We consider a class of mechanical systems arising from the dynamics of multi-segmental animal locomotion. Our earlier paper has revealed that a chain of body segments oscillate in a natural mode if the head is externally forced to move at a constant velocity and the damping effect is reduced by an appropriate amount. In this paper, we further show that the natural oscillations, in turn, generate a stable forward velocity (of the head) through a rectification mechanism. As a result, an autonomous locomotion behavior is obtained.