Safety switching system for clamping devices for pipes

Abstract

The invention relates to a safety switching system for a clamping device, provided with clamping wedges and operable by a flowing medium for holding and/or lowering or raising a pipe string, with which a borehole is lined in order to support the rock and create a transport line, characterized in that there is attached to a clamping wedge holder of the clamping device a trip cam for a safety switching valve which is mounted at the basic body of the clamping device and is actively connected to the trip cam when the clamping wedges assume their prescribed clamping position on the pipe string. In another aspect, a safety switching system for use with a string of tubulars may include a clamping device having one or more movable wedges for clamping the tubular; a cam member attached to one of the one or more movable wedges, the cam member movable therewith and includes a switching surface and one or more ramp surfaces, and a safety switch disposed on an adjacent surface, the safety switch constructed and arranged to become actuated by the cam member when the string of tubulars is in a predetermined position within the clamping device.

Dependencies are inferred from the claim text.