Document ID: chunk:federal_register_of_legislation:F2024L00446:reg:16:p26
Version: federal_register_of_legislation:F2024L00446
Segment Type: reg
Provision Reference: reg 16 (pt 26/108)
Character Range: 957132–960359

load coefficients f0a, f1a and f2a, shall be used only for the purpose of paragraph 7.3.4.3.3. of this annex. For other purposes, the target road load coefficients f0, f1 and f2, shall be used as the target road load coefficients.

              7.3.4.3.5. Details of the procedure and of its equivalency shall be provided to the responsible authority.

              8. Chassis dynamometer load setting

              8.1. Chassis dynamometer load setting using the coastdown method
              This method is applicable when the road load coefficients f0, f1 and f2 have been determined.
              In the case of a road load matrix family, this method shall be applied when the road load of the representative vehicle is determined using the coastdown method described in paragraph 4.3. of this annex. The target road load values are the values calculated using the method described in paragraph 5.1. of this annex.
              8.1.1. Initial load setting
              For a chassis dynamometer with coefficient control, the chassis dynamometer power absorption unit shall be adjusted with the arbitrary initial coefficients, Ad, Bd, and Cd, of the following equation:
           where:
           Fd is the chassis dynamometer setting load, N;
           v is the speed of the chassis dynamometer roller, km/h.
              The following are recommended coefficients to be used for the initial load setting:
                  (a)
                  for single-axis chassis dynamometers, or
                  for dual-axis chassis dynamometers, where At, Bt and Ct are the target road load coefficients;
                  (b) Empirical values, such as those used for the setting for a similar type of vehicle.
              For a chassis dynamometer of polygonal control, adequate load values at each reference speed shall be set to the chassis dynamometer power absorption unit.
              8.1.2. Coastdown
              The coastdown test on the chassis dynamometer shall be performed with the procedure given in paragraphs 8.1.3.4.1. or 8.1.3.4.2. of this annex and shall start no later than 120 seconds after completion of the warm-up procedure. Consecutive coastdown runs shall be started immediately. At the request of the manufacturer and with approval of the responsible authority, the time between the warm-up procedure and coastdowns using the iterative method may be extended to ensure a proper vehicle setting for the coastdown. The manufacturer shall provide the responsible authority with evidence for requiring additional time and evidence that the chassis dynamometer load setting parameters (e.g. coolant and/or oil temperature, force on a dynamometer) are not affected.
              8.1.3. Verification
              8.1.3.1. The target road load value shall be calculated using the target road load coefficient, At, Bt and Ct, for each reference speed, vj:
           where:
                      At, Bt and Ct are the target road load parameters;
                      Ftj is the target road load at reference speed vj, N;
                      vj is the jth reference speed, km/h.
           8.1.3.2. The measured road load shall be calculated using the following equation:
           where: