Document ID: chunk:federal_register_of_legislation:F2021C01192:body:0:p38
Version: federal_register_of_legislation:F2021C01192
Segment Type: other
Provision Reference: 
Character Range: 102115–104976

normal braking conditions on the road
                     fi = Ti/Ni , adhesion utilized by axle i [13]
                     J = deceleration of the vehicle
                     g = acceleration due to gravity : g = 9.81 m/s2
                     z = braking rate of vehicle = J/g
                     P = mass of vehicle
                     h = height 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
3.  Requirements
3.1.(A)  For all states of load of the vehicle, the adhesion utilization curve of the rear axle shall not be situated above that for the front axle:[14]
 for all braking rates between 0.15 and 0.8:
3.1.(B)  For k values between 0.2 and 0.82:
 z  0.1 + 0.7 (k - 0.2) (see diagram 1 of this annex)
3.2.  In order to verify the requirements of paragraph 3.1. of this annex, the manufacturer shall provide the adhesion utilization curves for the front and rear axles calculated by the formulae:

 The curves shall be plotted for both the following load conditions:
3.2.1.  unladen, in running order with the driver on board;
3.2.2.  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 considered;
3.2.3.  for vehicles fitted with an electric regenerative braking system of category B, where the electric regenerative braking capacity is influenced by the electric state of charge, the curves shall be plotted by taking account of the electric braking component under the minimal and maximum conditions of delivered braking force. This requirement is not applicable if the vehicle is equipped with an anti-lock device which controls the wheels connected to the electric braking then the requirements of Annex 6 to this Regulation shall apply.
4.  Requirements to be met in case of failure of the braking distribution system
 When the requirements of this annex 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 its control, (e.g. by disconnecting the control linkage), to stop the vehicle under the conditions of the Type-0 test with the engine disconnected to give a stopping distance not exceeding
0.1 v + 0.0100 v2 (m) and a mean fully developed deceleration not less than 3.86 m/s2.
5.  Vehicle testing
 During the type-approval testing of a vehicle, the technical inspection authority shall verify conformity with the requirements contained in the present annex, by carrying out the following tests:
5.1. Wheel-lock sequence test (see Appendix 1)
 If the wheel-lock sequence test confirms that the front wheels lock before or simultaneously