Dynamics and Roll Stability of a Loaded Class 8 Tractor-Livestock Semi-Trailer

The transporting of live cattle involves the use of Class 8 tractors and livestock semi-trailers for transportation from farms and feedlots to processing plants. This travel may include unimproved roads, local streets, two lane highways, as well as interstate highways. Typically, cattle are compartmentalized in a “double deck” fashion as it provides utility and comports with size and weight limits for commercial Class 8 vehicles.

Concern has been expressed for the effect of cattle movement upon the dynamic performance of the loaded Class 8 tractor-livestock trailer assembly. Loading guidelines exist for cattle that attempt to prevent injury or debilitation during transit, and literature exists on the orientation and some kinematics of loaded cattle.

Considerable literature exists on the effect of liquid slosh in tankers and swinging beef carcasses suspended from hooks in refrigerated van trailers on the dynamic response and roll stability of those vehicles. However, no research is reported on the case of a loaded livestock trailer-although it is analogized (incorrectly) to the above. This research focuses specifically on loaded Class 8 tractors and livestock semi-trailers.

The authors have engaged in an extensive program involving the five following components:

1. 1.
   Extensive full scale testing of loaded livestock trailers in accepted test protocols including:

   1. a
      Tilt table tests (SAE J2180)
   2. b
      U-turn maneuvers (SAE J2181)
   3. c
      200 ft. radius turns (SAE J2181)
   4. d
      Slalom maneuver (ISO 7401)
   5. e
      Highway Evasive maneuver (ISO 3888)
2. 2.
   Driving on public roads at highway speeds
3. 3.
   Simulation of the tractor-trailer using EDVDS to perform the driving maneuvers in the computer environment.
4. 4.
   Comparison to quasi-static analysis using a static roll model (SRM).
5. 5.
   Analysis of videotape of cattle during test maneuvers.