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Performance testing was done on a 1.219 m (48 in) roll diameter chassis dynamometer to validate its compliance with EPA specifications. The testing procedure and results are presented. Tests include time, speed, acceleration and torque calibration verification, load control response time, parasitic loss compensation and stability, base mechanical inertia verification, road load curve simulation and repeatability, automatic road coastdown coefficient matching, and overall simulation accuracy during severe acceleration and emission test cycles. These testing methods provide an objective and comprehensive evaluation of chassis roll dynamometer performance.

A simple, inexpensive, critical flow blender has been developed for filling a tedlar bag with controllable concentrations of HC, NOx, CO2, and CO gases at levels encountered in automobile emissions testing. According to a daily schedule, a technician takes the bag to all analyzer sites in the laboratory for analysis. The concentrations indicated by each site are compared to the overall averages. The results are stored in a computerized data base from which control charts, statistical analyses, and interpretations of significant differences among test sites can be made. The precision, accuracy, and statistical interpretations of the data are discussed.