Tube pulling device

Claim 1

A tube pulling device, comprising: a body having an operating chamber therein at the rearward end and having an open bucking sleeve connected thereto at the forward end for bucking engagement with a tube sheet or the like; an outer piston disposed in said operating chamber for sealing engagement with the wall thereof and for movements therein in response to fluid pressure acting on opposite sides thereof; a tubular assembly with said outer piston and extending forwardly therefrom in said bucking sleeve to form a forward piston surface; tube gripping means mounted at the forward end of said tubular assembly for longitudinal movement therewith and for gripping engagement with the inner wall of a tube; an inner piston slidably mounted in a rear-ward portion of said tubular assembly and forwardly of said outer piston for longitudinal movements relative to said outer piston and having a piston rod with a hollow bore forwardly thereof; expander means operably connected to saiD inner piston by said piston rod for expanding said tube gripping means into gripping engagement with a tube upon a rearward longitudinal movement of said inner piston relative to said outer piston, and said expander means and gripping means having co-acting surfaces for preventing further rearward longitudinal movement of said inner piston relative to said outer piston after said gripping means is in gripping engagement with the tube: fluid passage means mounted with said body and including a fluid control tube mounted in said operating chamber and extending through said outer piston and said inner piston for directing fluid forwardly of said inner piston and said outer piston; said hollow bore of said piston rod receiving said tubular passage member and having an open port means establishing fluid communication with the forward side of said inner piston; said tubular assembly having an open port means forwardly of said inner piston and establishing communication between the area forwardly of said inner piston and the area in said chamber forwardly of said forward piston surface for constantly exposing said outer piston to the fluid force acting on said inner piston but substantially equalizing said fluid force acting on said outer piston until the rearward movement of said inner piston relative to said outer piston is stopped by the coaction between said expander means and said gripping means; and said outer piston having an inner piston surface with substantially the same area exposed to fluid pressure as the area of said inner piston for thereby cancelling the effectiveness of said fluid force acting on said inner piston surface and said inner piston when the rearward movement of the inner piston has stopped, whereby the fluid force then acts upon said outer piston surface to move said outer piston and said inner piston rearwardly together for pulling the tube from the tube sheet or the like.