Roll Test

The vehicle chassis is exercised in roll. This may be done about a fixed axis in the ground plane, or it may be done about a “natural” roll axis. In the natural axis test, compensation is provided to allow pitch and heave in order to maintain constant front and rear axle loads. This results in vehicle roll about its “natural” roll axis. Roll tests are accomplished by moving the K&C rig’s center table in roll within defined displacement bounds (For example, + 1.5 degrees from baseline ride height, zero roll angle). The vehicle chassis is clamped directly to the center table, thus it is exercised in roll as well.

During a roll test lateral and longitudinal forces, and aligning moments are maintained at zero at each tire contact patch, thus canceling any unwanted tire “scrub” forces, and allowing the suspension to move freely without binding. The slow speed of this test (cycle times are typically ~ 1 minute) removes unwanted damper and inertial forces from the tire vertical load measurements. Corresponding loads, displacements, and orientations are measured at each of the four wheels.

Here are some characteristics that are measured in a Roll Test:

  • Axle Steer
  • Total Roll Steer
  • Tire Vertical Force
  • Total Roll Camber
  • Total Roll Stiffness
  • Track Width Change
  • Suspension Roll Steer
  • Suspension Roll Camber
  • Suspension Roll Stiffness
  • Static Roll Weight Transfer
  • Coefficient
  • Wheel Rates in Roll
  • Friction / Hysteresis
  • Tire Contact Patch (TCP) Lateral
  • Displacementy