Document ID: chunk:federal_register_of_legislation:F2011C00805:reg:21:p3
Version: federal_register_of_legislation:F2011C00805
Segment Type: reg
Provision Reference: reg 21 (pt 3/7)
Character Range: 222745–226171

used for force or torque calibration.

         3.  SETTING OF THE DYNAMOMETER

         3.1. Setting method

         3.1.1. Introduction

         This method is not a preferred method and shall be used only with fixed load curve shape dynamometers for determination of load setting at 80 km/h and cannot be used for vehicles with compression-ignition engines.

         3.1.2. Test instrumentation

         The vacuum (or absolute pressure) in the vehicle's intake manifold shall be measured to an accuracy of ± 0.25 kPa.  It shall be possible to record this reading continuously or at intervals of no more than one second.  The speed shall be recorded continuously with a precision of ± 0.4 km/h.

         3.1.3. Road test

         3.1.3.1. Ensure that the requirements of paragraph 4. of Appendix 3 to this Annex are met.

         3.1.3.2. Drive the vehicle at a steady speed of 80 km/h, recording speed and vacuum (or absolute pressure) in accordance with the requirements of paragraph 3.1.2. above.

         3.1.3.3. Repeat procedure set out in paragraph 3.1.3.2. above three times in each direction.  All six runs must be completed within four hours.

         3.1.4. Data reduction and acceptance criteria

         3.1.4.1. Review results obtained in accordance with paragraphs 3.1.3.2. and 3.1.3.3. above. (Speed must not be lower than 79.5 km/h or greater than 80.5 km/h for more than one second).  For each run, read vacuum level at one second intervals, calculate mean vacuum  and standard deviation (s).  This calculation shall consist of no less than 10 readings of vacuum.

         3.1.4.2. The standard deviation must not exceed 10 per cent of the mean  for each run.

         3.1.4.3. Calculate the mean value  for the six runs (three runs in each direction).

         3.1.5. Dynamometer setting

         3.1.5.1. Preparation

         Perform the operations specified in paragraphs 5.1.2.2.1. to 5.1.2.2.4. of Appendix 3 to this Annex.

         3.1.5.2. Load setting

         After warm-up, drive the vehicle at a steady speed of 80 km/h and adjust dynamometer load to reproduce the vacuum reading  obtained in accordance with paragraph 3.1.4.3. above.  Deviation from this reading shall be no greater than 0.25 kPa.  The same instruments shall be used for this exercise as were used during the road test.

         3.2. Alternative method

         With the manufacturer's agreement the following method may be used.

         3.2.1. The brake is adjusted so as to absorb the load exerted at the driving wheels at a constant speed of 80 km/h, in accordance with the following table:

Reference mass of vehicle  Equivalent inertia  Power and load absorbed by the dynamometer at 80 km/h  Coefficients

                                                                                                                    a    b

Rm (kg)                    kg                  kW                                                     N             N    N/(km/h)

            Rm    480      455                3.8                                                    171           3.8  0.0261

  480 < Rm    540          510                4.1                                                    185           4.2  0.0282

  540 < Rm    595          570                4.3                                                    194           4.4  0.0296

  595 < Rm    650          625                4.5