Device for checking bent tubes by a probe, such as a pneumatically propelled eddy-current probe

Claim 1

Apparatus for inspecting curved tubes, such as helical heat exchanger tubes, comprising a sealed enclosure, a probe comprising a cable having floaters of larger diameter than the cable fixed thereto at lengthwise spaced intervals and having at a front end thereof a sensing head comprising electrical induction windings that are connectable with measuring apparatus by means of conductors extending along the cable, a rotatable cable winding means located within said enclosure to which the rear end of the cable is connected and about which the cable is normally coiled, connecting means through which said cable can pass for providing a sealed connection between said enclosure and one end of a tube to be inspected, and means for introducing into said enclosure a pressure fluid which flows through said connecting means and the tube to be inspected and is exhausted from the other end of said tube and whereby the probe is propelled through said tube from said one end thereof towards said other end, said apparatus being characterized by: A. a pulley confined to rotation in said enclosure at a location between said cable winding means and said connecting means and having a peripheral groove in which said cable is receivable; B. deceleration means for controlledly retarding rotation of said pulley to prevent its rotational speed from exceeding a predetermined value; and C. cable engaging means for maintaining the cable engaged in said groove in the pulley around a substantial portion of the periphery thereof so that the speed at which the probe is propelled through a tube to be inspected is controlled by the speed at which the pulley is permitted to rotate, said cable engaging means comprising (1) an endless belt, (2) a plurality of rollers about which said belt is trained and which are arranged to define a stretch of the belt that embraces said portion of the periphery of the pulley and engages the cable at the side thereof that is opposite the pulley, and (3) means for maintaining said stretch of the belt under yielding lengthwise tension that accommodates passage of floaters between the belt and the pulley.