Document ID: chunk:federal_register_of_legislation:F2021C01192:body:0:p46
Version: federal_register_of_legislation:F2021C01192
Segment Type: other
Provision Reference: 
Character Range: 122396–125042

The utilization of adhesion by the anti-lock system takes into account the actual increase in braking distance beyond the theoretical minimum. The anti-lock system shall be deemed to be satisfactory when the condition ε ≥ 0.75 is satisfied, where ε represents the adhesion utilized, as defined in paragraph 1.2. of Appendix 2 to this annex.
5.2.2.  The adhesion utilization  shall be measured on road surfaces with a coefficient of adhesion of 0.36 or less, and of about 0.8 (dry road), with an initial speed of 50 km/h. To eliminate the effects of differential brake temperatures it is recommended that zAL be determined prior to the determination of k.
5.2.3.  The test procedure to determine the coefficient of adhesion (k) and the formulae for calculation of the adhesion utilization () shall be those laid down in Appendix 2 to this annex.
5.2.4.  The utilization of adhesion by the anti-lock system shall be checked on complete vehicles equipped with anti-lock systems of categories 1 or 2. In the case of vehicles equipped with category 3 anti-lock systems, only the axle(s) with at least one directly controlled wheel shall satisfy this requirement.
5.2.5.  The condition   0.75 shall be checked with the vehicle both laden and unladen.[20]
  The laden test on the high adhesion surface may be omitted if the prescribed force on the control device does not achieve full cycling of the anti-lock system.
  For the unladen test, the control force may be increased up to 100 daN if no cycling is achieved with its full force value.[21] If 100 daN is insufficient to make the system cycle, then this test may be omitted.
5.3.  Additional checks
  The following additional checks shall be carried out with the engine disconnected, with the vehicle laden and unladen:
5.3.1.  The wheels directly controlled by an anti-lock system shall not lock when the full force8 is suddenly applied on the control device, on the road surfaces specified in paragraph 5.2.2. of this annex, at an initial speed of v = 40 km/h and at a high initial speed v = 0.8 vmax   120 km/h;[22]
5.3.2.  When an axle passes from a high-adhesion surface (kH) to a low-adhesion surface (kL), where kH  0.5 and kH / kL  2,[23]  with the full force8 applied on the control device, the directly controlled wheels shall not lock. The running speed and the instant of applying the brakes shall be so calculated that, with the anti-lock system fully cycling on the high-adhesion surface, the passage from one surface to the other is made at high and at low speed, under the conditions laid down in paragraph 5.3.1.;9
5.3.3.  When a vehicle passes from a low-adhesion surface