DEVELOPMENT OF MAXIMUM ALLOWABLE HITCH LOAD BOUNDARIES FOR TRAILER TOWING

An analytically based approach to specifying a maximum allowable hitch load for passenger cars pulling trailers is presented. The change in tow car steady-state directional stability, i.e., understeer, is the basis for the specification. This handling parameter is a function of hitch load, lateral acceleration, tow car to trailer weight ratio, and the amount of load leveling applied by a Class III hitch. Using these variables, an allowable hitch load range was defined as that which would insure positive tow car understeer up to and including 0.3 g cornering. Over 50 combination-vehicle configurations (using three tow car sizes and eight trailers) were then tested in order to validate and revise the analytical boundaries. Based on these results, a tow car stability criterion derived from maximum hitch load considerations appears a valid format for the trailer user and/or manufacturer. It is recommended that in cases where the manufacturer's maximum hitch load is smaller than the criterion, the manufacturer's limit be given precedence.

• Supplemental Notes:
  • Also published in HS-028 866 (SAE-SP-463), "Recreational Vehicle Dynamics," Warrendale, Pennsylvania, 1980, p 53-62. Presented at the SAE Congress and Exposition, Detroit, 25-29 February 1980.
• Corporate Authors:

  Society of Automotive Engineers (SAE)

  400 Commonwealth Drive
  Warrendale, PA  United States  15096
• Authors:
  • Klein, R H
  • Szostak, H T
• Publication Date: 1980

Media Info

• Features: References;
• Pagination: 10 p.

Subject/Index Terms

• TRT Terms: Driving; Handling characteristics; Loads; Mechanical stability; Motor vehicles; Steering; Towing devices; Trailers
• Old TRIS Terms: Cornering (Vehicle); Steering control
• Subject Areas: Motor Carriers; Safety and Human Factors;

Filing Info

• Accession Number: 00391861
• Record Type: Publication
• Source Agency: National Highway Traffic Safety Administration
• Report/Paper Numbers: SAE 800157, HS-028 873
• Contract Numbers: DOT-HS-7-01720
• Files: HSL, USDOT
• Created Date: Jan 30 1985 12:00AM