Document ID: chunk:federal_register_of_legislation:F2024L00446:reg:16:p19
Version: federal_register_of_legislation:F2024L00446
Segment Type: reg
Provision Reference: reg 16 (pt 19/108)
Character Range: 936698–939902

6.5.2.2.4. The force at each reference speed shall be measured for at least 6 seconds while the vehicle speed is kept constant. The resulting force for that reference speed point FjDyno shall be the arithmetic average of the force during the measurement.

              6.5.2.2.5.  The steps in paragraphs 6.5.2.2.2. to 6.5.2.2.4. inclusive of this annex shall be repeated for each reference speed.

              6.5.2.3. Measurement procedure by deceleration

              6.5.2.3.1. Preconditioning and dynamometer setting shall be performed according to paragraph 6.5.2.1. of this annex. Prior to each coastdown, the vehicle shall be driven at the highest reference speed or, in the case that the alternative warm-up procedure is used at 110 per cent of the highest reference speed, for at least 1 minute. The vehicle shall be subsequently accelerated to at least 10 km/h above the highest reference speed and the coastdown shall be started immediately.

              6.5.2.3.2. The measurement shall be performed according to paragraphs 4.3.1.3.1. to 4.3.1.4.4. inclusive of this annex but excluding paragraph 4.3.1.4.2., where  and  are replaced by . The measurement shall be stopped after two decelerations if the force of both coastdowns at each reference speed point is within ±10 N, otherwise at least three coastdowns shall be performed using the criteria set out in paragraph 4.3.1.4.2. of this annex.

              6.5.2.3.3. The force fjDyno at each reference speed vj shall be calculated by removing the dynamometer set force:

              where:

                  fjDecel is the force determined according to the equation calculating Fj in paragraph 4.3.1.4.4. of this annex at reference speed point j, N;

                  fdj is the force determined to the equation calculating Fd in paragraph 6.5.2.1. of this annex at reference speed point j, N.

              Alternatively, at the request of the manufacturer, cd may be set to zero during the coastdown and for calculating fjDyno.

              6.5.2.4. Measurement conditions

              The vehicle shall be in the condition described in paragraph 4.3.1.3.2. of this annex.

              6.5.3. Measurement result of the flat belt method

              The result of the flat belt dynamometer fjDyno shall be referred to as fj for the further calculations in paragraph 6.7. of this annex.

              6.6. Chassis dynamometer applied for the wind tunnel method

              6.6.1. Criteria

              In addition to the descriptions in paragraphs 1. and 2. of Annex B5, the criteria described in paragraphs 6.6.1.1. to 6.6.1.6. shall apply.

              6.6.1.1. Description of a chassis dynamometer

              The front and rear axles shall be equipped with a single roller with a diameter of not less than 1.2 metres.

              6.6.1.2. Vehicle restraint system

              The dynamometer shall be equipped with a centring device aligning the vehicle. The restraint system shall maintain the centred drive wheel position within the following recommended limits throughout the coastdown runs of the road load determination:

              6.6.1.2.1. Vehicle position

              The vehicle