Designing trucks for good ride characteristics is a challenge to
the engineer, given the many design constraints imposed by
requirements for transport productivity and efficiency. The
objective of this lecture is to explain why trucks ride as they do,
and the basic mechanisms involved.
The response of primary interest is the vibration to which the
driver is exposed in the cab. Whole-body vibration tolerance curves
give an indication of how those vibrations are perceived at the
seat; however, ride studies have shown that visual and hand/foot
vibrations are also important to the perception of ride in
trucks.
The ride environment of the truck driver is the product of the
applied excitation and the response properties of the truck. The
major excitation sources are road roughness, the rotating
tire/wheel assemblies, the driveline, and the engine. In the
low-frequency range the truck's response to these inputs is
predictable from rigid-body models of the basic suspension
isolation mechanisms, and the pitch-plane tuning to road inputs
characterized by "wheelbase filtering." At higher
frequencies, the response is influenced by frame bending, cab
mounting, fifth wheel position, trailer loading, and other
variables. Examples of the influences on ride from these many
variables are given
