When the tiller was under static condition while its
engine was idle, the second unbalanced inertia force of
the engine was the reason why the handle vibrated
violently. When the tiller was under static condition
while its engine was medium speed, the combustion
excitation force of the engine caused handle vibrating
violently. When the engine operated at high speed, the
first unbalanced inertia force of the engine was the main
reason why handle vibrated violently.