Document ID: chunk:federal_register_of_legislation:F2012C00283:reg:21:p2
Version: federal_register_of_legislation:F2012C00283
Segment Type: reg
Provision Reference: reg 21 (pt 2/39)
Character Range: 262209–265145

be demonstrated to be equivalent to mechanical inertia systems. The means by which               equivalence is established are described in Appendix 6 to this annex.

       1.1.3.  In the event that the total resistance to progress on the road cannot be  reproduced on the chassis dynamometer between speeds of 10 km/h and 120 km/h, it is recommended that a chassis dynamometer having the characteristics defined below should be used.

              1.1.3.1. The load absorbed by the brake and the chassis dynamometer internal frictional effects between the speeds of 0 and 120 km/h is as follows:

                F = (a + b·V2) ±0.1·F80 (without being negative)

 Where:
 F       =  total load absorbed by the chassis dynamometer (N),
 a       =  value equivalent to rolling resistance (N),
 b       =  value equivalent to coefficient of air resistance (N/(km/h)2),
 V       =  speed (km/h),
 F80     =  load at 80 km/h (N).

1.2.  Specific Requirements
1.2.1.  The setting of the dynamometer shall not be affected by the lapse of time. It   shall not produce any vibrations perceptible to the vehicle and likely to                             impair the vehicle's normal operations.
1.2.2.  The chassis dynamometer may have one or two rollers. The front roller shall   drive, directly or indirectly, the inertial masses and the power absorption                             device.
1.2.3.  It shall be possible to measure and read the indicated load to an accuracy   of 5 per cent.

       1.2.4.  In the case of a dynamometer with a fixed load curve, the accuracy of the load setting at 80 km/h shall be 5 per cent. In the case of a dynamometer with adjustable load curve, the accuracy of matching dynamometer load to road load shall be 5 per cent at 120, 100, 80, 60, and 40 km/h and 10 per cent at 20 km/h. Below this, dynamometer absorption shall be positive.

1.2.5.  The total inertia of the rotating parts (including the simulated inertia where   applicable) shall be known and shall be within 20 kg of the inertia class for                             the test.
1.2.6.  The speed of the vehicle shall be measured by the speed of rotation of the   roller (the front roller in the case of a two-roller dynamometer). It shall be                             measured with an accuracy of 1 km/h at speeds above 10 km/h.
                The distance actually driven by the vehicle shall be measured by the movement of rotation of the roller (the front roller in the case of a two-roller dynamometer).
        2.  Dynamometer calibration procedure

 2.1.  Introduction

                 This section describes the method to be used to determine the load absorbed by a dynamometer brake. The load absorbed comprises the load absorbed by frictional effects and the load absorbed by the power-absorption device.

                The dynamometer is brought into operation beyond the range of test speeds. The device used