Document ID: chunk:federal_register_of_legislation:F2024L00446:reg:16:p33
Version: federal_register_of_legislation:F2024L00446
Segment Type: reg
Provision Reference: reg 16 (pt 33/108)
Character Range: 977478–980690

period.
              2.3.1.2.3. The speed difference of all roller speeds shall be within ±0.16 km/h.
              2.3.1.3.  The usage of twin roller dynamometers with 4WD configuration should be accepted if the following conditions are met:
                  (a)  The separation distance between the front and rear sets of twin rollers of the dynamometer (X in diagram below) is set as closely as possible to match the manufacturer's declared wheelbase of the vehicle to be tested, and
                  (b)  It shall be ensured that the setting of the separation distance between the roller sets used for dyno load setting is reproduced for vehicle testing.
              2.3.2. Vehicle restraint system for single roller chassis dynamometers
              2.3.2.1. Vertical force
               In addition to the requirement of paragraph 7.3.3.1.3. of Annex B4, the restraint system shall be designed so that the vertical force imposed to the vehicle is minimised and is the same during the chassis dynamometer setting and all tests. This criteria is fulfilled, if either the restraint system is designed such that it cannot impose any different vertical force, or if a procedure to demonstrate how this requirement can be met is agreed between the responsible authority and the manufacturer.
              2.3.2.2. Restraint stiffness
               The restraint system shall exhibit sufficient stiffness in order to minimize any movements and rotations. Only limited movements along the z-axis and rotations over the y-axis are allowed to avoid non-negligible effects towards the test results and to fulfil the requirements of paragraph 2.3.2.1. of this annex.
              2.4. Chassis dynamometer calibration
              2.4.1. Force measurement system
              The accuracy of the force transducer shall be at least ±10 N for all measured increments. This shall be verified upon initial installation, after major maintenance and within 370 days before testing.
              2.4.2. Dynamometer parasitic loss calibration
              The dynamometer's parasitic losses shall be measured and updated if any measured value differs from the current loss curve by more than 9.0 N. This shall be verified upon initial installation, after major maintenance and within 35 days before testing.
              2.4.3. Verification of road load simulation without a vehicle
              The dynamometer performance shall be verified by performing an unloaded coastdown test upon initial installation, after major maintenance, and within 7 days before testing. The arithmetic average coastdown force error shall be less than 10 N or 2 per cent, whichever is greater, at each reference speed point.
              3. Exhaust gas dilution system
              3.1. System specification
              3.1.1. Overview
              3.1.1.1. A full flow exhaust dilution system shall be used. The total vehicle exhaust shall be continuously diluted with ambient air under controlled conditions using a constant volume sampler. A critical flow venturi (CFV) or multiple critical flow venturis arranged in parallel, a positive displacement pump (PDP), a subsonic venturi (SSV), or an ultrasonic flow meter (UFM)