the rear axles. 4. REQUIREMENTS FOR SEMI-TRAILERS 4.1. The following requirements shall only apply to semi-trailers fitted with compressed air brakes. 4.2. The braking systems fitted to these semi-trailers shall be such that the curve representing the braking ratio of the semi-trailer's axles plotted against the service line pressure measured at the coupling head within the hatched area of the attached diagram. 4.3. This requirement shall be met for all permissible load conditions of the semi-trailer axles. 5. REQUIREMENTS FOR TRAILERS 5.1. The following requirements shall only apply to trailers fitted with air brakes. They shall not apply to single-axle trailers nor to twin-axle trailers where the axle spread is less than 2 metres. 5.2. The requirements set out in item 3.1 shall apply to twin-axle trailers not excluded by the requirements contained in 5.1. 5.3. Trailers with more than two axles shall be subject to the requirements contained in item 3.2. 6. CONDITIONS TO BE FULFILLED IN THE CASE OF FAILURE OF THE BRAKING DISTRIBUTION SYSTEM When the requirements of this Appendix are met by means of a special device (e.g., controlled mechanically by the suspension of the vehicle), it shall be possible in the case of failure of this device or its control unit to stop the vehicle under the conditions prescribed for emergency braking. 7. MARKINGS 7.1. Vehicles, other than those of category M1, 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. 7.2. When the requirements of this Appendix are met by means of a device actuated by compressed air, the vehicle shall be marked to show the pressure values at the outlet side of the device during full braking of the vehicle under both unladen and laden conditions. 7.3. The markings referred to under items 7.1 and 7.2 above shall be affixed in a visible position in indelible form. 8. VEHICLE INSPECTION During the EEC 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 EEC type-approval certificate. Diagram (See item 4.2 of the Appendix)