Document ID: chunk:federal_register_of_legislation:F2006L03060:body:0:p16
Version: federal_register_of_legislation:F2006L03060
Segment Type: other
Provision Reference: 
Character Range: 43599–46536

The brake control valve control shall be designed so that the manner of its operation shall have no effect on the output response of the test rig. The brake control valve may be arranged to provide a modulated test rig output signal for other brake development purposes but which for the purpose of measuring trailer 'Brake System' response in accordance with clause 38.3.11.3 will be rendered inoperative.

38.4.                                PERFORMANCE CALCULATION REQUIREMENTS

38.4.1.                          Service Brake Effectiveness Calculation

38.4.1.1.                    Service Brake Effectiveness will be considered satisfactory if it complies with all the requirements of clause 38.4.1.

38.4.1.2.                    The distribution of braking effort amongst the 'Axle's' in an 'Axle Group' shall be a value, or be in the range of values, referred to in clause 38.4.6.3.4 (suspension behaviour).

38.4.1.3.                    In the case of 'Dog Trailers' at least one front 'Axle' shall have a higher friction utilisation than that of at least one rear 'Axle' at decelerations greater than:

(a)  0.3 g in the case of 2 'Axle' 'Dog Trailers',

(b)  0.15 g in the case of 'Dog Trailers' with 3 or more 'Axle's'.

38.4.1.3.1.              In the case of two-'Axle' 'Dog Trailers' the friction utilisation factors may be calculated according to
Friction Utilization Factor = Tangential Force at Wheel
   Dynamic Load at Wheel
so:

and:

F  Friction utilisation factor.

P1  front 'Axle' static load

P2  rear 'Axle' static load

P  total static 'Axle' Load

h  height of trailer and load centre of mass

L  'Wheel Base

z  deceleration, as a proportion of acceleration due to gravity.

38.4.1.3.2.              No friction utilisation factor (F) shall exceed 0.7 at z = 0.45.

This is taken as to mean that wheel lock would have occurred in the physical test otherwise required by clause 38.3.3.2.2 (service brake effectiveness).

38.4.1.3.3.              For 'Dog Trailers' with more than two 'Axle's' where it is not practical to calculate the friction utilisation factors, a skid test on a loose surface at 'LTM' to ensure that at least one front 'Axle' skids before a rear 'Axle' is sufficient evidence.
38.4.1.4.                    The braking ratio      (Total brake force)
     ('Total Trailer Axle Load')

of the trailer for various levels of input 'Control Signal' as determined on the basis of data provided under clause 38.4.6.1 for the 'Control System' and clause 38.4.6.2 for the 'Foundation Brakes', shall lie between the upper and lower bounds of Figure 1. e.g.
  e (C1T1 + C2T2 + … etc
     total brake force at e   =        R          R                .
         'Total Trailer Axle Load'  (P1 + P2 + … etc

where :

e is values of 'E' in the range 0.2 - 1.0

C is the ratio of output to input signal strength for the 'Control System' for the 'Axle' concerned

T is the 'Brakes'