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Emission Test Cycles

Low Load Cycle (LLC)

Time-speed-torque data points

The Low Load Cycle (LLC) has been developed at the SwRI for the California Air Resources Board (CARB) for use in low NOx emission regulations for heavy-duty onroad engines [4430]. The test represents real-world urban tractor and vocational vehicle operations, characterized by low engine loads. The long duration of the test (5505 s = 1 hr 31 min 44 s) was selected to ensure that continuous active thermal management of the engine and its aftertreatment system be required. The test includes an engine dynamometer and a chassis dynamometer (vehicle) versions, Figure 1.

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Figure 1. Low Load Cycle (LLC)

The following are selected parameters of the Low Load Cycle (vehicle version):

  • Total distance: 25269.9 m
  • Time: 5505 s
  • Idle time: 2171 s
  • Average speed: 16.53 km/h
  • Average driving speed (excluding stops): 27.29 km/h
  • Maximum speed: 82.8 km/h
  • Average acceleration: 0.27 m/s2
  • Maximum acceleration: 1.59 m/s2

Acceleration was calculated using central difference method.

Acknowledgement: This article based in part on information provided by Chris Sharp of the Southwest Research Institute.