A conditioning disk actuating system for raising and lowering a conditioning disk inside a conditioning head for the conditioning of semiconductor wafer polishing pads. The system includes a fluid-actuated cylinder which is coupled to a travel hub vertically slidably mounted in a travel housing provided inside the conditioning head. The conditioning disk is mounted on the bottom end of a disk shaft carried by the travel hub. The fluid-actuated cylinder is operated to selectively lower and raise the travel hub and conditioning disk to press the disk against the polishing pad and remove the disk from the polishing pad, respectively. A position sensing mechanism may be provided in the conditioning head for revealing the nullupnull or nulldownnull position of the conditioning disk.