Document ID: chunk:federal_register_of_legislation:F2010C00150:front:0:p32
Version: federal_register_of_legislation:F2010C00150
Segment Type: other
Provision Reference: 
Character Range: 86642–89399

one of the following criteria, then it passes this wheel lockup sequence requirement:

(1) No wheels lock;

         (2) Both wheels on the front axle and one or no wheels on the rear axle lock;

(3) Both axles simultaneously lock.

         (c) If wheel lockup commences at a braking rate less than 0.15 and more than 0.8m/ s2 then the test is invalid and should be repeated on a different road surface.

         (d) If, either laden or unladen, at a braking rate between 0.l5 and 0.8m/s2 both wheels on the rear axle and one or no wheels on the front axle lock, then it fails the wheel lockup sequence test. In this latter case, the vehicle must be submitted to the 'torque  wheels'  test  procedure  to  determine  the  objective  brake  factors  for calculation of the adhesion utilization curves.

Annex 5- Appendix 2

TORQUE WHEEL TEST PROCEDURE

1. GENERAL INFORMATION

          The purpose of this test is to measure the brake factors and thus determine the adhesion utilization of the 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 degrees C and 100 degrees C average on the hottest axle.

(b) Test speeds : 100km/h and 50km/h.

         (c) Pedal force: Pedal force is increased at a linear rate between 100 and 150N/sec   for the 100km/h test speed, or between 100 and 200N/sec for the 50km/h test speed, until the first axle locks or until a pedal force of 1kN is reached, whichever occurs first.

         (d) Brake cooling: Between brake applications, the vehicle is driven at speeds up to 100km/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 100km/ h and five stops from a speed of 50km/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:

(1) Vehicle speed

(2) Brake pedal force

(3) Angular velocity of each wheel

(4) Brake torque at each wheel

         (5) 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)

(6)