EFFECTS OF WEIGHT DISTRIBUTING HITCH TORQUE ON CAR-TRAILER DIRECTIONAL CONTROL AND BRAKING

This report presents the results of a full scale test program, with supporting computer simulation analysis, aimed at determining the effects of weight-distributing hitch forces (or torque) on combination-vehicle (C-V) handling and braking. Two C-V configurations were used; a full sized station wagon plus 31 ft travel trailer, and a compact sized sedan plus 18 ft utility trailer. Test procedures included a step steer (for tow vehicle understeer changes and transient response), a pulse steer (for trailer swing mode damping), straight line braking (for stopping distance), and braking in a turn (for transient understeer changes). Over 800 test runs were performed in which load leveling torque, hitch load, and tire pressure were the primary independent variables. Results show that increasing hitch load and/or load leveling torque degrade the tow vehicle understeer and reduce the speed for incipient jackknifing. On the other hand, trailer damping is somewhat improved with load leveling. Front/rear tire pressure differentials (front lower than rear) have a significant beneficial influence when the hitch load is high.

• Corporate Authors:

  Systems Technology, Incorporated

  13766 South Hawthorne Boulevard
  Hawthorne, CA  United States  90250

  National Highway Traffic Safety Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Klein, R H
  • Szostak, H T
• Publication Date: 1977-10

Media Info

• Pagination: 143 p.

Subject/Index Terms

• TRT Terms: Automobiles; Braking; Jackknifing; Loads; Passenger vehicles; Physical distribution; Pressure; Settlement (Structures); Stability (Mechanics); Steering; Tires; Torque; Towing vehicles; Trailers; Weight
• Old TRIS Terms: Load settlement; Steering control; Weight control
• Subject Areas: Freight Transportation; Highways; Safety and Human Factors; Vehicles and Equipment;

Filing Info

• Accession Number: 00175550
• Record Type: Publication
• Source Agency: National Technical Information Service
• Report/Paper Numbers: DOT-HS-803-248 Final Rpt., STI-TR-1098-1
• Contract Numbers: DOT-HS-7-01548
• Files: TRIS, USDOT
• Created Date: Jun 14 1978 12:00AM