The preliminary experiment consisted of examining
two types of the seats, one with under a suspension
and other with rear a suspension. The seat with rear
suspension was adopted in this study because it could
be save a space above operators' head in a cabin of
the machinery so as to construct a smaller cabin due
to the design consisting of two steel springs and one
damping element. Then, two types of seats with rear
suspension, one was a vertical suspension system and
the other was an oblique suspension system moves
obliquely to maintain stability of foot condition
during an operation in the Fig