Patent ID: 7975342

Claim:
A pig towing device adapted for moving through a conduit having bends and open T intersections, the device comprising: at least a front leading cup and a rear trailing cup adapted to seal with the conduit for propelling the device through the conduit, the leading cup and the trailing cup being spaced apart a predetermined distance whereby at least one of the leading and trailing cups is adapted to maintain the seal with the conduit as the pig towing device negotiates past the open T intersections, and a flexible body interconnecting the front leading cup and the rear trailing cup, the flexible body being urged normally into a straight position extending along a central axis thereof to maintain the front leading cup and the rear trailing cup spaced apart by the predetermined distance, and the flexible body having predetermined limited flexibility permitting it to bend relative to the central axis as the pig towing device negotiates through the bend in the conduit, wherein the flexible body has a first tension means and a flexible compression sleeve means, the first tension means is connected with both the front leading cup and the rear trailing cup for transferring drag forces from the front leading cup to the rear trailing cup, the flexible compression sleeve means surrounds the first tension means and is sandwiched between the front leading cup and the rear trailing cup for transferring compression forces from the rear trailing cup to the front leading cup, and the flexible compression sleeve means includes a series of metallic disk elements stacked adjacent to each other, and at least a unitary resilient body interposed between two metallic disk elements.