Abstract: A device is composed of relatively rotatable cylindrical components one of which has a groove forming a raceway or track of part-helical form containing a set of balls in contact with a plain surface of the other component. The raceway wedges with the balls to resist direct axial motion between the components. Rotation of one component causes the balls to move around the raceway and be guided from the end to the start thereof under sufficient traction to cause linear motion of the other component.

Abstract: A marking device includes a case which may be held by a user in the fashion of conventional writing and marking instruments. A ball point pen, felt tip pen, pencil or crayon is positioned within the case. In the instances of the pens, a soft iron collar is fixed or adjustably connected to the pen. In the instances of the pencil or crayon, a movable, hollow, soft iron collar is positioned about the pencil or crayon, a plurality of balls of non-magnetic, non-magnetizable material are provided within the collar to hold the pencil or crayon in fixed, preferably adjustable, position when the collar is moved downwardly. An electro-magnet or solenoid responsive to electrical signals or pulses is placed in the vicinity of the fixed or movable soft iron collar.