The Heavy Heavy-Duty Diesel Truck (HHDDT) schedule is a chassis dynamomter test developed by the California Air Resources Board with the cooperation of West Virginia University.
The test consists of four speed-time modes, including idle, creep (shown in Figure 1), transient (Figure 2) and (high speed) cruise (Figure 3).
Figure 1. HHDDT Creep Mode
Figure 2. HHDDT Transient Mode
Figure 3. HHDDT Cruise Mode
Selected statistics for the particular HHDDT modes are compared with those for the UDDS cycle in the following table.
|Parameter||HHDDT Creep||HHDDT Transient||HHDDT Cruise||UDDS|
|Average Speed, mph||1.77||15.4||39.9||18.8|
|Max. Speed, mph||8.24||47.5||59.3||58|
|Max. Acceleration, mph/s||2.3||3.0||2.3||4.4|
|Max. Deceleration, mph/s||-2.53||-2.8||-2.5||-4.6|
|Total KE, mph2||3.66||207.6||1036||373.4|