Electromagnetic probe drive apparatus

Apparatus for driving a probe through the interior of individual tubes of a nuclear reactor steam generator, said probe comprising an inspection device for said tubes and said probe connected to an elongated flexible probe carrier, said apparatus comprising:

• a rotatable drive member having a cylindrical drive surface, holding means comprising an arcuate shoe member carrying a plurality of spaced idler rollers, a portion of said elongated flexible probe carrier operable to be retained between a portion of said cylindrical drive surface and said idler rollers with a predetermined frictional force in non-slipping engagement so that rotation of said cylindrical drive surface of said rotatable drive member causes said elongated flexible probe carrier to move with said cylindrical drive surface without slippage;
• motive means comprising a drive motor having a motor drive shaft;
• and
• electromagnetic clutch means providing a remotely controllable and variable degree of magnetic coupling force between said motor drive shaft and said rotatable drive member for normally rotating said cylindrical drive surface of said rotatable drive member to drive said elongated flexible probe carrier and the probe connected thereto through individual ones of said tubes, and the remotely controllable coupling force exerted by said electromagnetic clutch means betweens said motor drive shaft and said rotatable drive member being maintained at less than the predetermined frictional force exerted by said holding means so that in the event motion of said probe through any of said tubes is impeded, said electromagnetic clutch means will be decoupled with respect to transmitting the motion of said motor drive shaft to said rotatable drive member thereby arresting motion of said elongated probe carrier and said probe without causing slippage between said cylindrical drive surface and the portion of said elongated probe carrier which is in contact therewith, the coupling force exerted by said electromagnetic clutch means also being remotely variable so that in the event motion of said probe through any of said tubes is impeded by an obstruction, the coupling force can be remotely increased to exert the necessary coupling force to overcome the obstruction.