Document ID: chunk:federal_register_of_legislation:F2021C01192:body:0:p41
Version: federal_register_of_legislation:F2021C01192
Segment Type: other
Provision Reference: 
Character Range: 109585–112317

front and rear axles over a range of braking rates between 0.15 and 0.8.
2.  Vehicle conditions
(a) Vehicle load: Laden and unladen
(b) Transmission position: Engine disconnected
3. Test conditions and procedures
(a) Initial brake temperature: Between 65 °C and 100 °C average on the hottest axle.
(b) Test speeds: 100 km/h and 50 km/h.
(c) Pedal force: Pedal force is increased at a linear rate between 100 and 150 N/sec for the 100 km/h test speed, or between 100 and 200 N/sec for the 50 km/h test speed, until the first axle locks or until a pedal force of 1 kN is reached, whichever occurs first.
(d) Brake cooling: Between brake applications, the vehicle is driven at speeds up to 100 km/h until the initial brake temperature specified in paragraph 3.(a) above is reached.
(e) Number of runs: With the vehicle unladen, run five stops from a speed of 100 km/h and five stops from a speed of 50 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 shall 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