Swing is defined as the rotational motion around the pigtail origin. This pendulum-like movement usually occurs in a vertical plain parallel to the tangent along the head surface at the pigtail origin, as the vicinity of the head restricts large swinging motions in any other direction.

When the pigtail is at rest, swing can be generated by any rotational movement of the head. Once the pigtail is in motion, this swing may be sustained by continuous shaking of the head, but also by a vertical acceleration of the head.