FR2416337A1 - Sliding ram for positioning and recovering borehole equipment - has radially moving balls locking double spring-loaded hammer - Google Patents

Abstract

A sliding ram for use down boreholes comprises two organs acting as a hammer and an anvil, assembled telescopically, so that one can strike the other after relative movement longitudinally between them in one direction; a locking mechanism including balls which move laterally so as to engage with one of the organs, and can be displaced longitudinally relatively to the second organ; a ramming spring assembled between the locking mechanism and the second organ, which by resisting compression, obstructs the relative longitudinal displacement of the organs in the direction mentioned, when the locking mechanism is engaged with the first organ; a support surface on the second organ for keeping the locking mechanism engaged with the first organ; and first means of disengagement on the second organ which allow the balls of the locking mechanism to retract from the first organ, when the ramming spring reaches a predetermined compressive force. During the relative displacement of the organs in the direction, space is provided to allow the detenting of the ramming spring, and there are also second means on the second organ, which include a balancing spring, to bring about the re-engagement of the locking mechanism with the first organ, after a relative longitudinal displacement of the organs in the opposite direction. Provides a means by which tools, valves, etc. can be positioned down a borehole and recovered therefrom. In particular, the sliding ram, attached to a steel cable with weighting bars, etc. makes it possible to hammer an object wedged in the prod. pipe or held by shear pins, and release it. The sliding ram is of a much simpler design than existing tools for this purpose but functions reliably and efficiently.