Low Load Cycle (LLC)
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 LLC test has also been adopted by the US EPA for emission certification of model year 2027 and later heavy-duty engines.
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.
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.