Arrangement for electromechanical axial clearance measurement

In an arrangement for the electromechanical measurement of the axial clearance of rotating elements, particularly for the measurement of the axial clearance of shafts in high-speed turbomachinery, including a housing fixed in position relative to a measured object;

• a rotatable member supported in said housing;
• a motor driving said rotatable member;
• sensor means connected to said rotatable member and being movable towards said measured object and, responsive to the triggering of a contact impulse, being movable away from said measured object, said sensor means being electrically insulated from said housing and from said measured object, the improvement comprising:
• (a) said rotatable member being the extended shaft of said drive motor extending substantially perpendicular to the axis of rotation of a rotating element in the operating condition of the former and parallel to the measured object;
• said sensor means including an eccentric feeler fastened to the end of said shaft proximate the measured object;
• (b) an absolute angle-measuring encoder for defining the zero position of said shaft and determining a change in distance between said eccentric feeler and said measured object from a concurrently occurring change in the angle of rotation of said shaft;
• and
• (c) indicator means for measuring a contact resistance so as to generate a contact signal responsive to falling below a resistance threshold value between the electrically-insulated eccentric feeler and said measured object during movement of said eccentric feeler in a direction towards said measured object whereby there is stored the instantaneous indicated value of said absolute angle-measuring encoder and said drive motor concurrently controlled so as to reverse the direction of rotation of said shaft into the zero position thereof.