Procedures to analyze the tractor load would be different,
depending on the purpose. Many researchers have used simple
statistics such as average, maximum, and minimum values in order
to represent the load. This method extracts representative values
to show the difference of amplitude, but this simplification
prohibits characterizing the whole load profiles since the field load
is irregular. Effects of gear setting on the transmission and PTO
load, One-Way ANOVA and the least significant difference test
(LSD) were conducted with SAS (version 9.1, SAS Institute, Cary,
USA). Also, it is difficult to represent effects of the load on the
tractor since the load causes damages to the tractor, and fatigue of
the tractor parts also needs to be investigated. Fatigue of a tractor is
defined as the damage sum from repeated loadings (Lampman,
1997).