Document ID: chunk:federal_register_of_legislation:F2021C00476:body:0:p43
Version: federal_register_of_legislation:F2021C00476
Segment Type: other
Provision Reference: 
Character Range: 120045–123110

km/h, while alternating between the two test speeds after each stop. With the vehicle laden, repeat the five stops at each test speed while alternating between the two test speeds.
            (f) Test surface: This test is conducted on a road test surface affording good adhesion.
            (g) Data to be recorded:  The following information must be automatically recorded in phase continuously throughout each test run such that values of the variables can be cross referenced in real time:
                 (i) Vehicle speed
                 (ii) Brake pedal force
                 (iii) Angular velocity of each wheel
                 (iv) Brake torque at each wheel
                   (v) Hydraulic line pressure in each brake circuit, including transducers on at least one front wheel and one rear wheel downstream of any operative proportioning or pressure limiting valve(s)
                   (vi) Vehicle deceleration

            (h)  Sample rate: All data acquisition and recording equipment shall support a minimum sample rate of 40 Hz on all channels.
            (i)  Determination of front versus rear brake pressure: Determine the front versus rear brake pressure relationship over the entire range of line pressures.  Unless the vehicle has a variable brake proportioning system, this determination is made by static tests.  If the vehicle has a variable brake proportioning system, dynamic tests are run with the vehicle both laden and unladen.  Fifteen snubs from 50 km/h are made for each of the two load conditions, using the same initial conditions specified in this appendix.

          4. DATA REDUCTION

            (a) The data from each brake application prescribed in paragraph 3.(e) above is filtered using a five-point, on-centre moving average for each data channel.
            (b) For each brake application prescribed in paragraph 3.(e) above, determine the slope (brake factor) and pressure axis intercept (brake hold-off pressure) of the linear least squares equation best describing the measured torque output at each braked wheel as a function of measured line pressure applied at the same wheel.  Only torque output values obtained from data collected when the vehicle deceleration is within the range of 0.15 g to 0.80 g are used in the regression analysis.
            (c) Average the results of paragraph (b) above to calculate the average brake factor and brake hold-off pressure for all brake applications for the front axle.
            (d) Average the results of paragraph (b) above to calculate the average brake factor and brake hold-off pressure for all brake applications for the rear axle.
            (e) Using the relationship between front and rear brake line pressure determined in paragraph 3.(i) above and the dynamic tyre rolling radius, calculate the braking force at each axle as a function of front brake line pressure.
            (f) Calculate the braking rate of the vehicle as a function of the front brake line pressure using the following equation:

                          where z  = braking