Device for pushing and pulling implements, including cables, into and from conduits and the like

Claim 1

In combination, a housing having a passage disposed tangentially to a circular series of rollers rotatable in said housing; a spool in said housing journaled for rotation therein by engagement of its periphery with said roller; reversible drive means for driving said spool in opposite directions; a spirally coiled element on said spool adapted to be payed out through said passage when said spool is driven in one direction with the outer convolution engaged with said rollers and to be pulled in through said passage for rewinding on said spool when the latter is driven in the opposite direction; an implement and opeating means therefor secured to said element for movement of said implement lengthwise in opposite directions of a pipe and the like responsive to rotation of said spool in opposite directions; another spool adjacent to said housing driven in opposite directions by said drive means and having said operating means coiled thereabout for unwinding therefrom and rewinding thereonto responsive to movement of said element and implement in opposite directions; one of said rollers being radially movably supported in said housing and spring biased toward said spool and the outer convolution of said element; and switch means operative to deenergize said drive means during pay out of said element upon predetermined radial outward movement of said one roller by predetermined arching of said element between the rollers next adjacent to said one roller by compressive load on said element; such predetermined arching of said element detecting excessive resistance to pay out movement of said implement and being effective through said switch means to deenergize said drive means.