An anti-rotation element prevents relative rotation there between.

The spring (106) enables relative rotation in the first direction, but prevents relative rotation in the second direction.

Relative rotation of the pieces may vary.

The intervals in the relative rotation axial direction of both levers alter according to the relative rotation of the levers.

Relative rotation in one direction causes the valve to open, and relative rotation in the opposite direction causes the valve to close.

A locking threaded connection (a) providing free relative rotation in a first direction, (b) preventing unintended relative rotation in a second opposite direction, and (c) enabling intended relative rotation in the second direction.

A prescribed first relative rotation velocity ratio (ρ1) and second relative rotation velocity ratio (ρ2) are set to different values.

The apparatus may also include a relative rotation assembly (129) for providing relative rotation between the load and the packaging material dispenser.

Relative rotation of the first and second members causes relative rotation of the inner and outer rings so that the rolling element rotates and compresses.

The control unit controls the relative rotational phase of an exhaust cam shaft in accordance with the relative rotational phase of an inlet cam shaft.

The cords are sized to resist and dampen relative rotation between the opening (42) and the torsion bar (58).

The valve (7) is in a threaded engagement with the passage (6) and is prevented from rotating with the passage by means of a guide sleeve (10) such that rotation of the cap (5) effects relative rotation between the valve (7) and the passage (6).

Accordingly, the relative rotation between the portions is inhibited, or dampened.

The relative rotation may be limited by resilient stops 1B.

The anchor assembly comprises relative rotation actuator means (42A, 42B) active during rotation of the anchoring device.