Development of Car/Trailer Handling and Braking Standards. Volume IV: Technical Report for Phase II - Front Wheel Drive Tow Cars

摘要

This report verifies the handling and braking performance requirements proposed in Vol. II for passenger cars towing trailers. This includes straight line braking, trailer swing stability, tow car steady turn stability, and combined brake-in-turn stability. Over 500 combinations vehicle tests with three trailers and two front wheel drive tow cars (in 34 different configurations), plus the results of previous trailer towing research have been integrated into proposed performance criteria, and a compliance format based on tow car and trailer characteristics. For straight line braking performance a combination-vehicle (CV) deceleration criteria of 0.4g is recommended. A tow car weight requirement based on trailer brake capability is presented to insure the CV will meet this deceleration requirement. For unbraked trailers the tow car gross weight rating should never be less than 1.5 times the trailer weight. For trailer swing stability the safety-related performance measure is damping ratio, or the equivalent cycles to one-half amplitude. A minimum damping ratio of 0.15 (or 3/4 cycles to 1/2 amplitude) is recommended. Test procedures and analysis curves are presented which can be used to determine damping ratio for each trailer.