Document ID: chunk:federal_register_of_legislation:F2021C01192:body:0:p48
Version: federal_register_of_legislation:F2021C01192
Segment Type: other
Provision Reference: 
Character Range: 127261–130084

quotient of the maximum braking rate with the anti-lock system operative (zAL) and the coefficient of adhesion (k)

i         the  - value measured on axle i (in the case of a motor vehicle with a category 3 anti-lock system)

H         the  - value on the high-adhesion surface

L         the  - value on the low-adhesion surface

F          force ( N )

Fdyn       normal reaction of road surface under dynamic conditions with the anti-lock system operative

Fidyn      Fdyn on axle i in case of power-driven vehicles

Fi         normal reaction of road surface on axle i under static conditions

FM         total normal static reaction of road surface on all wheels of power-driven vehicle

FMnd[24]   total normal static reaction of road surface on the unbraked and non-driven axles of the power-driven vehicle

FMd1       total normal static reaction of road surface on the unbraked and driven axles of the power-driven vehicle

FWM1       0.01 FMnd + 0.015 FMd

g          acceleration due to gravity (9.81 m/s2)

h          height of centre of gravity specified by the manufacturer and agreed by the Technical Service conducting the approval test

k          coefficient of adhesion between tyre and road

kf         k - factor of one front axle

kH         k - value determined on the high-adhesion surface

ki         k - value determined on axle i for a vehicle with a category 3 anti-lock system

kL         k - value determined on the low-adhesion surface

klock      value of adhesion for 100 per cent slip

kM         k - factor of the power-driven vehicle

kpeak      maximum value of the curve "adhesion versus slip"

kr         k - factor of one rear axle

P          mass of individual vehicle (kg)

R          ratio of kpeak to klock

t          time interval (s)

tm         mean value of  t

tmin       minimum value of  t

z          braking rate

zAL        braking rate z of the vehicle with the anti-lock system operative

zm         mean braking rate

zmax       maximum value of  z

zMALS      zAL of the power-driven vehicle on a "split surface"

Annex 6 - Appendix 2
  Utilisation of adhesion
1.  Method of measurement
1.1.  Determination of the coefficient of adhesion (k)
1.1.1.  The coefficient of adhesion (k) shall be determined as the quotient of the maximum braking forces without locking the wheels and the corresponding dynamic load on the axle being brakes.
1.1.2.  The brakes shall be applied on only one axle of the vehicle under test, at an initial speed of 50 km/h. The braking forces shall be distributed between the wheels of the axle to reach maximum performance. The anti-lock system shall be disconnected, or inoperative, between 40 km/h and 20 km/h.
1.1.3.  A number of tests at increments of line pressure shall be carried out to determine the maximum braking rate