Document ID: chunk:federal_register_of_legislation:F2007C00493:front:0:p14
Version: federal_register_of_legislation:F2007C00493
Segment Type: other
Provision Reference: 
Character Range: 39157–42286

gravity.
17.2.2.                          No friction utilisation factor (F) must exceed 0.7 at z = 0.45 (a friction utilisation factor of greater than 0.7 is taken as to mean that wheel lock would have occurred in the physical test otherwise required by part 11.
17.3.                                The 'Established Retardation Coefficient' of the trailer must be calculated using the formula in clause 17.3.2 at levels of input 'Control Signal' starting no higher than 0.2 'E' and increasing in increments of not more than 0.2 'E' until an 'Established Retardation Coefficient' of not less than 0.45 is achieved.
17.3.1.                          All calculated 'Established Retardation Coefficient' values must lie between the upper and lower boundaries of Figure 1 .

17.3.2.
The 'Established Retardation Coefficient' must be calculated by

         where :

              e is the value of 'E'
              C is the ratio of output Signal Level to 'Control Signal' strength for the 'Control System' for the 'Axle' concerned
              T  is the 'Brakes' output torque per unit input signal to the 'Brakes' actuator from output of the 'Control System' for the 'Axle' concerned.
              R  is the rolling radius of the tyre on the wheel
              P is the static load on the 'Axle' concerned
              1,2,etc are subscripts referring to the concerned 'Axle'.
18.                                      SERVICE BRAKE FADE CALCULATION
18.1.                                The 'Service Brake System' will be considered to have sufficient brake fade resistance to meet the requirements of this rule if the 'Gross Axle Load Rating' of each 'Foundation Brake' rated according to the fade test in clause 22.3.6 is greater than the 'Gross Trailer Mass' multiplied by the percentage of total brake torque provided by that 'Foundation Brake' for at least one 'Control Signal' level necessary to produce a calculated 'Established Retardation Coefficient' of not less than 0.45 under the Service Brake test Conditions described in part 11 without prior fade conditioning stops.
19.                                      EMERGENCY BRAKE SYSTEM CALCULATION.
19.1.                                The 'Established Retardation Coefficient' for the 'Emergency Brake System' must be determined by computing the total braking force (kN) at the wheels to which emergency brakes are fitted and dividing by [9.81  'Gross Trailer Mass' (tonnes)].
19.2.                                The braking force at each 'Axle' must be calculated according to

         where:

         F is the tangential force at the braked wheels on the 'Axle' concerned
         A is the input to the emergency brakes actuator in units of 'E'
         T is the 'Brakes' output torque per 1.0 'E' for the 'Emergency Brake System'
         R is the rolling radius of the tyre fitted to the wheel.
19.2.1.                          Where the actuating force is dependent on the stroke, as in the case of spring brakes, the value of A used in the equation above must be that corresponding to the 'Brakes' actuator stroke achieved by the 'Emergency Brake System'