Division 8.2.1 Initial load setting

For a chassis dynamometer of coefficient control, the chassis dynamometer power absorption unit shall be adjusted with the arbitrary initial coefficients, A_d, B_d and C_d, of the following equation:

where:

The following coefficients are recommended for the initial load setting:

1. (a)
   $$A_d=\mathrm{0,5}\times \frac{a_t}{\mathrm{r\prime }}{\mathrm{,\; B}}_d=\mathrm{0,2}\times \frac{b_t}{\mathrm{r\prime }}{\mathrm{,\; C}}_d=\frac{c_t}{\mathrm{r\prime }}$$

   for single-axis chassis dynamometers, or

   $$A_d=\mathrm{0,1}\times \frac{a_t}{\mathrm{r\prime }}{\mathrm{,\; B}}_d=\mathrm{0,2}\times \frac{b_t}{\mathrm{r\prime }}{\mathrm{,\; C}}_d=\frac{c_t}{\mathrm{r\prime }}$$

   for dual-axis chassis dynamometers, where:

   a_t, b_t and c_t are are the target running resistance coefficients; and

   r′ is the dynamic radius of the tyre on the chassis dynamometer obtained at 80 km/h, m.; or

2. (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 for the chassis dynamometer power absorption unit.