A TRACK TO TWIN ROLL DYNAMOMETER COMPARISON OF SEVERAL DIFFERENT METHODS OF VEHICLE VELOCITY SIMULATION

The current EPA test procedure for fuel economy and emissions testing uses a twin roll dynamometer obtaining a speed signal from the rear roll and simulating the forces at the front roll. With the rolls coupled only by the drive wheels of the vehicle, the front roll travels approximately 2% slower than the rear roll at steady-state 50 mph, resulting in approximately a 4% overprediction of fuel economy. Coupling the rolls externally equalizes the roll speeds at a value which better simulates the road velocity and therefore better predicts the fuel economy. This report describes the test program and data analysis which led to these conclusions.

• Corporate Authors:

  Environmental Protection Agency

  Standards Development & Support Branch, 2565 Plymouth Road
  Ann Arbor, MI  United States  48105
• Authors:
  • Yurko, J
• Publication Date: 1979-6

Media Info

• Pagination: 26 p.

Subject/Index Terms

• TRT Terms: Accuracy; Couplers; Dynamometers; Exhaust gases; Fuel consumption; Motor vehicles; Road tests; Simulation; Test procedures; Velocity
• Subject Areas: Energy; Highways; Vehicles and Equipment; I95: Vehicle Inspection;

Filing Info

• Accession Number: 00313419
• Record Type: Publication
• Source Agency: National Technical Information Service
• Report/Paper Numbers: EPA-AA-SDSB-79-26 Tech Rpt.
• Files: TRIS
• Created Date: Jun 26 1980 12:00AM