Abstract: Apparatus for reciprocatively positioning an article or work object (e.g. an inspection sample or test probe) in precise relation to two separated work stations. The article to be positioned is held in a first carrier having a cam follower attachment. The first carrier is supported shiftably on a second carrier. The second carrier can be reciprocated perpendicular to the plane of the work stations. The cam follower of the first carrier is captured movably in a cam track groove of a stationary plate having two cam track grooves associated with respective said stations. A two-position rotatable cam forms a linking channel between the two tracks. Upon completion of a work operation at one of the stations the second carrier is reciprocated.