Abstract: The invention pertains to apparatus for positioning a gage and structure associated with the gage, such as a protective shield. A gage arm is mounted for linear movement upon a column, and the arm extends through structure which surrounds the arm forming a shield protecting the gaging apparatus from foreign matter. Power means position the gage arm protective shield and sensors determining the relative position between the shield and the gage arm control the position of the shield to prevent the shield from having an adverse effect upon the gage arm measurement. A lost motion linkage may interconnect the gage arm support with the shield for the positioning thereof, or the gage arm support may be positioned independently.