Arm release system for well logging apparatus

摘要

A well logging instrument includes a body member supporting one or more arm members which may be biased outwardly against the sidewalls of the borehole. The arm members may be held in a closed position, adjacent the body member, during entry into a borehole by a heat sensitive retaining member. As the instrument is exposed to borehole temperature the heat sensitive retaining member will within a preselected temperature range release the arm member allowing the arm members to expand outwardly from the body member into contact with the sides of the borehole.