Fresh fruits and vegetables experience losses enroute to market that a
re caused by mechanical injuries. Past studies have indicated that tra
nsit vibration contributes to this loss, and may be more important tha
n impacts as a source of damage. In cross-country tests of cherries, n
ectarines, and pears in semi-trailers equipped with steel-spring suspe
nsion systems, highest Power Spectral Density (PSD) levels were found
at about 3.5 Hz. In this study, PSD is used to mean acceleration spect
ral density. Other frequencies with high PSD levels were 9, 18, and 25
Hz. Similar results were found in tests with fresh tomatoes. However,
in trailers equipped with an air-ride suspension and loaded with toma
toes, the PSD levels were attenuated at 3.5 Hz, and were reduced at ot
her frequencies. The highest PSD levels were found at the rear of the
trailer, with resonance in the loaded boxes occurring at some frequenc
ies. Horizontal acceleration was much less than the vertical accelerat
ion. Understanding acceleration levels and frequencies that occur duri
ng shipment of perishables in refrigerated trailers will help to deter
mine methods that will dampen the vibration energy and reduce the pres
ent losses in produce quality.